Cu-Catalyzed Asymmetric Allylic Alkylations of Aromatic and Aliphatic Phosphates with Alkylzinc Reagents. An Effective Method for Enantioselective Synthesis of Tertiary and Quaternary Carbons

Monica A. Kacprzynski and Amir H. Hoveyda*
Contribution from the Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467
J. Am. Chem. Soc., 2004, 126 (34), pp 10676–10681
DOI: 10.1021/ja0478779
Publication Date (Web): August 7, 2004
Copyright © 2004 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.

, amir.hoveyda@bc.edu

Abstract

Abstract Image

Efficient enantioselective Cu-catalyzed allylic alkylations of aromatic and aliphatic allylic phosphates bearing di- and trisubstituted olefins are disclosed. Enantioselective C−C bond forming reactions are promoted in the presence of 10 mol % readily available chiral amino acid-based ligand (5 steps, 40% overall yield synthesis) and 5 mol % (CuOTf)2·C6H6. Reactions deliver tertiary and quaternary stereogenic carbon centers regioselectively and in 78−96% ee. Data regarding the effect of variations in ligand structure on the efficiency and enantioselectivity of the alkylation process, as well as a mechanistic working model, are presented. The suggested model involves a dual role for the chiral Cu complex:  association of the Cu(I) center to the olefin is facilitated by a two-point binding between the carbonyl of the ligand's amide terminus and the PO of the substrate.

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History

  • Published In Issue September 01, 2004
  • Received April 13, 2004

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