Dark and Light Reactions of Carbenes─Merging Carbene Transfer Reactions with N-Heterocyclic Carbene Catalysis for the Synthesis of Hydroxamic Acid Esters

Herein, we report visible light and N-heterocyclic carbene (NHC) jointly promoted multicomponent carbene transfer reactions. Under the optimized reaction conditions, two kinds of important hydroxamic acid esters were obtained in good yields depending on the reaction media used. The key to this success was driven by the blue light-promoted generation of free carbene species and the fast in situ formation of hydroxamic acid under NHC-catalyzed conditions. The mild reaction conditions, excellent functional group tolerance, useful synthetic transformations, and successful modification of natural products and drug molecules proved the utility and practicality of this method.