Advances in acyl anion and homoenolate catalysis.

Umpolung catalysis involving carbonyls is a long-established concept in organic synthesis, but is arguably underdeveloped relative to other modes of catalysis. Acyl anion and homoenolate catalysis provides unique and rapid access to functional group arrays that may otherwise be challenging to synthesize directly. Catalysis is only feasible when a strict set of requirements is met, and to date only a small number of molecules are known to meet these criteria. This review highlights innovative advances that have been made in this field within the past four years and includes research aimed toward catalyst development, new reaction discovery and stereocontrol.