
Web Release Date: September 27,
Synthesis of Anthropomorphic Molecules: The NanoPutians
Department of Chemistry and Center for Nanoscale Science and Technology, MS 222, Rice University, Houston, Texas 77005
Received June 27, 2003
Abstract:
Described here are the synthetic details en route to an array of 2-nm-tall anthropomorphic molecules in monomeric, dimeric, and polymeric form. These anthropomorphic figures are called, as a class, NanoPutians. Using tools of chemical synthesis, the ultimate in designed miniaturization can be attained while preparing the most widely recognized structures: those that resemble humans.
Using tools of chemical synthesis, the ultimate in
designed miniaturization can be attained. Beyond the
molecular-sized domain there is no conceivable entity
upon which to tailor architectures that could have
programmed cohesive interactions between the individual
building blocks. It is at this size region that synthetic
chemists have been inherently captivated; however, their
fascination is rarely shared by the layperson. The masses
view chemical structures as difficult-to-grasp abstractions
formulated by complex algorithms, except when molecules resemble macroscopic objects such as C60. Arguably, the most widely recognized structures are those that
resemble humans.1 Here we describe the synthetic details
en route to an array of 2 nm-tall anthropomorphic
molecules, both in monomeric and polymeric form.2,3
Accepted common names such as "cubane", "dodecahedrane", "housane", and "chair-form" describe the constitution or conformation of cycloalkanes while "buckminsterfullerene" expresses chemical structure by its relation to the artisan that built macroscopic analogues. Utilizing such a license, the anthropomorphic molecules here are dubbed, as a class, NanoPutians, following the lead of the Lilliputians in Jonathan Swift's classic, Gulliver's Travels. More descriptive names follow here for each molecule type. Likewise, references to "head", "tail", "northwest region", and "warhead", for instance, are used by synthetic chemists to describe moieties or functions within a target molecule. In the same vein, we extend the concept to body-part-like descriptions such as "head", "neck", and "legs". Furthermore, realizing that many molecule types, for example, terpenes, are routinely drawn in nonequilibrium conformations to enhance their rapid cognitive classification, nonequilibrium conformations are shown here for some structures. However, the liberties we take with the nonequilibrium conformational drawings are only minor when representing the main structural portions; conformational license is only used, in some cases, with the NanoPutians' head dressings.
2.1. Synthesis of NanoKid. The first of the NanoPutians was prepared via a separate synthesis of the top and bottom body-portions followed by adjoining at the "waist", thereby constituting a convergent synthetic approach. The top-half was made as shown in Scheme 1.
| Scheme 1. Synthesis of a NanoPutian's Upper Bodya a TEA = triethylamine. |
1,4-Dibromobenzene was iodinated in good yield.4 3,3-Dimethylbutyne was then coupled to 1 to give 2. Formylation5 of 2 was accomplished by lithium-halogen exchange followed by quenching with DMF to afford the aldehyde 3. The aldehyde was protected as the acetal using 1,2-ethanediol in a presence of a catalytic amount of p-toluenesulfonic acid with azeotropic removal of the water via a Dean-Stark trap. Attempts to couple 4 to alkynes (vide infra) gave a low yield (<10%) of the desired products due to the poor reactivity of the bromoarene in the presence of the sterically encumbering ortho moiety. The bromide was therefore exchanged with an iodide by lithium-halogen exchange and quenching with 1,2-diiodoethane to afford 5 as the top-body portion.
For the preparation of the lower-body segment, nitroaniline was brominated to afford 6 that was further
converted to the diazonium salt and reduced to remove
the diazo moiety (Scheme 2). Conversion of the nitro
group to the amine afforded 8.6 Sandmeyer reaction was
then used to make the diazonium salt followed by
iodination7
| Scheme 2. Synthesis of NanoPutian's Lower Body |
The last step in the synthesis involves the coupling of the top and bottom portions. This was accomplished by once again using the Pd/Cu-catalyzed protocol8 to afford NanoKid (13), each with the structure shown in Scheme 3.
2.2. Synthesis of the NanoProfessional NanoPutians. NanoKid (13) can now serve as the "progenitor" of the NanoProfessionals.
A facile procedure using microwave irradiation9-12 was
used for the head-conversion reactions. NanoKid (13)
with an excess of a 1,2- or 1,3-diol, in the presence of a
).
This includes NanoAthlete (14), NanoPilgrim (15), NanoGreenBeret (16), NanoJester (17), NanoMonarch (18), NanoTexan (19) NanoScholar (20), and NanoBaker (21). By using this microwave irradiation method, longer reaction times are obviated. Decomposition resulted when the NanoChef (22) synthesis was attempted under the microwave conditions (Table 1, entry 9). This was probably due to phenol-aldehyde-like polymerization involving the electron-rich catechol and the aldehyde-based oxonium intermediate. Rather, a procedure employing catechol and chlorotrimethylsilane was efficacious,13 albeit low yielding. The NanoPutians were characterized using spectroscopic and mass spectrometric analysis.
In a separate combinatorial experiment, we sought to
make the entire NanoPutian population at once by
starting with NanoKid (13) and adding all the appropriate diols (except catechol) in a single flask to generate
14-21
The stick figure drawn for 13 in Scheme 3 is similar to a molecular mechanics energy-minimized form of 13 in Figure 2. The rigidity of the backbone molecular structure causes the conformation to be quite similar to the visually recognizable form drawn.
| Figure 2 NanoKid (13) in its energy-minimized conformation that was determined using molecular mechanics (Spartan). |
2.3. Synthesis of the NanoToddler. Following the same route as for NanoKid (13), but using a truncated lower half (24), NanoToddler (25) was synthesized (Scheme 4).
1-Butyne was coupled to 10 to give 23 in good yield, followed by deprotection with potassium carbonate and methanol. Compounds 5 and 24 were then coupled to afford the NanoToddler (25) in 78% yield.
2.4. Synthesis of a Standing Array. As described in Scheme 5, 3-butyn-1-ol was converted to the mesylate14 26 and then converted to the thiolacetate 27 using the cesium salt.15 The free alkyne 27 was then coupled8 to 10 to furnish 28. The trimethylsilyl group was removed, and then the resulting free alkyne 29 was coupled to 5. The NanoKid with protected thiol feet, 30, was obtained then permitted to self-assemble on a gold surface (Figure 3).
The acetyl protecting groups were removed by a solution of ammonium hydroxide in THF to give the free thiols or thiolates. A gold-plated substrate (Si/Cr/Au) was then dipped into this solution, and after incubating for 4 days, the resultant surface was rinsed and the thickness was measured by ellipsometry. This compound formed a self-assembled monolayer (SAM) with an ellipsometrically measured thickness of 1.97 nm compared to a calculated thickness of 2.11 nm along the surface normal; the difference was indicative of the routinely observed sp3-sulfur hybridization and intermolecular interaction-induced tilt angle from the surface normal.
2.5. Synthesis of NanoBalletDancers. Scheme 6
outlines the synthesis of the NanoBalletDancers. 2,5-Dibromoaniline was diiodinated.16 The resulting aniline
31 was then diazotized and reduced. Compound 32 was
coupled to 3,3-dimethylbutyne to furnish 33,
| Scheme 6. Synthesis of the NanoBalletDancers' Upper Body |
The bottom half was obtained by formylation of dibromoiodobenzene (9) to give 37 (Scheme 7). Activation of the bromides by the aldehyde for the Sonogashira8 coupling permitted an excellent yield in the cross-coupling to afford 38.
| Scheme 7. Synthesis of the NanoBalletDancers' Lower Body |
Compound 36 was lithiated and quenched with the aldehyde 38 to give the alcohol 39 (Scheme 8). Following a procedure by Hart,17 the alcohol was converted to the xanthate 40. Reduction with tri-n-butyltin hydride in the presence of a catalytic amount of AIBN afforded the NanoBalletDancer 41 in fair yield. The synthesis of a second dancer was carried out by microwave-induced acetal exchange to furnish the NanoBalletDancer 42.
| Scheme 8. Last Synthetic Steps toward the NanoBalletDancers |
2.6. Synthesis of a NanoPutian Chain. In an effort to unite the NanoPutians into an extended "hand-holding" chain, an AB-polymer target was sought (Figure 4).
| Figure 4 AB-polymer configuration of the NanoPutian chain. |
The synthesis of the NanoPutians with "hand" moieties for the chain starts with the coupling of dibromodiiodobenzene (1) to the protected alkyne 43 (Scheme 9) (obtained by treatment of 3-butyn-1-ol with tert-butyldimethylsilyl chloride) to afford 44 in excellent yield. As before, the aldehyde moiety was added via lithiation followed by quenching with DMF to furnish 45.
| Scheme 9. Synthesis of the Upper Part of the NanoPutian Chain |
Sonogashira8 coupling of the aldehyde 45 with the lower body half 12 was accomplished in excellent yield to afford 46 (Scheme 10). Acetal formation using the conventional method of azeotropic removal of water with a Dean-Stark trap gave a poor yield of 6%. However, using chlorotrimethylsilane13 followed by the deprotection of the alcohols using TBAF furnished 47, the hydroxyl-tipped NanoKid, in 36% over the two steps. Some removal of the TBS-protecting group occurred in the first step. Compound 47 appears to be sensitive to moisture and possibly light; hence, it should be used immediately or stored appropriately. Using the same procedure, the aldehyde 46 was converted to 48, the hydroxyl-tipped NanoAthlete, in good yield. Here again, a majority of the TBS protecting groups were removed in the acetalization step. To have an ester linkage between 47 and 48, one of the two compounds needed to be oxidized. However, several attempts to oxidize the alcohols failed to cleanly afford the diacid. To circumvent the oxidation problem, the structure of the target polymer was modified; the ester linkage was replaced by a carbonate moiety (Scheme 11).
Following a procedure by Konakahara,18 the p-nitrophenylchloroformate (49) was synthesized using diphosgene and Hünig's base. This chloroformate was then
coupled to the alcohol 48 to give 50 in very good yield.19-22
", is the bonding pattern between any two
NanoPutians, then the arm directions in these products
are as follows: 51 is down-up
up-down, 52 is up-down
up-down, and AB-polymer 53 consists of three
regioisomeric bonding patterns, namely down-up
up-down, up-down
up-down, and up-down
down-up
(Scheme 11). In 51 there is a mirror plane between the
two parts of the dimer (except the heads). In 52, there is
an axis of symmetry down the middle of the dimer (except
for the heads). 51 (less polar) and 52 were the only two
non-baseline spots by TLC using 1:1 EtOAc/hexane.
Compounds 51 and 52, after flash chromatography, had
Mn = 775 and 745 with Mw = 800 and 765, respectively,
by size-exclusion chromatography (SEC) relative to polystyrene. Their actual molecular weights of 1130.5 were
confirmed by mass spectrometry (MALDI) for each. The
silica gel chromatographic baseline material consisted of
higher oligomers and polymers which were then flushed
from the chromatography column using EtOAc. LDI-MS
showed a range of peaks centered around 47 500 which
corresponds to the 42-mer, while the SEC showed 53 to
have Mn = 23 500 and a Mw = 36 600, relative to
polystyrene.
In conclusion, a series of monomeric, dimeric, and polymeric anthropomorphic molecules have been synthesized. These anthropomorphic entities are dubbed NanoPutians, as a class. Furthermore, they are assigned common names based on their individual anthropomorphic designs. These represent the ultimate in anthropomorphic design miniaturization.
2,5-Bis(3,3-dimethylbutynyl)-1,4-dibromobenzene (2).
See the Pd/Cu general procedure (Supporting Information). To
a solution of 2,5-dibromo-1,4-diiodobenzene (4.29 g, 8.79
mmol), bis(triphenylphosphine)palladium(II) dichloride (0.379
g, 0.541 mmol), and copper(I) iodide (0.206 g, 1.08 mmol) in
THF (40 mL) were added Et3N (20 mL) and cold (0
C) 3,3-dimethyl-1-butyne (2.22 mL, 18.03 mmol). The mixture was
stirred at 23
C for 20 h in a screwcap vial. Purification by
flash chromatography (silica gel, hexanes) afforded 2.43 g (70%
yield) of the title compound as a white solid. Mp: 154-158
C. IR (KBr): 2969, 2922, 2896, 2864, 2243, 2208, 1463, 1359,
1264, 1200, 1061 cm-1. 1H NMR (400 MHz, CDCl3):
7.59 (s,
2 H), 1.34 (s, 18 H). 13C NMR (100 MHz, CDCl3):
135.8,
126.3, 123.7, 106.0, 30.7, 28.4. HRMS: calcd for C18H20Br2
393.9932, found 393.9917.
2,5-Bis(3,3-dimethylbutynyl)-4-bromobenzaldehyde (3).
To a solution of 2,5-bis(3,3-dimethylbutynyl)-1,4-dibromobenzene (2.43 g, 6.135 mmol) in THF (30 mL) cooled to -78
C
under nitrogen was added dropwise n-BuLi (2.48 M, 2.72 mL).
The reaction mixture was allowed to stir at -78
C for 1 h. To
this mixture was added DMF (0.48 mL, 6.135 mmol) predried
over molecular sieves. The reaction mixture was allowed to
stir for another 1 h and then warmed to room temperature
for 4 h. It was then diluted with water and extracted with
Et2O. The combined organic phases were washed with brine,
dried over MgSO4, filtered, and evaporated. Purification by
flash chromatography (silica gel, hexanes/CH2Cl2 1/1) afforded
1.77 g (83% yield) of the title compound as a white solid. Mp:
98-102
C. IR (KBr): 2967, 2926, 2897, 2865, 2837, 2735,
2239, 2213, 1699, 1586, 1520, 1466, 1380, 1362, 1010 cm-1.
1H NMR (400 MHz, CDCl3):
10.31 (s, 1 H), 7.76 (s, 1 H),
7.58 (s, 1 H), 1.28 (s, 9 H), 1.27 (s, 9 H). 13C NMR (100 MHz,
CDCl3):
190.0, 136.2, 134.1, 131.1, 130.7, 126.6, 125.9, 107.8,
105.7, 77.1, 73.6, 30.5, 28.2, 28.1. HRMS: calcd for C19H21OBr 344.0776, found 344.0772.
2,5-Bis(3,3-dimethylbutynyl)-4-(1,3-dioxolane)bromobenzene (4). To a round-bottom flask equipped with a Dean-Stark trap for azeotropic removal of the water were added 2,5-(3',3'-dimethylbutynyl)-4-bromobenzenaldehyde (16.14 g, 46.746
mmol), ethylene glycol (5.20 mL, 93.49 mmol), p-toluenesulfonic acid (0.133 g, 0.701 mmol), and toluene (50 mL). The
reaction mixture was heated to reflux for 3 d. It was then
diluted with water. The pH was adjusted to 10 with 50%
NaOH, and the solution was extracted with ether. The
combined organic phases were dried over MgSO4, filtered, and
evaporated. Purification by flash chromatography (silica gel,
hexanes/CH2Cl2 60/40) afforded 13.98 g (77% yield) of the title
compound as a white solid. Mp: 128-134
C. IR (KBr): 2968,
2927, 2898, 2866, 2240, 1594, 1533, 1470, 1398, 1363, 1268,
1075 cm-1. 1H NMR (400 MHz, CDCl3):
7.60 (s, 1 H), 7.56
(s, 1 H), 6.06 (s, 1 H), 4.17 (m, 2 H), 4.03 (m, 2 H), 1.34 (s, 9
H), 1.32 (s, 9 H). 13C NMR (100 MHz, CDCl3):
137.6, 135.4,
130.4, 125.6, 125.2, 123.6, 105.7, 104.7, 101.3, 77.9, 75.1, 65.4,
30.7, 28.3, 28.2. HRMS: calcd for C21H25O2Br 388.1038, found
388.1032. Anal. Calcd: C, 64.78; H, 6.47. Found: C, 64.91; H,
6.57.
2,5-Bis(3,3-dimethylbutynyl)-4-(1,3-dioxolane)iodobenzene (5). To a solution of 2,5-bis(3,3-dimethylbutynyl)-4-(1,3-dioxolane)bromobenzene (0.51 g, 1.310 mmol) in THF (25 mL)
cooled to -78
C under nitrogen was added dropwise n-BuLi
(2.48 M, 0.57 mL). The reaction mixture was allowed to stir
at -78
C for 30 min. To this solution was added a solution of
1,2-diiodoethane (0.554 g, 1.965 mmol) in THF (10 mL). The
reaction mixture was allowed to warm to rt overnight. It was
diluted with a saturated solution of sodium bicarbonate and
extracted with ether. The combined organic phases were
washed with brine, dried over MgSO4, filtered, and evaporated
in vacuo. Purification by flash chromatography (silica gel, CH2Cl2/hexanes 1/1) afforded 0.49 g (86% yield) of the title product
as a white solid. Mp: 172-178
C. IR (KBr): 2967, 2926, 2896,
2866, 2236, 1531, 1465, 1397, 1362, 1267, 1074 cm-1. 1H NMR
(400 MHz, CDCl3):
7.86 (s, 1 H), 7.51 (s, 1 H), 6.05 (s, 1 H),
4.16 (m, 2 H), 4.03 (m, 2 H), 1.35 (s, 9 H), 1.32 (s, 9 H). 13C
NMR (100 MHz, CDCl3):
141.7, 138.5, 129.6, 129.2, 123.5,
105.6, 103.9, 101.4, 101.3, 81.7, 74.8, 65.4, 30.8, 30.7, 28.3, 28.3.
HRMS: calcd for C21H25IO2 436.0899, found 436.0895.
3,5-Dibromoiodobenzene (9). 3,5-Dibromoaniline (13.0 g,
51.8 mmol) was dissolved in concentrated sulfuric acid (100
mL) at 50
C. After the solution was cooled to 0
C, sodium
nitrite (7.15 g, 103.62 mmol) was added portionwise with
continuous stirring, maintaining the temperature below 5
C.
The reaction mixture was allowed to stir at 0
C for 2 h. The
solution was poured onto ice, and KI (25.80, 155.43 mmol) in
125 mL of water was added. The mixture was then heated to
80
C for 15 min. The solid was removed by filtration and
washed with cold water. Recrystallization from ethanol gave
an orange solid (13.20 g, 70% yield). Mp: 120-126
C. IR
(KBr): 3095, 3061, 1547, 1398, 1096 cm-1. 1H NMR (400 MHz,
CDCl3):
7.80 (d, J = 1.7 Hz, 2 H), 7.65 (t, J = 1.7 Hz, 2 H).
13C NMR (100 MHz, CDCl3):
138.5, 133.6, 123.4, 94.4 ppm.
HRMS: calcd for C6H3Br2I 359.7646, found 359.7652.
3,5-Dibromo(trimethylsilylethynyl)benzene (10). See
the Pd/Cu general procedure (Supporting Information). To a
solution of 3,5-dibromoiodobenzene (13.20 g, 36.484 mmol), bis(triphenylphosphine)palladium(II) dichloride (1.023 g, 1.46
mmol),and copper(I) iodide (0.694 g, 3.644 mmol) in THF (130
mL) were added Et3N (40 mL) and trimethylsilylacetylene
(5.19 mL, 36.484 mmol). The mixture was stirred at rt for 2 d.
Purification by flash chromatography (silica gel, hexanes)
afforded 11.0 g (91% yield) of the title compound as a clear
liquid. IR (NaCl): 3074, 2960, 2898, 2167, 1578, 1540, 1419,
1402, 1250, 1103 cm-1. 1H NMR (400 MHz, CDCl3):
7.62 (t,
J = 1.8 Hz, 1 H), 7.59 (d, J = 1.8 Hz, 2 H), 0.25 (s, 9 H). 13C
NMR (100 MHz, CDCl3):
134.2, 133.33, 126.5, 122.5, 101.6,
97.6, -0.3. HRMS: calcd for C11H12Br2Si 331.9056, found
331.9053.
3,5-(1'-Pentynyl)-1-(trimethylsilylethynyl)benzene (11).
See the Pd/Cu general procedure (Supporting Information). To
a solution of bis(triphenylphosphine)palladium(II) dichloride
(0.926 g, 1.32 mmol), copper(I) iodide (0.628 g, 3.30 mmol) in
THF (100 mL), and Et3N (70 mL) were added 3,5-dibromo(trimethylsilylethynyl)benzene (11.0 g, 33.12 mmol) via a
cannula and 1-pentyne (6.86 mL, 69.56 mmol). The mixture
was heated to 75
C for 3 d. After the mixture was checked by
TLC, additional bis(triphenylphosphine)palladium(II) dichloride (0.502 g, 0.716 mmol), copper(I) iodide (0.304 g, 1.59
mmol), THF (40 mL), Et3N (20 mL), and 1-pentyne (3.26 mL,
33.12 mmol) were added. The reaction mixture was allowed
to stir for another 20 h at 80
C. Purification by flash
chromatography (silica gel, hexanes) afforded 6.89 g of the title
compound as a clear liquid and 2.86 g of the monocoupled
product. This monocoupled product was taken to a reaction
flask with bis(triphenylphosphine)palladium(II) dichloride
(0.188 g, 0.269 mmol), copper(I) iodide (0.102 g, 0.538 mmol),
1-pentyne (1.2 mL, 12.17 mmol), and Et3N (30 mL) in THF
(40 mL). The mixture was stirred at 70
C for 3 d. After the
same purification method as above, it afforded 0.84 g of the
product. The overall yield for this reaction is 76%. IR (NaCl):
2963, 2934, 2902, 2872, 2836, 2233.6, 2155, 1581, 1460, 1413,
1250, 1171 cm-1. 1H NMR (400 MHz, CDCl3):
7.39 (d, J =
1.5 Hz, 2 H), 7.36 (t, J = 1.5 Hz, 1 H), 2.36 (t, J = 7.0 Hz, 4
H), 1.63 (sext, J = 7.2 Hz, 4 H), 1.04 (t, J = 7.3 Hz, 6 H), 0.25
(s, 9 H). 13C NMR (100 MHz, CDCl3):
134.4, 133.8, 124.4,
123.3, 103.7, 94.9, 91.2, 79.4, 22.1, 21.3, 13.5, -0.2. HRMS:
calcd for C21H26Si 306.1804, found 306.1806.
3,5-(1'-Pentynyl)-1-ethynylbenzene (12). See the general
alkyne deprotection procedure (Supporting Information). To
a solution of 3,5-(1-pentynyl)-1-(trimethylsilylethynyl)benzene
(1.729 g, 5.649 mmol) in MeOH (40 mL) and CH2Cl2 (40 mL)
was added K2CO3 (7.80 g, 56.49 mmol). The solution was
stirred at 23
C for 2 h. The reaction afforded 1.32 g (100%
yield) of the title compound as a yellow oil. IR (NaCl): 3295,
2963, 2933, 2872, 2835, 2234, 1582, 1461, 1415, 1380, 1340.
1H NMR (400 MHz, CDCl3):
7.41 (s, 3 H), 3.06 (s, 1 H), 2.37
(t, J = 7.0 Hz, 4 H), 1.62 (sext, J = 7.2 Hz, 4 H), 1.05 (t, J =
7.4 Hz, 6 H). 13C NMR (100 MHz, CDCl3):
134.8, 133.9,
124.6, 122.3, 91.5, 82.3, 79.2, 77.7, 22.0, 21.3, 13.5. HRMS:
calcd for C18H18 234.1408, found 234.1406.
NanoKid (13). See the Pd/Cu general procedure (Supporting Information). To a solution of 2,5-bis(3,3-dimethylbutynyl)-4-(1,3-dioxolane)iodobenzene (3.93 g, 9.017 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.253 g, 0.361 mmol),
and copper(I) iodide (0.137 g, 0.721 mmol) in THF (40 mL)
were added Et3N (20 mL) and 3,5-(1-pentynyl)-1-ethynylbenzene (2.07 g, 8.846 mmol) in THF (20 mL) via a cannula. The
mixture was stirred at 25
C for 16 h and at 34
C for 1 h.
Purification by flash chromatography (silica gel, hexanes/CH2Cl2 60/40) afforded 4.31 g of the title compound as a yellow oil
but was contaminated with 12% of 2,5-bis(3,3-dimethylbutynyl)-4-(1,3-dioxolane)iodobenzene. This contaminated material
was re-subjected to the reaction by adding 3,5-(1-pentynyl)-1-ethynylbenzene (0.299 g, 1.278 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.034 g, 0.048 mmol), copper(I)
iodide (0.020 g, 0.105 mmol), TEA (10 mL), and THF (60 mL).
The mixture was allowed to stir at 50
C for another 2 d.
Purification by flash chromatography (silica gel, hexanes/CH2Cl2 60/40) afforded 4.17 g (85% yield) of the title compound as
a sticky yellow solid. IR (NaCl, CHCl3): 2966, 2931, 2897,
2869, 2230, 1581, 1474, 1454, 1398 cm-1. 1H NMR (400 MHz,
CDCl3):
7.58 (s, 1 H), 7.53 (s, 1 H), 7.46 (d, J = 1.5 Hz, 2 H),
7.38 (t, J = 1.5 Hz, 1 H), 6.11 (s, 1 H), 4.19 (m, 2 H), 4.05 (m,
2 H), 2.38 (t, J = 7.0 Hz, 4 H), 1.60 (sext, J = 7.2 Hz, 4 H),
1.37 (s, 9 H), 1.34 (s, 9 H), 1.05 (t, J = 7.2 Hz, 6 H). 13C NMR
(100 MHz, CDCl3):
138.4, 135.4, 134.2, 133.6, 129.5, 125.7,
125.5, 124.5, 123.5, 122.3, 105.0, 104.2, 101.4, 92.0, 91.3, 88.4,
79.4, 77.8, 75.5, 65.5, 31.0, 30.8, 28.3, 22.1, 21.3, 13.5. HRMS:
calcd for C39H42O2 542.3185, found 542.3183. Anal. Calcd: C,
86.30; H, 7.80. Found: C, 86.27; H, 7.82.
NanoAthlete (14). In a small vial, NanoKid (13) (0.243 g,
0.448 mmol), p-toluenesulfonic acid monohydrate (0.003 g,
0.014 mmol), 2,2-dimethyl-1,3-propanediol (0.932 g, 8.956
mmol), and MgSO4 (0.113 g, 0.939 mmol) were subjected to
microwave irradiation for 7 min. The reaction mixture was
then diluted with a saturated solution of NaHCO3 and
extracted with ether. The combined organic phases were dried
over MgSO4, filtered, and evaporated in vacuo. Purification
by flash chromatography (silica gel, hexanes/CH2Cl2 60/40)
afforded 239 mg (91% yield) of the title compound as a yellow
sticky solid. IR (NaCl, CHCl3): 2965, 2930, 2900, 2867, 2228,
1580, 1455, 1401, 1384, 1362, 1267, 1108 cm-1. 1H NMR (400
MHz, CDCl3):
7.72 (s, 1 H), 7.53 (s, 1 H), 7.47 (d, J = 1.5
Hz, 2 H), 7.38 (t, J = 1.5 Hz, 1 H), 5.69 (s, 1 H), 3.80 (d, J =
11 Hz, 2 H), 3.64 (d, J = 11 Hz, 2 H), 2.38 (t, J = 7.0 Hz, 4 H),
1.62 (sext, J = 7.2 Hz, 4 H), 1.37 (s, 9 H), 1.36 (s, 9 H), 1.34 (s,
3 H), 1.05 (t, J = 7.2 Hz, 6 H), 0.81 (s, 3 H). 13C NMR (100
MHz, CDCl3):
138.9, 135.0, 134.1, 133.5, 129.3, 125.9, 125.3,
124.5, 123.5, 121.5, 104.4, 104.1, 99.7, 91.8, 91.2, 88.5, 79.4,
77.9, 77.9, 75.6, 31.0, 30.9, 30.2, 28.2, 28.2, 23.2, 22.0, 21.8,
21.3, 13.4. HRMS: calcd for C42H48O2 584.3654, found 584.3648.
Anal. Calcd: C, 86.26; H, 8.27. Found: C, 86.19; H, 8.25.
NanoPilgrim (15). In a small vial, NanoKid (13) (136 mg,
0.251 mmol), p-toluenesulfonic acid monohydrate (3 mg, 0.013
mmol), 1,2-dimethyl-1,2-cyclobutanediol (320 mg, 2.759 mmol),
and MgSO4 (60 mg, 0.501 mmol) were subjected to microwave
irradiation for 13 min. The reaction mixture was purified flash
chromatography (silica gel, hexanes/CH2Cl2 60/40) to afford
38 mg (25% yield, 33% yield based on recovered starting
material) of the title compound as a sticky yellow oil. The
product was inseparable from a small amount of the aldehyde.
The product was obtained as an inseparable 45:55 mixture of
diastereomers. 1H NMR (400 MHz, CDCl3):
7.76 (s, 0.45 H),
7.60 (s, 0.55 H), 7.53 (s, 0.55 H), 7.52 (s, 0.45 H), 7.46 (d, J =
1.4 Hz, 4 H), 7.37 (t, J = 1.4 Hz, 2 H), 6.47 (s, 0.55 H), 6.21 (s,
0.45 H), 2.38 (t, J = 7.0 Hz, 8 H), 2.21 (pseudo pent, J = 5.4
Hz, 4 H), 2.00 (pseudo q, J = 5.4 Hz, 2 H), 1.85 (pseudo q, J =
5.4 Hz, 2 H), 1.61 (sext, J = 7.2 Hz, 8 H), 1.39-1.35 (m, 36
H), 1.05 (m, 24 H). HRMS: calcd for C43H48O2 596.3654, found
596.3649.
NanoGreenBeret (16). In a small vial, NanoKid (13) (0.206
g, 0.380 mmol), p-toluenesulfonic acid monohydrate (0.014 g,
0.075 mmol), 1,2-propanediol (2.78 mL, 37.69 mmol), and
MgSO4 (0.500 g, 4.15 mmol) were subjected to microwave
irradiation for 1 min. The reaction mixture was then diluted
with a saturated solution of NaHCO3 and extracted with ether.
The combined organic phases were dried over MgSO4, filtered,
and evaporated in vacuo. Purification by flash chromatography
(silica gel, hexanes/CH2Cl2 60/40) afforded 179 mg (85% yield)
of the title compound as a sticky yellow solid. The product was
obtained as an inseparable 1:1 mixture of diastereoisomers.
IR (KBr): 2966, 2231, 1585, 1532, 1451, 1380 cm-1. 1H NMR
(400 MHz, CDCl3):
7.63 (s, 0.5 H), 7.60 (s, 0.5 H), 7.53 (s, 2
H), 7.47 (t, J = 1.2 Hz, 4 H), 7.38 (t, J = 1.2 Hz, 2 H), 6.23 (s,
0.5 H), 6.13 (s, 0.5 H), 4.45 (pseudo sext, J = 6.1 Hz, 0.5 H),
4.35 (m, 1 H), 4.13 (dd, J = 6.5, 7.4 Hz, 0.5 H), 3.63 (t, J = 7.4
Hz, 0.5 H), 3.58 (dd, J = 6.5, 7.4 Hz, 0.5 H), 2.38 (t, J = 7.0
Hz, 8 H), 1.60 (sext, J = 7.3 Hz, 8 H), 1.42 (d, J = 6.1 Hz, 3
H), 1.372 (s, 4.5 H), 1.366 (s, 4.5 H), 1.36 (s, 3 H), 1.34 (s, 4.5
H), 1.33 (s, 4.5 H), 1.05 (t, J = 7.3 Hz, 6 H). 13C NMR (100
MHz, CDCl3):
138.9, 138.3, 135.3, 134.2, 133.5, 129.6, 129.4,
125.7, 125.7, 125.7, 125.5, 124.5, 123.5, 122.4, 122.2, 105.0,
104.9, 104.1, 101.4, 100.6, 92.0, 91.3, 88.4, 88.4, 79.4, 77.8, 75.6,
75.5, 73.7, 72.5, 72.1, 71.3, 31.0, 30.8, 28.2, 22.0, 21.3, 18.4,
18.2, 13.4. HRMS: calcd for C40H44O2 556.3341, found 556.3341.
Anal. Calcd: C, 86.29; H, 7.97. Found: C, 86.16; H, 8.03.
NanoJester (17). In a small vial, NanoKid (13) (0.254 g,
0.468 mmol), p-toluenesulfonic acid monohydrate (0.003 g,
0.014 mmol), cis-cyclopentanediol (0.974 g, 9.54 mmol), and
MgSO4 (0.113 g, 0.936 mmol) were subjected to microwave
irradiation for 6.5 min. The reaction mixture was then diluted
with a saturated solution of NaHCO3 and extracted with ether.
The combined organic phases were dried over MgSO4, filtered,
and evaporated in vacuo. Purification by flash chromatography
(silica gel, hexanes/CH2Cl2 60/40) afforded 257 mg (94% yield)
of the title compound as a sticky yellow oil. The product was
obtained as an inseparable 10:3 mixture of diastereomers. IR
(NaCl, CHCl3): 2965, 2869, 2231, 1581, 1491, 1457, 1403, 1362
cm-1. 1H NMR (400 MHz, CDCl3): (major)
7.69 (s, 1 H), 7.52
(s, 1 H), 7.43 (d, J = 1.5 Hz, 2 H), 7.39 (t, J = 1.5 Hz, 1 H),
5.94 (s, 1 H), 4.65 (d, J = 3.5 Hz, 2 H), 2.38 (t, J = 7.0 Hz,
4 H), 2.10 (m, 2 H), 2.07 (m, 2 H), 1.62 (sext, J = 7.2 Hz, 4 H),
1.49 (m, 2 H), 1.39 (s, 9 H), 1.34 (s, 9 H), 1.05 (t, J = 7.4 Hz,
6 H). 13C NMR (100 MHz, CDCl3): (major)
137.2, 134.9,
134.1, 133.4, 129.3, 125.7, 125.7, 124.5, 123.4, 122.4, 104.7,
104.0, 101.6, 100.0, 91.2, 88.4, 81.9, 79.3, 77.8, 75.3, 33.0, 30.9,
30.7, 30.7, 28.14, 28.10, 22.0, 21.2, 13.3. HRMS: calcd for
C42H46O2 582.3498, found 582.3491. Anal. Calcd: C, 86.55; H,
7.96. Found: C, 86.74; H, 7.88.
NanoMonarch (18). In a small vial, NanoKid (13) (99 mg,
0.182 mmol), p-toluenesulfonic acid monohydrate (0.004 g,
0.021 mmol), cis-1,2-cycloheptanediol (0.109 g, 0.838 mmol),
and MgSO4 (0.044 g, 0.365 mmol) were subjected to microwave
irradiation for 10 min. The reaction mixture was then diluted
with a saturated solution of NaHCO3 and extracted with ether.
The combined organic phases were dried over MgSO4, filtered,
and evaporated in vacuo. Purification by flash chromatography
(silica gel, hexanes/CH2Cl2 60/40) afforded 97 mg (87% yield)
of the title compound as a yellow sticky oil. The product was
obtained as a 10:3 ratio of diastereomers. IR (NaCl, CHCl3):
2967, 2932, 2867, 2231, 1581, 1454, 1411, 1361 cm-1. 1H NMR
(400 MHz, CDCl3): (major)
7.67 (s, 1 H), 7.51 (s, 1 H), 7.47
(d, J = 1.5 Hz, 2 H), 7.38 (t, J = 1.5 Hz, 1 H), 6.08 (s, 1 H),
4.31 (m, 2 H), 2.38 (t, J = 7.0 Hz, 4 H), 2.04-1.64 (m, 8 H),
1.60 (sext, J = 7.2 Hz, 4 H), 1.37 (s, 9 H), 1.34 (s, 9 H), 1.32
(m, 2 H), 1.05 (t, J = 7.2 Hz, 6 H). 13C NMR (100 MHz,
CDCl3):
137.7, 135.1, 134.2, 133.5, 129.7, 125.8, 125.7, 124.5,
123.5, 122.5, 104.7, 104.0, 99.8, 91.2, 88.5, 80.2, 79.9, 79.4, 77.9,
75.5, 31.0, 30.8, 30.4, 28.23, 28.20, 24.2, 22.0, 21.3, 13.4.
HRMS: calcd for C44H50O2 610.3811, found 610.3811. Anal.
Calcd: C, 86.51; H, 8.25. Found: C, 86.50; H, 8.29.
NanoTexan (19). In a small vial, NanoKid (13) (59 mg,
0.109 mmol), p-toluenesulfonic acid monohydrate (few crystals), 1,2-dimethyl-1,2-cyclopentanediol (130 mg, 1.0 mmol),
and MgSO4 (50 mg, 0.748 mmol) were subjected to microwave
irradiation for 9 min. The reaction mixture was purified flash
chromatography (silica gel, hexanes/CH2Cl2 60/40) to afford
34 mg (24% yield, 58% yield based on recovered starting
material) of the title compound as a sticky yellow oil. The
desired product was inseparable from a small amount of the
parent aldehyde. The product was obtained as an inseparable
1:3.2 mixture of diastereomers. 1H NMR (400 MHz, CDCl3):
(major)
7.70 (s, 1 H), 7.51 (s, 1 H), 7.46 (d, J = 1.5 Hz, 2 H),
7.37 (t, J = 1.5 Hz, 1 H), 6.06 (s, 1 H), 2.38 (t, J = 7.0 Hz, 4
H), 2.16 (m, 2 H), 1.64 (sext, J = 7.0 Hz, 4 H), 1.39-1.34 (m,
28 H), 1.06 (t, J = 7.3 Hz, 6 H). HMRS: calcd for C44H50O2
610.3811, found 610.3811.
NanoScholar (20). In a small vial, NanoKid (13) (92 mg,
0.170 mmol), p-toluenesulfonic acid monohydrate (few crystals), 4-methyl-cis-1,2-cyclohexanediol (443 mg, 3.408 mmol),
and MgSO4 (41 mg, 0.341 mmol) were subjected to microwave
irradiation for 16 min. The reaction mixture was purified flash
chromatography (silica gel, hexanes/CH2Cl2 60/40) to afford
93 mg (90% yield) of the title compound as a sticky yellow oil.
The product was obtained as an inseparable 17:12:12:9 mixture
of diastereomers. IR (NaCl, CHCl3): 2967, 2869, 2232, 1582,
1456, 1362, 1265, 1103 cm-1. 1H NMR (400 MHz, CDCl3): (four
isomers)
7.67 (s, 1 H), 7.66 (s, 1 H), 7.56 (s, 1 H), 7.55 (s, 1
H), 7.52 (m, 4 H), 7.47 (m, 8 H), 7.38 (m, 4 H), 6.43 (s, 1 H),
6.42 (s, 1 H), 6.16 (s, 1 H), 6.15 (s, 1 H), 4.30 (m, 8 H), 2.38 (t,
J = 7.0 Hz, 16 H), 2.28 (m, 4 H), 2.0-1.7 (m, 12 H), 1.63 (sext,
J = 7.0 Hz, 16 H), 1.55-1.45 (m, 4 H), 1.37-1.32 (m, 72 H),
1.30-1.15 (m, 8 H), 1.05 (t, J = 7.3 Hz, 24 H), 0.95 (m, 12 H).
13C NMR (100 MHz, CDCl3): (four isomers)
140.9, 140.8,
139.2, 139.1, 135.4, 135.4, 134.4, 133.8, 129.6, 129.4, 129.2,
125.9, 125.8, 125.8, 125.7, 125.4, 124.8, 123.7, 122.8, 122.2,
105.5, 105.4, 105.3, 104.3, 104.2, 101.1, 99.9, 99.8, 92.1, 92.0,
91.5, 88.7, 79.6, 78.2, 77.4, 76.7, 76.1, 76.0, 75.8, 75.8, 75.5,
74.8, 74.6, 74.3, 73.4, 38.9, 36.0, 35.8, 35.5, 34.9, 31.8, 31.2,
31.1, 31.0, 30.6, 29.9, 29.4, 29.3, 29.1, 28.6, 28.5, 27.0, 26.9,
26.7, 26.5, 26.5, 25.5, 22.9, 22.4, 22.4, 22.3, 22.0, 21.8, 21.5,
14.3, 13.7. HMRS: calcd for C44H50O2 610.3811, found 610.3812.
Anal. Calcd: C, 86.51; H, 8.25. Found: C, 86.36; H, 8.27.
NanoBaker (21). In a small vial, NanoKid (13) (128 mg,
0.236 mmol), p-toluenesulfonic acid monohydrate (few crystals), cis-1,2-cyclohexanediol (411 mg, 3.54 mmol), and MgSO4
(116 mg, 0.964 mmol) were subjected to microwave irradiation
for 10 min. The reaction mixture was purified flash chromatography (silica gel, hex/CH2Cl2 60/40) to afford 118 mg (84%
yield) of the title compound as a sticky yellow oil. The product
was obtained as an inseparable 1:1.63 mixture of diastereomers. IR (NaCl, CHCl3): 2969, 2869, 2253, 1582, 1456, 1363,
1266, 1153 cm-1. 1H NMR (400 MHz, CDCl3): (major)
7.68
(s, 1 H), 7.52 (s, 1 H), 7.46 (m, 2 H), 7.37 (m, 1 H), 6.15 (s, 1
H), 4.30 (m, 1 H), 4.20 (m, 1 H), 2.38 (t, J = 6.9 Hz, 4 H),
1.87-1.70 (m, 4 H), 1.69-1.58 (m, 8 H), 1.37 (s, 9 H), 1.36 (s,
9 H), 1.05 (t, J = 7.3 Hz, 6 H). 13C NMR (100 MHz, CDCl3)
(two isomers)
140.7, 138.9, 135.20, 135.17, 134.2, 133.6,
129.2, 128.94, 125.7, 125.6, 125.6, 125.2, 124.5, 123.5, 122.6,
122.0, 105.3, 105.1, 104.1, 104.0, 100.7, 99.6, 91.9, 91.8, 91.2,
88.5, 79.4, 78.0, 77.2, 75.7, 75.6, 75.1, 74.6, 31.0, 30.8, 28.3,
28.2, 28.3, 27.1, 22.1, 21.3, 21.1, 20.7, 13.5. HMRS: calcd for
C43H48O2 596.3654, found 596.3654.
NanoChef (22). To 100 mL round-bottom flask equipped
with a condenser were added NanoKid (223 mg, 0.411 mmol),
catechol (0.998 g, 9.063 mmol), and MgSO4 (0.498 g, 4.137
mmol). The atmosphere was removed and replaced with
nitrogen. To the flask were added trimethylsilyl chloride (0.26
mL, 2.05 mmol) and freshly distilled CH2Cl2. The mixture was
allowed to stir at reflux for 42 h. A 5% solution of NaHCO3
was added, and the reaction mixture was extracted with CH2Cl2. The combined organic phases were dried over MgSO4 and
filtered, and the solvent was evaporated in vacuo. Purification
by flash chromatography (silica gel, hexanes/CH2Cl2 60/40)
afforded 23 mg (9% yield, 20% recovered) of the title product
as a white solid. Mp: 117-124
C. IR (KBr): 2966, 2929, 2900,
2867, 2225, 1580, 1481, 1350, 1230, 1022 cm-1. 1H NMR (400
MHz, CDCl3):
7.63 (s, 1 H), 7.60 (s, 1 H), 7.47 (d, J = 1.5
Hz, 2 H), 7.40 (t, J = 1.5 Hz, 1 H), 7.22 (s, 1 H), 6.89 (m, 4 H),
2.39 (t, J = 7.0 Hz, 4 H), 1.62 (sext, J = 7.2 Hz, 4 H), 1.35 (s,
9 H), 1.29 (s, 9 H), 1.05 (t, J = 7.2 Hz, 6 H). 13C NMR (100
MHz, CDCl3):
147.6, 136.2, 135.7, 134.4, 133.6, 129.8, 126.8,
125.9, 124.6, 123.3, 122.2, 121.7, 108.6, 108.0, 106.0, 104.9,
92.7, 91.4, 88.1, 79.4, 75.0, 30.9, 30.7, 28.3, 22.1, 21.3, 13.5.
HRMS: calcd for C43H42O2 590.3185, found 590.3178.
Mixture of NanoPutians 14-21. In a small vial, NanoKid (163 mg, 0.30 mmol) was mixed with cis-1,2-dimethyl-1,2-cyclopentanediol (78 mg, 0.60 mmol), cis-cyclopentane-1,2-diol (61 mg, 0.60 mmol), cis-1,2-dimethylcyclobutane-1,2-diol (69 mg, 0.60 mmol), cis-cycloheptane-1,2-diol (78 mg, 0.60 mmol), 4-methyl-cis-1,2-cyclohexanediol (78 mg, 0.60 mmol), cis-1,2-cyclohexanediol (69 mg, 0.60 mmol), 1,2-propanediol (0.044 mL, 0.60 mmol), 2,2-dimethyl-1,3-propanediol (62 mg, 0.60 mmol), p-toluenesulfonic acid monohydrate (few crystals), and MgSO4 (130 mg, 1.08 mmol). The reaction mixture was subjected to microwave irradiation for 4 min. The crude reaction mixture was purified by flash chromatography (silica gel, hexanes/CH2Cl2 66/33), which afforded 161 mg of a mixture of all the NanoPutians 14-21. This was confirmed by mass spectrometric analysis of the reaction mixture where the mass of each NanoPutian was detected. However, since a few of the figures have the same molecular weight, further confirmation was obtained using 1H NMR peak matching of the mixture against the individual NanoPutian spectra referenced above.
3,5-(1'-Butynyl)-1-(trimethylsilylethynyl)benzene (23).
See the Pd/Cu general procedure (Supporting Information). A
solution of 3,5-dibromo(trimethylsilylethynyl)benzene (10)
(1.91 g, 5.75 mmol), bis(triphenylphosphine)palladium(II)
dichloride (0.202 g, 0.288 mmol), copper(I) iodide (0.109 g,
0.575 mmol) in THF (30 mL), and Et3N (15 mL) was cooled to
-70
C. To this solution was added cold (-70
C) 1-butyne (3
mL, 37.63 mmol). The mixture was allowed to warm to room
temperature and heated to 74
C for 2 d. After the mixture
was checked by TLC, more of the cold 1-butyne (2.4 mL, 30.10
mmol) was added. The reaction mixture was allowed to stir
for another 2 d. Purification by flash chromatography (silica
gel, hexanes) afforded 1.34 g (84% yield) of the title compound
as a clear liquid. IR (NaCl): 2976, 2938, 2241, 2161, 1581,
1455, 1414, 1316, 1250 cm-1. 1H NMR (400 MHz, CDCl3):
7.39 (d, J = 1.5 Hz, 2 H), 7.35 (t, J = 1.5 Hz, 1 H), 2.40 (q,
J = 7.5 Hz, 4 H), 1.22 (t, J = 7.5 Hz, 6 H), 0.24 (s, 9 H). 13C
NMR (100 MHz, CDCl3):
134.4, 133.8, 124.4, 123.4, 103.7,
94.9, 92.6, 78.5, 13.8, 13.0, -0.2. HRMS: calcd for C19H22Si
278.1491, found 278.1486.
3,5-(1'-Butynyl)-1-ethynylbenzene (24). See the general
alkyne deprotection procedure (Supporting Information). To
a solution of 23 (0.450 g, 1.616 mmol) in MeOH (20 mL) and
CH2Cl2 (20 mL) was added K2CO3 (2.21 g, 15.98 mmol). The
solution was stirred at 23
C for 2 h. The reaction afforded
0.65 g (99% yield) of the title compound as a yellow oil. The
compound was too unstable to attain its complete characterization data, and it was immediately used in the next step. IR
(KBr): 3301, 2978, 2937, 2240, 1582, 1454, 1316 cm-1. 1H NMR
(400 MHz, CDCl3):
7.40 (m, 3 H), 3.05 (s, 1 H), 2.40 (q, J =
7.5 Hz, 4 H), 1.22 (t, J = 7.5 Hz, 6 H). 13C NMR (100 MHz,
CDCl3):
135.0, 134.2, 124.7, 122.6, 93.1, 82.6, 78.6, 77.9, 14.0,
13.3. HRMS: calcd for C16H14 206.1096, found 206.1094.
NanoToddler (25). See the Pd/Cu general procedure (Supporting Information). To a solution of 5 (0.49 g, 1.123 mmol),
bis(triphenylphosphine)palladium(II) dichloride (0.039 g, 0.056
mmol), copper(I) iodide (0.021 g, 0.112 mmol) in THF (20 mL)
were added Et3N (20 mL) and 24 (0.253 g, 1.228 mmol) in THF
(20 mL) via a cannula. The mixture was stirred at 80
C for
42 h. Purification by flash chromatography (silica gel, hexanes/CH2Cl2 60/40) afforded 0.45 g (78% yield) of the title compound
as a yellow oil. IR (NaCl): 2970, 2895, 2236, 1581, 1474, 1455,
1397, 1316, 1266, 1202, 1107 cm-1. 1H NMR (400 MHz,
CDCl3):
7.59 (s, 1 H), 7.53 (s, 1 H), 7.46 (d, J = 1.4 Hz, 2 H),
7.38 (t, J = 1.4 Hz, 1 H), 6.11 (s, 1 H), 4.18 (m, 2 H), 4.05 (m,
2 H), 2.40 (q, J = 7.5 Hz, 4 H), 1.37 (s, 9 H), 1.34 (s, 9 H), 1.23
(t, J = 7.5 Hz, 6 H). 13C NMR (100 MHz, CDCl3):
138.4,
135.4, 134.2, 133.5, 129.5, 125.7, 125.6, 124.5, 123.4, 122.3,
105.0, 104.2, 101.4, 92.7, 92.0, 88.4, 78.5, 77.7, 75.5, 65.4, 31.0,
30.8, 28.23, 28.22, 13.8, 13.0. HRMS: calcd for C37H38O2
514.2872, found 514.2869. Anal. Calcd: C, 86.34; H, 7.44.
Found: C, 86.24; H, 7.58.
3,5-(4'-Thiolacetyl-1'-butynyl)-1-(trimethylsilylethynyl)benzene (28). See the Pd/Cu general procedure (Supporting
Information). To a solution of bis(triphenylphosphine)palladium(II) dichloride (0.438 g, 0.625 mmol), copper(I) iodide
(0.238 g, 1.25 mmol) in THF (15 mL) were added Et3N (20
mL) a solution of 10 (2.07 g, 6.25 mmol) in THF (15 mL) and
a solution of 27 (1.68 g, 13.12 mmol) in THF (20 mL) via a
cannula. The mixture was stirred at 75
C for 4 d. The solvent
was evaporated in vacuo. The residue was diluted with NH4Cl and extracted with Et2O. The combined organic phases were
dried over MgSO4, filtered, and the solvent evaporated in
vacuo. Purification by flash chromatography (silica gel, CH2Cl2) afforded a mixture of starting material, mono- and
decoupled products. This mixture was resubmitted to the same
amount of reagents and then heated to 80
C for 4 d.
Purification by flash chromatography (silica gel, hexanes/CH2Cl2 50/50) afforded 0.531 g (20% yield) of the title compound
as a yellow sticky liquid. IR (KBr): 2959, 2248, 2156, 1693,
1581, 1414, 1354, 1250, 1133 cm-1. 1H NMR (400 MHz,
CDCl3):
7.40 (d, J = 1.5 Hz, 2 H), 7.35 (t, J = 1.5 Hz, 1 H),
3.09 (t, J = 7.0 Hz, 4 H), 2.68 (t, J = 7.0 Hz, 4 H), 2.36 (s, 3
H), 0.24 (s, 9 H). 13C NMR (100 MHz, CDCl3):
195.5, 134.6,
134.4, 124.0, 123.7, 103.6, 95.6, 88.9, 80.5, 30.8, 28.5, 20.6, 0.0.
HRMS: calcd for C23H26O2S2Si 426.1144, found 426.1146.
3,5-(4'-Thiolacetyl-1'-butynyl)-1-(ethynyl)benzene (29).
To a solution of 27 (0.531 g, 1.25 mmol) in THF (5 mL) were
added a mixture of acetic anhydride (0.47 mL, 4.99 mmol) and
acetic acid (0.286 mL, 4.94 mmol) and TBAF (1 M, 2.99 mmol).
This solution was stirred at rt for 35 min. The reaction mixture
was diluted with water and extracted with ether. The combined organic phases were dried over MgSO4 and filtered, and
the solvent was evaporated in vacuo. Purification by flash
chromatography (silica gel, hexanes/CH2Cl2 30/70) afforded
0.379 g (86% yield) of the title compound as a yellow oil. IR
(KBr): 3304, 2253, 1690, 1583, 1434, 1355, 1133 cm-1. 1H NMR
(400 MHz, CDCl3):
7.42 (d, J = 1.5 Hz, 2 H), 7.40 (t, J = 1.5
Hz, 1 H), 3.11(t, J = 7.0 Hz, 4 H), 3.07 (s, 1 H), 2.68 (t, J = 7.0
Hz, 4 H), 2.37 (s, 3 H). 13C NMR (100 MHz, CDCl3):
195.6,
135.1, 134.6, 124.2, 122.8, 89.2, 82.3, 80.4, 78.3, 30.9, 28.5, 20.7.
HRMS: calcd for C20H18O2S2 354.0748, found 354.0748.
NanoKid with Thiolacetate Feet (30). See the Pd/Cu
general procedure (Supporting Information). To a solution of
the free alkyne 29 (0.379 g, 1.070 mmol), 5 (0.467 g, 1.017
mmol), bis(triphenylphosphine)palladium(II) dichloride (0.038
g, 0.0535 mmol), and copper(I) iodide (0.020 g, 0.107 mmol) in
THF (20 mL) was added Et3N (10 mL). This solution was
stirred at rt for 20 h. Purification by flash chromatography
(silica gel, CH2Cl2) afforded 0.224 g (31% yield) of the title
compound as a sticky yellow oil. IR (KBr, CDCl3): 2971, 2898,
2253, 1690, 1582, 1474, 1456, 1400, 1359, 1134, 1107 cm-1.
1H NMR (400 MHz, CDCl3):
7.58 (s, 1 H), 7.52 (s, 1 H), 7.47
(d, J = 1.5 Hz, 2 H), 7.38 (t, J = 1.5 Hz, 1 H), 6.11 (s, 1 H),
4.19 (m, 2 H), 4.05 (m, 2 H), 3.11 (t, J = 7.0 Hz, 4 H), 2.69 (t,
J = 7.0 Hz, 4 H), 2.37 (s, 6 H), 1.36 (s, 9 H), 1.33 (s, 9 H). 13C
NMR (100 MHz, CDCl3):
195.6, 138.7, 135.7, 134.6, 134.2,
129.7, 125.9, 125.7, 124.2, 123.9, 122.6, 105.3, 104.5, 101.6,
91.9, 89.0, 88.9, 80.5, 78.0, 75.7, 65.7, 53.6, 31.2, 31.0, 30.8,
28.5, 28.49, 28.47, 20.6. HRMS: calcd for C41H42O4S2 662.2525,
found 662.2525.
3,6-Dibromo-2,4-diiodoaniline (31). In a 500 mL round-bottom flask equipped with an addition funnel were stirred
2,5-dibromoaniline (9.52 g, 37.96 mmol), sodium acetate (6.85
g, 83.50 mmol), and acetic acid (60 mL) at rt. To this
suspension was slowly added ICl (4.26 mL, 83.50 mmol) in
acetic acid (15 mL). The mixture was heated to 80
C for 5 h,
diluted with water, and stirred for an additional 1 h after
which it was allowed to stand overnight. The suspension was
filtered and washed with a saturated solution of sodium
bisulfite and water. After drying, it afforded a brown solid.
NMR showed a mixture of product and mono-iodinated byproduct in a 1:0.3 ratio. The mixture was mixed with sodium
acetate (6.85 g, 83.50 mmol) and acetic acid (80 mL). To this
suspension was added slowly ICl (2.9 mL, 56.94 mmol) in acetic
acid (20 mL). The mixture was heated to 80
C for 18 h, diluted
with water, and stirred for an additional 1 h after which it
was allowed to stand overnight. The suspension was filtered
and washed with a saturated solution of sodium bisulfite and
water. After drying, it afforded a brown solid (16.80 g, 88%
yield). Mp: 136-148
C. IR (KBr): 3489, 2925, 2854, 1597
cm-1. 1H NMR (400 MHz, CDCl3):
7.94 (s, 1 H), 5.65 (br s,
2 H). 13C NMR (100 MHz, CDCl3):
147.3, 141.1, 135.6, 105.3,
90.2, 82.9 ppm. HRMS: calcd for C6H3Br2I2N 500.6722, found
500.6721.
2,5-Dibromo-1,3,diiodobenzene (32). Isoamylnitrite (5.4
mL, 40.1 mmol) and DMF (20 mL) were heated to 65
C. To
this mixture was slowly added 31 (16.80 g, 33.42 mmol) in
DMF (80 mL). The reaction mixture was stirred for 24 h,
diluted with HCl (1 M, 60 mL), and extracted with CHCl3. The
combined organic phases were dried over MgSO4, filtered, and
evaporated in vacuo. The NMR of the crude product showed a
mixture of starting material and product. The crude was
subjected to the same reaction for 2 d at 70
C. The reaction
mixture was diluted with HCl (1 M, 60 mL) and water. The
light brown solid was filtered and recrystallized from ethanol,
and after purification by flash chromatography (silica gel,
hexanes), it afforded 7.07 g (43% yield) of the title compound
as a white solid. Mp: 126-130
C. IR (KBr): 3071, 1531, 1517,
1388, 1370, 1351 cm-1. 1H NMR (400 MHz, CDCl3):
7.98 (s,
2 H). 13C NMR (100 MHz, CDCl3):
142.3, 135.5, 121.8, 100.4
ppm. HRMS: calcd for C6H2Br2I2 485.6613, found 485.6612.
2,6-Bis(3',3'-dimethylbutynyl)-1,4-dibromobenzene (33).
See the Pd/Cu general procedure (Supporting Information). To
a solution of 32 (1.78 g, 3.650 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.256 g, 0.365 mmol), and copper(I)
iodide (0.139 g, 0.730 mmol) in THF (50 mL) were added Et3N
(15 mL) and 3,3-dimethyl-1-butyne (0.99 mL, 8.03 mmol). The
mixture was stirred at rt for 1 d. Purification by flash
chromatography (silica gel, hexanes) afforded 1.08 g (75%
yield) of the title compound as a white solid. Mp: 124-138
C. IR (KBr): 2969, 2927, 2899, 2866, 2226, 1558, 1544, 1393,
1362, 1272, 1224, 1202 cm-1. 1H NMR (400 MHz, CDCl3):
7.42 (s, 2 H), 1.34 (s, 18 H). 13C NMR (100 MHz, CDCl3):
134.3, 128.4, 127.8, 119.8, 105.1, 86.5, 30.9, 28.5 ppm.
HRMS: calcd for C18H20Br2 393.9932, found 393.9938.
4-Bromo-2,6-(3',3'-dimethylbutynyl)benzaldehyde (34)
and 4-Bromo-3,5-(3',3'-dimethylbutynyl)benzaldehyde
(35). To 33 (4.47 g, 11.28 mmol) in THF (50 mL) cooled to -78
C under nitrogen was dropwise added t-BuLi (1.7 M, 13.94
mL). The reaction mixture was allowed to stir at -78
C for
30 min. To this mixture was added DMF (1.75 mL, 22.56
mmol) predried over molecular sieves. The reaction mixture
was allowed to warm to rt overnight. It was then diluted with
water and extracted with Et2O. The combined organic phases
were washed with brine, dried over MgSO4, filtered, and
evaporated. Purification by flash chromatography (silica gel,
hexanes/CH2Cl2 75/25) afforded 1.47 g (38% yield) of 34 and
1.45 g (37% yield) of 35 as white solids. Less polar product
34. Mp: 97-100
C. IR (KBr): 2968, 2924, 2898, 2864, 2758,
2230, 1706, 1554, 1475, 1454, 1390, 1362, 1264 cm-1. 1H NMR
(400 MHz, CDCl3):
10.54 (s, 1 H), 7.54 (s, 2 H), 1.35 (s, 18
H). 13C NMR (100 MHz, CDCl3):
190.5, 135.7, 135.2, 127.7,
126.8, 107.2, 75.5, 30.8, 28.6 ppm. HRMS: calcd for C19H21BrO 344.0776, found 344.0779. More polar product 35. Mp:
102-114
C. IR (KBr): 2969, 2928, 2901, 2867, 2816, 1781,
2704, 2231, 1707, 1569, 1456, 1426, 1379, 1361, 1263 cm-1.
1H NMR (400 MHz, CDCl3):
9.90 (s, 1 H), 7.76 (s, 2 H), 1.36
(s, 18 H). 13C NMR (100 MHz, CDCl3):
190.6, 135.7, 135.8,
132.0, 128.2, 105.5, 77.7, 30.9, 28.6 ppm. HRMS: calcd for
C19H21BrO 344.0776, found 344.0774.
3,5-Bis(3',3'-dimethylbutynyl)-4-(1' ',3' '-dioxolane)-1-bromobenzene (36). To a round-bottom flask equipped with a
Dean-Stark trap for azeotropic removal of the water were
added 34 (1.52 g, 4.40 mmol), ethylene glycol (1.47 mL, 26.41
mmol), p-toluenesulfonic acid (0.042 g, 0.22 mmol), and toluene
(100 mL). The reaction mixture was heated to reflux for 1 d.
It was then diluted with aq K2CO3. The solution was extracted
with ether. The combined organic phases were dried over
MgSO4, filtered, and evaporated. Purification by flash chromatography (silica gel, hexanes/CH2Cl2 60/40) afforded 1.22 g
(71% yield) of the title compound as a white solid. Mp: 96-98
C. IR (KBr): 2966, 2926, 2891, 2221, 1560, 1411, 1383, 1220,
1256, 1102, 1080 cm-1. 1H NMR (400 MHz, CDCl3):
7.47 (s,
2 H), 6.31 (s, 1 H), 4.29 (m, 2 H), 4.06 (m, 4 H), 1.32 (s, 18 H).
13C NMR (100 MHz, CDCl3):
137.4, 135.8, 126.1, 122.2,
104.7, 102.2, 76.1, 66.4, 31.1, 28.4 ppm. HRMS: calcd for
C21H25BrO2 388.1038, found 388.1030.
3,5-Dibromobenzadehyde (37). To 3,5-dibromoiodobenzene (6.037 g, 16.686 mmol) in THF (50 mL) cooled to -78
C
under nitrogen was dropwise added n-BuLi (2.39 M, 7.68 mL).
The reaction mixture was allowed to stir at -78
C for 30 min.
To this mixture was added DMF (1.55 mL, 20.023 mmol)
predried over molecular sieves. The reaction mixture was
allowed to warm to rt overnight. It was then diluted with water
and extracted with Et2O. The combined organic phases were
washed with brine, dried over MgSO4, filtered, and evaporated.
Purification by flash chromatography (silica gel, hexanes/CH2Cl2 50/50) afforded 1.25 g (28% yield) of the title compound as
a white solid. Mp: 86-90
C. IR (KBr): 3064, 2844, 1697,
1556, 1384, 1190 cm-1. 1H NMR (400 MHz, CDCl3):
9.91 (s,
1 H), 7.95 (d, J = 1.6 Hz, 2 H), 7.92 (t, J = 1.6 Hz, 1 H). 13C
NMR (100 MHz, CDCl3):
189.4, 139.8, 139.1, 131.4, 124.2
ppm. HRMS: calcd for C7H4Br2O 263.8609, found 263.8602.
3,5-Bis(pentynyl)benzaldehyde (38). See the Pd/Cu general procedure (Supporting Information). To a solution of 37
(2.60 g, 9.855 mmol), bis(triphenylphosphine)palladium(II)
dichloride (0.691 g, 0.985 mmol), and copper(I) iodide (0.375
g, 1.971 mmol) in THF (50 mL) were added Et3N (20 mL) and
1-pentyne (5.83 mL, 59.13 mmol). The mixture was stirred at
80
C for 2 d. Purification by flash chromatography (silica gel,
hexanes/CH2Cl2 50/50) afforded 2.19 g (93% yield) of the title
compound as a yellow liquid. IR (KBr): 2965, 2934, 2873, 2234,
1702, 1591, 1448, 1384, 1339, 1153 cm-1. 1H NMR (400 MHz,
CDCl3):
9.93 (s, 1 H), 7.77 (d, J = 1.5 Hz, 2 H), 7.64 (s, 1 H),
2.40 (t, J = 4.3 Hz, 4 H), 1.64 (sext, J = 2.8 Hz, 4 h), 1.06 (t,
J = 7.4 Hz, 6 H). 13C NMR (100 MHz, CDCl3):
191.4, 140.0,
136.6, 131.6, 125.6, 92.7, 79.2, 22.2, 21.6, 13.7 ppm. HRMS:
calcd for C17H18O 238.1358, found 238.1359.
39. To a solution of 36 (1.747 g, 4.487 mmol) in THF (25
mL) at -78
C was dropwise added n-BuLi (2.39 M, 2.44 mL).
The reaction mixture was stirred for 30 min. Then 38 (1.176
g, 4.936 mmol) was added. The reaction mixture was allowed
to warm to rt. It was then diluted with aq NaOH and extracted
with Et2O. The combined organic phases were dried over
MgSO4, filtered, and evaporated. Purification by flash chromatography (silica gel, CH2Cl2) afforded 1.97 g (78% yield) of
the title compound as a white sticky solid. Mp: 64-80
C. IR
(KBr): 3446, 2966, 2931, 2899, 2870, 2228, 1589, 1456, 1390,
1362, 1259, 1202, 1088 cm-1. 1H NMR (400 MHz, CDCl3):
7.34 (t, J = 1.5 Hz, 1 H), 7.30 (s, 2 H), 7.24 (d, J = 1.3 Hz, 2
H), 6.36 (s, 1 H), 5.62 (d, J = 2.7 Hz, 1 H), 4.31 (m, 2 H), 4.07
(m, 2 H), 2.37 (t, J = 7.0 Hz, 4 H), 2.18 (d, J = 2.7 Hz, 1 H),
1.62 (sext, J = 7.3 Hz, 4 H), 1.32 (s, 18 H), 1.04 (t, J = 7.3 Hz,
6 H). 13C NMR (100 MHz, CDCl3):
143.8, 143.4, 137.5, 134.2,
131.2, 129.2, 124.6, 103.5, 102.4, 91.2, 80.2, 74.8, 66.3, 31.2,
28.4, 22.3, 21.6, 13.7 ppm. HRMS: calcd for C38H44O3 548.3290,
found 548.3290.
40. Using a three-neck round-bottom flask, 39 (0.195 g,
0.346 mmol) was dissolved in 10 mL of THF. To this solution
were added NaH (71 mg, 1.778 mmol) and a few crystals of
imidazole. After warming to 60
C for 30 min, the solution
turned milky yellow-orange. CS2 (0.13 mL, 2.13 mmol) was
added. After 30 min at 60
C, MeI (0.13 mL, 2.13 mmol) was
added. The milky yellow solution was stirred for another 30
min after which it was quenched with brine and extracted with
CH2Cl2. The combined organic phases were dried over MgSO4,
filtered, and evaporated. Purification by flash chromatography
(silica gel, CH2Cl2/hexanes 33/66 then CH2Cl2) afforded 0.188
g (83% yield) of the title compound as a white sticky solid. IR
(KBr): 2967, 2930, 2900, 2871, 2225, 1590, 1452, 1428, 1362,
1198, 1089, 1059 cm-1. 1H NMR (400 MHz, CDCl3):
7.48 (s,
1 H), 7.38 (t, J = 1.4 Hz, 1 H), 7.29 (s, 2 H), 7.22 (d, J = 1.3
Hz, 2 H), 6.36 (s, 1 H), 4.30 (m, 2 H), 4.06 (m, 2 H), 2.59 (s, 3
H), 2.37 (t, J = 7.0 Hz, 4 H), 1.62 (sext, J = 7.3 Hz, 4 H), 1.32
(s, 18 H), 1.04 (t, J = 7.3 Hz, 6 H). 13C NMR (100 MHz,
CDCl3):
214.7, 139.2, 138.9, 138.4, 134.8, 132.0, 129.7, 124.8,
124.7, 103.9, 102.3, 91.6, 83.3, 79.9, 66.3, 31.1, 28.4, 22.3, 21.6,
13.7. HRMS: calcd for C40H46O3S2 638.2888, found 638.2887.
NanoBalletDancer (41). To a solution of 40 (1.86 mg,
0.2849 mmol) were added a few crystals of 2,2'-azabis(2-methylpropionitrile) in toluene (7 mL) and tri-n-butyltin
hydride (0.196 mL, 0.728 mmol). This solution was heated to
80
C for 3 h. The solvent was evaporated in vacuo, and the
residue was diluted with water and extracted with ether. The
combined organic phases were dried over MgSO4, filtered, and
evaporated. Purification by flash chromatography (silica gel,
CH2Cl2/hex 50/50) afforded 0.103 g of the product mixed with
some starting material. The mixture was resubmitted to the
same amount of reagents for 7 h. The solvent was evaporated
in vacuo, and the residue was diluted with water and extracted
with ether. The combined organic phases were dried over
MgSO4, filtered, and evaporated. Purification by flash chromatography (silica gel, CH2Cl2/hexanes 50/50) afforded 67 mg
(43% yield) of the title compound as a sticky white solid. IR
(KBr): 2969, 2901, 2872, 2252, 1587, 1457, 1391, 1088 cm-1.
1H NMR (400 MHz, CDCl3):
7.30 (s, 1 H), 7.15 (s, 2 H), 7.07
(d, 2 H), 6.36 (s, 1 H), 4.31 (m, 2 H), 4.06 (m, 2 H), 3.79 (s, 2
H), 2.37 (t, J = 7.0 Hz, 4 H), 1.62 (sext, J = 7.3 Hz, 4 H), 1.32
(s, 18 H), 1.04 (t, J = 7.3 Hz, 6 H). 13C NMR (100 MHz,
CDCl3):
140.7, 140.5, 136.5, 134.1, 132.8, 131.3, 124.5, 124.4,
103.2, 102.5, 90.9, 80.3, 66.3, 40.7, 31.2, 28.4, 22.3, 21.6, 13.7.
HRMS: calcd for C38H44O2 532.3341, found 532.3331.
NanoBalletDancer (42). In a small vial, 41 (59 mg, 0.108
mmol), p-toluenesulfonic acid monohydrate (few crystals), 2,2-dimethyl-1,3-propanediol (0.225 mg, 2.158 mmol), and MgSO4
(0.58 mg, 0.482 mmol) were subjected to microwave irradiation
for 8 min. The reaction mixture was then diluted with a
saturated solution of NaHCO3 and all solvent was evaporated
in vacuo. Purification by flash chromatography (silica gel,
hexanes/CH2Cl2 66/33) afforded 59 mg (93% yield) of the title
compound as a white solid. Mp: 146-150
C. IR (KBr): 2963,
2929, 2867, 2838, 2220, 1587, 1457, 1423, 1392, 1364, 1338,
1266, 1099 cm-1. 1H NMR (400 MHz, CDCl3):
7.28 (s, 1 H),
7.15 (s, 2 H), 7.05 (s, 2 H), 6.00 (s, 1 H), 3.81 (d, J = 11.1 Hz,
2 H), 3.77 (s, 2 H), 3.61 (d, J = 11.1 Hz, 2 H), 2.37 (t, J = 7.0
Hz, 4 H), 1.62 (sext, J = 7.3 Hz, 4 H), 1.49 (s, 3 H), 1.34 (s, 18
H), 1.04 (t, J = 7.3 Hz, 6 H), 0.80 (s, 3 H). 13C NMR (100 MHz,
CDCl3):
140.6, 140.1, 136.4, 134.2, 132.7, 131.3, 124.4, 123.7,
102.7, 102.1, 90.8, 80.3, 78.7, 77.8, 40.7, 31.1, 30.7, 28.4, 24.6,
22.3, 22.2, 21.6, 13.7. HRMS: calcd for C41H50O2 574.3811,
found 574.3813. Anal. Calcd: C, 85.67; H, 8.77. Found: C,
85.56; H, 8.78.
2,5-Bis(4-tert-butyldimethylsiloxy-1'-butynyl)-1,4-dibromobenzene (44). See the Pd/Cu general procedure (Supporting Information). To a solution of 2,5-dibromo-1,4-diiodobenzene (19.84 g, 40.687 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.856 g, 1.22 mmol), and copper(I) iodide
(0.620 g, 3.25 mmol) in THF (50 mL) were added Et3N (50
mL) and 43 (17.98 g, 97.65 mmol) in THF (50 mL) via a
cannula. The mixture was stirred at rt for 1 d. Purification by
flash chromatography (silica gel, hexanes/CH2Cl2 60/40) afforded 23.36 g (96% yield) of the title compound as a soft white
solid: IR (KBr in CHCl3) 3309, 3018, 2955, 2931, 2884, 2857,
2400, 2234, 1470, 1387, 1355, 1256, 1216, 1107 cm-1. 1H NMR
(400 MHz, CDCl3):
7.60 (s, 2 H), 3.84 (t, J = 7.1 Hz, 4 H),
2.69 (t, J = 7.1 Hz, 4 H), 0.92 (s, 18 H), 0.10 (s, 12 H). 13C
NMR (100 MHz, CDCl3):
136.4, 126.6, 123.6, 95.2, 79.3, 61.8,
26.1, 24.3, 18.6, -5.0 ppm. HRMS: calcd for C26H40Br2O2Si2
583.0699, found 583.0704.
2,5-Bis(4-tert-butyldimethylsiloxy-1'-butynyl)-4-bromobenzaldehyde (45). To a solution of 44 (10.14 g, 16.895
mmol) in THF (80 mL) cooled to -78
C under nitrogen was
added dropwise n-BuLi (2.53 M, 6.67 mL). The reaction
mixture was allowed to stir at -78
C for 30 min. To this
mixture was added DMF (1.37 mL, 17.74 mmol) predried over
molecular sieves. The reaction mixture was allowed to warm
to rt overnight. It was then diluted with water and extracted
with Et2O. The combined organic phases were washed with
brine, dried over MgSO4, filtered, and evaporated. Purification
by flash chromatography (silica gel, hexanes/CHCl3 20/80)
afforded 5.94 g (64% yield) of the title compound as a white
solid. Mp: 78-82
C. IR (KBr): 2953, 2929, 2886, 2856, 2230,
1695, 1588, 1525, 1471, 1383, 1255, 1107 cm-1. 1H NMR (400
MHz, CDCl3):
10.41 (s, 1 H), 7.90 (s, 1 H), 7.73 (s, 1 H), 3.85
(m, 4 H), 2.70 (m, 4 H), 0.92 (s, 18 H), 0.10 (s, 12 H). 13C NMR
(100 MHz, CDCl3):
190.7, 136.9, 134.8, 131.7, 131.3, 127.1,
126.3, 97.7, 95.3, 79.5, 76.9, 61.8, 61.6, 26.09, 26.06, 24.3, 18.5,
-5.04, -5.08 ppm. HRMS: calcd for C27H41BrO3Si2 548.1778,
found 548.1776.
46. See the Pd/Cu general procedure (Supporting Information). To a solution of 45 (2.04 g, 3.72 mmol), bis(triphenylphosphine)palladium(II) dichloride (0.261 g, 0.372 mmol), and
copper(I) iodide (0.142 g, 0.744 mmol) in THF (15 mL) were
added via cannula Et3N (20 mL) and 12 (1.48 g, 6.32 mmol)
in THF (25 mL). The mixture was stirred at 70
C for 1 d.
Purification by flash chromatography (silica gel, hexanes/CHCl3 25/75) afforded 2.46 g (94% yield) of the title compound
as a yellow oil. IR (KBr): 3371, 2958, 2931, 2857, 2233, 1783,
1696, 1585, 1467, 1386, 1334, 1255, 1105 cm-1. 1H NMR (400
MHz, CDCl3):
10.45 (s, 1 H), 7.93 (s, 1 H), 7.61 (s, 1 H), 7.45
(d, J = 1.5 Hz, 2 H), 7.43 (t, J = 1.5 Hz, 1 H), 3.87 (t, J = 7.1
Hz, 4 H), 2.74 (m, 4 H), 2.39 (t, J = 7.0 Hz, 4 H), 1.62 (sext,
J = 7.2 Hz, 4 H), 1.05 (t, J = 7.3 Hz, 6 H), 0.92 (s, 9 H), 0.88
(s, 9 H), 0.10 (s, 6 H), 0.07 (s, 6 H). 13C NMR (100 MHz,
CDCl3):
191.0, 136.6, 135.3, 135.0, 133.8, 130.7, 130.6, 126.2,
125.0, 123.1, 96.9, 95.8, 94.4, 91.9, 87.9, 79.6, 79.5, 62.0, 61.7,
26.1, 24.3, 22.3, 21.6, 18.6, 18.5, 13.7, -5.05, -5.09. No signal
for the molecular ion could be obtained by HRMS.
47. In a flask equipped with a condenser was dissolved a
solution of the aldehyde 46 (1.58 g, 2.25 mmol), ethylene glycol
(1 mL, 17.98 mmol), and TMSCl (1.75 mL, 13.68 mmol,
distilled over CaH2) in 100 mL of CH2Cl2. This solution was
heated to reflux for 20 h after which aq NaOH was added until
the solution was basic. The mixture was extracted with CH2Cl2. The combined organic phases were dried over MgSO4 and
filtered and the solvent evaporated in vacuo. Purification by
flash chromatography (silica gel, hexanes/EtOAc 40/60) afforded a mixture of the product as well as the TBS-protected
47. The mixture was submitted to a TBS-deprotection with
TBAF (4.0 mL, 4.0 mmol) in THF (40 mL) for 25 min. The
reaction mixture was diluted with water and extracted with
Et2O. The combined organic phases were dried over MgSO4
and filtered, and the solvent was evaporated in vacuo. Purification by flash chromatography (silica gel, hexanes/EtOAc
25/75) afforded 417 mg (36% yield) of the title compound as a
white solid. This compound is light and moisture sensitive,
and it should be used immediately or stored under nitrogen
in the freezer. Mp: 115-116
C. IR (KBr): 3372, 2961, 2931,
2873, 2230, 1601, 1581, 1485, 1461, 1387, 1341, 1167, 1078,
1044 cm-1. 1H NMR (400 MHz, CDCl3):
7.63 (s, 1 H), 7.54
(s, 1 H), 7.45 (d, J = 1.5 Hz, 2 H), 7.39 (t, J = 1.5 Hz, 1 H),
6.17 (s, 1 H), 4.14-4.04 (m, 4 H), 3.83 (m, 4 H), 2.81 (t, J =
6.2 Hz, 2 H), 2.70 (t, J = 6.2 Hz, 2 H), 2.38 (t, J = 7.0 Hz, 4
H), 2.04 (m, 1 H), 1.62 (sext, J = 7.2 Hz, 4 H), 1.05 (t, J = 7.3
Hz, 6 H). 13C NMR (100 MHz, CDCl3):
139.6, 135.5, 134.9,
133.7, 129.4, 126.2, 125.4, 124.9, 123.3, 122.2, 101.6, 94.9, 92.9,
92.8, 91.7, 88.1, 81.25, 79.6, 65.6, 61.3, 61.2, 24.5, 24.3, 22.3,
21.6, 13.7. HRMS: calcd for C35H34O4 518.2457, found 518.2460.
48. To a flask equipped with a condenser was added a
solution of the aldehyde 46 (1.97 g, 2.80 mmol), 2,2-dimethyl-1,3-propanediol (2.33 g, 22.42 mmol), TMSCl (1.79 mL, 134.01
mmol, distilled over CaH2) in CH2Cl2 (150 mL). The solution
was heated to reflux for 18 h after which time aq NaOH was
added until the solution became basic. The mixture was
extracted with CH2Cl2. The combined organic phases were
dried over MgSO4 and filtered, and the solvent was evaporated
in vacuo. Purification by flash chromatography (silica gel,
hexanes/EtOAc 50/50) afforded a mixture of the product as well
as the bis-TBS-protected ether. The mixture was submitted
to a TBS-deprotection with TBAF (3.25 mL, 3.25 mmol) in THF
(60 mL) for 20 min. The reaction mixture was diluted with
water and extracted with Et2O. The combined organic phases
were dried over MgSO4 and filtered, and the solvent wasevaporated in vacuo. Purification by flash chromatography (silica
gel, hexanes/EtOAc 50/50) afforded 1.17 g (75% yield) of the
title compound as a white solid. Mp: 110-111
C. IR (KBr):
3436, 2963, 2936, 2873, 2251, 1582, 1466, 1386, 1097 cm-1.
1H NMR (400 MHz, CDCl3):
7.77 (s, 1 H), 7.54 (s, 1 H), 7.45
(d, J = 1.5 Hz, 2 H), 7.39 (t, J = 1.5 Hz, 1 H), 5.67 (s, 1 H),
3.84-3.76 (m, 6 H), 3.66 (d, J = 10.9 Hz, 2 H), 2.78 (t, J = 6.2
Hz, 2 H), 2.73 (t, J = 6.2 Hz, 2 H), 2.38 (t, J = 7.0 Hz, 4 H),
1.62 (sext, J = 7.2 Hz, 4 H), 1.31 (s, 3 H), 1.05 (t, J = 7.3 Hz,
6 H), 0.80 (s, 3 H). 13C NMR (100 MHz, CDCl3):
139.4, 135.6,
134.8, 133.7, 130.0, 125.9, 125.7, 124.8, 123.3, 121.5, 99.5, 93.1,
92.7, 92.6, 91.7, 88.2, 81.3, 79.6, 79.2, 78.0, 61.2, 30.5, 24.34,
24.28, 23.3, 22.3, 22.0, 21.5, 14.4. HRMS: calcd for C38H40O4
560.2927, found 560.2928.
50. To a solution of the alcohol 48 (1.17 g, 2.09 mmol) and
DMAP (40 mg, 0.334 mmol) in CH2Cl2 (20 mL) cooled to 0
C
were added pyridine (0.85 mL, 10.44 mmol) and a 0
C solution
of p-nitrophenylchloroformate (1.66 g, 8.22 mmol) in CH2Cl2
(10 mL). This yellow milky solution was stirred at 0
C for
1.25 h after which a solution of saturated aq NaHCO3 was
slowly added to quench the reaction. The mixture was extracted with CH2Cl2. The combined organic phases were dried
over MgSO4 and filtered and the solvent evaporated in vacuo.
Purification by flash chromatography (silica gel, hexanes/EtOAc 50/50) afforded 1.61 g (87% yield) of the title compound
as a white sticky solid. Mp: 23-58
C. IR (KBr): 2964, 2253,
1767, 1595, 1528, 1469, 1385, 1350, 1218, 1165, 1097 cm-1.
1H NMR (400 MHz, CDCl3):
8.29 (m, 2 H), 8.25 (M, 2 H),
7.80 (s, 1 H), 7.57 (s, 1 H), 7.43 (d, J = 1.5 Hz, 2 H), 7.39 (m,
2 H), 7.37 (t, J = 1.5 Hz, 1 H), 7.35 (m, 2 H), 5.72 (s, 1 H), 4.51
(dt, J = 6.6, 2.0 Hz, 4 H), 3.76 (d, J = 11.1 Hz, 2 H), 3.68 (d,
J = 10.9 Hz, 2 H), 2.99 (m, 4 H), 2.35 (t, J = 7.0 Hz, 4 H), 1.60
(sext, J = 7.2 Hz, 4 H), 1.31 (s, 3 H), 1.04 (t, J = 7.3 Hz, 6 H),
0.78 (s, 3 H). 13C NMR (100 MHz, CDCl3):
155.6, 155.5,
152.6, 152.4, 145.7, 145.5, 139.5, 135.8, 134.8, 133.7, 130.3,
126.0, 125.7, 125.6, 125.4, 124.8, 123.3, 122.0, 121.9, 121.4,
99.5, 92.8, 91.7, 90.9, 90.6, 87.9, 81.2, 79.5, 79.2, 78.0, 66.9,
30.5, 23.3, 22.3, 22.0, 21.5, 20.5, 20.4, 13.7. MALDI MS
(dithranol, Ag): calcd for C52H46N2O12 890.3, found 890.
Synthesis of Dimers 51 and 52 and Polymer 53.
Compounds 47 (113.9 mg, 0.2196 mmol) and 50 (195.7 mg,
0.2196 mmol) were carefully weighed into a round-bottom
flask, and DMAP (67 mg, 0.549 mmol) was added. After
removal of the oxygen, CH2Cl2 (5 mL) was added, and the
solution was stirred at rt for 21 h after which a solution of
NaHCO3 was added to quench the reaction. The mixture was
extracted with CH2Cl2. The combined organic phases were
dried over MgSO4 and filtered, and the solvent was evaporated
in vacuo. Purification by flash chromatography (silica gel,
hexanes/EtOAc 50/50 then EtOAc) afforded 51 and 52, 56 mg
(23%) and 52 mg (21%) (the two isomers could not be clearly
distinguished between each other although they were separable), and 42 mg of 53. Compounds 51 or 52 (the less polar
of the two, blue spot on TLC under UV irradiation). IR (KBr):
2962, 2933, 2905, 2872, 2234, 1748, 1581, 1464, 1401, 1337,
1267, 1097 cm-1. 1H NMR (400 MHz, CDCl3):
7.68 (s, 1 H),
7.51 (s, 1 H), 7.43 (s, 1 H), 7.42 (d, J = 1.5 Hz, 2 H), 7.39 (s, 1
H), 7.37 (t, J = 1.5 Hz, 2 H), 7.35 (d, J = 1.5 Hz, 2 H), 5.96 (s,
1 H), 5.55 (s, 1 H), 4.33 (m, 8 H), 3.93 (m, 4 H), 3.64 (s, 2 H),
3.55 (d, J = 10.2 Hz, 1 H), 3.38 (d, J = 10.2 Hz, 1 H), 2.88 (m,
8 H), 2.36 (m, 8 H), 1.60 (m, 8 H), 1.17 (s, 3 H), 1.04 (m, 12 H),
0.72 (s, 3 H). 13C NMR (100 MHz, CDCl3):
155.2, 155.1, 139.8,
139.2, 135.9, 135.2, 134.6, 134.5, 134.0, 133.9, 133.7, 129.8,
129.7, 126.1, 125.5, 125.3, 125.1, 124.8, 124.6, 124.5, 123.7,
123.6, 122.3, 121.7, 101.4, 99.3, 92.5, 92.2, 91.8, 91.4, 91.2, 91.1,
88.7, 81.0, 79.8, 79.7, 78.8, 78.0, 66.2, 66.1, 66.0, 65.5, 65.4,
30.2, 23.2, 22.31, 22.29, 22.26, 22.0, 21.5, 20.5, 20.4, 20.2, 13.7.
MALDI (dithranol, Ag): calcd for C75H70O10 1130.5, found
1130.4. GPC (THF, PS): Mn = 775, Mw = 800. 51 or 52 (the
more polar of the two, gray-black spot on TLC under UV
irradiation). IR (KBr): 2963, 2933, 2872, 2250, 1746, 1581,
1464, 1401, 1269, 1096 cm-1. 1H NMR (400 MHz, CDCl3):
7.64 (s, 1 H), 7.48 (s, 1 H), 7.43 (d, J = 1.3 Hz, 2 H), 7.39 (t,
J = 1.4 Hz, 4 H), 7.35 (t, J = 1.5 Hz, 1 H), 7.32 (t, J = 1.5 Hz,
1 H), 6.01 (s, 1 H), 5.61 (s, 1 H), 4.39-4.30 (m, 8 H), 3.98-3.90 (m, 4 H), 3.68 (s, 2 H), 3.57 (d, J = 10.2 Hz, 1 H), 3.52 (d,
J = 10.2 Hz, 1 H), 2.95-2.81 (m, 8 H), 2.38 (m, 8 H), 1.60 (m,
8 H), 1.21 (s, 3 H), 1.07 (m, 12 H), 0.76 (s, 3 H). 13C NMR (100
MHz, CDCl3):
155.2, 155.0, 139.6, 139.1, 135.9, 135.4, 134.7,
134.5, 133.94, 133.91, 133.7, 130.0, 129.9, 126.1, 125.7, 125.6,
125.5, 124.5, 123.8, 123.6, 121.6, 121.1, 101.5, 99.4, 92.7, 92.3,
92.1, 91.5, 91.4, 91.2, 88.4, 88.1, 80.8, 80.7, 79.9, 79.8, 79.3,
79.2, 78.0, 66.3, 66.2, 66.0, 65.9, 65.5, 30.3, 29.9, 23.3, 22.32,
22.26, 22.1, 21.6, 21.2, 20.5, 20.4, 14.4, 13.7. MALDI (dithranol,
Ag): calcd for C75H70O10 1130.5, found 1130.5. GPC (THF,
PS): Mn = 745, Mw = 765. 53 (blue tailing spot on TLC under
UV irradiation). IR (KBr): 2965, 2934, 2873, 2253, 1746, 1581,
1463, 1402, 1256 cm-1. 1H NMR (400 MHz, CDCl3):
7.75
(br s, 1 H), 7.62 (br s, 1 H), 7.54 (t, J = 1.5 Hz, 1 H), 7.52 (t,
J = 1.4 Hz, 1 H), 7.44 (m, 4 H), 7.39 (br t, 2 H), 6.10 (s, 0.5 H),
6.08 (s, 0.5 H), 5.67 (br t, 1 H), 4.39-4.30 (m, 8 H), 4.15-4.03
(m, 4 H), 3.76 (dd, J = 10.9, 3.67 Hz, 2 H), 3.66 (d, J = 10.7
Hz, 1 H), 2.93-2.82 (m, 8 H), 2.38 (m, 8 H), 1.60 (m, 8 H),
1.21 (d, J = 4.0 Hz, 3 H), 1.07 (m, 12 H), 0.80 (d, J = 4.0 Hz,
3 H). 13C NMR (100 MHz, CDCl3):
154.9, 154.8, 154.8, 139.5,
139.1, 136.0, 135.6, 134.74, 133.72, 130.3, 130.1, 126.1, 125.8,
125.7, 125.5, 124.83, 124.81, 123.4, 122.2, 121.5, 101.4, 99.5,
92.9, 92.7, 91.7, 90.7, 88.1, 87.9, 81.0, 79.6, 78.9, 78.0, 65.9,
65.8, 65.7, 30.4, 29.9, 23.3, 22.3, 22.0, 21.5, 21.2, 20.4, 13.7.
LDI MS: a broad peak centered at 47,536. GPC (THF, PS):
Mn = 23,500, Mw = 36,600.
Rice University primarily supported this work, with partial support from Zyvex LLC and the Welch Foundation. The National Science Foundation, CHEM 0075728, provided partial funds for the 400 MHz NMR instrument. Dr. Ian Chester at FAR Research kindly provided the trimethylsilylacetylene. Chemetall Chemical Products, Inc., graciously provided cesium carbonate.
General procedures and preparations of 1, 6-8, the diols, 26, 27, 43, and 49, as well as copies of 1H and 13C NMR spectra of most compounds. This material is available free of charge via the Internet at http://pubs.acs.org.
* To whom correspondence should be addressed. Phone: 713-348-6246. Fax: 713-348-6250.
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a The cyclic diols for entries 5 and 7 were prepared by catalytic OsO4 dihydroxylation of the corresponding cycloalkenes. The diols for entries 2 and 6 were prepared by reductive pinacol coupling of the 1,4- and 1,5-diketones with SmI2 and Mg/TiCl4, respectively.b Ratios determined by 1H NMR using the diastereotopic acetal protons that were consistently well-separated.c NanoChef (22) was synthesized using chlorotrimethylsilane (5 equiv) in dichloromethane.d Yields based on recovered NanoKid (13) for entries 2, 6, and 9 were 33%, 58%, and 20%, respectively.