NHC-promoted asymmetric β-lactone formation from arylalkylketenes and electron-deficient benzaldehydes or pyridinecarboxaldehydes

James Douglas, James E. Taylor, Gwydion Churchill, Alexandra M.Z. Slawin, Andrew D. Smith

Research output: Contribution to journalArticle

45 Citations (Scopus)

Abstract

A chiral NHC catalyzes the asymmetric formal [2 + 2] cycloaddition of alkylarylketenes with both electron-deficient benzaldehydes and 2- and 4-pyridinecarboxaldehydes to generate stereodefined β-lactones. In the benzaldehyde series, optimal product diastereo- and enantiocontrol is observed using 2-nitrobenzaldehyde (up to 93:7 dr (syn:anti) and 93% ee). Substituted 2- and 4-pyridinecarboxaldehydes are also tolerated in this process, generating the corresponding β-lactones in good yield and enantioselectivity, although the diastereocontrol in these processes is highly dependent upon the aldehyde substitution. These processes are readily scalable, allowing multigram quantities of the β-lactone products to be prepared. Derivatization of these products, either through ring opening into the corresponding stereodefined β-hydroxy and β-amino acid derivatives without loss of stereochemical integrity or via cross-coupling, is demonstrated.

Original languageEnglish
Pages (from-to)3925-3938
Number of pages14
JournalJournal of Organic Chemistry
Volume78
Issue number8
Early online date26 Feb 2013
DOIs
Publication statusPublished - 19 Apr 2013

ASJC Scopus subject areas

  • Organic Chemistry

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