Unified strategy for the α-functionalization of esters, imides, and ketones via enolonium species

Enolate umpolung which yield enolonium species have recently emerged as a powerful strategy for the α-functionalization of carbonyl compounds. However, the current methodology is limited to specific classes of carbonyl compounds. Furthermore, the few existing methods are limited with respect to nucleophiles. Herein, we describe a unified strategy for α-functionalization that is compatible with both ketones and, for the first time, the carboxylic acid derivatives esters and imides. This method is compatible with numerous nucleophiles allowing for C–C and C–N bond formation, including asymmetrically. We show evidence for the formation of an ester enolonium species.