Catalytic conjugate additions of carbonyl anions under neutral aqueous conditions

Michael C. Myers, Ashwin R. Bharadwaj, Benjamin C. Milgram, Karl A Scheidt*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

97 Scopus citations

Abstract

The conjugate addition of carbonyl anions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of α-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonyl anions in a buffered protic environment that readily undergo conjugate additions to substituted α,β-unsaturated 2-acyl imidazoles. The scope of the reaction has been examined and found to accommodate various α-keto carboxylates and β-aryl substituted unsaturated 2-acyl imidazoles. The optimal precatalyst for this process is the commercially available thiazolium salt 5, a simple analogue of thiamin diphosphate. In this process, no benzoin products from carbonyl anion dimerization are observed. The corresponding 1,4-dicarbonyl compounds can be efficiently converted into esters and amides by way of activation of the N-methylimidazole ring via alkylation.

Original languageEnglish (US)
Pages (from-to)14675-14680
Number of pages6
JournalJournal of the American Chemical Society
Volume127
Issue number42
DOIs
StatePublished - Nov 1 2005

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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