1-Phosphino-2-sulfenylferrocenes as Planar Chiral Ligands in Enantioselective Palladium-Catalyzed Allylic Substitutions

Olga García Mancheño, Julián Priego, Silvia Cabrera, Ramón Gómez Arrayás, Tomás Llamas, and Juan Carlos Carretero*
Departamento de Qumica Orgnica, Facultad de Ciencias, Universidad Autnoma de Madrid, Cantoblanco 28049 Madrid, Spain
J. Org. Chem., 2003, 68 (9), pp 3679–3686
DOI: 10.1021/jo0340657
Publication Date (Web): April 9, 2003
Copyright © 2003 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, juancarlos.carretero@uam.es

Abstract

Abstract Image

The synthesis of a wide structural variety of enantiopure 1-phosphino-2-sulfenylferrocene ligands 1 possessing exclusively planar chirality is described. In the case of the readily available tert-butylsulfenyl derivatives very high enantioselectivities were obtained in the palladium-catalyzed allylic substitution of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate (ee's up to 97%) and nitrogen nucleophiles (ee's up to 99.5%). Palladium complexes of these ferrocenes were characterized by NMR and X-ray diffraction, revealing the P,S-bidentate character of the ligands 1 and the formation of a single epimer on the stereogenic sulfur atom resulting from the complexation with palladium. A model justifying the observed asymmetric induction exerted by this novel family of chiral ferrocenes, supported by solution NMR studies on a palladium allylic complex, is discussed.

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  • Published In Issue May 02, 2003
  • Received January 20, 2003

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