NHC-Catalyzed Reaction of Aldehydes for C(sp2)–O Bond Formation

Abstract

In the past few decades, N-heterocyclic carbenes (NHCs) have opened the new field of organocatalysis in synthetic organic chemistry. This review highlights the dramatic progress in the field of NHC-catalyzed C–O bond formation based on the activation of aldehyde C(sp2)–H bonds. The oxidative and redox transformations for the synthesis of various molecules with structural diversity and complexity are summarized. Furthermore, new methods and strategies for NHC catalysis are emerging continuously; thus, cooperative catalysis with Brønsted acid, hydrogen-bonding catalyst, transition-metal catalyst, and photocatalyst are also described.