Lewis base catalyzed aldol additions of chiral trichlorosilyl enolates and silyl enol ethers

Scott E. Denmark, Shinji Fujimori, Son M. Pham

Research output: Contribution to journalArticle

Abstract

The consequences of double diastereodifferentiation in chiral Lewis base catalyzed aldol additions using chiral enoxysilanes derived from lactate, 3-hydroxyisobutyrate, and 3-hydroxybutyrate have been investigated. Trichlorosilyl enolates derived from the chiral methyl and ethyl ketones were subjected to aldolization in the presence of phosphoramides, and the intrinsic selectivity of these enolates and the external stereoinduction from chiral catalyst were studied. In the reactions with the lactate derived enolate, the strong internal stereoinduction dominated the stereochemical outcome of the aldol addition. For the 3-hydroxyisobutyrate- and 3-hydroxybutyrate derived enolates, the catalyst-controlled diastereoselectivities were observed, and the resident stereogenic centers exerted marginal influence. The corresponding trimethylsilyl enol ethers were employed in SiCl4/bisphosphoramide catalyzed aldol additions, and the effect of double diastereodifferentiation was also investigated. The overall diastereoselection of the process was again controlled by the strong external influence of the catalyst.

Original languageEnglish (US)
Pages (from-to)10823-10840
Number of pages18
JournalJournal of Organic Chemistry
Volume70
Issue number26
DOIs
StatePublished - Dec 23 2005

ASJC Scopus subject areas

  • Organic Chemistry

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