Visible-Light-Induced Oxidation/[3 + 2] Cycloaddition/Oxidative Aromatization to Construct Benzo[a]carbazoles from 1,2,3,4-Tetrahydronaphthalene and Arylhydrazine Hydrochlorides

An efficient synthesis of benzo[ a ]carbazoles via visible-light-induced tandem oxidation/[3 + 2] cycloaddition/oxidative aromatization reactions was reported. The benzylic C(sp 3 )–H of tetrahydronaphthalene was activated through visible-light photoredox catalyst with oxygen as the clean oxidant under mild reaction conditions. This protocol proceeds efficiently with broad substrate scope, and the mechanism study was performed.