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ArticleFebruary 9, 2022

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis
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Allegra Franchino
Allegra Franchino
Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
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Àlex Martí
Àlex Martí
Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
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Antonio M. Echavarren*
Antonio M. Echavarren
Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
*[email protected]
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https://orcid.org/0000-0001-6808-3007

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Journal of the American Chemical Society

Cite this: J. Am. Chem. Soc. 2022, 144, 8, 3497–3509

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https://doi.org/10.1021/jacs.1c11978

Published February 9, 2022

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Abstract

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A new strategy for enantioselective transition-metal catalysis is presented, wherein a H-bond donor placed on the ligand of a cationic complex allows precise positioning of the chiral counteranion responsible for asymmetric induction. The successful implementation of this paradigm is demonstrated in 5-exo-dig and 6-endo-dig cyclizations of 1,6-enynes, combining an achiral phosphinourea Au(I) chloride complex with a BINOL-derived phosphoramidate Ag(I) salt and thus allowing the first general use of chiral anions in Au(I)-catalyzed reactions of challenging alkyne substrates. Experiments with modified complexes and anions, ¹H NMR titrations, kinetic data, and studies of solvent and nonlinear effects substantiate the key H-bonding interaction at the heart of the catalytic system. This conceptually novel approach, which lies at the intersection of metal catalysis, H-bond organocatalysis, and asymmetric counterion-directed catalysis, provides a blueprint for the development of supramolecularly assembled chiral ligands for metal complexes.

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Note Added after ASAP Publication

This paper was published February 9, 2022. References 2a,b have been added and the paper was re-posted February 17, 2022.

Introduction

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Groundbreaking work by Toste and co-workers proved that it was possible to perform gold catalysis enantioselectively by using achiral ligands together with chiral anions, combining a dinuclear gold complex with a chiral silver phosphate to realize the asymmetric cyclization of allenes (Scheme 1A). (1) This contributed to the development of the field of “asymmetric-counteranion directed catalysis” (ACDC), (2) and chiral anions have since been employed as stereodirecting elements in other Au(I)-catalyzed transformations, in combination with both achiral (3) and chiral (4) gold complexes. However, nearly all examples of Au(I)-ACDC reported to date refer to reactions of prochiral allene substrates. (3,4) The only exceptions are the desymmetrization of diynes described by the group of Czekelius (Scheme 1B) (5) and cases of tandem Au/chiral acid catalysis wherein gold is generally not involved in the enantiodetermining Brønsted acid-catalyzed step. (6) To the best of our knowledge, all other attempts to leverage chiral counterions in more challenging asymmetric Au(I)-catalyzed reactions of alkynes, (7) which, unlike allenes, cannot be prochiral in themselves, were met with failure until now. In this regard, our group reported that mixing triphenylphosphinegold(I) chloride with BINOL-derived silver phosphates affords neutral gold complexes with an anionic phosphate ligand, which are not catalytically competent in enyne cycloisomerizations. (8) In fact, the counteranion has a profound impact on the reactivity and selectivity of all gold-catalyzed transformations, since properties such as its basicity, coordinating ability, and steric bulk influence the energy barriers for various elementary steps of the catalytic cycle. (9,10)

Scheme 1. Asymmetric Counterion-Directed Gold Catalysis

A further layer of complexity is added when the anion is chiral, as its position with respect to the reaction center, key for a successful ACDC, depends on difficult-to-predict electrostatic interactions with the cationic complex/intermediate or on the presence of a protic group on the substrate. Therefore, in the vast majority of cases, the noncovalent interactions required for enantioinduction (11) are not built into the catalytic system a priori but rather selected during optimization by a lengthy trial-and-error approach and rationalized only aposteriori. (12) Alternatively, the chiral anion can be precisely positioned by a rigid covalent linkage to the ligand, as in the “tethered counterion-directed catalysis” strategy recently disclosed by Marinetti, Guinchard, and co-workers for the enantioselective Au(I)-catalyzed tandem cycloisomerization–nucleophile addition to 2-alkynyl enones. (13) However, despite its elegance, this latter approach becomes akin to using a chiral ligand, so it is devoid of the flexibility and combinatorial potential offered by the original two-component ACDC.

Herein we detail a conceptually novel “H-bonded counterion-directed catalysis” strategy that enables the first general use of chiral anions in gold(I)-catalyzed reactions of alkyne substrates, as opposed to well-established allenes (Scheme 1c). Various bi- and tricyclic structures were accessed in good to excellent yield and enantioselectivity from 1,6-enynes, via 5-exo-dig and 6-endo-dig cyclizations with or without external nucleophiles. (14) To overcome the reactivity (8) and enantiocontrol (15) challenges described above, we envisioned to prepare gold(I) complexes with bifunctional phosphine ligands (16) incorporating dual H-bond donor groups (17) such as (thio)ureas (18) and combine them with BINOL-derived chiral anions (19) (Scheme 2). The pendant H-bond donor would serve two purposes: (1) remove the chiral anionic ligand from the Au(I) coordination sphere, thus enabling substrate coordination and subsequent catalysis at the metal center; (2) place the chiral anion close to the substrate, ensuring good transmission of the stereochemical information.

Scheme 2. Design for Asymmetric H-Bonded Counterion-Directed Au(I) Catalysis

The feasibility of ligand abstraction via H-bonding interactions was supported by our previous studies on the self-activation of Au(I) chloride complexes featuring PPh₃-based phosphinosquaramides and phosphinoureas. (18b) Regarding stereochemical considerations, we chose Buchwald-type phosphines functionalized at the meta or para position of the distal aryl ring due to both their easy electronic tuning and attractive geometric features in the context of linear dicoordinated Au(I) complexes (Scheme 2). (16,20) In fact, the blocked rotation about the P–C_aryl bond, enforced by the interlocking of the ortho-proton H_o between the two bulky alkyl groups, causes the P–Au–Cl and biphenyl axes to be parallel. This in turn projects the urea “anchor” for the chiral anion close to the substrate coordination site. This H-bonded ACDC approach features a modular and easy synthesis for both pieces of the catalytic system, which would click together based on predictable, well-precedented H-bond interactions between (thio)ureas and phosphate anions. (21) This strategy can thus benefit from all the typical advantages offered by supramolecularly assembled ligands for enantioselective metal catalysis, (22) most notably (i) simple preparation and tuning of the two components, which avoids long syntheses of new chiral ligands from scratch, and (ii) generation of a large library of catalysts through combinatorial and potentially automated methods, with the aim to speed up screening and optimization.

Results and Discussion

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Synthesis of the Components of the Catalytic System

The bifunctional phosphino(thio)urea Au(I) chloride complexes were prepared with a high-yielding and modular three-step sequence from bromoanilines A1–3, in turn accessible in one or two steps from commercial building blocks (Scheme 3, see Supporting Information for details). A well-scalable Pd-catalyzed P–C coupling (23) allowed the introduction of different phosphine substituents on the biphenyl scaffold without the need to protect the free amine group. In this sense, the use of potassium phosphate in place of stronger bases such as sodium tert-butoxide was instrumental in suppressing undesired Buchwald–Hartwig coupling between the aryl bromide and the NH₂ group. Phosphinoanilines B1–5 were then reacted with the iso(thio)cyanate of choice for the late-stage introduction of the key H-bond donor on ligands L1–13. Finally, ligand exchange with [(Me₂S)AuCl] afforded Au(I) chloride complexes Au1–13. Thus, all complexes were prepared in four to five total steps and 42–60% overall yields except for Au12 featuring an N-aryl-N′-alkylurea, obtained in 31% overall yield. Previously described complexes Au14–16 with a triarylphosphine backbone were included for comparison. (18b)

Scheme 3. Synthesis of Phosphino(thio)urea Au(I) Chloride Complexes **Au1**–13^a

Representative complexes were characterized also by single crystal X-ray diffraction (see Supporting Information for a complete overview). In the solid state, all novel phosphinourea Au(I) complexes display an intact Au–Cl bond with the P–Au–Cl axis nearly parallel to the biphenyl axis, as expected. The urea moiety generally adopts an anti,anti-conformation (Au1, Au6, Au10, and Au13) but displays the much rarer anti,syn one (24) in Au4 and Au8 and shows various degrees of out-of-plane twisting of the aryl substituents (compare Au1 and Au10 in Scheme 3). In the solid state, the urea group establishes H-bonds either with chloride ligands or with other urea units, depending on the ligand scaffold. As for phosphinothiourea Au(I) complexes, Au7 possessing a para-substituted ligand shows a classical [LAuCl] structure with intramolecular NH···Cl contacts. In the crystal structure of Au9, on the contrary, the S atom of the meta thiourea coordinates to gold with an almost linear P–Au–S axis, while the displaced chloride ion is stabilized by two H-bonds with the NH groups.

Regarding the other component of the catalytic system, we planned to introduce the chiral anion as a metal salt in order to simultaneously scavenge the chloride ligand from the Au(I) center. To this end, eight chiral salts (Ag1–6, Na6, and Cu6) were synthesized in 2–3 steps and 30–77% overall yield from commercially available (R)-configured binaphthols C1–4 (Scheme 4). After treatment of the latter with phosphoryl chloride, the desired sulfonamide was added to the reaction mixture affording phosphoramidates (25)D1–6. Deprotonation of these Brønsted acids with silver carbonate delivered chiral silver salts Ag1–6. Crystals of Ag6 grown in toluene/pentane reveal a dimeric structure where the anion behaves as a bidentate O,O-ligand through the phosphoryl and sulfonyl O atoms (Scheme 4). The Ag(I) centers are further stabilized by η²-interactions with the anthracenyl substituents, and one of them is also bound in a η¹/η² fashion to a molecule of toluene.

Scheme 4. Synthesis of Ag(I), Na(I), and Cu(II) Chiral Salts^a

Optimization

Having built the library of [LAuCl] complexes and chiral anions, to validate our H-bonded ACDC design, we investigated the cycloisomerization of 1,6-enynes of type 1 (Table 1), (26,27) a reaction that did not proceed at all employing [(Ph₃P)Au(TRIP)]. (8) We commenced by screening different silver salts in combination with phosphinourea gold(I) chloride Au1 at room temperature. This complex combined with AgTRIP was catalytically inactive, whereas together with less basic N-triflyl phosphoramidate (25) salt Ag1 afforded the desired product 2a in good yield and encouraging 79:21 er (Table 1, entries 1 and 2). The more basic N-mesyl and N-phenylsulfonyl analogues Ag2 and Ag3 induced comparable enantioselectivity but much lower reactivity (Table 1, entries 3 and 4). A clear trend between reactivity and basicity emerged: less basic counterions from stronger parent Brønsted acids (19,28) are essential for reactivity presumably because they coordinate less strongly to the cationic Au(I) center (which is isolobal to a proton) (29) and therefore can be abstracted more easily via H-bonds. Among N-triflyl phosphoramidate salts, Ag1 provided better enantiocontrol than Ag4 and Ag5 (Table 1, entries 5 and 6), which bear different groups at the 3,3′-positions of the binaphthol backbone. Overall, the results summarized in Table 1 indicate that for a given anion, substitution at phosphorus influences basicity and coordinating ability, hence reactivity, while 3,3′ residues are responsible for enantioselectivity, as expected. (30)

Table 1. Screening of Silver Salts with Au1

entry	(R)-AgX	time (h)	yield (%)^a	er^b
1	AgTRIP	96	<5
2	Ag1	4.5	70	79:21
3	Ag2	4.5	7	81.5:18.5
4	Ag3	4.5	9	83.5:16.5
5	Ag4	4.5	42	57:43
6	Ag5	4.5	22	51:49

^{^a}

Determined by ¹H NMR against internal standard.

^{^b}

Determined by HPLC on chiral stationary phase.

Next, the library of gold complexes was evaluated with the optimal silver salt (R)-Ag1. Only key data providing insight into the working mode of the catalytic system are shown in Table 2 (see Supporting Information for comprehensive optimization studies). The presence of the urea group on the ligand is important for reactivity and essential for enantioselectivity, as [(JohnPhos)AuCl] with Ag1 delivered product 2a in lower yield and racemic form (Table 2, entries 1 and 2). Complex Au5, the thiourea analogue of Au1, was completely inactive, most likely because the S atom of the thiourea coordinates too strongly to the metal center, preventing substrate activation. This is consistent with the known thiophilicity of gold, (31) the Au–S bond observed in the crystal structure of related Au9, and previous studies on PPh₃-based phosphinothourea Au(I) complexes. (18b) Moving the urea group from the para to the meta position of the biphenyl scaffold reversed the sense of enantioinduction (Table 2, entry 4 vs 1). Remarkably, either enantiomer of the product can thus be obtained preferentially using the same enantiomer of the chiral anion, in combination with a different achiral cocatalyst. Complexes Au14–16, equipped with urea or squaramide groups on triarylphosphine scaffolds, (18b) were poorly active and afforded (almost) racemic product (Table 2, entries 5–7).

Table 2. Screening of Selected Au(I) Complexes with Ag1

entry	LAuCl	time (h)	yield (%)^a	er^b
1	Au1	4.5	70	79:21
2	[(JohnPhos)AuCl]	6	40	50:50
3	Au5	44	0
4	Au8	4.5	70	27.5:72.5
5	Au14	44	32	50:50
6	Au15	44	10	45:55
7	Au16	24	46	56:44
8^c	Au1	0.7	90	87:13

^{^a}

Determined by ¹H NMR against internal standard.

^{^b}

Determined by HPLC on chiral stationary phase.

^{^c}

In benzene.

This data set highlights that a H-bond donor on the ligand is crucial for both reactivity and enantiocontrol. The mere presence of a chiral anion in the reaction mixture is not sufficient to transfer effectively the stereochemical information, as its proximity to the reaction center cannot be guaranteed in the absence of a suitably placed H-bond donor. These observations lend credibility to the original design, wherein the pendant urea was envisioned to enable both anion abstraction and precise positioning of the source of chirality (Scheme 2). The presence of H-bonding at the heart of the catalytic system can be inferred also from solvent effects. For instance, the performance of the optimal Au1/Ag1 combination improved by replacing dichloromethane with benzene (Table 2, entry 1 vs 8, 79:21 vs 87:13 er). The enantiocontrol generally increased at −20 °C (Table 3). A qualitative correlation between solvent polarity (defined by E^N_T values) (32) and enantioselectivity levels was observed, in agreement with H-bonding interactions between the urea and the anion being favored in apolar solvents. The least polar solvent for either the chlorinated or aromatic series (chloroform for entries 1–3 and toluene for entries 4–8 in Table 3) delivered the product with the highest enantiomeric ratio, up to 94.5:5.5 er.

Table 3. Solvent Effect with Au1/Ag1 Catalytic System^a

entry	solvent	E^N_T (ref (32))	yield (%)^a	er^b
1	CHCl₃	0.259	39	93:7
2	CH₂Cl₂	0.309	85	92:8
3	ClCH₂CH₂Cl	0.327	60	88:12
4	C₆H₅CH₃	0.099	>95	94.5:5.5
5	1,2-(CH₃)₂C₆H₄	na	86	93:7
6	C₆H₅Cl	0.188	>95	91:9
7	C₆H₅F	0.194	75	90:10
8	C₆H₅CF₃	na	89	90.5:9.5

^{^a}

Determined by ¹H NMR against internal standard.

^{^b}

Determined by HPLC on chiral stationary phase.

Once identified toluene as the best solvent, a final fine-tuning of the catalytic system was performed (Table 4). Replacing Ag1 with Ag6, i.e., swapping the triisopropylphenyl groups for 9-anthracenyl substituents at the 3,3′-binaphthol positions, led to a considerable improvement in enantioselectivity, although at the expense of conversion (Table 4, entries 1 and 2). In order to increase reactivity, more electrophilic Au(I) complex Au10 with a trifluoromethyl group meta to the phosphine was employed, and an excellent yield of 2a could be obtained at −10 °C while maintaining the high enantioselectivity (Table 4, entries 3 and 4). Complexes Au2–4, Au11, and Au12 with different substituents on the urea were also evaluated, since electronic properties influence H-bonding ability. (17,21) However, none of them surpassed the performance of complex Au10 possessing a simple phenyl urea, which offered the right balance between electronic activation and steric hindrance (see Supporting Information for details).

Table 4. Fine Tuning of the Catalytic System^a

entry	LAuCl	(R)-AgX	T (°C)	yield (%)^a	er^b
1	Au1	Ag1	–20	>95	94.5:5.5
2	Au1	Ag6	–20	50	98:2
3	Au10	Ag6	–20	78	98:2
4	Au10	Ag6	–10	>95	98:2

^{^a}

Determined by ¹H NMR against internal standard.

^{^b}

Determined by HPLC on chiral stationary phase.

Generality of the Enantioselective 5-exo-dig and 6-exo-dig Cyclizations

The substrate scope of the formal [4 + 2] cycloaddition of enynes 1 catalyzed by the Au10/Ag6 system was then assessed (Scheme 5). Enynes 1a–h bearing various linkers underwent cyclization to deliver the corresponding products 2a–h in high yield (84–95%) and with excellent enantioselectivity (96:4 to 98:2 er). The standard reaction to 2a could be performed on 2-mmol scale in 24 h under air and in technical-grade toluene, with Au(I) and Ag(I) loading reduced to 1 mol %, with a 99% yield and 98:2 er for the product. This catalyst loading is the lowest reported so far in asymmetric cycloisomerizations of enynes 1, which is remarkable considering that all previous methods relied on stereochemical information covalently embedded in a chiral ligand. (27) Apart from ethers (2a, 2b), also allyl (2c), ester (2d, 2h), carbamate (2e), tosylate (2f), and acetal groups (2g) were tolerated. As for variations on the alkyne moiety, products with electron-poor as well as electron-rich groups at the para (2i–l), ortho (2m,n), and meta position (2o,p) of the aromatic ring were obtained with good to excellent yield and enantiocontrol (85–98%, 89.5:10.5 to 98.5:1.5 er). Also substrates 1q and 1r, possessing respectively 1-naphthyl and benzothiophenyl substituents at the alkyne terminus, underwent reaction smoothly and enantioselectively. The attainment of such high levels of enantiocontrol across a broad scope is unprecedented in this transformation. (27)

Scheme 5. Enantioselective Formal [4 + 2] Cycloadditions of 1,6-Enynes Based on 5-*exo*-dig Cyclizations^a

Compared to linker and alkyne variations, the catalytic system showed higher sensitivity to changes to the alkene part (compare 2a with 2s–w in Scheme 5), in line with the fact that the chiral catalytic ensemble needs to discriminate the two enantiotopic faces of the double bond. Thus, enynes 1s and 1t possessing geranyl or trans-cinnamyl groups cyclized to products 2s and 2t in less than 48 h (90–99% yield, 89:11 to 95.5:4.5 er), even though higher temperatures and/or catalyst loadings were required. Nevertheless, this marks a significant improvement with respect to previous chiral gold catalysts, which required 7–14 days at room temperature. (27e) Enyne 1u possessing a cis-cinnamyl substituent afforded product 2u in lower yield (48%, due to a competing cycloisomerization to an achiral diene product) and enantioselectivity (82:18 er). Formation of epimeric products 2t and 2u highlights the stereospecificity of the reaction with respect to the alkene configuration. More hindered substrates such as 1v and 1w, bearing respectively a cyclohexene or a tetrasubstituted alkene, delivered products 2v and 2w in good yield (61–95%) and moderate but encouraging enantioselectivity (80:20 to 85:15 er), considering that such bulky enynes were never engaged in this cycloisomerization, let alone asymmetrically.

Judging by the enantioselectivity of the 5-exo-dig cyclizations presented in Scheme 5, the key interaction between the urea and the anion is not disrupted by H-bond acceptors on the substrates (such as ester, carbamate, tosylate, and nitro groups in 1d–f, 1h, 1l), even though they are present in up to 40-fold excess with respect to the chiral anion. Protic additives with H-bond donor ability were also tolerated, as spiking the reaction of model enyne 1a with 5 equiv of methanol still delivered product 2a in 80% NMR yield and 97:3 er. These observations suggest that H-bonding between the urea and the anion is strong enough to make for an effective and robust catalytic system, even if based on noncovalent interactions. To further prove this point, the Au10/Ag6 catalytic system was applied also to the 6-endo-dig cyclization of enynes, with and without the addition of protic exogenous nucleophiles (Scheme 6).

Scheme 6. Enantioselective 6-*endo*-dig Cyclizations of 1,6-Enynes without (A) or with (B) Nucleophile Addition^a

Thus, O-tethered enyne 3 was converted to oxabicyclo[4.1.0]hept-4-ene 4 in 70% yield and 92.5:7.5 er. (33) Cyclization of benzene-tethered enyne 5 followed by the addition of O-based nucleophiles (27e,34) delivered compounds 6a–e in moderate to good yield and er (55–77%, 88.5:11.5 to 92.5:7.5 er). (35) The addition of a N-centered nucleophile to enynes of type 5 was demonstrated for the first time, obtaining azide 6f in 62% yield and 90:10 er. Instead, fluoride addition afforded product 6g in 69% yield and only 61:39 er. The low enantiocontrol in the formation of 6g can be explained by the strong tendency of the fluoride ion to H-bond with the urea, (36) thus preventing the key interaction that keeps the chiral anion in place.

Importantly, derivatization of the water- and azide-addition products gave access to O- and N-derivatives equivalent to the formal addition of noncompetent nucleophiles, thus expanding the scope and underlying the usefulness of this enantioselective protocol. For example, alcohol 6a was transformed into benzoate 6h, as well as into diene 7, which displays the core of the carexane natural products (Scheme 7A). (27e,37) Triazole 6i, primary amine 6j, and amide 6k were easily obtained from azide 6f without erosion of the enantiopurity (Scheme 7B). Cyclizations of 1,6-enynes bearing a terminal alkyne generally proceeded with lower enantioselectivity than those of internal aryl alkyne substrates (Scheme 7C). The methoxycyclization of benzene-tethered enyne 8 delivered product 9 in 94% yield and 78.5:21.5 er, which could be increased to 87:13 er at the expense of yield (see Supporting Information for details). (38) In order to preserve the stereocenter, the cyclopropyl gold carbene generated upon 5-exo-dig cycloisomerization of O-tethered enyne 10 was trapped in situ with diphenyl sulfoxide. (39) Under unoptimized conditions, cyclopropyl aldehyde 11 was obtained in 42% yield and 83:17 er, which compares favorably with the only other enantioselective preparation reported so far (3% ee). (40)

Scheme 7. Derivatization and Scope Extension

Finally, we sought to extend this H-bonded counterion-directed catalysis strategy to other types of reactions. At 1 mol % loading, phosphinosquaramide complex Au16 in combination with (R)-Ag6 catalyzes the tandem cyclization–indole addition to 2-alkynyl enones 12, affording furans 14a–d in good yield and enantioselectivity (Scheme 8). (41,13) In this case, the stereocenter is not created during the cycloisomerization but forms in the subsequent intermolecular nucleophilic attack to a carbocation intermediate. Chiral salt (R)-Ag6 alone affords predominantly the opposite enantiomer of product 14a, and the Au10/(R)-Ag6 combination employed for 1,6-enynes gives slightly lower enantioselectivity. These results indicate that tuning of the achiral catalytic component to get high enantioselectivity is required for each reaction class (see Supporting Information for more examples, including an allenol (1) cyclization).

Scheme 8. Enantioselective Cycloisomerization–Indole Addition to 2-Alkynyl Enones^a

Mechanistic Studies

Additional control experiments were conducted to shed light on the working mode of the final, optimized Au10/Ag6 catalytic system (Scheme 9 and Table 5, see Supporting Information for further tests). To this end, cationic complex Au17 was prepared by treatment of Au10 with equimolar AgSbF₆ in the presence of acetonitrile. Its structure was confirmed by X-ray diffraction, showing that in the solid state the urea H-bonds to the fluoride of the counteranion. When AgSbF₆ was replaced by (R)-Ag6, neutral complex Au18 was isolated instead, with no incorporation of acetonitrile as indicated by NMR.

Scheme 9. Synthesis of Complexes with Ureaphosphine **L10**

Table 5. Control Experiments

entry	[Au]	[Na or Ag]	yield (%)^a	er^b
1	Au10	(R)-Ag6	>95	98:2
2	Au18		>95	93:7
3	[(JohnPhos)AuCl]	(R)-Ag6	0
4	Au10	(R)-Na6	0
5	[(JohnPhos)Au(NCMe)]SbF₆	(R)-Ag6	24	50:50
6	[(JohnPhos)Au(NCMe)]SbF₆	(R)-Na6	3	50:50
7	Au17	(R)-Ag6	>95	50:50
8	Au17	(R)-Na6	>95	79:21
9^c	Au17	(R)-Na6	>95	90:10

^{^a}

Determined by ¹H NMR against internal standard.

^{^b}

Determined by HPLC on chiral stationary phase.

^{^c}

With 15-crown-5 (100 mol %).

These complexes were then used in a series of informative control experiments, which highlighted how the chloride ligand and the countercation of the chiral salt play a role too (Table 5). Preformed complex Au18 delivered product 2a with yield and enantioselectivity comparable to the in situ combination of Au10 and (R)-Ag6 (93:7 er vs 98:2 er, Table 5, entries 1 and 2). No reactivity was detected employing either [(JohnPhos)AuCl] with (R)-Ag6 or Au10 with (R)-Na6 (Table 5, entries 3 and 4), indicating respectively that the urea is required to remove the chiral anion from Au and that sodium, unlike silver, is not able to scavenge the chloride ligand. Experiments with cationic complexes Au17 and its urea-free counterpart [(JohnPhos)Au(NCMe)]SbF₆ were then performed. Combining [(JohnPhos)Au(NCMe)]SbF₆ with (R)-Ag6 and (R)-Na6 delivered racemic material in low yield (Table 5, entries 5 and 6), thus emphasizing the importance of the tethered urea not only for reactivity but also for enantioselectivity, achieved through precise positioning of the chiral anion via H-bonding. In an apparently surprising outcome, also cationic complex Au17 combined with (R)-Ag6 yielded racemic product (Table 5, entry 7). This can actually be explained by catalysis carried out by achiral cationic species Au17 on its own, because the chiral anion associates preferentially to Ag⁺ over Au⁺ (or the urea). In agreement with this picture, product 2a was obtained with 79:21 er when (R)-Na6 was used (Table 5, entry 8). Moreover, when 1 equiv of 15-crown-5 ether was added in order to chelate Na⁺ and thus direct the anion to Au⁺, the enantiomeric ratio of the product further improved to 90:10 (Table 5, entry 9). Therefore, in order to attain high enantioselectivity using this H-bonded system, it is crucial to tie the generation of the catalytically competent cationic Au(I) center to the removal of other cations (Ag⁺ and to a lesser extent Na⁺), which would otherwise “sequester” the chiral anion, leading to racemic background reactivity. In this sense, when combining Au10 and (R)-Ag6in situ, precipitation of AgCl not only frees up a coordination site on gold but also ensures that Ag⁺ is removed from deleterious solution equilibria with the anion.

Further insights into the catalytic system are presented in Scheme 10. First of all, single-crystal X-ray diffraction of products 2h and 6a and comparison of optical rotations with available literature values indicate that the newly created stereocenter is (R)-configured in both 5-exo-dig and 6-endo-dig reactions. This implies that in the enantiodetermining step of both cyclization modes, the Si face of the alkene attacks the Au(I)-activated alkyne, delivering the corresponding cyclopropyl Au(I) carbene intermediates (Scheme 10A). The absence of nonlinear effects (Scheme 10B) suggests that only one chiral anion is involved in the enantiodetermining step, in line with formation of the expected 1:1 urea:anion complex. (21b,c)

Scheme 10. Mechanistic Investigations: (A) Enantiofacial Selectivity, (B) Study of Nonlinear Effects, (C) Use of Complex **Au4** as **Au10** Surrogate, (D) ¹H NMR Titration of **Au4** with (R)-Na6 (298 K, CD₂Cl₂), (E–J) Kinetic Studies

Spectroscopic observation of the H-bonding interaction between the urea of complex Au10 and the chiral anion proved to be nontrivial. Mixing of Au10 and (R)-Ag6, in various ratios and in the absence of substrate, invariably resulted in at least partial chloride abstraction. In turn this led to poorly resolved NMR spectra, where species tentatively identified as chiral [LAuX] Au18 with the anion behaving as anionic ligand, and achiral chloride-bridged dinuclear complexes predominated. On the other hand, when Na6 was used instead of Ag6 to circumvent chloride scavenging, no changes were detected by NMR. In this last case, the chiral anion presumably remained associated with Na⁺ without interacting at all with the neutral urea. We resorted to study the combination of (R)-Na6 and complex Au4 in the presence of a constant excess of 15-crown-5, to force dissociation of the sodium cation, while at the same time avoiding undesired chloride scavenging. Au(I) chloride complex Au4 was chosen as a convenient surrogate for Au10, since the NH signals of its bis(trifluoromethyl)phenylurea resonate in a free region of the ¹H NMR spectrum. The performance of Au4 in the standard asymmetric reaction is comparable to that of Au10, even if with marginally lower reactivity (consistent with the absence of the meta CF₃ group) and enantioselectivity (Scheme 10C). Gratifyingly, ¹H NMR titration of complex Au4 (10 mM in CD₂Cl₂ at 25 °C) with increasing amounts of (R)-Na6 in the presence of 20 equiv of 15-crown-5 resulted in clear deshielding of both NH signals of the urea, indicating their engagement in H-bonds with the anion (Scheme 10D). (42) The titration was recorded at the same catalyst concentration present in the reaction mixtures (5–10 mM), and the establishment of such H-bonds during the reaction is expected to be entropically even more facile because after AgCl precipitation the Au(I)-bound chiral anion should already be in close proximity to the H-bond donor.

Finally, kinetic studies on the cycloisomerization of 1a to 2a catalyzed by the Au10/(R)-Ag6 system in toluene-d₈ at −10 °C were undertaken. By use of the variable time normalization analysis (VTNA) introduced by Burés, (43) the reaction was found to be approximately first order in catalyst (0.9) and 0.5 order in substrate (Scheme 10E,F). A first order in catalyst is common to most catalyzed transformations, provided that the catalyst does not decompose or aggregate into off-cycle species. A partial, noninteger order in substrate is expected for unimolecular catalyzed reactions that follow Briggs–Haldane kinetics (44) and possess a Michaelis–Menten constant (45) (K_M) similar to substrate concentration. (18b) To verify that this was indeed the case for the cycloisomerization under study, the reaction progress kinetic analysis (RPKA) popularized by Blackmond (46) was carried out. ¹H NMR monitoring of the reaction indicated clean conversion of enyne 1a to product 2a (Scheme 10G), but rate analysis revealed an initial induction period (Scheme 10H), most likely related to a noninstantaneous chloride abstraction. (47) The double reciprocal Lineweaver–Burk plot was thus constructed using data in the 1.5–10 h time range (Scheme 10I), (48) obtaining a Michaelis–Menten constant (K_M) of 74 ± 4 mM. (49) Given the 0–100 mM substrate concentration present during the reaction, this intermediate K_M value justifies the partial order in substrate determined by VTNA. The experimental 0.5 order found for the entire reaction course falls within the range of the calculated elasticity coefficient ε, (50) which predicts the changing order in substrate for Briggs–Haldane kinetic regimes from K_M and substrate concentration (Scheme 10J).

Scheme 11 presents a tentative mechanism for the enantioselective formal [4 + 2] cycloaddition of enyne 1a catalyzed by Au10/(R)-Ag6, which takes into account all the experimental, spectroscopic, and kinetic evidence discussed above, as well as previous studies on this cycloisomerization. (26b,27e) Upon mixing Au(I) chloride complex Au10 with (R)-Ag6, neutral complex I possessing a phosphoramidate anionic ligand forms. The expected chloride scavenging accompanied by precipitation of AgCl matches the observed formation of a solution (with very few solid grains) upon addition of a solution of (R)-Ag6 to a thick whitish suspension of Au10 and enyne in toluene. Species I represents the entry to the catalytic cycle and coincides with Au18, prepared ex situ (see Scheme 9) and catalytically competent (see Table 5). In the presence of enyne 1, neutral complex I is proposed to be in equilibrium with cationic complex II, wherein the anion is H-bonded to the pendant urea and the alkyne coordinates to Au. The presence of this equilibrium is consistent with the partial order in substrate observed in the Briggs–Haldane kinetics. Additionally, H-bonding interactions between the anion and both NH groups of the urea were observed spectroscopically in a model system (see Scheme 10D). Regarding their precise geometrical arrangement, we propose that the NH residues establish two H-bonds with the phosphoryl O atom. This speculation is based on solid state considerations and DFT calculations with implicit solvent models. (51) In the crystal structures of (R)-Ag6 and related triethylammonium salt (R)-Et₃NH6, the P–O and S–O bonds are almost parallel with the two O atoms forming a ∼3 Å wide “pincer” (see inset in Scheme 11), while Au10 has a 2.0 Å H–H distance between the urea NH groups. The most stable conformer computed by DFT for the model diphenylurea–chiral phosphoramidate couple shows two H-bonds to the phosphoryl O atom; however, a conformer where the NH groups H-bond to both the phosphoryl and sulfonyl O atoms is only 0.8 kcal/mol higher in energy. (51)

Scheme 11. Proposed Mechanism for the Cyclization of Enyne 1 under H-Bonded Counterion-Directed Au(I) Catalysis

The enyne is expected to be oriented as depicted for complex II (Scheme 11), with the arene pointing toward the more crowded BINOL region and the linker in an unencumbered zone. This would be consistent with the lower er (92.5:7.5 to 95:5) observed in the cyclization of ortho-substituted substrates 1m, 1n, and 1q, which are not so well accommodated, and with the catalyst ability to tolerate instead even very bulky linkers on substrates 1a–g. At this point, the enantiodetermining C–C bond formation takes place, i.e., the attack of the Si face of the alkene to the activated alkyne, leading to cyclopropyl Au(I) carbene III. (52) Friedel–Crafts-type ring expansion, deprotonation of the Wheland intermediate, and protodeauration then afford species IV. Product/substrate ligand exchange is likely mediated by the anion (18b) via the intermediacy of species I, thus closing the cycle and releasing product 2.

Conclusions

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We describe the concept of asymmetric H-bonded counterion-directed catalysis, based on H-bonding interactions between a chiral anion and a suitably positioned H-bond donor group on JohnPhos-type ligands for Au(I). The presence of such interactions was substantiated by ¹H NMR titrations and structure–activity studies with modified ligands and chiral salts, as well as by the observed solvent and fluoride effects. For the first time, a broad range of alkyne substrates was engaged in challenging enantioselective gold-catalyzed reactions using chiral anions as the source of the stereochemical information, at catalyst loading down to 1 mol % and with excellent functional group tolerance.

This new paradigm, with a modular, short, and tunable synthesis of the two catalytic components, has the potential to speed up the development of enantioselective versions of various transition-metal catalyzed reactions, provided that the ligand for the metal of choice is equipped with a suitably placed H-bond donor group for a chiral anion.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.1c11978.

Optimization tables, procedures, characterization, kinetic data, NMR spectra, SFC and HPLC traces, DFT computations, crystallographic data (PDF)

ja1c11978_si_001.pdf (25.01 MB)

Accession Codes

CCDC 2107746–2107758 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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Author Information

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Corresponding Author
- Antonio M. Echavarren - Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain; Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain; https://orcid.org/0000-0001-6808-3007; Email: [email protected]
Authors
- Allegra Franchino - Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
- Àlex Martí - Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain; Departament de Química Orgànica i Analítica, Universitat Rovira i Virgili, C/Marcel·lí Domingo s/n, 43007 Tarragona, Spain
Notes
The authors declare no competing financial interest.

Acknowledgments

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We thank the MCIN/AEI/10.13039/501100011033 (Grants PID2019-104815GB-I00 and CEX2019-000925-S), the European Union (Horizon 2020 Marie Skłodowska-Curie COFUND Postdoctoral Fellowship 754510 to A.F.), the European Research Council (Advanced Grant 835080), the AGAUR (Grant 2017 SGR 1257 and FI Fellowship to À.M.), and CERCA Program/Generalitat de Catalunya for financial support. We also sincerely thank the ICIQ X-ray diffraction (especially Dr. Eduardo Escudero), NMR, chromatography, and mass spectrometry units.

References

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This article references 52 other publications.

1
Hamilton, G. L.; Kang, E. J.; Mba, M.; Toste, F. D. A Powerful Chiral Counterion Strategy for Asymmetric Transition Metal Catalysis. Science 2007, 317, 496– 499, DOI: 10.1126/science.1145229
Google Scholar
1
A powerful chiral counterion strategy for asymmetric transition metal catalysis
Hamilton, Gregory L.; Kang, Eun Joo; Mba, Miriam; Toste, F. Dean
Science (Washington, DC, United States) (2007), 317 (5837), 496-499CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
Traditionally, transition metal-catalyzed enantioselective transformations rely on chiral ligands tightly bound to the metal to induce asym. product distributions. High enantioselectivities conferred by a chiral counterion in a metal-catalyzed reaction are reported. Two different transformations catalyzed by cationic gold(I) complexes generated products in 90 to 99% enantiomeric excess with the use of chiral binaphthol-derived phosphate anions. Furthermore, the chiral counterion can be combined additively with chiral ligands to enable an asym. transformation that cannot be achieved by either method alone. This concept of relaying chiral information via an ion pair should be applicable to a vast no. of metal-mediated processes.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXotFyltbw%253D&md5=cf133b6947d52ee483d9be3ded331feb
2
(a) Mayer, S.; List, B. Asymmetric Counteranion-Directed Catalysis. Angew. Chem. Int. Ed. 2006, 45, 4193– 4195, DOI: 10.1002/anie.200600512
Google Scholar
2a
Asymmetric counteranion-directed catalysis
Mayer, Sonja; List, Benjamin
Angewandte Chemie, International Edition (2006), 45 (25), 4193-4195CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
Exceedingly high enantioselectivity in a catalytic reaction can be realized even when the chirality resides only in the counteranion of the catalyst. A salt composed of an achiral ammonium cation and a chiral binaphthalenediyl phosphate counteranion catalyzes asym. transfer hydrogenations of arom. and aliph. α,β-unsatd. aldehydes with a Hantzsch ester in excellent enantioselectivities.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XmsFyntrY%253D&md5=b5688d6aa76f6b9dc94b0ec710954166
(b) Mukherjee, S.; List, B. Chiral Counteranions in Asymmetric Transition-Metal Catalysis: Highly Enantioselective Pd/Brønsted Acid-Catalyzed Direct α-Allylation of Aldehydes. J. Am. Chem. Soc. 2007, 129, 11336– 11337, DOI: 10.1021/ja074678r
Google Scholar
2b
Chiral Counteranions in Asymmetric Transition-Metal Catalysis: Highly Enantioselective Pd/Bronsted Acid-Catalyzed Direct α-Allylation of Aldehydes
Mukherjee, Santanu; List, Benjamin
Journal of the American Chemical Society (2007), 129 (37), 11336-11337CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
A highly enantioselective Pd/chiral phosphoric acid-catalyzed α-allylation of α-branched aldehydes R1R2CHCHO (R1 = Me, R2 = Ph, 4-MeC6H4, 3-FC6H4, 2-naphthyl, cyclohexyl, 2-thienyl; R2R2 = 2-C6H4CH2CH2) with allylic amines R3CH:CHCH2NHR4 (R3 = H, Me, Ph, R4 = Ph2CH; R3 = H, R4 = PhCH2, 3,5-Me2C6H3CH2, etc.) as the allylating species that creates all-carbon quaternary stereogenic centers in high yields and enantioselectivities has been developed. To our knowledge, this is the first time that a chiral anionic ligand is applied for achieving asym. induction in a palladium-catalyzed allylic alkylation reaction.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsVeltL0%253D&md5=ab3844e9ac4b8206ede7bbe3f70a020d
(c) Phipps, R. J.; Hamilton, G. L.; Toste, F. D. The Progression of Chiral Anions from Concepts to Applications in Asymmetric Catalysis. Nat. Chem. 2012, 4, 603– 614, DOI: 10.1038/nchem.1405
Google Scholar
2c
The progression of chiral anions from concepts to applications in asymmetric catalysis
Phipps, Robert J.; Hamilton, Gregory L.; Toste, F. Dean
Nature Chemistry (2012), 4 (8), 603-614CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
A review. Despite the tremendous advances of the past four decades, chemists are far from being able to use chiral catalysts to control the stereoselectivity of any desired reaction. New concepts for the construction and mode of operation of chiral catalysts have the potential to open up previously inaccessible reaction space. The recognition and categorization of distinct approaches seems to play a role in triggering rapid exploration of new territory. This review both reflects on the origins as well as details a selection of the latest examples of an area that has advanced considerably within the past five years or so: the use of chiral anions in asym. catalysis. Defining reactions as involving chiral anions is a difficult task owing to uncertainties over the exact catalytic mechanisms. Nevertheless, the authors attempted to provide an overview of the breadth of reactions that could reasonably fall under this umbrella.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVOis7fL&md5=df30abefc42ad58cf9016f4cdb68f1ac
(d) Mahlau, M.; List, B. Asymmetric Counteranion-Directed Catalysis: Concept, Definition, and Applications. Angew. Chem., Int. Ed. 2013, 52, 518– 533, DOI: 10.1002/anie.201205343
Google Scholar
2d
Asymmetric Counteranion-Directed Catalysis: Concept, Definition, and Applications
Mahlau, Manuel; List, Benjamin
Angewandte Chemie, International Edition (2013), 52 (2), 518-533CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Recently, the use of enantiomerically pure counter anions for the induction of asymmetry in reactions proceeding through cationic intermediates has emerged as an exciting new concept, which has been termed asym. counteranion-directed catalysis (ACDC). Despite its success, the concept has not been fully defined and systematically discussed to date. This Review closes this gap by providing a clear definition of ACDC and by examg. both clear cases as well as more ambiguous examples to illustrate the differences and overlaps with other catalysis concepts.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslKmtr3L&md5=45faead19031c7cd7facbe5c8a2c0565
(e) Brak, K.; Jacobsen, E. N. Asymmetric Ion-Pairing Catalysis. Angew. Chem., Int. Ed. 2013, 52, 534– 561, DOI: 10.1002/anie.201205449
Google Scholar
2e
Asymmetric ion-pairing catalysis
Brak, Katrien; Jacobsen, Eric N.
Angewandte Chemie, International Edition (2013), 52 (2), 534-561CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Charged intermediates and reagents are ubiquitous in org. transformations. The interaction of these ionic species with chiral neutral, anionic, or cationic small mols. emerged as a powerful strategy for catalytic, enantioselective synthesis. This review described developments in the burgeoning field of asym. ion-pairing catalysis with an emphasis on the insights that were gleaned into the structural and mechanistic features that contribute to high asym. induction.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslKmtr3E&md5=0221ea269c66cfec291e427012d7fbfb
(f) Shirakawa, S.; Maruoka, K. Recent Developments in Asymmetric Phase-Transfer Reactions. Angew. Chem., Int. Ed. 2013, 52, 4312– 4348, DOI: 10.1002/anie.201206835
Google Scholar
2f
Recent Developments in Asymmetric Phase-Transfer Reactions
Shirakawa, Seiji; Maruoka, Keiji
Angewandte Chemie, International Edition (2013), 52 (16), 4312-4348CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Phase-transfer catalysis has been recognized as a powerful method for establishing practical protocols for org. synthesis, because it offers several advantages, such as operational simplicity, mild reaction conditions, suitability for large-scale synthesis, and the environmentally benign nature of the reaction system. A wide variety of asym. transformations catalyzed by chiral onium salts and crown ethers have been developed for the synthesis of valuable org. compds. in the past several decades, esp. in recent years.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjtlagtL4%253D&md5=c6ded2f09ac53af91e7f250db39c9fe9
3
For work on the combination of achiral Au(I) complexes and chiral anions, see the following:
(a) Reference (1).
Google Scholar
There is no corresponding record for this reference.
(b) LaLonde, R. L.; Wang, Z. J.; Mba, M.; Lackner, A. D.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Synthesis of Pyrazolidines, Isoxazolidines, and Tetrahydrooxazines. Angew. Chem., Int. Ed. 2010, 49, 598– 601, DOI: 10.1002/anie.200905000
Google Scholar
3b
Gold(I)-catalyzed enantioselective synthesis of pyrazolidines, isoxazolidines, and tetrahydrooxazines
Lalonde R L; Wang Z J; Mba M; Lackner A D; Toste F Dean
Angewandte Chemie (International ed. in English) (2010), 49 (3), 598-601 ISSN:.
There is no expanded citation for this reference.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3c%252FitVenuw%253D%253D&md5=b065f4ea0ac0716de82658c15be4a5ec
(c) Zi, W.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Desymmetrization of 1,3-Diols through Intramolecular Hydroalkoxylation of Allenes. Angew. Chem., Int. Ed. 2015, 54, 14447– 14451, DOI: 10.1002/anie.201508331
Google Scholar
3c
Gold(I)-Catalyzed Enantioselective Desymmetrization of 1,3-Diols through Intramolecular Hydroalkoxylation of Allenes
Zi, Weiwei; Toste, F. Dean
Angewandte Chemie, International Edition (2015), 54 (48), 14447-14451CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A gold(I)-catalyzed enantioselective desymmetrization of 1,3-diols was achieved by intramol. hydroalkoxylation of allenes. The catalyst system 3-F-dppe(AuCl)2/(R)-C8-TRIPAg proved to be specifically efficient to promote the desymmetrizing cyclization of 2-aryl-1,3-diols, which have proven challenging substrates in previous reports [e.g., diol I → THF II (>95% yield, d.r. > 25:1, ee 93%) in presence of L(AuCl2)/AgX*, where L = III and AgX* = IV]. Multisubstituted tetrahydrofurans were prepd. in good yield with good enantioselectivity and diastereoselectivity by this method.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsF2ksrbN&md5=fd955d1383ee88c56adf12d45bf28eb9
(d) Pedrazzani, R.; An, J.; Monari, M.; Bandini, M. New Chiral BINOL-Based Phosphates for Enantioselective [Au(I)]-Catalyzed Dearomatization of β-Naphthols with Allenamides. Eur. J. Org. Chem. 2021, 2021, 1732– 1736, DOI: 10.1002/ejoc.202100166
Google Scholar
3d
New Chiral BINOL-Based Phosphates for Enantioselective [Au(I)]-Catalyzed Dearomatization of β-Naphthols with Allenamides
Pedrazzani, Riccardo; An, Juzeng; Monari, Magda; Bandini, Marco
European Journal of Organic Chemistry (2021), 2021 (11), 1732-1736CODEN: EJOCFK; ISSN:1099-0690. (Wiley-VCH Verlag GmbH & Co. KGaA)
New chiral BINOL-based phosphate counterions have been synthesized, fully characterized, and employed in the enantioselective gold-catalyzed dearomatization of β-naphthols with allenamides. A range of densely functionalized C1-allylated naphthalenones were realized under mild conditions and high levels of chemo-, regio- and stereoselectivity (ee up to 95%).
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmvFGrtLs%253D&md5=c235fc472d5fc0aadc013ea7db5802de
4
For work on the combination of chiral Au(I) complexes and chiral anions, see the following:
(a) Aikawa, K.; Kojima, M.; Mikami, K. Axial Chirality Control of Gold(biphep) Complexes by Chiral Anions: Application to Asymmetric Catalysis. Angew. Chem., Int. Ed. 2009, 48, 6073– 6077, DOI: 10.1002/anie.200902084
Google Scholar
4a
Axial Chirality Control of Gold(biphep) Complexes by Chiral Anions: Application to Asymmetric Catalysis
Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
Angewandte Chemie, International Edition (2009), 48 (33), 6073-6077, S6073/1-S6073/47CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
The axial chirality of tropos gold-biphep (biphep = bis(phosphanyl)biphenyl) complexes can be controlled by chiral anions (S)-I (Ar = Ph; 4-PhC6H4; 2,4,6-tri-iPrC6H2; 2-naphthyl; etc.), and the chirality is imprinted and memorized even after the dissocn. of I. The enantiopure complexes thus obtained efficiently function as axially chiral asym. catalysts in an intramol. hydroamination reaction of (aminoalkyl)allene derivs. to yield enantiomerically enriched pyrrolidines.
>> More from SciFinder ^®
https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXptlCjt7k%253D&md5=89bd01f2ead534e211c313429db20eba
(b) Aikawa, K.; Kojima, M.; Mikami, K. Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions. Adv. Synth. Catal. 2010, 352, 3131– 3135, DOI: 10.1002/adsc.201000672
Google Scholar
4b
Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions
Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
Advanced Synthesis & Catalysis (2010), 352 (18), 3131-3135CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
A synergistic effect is obsd. for the combination of neutral dinuclear gold complex I (R1 = 3,5-di-MeC6H3) with chiral silver phosphate II in the intramol. hydroalkoxylation of allenes to give vinyltetrahydrofuran derivs. in high yields and enantioselectivities. The monocationic dinuclear gold complex affords higher catalytic activity and enantioselectivity than the neutral or dicationic digold complexes. The synergistic effect is thus highly promising to provide a guiding principle in designing an efficient chiral environment for creating an asym. catalyst.
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Corrigendum:Aikawa, K.; Kojima, M.; Mikami, K. Adv. Synth. Catal. 2011, 353, 2882– 2883, DOI: 10.1002/adsc.201100838
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Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions [Erratum to document cited in CA154:259297]
Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
Advanced Synthesis & Catalysis (2011), 353 (16), 2882-2883CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
Due to a stereochem. error, the article requires several configuration corrections; the cor. compds. are given.
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(c) Barreiro, E. M.; Broggini, D. F. D.; Adrio, L. A.; White, A. J. P.; Schwenk, R.; Togni, A.; Hii, K. K. Gold(I) Complexes of Conformationally Constricted Chiral Ferrocenyl Phosphines. Organometallics 2012, 31, 3745– 3754, DOI: 10.1021/om300222k
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4c
Gold(I) Complexes of Conformationally Constricted Chiral Ferrocenyl Phosphines
Barreiro, Elena M.; Broggini, Diego F. D.; Adrio, Luis A.; White, Andrew J. P.; Schwenk, Rino; Togni, Antonio; Hii, King Kuok
Organometallics (2012), 31 (9), 3745-3754CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
The prepn. of two new chiral, enantiopure, and conformationally constrained phosphocin and 1,5-diphosphocin, incorporating two ferrocenyl units, is described. The gold(I) chloride complexes of these ligands and (S)-(R)-PPF-OMe were prepd., and their structures, in soln. and solid states, are compared. Abstraction of the chloride anion by the addn. of silver salt of either toluenesulfonate or chiral BINOL-phosphates generates active catalysts for the intramol. cyclization of 6-methyl-1,1-diphenylhepta-4,5-dien-1-ol, where up to 47% ee can be obtained. Match and mismatch effects between chiral ligands and counteranions are highlighted.
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(d) Miles, D. H.; Veguillas, M.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Bromocyclization Reactions of Allenes. Chem. Sci. 2013, 4, 3427– 3431, DOI: 10.1039/c3sc50811k
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4d
Gold(I)-catalyzed enantioselective bromocyclization reactions of allenes
Miles, Dillon H.; Veguillas, Marcos; Toste, F. Dean
Chemical Science (2013), 4 (9), 3427-3431CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
The enantioselective bromocyclization of allenes, e.g. I, using chiral dinuclear gold complex and/or chiral phosphate anions in presence of N-bromolactam as an electrophilic bromine source was described. The enantioselective bromocyclization provides access to heterocyclic vinyl bromides with an allylic stereocenter in excellent yield and enantioselectivity. The synthesized enantio enriched vinyl bromides II may serve as a handle for further derivatization via cross-coupling reactions.
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(e) Handa, S.; Lippincott, D. J.; Aue, D. H.; Lipshutz, B. H. Asymmetric Gold-Catalyzed Lactonizations in Water at Room Temperature. Angew. Chem., Int. Ed. 2014, 53, 10658– 10662, DOI: 10.1002/anie.201404729
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4e
Asymmetric Gold-Catalyzed Lactonizations in Water at Room Temperature
Handa, Sachin; Lippincott, Daniel J.; Aue, Donald H.; Lipshutz, Bruce H.
Angewandte Chemie, International Edition (2014), 53 (40), 10658-10662CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
Asym. gold-catalyzed hydrocarboxylations are reported that show broad substrate scope. The hydrophobic effect assocd. with in situ-formed aq. nanomicelles gives good to excellent ee's of product lactones. In-flask product isolation, along with the recycling of the catalyst and the reaction medium, are combined to arrive at an esp. environmentally friendly process.
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(a) Mourad, A. K.; Leutzow, J.; Czekelius, C. Anion-Induced Enantioselective Cyclization of Diynamides to Pyrrolidines Catalyzed by Cationic Gold Complexes. Angew. Chem., Int. Ed. 2012, 51, 11149– 11152, DOI: 10.1002/anie.201205416
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5a
Anion-induced enantioselective cyclization of diynamides to pyrrolidines catalyzed by cationic gold complexes
Mourad, Asmaa Kamal; Leutzow, Juliane; Czekelius, Constantin
Angewandte Chemie, International Edition (2012), 51 (44), 11149-11152CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
An enantioselective synthesis of methylene pyrrolidines via cycloisomerization of 1,4-diynamides catalyzed by cationic gold complexes is developed. The reaction used cationic gold catalyst with optically active and binol phosphates as counteranions. The best results were obtained in chlorinated solvents at low temp.
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(b) Spittler, M.; Lutsenko, K.; Czekelius, C. Total Synthesis of (+)-Mesembrine Applying Asymmetric Gold Catalysis. J. Org. Chem. 2016, 81, 6100– 6105, DOI: 10.1021/acs.joc.6b00985
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5b
Total Synthesis of (+)-Mesembrine Applying Asymmetric Gold Catalysis
Spittler, Michael; Lutsenko, Kiril; Czekelius, Constantin
Journal of Organic Chemistry (2016), 81 (14), 6100-6105CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)
The total synthesis of enantiomerically pure (+)-mesembrine is described. The central pyrrolidine moiety incorporating a quaternary, all-carbon-substituted stereocenter was constructed employing an asym. gold-catalyzed cycloisomerization of a 1,4-diynamide.
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For a review on the combination of Au(I) methyl complexes and excess Brønsted acid for tandem reactions, see the following:
(a) Inamdar, S. M.; Konala, A.; Patil, N. T. When gold meets chiral Brønsted acid catalysis: extending the boundaries of enantioselective gold catalysis. Chem. Commun. 2014, 50, 15124– 15135, DOI: 10.1039/C4CC04633A
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6a
When gold meets chiral Bronsted acid catalysts: extending the boundaries of enantioselective gold catalysis
Inamdar, Suleman M.; Konala, Ashok; Patil, Nitin T.
Chemical Communications (Cambridge, United Kingdom) (2014), 50 (96), 15124-15135CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
A review; this review describes the development in the use of Au(I)/Bronsted acid binary catalytic systems to enable an enantioselective transformation in one-pot that cannot be achieved by gold catalysts alone. The examples discussed herein are promising since apart from using chiral ligands there exists a possibility of using chiral Bronsted acids. Clearly, the horizon for enantioselective gold catalysis has been expanded as more options to make the gold-catalyzed reactions enantioselective have become available.
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For selected examples, see the following:
(b) Han, Z.-Y.; Xiao, H.; Chen, X.-H.; Gong, L.-Z. Consecutive Intramolecular Hydroamination/Asymmetric Transfer Hydrogenation under Relay Catalysis of an Achiral Gold Complex/Chiral Brønsted Acid Binary System. J. Am. Chem. Soc. 2009, 131, 9182– 9183, DOI: 10.1021/ja903547q
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6b
Consecutive Intramolecular Hydroamination/Asymmetric Transfer Hydrogenation under Relay Catalysis of an Achiral Gold Complex/Chiral Bronsted Acid Binary System
Han, Zhi-Yong; Xiao, Han; Chen, Xiao-Hua; Gong, Liu-Zhu
Journal of the American Chemical Society (2009), 131 (26), 9182-9183CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Consecutive hydroamination/asym. transfer hydrogenation under relay catalysis of an achiral gold complex/chiral Bronsted acid binary system has been described for the direct transformation of 2-(2-propynyl)aniline derivs. into tetrahydroquinolines with high enantiomeric purity.
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(c) Muratore, M. E.; Holloway, C. A.; Pilling, A. W.; Storer, R. I.; Trevitt, G.; Dixon, D. J. Enantioselective Brønsted Acid-Catalyzed N-Acyliminium Cyclization Cascades. J. Am. Chem. Soc. 2009, 131, 10796– 10797, DOI: 10.1021/ja9024885
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6c
Enantioselective Bronsted Acid-Catalyzed N-Acyliminium Cyclization Cascades
Muratore, Michael E.; Holloway, Chloe A.; Pilling, Adam W.; Storer, R. Ian; Trevitt, Graham; Dixon, Darren J.
Journal of the American Chemical Society (2009), 131 (31), 10796-10797CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
An enantioselective Bronsted acid-catalyzed N-acyliminium cyclization cascade of tryptamines with enol lactones to form architecturally complex heterocycles, i.e. I, in high enantiomeric excess has been developed. The reaction is tech. simple to perform as well as atom-efficient and may be coupled to a gold(I)-catalyzed cycloisomerization of alkynoic acids whereby the key enol lactone reaction partner is generated in situ. Employing up to 10 mol % bulky chiral phosphoric acid catalysts in boiling toluene allowed the product materials to be generated in good overall yields (63-99%) and high enantioselectivities (72-99% ee). With doubly substituted enol lactones, high diastereo- and enantioselectivities were obtained, thus providing a new example of a dynamic kinetic asym. cyclization reaction.
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(d) Liu, X.-Y.; Che, C.-M. Highly Enantioselective Synthesis of Chiral Secondary Amines by Gold(I)/Chiral Brønsted Acid Catalyzed Tandem Intermolecular Hydroamination and Transfer Hydrogenation Reactions. Org. Lett. 2009, 11, 4204– 4207, DOI: 10.1021/ol901443b
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6d
Highly Enantioselective Synthesis of Chiral Secondary Amines by Gold(I)/Chiral Bronsted Acid Catalyzed Tandem Intermolecular Hydroamination and Transfer Hydrogenation Reactions
Liu, Xin-Yuan; Che, Chi-Ming
Organic Letters (2009), 11 (18), 4204-4207CODEN: ORLEF7; ISSN:1523-7060. (American Chemical Society)
A method for the synthesis of enantiomerically enriched secondary amines with excellent ee values through the tandem intermol. hydroamination/transfer hydrogenation of alkynes using a "gold(I) complex-chiral Bronsted acid" protocol is developed. The catalysis works for a wide variety of aryl, alkenyl, and aliph. alkynes as well as anilines with different electronic properties.
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(e) Tu, X.-F.; Gong, L.-Z. Highly Enantioselective Transfer Hydrogenation of Quinolines Catalyzed by Gold Phosphates: Achiral Ligand Tuning and Chiral-Anion Control of Stereoselectivity. Angew. Chem., Int. Ed. 2012, 51, 11346– 11349, DOI: 10.1002/anie.201204179
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6e
Highly Enantioselective Transfer Hydrogenation of Quinolines Catalyzed by Gold Phosphates: Achiral Ligand Tuning and Chiral-Anion Control of Stereoselectivity
Tu, Xi-Feng; Gong, Liu-Zhu
Angewandte Chemie, International Edition (2012), 51 (45), 11346-11349CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
The authors have found that chiral gold phosphate complexes are able to serve as highly efficient catalysts for the asym. transfer hydrogenation of 2-arylquinolines with the stereoselectivity being controlled by the chiral anion. Only 0.01 mol. % of the gold phosphate is needed to effectively afford the highly enantioselective transfer hydrogenation of 2-arylquinolines. Tuning of the achiral ligand IMes as in [IMesAuMe] had a great impact on the catalytic activity, with the chiral gold phosphate exhibiting high catalytic efficiency when the carbene IMes was used as a ligand.
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(f) Cala, L.; Mendoza, A.; Fañanás, F. J.; Rodríguez, F. A Catalytic Multicomponent Coupling Reaction for the Enantioselective Synthesis of Spiroacetals. Chem. Commun. 2013, 49, 2715– 2717, DOI: 10.1039/c3cc00118k
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6f
A catalytic multicomponent coupling reaction for the enantioselective synthesis of spiroacetals
Cala, Lara; Mendoza, Abraham; Fananas, Francisco J.; Rodriguez, Felix
Chemical Communications (Cambridge, United Kingdom) (2013), 49 (26), 2715-2717CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
The first multicomponent catalytic asym. synthesis of spiroacetals has been described. Hybrid mols. comprising a spiroacetal scaffold (a natural-product inspired scaffold) and an α-amino acid motif (a privileged fragment) are easily available through a gold phosphate-catalyzed one-pot three component coupling reaction of alkynols, anilines and glyoxylic acid.
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(g) Zhou, S.; Li, Y.; Liu, X.; Hu, W.; Ke, Z.; Xu, X. Enantioselective Oxidative Multi-Functionalization of Terminal Alkynes with Nitrones and Alcohols for Expeditious Assembly of Chiral α-Alkoxy-β-amino-ketones. J. Am. Chem. Soc. 2021, 143, 14703– 14711, DOI: 10.1021/jacs.1c06178
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6g
Enantioselective Oxidative Multi-Functionalization of Terminal Alkynes with Nitrones and Alcohols for Expeditious Assembly of Chiral α-Alkoxy-β-amino-ketones
Zhou, Su; Li, Yinwu; Liu, Xiangrong; Hu, Wenhao; Ke, Zhuofeng; Xu, Xinfang
Journal of the American Chemical Society (2021), 143 (36), 14703-14711CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Catalytic oxidative functionalization of alkynes has emerged as an effective method in synthetic chem. in recent decades. However, enantioselective transformations via metal carbene intermediates are quite rare due to the lack of robust chiral catalysts, esp. in the intermol. versions. Herein, the first asym. three-component reaction of com. available alkynes with nitrones and alcs., which affords α-alkoxy-β-amino-ketones in good yields with high to excellent enantioselectivity using combined catalysis by achiral gold-complex and chiral spiro phosphoric acid (CPA) is reported. Mechanistically, this atom-economic reaction involves a catalytic alkyne oxidn./ylide formation/Mannich-type addn. sequence that uses nitrone as the oxidant and the leaving fragment imine as the electrophile, providing a novel method for multifunctionalization of com. available terminal alkynes.
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(a) Dorel, R.; Echavarren, A. M. Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity. Chem. Rev. 2015, 115, 9028– 9072, DOI: 10.1021/cr500691k
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7a
Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity
Dorel, Ruth; Echavarren, Antonio M.
Chemical Reviews (Washington, DC, United States) (2015), 115 (17), 9028-9072CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. In this review, the authors cover reactions of alkynes activated by gold(I) complexes, including recent applications of these transformations in the synthesis of natural products. The main focus is on the application of gold(I)-catalyzed reactions of alkynes in org. synthesis, and the reactions are organized mechanistically. Reactions of gold(I)-activated alkenes and allenes, as well as gold(III)-activated alkynes, are not covered in this review.
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(b) Zuccarello, G.; Escofet, I.; Caniparoli, U.; Echavarren, A. M. New-Generation Ligand Design for the Gold Catalyzed Asymmetric Activation of Alkynes. ChemPlusChem 2021, 86, 1283– 1296, DOI: 10.1002/cplu.202100232
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7b
New-Generation Ligand Design for the Gold-Catalyzed Asymmetric Activation of Alkynes
Zuccarello, Giuseppe; Escofet, Imma; Caniparoli, Ulysse; Echavarren, Antonio M.
ChemPlusChem (2021), 86 (9), 1283-1296CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Herein the recent advances in intra- and intermol. enantioselective gold(I)-catalyzed reactions involving alkynes was summarized, discussing new chiral ligand designs that lie at the basis of these developments. The mode of action of these catalysts, their possible limitations towards a next-generation of more efficient ligand designs was discussed. Finally, square planar chiral gold(III) complexes, which offer an alternative to chiral gold(I) complexes, are also discussed.
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(c) Barbazanges, M.; Augé, M.; Moussa, J.; Amouri, H.; Aubert, C.; Desmarets, C.; Fensterbank, L.; Gandon, V.; Malacria, M.; Ollivier, C. Enantioselective Ir^I-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy. Chem.─Eur. J. 2011, 17, 13789– 13794, DOI: 10.1002/chem.201102723
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Enantioselective IrI-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy
Barbazanges, Marion; Auge, Mylene; Moussa, Jamal; Amouri, Hani; Aubert, Corinne; Desmarets, Christophe; Fensterbank, Louis; Gandon, Vincent; Malacria, Max; Ollivier, Cyril
Chemistry - A European Journal (2011), 17 (49), 13789-13794, S13789/1-S13789/71CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
Enantioenriched heterobicyclo[4.1.0]hept-2-enes were synthesized by IrI-catalyzed carbocyclization of 1,6-enynes. No chiral ligands were used; CO and PPh3 were the only ligands bound to iridium. Instead, the stereochem. information was localized on the counterion of the catalyst, generated in situ by reaction of Vaska's complex (trans-[IrCl(CO)(PPh3)2]) with a chiral silver phosphate. Enantiomeric excesses up to 93 % were obtained when this catalytic mixt. was used. 31P NMR and IR spectroscopy suggest that formation of the trans- [Ir(CO)(PPh3)2]+ moiety occurs by chlorine abstraction. Moreover, d. functional theory calcns. support a 6-endo-dig cyclization promoted by this cationic moiety. The chiral phosphate anion (O-P*) controls the enantioselectivity through formation of a loose ion pair with the metal center and establishes a C-H···O-P* hydrogen bond with the substrate. This is a rare example of asym. counterion-directed transition-metal catalysis and represents the first application of such a strategy to a C-C bond-forming reaction.
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Raducan, M.; Moreno, M.; Bour, C.; Echavarren, A. M. Phosphate Ligands in the Gold(I)-Catalysed Activation of Enynes. Chem. Commun. 2012, 48, 52– 54, DOI: 10.1039/C1CC15739F
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8
Phosphate ligands in the gold(I)-catalyzed activation of enynes
Raducan, Mihai; Moreno, Maria; Bour, Christophe; Echavarren, Antonio M.
Chemical Communications (Cambridge, United Kingdom) (2012), 48 (1), 52-54CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
Au(I) forms neutral complexes with binol phosphates, e.g., I (R = SiPh3, 2,4,6-iPr3C6H2), that are unreactive in the catalytic cyclization of enynes. However, reactions in protic solvents or with activation by Ag(I) restores the catalytic activity of, e.g., I.
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9
For reviews, see the following:
(a) Jia, M.; Bandini, M. Counterion Effects in Homogeneous Gold Catalysis. ACS Catal. 2015, 5, 1638– 1652, DOI: 10.1021/cs501902v
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9a
Counterion Effects in Homogeneous Gold Catalysis
Jia, Minqiang; Bandini, Marco
ACS Catalysis (2015), 5 (3), 1638-1652CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
A review. Homogeneous gold catalysis has received growing attention over the past few years, enabling the replacement of consolidated org. reactions with more simple, selective, and chem. sustainable alternatives. The fine-tunability of the electronic as well as steric properties of gold catalysts contributed substantially to the popularity of the research field, with robust applications in total synthesis and asym. catalysis. In this context, the metal counterions proved of pivotal importance in impacting both kinetics and selectivity of gold-assisted transformations. Despite the intrinsic difficulties in properly rationalizing and predicting the role of anions in complex reaction machineries, nowadays, some general trends are available. This review aims at presenting some leading examples of counterion-controlled gold catalysis, with particular emphasis on their structure-activity relationship.
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(b) Zuccaccia, D.; Del Zotto, A.; Baratta, W. The Pivotal Role of the Counterion in Gold Catalyzed Hydration and Alkoxylation of Alkynes. Coord. Chem. Rev. 2019, 396, 103– 116, DOI: 10.1016/j.ccr.2019.06.007
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9b
The pivotal role of the counterion in gold catalyzed hydration and alkoxylation of alkynes
Zuccaccia, D.; Del Zotto, A.; Baratta, W.
Coordination Chemistry Reviews (2019), 396 (), 103-116CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)
A review. Hydration and alkoxylation of alkynes are key processes for the industrial prodn. of carbonyl derivs. In this review, the pivotal role of ion pairing in the mechanism of hydration and alkoxylation of alkynes promoted by gold(I) catalysts L-Au-X is deeply analyzed and discussed, that has been elucidated by means of exptl. findings supported by some theor. calcns. In particular, the crucial role of the counterion X- is fully described in chapter 2. The catalytic performances in the alkoxylation and hydration of alkynes promoted by gold(I) are influenced by the coordination ability and basicity (proton affinity) of the counterion (paragraph 2.3) and the anion/cation relative orientation (paragraph 2.3). Also the appropriate matching of X- and the neutral ligand L must be taken into account to improve the catalytic performance of gold catalysts (paragraph 2.4). A survey of other non-covalent interactions, which however play a kinetic important role (hydrogen bonds, those triggered by suitable functionalities present on the ligand L, formation of supramol. catalytic systems or micelles, and others), is presented in chapter 3. The progress in the development of sustainable methodologies for the gold(I)-promoted hydration of alkynes is discussed in chapter 4. In particular, paragraph 4.1 focuses on the unique role played by the anion in the L-Au-X catalyzed hydration of alkynes conducted in solvent-, silver-, and acid-free conditions. To conclude this crit. review, in paragraph 4.2 it is highlighted how the amt. of ion pairing, combined with the presence of suitable functionalities in neoteric solvent, may allow the development of green protocols for gold(I) catalyzed hydration of alkynes.
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(c) Lu, Z.; Li, T.; Mudshinge, S. R.; Xu, B.; Hammond, G. B. Optimization of Catalysts and Conditions in Gold(I) Catalysis─Counterion and Additive Effects. Chem. Rev. 2021, 121, 8452– 8477, DOI: 10.1021/acs.chemrev.0c00713
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9c
Optimization of Catalysts and Conditions in Gold(I) Catalysis - Counterion and Additive Effects
Lu, Zhichao; Li, Tingting; Mudshinge, Sagar R.; Xu, Bo; Hammond, Gerald B.
Chemical Reviews (Washington, DC, United States) (2021), 121 (14), 8452-8477CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. Leading examples of counterion or additive-regulated gold catalysis from a mechanistic perspective were presented. Special attention to the phys. properties of counterion/additive, such as gold affinity and hydrogen bond basicity, and discuss their effects on the reactivity of gold catalysts were paid.
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For selected articles, see the following:
(a) Zuccaccia, D.; Belpassi, L.; Tarantelli, F.; Macchioni, A. Ion Pairing in Cationic Olefin-Gold(I) Complexes. J. Am. Chem. Soc. 2009, 131, 3170– 3171, DOI: 10.1021/ja809998y
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10a
Ion Pairing in Cationic Olefin-Gold(I) Complexes
Zuccaccia, Daniele; Belpassi, Leonardo; Tarantelli, Francesco; Macchioni, Alceo
Journal of the American Chemical Society (2009), 131 (9), 3170-3171CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
The relative anion-cation orientation in [(PPh3)Au(4-Me-styrene)]BF4 (1BF4) and [(NHC)Au(4-Me-styrene)]BF4 [2BF4; NHC = 1,3-bis(di-iso-propylphenyl)-imidazol-2-ylidene] was studied by combining 19F,1H-HOESY NMR spectroscopy and D. Functional Theory (DFT) calcns. incorporating solvent and relativistic effects. BF4- locates on the side of 4-Me-styrene, close to the olefin region that is opposite to the 4-Me-Ph moiety in 1BF4. In 2BF4, the counterion approaches the cation from the side of the NHC ligand and is mainly located close to the imidazole ring. In both cases, the counterion resides far away from the Au site, the latter carrying only a small fraction of the pos. charge. The preferential position of the counterion is tunable through the choice of the ancillary ligand, and this opens the way to greater control over the properties and activity of these catalysts.
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(b) Zuccaccia, D.; Belpassi, L.; Rocchigiani, L.; Tarantelli, F.; Macchioni, A. A Phosphine Gold(I) π-Alkyne Complex: Tuning the Metal-Alkyne Bond Character and Counterion Position by the Choice of the Ancillary Ligand. Inorg. Chem. 2010, 49, 3080– 3082, DOI: 10.1021/ic100093n
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10b
A phosphine gold(I) π-alkyne complex: tuning the metal-alkyne bond character and counterion position by the choice of the ancillary ligand
Zuccaccia, Daniele; Belpassi, Leonardo; Rocchigiani, Luca; Tarantelli, Francesco; Macchioni, Alceo
Inorganic Chemistry (2010), 49 (7), 3080-3082CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
Gold-alkyne bonding was investigated in dependence on an ancillary ligands, electron-deficient phosphine and 2-imidazolylidene NHC carbene, by NMR spectroscopy and DFT calcns. The intra- and interionic structures of a mononuclear phosphine gold(I) alkyne complex [(PArF3)Au(2-hexyne)]BF4 [1·BF4; ArF = 3,5-(CF3)2C6H3] and its analogous complex [(NHC)Au(2-hexyne)]BF4 [2·BF4; NHC = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene] have been investigated by combining 1D and 2D multinuclear NMR spectroscopy and d. functional theory calcns. It has been found that alkyne in 1·BF4 is depleted of its electron d. to a greater extent than that in 2·BF4. This correlates with the Δδ(13C) NMR of the carbon-carbon triple bond. Instead, 2·BF4 is much more kinetically stable than 1·BF4. NMR 19F-1H HOESY spectra indicate that the counterion locates close to the gold atom in 1·BF4 (differently from that previously obsd. in the few other gold(I) ion pairs studied), exactly where the computed Coulomb potential indicates that partial pos. charge accumulates.
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(c) Bandini, M.; Bottoni, A.; Chiarucci, M.; Cera, G.; Miscione, G. P. Mechanistic Insights into Enantioselective Gold-Catalyzed Allylation of Indoles with Alcohols: The Counterion Effect. J. Am. Chem. Soc. 2012, 134, 20690– 20700, DOI: 10.1021/ja3086774
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10c
Mechanistic Insights into Enantioselective Gold-Catalyzed Allylation of Indoles with Alcohols: The Counterion Effect
Bandini, Marco; Bottoni, Andrea; Chiarucci, Michel; Cera, Gianpiero; Miscione, Gian Pietro
Journal of the American Chemical Society (2012), 134 (51), 20690-20700CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Enantioselective gold-catalysis is emerging as a powerful tool in org. synthesis for the stereoselective manipulation of unfunctionalized unsatd. hydrocarbons. Despite the exponential growth, the mol. complexity of common chiral gold complexes generally prevents a complete description of the mechanism steps and activation modes being documented. In this study, we present the results of a combined exptl.-computational (DFT) investigation of the mechanism of the enantioselective gold-catalyzed allylic alkylation of indoles with alcs. A stepwise SN2'-process (i.e. anti-auroindolination of the olefin, proton-transfer, and subsequent anti-elimination [Au]-OH) is disclosed, leading to a library of tricyclic-fused indole derivs. The pivotal role played by the gold counterion, in terms of mol. arrangement (i.e. "folding effect") and proton-shuttling in restoring the catalytic species, is finally documented.
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(d) Zhdanko, A.; Maier, M. E. Explanation of Counterion Effects in Gold(I)-Catalyzed Hydroalkoxylation of Alkynes. ACS Catal. 2014, 4, 2770– 2775, DOI: 10.1021/cs500446d
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10d
Explanation of Counterion Effects in Gold(I)-Catalyzed Hydroalkoxylation of Alkynes
Zhdanko, Alexander; Maier, Martin E.
ACS Catalysis (2014), 4 (8), 2770-2775CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
Using gold(I)-catalyzed hydroalkoxylation of alkynes as a model reaction with a well-known mechanism, a systematic exptl. study was conducted to disclose the influence of the counterion X- of a gold catalyst LAuNCMe+ X- on every step of the catalytic cycle. The overall ion effect is detd. as a superposition of several effects, operating on different steps of the reaction mechanism. All effects were explained from a position of hydrogen bonding, coordination chem. at gold, and affinity for a proton.
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(e) Biasiolo, L.; Del Zotto, A.; Zuccaccia, D. Toward Optimizing the Performance of Homogeneous L-Au-X Catalysts through Appropriate Matching of the Ligand (L) and Counterion (X^–). Organometallics 2015, 34, 1759– 1765, DOI: 10.1021/acs.organomet.5b00308
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10e
Toward optimizing the performance of homogeneous L-Au-X catalysts through appropriate matching of the ligand (L) and counterion (X-)
Biasiolo, Luca; Del Zotto, Alessandro; Zuccaccia, Daniele
Organometallics (2015), 34 (9), 1759-1765CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
A set of 16 gold complexes of the type L-Au-X [L = PPh3, PtBu3, P[3,5-(CF3)2C6H3]3, 1,3-bis(2,6-diisopropylphenyl)-2-imidazolylidene (IPr); X = BF4-, OTf, OTs, CF3CO2] was prepd. and evaluated for their catalytic activity in cyclization of N-propargylbenzamide into 2-phenyl-5-methyleneoxazoline as a model for cycloisomerization of unsatd. amides into nitrogen heterocycles and methoxylation of 3-hexyne; the substituent effects were controlled by varying the electron withdrawing ability coordinating ability, basicity, and hydrogen bond acceptor power of the ligand and X groups. The effects of the ligand (L) and counterion (X-) are considered the two most important factors in homogeneous gold catalysis, but a rational understanding of their synergy/antagonism is still lacking. The main results are that the choice of the most efficient L-Au-X catalyst for a given process should not be made by evaluating the properties of L and X- alone, but rather based on their best combination. For NHC-Au-X, the noncoordinating and weakly basic anions (such as BF4- and OTf-) have been recognized as the best choice for the cycloisomerization of N-(propargyl)benzamide. On the other side, the intermediate coordinating ability and basicity of OTs- provide the best compromise for achieving an efficient methoxylation of 3-hexyne. A completely different trend is found in the case of complexes bearing phosphines: OTs- and TFA- have been found to accelerate the cycloisomerization of N-(propargyl)benzamide, and BF4- and OTf- are suitable for the methoxylation of 3-hexyne. A possible explanation of the obsd. differences between phosphine and NHC ancillary ligands might be found in the higher affinity of the counterion (esp. OTs-) for the gold fragment for phosphane instead of NHC.
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(f) Lu, Z.; Han, J.; Okoromoba, O. E.; Shimizu, N.; Amii, H.; Tormena, C. F.; Hammond, G. B.; Xu, B. Predicting Counterion Effects Using a Gold Affinity Index and a Hydrogen Bonding Basicity Index. Org. Lett. 2017, 19, 5848– 5851, DOI: 10.1021/acs.orglett.7b02829
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10f
Predicting Counterion Effects Using a Gold Affinity Index and a Hydrogen Bonding Basicity Index
Lu, Zhichao; Han, Junbin; Okoromoba, Otome E.; Shimizu, Naoto; Amii, Hideki; Tormena, Claudio F.; Hammond, Gerald B.; Xu, Bo
Organic Letters (2017), 19 (21), 5848-5851CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
We have developed a gold affinity index and hydrogen bonding basicity index for counterions and have used these indexes to forecast their reactivity in cationic gold catalysis.
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(g) Schießl, J.; Schulmeister, J.; Doppiu, A.; Wörner, E.; Rudolph, M.; Karch, R.; Hashmi, A. S. K. An Industrial Perspective on Counter Anions in Gold Catalysis: Underestimated with Respect to “Ligand Effects”. Adv. Synth. Catal. 2018, 360, 2493– 2502, DOI: 10.1002/adsc.201800233
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10g
An Industrial Perspective on Counter Anions in Gold Catalysis: Underestimated with Respect to "Ligand Effects"
Schiessl, Jasmin; Schulmeister, Juergen; Doppiu, Angelino; Woerner, Eileen; Rudolph, Matthias; Karch, Ralf; Hashmi, A. Stephen K.
Advanced Synthesis & Catalysis (2018), 360 (13), 2493-2502CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
The conversion of a variety of well-known test reactions, representing the key reactivity patterns of gold catalysis, were analyzed by GC and 1H NMR. The study is focused on establishing of a strategical approach for the consideration of ligand influence and counter anion influence during the catalyst optimization including an industrial perspective. The study shows a dominance of the counter anion, a dominance which up to now has been neglected in most of the routine screenings. In addn., a drastic substrate-dependency became obvious, even a marginal variation of the substrate already could strongly effect the catalytic activity and change the optimal counter anion or ligand. Based on the collected data a strategic concept for an efficient screening for a specific substrate is introduced, this concept can serve as an important guideline for catalyst optimization in homogeneous gold catalysis.
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(a) Neel, A. J.; Hilton, M. J.; Sigman, M. S.; Toste, F. D. Exploiting Non-covalent π Interactions for Catalyst Design. Nature 2017, 543, 637– 646, DOI: 10.1038/nature21701
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11a
Exploiting non-covalent π interactions for catalyst design
Neel, Andrew J.; Hilton, Margaret J.; Sigman, Matthew S.; Toste, F. Dean
Nature (London, United Kingdom) (2017), 543 (7647), 637-646CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
A review. Mol. recognition, binding, and catalysis are often mediated by non-covalent interactions involving arom. functional groups. Although the relative complexity of these so-called π interactions has made them challenging to study, theory and modeling have now reached the stage at which we can explain their phys. origins and obtain reliable insight into their effects on mol. binding and chem. transformations. This offers opportunities for the rational manipulation of these complex non-covalent interactions and their direct incorporation into the design of small-mol. catalysts and enzymes.
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(b) Fanourakis, A.; Docherty, P. J.; Chuentragool, P.; Phipps, R. J. Recent Developments in Enantioselective Transition Metal Catalysis Featuring Attractive Noncovalent Interactions between Ligand and Substrate. ACS Catal. 2020, 10, 10672– 10714, DOI: 10.1021/acscatal.0c02957
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11b
Recent Developments in enantioselective transition metal catalysis featuring attractive non-covalent interactions between ligand and substrate
Fanourakis, Alexander; Docherty, Philip J.; Chuentragool, Padon; Phipps, Robert J.
ACS Catalysis (2020), 10 (18), 10672-10714CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
A review. Enantioselective transition metal catalysis is an area very much at the forefront of contemporary synthetic research. The development of processes that enable the efficient synthesis of enantiopure compds. is of unquestionable importance to chemists working within the many diverse fields of the central science. Traditional approaches to solving this challenge have typically relied on leveraging repulsive steric interactions between chiral ligands and substrates in order to raise the energy of one of the diastereomeric transition states over the other. By contrast, this review examines an alternative tactic in which a set of attractive non-covalent interactions operating between transition metal ligands and substrates are used to control enantioselectivity. Examples where this creative approach has been successfully applied to render fundamental synthetic processes enantioselective are presented and discussed. In many of the cases examd., the ligand scaffold has been carefully designed to accommodate these attractive interactions while in others, the importance of the crit. interactions was only elucidated in subsequent computational and mechanistic studies. Through an exploration and discussion of several recent reports encompassing a wide range of reaction classes authors hope to inspire synthetic chemists to continue to develop asym. transformations based on this powerful concept.
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(a) Duarte, F.; Paton, R. S. Molecular Recognition in Asymmetric Counteranion Catalysis: Understanding Chiral Phosphate-Mediated Desymmetrization. J. Am. Chem. Soc. 2017, 139, 8886– 8896, DOI: 10.1021/jacs.7b02468
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12a
Molecular Recognition in Asymmetric Counteranion Catalysis: Understanding Chiral Phosphate-Mediated Desymmetrization
Duarte, Fernanda; Paton, Robert S.
Journal of the American Chemical Society (2017), 139 (26), 8886-8896CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
We describe the first theor. study of a landmark example of chiral anion phase-transfer catalysis: the enantioselective ring-opening of meso-aziridinium and episulfonium cations promoted by asym. counteranion-directed catalysis (ACDC). The mechanism of ion-pairing, ring-opening, and catalyst deactivation have been studied in the condensed phase with both classical and quantum methods using explicitly and implicitly solvated models. We find that the stability of chiral ion-pairs, a prerequisite for asym. catalysis, is dominated by electrostatic interactions at long range and by CH···O interactions at short range. The decisive role of solvent upon ion-pair formation and of nonbonding interactions upon enantioselectivity are quantified by complementary computational approaches. The major enantiomer is favored by a smaller distortion of the substrate, demonstrated by a distortion/interaction anal. Our computational results rationalize the stereoselectivity for several exptl. results and demonstrate a combined classical/quantum approach to perform realistic modeling of chiral counterion catalysis in soln.
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(b) Orlandi, M.; Coelho, J. A. S.; Hilton, M. J.; Toste, F. D.; Sigman, M. S. Parametrization of Non-covalent Interactions for Transition State Interrogation Applied to Asymmetric Catalysis. J. Am. Chem. Soc. 2017, 139, 6803– 6806, DOI: 10.1021/jacs.7b02311
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12b
Parametrization of Non-covalent Interactions for Transition State Interrogation Applied to Asymmetric Catalysis
Orlandi, Manuel; Coelho, Jaime A. S.; Hilton, Margaret J.; Toste, F. Dean; Sigman, Matthew S.
Journal of the American Chemical Society (2017), 139 (20), 6803-6806CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
The use of computed interaction energies and distances as parameters in multivariate correlations is introduced for postulating non-covalent interactions. This new class of descriptors affords multivariate correlations for two diverse catalytic systems with unique non-covalent interactions at the heart of each process. The presented methodol. is validated by directly connecting the non-covalent interactions defined through empirical data set analyses to the computationally derived transition states.
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(c) Shoja, A.; Reid, J. P. Computational Insights into Privileged Stereocontrolling Interactions Involving Chiral Phosphates and Iminium Intermediates. J. Am. Chem. Soc. 2021, 143, 7209– 7215, DOI: 10.1021/jacs.1c03829
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12c
Computational Insights into Privileged Stereocontrolling Interactions Involving Chiral Phosphates and Iminium Intermediates
Shoja, Ali; Reid, Jolene P.
Journal of the American Chemical Society (2021), 143 (18), 7209-7215CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
The precise design of a catalyst for a given reaction is extremely difficult, often requiring a significant empirical screening campaign to afford products in high yields and enantiomeric excess. Design becomes even more challenging if one requires a catalyst that performs well for a diverse range of substrates. Such "privileged" catalysts exist, but little is known why they operate so generally. We report the results of computations which show that when substrate and catalyst features are conserved between significantly different mechanistic regimes, similar modes of activation can be invoked. As a validating case study, we explored a Hantzsch ester hydrogenation of α,β-unsatd. iminiums involving BINOL-derived chiral phosphates and find they impart asym. induction in an analogous fashion to their acid counterpart. Specifically, DFT calcns. at the IEFPCM(1,4-dioxane)-B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level predicted enantioselectivity to be close to the exptl. value (82% ee calcd., 96% ee exptl.) and showed that the reaction proceeds via a transition state involving two hydrogen-bonding interactions from the iminium intermediate and nucleophile to the catalyst. These interactions lower the energy of the transition structure and provide extra rigidity to the system. This new model invokes "privileged" noncovalent interactions and leads to a new explanation for the enantioselectivity outcome, ultimately providing the basis for the development of general catalyst design principles and the translation of mechanistically disparate reaction profiles for the prediction of enantioselectivity outcomes using statistical models.
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Zhang, Z.; Smal, V.; Retailleau, P.; Voituriez, A.; Frison, G.; Marinetti, A.; Guinchard, X. Tethered Counterion-Directed Catalysis: Merging the Chiral Ion-Pairing and Bifunctional Ligand Strategies in Enantioselective Gold(I) Catalysis. J. Am. Chem. Soc. 2020, 142, 3797– 3805, DOI: 10.1021/jacs.9b11154
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Tethered Counterion-Directed Catalysis: Merging the Chiral Ion-pairing and Bifunctional Ligand Strategies in Enantioselective Gold(I) Catalysis
Zhang, Zhenhao; Smal, Vitalii; Retailleau, Pascal; Voituriez, Arnaud; Frison, Gilles; Marinetti, Angela; Guinchard, Xavier
Journal of the American Chemical Society (2020), 142 (8), 3797-3805CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Tethering a metal complex to its phosphate counterion via a phosphine ligand enables a new strategy in asym. counter anion-directed catalysis (ACDC). A straightforward, scalable synthetic route gives access to the gold(I) complex I of a chiral phosphine displaying a phosphoric acid function. The complex generates a catalytically active species with an unprecedented intramol. relationship between the cationic Au(I) center and the phosphate counterion. The benefits of tethering the two functions of the catalyst is demonstrated here in a tandem cycloisomerization/nucleophilic addn. reaction, by attaining high enantioselectivity levels (up to 97% ee) at a remarkable low 0.2 mol% catalyst loading. Remarkably the method is also compatible with a silver-free protocol.
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Michelet, V. Noble Metal-Catalyzed Enyne Cycloisomerizations and Related Reactions. Comprehensive Organic Synthesis, 2nd ed.; Elsevier, 2014; Vol. 5, pp 1483– 1536.
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15
For recent reviews on asymmetric gold catalysis, see the following:
(a) Zi, W.; Toste, F. D. Recent Advances in Enantioselective Gold Catalysis. Chem. Soc. Rev. 2016, 45, 4567– 4589, DOI: 10.1039/C5CS00929D
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15a
Recent advances in enantioselective gold catalysis
Zi, Weiwei; Dean Toste, F.
Chemical Society Reviews (2016), 45 (16), 4567-4589CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
Interest in homogeneous gold catalysis has undergone a marked increase. As strong yet air- and moisture-tolerant π-acids, cationic gold(I) complexes have been shown to catalyze diverse transformations of alkenes, alkynes and allenes, opening new opportunities for chem. synthesis. The development of efficient asym. variants is required in order to take full advantage of the preparative potential of these transformations. During the last few years, the chem. community has achieved tremendous success in the area. This review highlights the updated progress (2011-2015) in enantioselective gold catalysis. The discussion is classified according to the π-bonds activated by gold(I), in an order of alkynes, allenes and alkenes. Other gold activation modes, such as σ-Lewis acid catalyzed reactions and transformations of diazo compds. are also discussed.
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(b) Li, Y.; Li, W.; Zhang, J. Gold-Catalyzed Enantioselective Annulations. Chem.─Eur. J. 2017, 23, 467– 512, DOI: 10.1002/chem.201602822
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15b
Gold-Catalyzed Enantioselective Annulations
Li, Yangyan; Li, Wenbo; Zhang, Junliang
Chemistry - A European Journal (2017), 23 (3), 467-512CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. This review summarized the methods to construct chiral cyclic compds. by gold-catalyzed enantioselective annulations reported since 2005. The review was organized according to the general annulation types catalyzed by chiral gold complexes or chiral gold salts, which have four main types (cycloaddns., cyclizations of C-C multiple bonds with tethered nucleophiles, cycloisomerization or cyclization of enynes, and tandem annulations), as well as some other strategies. The general reaction mechanisms of each subcategory, key intermediates for some unusual transformations, and the application of several novel ligands and chiral goldsalts were also discussed.
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(c) Jiang, J.-J.; Wong, M.-K. Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis. Chem.─Asian J. 2021, 16, 364– 377, DOI: 10.1002/asia.202001375
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15c
Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis
Jiang, Jia-Jun; Wong, Man-Kin
Chemistry - An Asian Journal (2021), 16 (5), 364-377CODEN: CAAJBI; ISSN:1861-4728. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. This review summarizes newly developed gold-catalyzed enantioselective org. transformations and recent progress in ligand design (since 2016), organized according to different types of chiral ligands, including bisphosphine ligands, monophosphine ligands, phosphite-derived ligands, and N-heterocyclic carbene ligands for asym. gold(I) catalysis as well as heterocyclic carbene ligands and oxazoline ligands for asym. gold(III) catalysis.
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(d) Porcel García, S. Gold Catalyzed Asymmetric Transformations. IntechOpen, 2021; DOI: 10.5772/intechopen.97519 .
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(e) Reference (7b).
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16
(a) Cheng, X.; Zhang, L. Designed Bifunctional Ligands in Cooperative Homogeneous Gold Catalysis. CCS Chem. 2021, 3, 1989– 2002, DOI: 10.31635/ccschem.020.202000454
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16a
Designed bifunctional ligands in cooperative homogeneous gold catalysis
Cheng, Xinpeng; Zhang, Liming
CCS Chemistry (2021), 3 (1), 1989-2002CODEN: CCCHB2 ISSN:. (Chinese Chemical Society)
Over the past two decades, homogeneous gold catalysis has experienced exponential development and contributed a plethora of highly valuable synthetic methods to the synthetic toolbox. Metalligand cooperative catalysis is a versatile strategy for achieving highly efficient and/or novel catalysis but has seldom been explored in gold chem. This minireview summarizes the progress we have made in developing remotely functionalized biaryl-2-ylphosphine ligands and employing them in cooperative gold catalysis that achieves excellent catalytic efficiency or realizes previously unknown reactivities. This approach also provides new venues for implementing asym. gold catalysis.
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(b) Zuccarello, G.; Zanini, M.; Echavarren, A. M. Buchwald-Type Ligands on Gold(I) Catalysis. Isr. J. Chem. 2020, 60, 360– 372, DOI: 10.1002/ijch.201900179
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16b
Buchwald-Type Ligands on Gold(I) Catalysis
Zuccarello, Giuseppe; Zanini, Margherita; Echavarren, Antonio M.
Israel Journal of Chemistry (2020), 60 (3-4), 360-372CODEN: ISJCAT; ISSN:0021-2148. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. This review emphasizes how this privileged ligand class, as well as recent modifications on the biarylphosphine motive, have triggered the discovery of new reactivities in our research program. Finally, the introduction of chiral information on the ligand scaffold provides new solns. to the challenging gold(I)-catalyzed enantioselective transformations.
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17
(a) Schreiner, P. R. Metal-Free Organocatalysis through Explicit Hydrogen Bonding Interactions. Chem. Soc. Rev. 2003, 32, 289– 296, DOI: 10.1039/b107298f
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17a
Metal-free organocatalysis through explicit hydrogen bonding interactions
Schreiner, Peter R.
Chemical Society Reviews (2003), 32 (5), 289-296CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. The metal (ion)-free catalysis of org. reactions is a contemporary challenge that is just being taken up by chemists. Hence, this field is in its infancy and is briefly reviewed here, along with some rough guidelines and concepts for further catalyst development. Catalysis through explicit hydrogen bonding interactions offers attractive alternatives to metal (ion)-catalyzed reactions by combining supramol. recognition with chem. transformations in an environmentally benign fashion. Although the catalytic rate accelerations relative to uncatalyzed reactions are often considerably less than for the metal (ion)-catalyzed variants, this need not be a disadvantage. Also, owing to weaker enthalpic binding interactions, product inhibition is rarely a problem and hydrogen bond additives are truly catalytic, even in water. A review.
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(b) Doyle, A. G.; Jacobsen, E. N. Small-Molecule H-Bond Donors in Asymmetric Catalysis. Chem. Rev. 2007, 107, 5713– 5743, DOI: 10.1021/cr068373r
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17b
Small-Molecule H-Bond Donors in Asymmetric Catalysis
Doyle, Abigail G.; Jacobsen, Eric N.
Chemical Reviews (Washington, DC, United States) (2007), 107 (12), 5713-5743CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review of asym. synthesis using small-mol. chiral hydrogen-bond donor catalysts in enantioselective addn. reactions to carbonyl, nitroalkene, α,β-unsatd. carbonyl, imine, and iminium ion electrophiles.
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18
For the only previous examples of phosphino(thio)urea Au(I) complexes, see the following:
(a) Campbell, M. J.; Toste, F. D. Enantioselective Synthesis of Cyclic Carbamimidates via a Three-Component Reaction of Imines, Terminal Alkynes, and p-Toluenesulfonylisocyanate Using a Monophosphine Gold(I) Catalyst. Chem. Sci. 2011, 2, 1369– 1378, DOI: 10.1039/c1sc00160d
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18a
Enantioselective synthesis of cyclic carbamimidates via a three-component reaction of imines, terminal alkynes, and p-toluenesulfonylisocyanate using a monophosphine gold(i) catalyst
Campbell, Matthew J.; Toste, F. Dean
Chemical Science (2011), 2 (7), 1369-1378CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
A racemic gold(I)-catalyzed three-component reaction was developed to prep. cyclic carbamimidates from imines, terminal alkynes and sulfonyl isocyanates. This reaction exploits the carbophilic π-acidity of gold catalysts to first activate an alkyne toward deprotonation and secondly, to activate the internal alkyne generated toward intramol. O-cyclization. Unlike similar previously reported multicomponent gold-catalyzed reactions, the stereocenter generated during the alkynylation is preserved in the product. This trait was exploited by developing an enantioselective variant, using an unusual trans-1-diphenylphosphino-2-arylsulfamidocyclohexane ligand, moderate to excellent levels of enantioselectivity were obtained using a variety of N-(aryl)benzylidene aniline derivs. and the synthesis of the target compds. was achieved in 41-95% enantiomeric excess (18 examples).
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(b) Franchino, A.; Martí, À.; Nejrotti, S.; Echavarren, A. M. Silver-Free Au(I) Catalysis Enabled by Bifunctional Urea- and Squaramide-Phosphine Ligands via H-Bonding. Chem.─Eur. J. 2021, 27, 11989– 11996, DOI: 10.1002/chem.202101751
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18b
Silver-Free Au(I) Catalysis Enabled by Bifunctional Urea- and Squaramide-Phosphine Ligands via H-Bonding
Franchino, Allegra; Marti, Alex; Nejrotti, Stefano; Echavarren, Antonio M.
Chemistry - A European Journal (2021), 27 (46), 11989-11996CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
A library of gold(I) chloride complexes I and II [R = H, CF3; Ar = Ph, 3,5-(CF3)2C6H3; X = CH2, (CH2)2, (CH2)3; Y = O, S] with phosphine ligands incorporating pendant (thio)urea and squaramide H-bond donors was prepd. with the aim of promoting chloride abstraction from Au(I) via H-bonding. In the absence of silver additives, complexes bearing squaramides and trifluoromethylated arom. ureas displayed good catalytic activity in the cyclization of N-propargyl benzamides, as well as in a 1,6-enyne cycloisomerization, a tandem cyclization-indole addn. reaction and the hydrohydrazination of phenylacetylene. Kinetic studies and DFT calcns. indicate that the energetic span of the reaction is accounted by both the chloride abstraction step, facilitated by the bidentate H-bond donor via an associative mechanism, and the subsequent cyclization step.
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19
(a) Akiyama, T. Stronger Brønsted Acids. Chem. Rev. 2007, 107, 5744– 5758, DOI: 10.1021/cr068374j
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19a
Stronger Bronsted Acids
Akiyama, Takahiko
Chemical Reviews (Washington, DC, United States) (2007), 107 (12), 5744-5758CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. The application of Bronsted acids as catalysts in various reactions is discussed in detail.
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(b) Terada, M. Binaphthol-derived Phosphoric Acid as a Versatile Catalyst for Enantioselective Carbon-Carbon Bond Forming Reactions. Chem. Commun. 2008, 4097– 4112, DOI: 10.1039/b807577h
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19b
Binaphthol-derived phosphoric acid as a versatile catalyst for enantioselective carbon-carbon bond forming reactions
Terada, Masahiro
Chemical Communications (Cambridge, United Kingdom) (2008), (35), 4097-4112CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
A review. Binaphthol-derived monophosphoric acids have been designed as novel chiral Bronsted-acid catalysts. The chiral phosphoric acids thus developed function as efficient enantioselective catalysts for a variety of org. transformations, esp. for carbon-carbon bond forming reactions.
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(c) Akiyama, T.; Mori, K. Stronger Brønsted Acids: Recent Progress. Chem. Rev. 2015, 115, 9277– 9306, DOI: 10.1021/acs.chemrev.5b00041
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19c
Stronger Bronsted Acids: Recent Progress
Akiyama, Takahiko; Mori, Keiji
Chemical Reviews (Washington, DC, United States) (2015), 115 (17), 9277-9306CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. The synthetic utility of Bronsted acid as a catalyst for the C-C bond formation reaction has seen significant growth in the 21st century, and a range of stronger Bronsted-acid-catalyzed reactions have been developed. Strong Bronsted acids, such as TfOH and Tf2NH, efficiently activated carbonyl groups, alkenes, alkynes, in addn. to hydroxy groups. They sometimes functioned complementarily to Lewis-acid catalysts. Chiral Bronsted acid has become one of the most attractive subjects in organocatalysis in the past decade because of the versatility for a wide range of reactions. In addn. to the chiral phosphoric acids, chiral dicarboxylic acids, chiral disulfonic acids, and chiral sulfonimides have emerged as stronger Bronsted acids, and their synthetic utility has gained wide acceptance.
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(d) Parmar, D.; Sugiono, E.; Raja, S.; Rueping, M. Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates. Chem. Rev. 2014, 114, 9047– 9153, DOI: 10.1021/cr5001496
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19d
Complete Field Guide to Asymmetric BINOL-Phosphate Derived Bronsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Bronsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates
Parmar, Dixit; Sugiono, Erli; Raja, Sadiya; Rueping, Magnus
Chemical Reviews (Washington, DC, United States) (2014), 114 (18), 9047-9153CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. Chiral BINOL-derived Broensted acids have shown themselves to be highly efficient catalysts for a huge plethora of transformations and allow the end user to form C-C, C-H, and a variety of C-X bonds in a highly enantioselective fashion. Although within this category phosphoric acids are strongly known for activating imine substrates, stronger acids in the form of N-triflyl phosphoramides have bridged the gap somewhat to accessing previously thought out-of-reach substrates. Their utility in synthesis however is not solely limited to their acidic character, and more recently they have become extremely powerful chiral counterions for an increasing list of reactions. Furthermore, they can be combined with metal catalysts to create a synergistic effect, which has opened new reaction modes previously not possible with the individual catalysts themselves. Improved understanding of the mechanisms and interactions assocd. between the catalyst and the substrates has allowed research groups to develop highly powerful methodologies. Unfortunately, our understanding is still far from complete, and currently we have a crude understanding of how the catalysts function, but detailed exptl. and computational studies are still required for further progress in the field.
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Correction:Parmar, D.; Sugiono, E.; Raja, S.; Rueping, M. Chem. Rev. 2017, 117, 10608– 10620, DOI: 10.1021/acs.chemrev.7b00197
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Addition and Correction to Complete Field Guide to Asymmetric BINOL-Phosphate Derived Bronsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Bronsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates [Erratum to document cited in CA161:504781]
Parmar, Dixit; Sugiono, Erli; Raja, Sadiya; Rueping, Magnus
Chemical Reviews (Washington, DC, United States) (2017), 117 (15), 10608-10620CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review.
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Wang, Y.; Wang, Z.; Li, Y.; Wu, G.; Cao, Z.; Zhang, L. A General Ligand Design for Gold Catalysis Allowing Ligand-Directed anti-Nucleophilic Attack of Alkynes. Nat. Commun. 2014, 5, 3470, DOI: 10.1038/ncomms4470
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20
A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes
Wang Yanzhao; Wang Zhixun; Wu Gongde; Cao Zheng; Zhang Liming; Li Yuxue
Nature communications (2014), 5 (), 3470 ISSN:.
Most homogenous gold catalyses demand ≥ 0.5 mol% catalyst loading. Owing to the high cost of gold, these reactions are unlikely to be applicable in medium- or large-scale applications. Here we disclose a novel ligand design based on the privileged (1,1'-biphenyl)-2-ylphosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3'-position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogenous gold catalysis considering the spatial challenge of using ligand to reach anti-approaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalysing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding.
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21
(a) Zhang, Z.; Schreiner, P. R. (Thio)urea Organocatalysis─What Can Be Learnt from Anion Recognition?. Chem. Soc. Rev. 2009, 38, 1187– 1198, DOI: 10.1039/b801793j
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21a
(Thio)urea organocatalysis - What can be learnt from anion recognition?
Zhang, Zhiguo; Schreiner, Peter R.
Chemical Society Reviews (2009), 38 (4), 1187-1198CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. The present crit. review outlines the close relationship and mutual interplay between mol. recognition, active site considerations in enzyme catalysis involving anions, and organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea organocatalysis. Indeed, the concepts of anion binding or binding with neg. (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 refs.).
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(b) Amendola, V.; Fabbrizzi, L.; Mosca, L. Anion Recognition by Hydrogen Bonding: Urea-Based Receptors. Chem. Soc. Rev. 2010, 39, 3889– 3915, DOI: 10.1039/b822552b
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21b
Anion recognition by hydrogen bonding: Urea-based receptors
Amendola, Valeria; Fabbrizzi, Luigi; Mosca, Lorenzo
Chemical Society Reviews (2010), 39 (10), 3889-3915CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. Since 1992 a variety of urea-based anion receptors were synthesized, of varying complexity and sophistication. This crit. review will focus on some distinctive aspects of anion recognition by urea derivs., with a special ref. to: (i) design and synthesis, (ii) methodologies for the investigation of the receptor-anion interaction in soln., (iii) the interpretation of the soln. behavior on the basis of the structural interplay between the receptor and the anion. The efficiency of urea as a receptor subunit depends on the presence of two proximate polarized N-H fragments, capable (i) of chelating a spherical anion or (ii) of donating two parallel H-bonds to the oxygen atoms of a carboxylate or of an inorg. oxoanion, a property which is shared with other diamides, e.g. squaramide. The wide use of urea in the design of neutral anion receptors seems to depends on the ease of its synthesis, in particular through the reaction of a primary amine group with an isocyanate, which allows the high-yield prepn. of sym. and unsym. substituted derivs. (83 refs.).
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(c) Bregović, V. B.; Basarić, N.; Mlinarić-Majerski, K. Anion Binding with Urea and Thiourea Derivatives. Coord. Chem. Rev. 2015, 295, 80– 124, DOI: 10.1016/j.ccr.2015.03.011
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22
For reviews on supramolecular ligands for asymmetric metal catalysis, see the following:
(a) Meeuwissen, J.; Reek, J. N. H. Supramolecular Catalysis Beyond Enzyme Mimics. Nat. Chem. 2010, 2, 615– 621, DOI: 10.1038/nchem.744
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22a
Supramolecular catalysis beyond enzyme mimics
Meeuwissen, Jurjen; Reek, Joost N. H.
Nature Chemistry (2010), 2 (8), 615-621CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
A review; supramol. catalysis - the assembly of catalyst species by harnessing multiple weak intramol. interactions - has, until recently, been dominated by enzyme-inspired approaches. Such approaches often attempt to create an enzyme-like 'active site' and have concd. on reactions similar to those catalyzed by enzymes themselves. Here, we discuss the application of supramol. assembly to the more traditional transition metal catalysis and to small-mol. organocatalysis. The modularity of self-assembled multicomponent catalysts means that a relatively small pool of catalyst components can provide rapid access to a large no. of catalysts that can be evaluated for industrially relevant reactions. In addn., we discuss how catalyst-substrate interactions can be tailored to direct substrates along particular reaction paths and selectivities.
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(b) Carboni, S.; Gennari, C.; Pignataro, L.; Piarulli, U. Supramolecular Ligand-Ligand and Ligand-Substrate Interactions for Highly Selective Transition Metal Catalysis. Dalton Trans. 2011, 40, 4355– 4373, DOI: 10.1039/c0dt01517b
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22b
Supramolecular ligand-ligand and ligand-substrate interactions for highly selective transition metal catalysis
Carboni, Stefano; Gennari, Cesare; Pignataro, Luca; Piarulli, Umberto
Dalton Transactions (2011), 40 (17), 4355-4373CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)
A review. The use of non covalent supramol. ligand-ligand and ligand-substrate interactions in transition metal-catalyzed transformations is a new, rapidly emerging area of research. Noncovalent interactions between monodentate ligands such as hydrogen bonding, coordinative bonding, ion pairing, π-π interactions and the formation of inclusion compds., impart higher activity and chemo-, regio-, and stereoselectivity to the corresponding transition metal complexes in a no. of catalytic applications. Analogously, supramol. ligand-substrate interactions, and particularly hydrogen bonding, were used to direct the regio- and stereochem. of several metal-catalyzed reactions. The catalytic systems relying on supramol. interactions are generally capable of self-assembling from simpler components in the environment where catalysis is to take place, and are therefore very well-suited for combinatorial catalyst discovery strategies and high-throughput screening.
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(c) Bellini, R.; van der Vlugt, J. I.; Reek, J. N. H. Supramolecular Self-Assembled Ligands in Asymmetric Transition Metal Catalysis. Isr. J. Chem. 2012, 52, 613– 629, DOI: 10.1002/ijch.201200002
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22c
Supramolecular self-assembled ligands in asymmetric transition metal catalysis
Bellini, Rosalba; van der Vlugt, Jarl Ivar; Reek, Joost N. H.
Israel Journal of Chemistry (2012), 52 (7), 613-629CODEN: ISJCAT; ISSN:0021-2148. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review was given on the progress in asym. transition metal catalysis using supramol. self-assembled ligands. The design of novel chiral ligands is at the core of asym. catalysis. The catalytic characteristics of a transition metal catalyst such as activity, selectivity and stability can be fine-tuned by optimization of the steric and electronic properties of the coordinating ligands. In asym. transformations, catalyst optimization still relies to a large extent on trial-and-error and educated guesses. New strategies based on combinatorial screening and high-throughput experimentation have been introduced for the design and optimization of new ligands and catalytic systems. Supramol. bidentate ligands that form by self-assembly of building blocks are particularly suited for this combinatorial approach as the potential no. of catalysts grows exponentially with the no. of building blocks synthesized. Catalytic systems based on supramol. interactions have proven to be highly advantageous in creating large ligand libraries for high-throughput screening, which allows optimization of activity and selectivity for a variety of reactions.
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(d) Raynal, M.; Ballester, P.; Vidal-Ferran, A.; van Leeuwen, P. W. N. M. Supramolecular Catalysis. Part 1: Non-Covalent Interactions as a Tool for Building and Modifying Homogeneous Catalysts. Chem. Soc. Rev. 2014, 43, 1660– 1733, DOI: 10.1039/C3CS60027K
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22d
Supramolecular catalysis. Part 1: non-covalent interactions as a tool for building and modifying homogeneous catalysts
Raynal, Matthieu; Ballester, Pablo; Vidal-Ferran, Anton; van Leeuwen, Piet W. N. M.
Chemical Society Reviews (2014), 43 (5), 1660-1733CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review; supramol. catalysis is a rapidly expanding discipline which has benefited from the development of both homogeneous catalysis and supramol. chem. The properties of classical metal and org. catalysts can now be carefully tailored by means of several suitable approaches and the choice of reversible interactions such as hydrogen bond, metal-ligand, electrostatic and hydrophobic interactions. The first part of these two subsequent reviews will be dedicated to catalytic systems for which non-covalent interactions between the partners of the reaction have been designed although mimicking enzyme properties has not been intended. Ligand, metal, organocatalyst, substrate, additive, and metal counterion are reaction partners that can be held together by non-covalent interactions. The resulting catalysts possess unique properties compared to analogs lacking the assembling properties. Depending on the nature of the reaction partners involved in the interactions, distinct applications have been accomplished, mainly (i) the building of bidentate ligand libraries (intra ligand-ligand), (ii) the building of di- or oligonuclear complexes (inter ligand-ligand), (iii) the alteration of the coordination spheres of a metal catalyst (ligand-ligand additive), and (iv) the control of the substrate reactivity (catalyst-substrate). More complex systems that involve the cooperative action of three reaction partners have also been disclosed. In this review, special attention will be given to supramol. catalysts for which the obsd. catalytic activity and/or selectivity have been imputed to non-covalent interaction between the reaction partners. Addnl. features of these catalysts are the easy modulation of the catalytic performance by modifying one of their building blocks and the development of new catalytic pathways/reactions not achievable with classical covalent catalysts.
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(e) Ohmatsu, K.; Ooi, T. Design of Supramolecular Chiral Ligands for Asymmetric Metal Catalysis. Tetrahedron Lett. 2015, 56, 2043– 2048, DOI: 10.1016/j.tetlet.2015.02.096
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22e
Design of supramolecular chiral ligands for asymmetric metal catalysis
Ohmatsu, Kohsuke; Ooi, Takashi
Tetrahedron Letters (2015), 56 (16), 2043-2048CODEN: TELEAY; ISSN:0040-4039. (Elsevier Ltd.)
A review. Three strategies for the development of supramol. chiral ligands for asym. metal catalysis are outlined. The basic ideas, advantages, and examples of each strategy are described.
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(f) Trouvé, J.; Gramage-Doria, R. Beyond Hydrogen Bonding: Recent Trends of Outer Sphere Interactions in Transition Metal Catalysis. Chem. Soc. Rev. 2021, 50, 3565– 3584, DOI: 10.1039/D0CS01339K
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22f
Beyond hydrogen bonding: recent trends of outer sphere interactions in transition metal catalysis
Trouve, Jonathan; Gramage-Doria, Rafael
Chemical Society Reviews (2021), 50 (5), 3565-3584CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
A review. Homogeneous catalytic reactions are typically controlled by the stereoelectronic nature of the ligand(s) that bind to the metal(s). The advantages of the so-called first coordination sphere effects have been used for the efficient synthesis of fine chems. relevant for industrial and academic labs. since more than half a century. Such level of catalyst control has significantly upgraded in the last few decades by mastering addnl. interactions beyond the first coordination sphere. These so-called second coordination sphere effects are mainly inspired by the action mode of nature's catalysts, enzymes, and, in general, rely on subtle hydrogen bonding for the exquisite control of activity and selectivity. In order to span the scope of this powerful strategy to challenges that cannot be solved purely by hydrogen bonding, a variety of less common interactions have been successfully introduced in the last few years for a fine chem. synthesis. This review covers the latest and most exciting developments of this newly flourishing area with a particular focus on highlighting how these types of interactions can be rationally implemented to control the reactivity in a remote fashion, which is far away from the active site similar to what enzymes also do.
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For a seminal example involving ion-pairing interactions between an achiral ligand and a chiral anion, see the following:
(g) Ohmatsu, K.; Ito, M.; Kunieda, T.; Ooi, T. Ion-Paired Chiral Ligands for Asymmetric Palladium Catalysis. Nat. Chem. 2012, 4, 473– 477, DOI: 10.1038/nchem.1311
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22g
Ion-paired chiral ligands for asymmetric palladium catalysis
Ohmatsu, Kohsuke; Ito, Mitsunori; Kunieda, Tomoatsu; Ooi, Takashi
Nature Chemistry (2012), 4 (6), 473-477CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
Conventional chiral ligands rely on the use of a covalently constructed, single chiral mol. embedded with coordinative functional groups. Here, the authors report a new strategy for the design of a chiral ligand for asym. transition-metal catalysis; approach is based on the development of an achiral cationic ammonium-phosphine hybrid ligand paired with a chiral binaphtholate anion. This ion-paired chiral ligand imparts a remarkable stereocontrolling ability to its palladium complex, which catalyzes a highly enantioselective allylic alkylation of α-nitro carboxylates. By exploiting the possible combinations of the achiral onium entities with suitable coordinative functionalities and readily available chiral acids, this approach should contribute to the development of a broad range of metal-catalyzed, stereoselective chem. transformations.
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Murata, M.; Buchwald, S. L. A General and Efficient Method for the Palladium-Catalyzed Cross-Coupling of Thiols and Secondary Phosphines. Tetrahedron 2004, 60, 7397– 7403, DOI: 10.1016/j.tet.2004.05.044
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A general and efficient method for the palladium-catalyzed cross-coupling of thiols and secondary phosphines
Murata, Miki; Buchwald, Stephen L.
Tetrahedron (2004), 60 (34), 7397-7403CODEN: TETRAB; ISSN:0040-4020. (Elsevier B.V.)
The general and efficient cross-coupling of thiols with aryl halides was developed utilizing Pd(OAc)2/1,1'-bis(diisopropylphosphino)ferrocene as the catalyst. The substrate scope was broad and included a variety of aryl bromides and chlorides, which can be coupled to aliph. and arom. thiols. The present catalyst system also enabled the palladium-catalyzed coupling of secondary phosphines with aryl bromides and chlorides.
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Luchini, G.; Ascough, D. M. H.; Alegre-Requena, J. V.; Gouverneur, V.; Paton, R. S. Data-Mining the Diaryl(thio)urea Conformational Landscape: Understanding the Contrasting Behavior of Ureas and Thioureas with Quantum Chemistry. Tetrahedron 2019, 75, 697– 702, DOI: 10.1016/j.tet.2018.12.033
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Data-mining the diaryl(thio)urea conformational landscape and Understanding the contrasting behavior of ureas and thioureas with quantum chemistry
Luchini, Guilian; Ascough, David M. H.; Alegre-Requena, Juan V.; Gouverneur, Veronique; Paton, Robert S.
Tetrahedron (2019), 75 (6), 697-702CODEN: TETRAB; ISSN:0040-4020. (Elsevier Ltd.)
The conformations adopted by urea and thiourea functional groups influence catalysis and binding. We combine data-mining with quantum chem. calcns. to understand the differences in conformational behavior for these two important structural motifs. We developed a Python tool to automate the compilation of X-ray structural information and perform conformational clustering and visualization, based on SMILES input. While diarylureas have an overwhelming preference for the anti,anti-conformer, diarylthioureas adopt a mixt. of anti,anti- and anti,syn-conformers. Computations show the anti,anti-thiourea conformer is destabilized by out-of-plane rotations which avoid a steric clash with the sulfur atom. These conformational preferences were studied computationally under a variety of conditions, and apart from in the gas-phase, a preference for anti,anti-ureas was found. Consistent with expts., this preference increases in more polar environments. Quant. predicted ratios are sensitive to the computational treatment of solvation effects, with COSMO-RS giving more realistic amts. of the anti,anti-conformer in THF and DMSO.
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Nakashima, D.; Yamamoto, H. Design of Chiral N-Triflyl Phosphoramide as a Strong Chiral Brønsted Acid and Its Application to Asymmetric Diels-Alder Reaction. J. Am. Chem. Soc. 2006, 128, 9626– 9627, DOI: 10.1021/ja062508t
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Design of Chiral N-Triflyl Phosphoramide as a Strong Chiral Bronsted Acid and Its Application to Asymmetric Diels-Alder Reaction
Nakashima, Daisuke; Yamamoto, Hisashi
Journal of the American Chemical Society (2006), 128 (30), 9626-9627CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
A highly reactive and acidic chiral Bronsted acid catalyst, chiral BINOL N-triflyl phosphoramide, was developed. Highly enantioselective Diels-Alder reaction of α,β-unsatd. ketone with silyloxydiene was demonstrated using this chiral Bronsted acid catalyst.
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(a) Nieto-Oberhuber, C.; López, S.; Echavarren, A. M. Intramolecular [4 + 2] Cycloadditions of 1,3-Enynes or Arylalkynes with Alkenes with Highly Reactive Cationic Phosphine Au(I) Complexes. J. Am. Chem. Soc. 2005, 127, 6178– 6179, DOI: 10.1021/ja042257t
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26a
Intramolecular [4+2] cycloadditions of 1,3-enynes or arylalkynes with alkenes with highly reactive cationic phosphine Au(I) complexes
Nieto-Oberhuber, Cristina; Lopez, Salome; Echavarren, Antonio M.
Journal of the American Chemical Society (2005), 127 (17), 6178-6179CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
New Au(I) complexes with bulky, biphenyl phosphines are the most reactive catalysts for the cyclizations of enynes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Nazarov-type ring expansion. 1,8-Dien-3-ynes also cyclize by a 5-exo-dig pathway to form hydrindanes. While thermal intramol. [4+2] cycloaddn. reactions (dehydro Diels-Alder reactions) of enynes with alkenes take place at high temps., the transformations reported here proceed with gold(I) catalysts and provide bicyclic or tricyclic ring systems.
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(b) Nieto-Oberhuber, C.; Pérez-Galán, P.; Herrero-Gómez, E.; Lauterbach, T.; Rodríguez, C.; López, S.; Bour, C.; Rosellón, A.; Cárdenas, D. J.; Echavarren, A. M. Gold(I)-Catalyzed Intramolecular [4 + 2] Cycloadditions of Arylalkynes or 1,3-Enynes with Alkenes: Scope and Mechanism. J. Am. Chem. Soc. 2008, 130, 269– 279, DOI: 10.1021/ja075794x
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26b
Gold(I)-Catalyzed Intramolecular [4+2] Cycloadditions of Arylalkynes or 1,3-Enynes with Alkenes: Scope and Mechanism
Nieto-Oberhuber, Cristina; Perez-Galan, Patricia; Herrero-Gomez, Elena; Lauterbach, Thorsten; Rodriguez, Cristina; Lopez, Salome; Bour, Christophe; Rosellon, Antonio; Cardenas, Diego J.; Echavarren, Antonio M.
Journal of the American Chemical Society (2008), 130 (1), 269-279CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
The cyclizations of enynes substituted at the alkyne gives products of formal [4+2] cyclization with Au(I) catalysts. 1,8-Dien-3-ynes cyclize by a 5-exo-dig pathway to form hydrindanes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Friedel-Crafts-type ring expansion. A 6-endo-dig cyclization is also obsd. in some cases as a minor process, although in a few cases, this is the major cyclization pathway. In addn. to cationic gold complexes bearing bulky biphenyl phosphines, a gold complex with tris(2,6-di-tert-butylphenyl)phosphite is exceptionally reactive as a catalyst for this reaction. This cyclization can also be carried out very efficiently with heating under microwave irradn. DFT calcns. support a stepwise mechanism for the cycloaddn. by the initial formation of an anti-cyclopropyl gold(I)-carbene, followed by its opening to form a carbocation stabilized by a π interaction with the aryl ring, which undergoes a Friedel-Crafts-type reaction.
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Previous asymmetric versions, all based on chiral ligands for Au(I), lack either scope or high enantiocontrol:
(a) Two examples only (44–99% yield, 92–93% ee):Chao, C.-M.; Vitale, M. R.; Toullec, P. Y.; Genêt, J.-P.; Michelet, V. Asymmetric Gold-Catalyzed Hydroarylation/Cyclization Reactions. Chem.─Eur. J. 2009, 15, 1319– 1323, DOI: 10.1002/chem.200802341
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27a
Asymmetric gold-catalyzed hydroarylation/cyclization reactions
Chao, Chung-Meng; Vitale, Maxime R.; Toullec, Patrick Y.; Genet, Jean-Pierre; Michelet, Veronique
Chemistry - A European Journal (2009), 15 (6), 1319-1323CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
An efficient Au1 catalytic system is described for the enantioselective hydroarylation/cyclization reaction of 1,6-enynes. Use of the (R)-4-MeO-3,5-(tBu)2-MeOBIPHEP-gold complex led to clean rearrangements implying the formal addn. of a carbon nucleophile (1,3,5-trimethoxybenzene, 1,3- dimethoxybenzene, pyrrole, 1,3,5-trimethoxy-2-bromobenzene and indole derivs.) to an alkene followed by a cyclization process.
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(b) One further example (86% yield, 16% ee):Pradal, A.; Chao, C.-M.; Vitale, M. R.; Toullec, P. Y.; Michelet, V. Asymmetric Au-Catalyzed Domino Cyclization/Nucleophile Addition Reactions of Enynes in the Presence of Water, Methanol and Electron-rich Aromatic Derivatives. Tetrahedron 2011, 67, 4371– 4377, DOI: 10.1016/j.tet.2011.03.071
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27b
Asymmetric Au-catalyzed domino cyclization/nucleophile addition reactions of enynes in the presence of water, methanol and electron-rich aromatic derivatives
Pradal, Alexandre; Chao, Chung-Meng; Vitale, Maxime R.; Toullec, Patrick Y.; Michelet, Veronique
Tetrahedron (2011), 67 (24), 4371-4377CODEN: TETRAB; ISSN:0040-4020. (Elsevier Ltd.)
An efficient Au(I) catalytic system is described for the asym. domino cyclization/functionalization reactions of functionalized 1,6-enynes in the presence of an external nucleophile. The use of (R)-4-MeO-3,5-(t-Bu)2-MeOBIPHEP ligand assocd. with gold led to clean rearrangements implying the formal addn. of an oxygen or carbon nucleophile to an alkene followed by a cyclization process. The enantiomeric excesses were highly dependent on the substrate/nucleophile combination. Very good enantiomeric excesses up to 98% were obtained in the case of substrates bearing larger groups (hindered diesters and disulfones) and in the case of hindered carbon nucleophiles.
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(c) Five examples (70–95% yield, 73–88% ee):Delpont, N.; Escofet, I.; Pérez-Galán, P.; Spiegl, D.; Raducan, M.; Bour, C.; Sinisi, R.; Echavarren, A. M. Modular Chiral Gold(I) Phosphite Complexes. Catal. Sci. Technol. 2013, 3, 3007– 3012, DOI: 10.1039/c3cy00250k
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27c
Modular chiral gold(I) phosphite complexes
Delpont, Nicolas; Escofet, Imma; Perez-Galan, Patricia; Spiegl, Dirk; Raducan, Mihai; Bour, Christophe; Sinisi, Riccardo; Echavarren, Antonio M.
Catalysis Science & Technology (2013), 3 (11), 3007-3012CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)
Chiral gold(I) phosphite complexes are readily prepd. modularly from 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol. These chiral gold(I) phosphite complexes are very reactive precatalysts for the [4+2] cycloaddn. of aryl-substituted 1,6-enynes with enantiomeric ratios ranging from 86:14 up to 94:6.
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(d) One example only (99% yield, 91% ee):Aillard, P.; Dova, D.; Magné, V.; Retailleau, P.; Cauteruccio, S.; Licandro, E.; Voituriez, A.; Marinetti, A. The Synthesis of Substituted Phosphathiahelicenes via Regioselective Bromination of a Preformed Helical Scaffold: A New Approach to Modular Ligands for Enantioselective Gold-Catalysis. Chem. Commun. 2016, 52, 10984– 10987, DOI: 10.1039/C6CC04765C
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27d
The synthesis of substituted phosphathiahelicenes via regioselective bromination of a preformed helical scaffold: a new approach to modular ligands for enantioselective gold-catalysis
Aillard, Paul; Dova, Davide; Magne, Valentin; Retailleau, Pascal; Cauteruccio, Silvia; Licandro, Emanuela; Voituriez, Arnaud; Marinetti, Angela
Chemical Communications (Cambridge, United Kingdom) (2016), 52 (73), 10984-10987CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
Substituted phosphathiahelicenes were prepd. via a straightforward two-step procedure involving the regioselective bromination of a preformed helical scaffold, followed by Pd-catalyzed coupling reactions with arylboronic acid or alkynes. The new helicenes were used as ligands in Au(I)-catalyzed [4+2] cyclizations of 1,6-enynes. The resulting dihydro-cyclopenta[b]naphthalene deriv. was obtained in excellent yields and with up to 91% ee.
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(e) 17 examples (61–99% yield, 58–92% ee):Zuccarello, G.; Mayans, J. G.; Escofet, I.; Scharnagel, D.; Kirillova, M. S.; Pérez-Jimeno, A. H.; Calleja, P.; Boothe, J. R.; Echavarren, A. M. Enantioselective Folding of Enynes by Gold(I) Catalysts with a Remote C₂-Chiral Element. J. Am. Chem. Soc. 2019, 141, 11858– 11863, DOI: 10.1021/jacs.9b06326
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27e
Enantioselective Folding of Enynes by Gold(I) Catalysts with a Remote C2-Chiral Element
Zuccarello, Giuseppe; Mayans, Joan G.; Escofet, Imma; Scharnagel, Dagmar; Kirillova, Mariia S.; Perez-Jimeno, Alba H.; Calleja, Pilar; Boothe, Jordan R.; Echavarren, Antonio M.
Journal of the American Chemical Society (2019), 141 (30), 11858-11863CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Chiral gold(I) catalysts have been designed based on a modified JohnPhos ligand with a distal C2-2,5-diarylpyrrolidine that creates a tight binding cavity. The C2-chiral element is close to where the C-C bond formation takes place in cyclizations of 1,6-enynes. These chiral mononuclear catalysts have been applied for the enantioselective 5-exo-dig and 6-endo-dig cyclization of different 1,6-enynes as well as in the first enantioselective total synthesis of three members of the carexane family of natural products. Opposite enantioselectivities have been achieved in seemingly analogous reactions of 1,6-enynes, which result from different chiral folding of the substrates based on attractive aryl-aryl interactions.
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(f) One example only (92% yield, 94% ee):Magné, V.; Sanogo, Y.; Demmer, C. S.; Retailleau, P.; Marinetti, A.; Guinchard, X.; Voituriez, A. Chiral Phosphathiahelicenes: Improved Synthetic Approach and Uses in Enantioselective Gold(I)-Catalyzed [2 + 2] Cycloadditions of N-Homoallenyl Tryptamines. ACS Catal. 2020, 10, 8141– 8148, DOI: 10.1021/acscatal.0c01819
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27f
Chiral Phosphathiahelicenes: Improved Synthetic Approach and Uses in Enantioselective Gold(I)-Catalyzed [2+2] Cycloadditions of N-Homoallenyl Tryptamines
Magne, Valentin; Sanogo, Youssouf; Demmer, Charles S.; Retailleau, Pascal; Marinetti, Angela; Guinchard, Xavier; Voituriez, Arnaud
ACS Catalysis (2020), 10 (15), 8141-8148CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
A chiral phosphathiahelicene scaffold displaying a phosphole and a thiophene unit as the terminal rings of the helical sequence I (7, M-isomer shown, Men = l-menthyl, R = H, X = O) has been synthesized and characterized by spectroscopic methods and X-ray diffraction studies. The phosphine oxides (HelPhos-V oxides) have been obtained following a robust and scalable synthetic approach, based on a nickel-promoted alkyne cyclotrimerization reaction. Then, late-stage functionalization has been carried out via a bromination/palladium coupling reaction sequence, giving phosphole P-oxides (9, 10; shown as I, X = O, R = Ph, C≡CPh). The HelPhos-V gold(I) complexes (11, shown as I, R = H, X = AuCl) have been used as catalysts in the unprecedented enantioselective [2+2] cyclization of N-homoallenyl tryptamine derivs., to afford indolenine-fused cyclobutanes II [Ns = 4-NO2C6H4SO2, R = Me, RR = (CH2)5; R1 = H, Me, Cl, MeO] in good isolated yields, with enantiomeric excesses up to 93%.
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N-Triflyl phosphoric amide D1 has a pK_a value 0.9 units lower than the corresponding phosphoric acid TRIP-H (4.2 vs 3.3, both values in DMSO at 25 °C):
Christ, P.; Lindsay, A. G.; Vormittag, S. S.; Neudörfl, J.-M.; Berkessel, A.; O’Donoghue, A. C. pK_a Values of Chiral Brønsted Acid Catalysts: Phosphoric Acids/Amides, Sulfonyl/Sulfuryl Imides, and Perfluorinated TADDOLs (TEFDDOLs). Chem.─Eur. J. 2011, 17, 8524– 8528, DOI: 10.1002/chem.201101157
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pKa Values of Chiral Bronsted Acid Catalysts: Phosphoric Acids/Amides, Sulfonyl/Sulfuryl Imides, and Perfluorinated TADDOLs (TEFDDOLs)
Christ, Philipp; Lindsay, Anita G.; Vormittag, Sonja S.; Neudoerfl, Joerg-M.; Berkessel, Albrecht; O'Donoghue, AnnMarie C.
Chemistry - A European Journal (2011), 17 (31), 8524-8528, S8524/1-S8524/58CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
Quant. conversion of the Bronsted acid to the corresponding conjugate base in the presence of NaOH was recoreded using UV/Vis spectra with a const. concn. of indicator, 4-chloro-2,6-dinitrophenol (prepd.), 2,4-dinitrophenol, 2,4-dinitronaphthol, 4-nitrophenol, or phenol, in DMSO. Phosphoric acids stability was detd. via 1H NMR under conditions for pKa detn.
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Raubenheimer, H. G.; Schmidbaur, H. Gold Chemistry Guided by the Isolobality Concept. Organometallics 2012, 31, 2507– 2522, DOI: 10.1021/om2010113
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Gold chemistry guided by the isolobality concept
Raubenheimer, Helgard G.; Schmidbaur, Hubert
Organometallics (2012), 31 (7), 2507-2522CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
A review. Chem. of gold polynuclear compds. is considered from the point of view of isolobality concept. The general isolobality concept presented by Hoffmann, Stone, and Mingos in the early 1980s has had-tacitly or explicitly-a great impact on the development of many areas of inorg., organometallic, and coordination chem. Pertinent considerations were fruitful esp. in gold chem., because isolobal relations between gold(I) cations [Au]+ and their complexes [LAu]+ on the one hand and protons [H]+, various carbocations [R]+, and other simple species on the other are particularly obvious. Work guided by these relationships has included almost all fields of gold chem., from simple high-energy species in the gas phase to homoat. clusters of gold atoms or heteroat. aggregates with main-group and transition elements. Recent work has also concd. on the specific mechanisms of reactions catalyzed either by protons or by the above gold cations with a variety of new ligands L in sep. or tandem reaction sequences. The present review summarizes classical and current lines of research that have followed the original concept up to its present frontier version of "autogenic isolobality".
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Reid, J. P.; Goodman, J. M. Goldilocks Catalysts: Computational Insights into the Role of the 3,3′ Substituents on the Selectivity of BINOL-Derived Phosphoric Acid Catalysts. J. Am. Chem. Soc. 2016, 138, 7910– 7917, DOI: 10.1021/jacs.6b02825
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Goldilocks Catalysts: Computational Insights into the Role of the 3,3' Substituents on the Selectivity of BINOL-Derived Phosphoric Acid Catalysts
Reid, Jolene P.; Goodman, Jonathan M.
Journal of the American Chemical Society (2016), 138 (25), 7910-7917CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
BINOL-derived phosphoric acids provide effective asym. catalysis for many org. reactions. Catalysts based on this scaffold show a large structural diversity, esp. in the 3,3' substituents, and little is known about the mol. requirements for high selectivity. As a result, selection of the best catalyst for a particular transformation requires a trial and error screening process, as the size of the 3,3' substituents is not simply related to their efficacy: the right choice is neither too large nor too small. We have developed an approach to identify and quantify structural features on the catalyst that det. selectivity. We show that the application of quant. steric parameters (a new measure, AREA(θ), and rotation barrier) to an imine hydrogenation reaction allows the identification of catalyst features necessary for efficient stereoinduction, validated by QM/MM hybrid calcns.
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(a) Kepp, K. P. A Quantitative Scale of Oxophilicity and Thiophilicity. Inorg. Chem. 2016, 55, 9461– 9470, DOI: 10.1021/acs.inorgchem.6b01702
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31a
A Quantitative Scale of Oxophilicity and Thiophilicity
Kepp, Kasper P.
Inorganic Chemistry (2016), 55 (18), 9461-9470CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
Oxophilicity and thiophilicity are widely used concepts with no quant. definition. In this paper, a simple, generic scale is developed that solves issues with ref. states and system dependencies and captures empirically known tendencies toward oxygen. This enables a detailed anal. of the fundamental causes of oxophilicity. Notably, the notion that oxophilicity relates to Lewis acid hardness is invalid. Rather, oxophilicity correlates only modestly and inversely with abs. hardness and more strongly with electronegativity and effective nuclear charge. Since oxygen is highly electroneg., ionic bonding is stronger to metals of low electronegativity. Left-side d-block elements with low effective nuclear charges and electronegativities are thus highly oxophilic, and the f-block elements, not because of their hardness, which is normal, but as a result of the small ionization energies of their outermost valence electrons, can easily transfer electrons to fulfill the electron demands of oxygen. Consistent with empirical experience, the most oxophilic elements are found in the left part of the d block, the lanthanides, and the actinides. The d-block elements differ substantially in oxophilicity, quantifying their different uses in a wide range of chem. reactions; thus, the use of mixed oxo- and thiophilic (i.e., "mesophilic") surfaces and catalysts as a design principle can explain the success of many recent applications. The proposed scale may therefore help to rationalize and improve chem. reactions more effectively than current qual. considerations of oxophilicity.
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(b) Izaga, A.; Herrera, R. P.; Gimeno, M. C. Gold(I)-Mediated Thiourea Organocatalyst Activation: A Synergic Effect for Asymmetric Catalysis. ChemCatChem 2017, 9, 1313– 1321, DOI: 10.1002/cctc.201601527
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31b
Gold(I)-Mediated Thiourea Organocatalyst Activation: A Synergic Effect for Asymmetric Catalysis
Izaga, Anabel; Herrera, Raquel P.; Gimeno, M. Concepcion
ChemCatChem (2017), 9 (7), 1313-1321CODEN: CHEMK3; ISSN:1867-3880. (Wiley-VCH Verlag GmbH & Co. KGaA)
Several group 11 metal complexes with chiral thiourea organocatalysts have been prepd. and tested as organocatalysts. The promising results on the influence of metal-assisted thiourea organocatalysts in the asym. Friedel-Crafts alkylation of indole with nitrostyrene are described. Better results with the metal complexes have been achieved because of the cooperative effects between the chiral thiourea and the metal. The synergic effect between both species is higher than the effect promoted by each one sep., esp. for gold(I). These outcomes are attributed to a pioneering gold(I) activation of the thiourea catalysts, affording a more acidic and rigid catalytic complex than that provided by the thiourea alone. Furthermore, the use of the gold-thiourea organocatalyst allows reducing the catalyst loading to 1-3 mol %. This contribution could become an important starting point for further investigations opening a new line of research overlooked so far in the literature.
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Reichardt, C. Solvatochromic Dyes as Solvent Polarity Indicators. Chem. Rev. 1994, 94, 2319– 2358, DOI: 10.1021/cr00032a005
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Solvatochromic Dyes as Solvent Polarity Indicators
Reichardt, Christian
Chemical Reviews (Washington, DC, United States) (1994), 94 (8), 2319-58CODEN: CHREAY; ISSN:0009-2665.
This review with 345 refs. compiles pos. and neg. solvatochromic compds. which have been used to establish empirical scales of solvent polarity by means of UV/visible/near-IR spectroscopic measurements in soln. with particular emphasis on the ET(30) scale derived from neg. solvatochromic pyridinium N-phenolate betaine dyes. A discussion is presented on the concept of solvent polarity and how empirical parameters of solvent polarity can be derived and understood in the framework of linear free-energy relationships.
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All gold complexes used so far for the enantioselective cyclization of O-tethered 1,6-enynes bear chiral ligands. For a complete overview, see the following:
(a) Mato, M.; Franchino, A.; García-Morales, C.; Echavarren, A. M. Gold-Catalyzed Synthesis of Small Rings. Chem. Rev. 2021, 121, 8613– 8684, DOI: 10.1021/acs.chemrev.0c00697
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33a
Gold-Catalyzed Synthesis of Small Rings
Mato, Mauro; Franchino, Allegra; Garcia-Morales, Cristina; Echavarren, Antonio M.
Chemical Reviews (Washington, DC, United States) (2021), 121 (14), 8613-8684CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
A review. This review aimed to provide a comprehensive summary of all the major advances and discoveries made in the gold-catalyzed synthesis of cyclopropanes, cyclopropenes, cyclobutanes, cyclobutenes, and their corresponding heterocyclic or heterosubstituted analogs.
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For seminal examples, see the following:
(b) Chao, C.-M.; Beltrami, D.; Toullec, P. Y.; Michelet, V. Asymmetric Au(I)-Catalyzed Synthesis of Bicyclo[4.1.0]heptene Derivatives via a Cycloisomerization Process of 1,6-Enynes. Chem. Commun. 2009, 6988– 6990, DOI: 10.1039/b913554e
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Asymmetric Au(I)-catalyzed synthesis of bicyclo[4.1.0]heptene derivatives via a cycloisomerization process of 1,6-enynes
Chao, Chung-Meng; Beltrami, Denis; Toullec, Patrick Y.; Michelet, Veronique
Chemical Communications (Cambridge, United Kingdom) (2009), (45), 6988-6990CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
The enantioselective asym. gold-catalyzed cycloisomerization reactions of heteroatom tethered 1,6-enynes are conducted in the presence of a chiral cationic Au(I) catalyst (I/AgOTf) in toluene under mild conditions. These transformations lead to functionalized aza- or oxabicyclo[4.1.0]heptene derivs., e.g., II, in excellent enantiomeric excesses ranging from 90-98%.
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(c) Teller, H.; Corbet, M.; Mantilli, L.; Gopakumar, G.; Goddard, R.; Thiel, W.; Fürstner, A. One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone. J. Am. Chem. Soc. 2012, 134, 15331– 15342, DOI: 10.1021/ja303641p
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One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone
Teller, Henrik; Corbet, Matthieu; Mantilli, Luca; Gopakumar, Gopinadhanpillai; Goddard, Richard; Thiel, Walter; Fuerstner, Alois
Journal of the American Chemical Society (2012), 134 (37), 15331-15342CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Nonracemic gold complexes such as I (R = Ph, 4-Me3CC6H4) contg. monoligated phosphoramidites incorporating TADDOL-related diols with an acyclic backbone were enantioselective catalysts for a variety of transformations with good to outstanding enantioselectivities; the novel ligands incorporate an acyclic di-Me ether backbone instead of the (isopropylidene) acetal moiety characteristic for traditional TADDOL ligands. Gold TADDOL-related monocyclic phosphoramidite complexes were used as catalysts for diastereoselective and enantioselective reactions including the [2+2] and [4+2] cycloaddns. of eneallenes such as II [R1 = Ph, 4-MeOC6H4, 4-Me3COC6H4; X = (MeO2C)2C, (PhCH2O2C)2C, (Me3CO2C)2C, TsN, (PhSO2)2C] and dieneallenes to bicyclic bicycloheptanes such as III [R1 = Ph, 4-MeOC6H4, 4-Me3COC6H4; X = (MeO2C)2C, (PhCH2O2C)2C, (Me3CO2C)2C, TsN, (PhSO2)2C] and alkylidenehydrindanes, the cycloisomerizations of protected propargyl allyl amines and of allylic propargyl ethers to tetrahydrocyclopropapyridines and dihydrocyclopropapyrans, the hydroarylation of (allenylmethyl)arylcarbamates to give alkenylindolines, and the hydroamination and hydroalkoxylation reactions of pentadienylsulfonamides and a pentadienol to give alkenylpyrrolidines and an alkenyltetrahydrofuran. The practical use of gold TADDOL-related monocyclic phosphoramidite complexes is shown by an efficient synthesis of the antidepressive drug candidate (-)-GSK 1360707 IV•HCl using a gold complex-catalyzed cycloisomerization reaction as the key step. The structures of transition states and intermediates for the cycloisomerization of an (allyl)(bromophenylpropargyl)methanesulfonamide to enantiomeric tetrahydrocyclopropapyridines were detd. using d. functional theor. calcns. The structures of I (R = Ph, 4-Me3CC6H4), ent-I (R = 2-naphthyl), II (R1 = Ph; X = TsN), a tetrahydrocyclopropapyridine, a dioxatricycloundecene, a dihydropyranooxepine, and a dioxatetracycloundecane were detd. by X-ray crystallog.
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Sanjuán, A. M.; Martínez, A.; García-García, P.; Fernández-Rodríguez, M. A.; Sanz, R. Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes. Beilstein J. Org. Chem. 2013, 9, 2242– 2249, DOI: 10.3762/bjoc.9.263
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Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes
Sanjuan, Ana M.; Martinez, Alberto; Garcia-Garcia, Patricia; Fernandez-Rodriguez, Manuel A.; Sanz, Roberto
Beilstein Journal of Organic Chemistry (2013), 9 (), 2242-2249, 8 pp.CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
The cyclization of o-(alkynyl)-3-(methylbut-2-enyl)benzenes, 1,6-enynes having a condensed arom. ring at C3-C4 positions, has been studied under the catalysis of cationic gold(I) complexes. The selective 6-endo-dig mode of cyclization obsd. for the 7-substituted substrates in the presence of water or methanol giving rise to hydroxy(methoxy)-functionalized dihydronaphthalene derivs. is highly remarkable in the context of the obsd. reaction pathways for the cycloisomerizations of 1,6-enynes bearing a trisubstituted olefin.
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See Supporting Information for discussion on other nucleophiles and reaction side products.
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(a) Pfeifer, L.; Engle, K. M.; Pidgeon, G. W.; Sparkes, H. A.; Thompson, A. L.; Brown, J. M.; Gouverneur, V. Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power. J. Am. Chem. Soc. 2016, 138, 13314– 13325, DOI: 10.1021/jacs.6b07501
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36a
Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power
Pfeifer, Lukas; Engle, Keary M.; Pidgeon, George W.; Sparkes, Hazel A.; Thompson, Amber L.; Brown, John M.; Gouverneur, Veronique
Journal of the American Chemical Society (2016), 138 (40), 13314-13325CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5'-fluoro-5'-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F-. Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramol. chem. Herein we disclose a detailed study examg. the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in soln. phase and explore the reactivity of these complexes as a fluoride source in SN2 chem. Exptl. data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett anal. of aryl groups on the urea indicates that fluoride binding is dependent on σp and σm parameters with stronger binding being obsd. for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alc.-fluoride complexes, but SN2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate consts. at higher diln. support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF]- (U = urea) resulting from partial dissocn. of the parent compd. [U2F]-. The dissocn. processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in soln.
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(b) Ibba, F.; Pupo, G.; Thompson, A. L.; Brown, J. M.; Claridge, T. D. W.; Gouverneur, V. Impact of Multiple Hydrogen Bonds with Fluoride on Catalysis: Insight from NMR Spectroscopy. J. Am. Chem. Soc. 2020, 142, 19731– 19744, DOI: 10.1021/jacs.0c09832
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36b
Impact of Multiple Hydrogen Bonds with Fluoride on Catalysis: Insight from NMR Spectroscopy
Ibba, Francesco; Pupo, Gabriele; Thompson, Amber L.; Brown, John M.; Claridge, Timothy D. W.; Gouverneur, Veronique
Journal of the American Chemical Society (2020), 142 (46), 19731-19744CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Hydrogen-bonding interactions have been explored in catalysis, enabling complex chem. reactions. Recently, enantioselective nucleophilic fluorination with metal alkali fluoride has been accomplished with BINAM-derived bisurea catalysts, presenting up to four NH hydrogen-bond donors (HBDs) for fluoride. These catalysts bring insol. CsF and KF into soln., control fluoride nucleophilicity, and provide a chiral microenvironment for enantioselective fluoride delivery to the electrophile. These attributes encouraged a 1H/19F NMR study to gain information on hydrogen-bonding networks with fluoride in soln., as well as how these arrangements impact the efficiency of catalytic nucleophilic fluorination. Herein, NMR expts. enabled the detn. of the no. and magnitude of HB contacts to fluoride for thirteen bisurea catalysts. These data supplemented by diagnostic coupling consts. 1hJNH···F- give insight into how multiple H bonds to fluoride influence reaction performance. In dichloromethane (DCM-d2), nonalkylated BINAM-derived bisurea catalyst engages two of its four NH groups in hydrogen bonding with fluoride, an arrangement that allows effective phase-transfer capability but low control over enantioselectivity for fluoride delivery. The more efficient N-alkylated BINAM-derived bisurea catalysts undergo urea isomerization upon fluoride binding and form dynamically rigid trifurcated hydrogen-bonded fluoride complexes that are structurally similar to their conformation in the solid state. Insight into how the countercation influences fluoride complexation is provided based on NMR data characterizing the species formed in DCM-d2 when reacting a bisurea catalyst with tetra-n-butylammonium fluoride (TBAF) or CsF. Structure-activity anal. reveals that the three hydrogen-bond contacts with fluoride are not equal in terms of their contribution to catalyst efficacy, suggesting that tuning individual electronic environment is a viable approach to control phase-transfer ability and enantioselectivity.
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D’Abrosca, B.; Fiorentino, A.; Golino, A.; Monaco, P.; Oriano, P.; Pacifico, S. Carexanes: Prenyl Stilbenoid Derivatives from Carex distachya. Tetrahedron Lett. 2005, 46, 5269– 5272, DOI: 10.1016/j.tetlet.2005.06.036
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Carexanes: prenyl stilbenoid derivatives from Carex distachya
D'Abrosca, Brigida; Fiorentino, Antonio; Golino, Annunziata; Monaco, Pietro; Oriano, Palma; Pacifico, Severina
Tetrahedron Letters (2005), 46 (32), 5269-5272CODEN: TELEAY; ISSN:0040-4039. (Elsevier B.V.)
Metabolites with a new mol. skeleton, named carexane, have been isolated from the leaves of Carex distachya. The structures have been detd. on the basis of the spectroscopic characteristics of the compds. Bidimensional NMR has furnished important data useful for the characterization and the stereochem. of the mols. The compds. have a tetracyclic skeleton derived from the coupling of the prenyl moiety on a stilbenoid structure.
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Martín-Torres, I.; Ogalla, G.; Yang, J.-M.; Rinaldi, A.; Echavarren, A. M. Enantioselective Alkoxycyclization of 1,6-Enynes with Gold(I)-Cavitands: Total Synthesis of Mafaicheenamine C. Angew. Chem., Int. Ed. 2021, 60, 9339– 9344, DOI: 10.1002/anie.202017035
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Enantioselective Alkoxycyclization of 1,6-Enynes with Gold(I)-Cavitands: Total Synthesis of Mafaicheenamine C
Martin-Torres, Inmaculada; Ogalla, Gala; Yang, Jin-Ming; Rinaldi, Antonia; Echavarren, Antonio M.
Angewandte Chemie, International Edition (2021), 60 (17), 9339-9344CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
Chiral gold(I)-cavitand complexes have been developed for the enantioselective alkoxycyclization of 1,6-enynes. This enantioselective cyclization has been applied for the first total synthesis of carbazole alkaloid (+)-mafaicheenamine C (I) and its enantiomer, establishing its configuration as R. The cavity effect was also evaluated in the cycloisomerization of dienynes. A combination of expts. and theor. studies demonstrates that the cavity of the gold(I) complexes forces the enynes to adopt constrained conformations, which results in the high obsd. regio- and stereoselectivities.
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Witham, C. A.; Mauleón, P.; Shapiro, N. D.; Sherry, B. D.; Toste, F. D. Gold(I)-Catalyzed Oxidative Rearrangements. J. Am. Chem. Soc. 2007, 129, 5838– 5839, DOI: 10.1021/ja071231+
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Gold(I)-catalyzed oxidative rearrangements
Witham, Cole A.; Mauleon, Pablo; Shapiro, Nathan D.; Sherry, Benjamin D.; Toste, F. Dean
Journal of the American Chemical Society (2007), 129 (18), 5838-5839CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
A series of gold(I)-catalyzed oxidative rearrangement reactions of alkynes using sulfoxides as stoichiometric oxidants are reported. The reactions were postulated to proceed through intermol. oxygen atom transfer from the sulfoxide to gold(I)-carbenoid intermediates. Under the conditions for gold(I)-catalyzed oxidative rearrangement, 1,6-enynes were isomerized to cyclopropyl aldehydes, homopropargyl azides produced pyrrolones, acetylenic α-diazoketones formed cyclic en-1,4-diones, and propargyl esters produced 2-acyloxyenals.
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Wang, W.; Yang, J.; Wang, F.; Shi, M. Axially Chiral N-Heterocyclic Carbene Gold(I) Complex Catalyzed Asymmetric Cycloisomerization of 1,6-Enynes. Organometallics 2011, 30, 3859– 3869, DOI: 10.1021/om2004404
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Axially chiral n-heterocyclic carbene gold(I) complex catalyzed asymmetric cycloisomerization of 1,6-enynes
Wang, Wenfeng; Yang, Jinming; Wang, Feijun; Shi, Min
Organometallics (2011), 30 (14), 3859-3869CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
A new class of axially chiral NHC-Au(I) complexes I [2-11; R1 = Me, PhCH2; R2 = H, R3 = PhCH2, Ac, PhCO, Boc, N-Boc-L-prolyl, N-Boc-D-prolyl; R2-R3 = (CH2)4, :CH-2-HOC6H4, :CHPh; R2, R3 = Me, PhCH2] and 2,2'-bis-benzimidazolylidene complex (1) were developed from optically active BINAM and fully characterized by NMR, ESI-MS, and IR spectroscopic data, and x-ray structures for three of the complexes. Gold(I) center exhibits a nearly linear coordination geometry. Within the carried out investigations herein, the sterically less hindered gold(I) complex, having a 1-pyrrolidinyl group in the 2'-position, was shown to be the best catalyst in asym. acetoxycyclization of 1,6-azaenyne HC≡CCH2NTsCH2CH:CHPh (52a), giving product 3-(acetoxyphenylmethyl)4-methylene-1-tosylpyrrolidine (53a) in >99% yield with 59% ee at 0°, and the sterically less hindered gold(I) catalyst (aS)-2a (shown as I, R1 = Me, R2 = H, R3 = Ac) is the best catalyst in the asym. oxidative rearrangement of 1,6-enynes, affording the corresponding aldehydes, 6-R-3-(arylsulfonyl)-3-azabicyclo[3.1.0]hexane-1-carboxaldehydes (56a,c-g; R = Ph, mesityl, CH2tBu; aryl = p-tolyl, 4-BrC6H4, 4-NO2C6H4, 2,4,6-iPr3C6H2) and 6-phenyl-3-oxabicyclo[3.1.0]hexane-1-carboxaldehyde (56h) in excellent yields (up to >99%) and modest enantioselectivities (3.1-70% ee) using PhCl as the solvent at 10°.
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(a) Yao, T.; Zhang, X.; Larock, R. C. AuCl₃-Catalyzed Synthesis of Highly Substituted Furans from 2-(1-Alkynyl)-2-alken-1-ones. J. Am. Chem. Soc. 2004, 126, 11164– 11165, DOI: 10.1021/ja0466964
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41a
AuCl3-Catalyzed synthesis of highly substituted furans from 2-(1-alkynyl)-2-alken-1-ones
Yao, Tuanli; Zhang, Xiaoxia; Larock, Richard C.
Journal of the American Chemical Society (2004), 126 (36), 11164-11165CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
Highly substituted furans, e.g., I, have been synthesized by the reaction of 2-(1-alkynyl)-2-alken-1-ones and various nucleophiles under very mild reaction conditions in good to excellent yields. Gold and some other transition metals were efficient catalysts for this reaction.
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(b) Rauniyar, V.; Wang, Z. J.; Burks, H. E.; Toste, F. D. Enantioselective Synthesis of Highly Substituted Furans by a Copper(II)-Catalyzed Cycloisomerization-Indole Addition Reaction. J. Am. Chem. Soc. 2011, 133, 8486– 8489, DOI: 10.1021/ja202959n
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41b
Enantioselective Synthesis of Highly Substituted Furans by a Copper(II)-Catalyzed Cycloisomerization-Indole Addition Reaction
Rauniyar, Vivek; Wang, Z. Jane; Burks, Heather E.; Toste, F. Dean
Journal of the American Chemical Society (2011), 133 (22), 8486-8489CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
A catalytic enantioselective reaction based on a copper(II) catalyst strictly contg. chiral anionic ligands is described. In the present work, copper(II)-phosphate catalyst promotes the intramol. heterocyclization of 2-(1-alkynyl)-2-alkene-1-ones and facilitates high levels of enantioselectivity in the subsequent nucleophile attack resulting in highly substituted furans, e.g., I. Mechanistic studies suggest that formation of a copper(II)-indole species is important for catalysis.
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(c) Force, G.; Ki, Y. L. T.; Isaac, K.; Retailleau, P.; Marinetti, A.; Betzer, J.-F. Paracyclophane-based Silver Phosphates as Catalysts for Enantioselective Cycloisomerization/Addition Reactions: Synthesis of Bicyclic Furans. Adv. Synth. Catal. 2018, 360, 3356– 3366, DOI: 10.1002/adsc.201800587
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41c
Paracyclophane-based Silver Phosphates as Catalysts for Enantioselective Cycloisomerization/Addition Reactions: Synthesis of Bicyclic Furans
Force, Guillaume; Ki, Yvette Lock Toy; Isaac, Kevin; Retailleau, Pascal; Marinetti, Angela; Betzer, Jean-Francois
Advanced Synthesis & Catalysis (2018), 360 (17), 3356-3366CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
This manuscript discloses the first use of chiral phosphates based on C2-sym. paracyclophane scaffolds as chiral counterions in transition metal catalysis, showing that they may compare favorably with other known chiral phosphates, such as the TRIP phosphate. The targeted catalytic reaction is a silver(I) promoted domino heterocyclization of 2-(1-alkynyl)-2-alken-1-one derivs., in the presence of C-, or N-nucleophiles, which provides an efficient access to substituted bicyclic furans. Results show that high levels of enantioselectivity can be attained with either paracyclophane-based phosphates or TRIP phosphates, when the nucleophilic reactants display N-H functions in appropriate positions, near to the nucleophilic center. Therefore, the involvement of H-bonding between the NH function and the phosphate in the enantio-detg. step is postulated.
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³¹P{¹H} and ¹⁹F{¹H} NMR spectra remained unchanged, confirming that the chloride was not scavenged. See Supporting Information for details.
There is no corresponding record for this reference.
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(a) Burés, J. A Simple Graphical Method to Determine the Order in Catalyst. Angew. Chem., Int. Ed. 2016, 55, 2028– 2031, DOI: 10.1002/anie.201508983
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43a
A Simple Graphical Method to Determine the Order of a Reaction in Catalyst
Bures, Jordi
Angewandte Chemie, International Edition (2016), 55 (6), 2028-2031CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A graphical anal. to elucidate the order in catalyst is presented. This anal. uses a normalized time scale, t [cat]Tn, to adjust entire reaction profiles constructed with concn. data. The method is fast and simple to perform because it directly uses the concn. data, therefore avoiding the data handling that is usually required to ext. rates. Compared to methods that use rates, the normalized time scale anal. requires fewer expts. and minimizes the effects of exptl. errors by using information on the entire reaction profile.
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(b) Burés, J. Variable Time Normalization Analysis: General Graphical Elucidation of Reaction Orders from Concentration Profiles. Angew. Chem., Int. Ed. 2016, 55, 16084– 16087, DOI: 10.1002/anie.201609757
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43b
Variable Time Normalization Analysis: General Graphical Elucidation of Reaction Orders from Concentration Profiles
Bures, Jordi
Angewandte Chemie, International Edition (2016), 55 (52), 16084-16087CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
The recent technol. evolution of reaction monitoring techniques has not been paralleled by the development of modern kinetic analyses. The analyses currently used disregard part of the data acquired, thus requiring an increased no. of expts. to obtain sufficient kinetic information for a given chem. reaction. Herein, we present a simple graphical anal. method that takes advantage of the data-rich results provided by modern reaction monitoring tools. This anal. uses a variable normalization of the time scale to enable the visual comparison of entire concn. reaction profiles. As a result, the order in each component of the reaction, as well as kobs , is detd. with just a few expts. using a simple and quick math. data treatment. This anal. facilitates the rapid extn. of relevant kinetic information and will be a valuable tool for the study of reaction mechanisms.
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(c) Nielsen, C. D.-T.; Burés, J. Visual Kinetic Analysis. Chem. Sci. 2019, 10, 348– 353, DOI: 10.1039/C8SC04698K
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43c
Visual kinetic analysis
Nielsen, Christian D.-T.; Bures, Jordi
Chemical Science (2019), 10 (2), 348-353CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
Visual kinetic analyses ext. meaningful mechanistic information from exptl. data using the naked-eye comparison of appropriately modified progress reaction profiles. Basic kinetic information is obtained easily and quickly from just a few expts. Therefore, these methods are valuable tools for all chemists working in process chem., synthesis or catalysis with an interest in mechanistic studies. This minireview describes the visual kinetic analyses developed in the last fifteen years and provides answers to the most common queries of new users. Furthermore, a video tutorial is attached detailing the implementation of both VTNA and RPKA.
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Briggs, G. E.; Haldane, J. B. S. A Note on the Kinetics of Enzyme Action. Biochem. J. 1925, 19, 338– 339, DOI: 10.1042/bj0190338
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Note on the kinetics of enzyme action
Briggs, G. E.; Haldane, J. B. S.
Biochemical Journal (1925), 19 (), 338-9CODEN: BIJOAK; ISSN:0264-6021.
A criticism of Michaelis and Menton's equation (C. A. 7, 2232) for enzyme action.
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Application of this model rests on a series of underlying assumptions, all satisfied in the present case (see Supporting Information).
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(a) Michaelis, L.; Menten, M. L. Die Kinetik der Invertinwirkung. Biochem. Z. 1913, 49, 333– 369
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45a
Kinetics of Invertase Action
Michaelis, L.; Menten, Maud L.
Biochemische Zeitschrift (1913), 49 (), 333-69CODEN: BIZEA2; ISSN:0366-0753.
The course of sugar inversion by invertase is consistent with the assumption that saccharose and enzyme unite to form a combination, of which the dissociation const. is 0.0167. The comp. is labile and breaks up into 1 mol. each of glucose, fructose, and invertin. Invertin has an affinity for glucose and fructose, as well as for other carbohydrates and higher alcs. (mannitol and glycerol), although in none of these cases is the affinity so great as for saccharose. The compds. formed with these substs. are not labile and the substs. do not suffer decomp. They show their combining capacity for the enzyme by the fact that their presence retards the inversion of saccharose by invertin. The concs. of all the invertin-carbohydrate compds. were calc. according to the law of mass action and the dissociation consts. detd. The decomp. of the saccharose-invertin compd. being a monomol. reaction, the inversion velocity at any time is directly proportional to the conc. of the compd. From the above assumptions a differential equation is derived which agrees well with the observed inversion rates of saccharose.
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(b) Johnson, K. A.; Goody, R. S. The Original Michaelis Constant: Translation of the 1913 Michaelis−Menten Paper. Biochemistry 2011, 50, 8264– 8269, DOI: 10.1021/bi201284u
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45b
The Original Michaelis Constant: Translation of the 1913 Michaelis-Menten Paper
Johnson, Kenneth A.; Goody, Roger S.
Biochemistry (2011), 50 (39), 8264-8269CODEN: BICHAW; ISSN:0006-2960. (American Chemical Society)
Nearly 100 years ago Michaelis and Menten published their now classic paper in which they showed that the rate of an enzyme-catalyzed reaction is proportional to the concn. of the enzyme-substrate complex predicted by the Michaelis-Menten equation. Because the original text was written in German yet is often quoted by English-speaking authors, we undertook a complete translation of the 1913 publication, which we provide as Supporting Information. Here we introduce the translation, describe the historical context of the work, and show a new anal. of the original data. In doing so, we uncovered several surprises that reveal an interesting glimpse into the early history of enzymol. In particular, our reanal. of Michaelis and Menten's data using modern computational methods revealed an unanticipated rigor and precision in the original publication and uncovered a sophisticated, comprehensive anal. that has been overlooked in the century since their work was published. Michaelis and Menten not only analyzed initial velocity measurements but also fit their full time course data to the integrated form of the rate equations, including product inhibition, and derived a single global const. to represent all of their data. That const. was not the Michaelis const., but rather Vmax/Km, the specificity const. times the enzyme concn. (kcat/Km × E0).
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Blackmond, D. G. Reaction Progress Kinetic Analysis: A Powerful Methodology for Mechanistic Studies of Complex Catalytic Reactions. Angew. Chem., Int. Ed. 2005, 44, 4302– 4320, DOI: 10.1002/anie.200462544
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Reaction progress kinetic analysis: A powerful methodology for mechanistic studies of complex catalytic reactions
Blackmond, Donna G.
Angewandte Chemie, International Edition (2005), 44 (28), 4302-4320CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Reaction progress kinetic anal. to obtain a comprehensive picture of complex catalytic reaction behavior is described. This methodol. employs in situ measurements and simple manipulations to construct a series of graphical rate equations that enable anal. of the reaction to be accomplished from a minimal no. of expts. Such an anal. helps to describe the driving forces of a reaction and may be used to help distinguish between different proposed mechanistic models. This Review describes the procedure for undertaking such anal. for any new reaction under study.
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Correction:Blackmond, D. G. Angew. Chem., Int. Ed. 2006, 45, 2162– 2162, DOI: 10.1002/anie.200690050
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Reaction progress kinetic analysis: A powerful methodology for mechanistic studies of complex catalytic reactions. [Erratum to document cited in CA143:132869]
Blackmond, Donna G.
Angewandte Chemie, International Edition (2006), 45 (14), 2162CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
A review. Ref. [29] should read as follows: T. Schultz, PhD Thesis, Universitat Basel (Switzerland), 2004.
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Franchino, A.; Montesinos-Magraner, M.; Echavarren, A. M. Silver-Free Catalysis with Gold(I) Chloride Complexes. Bull. Chem. Soc. Jpn. 2021, 94, 1099– 1117, DOI: 10.1246/bcsj.20200358
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47
Silver-Free Catalysis with Gold(I) Chloride Complexes
Franchino, Allegra; Montesinos-Magraner, Marc; Echavarren, Antonio M.
Bulletin of the Chemical Society of Japan (2021), 94 (3), 1099-1117CODEN: BCSJA8; ISSN:0009-2673. (Chemical Society of Japan)
A review. Gold(I) chloride complexes are stable, widespread precatalysts that generally require activation by halide abstraction to display useful catalytic activity. Chloride scavenging is typically performed in situ by using silver salts. This procedure, apart from mandating the use of an addnl. metal, often neg. impacts the reaction outcome, because Ag additives are not catalytically innocent (silver effect). Therefore, both the development of alternative chloride scavengers and the design of self-activating gold(I) chloride complexes endowed with special ligands have lately been the subject of intense research efforts. This describes recent advances in the field of silver-free Au(I) catalysis employing gold(I) chloride complexes, with an emphasis on approaches emerged in the last decade.
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Lineweaver, H.; Burk, D. The Determination of Enzyme Dissociation Constants. J. Am. Chem. Soc. 1934, 56, 658– 666, DOI: 10.1021/ja01318a036
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48
Determination of enzyme dissociation constants
Lineweaver, Hans; Burk, Dean
Journal of the American Chemical Society (1934), 56 (), 658-66CODEN: JACSAT; ISSN:0002-7863.
Graphical methods involving const. slopes and straight-line extrapolations have been developed for testing and interpreting kinetic data and for detg. dissocn. consts. of enzyme-substrate and enzyme-inhibitor compds. and other related consts. when the data are found to be consistent with an assigned mechanism. Representative analyses are given for invertase, raffinase, amylase, citric dehydrogenase, catalase, oxygenase, esterase and lipase, involving substrate activation, substrate inhibition, general competitive and noncompetitive inhibition, steady states and reactions of various orders. The various methods described are applicable to gen. chem. catalysis, homogeneous or heterogeneous.
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The uncertainty refers not to experimental variation but only to the mathematical error of the linear regression, as determined by Excel LINEST routine. If all data from time 0 to 10 h are used in the Lineawer–Burk plot, a K_M value of 63 ± 4 is obtained, leading to identical conclusions regarding the partial order in substrate (see Supporting Information).
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Burés, J. What is the Order of a Reaction?. Top. Catal. 2017, 60, 631– 633, DOI: 10.1007/s11244-017-0735-y
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50
What is the Order of a Reaction?
Bures, Jordi
Topics in Catalysis (2017), 60 (8), 631-633CODEN: TOCAFI; ISSN:1022-5528. (Springer)
The order of a reaction in some species seems an obvious, trivial concept that all chemists master. However, in complex situations such as catalytic systems, the order of a reaction is not always that simple: it can be partial, neg. and function of other parameters. In order to analyze rate laws and exptl. orders of complex reaction networks, it is necessary to have a proper math. description of what the order of a reaction is. In general, chemists working in catalysis are unaware that such a math. description exists and therefore they are restricted to analyzing only extreme limit cases of rate laws. This manuscript offers a description and a simple demonstration of this concept, known as elasticity coeff. or normalized sensitivity. It also presents several examples of applications on classic and usual catalytic scenarios.
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Geometry optimizations were carried out using Gaussian 09 at the B3LYP-D3/6-31G(d,p) level of theory in toluene (SMD). Single point energy calculations were performed on the resulting structures employing B3LYP-D3/6-311+G(d,p)/SMD(toluene). See the Supporting Information for an overview of all computed structures. Refer to ref (12c) for an excellent discussion of alternative computational methods (functionals, basis sets, solvent models) in the context of chiral phosphate–iminium ion pairs.
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This step is assumed to be enantiodetermining on the basis of previous DFT calculations for the same reactions (refs (26) and (27e)).
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Lorenzo Carli, Anyawan Tapdara, Jianwen Jin, Yichao Zhao, Philip Wai Hong Chan. Chiral counteranion controlled chemoselectivity in gold catalysed hydroamination/enantioselective formal 1,3-allylic alcohol isomerisation of β-amino-1,4-enynols. Tetrahedron Chem 2023, 7 , 100043. https://doi.org/10.1016/j.tchem.2023.100043
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Yunliang Yu, Nazarii Sabat, Meriem Daghmoum, Zhenhao Zhang, Pascal Retailleau, Gilles Frison, Angela Marinetti, Xavier Guinchard. Enantioselective Au( i )-catalyzed tandem reactions between 2-alkynyl enones and naphthols by the tethered counterion-directed catalysis strategy. Organic Chemistry Frontiers 2023, 10 (12) , 2936-2942. https://doi.org/10.1039/D3QO00415E
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Journal of the American Chemical Society

Cite this: J. Am. Chem. Soc. 2022, 144, 8, 3497–3509

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https://doi.org/10.1021/jacs.1c11978

Published February 9, 2022

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Abstract
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Scheme 1
Scheme 1. Asymmetric Counterion-Directed Gold Catalysis
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Scheme 2
Scheme 2. Design for Asymmetric H-Bonded Counterion-Directed Au(I) Catalysis
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Scheme 3
Scheme 3. Synthesis of Phosphino(thio)urea Au(I) Chloride Complexes Au1–13^a
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^aSelected X-ray structures displayed with ORTEP ellipsoid at 50% probability level; solvent molecules and selected H atoms omitted for clarity.
Scheme 4
Scheme 4. Synthesis of Ag(I), Na(I), and Cu(II) Chiral Salts^a
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^aX-ray structure displayed with ORTEP ellipsoid at 50% probability level; binaphthol scaffold and toluene in wireframe; selected solvent molecules and all H atoms omitted for clarity.
Scheme 5
Scheme 5. Enantioselective Formal [4 + 2] Cycloadditions of 1,6-Enynes Based on 5-exo-dig Cyclizations^a
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^aReactions performed under Ar or N₂ in anhydrous toluene (0.1 or 0.2 M), unless otherwise stated. Yields of material isolated after purification, er determined by HPLC or SFC on chiral stationary phase.
^bCarried out at 2 mmol scale, with 1 mol % Au10 and 1 mol % Ag6, in technical-grade toluene (0.6 M) under air for 24 h.
^cAt 23 °C.
^dAt 0 °C.
^eWith 10 mol % Au10 and 10 mol % Ag6.
^fIncluding 5% of inseparable 6-endo-isomer.
^gReaction time: 96 h.
Scheme 6
Scheme 6. Enantioselective 6-endo-dig Cyclizations of 1,6-Enynes without (A) or with (B) Nucleophile Addition^a
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^aYields of material isolated after purification, er determined by HPLC or SFC on chiral stationary phase.
^bFor 48 h.
^cAt 23 °C.
Scheme 7
Scheme 7. Derivatization and Scope Extension
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^aPrepared from a batch of 6f with 93:7 er (see Supporting Information).
Scheme 8
Scheme 8. Enantioselective Cycloisomerization–Indole Addition to 2-Alkynyl Enones^a
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^aYields of material isolated after purification, er determined by HPLC or SFC on chiral stationary phase.
Scheme 9
Scheme 9. Synthesis of Complexes with Ureaphosphine L10
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Scheme 10
Scheme 10. Mechanistic Investigations: (A) Enantiofacial Selectivity, (B) Study of Nonlinear Effects, (C) Use of Complex Au4 as Au10 Surrogate, (D) ¹H NMR Titration of Au4 with (R)-Na6 (298 K, CD₂Cl₂), (E–J) Kinetic Studies
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Scheme 11
Scheme 11. Proposed Mechanism for the Cyclization of Enyne 1 under H-Bonded Counterion-Directed Au(I) Catalysis
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References
This article references 52 other publications.
1. 1
  Hamilton, G. L.; Kang, E. J.; Mba, M.; Toste, F. D. A Powerful Chiral Counterion Strategy for Asymmetric Transition Metal Catalysis. Science 2007, 317, 496– 499, DOI: 10.1126/science.1145229
  1
  A powerful chiral counterion strategy for asymmetric transition metal catalysis
  Hamilton, Gregory L.; Kang, Eun Joo; Mba, Miriam; Toste, F. Dean
  Science (Washington, DC, United States) (2007), 317 (5837), 496-499CODEN: SCIEAS; ISSN:0036-8075. (American Association for the Advancement of Science)
  Traditionally, transition metal-catalyzed enantioselective transformations rely on chiral ligands tightly bound to the metal to induce asym. product distributions. High enantioselectivities conferred by a chiral counterion in a metal-catalyzed reaction are reported. Two different transformations catalyzed by cationic gold(I) complexes generated products in 90 to 99% enantiomeric excess with the use of chiral binaphthol-derived phosphate anions. Furthermore, the chiral counterion can be combined additively with chiral ligands to enable an asym. transformation that cannot be achieved by either method alone. This concept of relaying chiral information via an ion pair should be applicable to a vast no. of metal-mediated processes.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXotFyltbw%253D&md5=cf133b6947d52ee483d9be3ded331feb
2. 2
  (a) Mayer, S.; List, B. Asymmetric Counteranion-Directed Catalysis. Angew. Chem. Int. Ed. 2006, 45, 4193– 4195, DOI: 10.1002/anie.200600512
  2a
  Asymmetric counteranion-directed catalysis
  Mayer, Sonja; List, Benjamin
  Angewandte Chemie, International Edition (2006), 45 (25), 4193-4195CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Exceedingly high enantioselectivity in a catalytic reaction can be realized even when the chirality resides only in the counteranion of the catalyst. A salt composed of an achiral ammonium cation and a chiral binaphthalenediyl phosphate counteranion catalyzes asym. transfer hydrogenations of arom. and aliph. α,β-unsatd. aldehydes with a Hantzsch ester in excellent enantioselectivities.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XmsFyntrY%253D&md5=b5688d6aa76f6b9dc94b0ec710954166
  (b) Mukherjee, S.; List, B. Chiral Counteranions in Asymmetric Transition-Metal Catalysis: Highly Enantioselective Pd/Brønsted Acid-Catalyzed Direct α-Allylation of Aldehydes. J. Am. Chem. Soc. 2007, 129, 11336– 11337, DOI: 10.1021/ja074678r
  2b
  Chiral Counteranions in Asymmetric Transition-Metal Catalysis: Highly Enantioselective Pd/Bronsted Acid-Catalyzed Direct α-Allylation of Aldehydes
  Mukherjee, Santanu; List, Benjamin
  Journal of the American Chemical Society (2007), 129 (37), 11336-11337CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  A highly enantioselective Pd/chiral phosphoric acid-catalyzed α-allylation of α-branched aldehydes R1R2CHCHO (R1 = Me, R2 = Ph, 4-MeC6H4, 3-FC6H4, 2-naphthyl, cyclohexyl, 2-thienyl; R2R2 = 2-C6H4CH2CH2) with allylic amines R3CH:CHCH2NHR4 (R3 = H, Me, Ph, R4 = Ph2CH; R3 = H, R4 = PhCH2, 3,5-Me2C6H3CH2, etc.) as the allylating species that creates all-carbon quaternary stereogenic centers in high yields and enantioselectivities has been developed. To our knowledge, this is the first time that a chiral anionic ligand is applied for achieving asym. induction in a palladium-catalyzed allylic alkylation reaction.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsVeltL0%253D&md5=ab3844e9ac4b8206ede7bbe3f70a020d
  (c) Phipps, R. J.; Hamilton, G. L.; Toste, F. D. The Progression of Chiral Anions from Concepts to Applications in Asymmetric Catalysis. Nat. Chem. 2012, 4, 603– 614, DOI: 10.1038/nchem.1405
  2c
  The progression of chiral anions from concepts to applications in asymmetric catalysis
  Phipps, Robert J.; Hamilton, Gregory L.; Toste, F. Dean
  Nature Chemistry (2012), 4 (8), 603-614CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
  A review. Despite the tremendous advances of the past four decades, chemists are far from being able to use chiral catalysts to control the stereoselectivity of any desired reaction. New concepts for the construction and mode of operation of chiral catalysts have the potential to open up previously inaccessible reaction space. The recognition and categorization of distinct approaches seems to play a role in triggering rapid exploration of new territory. This review both reflects on the origins as well as details a selection of the latest examples of an area that has advanced considerably within the past five years or so: the use of chiral anions in asym. catalysis. Defining reactions as involving chiral anions is a difficult task owing to uncertainties over the exact catalytic mechanisms. Nevertheless, the authors attempted to provide an overview of the breadth of reactions that could reasonably fall under this umbrella.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVOis7fL&md5=df30abefc42ad58cf9016f4cdb68f1ac
  (d) Mahlau, M.; List, B. Asymmetric Counteranion-Directed Catalysis: Concept, Definition, and Applications. Angew. Chem., Int. Ed. 2013, 52, 518– 533, DOI: 10.1002/anie.201205343
  2d
  Asymmetric Counteranion-Directed Catalysis: Concept, Definition, and Applications
  Mahlau, Manuel; List, Benjamin
  Angewandte Chemie, International Edition (2013), 52 (2), 518-533CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Recently, the use of enantiomerically pure counter anions for the induction of asymmetry in reactions proceeding through cationic intermediates has emerged as an exciting new concept, which has been termed asym. counteranion-directed catalysis (ACDC). Despite its success, the concept has not been fully defined and systematically discussed to date. This Review closes this gap by providing a clear definition of ACDC and by examg. both clear cases as well as more ambiguous examples to illustrate the differences and overlaps with other catalysis concepts.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslKmtr3L&md5=45faead19031c7cd7facbe5c8a2c0565
  (e) Brak, K.; Jacobsen, E. N. Asymmetric Ion-Pairing Catalysis. Angew. Chem., Int. Ed. 2013, 52, 534– 561, DOI: 10.1002/anie.201205449
  2e
  Asymmetric ion-pairing catalysis
  Brak, Katrien; Jacobsen, Eric N.
  Angewandte Chemie, International Edition (2013), 52 (2), 534-561CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Charged intermediates and reagents are ubiquitous in org. transformations. The interaction of these ionic species with chiral neutral, anionic, or cationic small mols. emerged as a powerful strategy for catalytic, enantioselective synthesis. This review described developments in the burgeoning field of asym. ion-pairing catalysis with an emphasis on the insights that were gleaned into the structural and mechanistic features that contribute to high asym. induction.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhslKmtr3E&md5=0221ea269c66cfec291e427012d7fbfb
  (f) Shirakawa, S.; Maruoka, K. Recent Developments in Asymmetric Phase-Transfer Reactions. Angew. Chem., Int. Ed. 2013, 52, 4312– 4348, DOI: 10.1002/anie.201206835
  2f
  Recent Developments in Asymmetric Phase-Transfer Reactions
  Shirakawa, Seiji; Maruoka, Keiji
  Angewandte Chemie, International Edition (2013), 52 (16), 4312-4348CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Phase-transfer catalysis has been recognized as a powerful method for establishing practical protocols for org. synthesis, because it offers several advantages, such as operational simplicity, mild reaction conditions, suitability for large-scale synthesis, and the environmentally benign nature of the reaction system. A wide variety of asym. transformations catalyzed by chiral onium salts and crown ethers have been developed for the synthesis of valuable org. compds. in the past several decades, esp. in recent years.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXjtlagtL4%253D&md5=c6ded2f09ac53af91e7f250db39c9fe9
3. 3
  For work on the combination of achiral Au(I) complexes and chiral anions, see the following:
  (a) Reference (1).
  There is no corresponding record for this reference.
  (b) LaLonde, R. L.; Wang, Z. J.; Mba, M.; Lackner, A. D.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Synthesis of Pyrazolidines, Isoxazolidines, and Tetrahydrooxazines. Angew. Chem., Int. Ed. 2010, 49, 598– 601, DOI: 10.1002/anie.200905000
  3b
  Gold(I)-catalyzed enantioselective synthesis of pyrazolidines, isoxazolidines, and tetrahydrooxazines
  Lalonde R L; Wang Z J; Mba M; Lackner A D; Toste F Dean
  Angewandte Chemie (International ed. in English) (2010), 49 (3), 598-601 ISSN:.
  There is no expanded citation for this reference.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC3c%252FitVenuw%253D%253D&md5=b065f4ea0ac0716de82658c15be4a5ec
  (c) Zi, W.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Desymmetrization of 1,3-Diols through Intramolecular Hydroalkoxylation of Allenes. Angew. Chem., Int. Ed. 2015, 54, 14447– 14451, DOI: 10.1002/anie.201508331
  3c
  Gold(I)-Catalyzed Enantioselective Desymmetrization of 1,3-Diols through Intramolecular Hydroalkoxylation of Allenes
  Zi, Weiwei; Toste, F. Dean
  Angewandte Chemie, International Edition (2015), 54 (48), 14447-14451CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A gold(I)-catalyzed enantioselective desymmetrization of 1,3-diols was achieved by intramol. hydroalkoxylation of allenes. The catalyst system 3-F-dppe(AuCl)2/(R)-C8-TRIPAg proved to be specifically efficient to promote the desymmetrizing cyclization of 2-aryl-1,3-diols, which have proven challenging substrates in previous reports [e.g., diol I → THF II (>95% yield, d.r. > 25:1, ee 93%) in presence of L(AuCl2)/AgX*, where L = III and AgX* = IV]. Multisubstituted tetrahydrofurans were prepd. in good yield with good enantioselectivity and diastereoselectivity by this method.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhsF2ksrbN&md5=fd955d1383ee88c56adf12d45bf28eb9
  (d) Pedrazzani, R.; An, J.; Monari, M.; Bandini, M. New Chiral BINOL-Based Phosphates for Enantioselective [Au(I)]-Catalyzed Dearomatization of β-Naphthols with Allenamides. Eur. J. Org. Chem. 2021, 2021, 1732– 1736, DOI: 10.1002/ejoc.202100166
  3d
  New Chiral BINOL-Based Phosphates for Enantioselective [Au(I)]-Catalyzed Dearomatization of β-Naphthols with Allenamides
  Pedrazzani, Riccardo; An, Juzeng; Monari, Magda; Bandini, Marco
  European Journal of Organic Chemistry (2021), 2021 (11), 1732-1736CODEN: EJOCFK; ISSN:1099-0690. (Wiley-VCH Verlag GmbH & Co. KGaA)
  New chiral BINOL-based phosphate counterions have been synthesized, fully characterized, and employed in the enantioselective gold-catalyzed dearomatization of β-naphthols with allenamides. A range of densely functionalized C1-allylated naphthalenones were realized under mild conditions and high levels of chemo-, regio- and stereoselectivity (ee up to 95%).
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmvFGrtLs%253D&md5=c235fc472d5fc0aadc013ea7db5802de
4. 4
  For work on the combination of chiral Au(I) complexes and chiral anions, see the following:
  (a) Aikawa, K.; Kojima, M.; Mikami, K. Axial Chirality Control of Gold(biphep) Complexes by Chiral Anions: Application to Asymmetric Catalysis. Angew. Chem., Int. Ed. 2009, 48, 6073– 6077, DOI: 10.1002/anie.200902084
  4a
  Axial Chirality Control of Gold(biphep) Complexes by Chiral Anions: Application to Asymmetric Catalysis
  Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
  Angewandte Chemie, International Edition (2009), 48 (33), 6073-6077, S6073/1-S6073/47CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The axial chirality of tropos gold-biphep (biphep = bis(phosphanyl)biphenyl) complexes can be controlled by chiral anions (S)-I (Ar = Ph; 4-PhC6H4; 2,4,6-tri-iPrC6H2; 2-naphthyl; etc.), and the chirality is imprinted and memorized even after the dissocn. of I. The enantiopure complexes thus obtained efficiently function as axially chiral asym. catalysts in an intramol. hydroamination reaction of (aminoalkyl)allene derivs. to yield enantiomerically enriched pyrrolidines.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1MXptlCjt7k%253D&md5=89bd01f2ead534e211c313429db20eba
  (b) Aikawa, K.; Kojima, M.; Mikami, K. Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions. Adv. Synth. Catal. 2010, 352, 3131– 3135, DOI: 10.1002/adsc.201000672
  4b
  Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions
  Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
  Advanced Synthesis & Catalysis (2010), 352 (18), 3131-3135CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A synergistic effect is obsd. for the combination of neutral dinuclear gold complex I (R1 = 3,5-di-MeC6H3) with chiral silver phosphate II in the intramol. hydroalkoxylation of allenes to give vinyltetrahydrofuran derivs. in high yields and enantioselectivities. The monocationic dinuclear gold complex affords higher catalytic activity and enantioselectivity than the neutral or dicationic digold complexes. The synergistic effect is thus highly promising to provide a guiding principle in designing an efficient chiral environment for creating an asym. catalyst.
  >> More from SciFinder ^®
  https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhsFOjs7%252FO&md5=9066e1fcebe54ec10419d8401286e49e
  Corrigendum:Aikawa, K.; Kojima, M.; Mikami, K. Adv. Synth. Catal. 2011, 353, 2882– 2883, DOI: 10.1002/adsc.201100838
  4
  Synergistic Effect: Hydroalkoxylation of Allenes through Combination of Enantiopure BIPHEP-Gold Complexes and Chiral Anions [Erratum to document cited in CA154:259297]
  Aikawa, Kohsuke; Kojima, Masafumi; Mikami, Koichi
  Advanced Synthesis & Catalysis (2011), 353 (16), 2882-2883CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Due to a stereochem. error, the article requires several configuration corrections; the cor. compds. are given.
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  (c) Barreiro, E. M.; Broggini, D. F. D.; Adrio, L. A.; White, A. J. P.; Schwenk, R.; Togni, A.; Hii, K. K. Gold(I) Complexes of Conformationally Constricted Chiral Ferrocenyl Phosphines. Organometallics 2012, 31, 3745– 3754, DOI: 10.1021/om300222k
  4c
  Gold(I) Complexes of Conformationally Constricted Chiral Ferrocenyl Phosphines
  Barreiro, Elena M.; Broggini, Diego F. D.; Adrio, Luis A.; White, Andrew J. P.; Schwenk, Rino; Togni, Antonio; Hii, King Kuok
  Organometallics (2012), 31 (9), 3745-3754CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
  The prepn. of two new chiral, enantiopure, and conformationally constrained phosphocin and 1,5-diphosphocin, incorporating two ferrocenyl units, is described. The gold(I) chloride complexes of these ligands and (S)-(R)-PPF-OMe were prepd., and their structures, in soln. and solid states, are compared. Abstraction of the chloride anion by the addn. of silver salt of either toluenesulfonate or chiral BINOL-phosphates generates active catalysts for the intramol. cyclization of 6-methyl-1,1-diphenylhepta-4,5-dien-1-ol, where up to 47% ee can be obtained. Match and mismatch effects between chiral ligands and counteranions are highlighted.
  >> More from SciFinder ^®
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  (d) Miles, D. H.; Veguillas, M.; Toste, F. D. Gold(I)-Catalyzed Enantioselective Bromocyclization Reactions of Allenes. Chem. Sci. 2013, 4, 3427– 3431, DOI: 10.1039/c3sc50811k
  4d
  Gold(I)-catalyzed enantioselective bromocyclization reactions of allenes
  Miles, Dillon H.; Veguillas, Marcos; Toste, F. Dean
  Chemical Science (2013), 4 (9), 3427-3431CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
  The enantioselective bromocyclization of allenes, e.g. I, using chiral dinuclear gold complex and/or chiral phosphate anions in presence of N-bromolactam as an electrophilic bromine source was described. The enantioselective bromocyclization provides access to heterocyclic vinyl bromides with an allylic stereocenter in excellent yield and enantioselectivity. The synthesized enantio enriched vinyl bromides II may serve as a handle for further derivatization via cross-coupling reactions.
  >> More from SciFinder ^®
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  (e) Handa, S.; Lippincott, D. J.; Aue, D. H.; Lipshutz, B. H. Asymmetric Gold-Catalyzed Lactonizations in Water at Room Temperature. Angew. Chem., Int. Ed. 2014, 53, 10658– 10662, DOI: 10.1002/anie.201404729
  4e
  Asymmetric Gold-Catalyzed Lactonizations in Water at Room Temperature
  Handa, Sachin; Lippincott, Daniel J.; Aue, Donald H.; Lipshutz, Bruce H.
  Angewandte Chemie, International Edition (2014), 53 (40), 10658-10662CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Asym. gold-catalyzed hydrocarboxylations are reported that show broad substrate scope. The hydrophobic effect assocd. with in situ-formed aq. nanomicelles gives good to excellent ee's of product lactones. In-flask product isolation, along with the recycling of the catalyst and the reaction medium, are combined to arrive at an esp. environmentally friendly process.
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5. 5
  (a) Mourad, A. K.; Leutzow, J.; Czekelius, C. Anion-Induced Enantioselective Cyclization of Diynamides to Pyrrolidines Catalyzed by Cationic Gold Complexes. Angew. Chem., Int. Ed. 2012, 51, 11149– 11152, DOI: 10.1002/anie.201205416
  5a
  Anion-induced enantioselective cyclization of diynamides to pyrrolidines catalyzed by cationic gold complexes
  Mourad, Asmaa Kamal; Leutzow, Juliane; Czekelius, Constantin
  Angewandte Chemie, International Edition (2012), 51 (44), 11149-11152CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  An enantioselective synthesis of methylene pyrrolidines via cycloisomerization of 1,4-diynamides catalyzed by cationic gold complexes is developed. The reaction used cationic gold catalyst with optically active and binol phosphates as counteranions. The best results were obtained in chlorinated solvents at low temp.
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  (b) Spittler, M.; Lutsenko, K.; Czekelius, C. Total Synthesis of (+)-Mesembrine Applying Asymmetric Gold Catalysis. J. Org. Chem. 2016, 81, 6100– 6105, DOI: 10.1021/acs.joc.6b00985
  5b
  Total Synthesis of (+)-Mesembrine Applying Asymmetric Gold Catalysis
  Spittler, Michael; Lutsenko, Kiril; Czekelius, Constantin
  Journal of Organic Chemistry (2016), 81 (14), 6100-6105CODEN: JOCEAH; ISSN:0022-3263. (American Chemical Society)
  The total synthesis of enantiomerically pure (+)-mesembrine is described. The central pyrrolidine moiety incorporating a quaternary, all-carbon-substituted stereocenter was constructed employing an asym. gold-catalyzed cycloisomerization of a 1,4-diynamide.
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6. 6
  For a review on the combination of Au(I) methyl complexes and excess Brønsted acid for tandem reactions, see the following:
  (a) Inamdar, S. M.; Konala, A.; Patil, N. T. When gold meets chiral Brønsted acid catalysis: extending the boundaries of enantioselective gold catalysis. Chem. Commun. 2014, 50, 15124– 15135, DOI: 10.1039/C4CC04633A
  6a
  When gold meets chiral Bronsted acid catalysts: extending the boundaries of enantioselective gold catalysis
  Inamdar, Suleman M.; Konala, Ashok; Patil, Nitin T.
  Chemical Communications (Cambridge, United Kingdom) (2014), 50 (96), 15124-15135CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  A review; this review describes the development in the use of Au(I)/Bronsted acid binary catalytic systems to enable an enantioselective transformation in one-pot that cannot be achieved by gold catalysts alone. The examples discussed herein are promising since apart from using chiral ligands there exists a possibility of using chiral Bronsted acids. Clearly, the horizon for enantioselective gold catalysis has been expanded as more options to make the gold-catalyzed reactions enantioselective have become available.
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  For selected examples, see the following:
  (b) Han, Z.-Y.; Xiao, H.; Chen, X.-H.; Gong, L.-Z. Consecutive Intramolecular Hydroamination/Asymmetric Transfer Hydrogenation under Relay Catalysis of an Achiral Gold Complex/Chiral Brønsted Acid Binary System. J. Am. Chem. Soc. 2009, 131, 9182– 9183, DOI: 10.1021/ja903547q
  6b
  Consecutive Intramolecular Hydroamination/Asymmetric Transfer Hydrogenation under Relay Catalysis of an Achiral Gold Complex/Chiral Bronsted Acid Binary System
  Han, Zhi-Yong; Xiao, Han; Chen, Xiao-Hua; Gong, Liu-Zhu
  Journal of the American Chemical Society (2009), 131 (26), 9182-9183CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Consecutive hydroamination/asym. transfer hydrogenation under relay catalysis of an achiral gold complex/chiral Bronsted acid binary system has been described for the direct transformation of 2-(2-propynyl)aniline derivs. into tetrahydroquinolines with high enantiomeric purity.
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  (c) Muratore, M. E.; Holloway, C. A.; Pilling, A. W.; Storer, R. I.; Trevitt, G.; Dixon, D. J. Enantioselective Brønsted Acid-Catalyzed N-Acyliminium Cyclization Cascades. J. Am. Chem. Soc. 2009, 131, 10796– 10797, DOI: 10.1021/ja9024885
  6c
  Enantioselective Bronsted Acid-Catalyzed N-Acyliminium Cyclization Cascades
  Muratore, Michael E.; Holloway, Chloe A.; Pilling, Adam W.; Storer, R. Ian; Trevitt, Graham; Dixon, Darren J.
  Journal of the American Chemical Society (2009), 131 (31), 10796-10797CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  An enantioselective Bronsted acid-catalyzed N-acyliminium cyclization cascade of tryptamines with enol lactones to form architecturally complex heterocycles, i.e. I, in high enantiomeric excess has been developed. The reaction is tech. simple to perform as well as atom-efficient and may be coupled to a gold(I)-catalyzed cycloisomerization of alkynoic acids whereby the key enol lactone reaction partner is generated in situ. Employing up to 10 mol % bulky chiral phosphoric acid catalysts in boiling toluene allowed the product materials to be generated in good overall yields (63-99%) and high enantioselectivities (72-99% ee). With doubly substituted enol lactones, high diastereo- and enantioselectivities were obtained, thus providing a new example of a dynamic kinetic asym. cyclization reaction.
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  (d) Liu, X.-Y.; Che, C.-M. Highly Enantioselective Synthesis of Chiral Secondary Amines by Gold(I)/Chiral Brønsted Acid Catalyzed Tandem Intermolecular Hydroamination and Transfer Hydrogenation Reactions. Org. Lett. 2009, 11, 4204– 4207, DOI: 10.1021/ol901443b
  6d
  Highly Enantioselective Synthesis of Chiral Secondary Amines by Gold(I)/Chiral Bronsted Acid Catalyzed Tandem Intermolecular Hydroamination and Transfer Hydrogenation Reactions
  Liu, Xin-Yuan; Che, Chi-Ming
  Organic Letters (2009), 11 (18), 4204-4207CODEN: ORLEF7; ISSN:1523-7060. (American Chemical Society)
  A method for the synthesis of enantiomerically enriched secondary amines with excellent ee values through the tandem intermol. hydroamination/transfer hydrogenation of alkynes using a "gold(I) complex-chiral Bronsted acid" protocol is developed. The catalysis works for a wide variety of aryl, alkenyl, and aliph. alkynes as well as anilines with different electronic properties.
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  (e) Tu, X.-F.; Gong, L.-Z. Highly Enantioselective Transfer Hydrogenation of Quinolines Catalyzed by Gold Phosphates: Achiral Ligand Tuning and Chiral-Anion Control of Stereoselectivity. Angew. Chem., Int. Ed. 2012, 51, 11346– 11349, DOI: 10.1002/anie.201204179
  6e
  Highly Enantioselective Transfer Hydrogenation of Quinolines Catalyzed by Gold Phosphates: Achiral Ligand Tuning and Chiral-Anion Control of Stereoselectivity
  Tu, Xi-Feng; Gong, Liu-Zhu
  Angewandte Chemie, International Edition (2012), 51 (45), 11346-11349CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The authors have found that chiral gold phosphate complexes are able to serve as highly efficient catalysts for the asym. transfer hydrogenation of 2-arylquinolines with the stereoselectivity being controlled by the chiral anion. Only 0.01 mol. % of the gold phosphate is needed to effectively afford the highly enantioselective transfer hydrogenation of 2-arylquinolines. Tuning of the achiral ligand IMes as in [IMesAuMe] had a great impact on the catalytic activity, with the chiral gold phosphate exhibiting high catalytic efficiency when the carbene IMes was used as a ligand.
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  (f) Cala, L.; Mendoza, A.; Fañanás, F. J.; Rodríguez, F. A Catalytic Multicomponent Coupling Reaction for the Enantioselective Synthesis of Spiroacetals. Chem. Commun. 2013, 49, 2715– 2717, DOI: 10.1039/c3cc00118k
  6f
  A catalytic multicomponent coupling reaction for the enantioselective synthesis of spiroacetals
  Cala, Lara; Mendoza, Abraham; Fananas, Francisco J.; Rodriguez, Felix
  Chemical Communications (Cambridge, United Kingdom) (2013), 49 (26), 2715-2717CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  The first multicomponent catalytic asym. synthesis of spiroacetals has been described. Hybrid mols. comprising a spiroacetal scaffold (a natural-product inspired scaffold) and an α-amino acid motif (a privileged fragment) are easily available through a gold phosphate-catalyzed one-pot three component coupling reaction of alkynols, anilines and glyoxylic acid.
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  (g) Zhou, S.; Li, Y.; Liu, X.; Hu, W.; Ke, Z.; Xu, X. Enantioselective Oxidative Multi-Functionalization of Terminal Alkynes with Nitrones and Alcohols for Expeditious Assembly of Chiral α-Alkoxy-β-amino-ketones. J. Am. Chem. Soc. 2021, 143, 14703– 14711, DOI: 10.1021/jacs.1c06178
  6g
  Enantioselective Oxidative Multi-Functionalization of Terminal Alkynes with Nitrones and Alcohols for Expeditious Assembly of Chiral α-Alkoxy-β-amino-ketones
  Zhou, Su; Li, Yinwu; Liu, Xiangrong; Hu, Wenhao; Ke, Zhuofeng; Xu, Xinfang
  Journal of the American Chemical Society (2021), 143 (36), 14703-14711CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Catalytic oxidative functionalization of alkynes has emerged as an effective method in synthetic chem. in recent decades. However, enantioselective transformations via metal carbene intermediates are quite rare due to the lack of robust chiral catalysts, esp. in the intermol. versions. Herein, the first asym. three-component reaction of com. available alkynes with nitrones and alcs., which affords α-alkoxy-β-amino-ketones in good yields with high to excellent enantioselectivity using combined catalysis by achiral gold-complex and chiral spiro phosphoric acid (CPA) is reported. Mechanistically, this atom-economic reaction involves a catalytic alkyne oxidn./ylide formation/Mannich-type addn. sequence that uses nitrone as the oxidant and the leaving fragment imine as the electrophile, providing a novel method for multifunctionalization of com. available terminal alkynes.
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7. 7
  (a) Dorel, R.; Echavarren, A. M. Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity. Chem. Rev. 2015, 115, 9028– 9072, DOI: 10.1021/cr500691k
  7a
  Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity
  Dorel, Ruth; Echavarren, Antonio M.
  Chemical Reviews (Washington, DC, United States) (2015), 115 (17), 9028-9072CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. In this review, the authors cover reactions of alkynes activated by gold(I) complexes, including recent applications of these transformations in the synthesis of natural products. The main focus is on the application of gold(I)-catalyzed reactions of alkynes in org. synthesis, and the reactions are organized mechanistically. Reactions of gold(I)-activated alkenes and allenes, as well as gold(III)-activated alkynes, are not covered in this review.
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  (b) Zuccarello, G.; Escofet, I.; Caniparoli, U.; Echavarren, A. M. New-Generation Ligand Design for the Gold Catalyzed Asymmetric Activation of Alkynes. ChemPlusChem 2021, 86, 1283– 1296, DOI: 10.1002/cplu.202100232
  7b
  New-Generation Ligand Design for the Gold-Catalyzed Asymmetric Activation of Alkynes
  Zuccarello, Giuseppe; Escofet, Imma; Caniparoli, Ulysse; Echavarren, Antonio M.
  ChemPlusChem (2021), 86 (9), 1283-1296CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Herein the recent advances in intra- and intermol. enantioselective gold(I)-catalyzed reactions involving alkynes was summarized, discussing new chiral ligand designs that lie at the basis of these developments. The mode of action of these catalysts, their possible limitations towards a next-generation of more efficient ligand designs was discussed. Finally, square planar chiral gold(III) complexes, which offer an alternative to chiral gold(I) complexes, are also discussed.
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  (c) Barbazanges, M.; Augé, M.; Moussa, J.; Amouri, H.; Aubert, C.; Desmarets, C.; Fensterbank, L.; Gandon, V.; Malacria, M.; Ollivier, C. Enantioselective Ir^I-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy. Chem.─Eur. J. 2011, 17, 13789– 13794, DOI: 10.1002/chem.201102723
  7c
  Enantioselective IrI-Catalyzed Carbocyclization of 1,6-Enynes by the Chiral Counterion Strategy
  Barbazanges, Marion; Auge, Mylene; Moussa, Jamal; Amouri, Hani; Aubert, Corinne; Desmarets, Christophe; Fensterbank, Louis; Gandon, Vincent; Malacria, Max; Ollivier, Cyril
  Chemistry - A European Journal (2011), 17 (49), 13789-13794, S13789/1-S13789/71CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Enantioenriched heterobicyclo[4.1.0]hept-2-enes were synthesized by IrI-catalyzed carbocyclization of 1,6-enynes. No chiral ligands were used; CO and PPh3 were the only ligands bound to iridium. Instead, the stereochem. information was localized on the counterion of the catalyst, generated in situ by reaction of Vaska's complex (trans-[IrCl(CO)(PPh3)2]) with a chiral silver phosphate. Enantiomeric excesses up to 93 % were obtained when this catalytic mixt. was used. 31P NMR and IR spectroscopy suggest that formation of the trans- [Ir(CO)(PPh3)2]+ moiety occurs by chlorine abstraction. Moreover, d. functional theory calcns. support a 6-endo-dig cyclization promoted by this cationic moiety. The chiral phosphate anion (O-P*) controls the enantioselectivity through formation of a loose ion pair with the metal center and establishes a C-H···O-P* hydrogen bond with the substrate. This is a rare example of asym. counterion-directed transition-metal catalysis and represents the first application of such a strategy to a C-C bond-forming reaction.
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8. 8
  Raducan, M.; Moreno, M.; Bour, C.; Echavarren, A. M. Phosphate Ligands in the Gold(I)-Catalysed Activation of Enynes. Chem. Commun. 2012, 48, 52– 54, DOI: 10.1039/C1CC15739F
  8
  Phosphate ligands in the gold(I)-catalyzed activation of enynes
  Raducan, Mihai; Moreno, Maria; Bour, Christophe; Echavarren, Antonio M.
  Chemical Communications (Cambridge, United Kingdom) (2012), 48 (1), 52-54CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  Au(I) forms neutral complexes with binol phosphates, e.g., I (R = SiPh3, 2,4,6-iPr3C6H2), that are unreactive in the catalytic cyclization of enynes. However, reactions in protic solvents or with activation by Ag(I) restores the catalytic activity of, e.g., I.
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9. 9
  For reviews, see the following:
  (a) Jia, M.; Bandini, M. Counterion Effects in Homogeneous Gold Catalysis. ACS Catal. 2015, 5, 1638– 1652, DOI: 10.1021/cs501902v
  9a
  Counterion Effects in Homogeneous Gold Catalysis
  Jia, Minqiang; Bandini, Marco
  ACS Catalysis (2015), 5 (3), 1638-1652CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
  A review. Homogeneous gold catalysis has received growing attention over the past few years, enabling the replacement of consolidated org. reactions with more simple, selective, and chem. sustainable alternatives. The fine-tunability of the electronic as well as steric properties of gold catalysts contributed substantially to the popularity of the research field, with robust applications in total synthesis and asym. catalysis. In this context, the metal counterions proved of pivotal importance in impacting both kinetics and selectivity of gold-assisted transformations. Despite the intrinsic difficulties in properly rationalizing and predicting the role of anions in complex reaction machineries, nowadays, some general trends are available. This review aims at presenting some leading examples of counterion-controlled gold catalysis, with particular emphasis on their structure-activity relationship.
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  (b) Zuccaccia, D.; Del Zotto, A.; Baratta, W. The Pivotal Role of the Counterion in Gold Catalyzed Hydration and Alkoxylation of Alkynes. Coord. Chem. Rev. 2019, 396, 103– 116, DOI: 10.1016/j.ccr.2019.06.007
  9b
  The pivotal role of the counterion in gold catalyzed hydration and alkoxylation of alkynes
  Zuccaccia, D.; Del Zotto, A.; Baratta, W.
  Coordination Chemistry Reviews (2019), 396 (), 103-116CODEN: CCHRAM; ISSN:0010-8545. (Elsevier B.V.)
  A review. Hydration and alkoxylation of alkynes are key processes for the industrial prodn. of carbonyl derivs. In this review, the pivotal role of ion pairing in the mechanism of hydration and alkoxylation of alkynes promoted by gold(I) catalysts L-Au-X is deeply analyzed and discussed, that has been elucidated by means of exptl. findings supported by some theor. calcns. In particular, the crucial role of the counterion X- is fully described in chapter 2. The catalytic performances in the alkoxylation and hydration of alkynes promoted by gold(I) are influenced by the coordination ability and basicity (proton affinity) of the counterion (paragraph 2.3) and the anion/cation relative orientation (paragraph 2.3). Also the appropriate matching of X- and the neutral ligand L must be taken into account to improve the catalytic performance of gold catalysts (paragraph 2.4). A survey of other non-covalent interactions, which however play a kinetic important role (hydrogen bonds, those triggered by suitable functionalities present on the ligand L, formation of supramol. catalytic systems or micelles, and others), is presented in chapter 3. The progress in the development of sustainable methodologies for the gold(I)-promoted hydration of alkynes is discussed in chapter 4. In particular, paragraph 4.1 focuses on the unique role played by the anion in the L-Au-X catalyzed hydration of alkynes conducted in solvent-, silver-, and acid-free conditions. To conclude this crit. review, in paragraph 4.2 it is highlighted how the amt. of ion pairing, combined with the presence of suitable functionalities in neoteric solvent, may allow the development of green protocols for gold(I) catalyzed hydration of alkynes.
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  (c) Lu, Z.; Li, T.; Mudshinge, S. R.; Xu, B.; Hammond, G. B. Optimization of Catalysts and Conditions in Gold(I) Catalysis─Counterion and Additive Effects. Chem. Rev. 2021, 121, 8452– 8477, DOI: 10.1021/acs.chemrev.0c00713
  9c
  Optimization of Catalysts and Conditions in Gold(I) Catalysis - Counterion and Additive Effects
  Lu, Zhichao; Li, Tingting; Mudshinge, Sagar R.; Xu, Bo; Hammond, Gerald B.
  Chemical Reviews (Washington, DC, United States) (2021), 121 (14), 8452-8477CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. Leading examples of counterion or additive-regulated gold catalysis from a mechanistic perspective were presented. Special attention to the phys. properties of counterion/additive, such as gold affinity and hydrogen bond basicity, and discuss their effects on the reactivity of gold catalysts were paid.
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10. 10
  For selected articles, see the following:
  (a) Zuccaccia, D.; Belpassi, L.; Tarantelli, F.; Macchioni, A. Ion Pairing in Cationic Olefin-Gold(I) Complexes. J. Am. Chem. Soc. 2009, 131, 3170– 3171, DOI: 10.1021/ja809998y
  10a
  Ion Pairing in Cationic Olefin-Gold(I) Complexes
  Zuccaccia, Daniele; Belpassi, Leonardo; Tarantelli, Francesco; Macchioni, Alceo
  Journal of the American Chemical Society (2009), 131 (9), 3170-3171CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The relative anion-cation orientation in [(PPh3)Au(4-Me-styrene)]BF4 (1BF4) and [(NHC)Au(4-Me-styrene)]BF4 [2BF4; NHC = 1,3-bis(di-iso-propylphenyl)-imidazol-2-ylidene] was studied by combining 19F,1H-HOESY NMR spectroscopy and D. Functional Theory (DFT) calcns. incorporating solvent and relativistic effects. BF4- locates on the side of 4-Me-styrene, close to the olefin region that is opposite to the 4-Me-Ph moiety in 1BF4. In 2BF4, the counterion approaches the cation from the side of the NHC ligand and is mainly located close to the imidazole ring. In both cases, the counterion resides far away from the Au site, the latter carrying only a small fraction of the pos. charge. The preferential position of the counterion is tunable through the choice of the ancillary ligand, and this opens the way to greater control over the properties and activity of these catalysts.
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  (b) Zuccaccia, D.; Belpassi, L.; Rocchigiani, L.; Tarantelli, F.; Macchioni, A. A Phosphine Gold(I) π-Alkyne Complex: Tuning the Metal-Alkyne Bond Character and Counterion Position by the Choice of the Ancillary Ligand. Inorg. Chem. 2010, 49, 3080– 3082, DOI: 10.1021/ic100093n
  10b
  A phosphine gold(I) π-alkyne complex: tuning the metal-alkyne bond character and counterion position by the choice of the ancillary ligand
  Zuccaccia, Daniele; Belpassi, Leonardo; Rocchigiani, Luca; Tarantelli, Francesco; Macchioni, Alceo
  Inorganic Chemistry (2010), 49 (7), 3080-3082CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
  Gold-alkyne bonding was investigated in dependence on an ancillary ligands, electron-deficient phosphine and 2-imidazolylidene NHC carbene, by NMR spectroscopy and DFT calcns. The intra- and interionic structures of a mononuclear phosphine gold(I) alkyne complex [(PArF3)Au(2-hexyne)]BF4 [1·BF4; ArF = 3,5-(CF3)2C6H3] and its analogous complex [(NHC)Au(2-hexyne)]BF4 [2·BF4; NHC = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene] have been investigated by combining 1D and 2D multinuclear NMR spectroscopy and d. functional theory calcns. It has been found that alkyne in 1·BF4 is depleted of its electron d. to a greater extent than that in 2·BF4. This correlates with the Δδ(13C) NMR of the carbon-carbon triple bond. Instead, 2·BF4 is much more kinetically stable than 1·BF4. NMR 19F-1H HOESY spectra indicate that the counterion locates close to the gold atom in 1·BF4 (differently from that previously obsd. in the few other gold(I) ion pairs studied), exactly where the computed Coulomb potential indicates that partial pos. charge accumulates.
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  (c) Bandini, M.; Bottoni, A.; Chiarucci, M.; Cera, G.; Miscione, G. P. Mechanistic Insights into Enantioselective Gold-Catalyzed Allylation of Indoles with Alcohols: The Counterion Effect. J. Am. Chem. Soc. 2012, 134, 20690– 20700, DOI: 10.1021/ja3086774
  10c
  Mechanistic Insights into Enantioselective Gold-Catalyzed Allylation of Indoles with Alcohols: The Counterion Effect
  Bandini, Marco; Bottoni, Andrea; Chiarucci, Michel; Cera, Gianpiero; Miscione, Gian Pietro
  Journal of the American Chemical Society (2012), 134 (51), 20690-20700CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Enantioselective gold-catalysis is emerging as a powerful tool in org. synthesis for the stereoselective manipulation of unfunctionalized unsatd. hydrocarbons. Despite the exponential growth, the mol. complexity of common chiral gold complexes generally prevents a complete description of the mechanism steps and activation modes being documented. In this study, we present the results of a combined exptl.-computational (DFT) investigation of the mechanism of the enantioselective gold-catalyzed allylic alkylation of indoles with alcs. A stepwise SN2'-process (i.e. anti-auroindolination of the olefin, proton-transfer, and subsequent anti-elimination [Au]-OH) is disclosed, leading to a library of tricyclic-fused indole derivs. The pivotal role played by the gold counterion, in terms of mol. arrangement (i.e. "folding effect") and proton-shuttling in restoring the catalytic species, is finally documented.
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  (d) Zhdanko, A.; Maier, M. E. Explanation of Counterion Effects in Gold(I)-Catalyzed Hydroalkoxylation of Alkynes. ACS Catal. 2014, 4, 2770– 2775, DOI: 10.1021/cs500446d
  10d
  Explanation of Counterion Effects in Gold(I)-Catalyzed Hydroalkoxylation of Alkynes
  Zhdanko, Alexander; Maier, Martin E.
  ACS Catalysis (2014), 4 (8), 2770-2775CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
  Using gold(I)-catalyzed hydroalkoxylation of alkynes as a model reaction with a well-known mechanism, a systematic exptl. study was conducted to disclose the influence of the counterion X- of a gold catalyst LAuNCMe+ X- on every step of the catalytic cycle. The overall ion effect is detd. as a superposition of several effects, operating on different steps of the reaction mechanism. All effects were explained from a position of hydrogen bonding, coordination chem. at gold, and affinity for a proton.
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  (e) Biasiolo, L.; Del Zotto, A.; Zuccaccia, D. Toward Optimizing the Performance of Homogeneous L-Au-X Catalysts through Appropriate Matching of the Ligand (L) and Counterion (X^–). Organometallics 2015, 34, 1759– 1765, DOI: 10.1021/acs.organomet.5b00308
  10e
  Toward optimizing the performance of homogeneous L-Au-X catalysts through appropriate matching of the ligand (L) and counterion (X-)
  Biasiolo, Luca; Del Zotto, Alessandro; Zuccaccia, Daniele
  Organometallics (2015), 34 (9), 1759-1765CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
  A set of 16 gold complexes of the type L-Au-X [L = PPh3, PtBu3, P[3,5-(CF3)2C6H3]3, 1,3-bis(2,6-diisopropylphenyl)-2-imidazolylidene (IPr); X = BF4-, OTf, OTs, CF3CO2] was prepd. and evaluated for their catalytic activity in cyclization of N-propargylbenzamide into 2-phenyl-5-methyleneoxazoline as a model for cycloisomerization of unsatd. amides into nitrogen heterocycles and methoxylation of 3-hexyne; the substituent effects were controlled by varying the electron withdrawing ability coordinating ability, basicity, and hydrogen bond acceptor power of the ligand and X groups. The effects of the ligand (L) and counterion (X-) are considered the two most important factors in homogeneous gold catalysis, but a rational understanding of their synergy/antagonism is still lacking. The main results are that the choice of the most efficient L-Au-X catalyst for a given process should not be made by evaluating the properties of L and X- alone, but rather based on their best combination. For NHC-Au-X, the noncoordinating and weakly basic anions (such as BF4- and OTf-) have been recognized as the best choice for the cycloisomerization of N-(propargyl)benzamide. On the other side, the intermediate coordinating ability and basicity of OTs- provide the best compromise for achieving an efficient methoxylation of 3-hexyne. A completely different trend is found in the case of complexes bearing phosphines: OTs- and TFA- have been found to accelerate the cycloisomerization of N-(propargyl)benzamide, and BF4- and OTf- are suitable for the methoxylation of 3-hexyne. A possible explanation of the obsd. differences between phosphine and NHC ancillary ligands might be found in the higher affinity of the counterion (esp. OTs-) for the gold fragment for phosphane instead of NHC.
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  (f) Lu, Z.; Han, J.; Okoromoba, O. E.; Shimizu, N.; Amii, H.; Tormena, C. F.; Hammond, G. B.; Xu, B. Predicting Counterion Effects Using a Gold Affinity Index and a Hydrogen Bonding Basicity Index. Org. Lett. 2017, 19, 5848– 5851, DOI: 10.1021/acs.orglett.7b02829
  10f
  Predicting Counterion Effects Using a Gold Affinity Index and a Hydrogen Bonding Basicity Index
  Lu, Zhichao; Han, Junbin; Okoromoba, Otome E.; Shimizu, Naoto; Amii, Hideki; Tormena, Claudio F.; Hammond, Gerald B.; Xu, Bo
  Organic Letters (2017), 19 (21), 5848-5851CODEN: ORLEF7; ISSN:1523-7052. (American Chemical Society)
  We have developed a gold affinity index and hydrogen bonding basicity index for counterions and have used these indexes to forecast their reactivity in cationic gold catalysis.
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  (g) Schießl, J.; Schulmeister, J.; Doppiu, A.; Wörner, E.; Rudolph, M.; Karch, R.; Hashmi, A. S. K. An Industrial Perspective on Counter Anions in Gold Catalysis: Underestimated with Respect to “Ligand Effects”. Adv. Synth. Catal. 2018, 360, 2493– 2502, DOI: 10.1002/adsc.201800233
  10g
  An Industrial Perspective on Counter Anions in Gold Catalysis: Underestimated with Respect to "Ligand Effects"
  Schiessl, Jasmin; Schulmeister, Juergen; Doppiu, Angelino; Woerner, Eileen; Rudolph, Matthias; Karch, Ralf; Hashmi, A. Stephen K.
  Advanced Synthesis & Catalysis (2018), 360 (13), 2493-2502CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The conversion of a variety of well-known test reactions, representing the key reactivity patterns of gold catalysis, were analyzed by GC and 1H NMR. The study is focused on establishing of a strategical approach for the consideration of ligand influence and counter anion influence during the catalyst optimization including an industrial perspective. The study shows a dominance of the counter anion, a dominance which up to now has been neglected in most of the routine screenings. In addn., a drastic substrate-dependency became obvious, even a marginal variation of the substrate already could strongly effect the catalytic activity and change the optimal counter anion or ligand. Based on the collected data a strategic concept for an efficient screening for a specific substrate is introduced, this concept can serve as an important guideline for catalyst optimization in homogeneous gold catalysis.
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11. 11
  (a) Neel, A. J.; Hilton, M. J.; Sigman, M. S.; Toste, F. D. Exploiting Non-covalent π Interactions for Catalyst Design. Nature 2017, 543, 637– 646, DOI: 10.1038/nature21701
  11a
  Exploiting non-covalent π interactions for catalyst design
  Neel, Andrew J.; Hilton, Margaret J.; Sigman, Matthew S.; Toste, F. Dean
  Nature (London, United Kingdom) (2017), 543 (7647), 637-646CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)
  A review. Mol. recognition, binding, and catalysis are often mediated by non-covalent interactions involving arom. functional groups. Although the relative complexity of these so-called π interactions has made them challenging to study, theory and modeling have now reached the stage at which we can explain their phys. origins and obtain reliable insight into their effects on mol. binding and chem. transformations. This offers opportunities for the rational manipulation of these complex non-covalent interactions and their direct incorporation into the design of small-mol. catalysts and enzymes.
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  (b) Fanourakis, A.; Docherty, P. J.; Chuentragool, P.; Phipps, R. J. Recent Developments in Enantioselective Transition Metal Catalysis Featuring Attractive Noncovalent Interactions between Ligand and Substrate. ACS Catal. 2020, 10, 10672– 10714, DOI: 10.1021/acscatal.0c02957
  11b
  Recent Developments in enantioselective transition metal catalysis featuring attractive non-covalent interactions between ligand and substrate
  Fanourakis, Alexander; Docherty, Philip J.; Chuentragool, Padon; Phipps, Robert J.
  ACS Catalysis (2020), 10 (18), 10672-10714CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
  A review. Enantioselective transition metal catalysis is an area very much at the forefront of contemporary synthetic research. The development of processes that enable the efficient synthesis of enantiopure compds. is of unquestionable importance to chemists working within the many diverse fields of the central science. Traditional approaches to solving this challenge have typically relied on leveraging repulsive steric interactions between chiral ligands and substrates in order to raise the energy of one of the diastereomeric transition states over the other. By contrast, this review examines an alternative tactic in which a set of attractive non-covalent interactions operating between transition metal ligands and substrates are used to control enantioselectivity. Examples where this creative approach has been successfully applied to render fundamental synthetic processes enantioselective are presented and discussed. In many of the cases examd., the ligand scaffold has been carefully designed to accommodate these attractive interactions while in others, the importance of the crit. interactions was only elucidated in subsequent computational and mechanistic studies. Through an exploration and discussion of several recent reports encompassing a wide range of reaction classes authors hope to inspire synthetic chemists to continue to develop asym. transformations based on this powerful concept.
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12. 12
  (a) Duarte, F.; Paton, R. S. Molecular Recognition in Asymmetric Counteranion Catalysis: Understanding Chiral Phosphate-Mediated Desymmetrization. J. Am. Chem. Soc. 2017, 139, 8886– 8896, DOI: 10.1021/jacs.7b02468
  12a
  Molecular Recognition in Asymmetric Counteranion Catalysis: Understanding Chiral Phosphate-Mediated Desymmetrization
  Duarte, Fernanda; Paton, Robert S.
  Journal of the American Chemical Society (2017), 139 (26), 8886-8896CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  We describe the first theor. study of a landmark example of chiral anion phase-transfer catalysis: the enantioselective ring-opening of meso-aziridinium and episulfonium cations promoted by asym. counteranion-directed catalysis (ACDC). The mechanism of ion-pairing, ring-opening, and catalyst deactivation have been studied in the condensed phase with both classical and quantum methods using explicitly and implicitly solvated models. We find that the stability of chiral ion-pairs, a prerequisite for asym. catalysis, is dominated by electrostatic interactions at long range and by CH···O interactions at short range. The decisive role of solvent upon ion-pair formation and of nonbonding interactions upon enantioselectivity are quantified by complementary computational approaches. The major enantiomer is favored by a smaller distortion of the substrate, demonstrated by a distortion/interaction anal. Our computational results rationalize the stereoselectivity for several exptl. results and demonstrate a combined classical/quantum approach to perform realistic modeling of chiral counterion catalysis in soln.
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  (b) Orlandi, M.; Coelho, J. A. S.; Hilton, M. J.; Toste, F. D.; Sigman, M. S. Parametrization of Non-covalent Interactions for Transition State Interrogation Applied to Asymmetric Catalysis. J. Am. Chem. Soc. 2017, 139, 6803– 6806, DOI: 10.1021/jacs.7b02311
  12b
  Parametrization of Non-covalent Interactions for Transition State Interrogation Applied to Asymmetric Catalysis
  Orlandi, Manuel; Coelho, Jaime A. S.; Hilton, Margaret J.; Toste, F. Dean; Sigman, Matthew S.
  Journal of the American Chemical Society (2017), 139 (20), 6803-6806CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The use of computed interaction energies and distances as parameters in multivariate correlations is introduced for postulating non-covalent interactions. This new class of descriptors affords multivariate correlations for two diverse catalytic systems with unique non-covalent interactions at the heart of each process. The presented methodol. is validated by directly connecting the non-covalent interactions defined through empirical data set analyses to the computationally derived transition states.
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  (c) Shoja, A.; Reid, J. P. Computational Insights into Privileged Stereocontrolling Interactions Involving Chiral Phosphates and Iminium Intermediates. J. Am. Chem. Soc. 2021, 143, 7209– 7215, DOI: 10.1021/jacs.1c03829
  12c
  Computational Insights into Privileged Stereocontrolling Interactions Involving Chiral Phosphates and Iminium Intermediates
  Shoja, Ali; Reid, Jolene P.
  Journal of the American Chemical Society (2021), 143 (18), 7209-7215CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The precise design of a catalyst for a given reaction is extremely difficult, often requiring a significant empirical screening campaign to afford products in high yields and enantiomeric excess. Design becomes even more challenging if one requires a catalyst that performs well for a diverse range of substrates. Such "privileged" catalysts exist, but little is known why they operate so generally. We report the results of computations which show that when substrate and catalyst features are conserved between significantly different mechanistic regimes, similar modes of activation can be invoked. As a validating case study, we explored a Hantzsch ester hydrogenation of α,β-unsatd. iminiums involving BINOL-derived chiral phosphates and find they impart asym. induction in an analogous fashion to their acid counterpart. Specifically, DFT calcns. at the IEFPCM(1,4-dioxane)-B3LYP/6-311+G(d,p)//B3LYP/6-31G(d) level predicted enantioselectivity to be close to the exptl. value (82% ee calcd., 96% ee exptl.) and showed that the reaction proceeds via a transition state involving two hydrogen-bonding interactions from the iminium intermediate and nucleophile to the catalyst. These interactions lower the energy of the transition structure and provide extra rigidity to the system. This new model invokes "privileged" noncovalent interactions and leads to a new explanation for the enantioselectivity outcome, ultimately providing the basis for the development of general catalyst design principles and the translation of mechanistically disparate reaction profiles for the prediction of enantioselectivity outcomes using statistical models.
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13. 13
  Zhang, Z.; Smal, V.; Retailleau, P.; Voituriez, A.; Frison, G.; Marinetti, A.; Guinchard, X. Tethered Counterion-Directed Catalysis: Merging the Chiral Ion-Pairing and Bifunctional Ligand Strategies in Enantioselective Gold(I) Catalysis. J. Am. Chem. Soc. 2020, 142, 3797– 3805, DOI: 10.1021/jacs.9b11154
  13
  Tethered Counterion-Directed Catalysis: Merging the Chiral Ion-pairing and Bifunctional Ligand Strategies in Enantioselective Gold(I) Catalysis
  Zhang, Zhenhao; Smal, Vitalii; Retailleau, Pascal; Voituriez, Arnaud; Frison, Gilles; Marinetti, Angela; Guinchard, Xavier
  Journal of the American Chemical Society (2020), 142 (8), 3797-3805CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Tethering a metal complex to its phosphate counterion via a phosphine ligand enables a new strategy in asym. counter anion-directed catalysis (ACDC). A straightforward, scalable synthetic route gives access to the gold(I) complex I of a chiral phosphine displaying a phosphoric acid function. The complex generates a catalytically active species with an unprecedented intramol. relationship between the cationic Au(I) center and the phosphate counterion. The benefits of tethering the two functions of the catalyst is demonstrated here in a tandem cycloisomerization/nucleophilic addn. reaction, by attaining high enantioselectivity levels (up to 97% ee) at a remarkable low 0.2 mol% catalyst loading. Remarkably the method is also compatible with a silver-free protocol.
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14. 14
  Michelet, V. Noble Metal-Catalyzed Enyne Cycloisomerizations and Related Reactions. Comprehensive Organic Synthesis, 2nd ed.; Elsevier, 2014; Vol. 5, pp 1483– 1536.
  There is no corresponding record for this reference.
15. 15
  For recent reviews on asymmetric gold catalysis, see the following:
  (a) Zi, W.; Toste, F. D. Recent Advances in Enantioselective Gold Catalysis. Chem. Soc. Rev. 2016, 45, 4567– 4589, DOI: 10.1039/C5CS00929D
  15a
  Recent advances in enantioselective gold catalysis
  Zi, Weiwei; Dean Toste, F.
  Chemical Society Reviews (2016), 45 (16), 4567-4589CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  Interest in homogeneous gold catalysis has undergone a marked increase. As strong yet air- and moisture-tolerant π-acids, cationic gold(I) complexes have been shown to catalyze diverse transformations of alkenes, alkynes and allenes, opening new opportunities for chem. synthesis. The development of efficient asym. variants is required in order to take full advantage of the preparative potential of these transformations. During the last few years, the chem. community has achieved tremendous success in the area. This review highlights the updated progress (2011-2015) in enantioselective gold catalysis. The discussion is classified according to the π-bonds activated by gold(I), in an order of alkynes, allenes and alkenes. Other gold activation modes, such as σ-Lewis acid catalyzed reactions and transformations of diazo compds. are also discussed.
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  (b) Li, Y.; Li, W.; Zhang, J. Gold-Catalyzed Enantioselective Annulations. Chem.─Eur. J. 2017, 23, 467– 512, DOI: 10.1002/chem.201602822
  15b
  Gold-Catalyzed Enantioselective Annulations
  Li, Yangyan; Li, Wenbo; Zhang, Junliang
  Chemistry - A European Journal (2017), 23 (3), 467-512CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. This review summarized the methods to construct chiral cyclic compds. by gold-catalyzed enantioselective annulations reported since 2005. The review was organized according to the general annulation types catalyzed by chiral gold complexes or chiral gold salts, which have four main types (cycloaddns., cyclizations of C-C multiple bonds with tethered nucleophiles, cycloisomerization or cyclization of enynes, and tandem annulations), as well as some other strategies. The general reaction mechanisms of each subcategory, key intermediates for some unusual transformations, and the application of several novel ligands and chiral goldsalts were also discussed.
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  (c) Jiang, J.-J.; Wong, M.-K. Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis. Chem.─Asian J. 2021, 16, 364– 377, DOI: 10.1002/asia.202001375
  15c
  Recent Advances in the Development of Chiral Gold Complexes for Catalytic Asymmetric Catalysis
  Jiang, Jia-Jun; Wong, Man-Kin
  Chemistry - An Asian Journal (2021), 16 (5), 364-377CODEN: CAAJBI; ISSN:1861-4728. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. This review summarizes newly developed gold-catalyzed enantioselective org. transformations and recent progress in ligand design (since 2016), organized according to different types of chiral ligands, including bisphosphine ligands, monophosphine ligands, phosphite-derived ligands, and N-heterocyclic carbene ligands for asym. gold(I) catalysis as well as heterocyclic carbene ligands and oxazoline ligands for asym. gold(III) catalysis.
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  (d) Porcel García, S. Gold Catalyzed Asymmetric Transformations. IntechOpen, 2021; DOI: 10.5772/intechopen.97519 .
  There is no corresponding record for this reference.
  (e) Reference (7b).
  There is no corresponding record for this reference.
16. 16
  (a) Cheng, X.; Zhang, L. Designed Bifunctional Ligands in Cooperative Homogeneous Gold Catalysis. CCS Chem. 2021, 3, 1989– 2002, DOI: 10.31635/ccschem.020.202000454
  16a
  Designed bifunctional ligands in cooperative homogeneous gold catalysis
  Cheng, Xinpeng; Zhang, Liming
  CCS Chemistry (2021), 3 (1), 1989-2002CODEN: CCCHB2 ISSN:. (Chinese Chemical Society)
  Over the past two decades, homogeneous gold catalysis has experienced exponential development and contributed a plethora of highly valuable synthetic methods to the synthetic toolbox. Metalligand cooperative catalysis is a versatile strategy for achieving highly efficient and/or novel catalysis but has seldom been explored in gold chem. This minireview summarizes the progress we have made in developing remotely functionalized biaryl-2-ylphosphine ligands and employing them in cooperative gold catalysis that achieves excellent catalytic efficiency or realizes previously unknown reactivities. This approach also provides new venues for implementing asym. gold catalysis.
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  (b) Zuccarello, G.; Zanini, M.; Echavarren, A. M. Buchwald-Type Ligands on Gold(I) Catalysis. Isr. J. Chem. 2020, 60, 360– 372, DOI: 10.1002/ijch.201900179
  16b
  Buchwald-Type Ligands on Gold(I) Catalysis
  Zuccarello, Giuseppe; Zanini, Margherita; Echavarren, Antonio M.
  Israel Journal of Chemistry (2020), 60 (3-4), 360-372CODEN: ISJCAT; ISSN:0021-2148. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. This review emphasizes how this privileged ligand class, as well as recent modifications on the biarylphosphine motive, have triggered the discovery of new reactivities in our research program. Finally, the introduction of chiral information on the ligand scaffold provides new solns. to the challenging gold(I)-catalyzed enantioselective transformations.
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17. 17
  (a) Schreiner, P. R. Metal-Free Organocatalysis through Explicit Hydrogen Bonding Interactions. Chem. Soc. Rev. 2003, 32, 289– 296, DOI: 10.1039/b107298f
  17a
  Metal-free organocatalysis through explicit hydrogen bonding interactions
  Schreiner, Peter R.
  Chemical Society Reviews (2003), 32 (5), 289-296CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. The metal (ion)-free catalysis of org. reactions is a contemporary challenge that is just being taken up by chemists. Hence, this field is in its infancy and is briefly reviewed here, along with some rough guidelines and concepts for further catalyst development. Catalysis through explicit hydrogen bonding interactions offers attractive alternatives to metal (ion)-catalyzed reactions by combining supramol. recognition with chem. transformations in an environmentally benign fashion. Although the catalytic rate accelerations relative to uncatalyzed reactions are often considerably less than for the metal (ion)-catalyzed variants, this need not be a disadvantage. Also, owing to weaker enthalpic binding interactions, product inhibition is rarely a problem and hydrogen bond additives are truly catalytic, even in water. A review.
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  (b) Doyle, A. G.; Jacobsen, E. N. Small-Molecule H-Bond Donors in Asymmetric Catalysis. Chem. Rev. 2007, 107, 5713– 5743, DOI: 10.1021/cr068373r
  17b
  Small-Molecule H-Bond Donors in Asymmetric Catalysis
  Doyle, Abigail G.; Jacobsen, Eric N.
  Chemical Reviews (Washington, DC, United States) (2007), 107 (12), 5713-5743CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review of asym. synthesis using small-mol. chiral hydrogen-bond donor catalysts in enantioselective addn. reactions to carbonyl, nitroalkene, α,β-unsatd. carbonyl, imine, and iminium ion electrophiles.
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18. 18
  For the only previous examples of phosphino(thio)urea Au(I) complexes, see the following:
  (a) Campbell, M. J.; Toste, F. D. Enantioselective Synthesis of Cyclic Carbamimidates via a Three-Component Reaction of Imines, Terminal Alkynes, and p-Toluenesulfonylisocyanate Using a Monophosphine Gold(I) Catalyst. Chem. Sci. 2011, 2, 1369– 1378, DOI: 10.1039/c1sc00160d
  18a
  Enantioselective synthesis of cyclic carbamimidates via a three-component reaction of imines, terminal alkynes, and p-toluenesulfonylisocyanate using a monophosphine gold(i) catalyst
  Campbell, Matthew J.; Toste, F. Dean
  Chemical Science (2011), 2 (7), 1369-1378CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
  A racemic gold(I)-catalyzed three-component reaction was developed to prep. cyclic carbamimidates from imines, terminal alkynes and sulfonyl isocyanates. This reaction exploits the carbophilic π-acidity of gold catalysts to first activate an alkyne toward deprotonation and secondly, to activate the internal alkyne generated toward intramol. O-cyclization. Unlike similar previously reported multicomponent gold-catalyzed reactions, the stereocenter generated during the alkynylation is preserved in the product. This trait was exploited by developing an enantioselective variant, using an unusual trans-1-diphenylphosphino-2-arylsulfamidocyclohexane ligand, moderate to excellent levels of enantioselectivity were obtained using a variety of N-(aryl)benzylidene aniline derivs. and the synthesis of the target compds. was achieved in 41-95% enantiomeric excess (18 examples).
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  (b) Franchino, A.; Martí, À.; Nejrotti, S.; Echavarren, A. M. Silver-Free Au(I) Catalysis Enabled by Bifunctional Urea- and Squaramide-Phosphine Ligands via H-Bonding. Chem.─Eur. J. 2021, 27, 11989– 11996, DOI: 10.1002/chem.202101751
  18b
  Silver-Free Au(I) Catalysis Enabled by Bifunctional Urea- and Squaramide-Phosphine Ligands via H-Bonding
  Franchino, Allegra; Marti, Alex; Nejrotti, Stefano; Echavarren, Antonio M.
  Chemistry - A European Journal (2021), 27 (46), 11989-11996CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A library of gold(I) chloride complexes I and II [R = H, CF3; Ar = Ph, 3,5-(CF3)2C6H3; X = CH2, (CH2)2, (CH2)3; Y = O, S] with phosphine ligands incorporating pendant (thio)urea and squaramide H-bond donors was prepd. with the aim of promoting chloride abstraction from Au(I) via H-bonding. In the absence of silver additives, complexes bearing squaramides and trifluoromethylated arom. ureas displayed good catalytic activity in the cyclization of N-propargyl benzamides, as well as in a 1,6-enyne cycloisomerization, a tandem cyclization-indole addn. reaction and the hydrohydrazination of phenylacetylene. Kinetic studies and DFT calcns. indicate that the energetic span of the reaction is accounted by both the chloride abstraction step, facilitated by the bidentate H-bond donor via an associative mechanism, and the subsequent cyclization step.
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19. 19
  (a) Akiyama, T. Stronger Brønsted Acids. Chem. Rev. 2007, 107, 5744– 5758, DOI: 10.1021/cr068374j
  19a
  Stronger Bronsted Acids
  Akiyama, Takahiko
  Chemical Reviews (Washington, DC, United States) (2007), 107 (12), 5744-5758CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. The application of Bronsted acids as catalysts in various reactions is discussed in detail.
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  (b) Terada, M. Binaphthol-derived Phosphoric Acid as a Versatile Catalyst for Enantioselective Carbon-Carbon Bond Forming Reactions. Chem. Commun. 2008, 4097– 4112, DOI: 10.1039/b807577h
  19b
  Binaphthol-derived phosphoric acid as a versatile catalyst for enantioselective carbon-carbon bond forming reactions
  Terada, Masahiro
  Chemical Communications (Cambridge, United Kingdom) (2008), (35), 4097-4112CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  A review. Binaphthol-derived monophosphoric acids have been designed as novel chiral Bronsted-acid catalysts. The chiral phosphoric acids thus developed function as efficient enantioselective catalysts for a variety of org. transformations, esp. for carbon-carbon bond forming reactions.
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  (c) Akiyama, T.; Mori, K. Stronger Brønsted Acids: Recent Progress. Chem. Rev. 2015, 115, 9277– 9306, DOI: 10.1021/acs.chemrev.5b00041
  19c
  Stronger Bronsted Acids: Recent Progress
  Akiyama, Takahiko; Mori, Keiji
  Chemical Reviews (Washington, DC, United States) (2015), 115 (17), 9277-9306CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. The synthetic utility of Bronsted acid as a catalyst for the C-C bond formation reaction has seen significant growth in the 21st century, and a range of stronger Bronsted-acid-catalyzed reactions have been developed. Strong Bronsted acids, such as TfOH and Tf2NH, efficiently activated carbonyl groups, alkenes, alkynes, in addn. to hydroxy groups. They sometimes functioned complementarily to Lewis-acid catalysts. Chiral Bronsted acid has become one of the most attractive subjects in organocatalysis in the past decade because of the versatility for a wide range of reactions. In addn. to the chiral phosphoric acids, chiral dicarboxylic acids, chiral disulfonic acids, and chiral sulfonimides have emerged as stronger Bronsted acids, and their synthetic utility has gained wide acceptance.
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  (d) Parmar, D.; Sugiono, E.; Raja, S.; Rueping, M. Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates. Chem. Rev. 2014, 114, 9047– 9153, DOI: 10.1021/cr5001496
  19d
  Complete Field Guide to Asymmetric BINOL-Phosphate Derived Bronsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Bronsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates
  Parmar, Dixit; Sugiono, Erli; Raja, Sadiya; Rueping, Magnus
  Chemical Reviews (Washington, DC, United States) (2014), 114 (18), 9047-9153CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. Chiral BINOL-derived Broensted acids have shown themselves to be highly efficient catalysts for a huge plethora of transformations and allow the end user to form C-C, C-H, and a variety of C-X bonds in a highly enantioselective fashion. Although within this category phosphoric acids are strongly known for activating imine substrates, stronger acids in the form of N-triflyl phosphoramides have bridged the gap somewhat to accessing previously thought out-of-reach substrates. Their utility in synthesis however is not solely limited to their acidic character, and more recently they have become extremely powerful chiral counterions for an increasing list of reactions. Furthermore, they can be combined with metal catalysts to create a synergistic effect, which has opened new reaction modes previously not possible with the individual catalysts themselves. Improved understanding of the mechanisms and interactions assocd. between the catalyst and the substrates has allowed research groups to develop highly powerful methodologies. Unfortunately, our understanding is still far from complete, and currently we have a crude understanding of how the catalysts function, but detailed exptl. and computational studies are still required for further progress in the field.
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  Correction:Parmar, D.; Sugiono, E.; Raja, S.; Rueping, M. Chem. Rev. 2017, 117, 10608– 10620, DOI: 10.1021/acs.chemrev.7b00197
  19
  Addition and Correction to Complete Field Guide to Asymmetric BINOL-Phosphate Derived Bronsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Bronsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates [Erratum to document cited in CA161:504781]
  Parmar, Dixit; Sugiono, Erli; Raja, Sadiya; Rueping, Magnus
  Chemical Reviews (Washington, DC, United States) (2017), 117 (15), 10608-10620CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review.
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20. 20
  Wang, Y.; Wang, Z.; Li, Y.; Wu, G.; Cao, Z.; Zhang, L. A General Ligand Design for Gold Catalysis Allowing Ligand-Directed anti-Nucleophilic Attack of Alkynes. Nat. Commun. 2014, 5, 3470, DOI: 10.1038/ncomms4470
  20
  A general ligand design for gold catalysis allowing ligand-directed anti-nucleophilic attack of alkynes
  Wang Yanzhao; Wang Zhixun; Wu Gongde; Cao Zheng; Zhang Liming; Li Yuxue
  Nature communications (2014), 5 (), 3470 ISSN:.
  Most homogenous gold catalyses demand ≥ 0.5 mol% catalyst loading. Owing to the high cost of gold, these reactions are unlikely to be applicable in medium- or large-scale applications. Here we disclose a novel ligand design based on the privileged (1,1'-biphenyl)-2-ylphosphine framework that offers a potentially general approach to dramatically lowering catalyst loading. In this design, an amide group at the 3'-position of the ligand framework directs and promotes nucleophilic attack at the ligand gold complex-activated alkyne, which is unprecedented in homogenous gold catalysis considering the spatial challenge of using ligand to reach anti-approaching nucleophile in a linear P-Au-alkyne centroid structure. With such a ligand, the gold(I) complex becomes highly efficient in catalysing acid addition to alkynes, with a turnover number up to 99,000. Density functional theory calculations support the role of the amide moiety in directing the attack of carboxylic acid via hydrogen bonding.
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21. 21
  (a) Zhang, Z.; Schreiner, P. R. (Thio)urea Organocatalysis─What Can Be Learnt from Anion Recognition?. Chem. Soc. Rev. 2009, 38, 1187– 1198, DOI: 10.1039/b801793j
  21a
  (Thio)urea organocatalysis - What can be learnt from anion recognition?
  Zhang, Zhiguo; Schreiner, Peter R.
  Chemical Society Reviews (2009), 38 (4), 1187-1198CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. The present crit. review outlines the close relationship and mutual interplay between mol. recognition, active site considerations in enzyme catalysis involving anions, and organocatalysis utilizing explicit hydrogen bonding. These interconnections are generally not made although, as we demonstrate, they are quite apparent as exemplified with pertinent examples in the field of (thio)urea organocatalysis. Indeed, the concepts of anion binding or binding with neg. (partially) charged heteroatoms is key for designing new organocatalytic transformations. Utilizing anions through recognition with hydrogen-bonding organocatalysts is still in its infancy but bears great potential. In turn, the discovery and mechanistic elucidation of such reactions is likely to improve the understanding of enzyme active sites (108 refs.).
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  (b) Amendola, V.; Fabbrizzi, L.; Mosca, L. Anion Recognition by Hydrogen Bonding: Urea-Based Receptors. Chem. Soc. Rev. 2010, 39, 3889– 3915, DOI: 10.1039/b822552b
  21b
  Anion recognition by hydrogen bonding: Urea-based receptors
  Amendola, Valeria; Fabbrizzi, Luigi; Mosca, Lorenzo
  Chemical Society Reviews (2010), 39 (10), 3889-3915CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. Since 1992 a variety of urea-based anion receptors were synthesized, of varying complexity and sophistication. This crit. review will focus on some distinctive aspects of anion recognition by urea derivs., with a special ref. to: (i) design and synthesis, (ii) methodologies for the investigation of the receptor-anion interaction in soln., (iii) the interpretation of the soln. behavior on the basis of the structural interplay between the receptor and the anion. The efficiency of urea as a receptor subunit depends on the presence of two proximate polarized N-H fragments, capable (i) of chelating a spherical anion or (ii) of donating two parallel H-bonds to the oxygen atoms of a carboxylate or of an inorg. oxoanion, a property which is shared with other diamides, e.g. squaramide. The wide use of urea in the design of neutral anion receptors seems to depends on the ease of its synthesis, in particular through the reaction of a primary amine group with an isocyanate, which allows the high-yield prepn. of sym. and unsym. substituted derivs. (83 refs.).
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  (c) Bregović, V. B.; Basarić, N.; Mlinarić-Majerski, K. Anion Binding with Urea and Thiourea Derivatives. Coord. Chem. Rev. 2015, 295, 80– 124, DOI: 10.1016/j.ccr.2015.03.011
  There is no corresponding record for this reference.
22. 22
  For reviews on supramolecular ligands for asymmetric metal catalysis, see the following:
  (a) Meeuwissen, J.; Reek, J. N. H. Supramolecular Catalysis Beyond Enzyme Mimics. Nat. Chem. 2010, 2, 615– 621, DOI: 10.1038/nchem.744
  22a
  Supramolecular catalysis beyond enzyme mimics
  Meeuwissen, Jurjen; Reek, Joost N. H.
  Nature Chemistry (2010), 2 (8), 615-621CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
  A review; supramol. catalysis - the assembly of catalyst species by harnessing multiple weak intramol. interactions - has, until recently, been dominated by enzyme-inspired approaches. Such approaches often attempt to create an enzyme-like 'active site' and have concd. on reactions similar to those catalyzed by enzymes themselves. Here, we discuss the application of supramol. assembly to the more traditional transition metal catalysis and to small-mol. organocatalysis. The modularity of self-assembled multicomponent catalysts means that a relatively small pool of catalyst components can provide rapid access to a large no. of catalysts that can be evaluated for industrially relevant reactions. In addn., we discuss how catalyst-substrate interactions can be tailored to direct substrates along particular reaction paths and selectivities.
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  (b) Carboni, S.; Gennari, C.; Pignataro, L.; Piarulli, U. Supramolecular Ligand-Ligand and Ligand-Substrate Interactions for Highly Selective Transition Metal Catalysis. Dalton Trans. 2011, 40, 4355– 4373, DOI: 10.1039/c0dt01517b
  22b
  Supramolecular ligand-ligand and ligand-substrate interactions for highly selective transition metal catalysis
  Carboni, Stefano; Gennari, Cesare; Pignataro, Luca; Piarulli, Umberto
  Dalton Transactions (2011), 40 (17), 4355-4373CODEN: DTARAF; ISSN:1477-9226. (Royal Society of Chemistry)
  A review. The use of non covalent supramol. ligand-ligand and ligand-substrate interactions in transition metal-catalyzed transformations is a new, rapidly emerging area of research. Noncovalent interactions between monodentate ligands such as hydrogen bonding, coordinative bonding, ion pairing, π-π interactions and the formation of inclusion compds., impart higher activity and chemo-, regio-, and stereoselectivity to the corresponding transition metal complexes in a no. of catalytic applications. Analogously, supramol. ligand-substrate interactions, and particularly hydrogen bonding, were used to direct the regio- and stereochem. of several metal-catalyzed reactions. The catalytic systems relying on supramol. interactions are generally capable of self-assembling from simpler components in the environment where catalysis is to take place, and are therefore very well-suited for combinatorial catalyst discovery strategies and high-throughput screening.
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  (c) Bellini, R.; van der Vlugt, J. I.; Reek, J. N. H. Supramolecular Self-Assembled Ligands in Asymmetric Transition Metal Catalysis. Isr. J. Chem. 2012, 52, 613– 629, DOI: 10.1002/ijch.201200002
  22c
  Supramolecular self-assembled ligands in asymmetric transition metal catalysis
  Bellini, Rosalba; van der Vlugt, Jarl Ivar; Reek, Joost N. H.
  Israel Journal of Chemistry (2012), 52 (7), 613-629CODEN: ISJCAT; ISSN:0021-2148. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review was given on the progress in asym. transition metal catalysis using supramol. self-assembled ligands. The design of novel chiral ligands is at the core of asym. catalysis. The catalytic characteristics of a transition metal catalyst such as activity, selectivity and stability can be fine-tuned by optimization of the steric and electronic properties of the coordinating ligands. In asym. transformations, catalyst optimization still relies to a large extent on trial-and-error and educated guesses. New strategies based on combinatorial screening and high-throughput experimentation have been introduced for the design and optimization of new ligands and catalytic systems. Supramol. bidentate ligands that form by self-assembly of building blocks are particularly suited for this combinatorial approach as the potential no. of catalysts grows exponentially with the no. of building blocks synthesized. Catalytic systems based on supramol. interactions have proven to be highly advantageous in creating large ligand libraries for high-throughput screening, which allows optimization of activity and selectivity for a variety of reactions.
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  (d) Raynal, M.; Ballester, P.; Vidal-Ferran, A.; van Leeuwen, P. W. N. M. Supramolecular Catalysis. Part 1: Non-Covalent Interactions as a Tool for Building and Modifying Homogeneous Catalysts. Chem. Soc. Rev. 2014, 43, 1660– 1733, DOI: 10.1039/C3CS60027K
  22d
  Supramolecular catalysis. Part 1: non-covalent interactions as a tool for building and modifying homogeneous catalysts
  Raynal, Matthieu; Ballester, Pablo; Vidal-Ferran, Anton; van Leeuwen, Piet W. N. M.
  Chemical Society Reviews (2014), 43 (5), 1660-1733CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review; supramol. catalysis is a rapidly expanding discipline which has benefited from the development of both homogeneous catalysis and supramol. chem. The properties of classical metal and org. catalysts can now be carefully tailored by means of several suitable approaches and the choice of reversible interactions such as hydrogen bond, metal-ligand, electrostatic and hydrophobic interactions. The first part of these two subsequent reviews will be dedicated to catalytic systems for which non-covalent interactions between the partners of the reaction have been designed although mimicking enzyme properties has not been intended. Ligand, metal, organocatalyst, substrate, additive, and metal counterion are reaction partners that can be held together by non-covalent interactions. The resulting catalysts possess unique properties compared to analogs lacking the assembling properties. Depending on the nature of the reaction partners involved in the interactions, distinct applications have been accomplished, mainly (i) the building of bidentate ligand libraries (intra ligand-ligand), (ii) the building of di- or oligonuclear complexes (inter ligand-ligand), (iii) the alteration of the coordination spheres of a metal catalyst (ligand-ligand additive), and (iv) the control of the substrate reactivity (catalyst-substrate). More complex systems that involve the cooperative action of three reaction partners have also been disclosed. In this review, special attention will be given to supramol. catalysts for which the obsd. catalytic activity and/or selectivity have been imputed to non-covalent interaction between the reaction partners. Addnl. features of these catalysts are the easy modulation of the catalytic performance by modifying one of their building blocks and the development of new catalytic pathways/reactions not achievable with classical covalent catalysts.
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  (e) Ohmatsu, K.; Ooi, T. Design of Supramolecular Chiral Ligands for Asymmetric Metal Catalysis. Tetrahedron Lett. 2015, 56, 2043– 2048, DOI: 10.1016/j.tetlet.2015.02.096
  22e
  Design of supramolecular chiral ligands for asymmetric metal catalysis
  Ohmatsu, Kohsuke; Ooi, Takashi
  Tetrahedron Letters (2015), 56 (16), 2043-2048CODEN: TELEAY; ISSN:0040-4039. (Elsevier Ltd.)
  A review. Three strategies for the development of supramol. chiral ligands for asym. metal catalysis are outlined. The basic ideas, advantages, and examples of each strategy are described.
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  (f) Trouvé, J.; Gramage-Doria, R. Beyond Hydrogen Bonding: Recent Trends of Outer Sphere Interactions in Transition Metal Catalysis. Chem. Soc. Rev. 2021, 50, 3565– 3584, DOI: 10.1039/D0CS01339K
  22f
  Beyond hydrogen bonding: recent trends of outer sphere interactions in transition metal catalysis
  Trouve, Jonathan; Gramage-Doria, Rafael
  Chemical Society Reviews (2021), 50 (5), 3565-3584CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)
  A review. Homogeneous catalytic reactions are typically controlled by the stereoelectronic nature of the ligand(s) that bind to the metal(s). The advantages of the so-called first coordination sphere effects have been used for the efficient synthesis of fine chems. relevant for industrial and academic labs. since more than half a century. Such level of catalyst control has significantly upgraded in the last few decades by mastering addnl. interactions beyond the first coordination sphere. These so-called second coordination sphere effects are mainly inspired by the action mode of nature's catalysts, enzymes, and, in general, rely on subtle hydrogen bonding for the exquisite control of activity and selectivity. In order to span the scope of this powerful strategy to challenges that cannot be solved purely by hydrogen bonding, a variety of less common interactions have been successfully introduced in the last few years for a fine chem. synthesis. This review covers the latest and most exciting developments of this newly flourishing area with a particular focus on highlighting how these types of interactions can be rationally implemented to control the reactivity in a remote fashion, which is far away from the active site similar to what enzymes also do.
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  For a seminal example involving ion-pairing interactions between an achiral ligand and a chiral anion, see the following:
  (g) Ohmatsu, K.; Ito, M.; Kunieda, T.; Ooi, T. Ion-Paired Chiral Ligands for Asymmetric Palladium Catalysis. Nat. Chem. 2012, 4, 473– 477, DOI: 10.1038/nchem.1311
  22g
  Ion-paired chiral ligands for asymmetric palladium catalysis
  Ohmatsu, Kohsuke; Ito, Mitsunori; Kunieda, Tomoatsu; Ooi, Takashi
  Nature Chemistry (2012), 4 (6), 473-477CODEN: NCAHBB; ISSN:1755-4330. (Nature Publishing Group)
  Conventional chiral ligands rely on the use of a covalently constructed, single chiral mol. embedded with coordinative functional groups. Here, the authors report a new strategy for the design of a chiral ligand for asym. transition-metal catalysis; approach is based on the development of an achiral cationic ammonium-phosphine hybrid ligand paired with a chiral binaphtholate anion. This ion-paired chiral ligand imparts a remarkable stereocontrolling ability to its palladium complex, which catalyzes a highly enantioselective allylic alkylation of α-nitro carboxylates. By exploiting the possible combinations of the achiral onium entities with suitable coordinative functionalities and readily available chiral acids, this approach should contribute to the development of a broad range of metal-catalyzed, stereoselective chem. transformations.
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23. 23
  Murata, M.; Buchwald, S. L. A General and Efficient Method for the Palladium-Catalyzed Cross-Coupling of Thiols and Secondary Phosphines. Tetrahedron 2004, 60, 7397– 7403, DOI: 10.1016/j.tet.2004.05.044
  23
  A general and efficient method for the palladium-catalyzed cross-coupling of thiols and secondary phosphines
  Murata, Miki; Buchwald, Stephen L.
  Tetrahedron (2004), 60 (34), 7397-7403CODEN: TETRAB; ISSN:0040-4020. (Elsevier B.V.)
  The general and efficient cross-coupling of thiols with aryl halides was developed utilizing Pd(OAc)2/1,1'-bis(diisopropylphosphino)ferrocene as the catalyst. The substrate scope was broad and included a variety of aryl bromides and chlorides, which can be coupled to aliph. and arom. thiols. The present catalyst system also enabled the palladium-catalyzed coupling of secondary phosphines with aryl bromides and chlorides.
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24. 24
  Luchini, G.; Ascough, D. M. H.; Alegre-Requena, J. V.; Gouverneur, V.; Paton, R. S. Data-Mining the Diaryl(thio)urea Conformational Landscape: Understanding the Contrasting Behavior of Ureas and Thioureas with Quantum Chemistry. Tetrahedron 2019, 75, 697– 702, DOI: 10.1016/j.tet.2018.12.033
  24
  Data-mining the diaryl(thio)urea conformational landscape and Understanding the contrasting behavior of ureas and thioureas with quantum chemistry
  Luchini, Guilian; Ascough, David M. H.; Alegre-Requena, Juan V.; Gouverneur, Veronique; Paton, Robert S.
  Tetrahedron (2019), 75 (6), 697-702CODEN: TETRAB; ISSN:0040-4020. (Elsevier Ltd.)
  The conformations adopted by urea and thiourea functional groups influence catalysis and binding. We combine data-mining with quantum chem. calcns. to understand the differences in conformational behavior for these two important structural motifs. We developed a Python tool to automate the compilation of X-ray structural information and perform conformational clustering and visualization, based on SMILES input. While diarylureas have an overwhelming preference for the anti,anti-conformer, diarylthioureas adopt a mixt. of anti,anti- and anti,syn-conformers. Computations show the anti,anti-thiourea conformer is destabilized by out-of-plane rotations which avoid a steric clash with the sulfur atom. These conformational preferences were studied computationally under a variety of conditions, and apart from in the gas-phase, a preference for anti,anti-ureas was found. Consistent with expts., this preference increases in more polar environments. Quant. predicted ratios are sensitive to the computational treatment of solvation effects, with COSMO-RS giving more realistic amts. of the anti,anti-conformer in THF and DMSO.
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25. 25
  Nakashima, D.; Yamamoto, H. Design of Chiral N-Triflyl Phosphoramide as a Strong Chiral Brønsted Acid and Its Application to Asymmetric Diels-Alder Reaction. J. Am. Chem. Soc. 2006, 128, 9626– 9627, DOI: 10.1021/ja062508t
  25
  Design of Chiral N-Triflyl Phosphoramide as a Strong Chiral Bronsted Acid and Its Application to Asymmetric Diels-Alder Reaction
  Nakashima, Daisuke; Yamamoto, Hisashi
  Journal of the American Chemical Society (2006), 128 (30), 9626-9627CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  A highly reactive and acidic chiral Bronsted acid catalyst, chiral BINOL N-triflyl phosphoramide, was developed. Highly enantioselective Diels-Alder reaction of α,β-unsatd. ketone with silyloxydiene was demonstrated using this chiral Bronsted acid catalyst.
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26. 26
  (a) Nieto-Oberhuber, C.; López, S.; Echavarren, A. M. Intramolecular [4 + 2] Cycloadditions of 1,3-Enynes or Arylalkynes with Alkenes with Highly Reactive Cationic Phosphine Au(I) Complexes. J. Am. Chem. Soc. 2005, 127, 6178– 6179, DOI: 10.1021/ja042257t
  26a
  Intramolecular [4+2] cycloadditions of 1,3-enynes or arylalkynes with alkenes with highly reactive cationic phosphine Au(I) complexes
  Nieto-Oberhuber, Cristina; Lopez, Salome; Echavarren, Antonio M.
  Journal of the American Chemical Society (2005), 127 (17), 6178-6179CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  New Au(I) complexes with bulky, biphenyl phosphines are the most reactive catalysts for the cyclizations of enynes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Nazarov-type ring expansion. 1,8-Dien-3-ynes also cyclize by a 5-exo-dig pathway to form hydrindanes. While thermal intramol. [4+2] cycloaddn. reactions (dehydro Diels-Alder reactions) of enynes with alkenes take place at high temps., the transformations reported here proceed with gold(I) catalysts and provide bicyclic or tricyclic ring systems.
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  (b) Nieto-Oberhuber, C.; Pérez-Galán, P.; Herrero-Gómez, E.; Lauterbach, T.; Rodríguez, C.; López, S.; Bour, C.; Rosellón, A.; Cárdenas, D. J.; Echavarren, A. M. Gold(I)-Catalyzed Intramolecular [4 + 2] Cycloadditions of Arylalkynes or 1,3-Enynes with Alkenes: Scope and Mechanism. J. Am. Chem. Soc. 2008, 130, 269– 279, DOI: 10.1021/ja075794x
  26b
  Gold(I)-Catalyzed Intramolecular [4+2] Cycloadditions of Arylalkynes or 1,3-Enynes with Alkenes: Scope and Mechanism
  Nieto-Oberhuber, Cristina; Perez-Galan, Patricia; Herrero-Gomez, Elena; Lauterbach, Thorsten; Rodriguez, Cristina; Lopez, Salome; Bour, Christophe; Rosellon, Antonio; Cardenas, Diego J.; Echavarren, Antonio M.
  Journal of the American Chemical Society (2008), 130 (1), 269-279CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  The cyclizations of enynes substituted at the alkyne gives products of formal [4+2] cyclization with Au(I) catalysts. 1,8-Dien-3-ynes cyclize by a 5-exo-dig pathway to form hydrindanes. 1,6-Enynes with an aryl ring at the alkyne give 2,3,9,9a-tetrahydro-1H-cyclopenta[b]naphthalenes by a 5-exo-dig cyclization followed by a Friedel-Crafts-type ring expansion. A 6-endo-dig cyclization is also obsd. in some cases as a minor process, although in a few cases, this is the major cyclization pathway. In addn. to cationic gold complexes bearing bulky biphenyl phosphines, a gold complex with tris(2,6-di-tert-butylphenyl)phosphite is exceptionally reactive as a catalyst for this reaction. This cyclization can also be carried out very efficiently with heating under microwave irradn. DFT calcns. support a stepwise mechanism for the cycloaddn. by the initial formation of an anti-cyclopropyl gold(I)-carbene, followed by its opening to form a carbocation stabilized by a π interaction with the aryl ring, which undergoes a Friedel-Crafts-type reaction.
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27. 27
  Previous asymmetric versions, all based on chiral ligands for Au(I), lack either scope or high enantiocontrol:
  (a) Two examples only (44–99% yield, 92–93% ee):Chao, C.-M.; Vitale, M. R.; Toullec, P. Y.; Genêt, J.-P.; Michelet, V. Asymmetric Gold-Catalyzed Hydroarylation/Cyclization Reactions. Chem.─Eur. J. 2009, 15, 1319– 1323, DOI: 10.1002/chem.200802341
  27a
  Asymmetric gold-catalyzed hydroarylation/cyclization reactions
  Chao, Chung-Meng; Vitale, Maxime R.; Toullec, Patrick Y.; Genet, Jean-Pierre; Michelet, Veronique
  Chemistry - A European Journal (2009), 15 (6), 1319-1323CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
  An efficient Au1 catalytic system is described for the enantioselective hydroarylation/cyclization reaction of 1,6-enynes. Use of the (R)-4-MeO-3,5-(tBu)2-MeOBIPHEP-gold complex led to clean rearrangements implying the formal addn. of a carbon nucleophile (1,3,5-trimethoxybenzene, 1,3- dimethoxybenzene, pyrrole, 1,3,5-trimethoxy-2-bromobenzene and indole derivs.) to an alkene followed by a cyclization process.
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  (b) One further example (86% yield, 16% ee):Pradal, A.; Chao, C.-M.; Vitale, M. R.; Toullec, P. Y.; Michelet, V. Asymmetric Au-Catalyzed Domino Cyclization/Nucleophile Addition Reactions of Enynes in the Presence of Water, Methanol and Electron-rich Aromatic Derivatives. Tetrahedron 2011, 67, 4371– 4377, DOI: 10.1016/j.tet.2011.03.071
  27b
  Asymmetric Au-catalyzed domino cyclization/nucleophile addition reactions of enynes in the presence of water, methanol and electron-rich aromatic derivatives
  Pradal, Alexandre; Chao, Chung-Meng; Vitale, Maxime R.; Toullec, Patrick Y.; Michelet, Veronique
  Tetrahedron (2011), 67 (24), 4371-4377CODEN: TETRAB; ISSN:0040-4020. (Elsevier Ltd.)
  An efficient Au(I) catalytic system is described for the asym. domino cyclization/functionalization reactions of functionalized 1,6-enynes in the presence of an external nucleophile. The use of (R)-4-MeO-3,5-(t-Bu)2-MeOBIPHEP ligand assocd. with gold led to clean rearrangements implying the formal addn. of an oxygen or carbon nucleophile to an alkene followed by a cyclization process. The enantiomeric excesses were highly dependent on the substrate/nucleophile combination. Very good enantiomeric excesses up to 98% were obtained in the case of substrates bearing larger groups (hindered diesters and disulfones) and in the case of hindered carbon nucleophiles.
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  (c) Five examples (70–95% yield, 73–88% ee):Delpont, N.; Escofet, I.; Pérez-Galán, P.; Spiegl, D.; Raducan, M.; Bour, C.; Sinisi, R.; Echavarren, A. M. Modular Chiral Gold(I) Phosphite Complexes. Catal. Sci. Technol. 2013, 3, 3007– 3012, DOI: 10.1039/c3cy00250k
  27c
  Modular chiral gold(I) phosphite complexes
  Delpont, Nicolas; Escofet, Imma; Perez-Galan, Patricia; Spiegl, Dirk; Raducan, Mihai; Bour, Christophe; Sinisi, Riccardo; Echavarren, Antonio M.
  Catalysis Science & Technology (2013), 3 (11), 3007-3012CODEN: CSTAGD; ISSN:2044-4753. (Royal Society of Chemistry)
  Chiral gold(I) phosphite complexes are readily prepd. modularly from 3,3'-bis(triphenylsilyl)-1,1'-bi-2-naphthol. These chiral gold(I) phosphite complexes are very reactive precatalysts for the [4+2] cycloaddn. of aryl-substituted 1,6-enynes with enantiomeric ratios ranging from 86:14 up to 94:6.
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  (d) One example only (99% yield, 91% ee):Aillard, P.; Dova, D.; Magné, V.; Retailleau, P.; Cauteruccio, S.; Licandro, E.; Voituriez, A.; Marinetti, A. The Synthesis of Substituted Phosphathiahelicenes via Regioselective Bromination of a Preformed Helical Scaffold: A New Approach to Modular Ligands for Enantioselective Gold-Catalysis. Chem. Commun. 2016, 52, 10984– 10987, DOI: 10.1039/C6CC04765C
  27d
  The synthesis of substituted phosphathiahelicenes via regioselective bromination of a preformed helical scaffold: a new approach to modular ligands for enantioselective gold-catalysis
  Aillard, Paul; Dova, Davide; Magne, Valentin; Retailleau, Pascal; Cauteruccio, Silvia; Licandro, Emanuela; Voituriez, Arnaud; Marinetti, Angela
  Chemical Communications (Cambridge, United Kingdom) (2016), 52 (73), 10984-10987CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  Substituted phosphathiahelicenes were prepd. via a straightforward two-step procedure involving the regioselective bromination of a preformed helical scaffold, followed by Pd-catalyzed coupling reactions with arylboronic acid or alkynes. The new helicenes were used as ligands in Au(I)-catalyzed [4+2] cyclizations of 1,6-enynes. The resulting dihydro-cyclopenta[b]naphthalene deriv. was obtained in excellent yields and with up to 91% ee.
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  (e) 17 examples (61–99% yield, 58–92% ee):Zuccarello, G.; Mayans, J. G.; Escofet, I.; Scharnagel, D.; Kirillova, M. S.; Pérez-Jimeno, A. H.; Calleja, P.; Boothe, J. R.; Echavarren, A. M. Enantioselective Folding of Enynes by Gold(I) Catalysts with a Remote C₂-Chiral Element. J. Am. Chem. Soc. 2019, 141, 11858– 11863, DOI: 10.1021/jacs.9b06326
  27e
  Enantioselective Folding of Enynes by Gold(I) Catalysts with a Remote C2-Chiral Element
  Zuccarello, Giuseppe; Mayans, Joan G.; Escofet, Imma; Scharnagel, Dagmar; Kirillova, Mariia S.; Perez-Jimeno, Alba H.; Calleja, Pilar; Boothe, Jordan R.; Echavarren, Antonio M.
  Journal of the American Chemical Society (2019), 141 (30), 11858-11863CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Chiral gold(I) catalysts have been designed based on a modified JohnPhos ligand with a distal C2-2,5-diarylpyrrolidine that creates a tight binding cavity. The C2-chiral element is close to where the C-C bond formation takes place in cyclizations of 1,6-enynes. These chiral mononuclear catalysts have been applied for the enantioselective 5-exo-dig and 6-endo-dig cyclization of different 1,6-enynes as well as in the first enantioselective total synthesis of three members of the carexane family of natural products. Opposite enantioselectivities have been achieved in seemingly analogous reactions of 1,6-enynes, which result from different chiral folding of the substrates based on attractive aryl-aryl interactions.
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  (f) One example only (92% yield, 94% ee):Magné, V.; Sanogo, Y.; Demmer, C. S.; Retailleau, P.; Marinetti, A.; Guinchard, X.; Voituriez, A. Chiral Phosphathiahelicenes: Improved Synthetic Approach and Uses in Enantioselective Gold(I)-Catalyzed [2 + 2] Cycloadditions of N-Homoallenyl Tryptamines. ACS Catal. 2020, 10, 8141– 8148, DOI: 10.1021/acscatal.0c01819
  27f
  Chiral Phosphathiahelicenes: Improved Synthetic Approach and Uses in Enantioselective Gold(I)-Catalyzed [2+2] Cycloadditions of N-Homoallenyl Tryptamines
  Magne, Valentin; Sanogo, Youssouf; Demmer, Charles S.; Retailleau, Pascal; Marinetti, Angela; Guinchard, Xavier; Voituriez, Arnaud
  ACS Catalysis (2020), 10 (15), 8141-8148CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)
  A chiral phosphathiahelicene scaffold displaying a phosphole and a thiophene unit as the terminal rings of the helical sequence I (7, M-isomer shown, Men = l-menthyl, R = H, X = O) has been synthesized and characterized by spectroscopic methods and X-ray diffraction studies. The phosphine oxides (HelPhos-V oxides) have been obtained following a robust and scalable synthetic approach, based on a nickel-promoted alkyne cyclotrimerization reaction. Then, late-stage functionalization has been carried out via a bromination/palladium coupling reaction sequence, giving phosphole P-oxides (9, 10; shown as I, X = O, R = Ph, C≡CPh). The HelPhos-V gold(I) complexes (11, shown as I, R = H, X = AuCl) have been used as catalysts in the unprecedented enantioselective [2+2] cyclization of N-homoallenyl tryptamine derivs., to afford indolenine-fused cyclobutanes II [Ns = 4-NO2C6H4SO2, R = Me, RR = (CH2)5; R1 = H, Me, Cl, MeO] in good isolated yields, with enantiomeric excesses up to 93%.
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28. 28
  N-Triflyl phosphoric amide D1 has a pK_a value 0.9 units lower than the corresponding phosphoric acid TRIP-H (4.2 vs 3.3, both values in DMSO at 25 °C):
  Christ, P.; Lindsay, A. G.; Vormittag, S. S.; Neudörfl, J.-M.; Berkessel, A.; O’Donoghue, A. C. pK_a Values of Chiral Brønsted Acid Catalysts: Phosphoric Acids/Amides, Sulfonyl/Sulfuryl Imides, and Perfluorinated TADDOLs (TEFDDOLs). Chem.─Eur. J. 2011, 17, 8524– 8528, DOI: 10.1002/chem.201101157
  28
  pKa Values of Chiral Bronsted Acid Catalysts: Phosphoric Acids/Amides, Sulfonyl/Sulfuryl Imides, and Perfluorinated TADDOLs (TEFDDOLs)
  Christ, Philipp; Lindsay, Anita G.; Vormittag, Sonja S.; Neudoerfl, Joerg-M.; Berkessel, Albrecht; O'Donoghue, AnnMarie C.
  Chemistry - A European Journal (2011), 17 (31), 8524-8528, S8524/1-S8524/58CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Quant. conversion of the Bronsted acid to the corresponding conjugate base in the presence of NaOH was recoreded using UV/Vis spectra with a const. concn. of indicator, 4-chloro-2,6-dinitrophenol (prepd.), 2,4-dinitrophenol, 2,4-dinitronaphthol, 4-nitrophenol, or phenol, in DMSO. Phosphoric acids stability was detd. via 1H NMR under conditions for pKa detn.
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29. 29
  Raubenheimer, H. G.; Schmidbaur, H. Gold Chemistry Guided by the Isolobality Concept. Organometallics 2012, 31, 2507– 2522, DOI: 10.1021/om2010113
  29
  Gold chemistry guided by the isolobality concept
  Raubenheimer, Helgard G.; Schmidbaur, Hubert
  Organometallics (2012), 31 (7), 2507-2522CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
  A review. Chem. of gold polynuclear compds. is considered from the point of view of isolobality concept. The general isolobality concept presented by Hoffmann, Stone, and Mingos in the early 1980s has had-tacitly or explicitly-a great impact on the development of many areas of inorg., organometallic, and coordination chem. Pertinent considerations were fruitful esp. in gold chem., because isolobal relations between gold(I) cations [Au]+ and their complexes [LAu]+ on the one hand and protons [H]+, various carbocations [R]+, and other simple species on the other are particularly obvious. Work guided by these relationships has included almost all fields of gold chem., from simple high-energy species in the gas phase to homoat. clusters of gold atoms or heteroat. aggregates with main-group and transition elements. Recent work has also concd. on the specific mechanisms of reactions catalyzed either by protons or by the above gold cations with a variety of new ligands L in sep. or tandem reaction sequences. The present review summarizes classical and current lines of research that have followed the original concept up to its present frontier version of "autogenic isolobality".
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30. 30
  Reid, J. P.; Goodman, J. M. Goldilocks Catalysts: Computational Insights into the Role of the 3,3′ Substituents on the Selectivity of BINOL-Derived Phosphoric Acid Catalysts. J. Am. Chem. Soc. 2016, 138, 7910– 7917, DOI: 10.1021/jacs.6b02825
  30
  Goldilocks Catalysts: Computational Insights into the Role of the 3,3' Substituents on the Selectivity of BINOL-Derived Phosphoric Acid Catalysts
  Reid, Jolene P.; Goodman, Jonathan M.
  Journal of the American Chemical Society (2016), 138 (25), 7910-7917CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  BINOL-derived phosphoric acids provide effective asym. catalysis for many org. reactions. Catalysts based on this scaffold show a large structural diversity, esp. in the 3,3' substituents, and little is known about the mol. requirements for high selectivity. As a result, selection of the best catalyst for a particular transformation requires a trial and error screening process, as the size of the 3,3' substituents is not simply related to their efficacy: the right choice is neither too large nor too small. We have developed an approach to identify and quantify structural features on the catalyst that det. selectivity. We show that the application of quant. steric parameters (a new measure, AREA(θ), and rotation barrier) to an imine hydrogenation reaction allows the identification of catalyst features necessary for efficient stereoinduction, validated by QM/MM hybrid calcns.
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31. 31
  (a) Kepp, K. P. A Quantitative Scale of Oxophilicity and Thiophilicity. Inorg. Chem. 2016, 55, 9461– 9470, DOI: 10.1021/acs.inorgchem.6b01702
  31a
  A Quantitative Scale of Oxophilicity and Thiophilicity
  Kepp, Kasper P.
  Inorganic Chemistry (2016), 55 (18), 9461-9470CODEN: INOCAJ; ISSN:0020-1669. (American Chemical Society)
  Oxophilicity and thiophilicity are widely used concepts with no quant. definition. In this paper, a simple, generic scale is developed that solves issues with ref. states and system dependencies and captures empirically known tendencies toward oxygen. This enables a detailed anal. of the fundamental causes of oxophilicity. Notably, the notion that oxophilicity relates to Lewis acid hardness is invalid. Rather, oxophilicity correlates only modestly and inversely with abs. hardness and more strongly with electronegativity and effective nuclear charge. Since oxygen is highly electroneg., ionic bonding is stronger to metals of low electronegativity. Left-side d-block elements with low effective nuclear charges and electronegativities are thus highly oxophilic, and the f-block elements, not because of their hardness, which is normal, but as a result of the small ionization energies of their outermost valence electrons, can easily transfer electrons to fulfill the electron demands of oxygen. Consistent with empirical experience, the most oxophilic elements are found in the left part of the d block, the lanthanides, and the actinides. The d-block elements differ substantially in oxophilicity, quantifying their different uses in a wide range of chem. reactions; thus, the use of mixed oxo- and thiophilic (i.e., "mesophilic") surfaces and catalysts as a design principle can explain the success of many recent applications. The proposed scale may therefore help to rationalize and improve chem. reactions more effectively than current qual. considerations of oxophilicity.
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  (b) Izaga, A.; Herrera, R. P.; Gimeno, M. C. Gold(I)-Mediated Thiourea Organocatalyst Activation: A Synergic Effect for Asymmetric Catalysis. ChemCatChem 2017, 9, 1313– 1321, DOI: 10.1002/cctc.201601527
  31b
  Gold(I)-Mediated Thiourea Organocatalyst Activation: A Synergic Effect for Asymmetric Catalysis
  Izaga, Anabel; Herrera, Raquel P.; Gimeno, M. Concepcion
  ChemCatChem (2017), 9 (7), 1313-1321CODEN: CHEMK3; ISSN:1867-3880. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Several group 11 metal complexes with chiral thiourea organocatalysts have been prepd. and tested as organocatalysts. The promising results on the influence of metal-assisted thiourea organocatalysts in the asym. Friedel-Crafts alkylation of indole with nitrostyrene are described. Better results with the metal complexes have been achieved because of the cooperative effects between the chiral thiourea and the metal. The synergic effect between both species is higher than the effect promoted by each one sep., esp. for gold(I). These outcomes are attributed to a pioneering gold(I) activation of the thiourea catalysts, affording a more acidic and rigid catalytic complex than that provided by the thiourea alone. Furthermore, the use of the gold-thiourea organocatalyst allows reducing the catalyst loading to 1-3 mol %. This contribution could become an important starting point for further investigations opening a new line of research overlooked so far in the literature.
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32. 32
  Reichardt, C. Solvatochromic Dyes as Solvent Polarity Indicators. Chem. Rev. 1994, 94, 2319– 2358, DOI: 10.1021/cr00032a005
  32
  Solvatochromic Dyes as Solvent Polarity Indicators
  Reichardt, Christian
  Chemical Reviews (Washington, DC, United States) (1994), 94 (8), 2319-58CODEN: CHREAY; ISSN:0009-2665.
  This review with 345 refs. compiles pos. and neg. solvatochromic compds. which have been used to establish empirical scales of solvent polarity by means of UV/visible/near-IR spectroscopic measurements in soln. with particular emphasis on the ET(30) scale derived from neg. solvatochromic pyridinium N-phenolate betaine dyes. A discussion is presented on the concept of solvent polarity and how empirical parameters of solvent polarity can be derived and understood in the framework of linear free-energy relationships.
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33. 33
  All gold complexes used so far for the enantioselective cyclization of O-tethered 1,6-enynes bear chiral ligands. For a complete overview, see the following:
  (a) Mato, M.; Franchino, A.; García-Morales, C.; Echavarren, A. M. Gold-Catalyzed Synthesis of Small Rings. Chem. Rev. 2021, 121, 8613– 8684, DOI: 10.1021/acs.chemrev.0c00697
  33a
  Gold-Catalyzed Synthesis of Small Rings
  Mato, Mauro; Franchino, Allegra; Garcia-Morales, Cristina; Echavarren, Antonio M.
  Chemical Reviews (Washington, DC, United States) (2021), 121 (14), 8613-8684CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)
  A review. This review aimed to provide a comprehensive summary of all the major advances and discoveries made in the gold-catalyzed synthesis of cyclopropanes, cyclopropenes, cyclobutanes, cyclobutenes, and their corresponding heterocyclic or heterosubstituted analogs.
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  For seminal examples, see the following:
  (b) Chao, C.-M.; Beltrami, D.; Toullec, P. Y.; Michelet, V. Asymmetric Au(I)-Catalyzed Synthesis of Bicyclo[4.1.0]heptene Derivatives via a Cycloisomerization Process of 1,6-Enynes. Chem. Commun. 2009, 6988– 6990, DOI: 10.1039/b913554e
  33b
  Asymmetric Au(I)-catalyzed synthesis of bicyclo[4.1.0]heptene derivatives via a cycloisomerization process of 1,6-enynes
  Chao, Chung-Meng; Beltrami, Denis; Toullec, Patrick Y.; Michelet, Veronique
  Chemical Communications (Cambridge, United Kingdom) (2009), (45), 6988-6990CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)
  The enantioselective asym. gold-catalyzed cycloisomerization reactions of heteroatom tethered 1,6-enynes are conducted in the presence of a chiral cationic Au(I) catalyst (I/AgOTf) in toluene under mild conditions. These transformations lead to functionalized aza- or oxabicyclo[4.1.0]heptene derivs., e.g., II, in excellent enantiomeric excesses ranging from 90-98%.
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  (c) Teller, H.; Corbet, M.; Mantilli, L.; Gopakumar, G.; Goddard, R.; Thiel, W.; Fürstner, A. One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone. J. Am. Chem. Soc. 2012, 134, 15331– 15342, DOI: 10.1021/ja303641p
  33c
  One-Point Binding Ligands for Asymmetric Gold Catalysis: Phosphoramidites with a TADDOL-Related but Acyclic Backbone
  Teller, Henrik; Corbet, Matthieu; Mantilli, Luca; Gopakumar, Gopinadhanpillai; Goddard, Richard; Thiel, Walter; Fuerstner, Alois
  Journal of the American Chemical Society (2012), 134 (37), 15331-15342CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Nonracemic gold complexes such as I (R = Ph, 4-Me3CC6H4) contg. monoligated phosphoramidites incorporating TADDOL-related diols with an acyclic backbone were enantioselective catalysts for a variety of transformations with good to outstanding enantioselectivities; the novel ligands incorporate an acyclic di-Me ether backbone instead of the (isopropylidene) acetal moiety characteristic for traditional TADDOL ligands. Gold TADDOL-related monocyclic phosphoramidite complexes were used as catalysts for diastereoselective and enantioselective reactions including the [2+2] and [4+2] cycloaddns. of eneallenes such as II [R1 = Ph, 4-MeOC6H4, 4-Me3COC6H4; X = (MeO2C)2C, (PhCH2O2C)2C, (Me3CO2C)2C, TsN, (PhSO2)2C] and dieneallenes to bicyclic bicycloheptanes such as III [R1 = Ph, 4-MeOC6H4, 4-Me3COC6H4; X = (MeO2C)2C, (PhCH2O2C)2C, (Me3CO2C)2C, TsN, (PhSO2)2C] and alkylidenehydrindanes, the cycloisomerizations of protected propargyl allyl amines and of allylic propargyl ethers to tetrahydrocyclopropapyridines and dihydrocyclopropapyrans, the hydroarylation of (allenylmethyl)arylcarbamates to give alkenylindolines, and the hydroamination and hydroalkoxylation reactions of pentadienylsulfonamides and a pentadienol to give alkenylpyrrolidines and an alkenyltetrahydrofuran. The practical use of gold TADDOL-related monocyclic phosphoramidite complexes is shown by an efficient synthesis of the antidepressive drug candidate (-)-GSK 1360707 IV•HCl using a gold complex-catalyzed cycloisomerization reaction as the key step. The structures of transition states and intermediates for the cycloisomerization of an (allyl)(bromophenylpropargyl)methanesulfonamide to enantiomeric tetrahydrocyclopropapyridines were detd. using d. functional theor. calcns. The structures of I (R = Ph, 4-Me3CC6H4), ent-I (R = 2-naphthyl), II (R1 = Ph; X = TsN), a tetrahydrocyclopropapyridine, a dioxatricycloundecene, a dihydropyranooxepine, and a dioxatetracycloundecane were detd. by X-ray crystallog.
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34. 34
  Sanjuán, A. M.; Martínez, A.; García-García, P.; Fernández-Rodríguez, M. A.; Sanz, R. Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes. Beilstein J. Org. Chem. 2013, 9, 2242– 2249, DOI: 10.3762/bjoc.9.263
  34
  Gold(I)-catalyzed 6-endo hydroxycyclization of 7-substituted-1,6-enynes
  Sanjuan, Ana M.; Martinez, Alberto; Garcia-Garcia, Patricia; Fernandez-Rodriguez, Manuel A.; Sanz, Roberto
  Beilstein Journal of Organic Chemistry (2013), 9 (), 2242-2249, 8 pp.CODEN: BJOCBH; ISSN:1860-5397. (Beilstein-Institut zur Foerderung der Chemischen Wissenschaften)
  The cyclization of o-(alkynyl)-3-(methylbut-2-enyl)benzenes, 1,6-enynes having a condensed arom. ring at C3-C4 positions, has been studied under the catalysis of cationic gold(I) complexes. The selective 6-endo-dig mode of cyclization obsd. for the 7-substituted substrates in the presence of water or methanol giving rise to hydroxy(methoxy)-functionalized dihydronaphthalene derivs. is highly remarkable in the context of the obsd. reaction pathways for the cycloisomerizations of 1,6-enynes bearing a trisubstituted olefin.
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35. 35
  See Supporting Information for discussion on other nucleophiles and reaction side products.
  There is no corresponding record for this reference.
36. 36
  (a) Pfeifer, L.; Engle, K. M.; Pidgeon, G. W.; Sparkes, H. A.; Thompson, A. L.; Brown, J. M.; Gouverneur, V. Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power. J. Am. Chem. Soc. 2016, 138, 13314– 13325, DOI: 10.1021/jacs.6b07501
  36a
  Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power
  Pfeifer, Lukas; Engle, Keary M.; Pidgeon, George W.; Sparkes, Hazel A.; Thompson, Amber L.; Brown, John M.; Gouverneur, Veronique
  Journal of the American Chemical Society (2016), 138 (40), 13314-13325CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5'-fluoro-5'-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F-. Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramol. chem. Herein we disclose a detailed study examg. the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in soln. phase and explore the reactivity of these complexes as a fluoride source in SN2 chem. Exptl. data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett anal. of aryl groups on the urea indicates that fluoride binding is dependent on σp and σm parameters with stronger binding being obsd. for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alc.-fluoride complexes, but SN2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate consts. at higher diln. support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF]- (U = urea) resulting from partial dissocn. of the parent compd. [U2F]-. The dissocn. processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in soln.
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  (b) Ibba, F.; Pupo, G.; Thompson, A. L.; Brown, J. M.; Claridge, T. D. W.; Gouverneur, V. Impact of Multiple Hydrogen Bonds with Fluoride on Catalysis: Insight from NMR Spectroscopy. J. Am. Chem. Soc. 2020, 142, 19731– 19744, DOI: 10.1021/jacs.0c09832
  36b
  Impact of Multiple Hydrogen Bonds with Fluoride on Catalysis: Insight from NMR Spectroscopy
  Ibba, Francesco; Pupo, Gabriele; Thompson, Amber L.; Brown, John M.; Claridge, Timothy D. W.; Gouverneur, Veronique
  Journal of the American Chemical Society (2020), 142 (46), 19731-19744CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Hydrogen-bonding interactions have been explored in catalysis, enabling complex chem. reactions. Recently, enantioselective nucleophilic fluorination with metal alkali fluoride has been accomplished with BINAM-derived bisurea catalysts, presenting up to four NH hydrogen-bond donors (HBDs) for fluoride. These catalysts bring insol. CsF and KF into soln., control fluoride nucleophilicity, and provide a chiral microenvironment for enantioselective fluoride delivery to the electrophile. These attributes encouraged a 1H/19F NMR study to gain information on hydrogen-bonding networks with fluoride in soln., as well as how these arrangements impact the efficiency of catalytic nucleophilic fluorination. Herein, NMR expts. enabled the detn. of the no. and magnitude of HB contacts to fluoride for thirteen bisurea catalysts. These data supplemented by diagnostic coupling consts. 1hJNH···F- give insight into how multiple H bonds to fluoride influence reaction performance. In dichloromethane (DCM-d2), nonalkylated BINAM-derived bisurea catalyst engages two of its four NH groups in hydrogen bonding with fluoride, an arrangement that allows effective phase-transfer capability but low control over enantioselectivity for fluoride delivery. The more efficient N-alkylated BINAM-derived bisurea catalysts undergo urea isomerization upon fluoride binding and form dynamically rigid trifurcated hydrogen-bonded fluoride complexes that are structurally similar to their conformation in the solid state. Insight into how the countercation influences fluoride complexation is provided based on NMR data characterizing the species formed in DCM-d2 when reacting a bisurea catalyst with tetra-n-butylammonium fluoride (TBAF) or CsF. Structure-activity anal. reveals that the three hydrogen-bond contacts with fluoride are not equal in terms of their contribution to catalyst efficacy, suggesting that tuning individual electronic environment is a viable approach to control phase-transfer ability and enantioselectivity.
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37. 37
  D’Abrosca, B.; Fiorentino, A.; Golino, A.; Monaco, P.; Oriano, P.; Pacifico, S. Carexanes: Prenyl Stilbenoid Derivatives from Carex distachya. Tetrahedron Lett. 2005, 46, 5269– 5272, DOI: 10.1016/j.tetlet.2005.06.036
  37
  Carexanes: prenyl stilbenoid derivatives from Carex distachya
  D'Abrosca, Brigida; Fiorentino, Antonio; Golino, Annunziata; Monaco, Pietro; Oriano, Palma; Pacifico, Severina
  Tetrahedron Letters (2005), 46 (32), 5269-5272CODEN: TELEAY; ISSN:0040-4039. (Elsevier B.V.)
  Metabolites with a new mol. skeleton, named carexane, have been isolated from the leaves of Carex distachya. The structures have been detd. on the basis of the spectroscopic characteristics of the compds. Bidimensional NMR has furnished important data useful for the characterization and the stereochem. of the mols. The compds. have a tetracyclic skeleton derived from the coupling of the prenyl moiety on a stilbenoid structure.
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38. 38
  Martín-Torres, I.; Ogalla, G.; Yang, J.-M.; Rinaldi, A.; Echavarren, A. M. Enantioselective Alkoxycyclization of 1,6-Enynes with Gold(I)-Cavitands: Total Synthesis of Mafaicheenamine C. Angew. Chem., Int. Ed. 2021, 60, 9339– 9344, DOI: 10.1002/anie.202017035
  38
  Enantioselective Alkoxycyclization of 1,6-Enynes with Gold(I)-Cavitands: Total Synthesis of Mafaicheenamine C
  Martin-Torres, Inmaculada; Ogalla, Gala; Yang, Jin-Ming; Rinaldi, Antonia; Echavarren, Antonio M.
  Angewandte Chemie, International Edition (2021), 60 (17), 9339-9344CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  Chiral gold(I)-cavitand complexes have been developed for the enantioselective alkoxycyclization of 1,6-enynes. This enantioselective cyclization has been applied for the first total synthesis of carbazole alkaloid (+)-mafaicheenamine C (I) and its enantiomer, establishing its configuration as R. The cavity effect was also evaluated in the cycloisomerization of dienynes. A combination of expts. and theor. studies demonstrates that the cavity of the gold(I) complexes forces the enynes to adopt constrained conformations, which results in the high obsd. regio- and stereoselectivities.
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39. 39
  Witham, C. A.; Mauleón, P.; Shapiro, N. D.; Sherry, B. D.; Toste, F. D. Gold(I)-Catalyzed Oxidative Rearrangements. J. Am. Chem. Soc. 2007, 129, 5838– 5839, DOI: 10.1021/ja071231+
  39
  Gold(I)-catalyzed oxidative rearrangements
  Witham, Cole A.; Mauleon, Pablo; Shapiro, Nathan D.; Sherry, Benjamin D.; Toste, F. Dean
  Journal of the American Chemical Society (2007), 129 (18), 5838-5839CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  A series of gold(I)-catalyzed oxidative rearrangement reactions of alkynes using sulfoxides as stoichiometric oxidants are reported. The reactions were postulated to proceed through intermol. oxygen atom transfer from the sulfoxide to gold(I)-carbenoid intermediates. Under the conditions for gold(I)-catalyzed oxidative rearrangement, 1,6-enynes were isomerized to cyclopropyl aldehydes, homopropargyl azides produced pyrrolones, acetylenic α-diazoketones formed cyclic en-1,4-diones, and propargyl esters produced 2-acyloxyenals.
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40. 40
  Wang, W.; Yang, J.; Wang, F.; Shi, M. Axially Chiral N-Heterocyclic Carbene Gold(I) Complex Catalyzed Asymmetric Cycloisomerization of 1,6-Enynes. Organometallics 2011, 30, 3859– 3869, DOI: 10.1021/om2004404
  40
  Axially chiral n-heterocyclic carbene gold(I) complex catalyzed asymmetric cycloisomerization of 1,6-enynes
  Wang, Wenfeng; Yang, Jinming; Wang, Feijun; Shi, Min
  Organometallics (2011), 30 (14), 3859-3869CODEN: ORGND7; ISSN:0276-7333. (American Chemical Society)
  A new class of axially chiral NHC-Au(I) complexes I [2-11; R1 = Me, PhCH2; R2 = H, R3 = PhCH2, Ac, PhCO, Boc, N-Boc-L-prolyl, N-Boc-D-prolyl; R2-R3 = (CH2)4, :CH-2-HOC6H4, :CHPh; R2, R3 = Me, PhCH2] and 2,2'-bis-benzimidazolylidene complex (1) were developed from optically active BINAM and fully characterized by NMR, ESI-MS, and IR spectroscopic data, and x-ray structures for three of the complexes. Gold(I) center exhibits a nearly linear coordination geometry. Within the carried out investigations herein, the sterically less hindered gold(I) complex, having a 1-pyrrolidinyl group in the 2'-position, was shown to be the best catalyst in asym. acetoxycyclization of 1,6-azaenyne HC≡CCH2NTsCH2CH:CHPh (52a), giving product 3-(acetoxyphenylmethyl)4-methylene-1-tosylpyrrolidine (53a) in >99% yield with 59% ee at 0°, and the sterically less hindered gold(I) catalyst (aS)-2a (shown as I, R1 = Me, R2 = H, R3 = Ac) is the best catalyst in the asym. oxidative rearrangement of 1,6-enynes, affording the corresponding aldehydes, 6-R-3-(arylsulfonyl)-3-azabicyclo[3.1.0]hexane-1-carboxaldehydes (56a,c-g; R = Ph, mesityl, CH2tBu; aryl = p-tolyl, 4-BrC6H4, 4-NO2C6H4, 2,4,6-iPr3C6H2) and 6-phenyl-3-oxabicyclo[3.1.0]hexane-1-carboxaldehyde (56h) in excellent yields (up to >99%) and modest enantioselectivities (3.1-70% ee) using PhCl as the solvent at 10°.
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41. 41
  (a) Yao, T.; Zhang, X.; Larock, R. C. AuCl₃-Catalyzed Synthesis of Highly Substituted Furans from 2-(1-Alkynyl)-2-alken-1-ones. J. Am. Chem. Soc. 2004, 126, 11164– 11165, DOI: 10.1021/ja0466964
  41a
  AuCl3-Catalyzed synthesis of highly substituted furans from 2-(1-alkynyl)-2-alken-1-ones
  Yao, Tuanli; Zhang, Xiaoxia; Larock, Richard C.
  Journal of the American Chemical Society (2004), 126 (36), 11164-11165CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  Highly substituted furans, e.g., I, have been synthesized by the reaction of 2-(1-alkynyl)-2-alken-1-ones and various nucleophiles under very mild reaction conditions in good to excellent yields. Gold and some other transition metals were efficient catalysts for this reaction.
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  (b) Rauniyar, V.; Wang, Z. J.; Burks, H. E.; Toste, F. D. Enantioselective Synthesis of Highly Substituted Furans by a Copper(II)-Catalyzed Cycloisomerization-Indole Addition Reaction. J. Am. Chem. Soc. 2011, 133, 8486– 8489, DOI: 10.1021/ja202959n
  41b
  Enantioselective Synthesis of Highly Substituted Furans by a Copper(II)-Catalyzed Cycloisomerization-Indole Addition Reaction
  Rauniyar, Vivek; Wang, Z. Jane; Burks, Heather E.; Toste, F. Dean
  Journal of the American Chemical Society (2011), 133 (22), 8486-8489CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)
  A catalytic enantioselective reaction based on a copper(II) catalyst strictly contg. chiral anionic ligands is described. In the present work, copper(II)-phosphate catalyst promotes the intramol. heterocyclization of 2-(1-alkynyl)-2-alkene-1-ones and facilitates high levels of enantioselectivity in the subsequent nucleophile attack resulting in highly substituted furans, e.g., I. Mechanistic studies suggest that formation of a copper(II)-indole species is important for catalysis.
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  (c) Force, G.; Ki, Y. L. T.; Isaac, K.; Retailleau, P.; Marinetti, A.; Betzer, J.-F. Paracyclophane-based Silver Phosphates as Catalysts for Enantioselective Cycloisomerization/Addition Reactions: Synthesis of Bicyclic Furans. Adv. Synth. Catal. 2018, 360, 3356– 3366, DOI: 10.1002/adsc.201800587
  41c
  Paracyclophane-based Silver Phosphates as Catalysts for Enantioselective Cycloisomerization/Addition Reactions: Synthesis of Bicyclic Furans
  Force, Guillaume; Ki, Yvette Lock Toy; Isaac, Kevin; Retailleau, Pascal; Marinetti, Angela; Betzer, Jean-Francois
  Advanced Synthesis & Catalysis (2018), 360 (17), 3356-3366CODEN: ASCAF7; ISSN:1615-4150. (Wiley-VCH Verlag GmbH & Co. KGaA)
  This manuscript discloses the first use of chiral phosphates based on C2-sym. paracyclophane scaffolds as chiral counterions in transition metal catalysis, showing that they may compare favorably with other known chiral phosphates, such as the TRIP phosphate. The targeted catalytic reaction is a silver(I) promoted domino heterocyclization of 2-(1-alkynyl)-2-alken-1-one derivs., in the presence of C-, or N-nucleophiles, which provides an efficient access to substituted bicyclic furans. Results show that high levels of enantioselectivity can be attained with either paracyclophane-based phosphates or TRIP phosphates, when the nucleophilic reactants display N-H functions in appropriate positions, near to the nucleophilic center. Therefore, the involvement of H-bonding between the NH function and the phosphate in the enantio-detg. step is postulated.
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42. 42
  ³¹P{¹H} and ¹⁹F{¹H} NMR spectra remained unchanged, confirming that the chloride was not scavenged. See Supporting Information for details.
  There is no corresponding record for this reference.
43. 43
  (a) Burés, J. A Simple Graphical Method to Determine the Order in Catalyst. Angew. Chem., Int. Ed. 2016, 55, 2028– 2031, DOI: 10.1002/anie.201508983
  43a
  A Simple Graphical Method to Determine the Order of a Reaction in Catalyst
  Bures, Jordi
  Angewandte Chemie, International Edition (2016), 55 (6), 2028-2031CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A graphical anal. to elucidate the order in catalyst is presented. This anal. uses a normalized time scale, t [cat]Tn, to adjust entire reaction profiles constructed with concn. data. The method is fast and simple to perform because it directly uses the concn. data, therefore avoiding the data handling that is usually required to ext. rates. Compared to methods that use rates, the normalized time scale anal. requires fewer expts. and minimizes the effects of exptl. errors by using information on the entire reaction profile.
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  (b) Burés, J. Variable Time Normalization Analysis: General Graphical Elucidation of Reaction Orders from Concentration Profiles. Angew. Chem., Int. Ed. 2016, 55, 16084– 16087, DOI: 10.1002/anie.201609757
  43b
  Variable Time Normalization Analysis: General Graphical Elucidation of Reaction Orders from Concentration Profiles
  Bures, Jordi
  Angewandte Chemie, International Edition (2016), 55 (52), 16084-16087CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  The recent technol. evolution of reaction monitoring techniques has not been paralleled by the development of modern kinetic analyses. The analyses currently used disregard part of the data acquired, thus requiring an increased no. of expts. to obtain sufficient kinetic information for a given chem. reaction. Herein, we present a simple graphical anal. method that takes advantage of the data-rich results provided by modern reaction monitoring tools. This anal. uses a variable normalization of the time scale to enable the visual comparison of entire concn. reaction profiles. As a result, the order in each component of the reaction, as well as kobs , is detd. with just a few expts. using a simple and quick math. data treatment. This anal. facilitates the rapid extn. of relevant kinetic information and will be a valuable tool for the study of reaction mechanisms.
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  (c) Nielsen, C. D.-T.; Burés, J. Visual Kinetic Analysis. Chem. Sci. 2019, 10, 348– 353, DOI: 10.1039/C8SC04698K
  43c
  Visual kinetic analysis
  Nielsen, Christian D.-T.; Bures, Jordi
  Chemical Science (2019), 10 (2), 348-353CODEN: CSHCCN; ISSN:2041-6520. (Royal Society of Chemistry)
  Visual kinetic analyses ext. meaningful mechanistic information from exptl. data using the naked-eye comparison of appropriately modified progress reaction profiles. Basic kinetic information is obtained easily and quickly from just a few expts. Therefore, these methods are valuable tools for all chemists working in process chem., synthesis or catalysis with an interest in mechanistic studies. This minireview describes the visual kinetic analyses developed in the last fifteen years and provides answers to the most common queries of new users. Furthermore, a video tutorial is attached detailing the implementation of both VTNA and RPKA.
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44. 44
  Briggs, G. E.; Haldane, J. B. S. A Note on the Kinetics of Enzyme Action. Biochem. J. 1925, 19, 338– 339, DOI: 10.1042/bj0190338
  44
  Note on the kinetics of enzyme action
  Briggs, G. E.; Haldane, J. B. S.
  Biochemical Journal (1925), 19 (), 338-9CODEN: BIJOAK; ISSN:0264-6021.
  A criticism of Michaelis and Menton's equation (C. A. 7, 2232) for enzyme action.
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  Application of this model rests on a series of underlying assumptions, all satisfied in the present case (see Supporting Information).
45. 45
  (a) Michaelis, L.; Menten, M. L. Die Kinetik der Invertinwirkung. Biochem. Z. 1913, 49, 333– 369
  45a
  Kinetics of Invertase Action
  Michaelis, L.; Menten, Maud L.
  Biochemische Zeitschrift (1913), 49 (), 333-69CODEN: BIZEA2; ISSN:0366-0753.
  The course of sugar inversion by invertase is consistent with the assumption that saccharose and enzyme unite to form a combination, of which the dissociation const. is 0.0167. The comp. is labile and breaks up into 1 mol. each of glucose, fructose, and invertin. Invertin has an affinity for glucose and fructose, as well as for other carbohydrates and higher alcs. (mannitol and glycerol), although in none of these cases is the affinity so great as for saccharose. The compds. formed with these substs. are not labile and the substs. do not suffer decomp. They show their combining capacity for the enzyme by the fact that their presence retards the inversion of saccharose by invertin. The concs. of all the invertin-carbohydrate compds. were calc. according to the law of mass action and the dissociation consts. detd. The decomp. of the saccharose-invertin compd. being a monomol. reaction, the inversion velocity at any time is directly proportional to the conc. of the compd. From the above assumptions a differential equation is derived which agrees well with the observed inversion rates of saccharose.
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  (b) Johnson, K. A.; Goody, R. S. The Original Michaelis Constant: Translation of the 1913 Michaelis−Menten Paper. Biochemistry 2011, 50, 8264– 8269, DOI: 10.1021/bi201284u
  45b
  The Original Michaelis Constant: Translation of the 1913 Michaelis-Menten Paper
  Johnson, Kenneth A.; Goody, Roger S.
  Biochemistry (2011), 50 (39), 8264-8269CODEN: BICHAW; ISSN:0006-2960. (American Chemical Society)
  Nearly 100 years ago Michaelis and Menten published their now classic paper in which they showed that the rate of an enzyme-catalyzed reaction is proportional to the concn. of the enzyme-substrate complex predicted by the Michaelis-Menten equation. Because the original text was written in German yet is often quoted by English-speaking authors, we undertook a complete translation of the 1913 publication, which we provide as Supporting Information. Here we introduce the translation, describe the historical context of the work, and show a new anal. of the original data. In doing so, we uncovered several surprises that reveal an interesting glimpse into the early history of enzymol. In particular, our reanal. of Michaelis and Menten's data using modern computational methods revealed an unanticipated rigor and precision in the original publication and uncovered a sophisticated, comprehensive anal. that has been overlooked in the century since their work was published. Michaelis and Menten not only analyzed initial velocity measurements but also fit their full time course data to the integrated form of the rate equations, including product inhibition, and derived a single global const. to represent all of their data. That const. was not the Michaelis const., but rather Vmax/Km, the specificity const. times the enzyme concn. (kcat/Km × E0).
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46. 46
  Blackmond, D. G. Reaction Progress Kinetic Analysis: A Powerful Methodology for Mechanistic Studies of Complex Catalytic Reactions. Angew. Chem., Int. Ed. 2005, 44, 4302– 4320, DOI: 10.1002/anie.200462544
  46
  Reaction progress kinetic analysis: A powerful methodology for mechanistic studies of complex catalytic reactions
  Blackmond, Donna G.
  Angewandte Chemie, International Edition (2005), 44 (28), 4302-4320CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Reaction progress kinetic anal. to obtain a comprehensive picture of complex catalytic reaction behavior is described. This methodol. employs in situ measurements and simple manipulations to construct a series of graphical rate equations that enable anal. of the reaction to be accomplished from a minimal no. of expts. Such an anal. helps to describe the driving forces of a reaction and may be used to help distinguish between different proposed mechanistic models. This Review describes the procedure for undertaking such anal. for any new reaction under study.
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  Correction:Blackmond, D. G. Angew. Chem., Int. Ed. 2006, 45, 2162– 2162, DOI: 10.1002/anie.200690050
  46
  Reaction progress kinetic analysis: A powerful methodology for mechanistic studies of complex catalytic reactions. [Erratum to document cited in CA143:132869]
  Blackmond, Donna G.
  Angewandte Chemie, International Edition (2006), 45 (14), 2162CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)
  A review. Ref. [29] should read as follows: T. Schultz, PhD Thesis, Universitat Basel (Switzerland), 2004.
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47. 47
  Franchino, A.; Montesinos-Magraner, M.; Echavarren, A. M. Silver-Free Catalysis with Gold(I) Chloride Complexes. Bull. Chem. Soc. Jpn. 2021, 94, 1099– 1117, DOI: 10.1246/bcsj.20200358
  47
  Silver-Free Catalysis with Gold(I) Chloride Complexes
  Franchino, Allegra; Montesinos-Magraner, Marc; Echavarren, Antonio M.
  Bulletin of the Chemical Society of Japan (2021), 94 (3), 1099-1117CODEN: BCSJA8; ISSN:0009-2673. (Chemical Society of Japan)
  A review. Gold(I) chloride complexes are stable, widespread precatalysts that generally require activation by halide abstraction to display useful catalytic activity. Chloride scavenging is typically performed in situ by using silver salts. This procedure, apart from mandating the use of an addnl. metal, often neg. impacts the reaction outcome, because Ag additives are not catalytically innocent (silver effect). Therefore, both the development of alternative chloride scavengers and the design of self-activating gold(I) chloride complexes endowed with special ligands have lately been the subject of intense research efforts. This describes recent advances in the field of silver-free Au(I) catalysis employing gold(I) chloride complexes, with an emphasis on approaches emerged in the last decade.
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48. 48
  Lineweaver, H.; Burk, D. The Determination of Enzyme Dissociation Constants. J. Am. Chem. Soc. 1934, 56, 658– 666, DOI: 10.1021/ja01318a036
  48
  Determination of enzyme dissociation constants
  Lineweaver, Hans; Burk, Dean
  Journal of the American Chemical Society (1934), 56 (), 658-66CODEN: JACSAT; ISSN:0002-7863.
  Graphical methods involving const. slopes and straight-line extrapolations have been developed for testing and interpreting kinetic data and for detg. dissocn. consts. of enzyme-substrate and enzyme-inhibitor compds. and other related consts. when the data are found to be consistent with an assigned mechanism. Representative analyses are given for invertase, raffinase, amylase, citric dehydrogenase, catalase, oxygenase, esterase and lipase, involving substrate activation, substrate inhibition, general competitive and noncompetitive inhibition, steady states and reactions of various orders. The various methods described are applicable to gen. chem. catalysis, homogeneous or heterogeneous.
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49. 49
  The uncertainty refers not to experimental variation but only to the mathematical error of the linear regression, as determined by Excel LINEST routine. If all data from time 0 to 10 h are used in the Lineawer–Burk plot, a K_M value of 63 ± 4 is obtained, leading to identical conclusions regarding the partial order in substrate (see Supporting Information).
  There is no corresponding record for this reference.
50. 50
  Burés, J. What is the Order of a Reaction?. Top. Catal. 2017, 60, 631– 633, DOI: 10.1007/s11244-017-0735-y
  50
  What is the Order of a Reaction?
  Bures, Jordi
  Topics in Catalysis (2017), 60 (8), 631-633CODEN: TOCAFI; ISSN:1022-5528. (Springer)
  The order of a reaction in some species seems an obvious, trivial concept that all chemists master. However, in complex situations such as catalytic systems, the order of a reaction is not always that simple: it can be partial, neg. and function of other parameters. In order to analyze rate laws and exptl. orders of complex reaction networks, it is necessary to have a proper math. description of what the order of a reaction is. In general, chemists working in catalysis are unaware that such a math. description exists and therefore they are restricted to analyzing only extreme limit cases of rate laws. This manuscript offers a description and a simple demonstration of this concept, known as elasticity coeff. or normalized sensitivity. It also presents several examples of applications on classic and usual catalytic scenarios.
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51. 51
  Geometry optimizations were carried out using Gaussian 09 at the B3LYP-D3/6-31G(d,p) level of theory in toluene (SMD). Single point energy calculations were performed on the resulting structures employing B3LYP-D3/6-311+G(d,p)/SMD(toluene). See the Supporting Information for an overview of all computed structures. Refer to ref (12c) for an excellent discussion of alternative computational methods (functionals, basis sets, solvent models) in the context of chiral phosphate–iminium ion pairs.
  There is no corresponding record for this reference.
52. 52
  This step is assumed to be enantiodetermining on the basis of previous DFT calculations for the same reactions (refs (26) and (27e)).
  There is no corresponding record for this reference.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/jacs.1c11978.
- Optimization tables, procedures, characterization, kinetic data, NMR spectra, SFC and HPLC traces, DFT computations, crystallographic data (PDF)
- ja1c11978_si_001.pdf (25.01 MB)
Accession Codes
CCDC 2107746–2107758 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

H-Bonded Counterion-Directed Enantioselective Au(I) CatalysisClick to copy article linkArticle link copied!

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Generality of the Enantioselective 5-exo-dig and 6-exo-dig Cyclizations

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H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis
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