Electrochemical Synthesis of Macrocyclic Iminoisocoumarins by Rh-Catalyzed Intramolecular Vinylic C-H Activation/Heterocyclization.

Herein, we report a new macrocyclization strategy via electrochemical Rh(III)-catalyzed intramolecular vinylic C-H activation and subsequent heterocyclization. This approach affords diverse iminoisocoumarin-braced macrocycles with 13- to 28-membered rings bearing various functional groups in good yields with excellent regioselectivity under mild electrooxidation conditions. Mechanistic studies, including isolation and characterization of a key Rh(I) sandwich intermediate, along with cyclic voltammetry analysis, provide evidence for a rhodium(III/I) catalytic regime.