Access to β‑Keto\nAmino Acid Derivatives\nvia Interrupted Polonovski Strategy Involving NHC-Catalyzed Aza Benzoin\nReaction

A general and practical route to\nthe synthesis of β-keto\namino acid derivatives from aldehydes and bench stable imine surrogates\nis presented. Following the interrupted Polonovski strategy, the imine\nformed in situ was trapped by the catalytically generated Breslow\nintermediate in an aza benzoin reaction. The present strategy has\nbeen extended to the formal synthesis of florfenicol and an intermediate\nen route to vancomycin. The functionalization of the synthesized β-keto\namino acid derivatives highlights the practical applicability of the\ncurrent methodology.