Access to β-Keto Amino Acid Derivatives via Interrupted Polonovski Strategy Involving NHC-Catalyzed Aza Benzoin Reaction

A general and practical route to the synthesis of β-keto amino acid derivatives from aldehydes and bench stable imine surrogates is presented. Following the interrupted Polonovski strategy, the imine formed in situ was trapped by the catalytically generated Breslow intermediate in an aza benzoin reaction. The present strategy has been extended to the formal synthesis of florfenicol and an intermediate en route to vancomycin. The functionalization of the synthesized β-keto amino acid derivatives highlights the practical applicability of the current methodology.