Oxidative Esterification, Thioesterification, and Amidation of Aldehydes by a Two-Component Organocatalyst System Using a Chiral N-Heterocyclic Carbene and Redox-Active Riboflavin

摘要

Flavin of the month! Triazolium-derived N-heterocyclic carbenes (NHCs) and a flavin catalyzed the oxidative esterification, thioesterification, and amidation of aldehydes with various alcohols, thiols, and amines, respectively, with O₂ as the terminal oxidant (see scheme; R1=aryl; R2, R3=alkyl or aryl). By using a chiral NHC catalyst, the enantioselective acylation promoted the kinetic resolution of racemic alcohols and the desymmetrization of a meso-diol.