Visible‐Light‐Driven Enantioselective Aerobic Oxidation of β‐Dicarbonyl Compounds Catalyzed by Cinchona‐Derived Phase Transfer Catalysts in Batch and Semi‐Flow

Abstract

Abstract The direct asymmetric α‐hydroxylation of β‐dicarbonyl compounds has been developed using cinchona‐derived phase‐transfer catalysts in batch and semi‐flow processes. Using visible light as the driving force and air as oxidant, the corresponding products were obtained in excellent yields (up to 96%) and good enantioselectivities (up to 90% ee). The catalyst acts as a chiral center and a catalytic center and forms a chiral enolate complex with the substrate to act as a photosensitive center in the reaction. The use of semi‐flow photochemical processes allowed a reduction in reaction time (24 h to 0.89 h) and good yields (up to 93%) and enantioselectivities (up to 88% ee) were obtained. magnified image