Titanium mediated asymmetric aldol reaction with alpha-fluoropropionimide enolates

Vincent A. Brunet, David O'Hagan, Alexandra M. Z. Slawin

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Aldol reaction utilising Evans N-(alpha-fluoropropyl)-2-oxazolidinones with TiCl4 have been explored. Reactions of N-(alpha-fluoropropyl)-2-oxazolidinones with aliphatic aldehydes generated (x-fluoro-p-hydroxy-aldol products with high diastereoselectivities. When (alpha R)- and (alpha S)-N-(alpha-fluoropropyl)-2-(4S)-oxazolidinones were explored as substrates they gave rise to identical aldol diastereoisomer products. Examination of the enolates formed in each case by F-19 NMR, after treatment with TiCl4, indicated that both preparations gave the same predominant enolate. This was assumed to be the E-enolate. The alpha-fluoro-beta-hydroxy-aldol products were removed from the auxiliary either by alcoholysis or reduction and converted to the corresponding alpha,beta-difluoro products by treatment with Deoxofluor (TM) (C) 2007 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)1271-1279
Number of pages9
JournalJournal of Fluorine Chemistry
Volume128
DOIs
Publication statusPublished - Oct 2007

Keywords

  • asymmetric synthesis
  • Evans auxiliary
  • alpha-Fluoroenolates
  • asymmetric aldol reactions
  • stereoselective fluorination
  • vicinal difluoro compounds
  • ENANTIOSELECTIVE SYNTHESIS
  • CONFORMATION

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