Asymmetric Addition of Alkylzinc Reagents to Cyclic α,β-Unsaturated Ketones and a Tandem Enantioselective Addition/Diastereoselective Epoxidation with Dioxygen

Sang-Jin Jeon and Patrick J. Walsh*
P. Roy and Diane T. Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323
J. Am. Chem. Soc., 2003, 125 (32), pp 9544–9545
DOI: 10.1021/ja036302t
Publication Date (Web): July 22, 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.

, pwalsh@sas.upenn.edu

Abstract

Abstract Image

Although over 100 catalysts have been reported to catalyze the asymmetric addition of alkyl groups to aldehydes, these catalysts fail to promote additions to ketones with >90% enantioselectivity. This paper describes the asymmetric 1,2-addition of alkyl groups to conjugated cyclic enones to give allylic alcohols with chiral quaternary centers. The resultant allylic alcohols are converted into epoxy alcohols with excellent diastereoselectivities. Treatment of the epoxy alcohols with BF3·OEt2 induces a semipinacol rearrangement to provide α,α-dialkyl-β-hydroxy ketones with all-carbon chiral quaternary centers. We also report a one-pot procedure for the asymmetric addition/diastereoselective epoxidation reaction. Simply exposing the reaction mixture to dioxygen after the asymmetric addition reaction is complete results in epoxidation of the allylic alcohol with high diastereoselectivity.

View: Full Text HTML | Hi-Res PDF

Tools

History

  • Published In Issue August 13, 2003
  • Received May 23, 2003

Recommend & Share

Related Content

Other ACS content by these authors: