Imidazo[1,5-a]pyridin-3-ylidene-catalyzed Oxidative Esterification of Aldehyde: Remarkable Electronic Effect Regarding π-accepting Character of Ring-fused N-Heterocyclic Carbene

Imidazo[1,5-a]pyrid-3-ilydene(IPC)-catalyzed oxidative esterification of aldehydes was investigated. The series of IPC showed good catalytic activity, in particular, sterically hindered one. Substituents on the 3-position of imidazo[1,5-a]pyridine ring significantly influenced its catalytic activity, and electron-withdrawing substituent accelerated the reaction.