NHC-Mediated Photochemical/Electrochemical Synthesis of Carbonyl Compounds

Great progress has been made in the photochemical/electrochemical reactions of carbonyl compounds catalyzed by N-heterocyclic carbenes (NHCs), allowing for many incredible reactions. The form of active intermediates hugely varies in different reactions. Under light or electricity, different active intermediates can be generated during NHC-catalyzed reactions depending on their interaction with different substrates and the reaction conditions. Intermediates can be converted into α,β-unsaturated acylazoliums, Breslow intermediates, homoenolates, and acylazoliums and subsequently undergo single- or double-electron conversions. This study reviews the different active intermediates formed by NHC in photochemical/electrochemical catalysis. 1 Introduction 2 NHC-Mediated Photoreactions 3 NHC-Mediated Electrochemical Reactions 4 Conclusion and Prospects