Catalytic Generation of Carbanions through Carbonyl Umpolung.

Carbonyl Umpolung is a powerful strategy in organic chemistry to construct complex molecules. Over the last years, versatile catalytic approaches for the generation of acyl anion equivalents from carbonyls have been developed, but methods to obtain alkyl carbanions from carbonyls in a catalytic fashions are still at an early stage. This Minireview summarizes recent progress in the generation of alkyl carbanions through catalytic carbonyl Umpolung. Two different catalytic approaches can be utilized to enable alkyl carbanion generation from carbonyl compounds: the catalytic Wolff Kishner reaction and the catalytic single-electron reduction of carbonyls and imines. We discuss the reaction scope, mechanistic insights, and synthetic applications of the methods as well as potential future developments.