Lewis base catalyzed, enantioselective aldol addition of methyl trichlorosilyl ketene acetal to ketones

Scott E Denmark, Yu Fan, Martin D. Eastgate

Research output: Contribution to journalArticle

Abstract

The catalytic enantioselective addition of an acetate enolate equivalent to ketones is described. Methyl trichlorosilyl ketene acetal reacts with a wide range of ketones in the presence of pyridine N-oxide to afford the aldol addition products in excellent yields. Chiral 2,2′-pyridyl bis-N-oxides bearing various substituents at the 3,3′- and 6,6′-positions also provide excellent yields of the aldol products with variable enantioselectivities ranging from 94/6 er for aromatic ketones to nearly racemic for aliphatic ketones. An X-ray crystal structure of the complex between a catalyst and silicon tetrachloride (((P)-(R,R)-19-SiCl4)) has been obtained. Extensive computational analysis provides a stereochemical rationale for the observed trends in enantioselectivities.

Original languageEnglish (US)
Pages (from-to)5235-5248
Number of pages14
JournalJournal of Organic Chemistry
Volume70
Issue number13
DOIs
StatePublished - Jun 24 2005

ASJC Scopus subject areas

  • Organic Chemistry

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