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A green and efficient protocol for the preparation of benzo[ a ]carbazoles via visible-light-promoted and electron donor-acceptor (EDA) complex-driven intermolecular cyclization of 2-arylindoles with Z -α-bromocinnamaldehydes in the absence of external photocatalysts, transition metals, and oxidants was reported. This new approach demonstrates an intermolecular cyclization model using indole derivatives as electron donors under visible light. Mechanistic investigations have showed that 2-arylindoles with Z -α-bromocinnamaldehydes form EDA complexes, which undergo sequential single-electron transfer, radical coupling, 6π-electrocyclization, and dehydroaromatization to generate benzo[ a ]carbazoles under visible light irradiation. The current photochemical method features readily accessible starting materials, mild conditions, simple operation, and a broad substrate scope.

A metal-free, light-induced regiodivergent functionalization of α,β-unsaturated amides with aryltriazenes under ambient conditions was developed. The visible light and B(C 6 F 5 ) 3 cocatalyzed radical cascade arylation/cyclization of N -alkyl- N -arylmethacrylamides can obtain functionalized 3,3-disubstituted oxindoles with the assistance of photocatalyst eosin Y-Na 2 . In the absence of any catalyst, with purple light irradiation and electron-donor-acceptor (EDA) complex initiation, the radical cascade arylation/hydroxylation of N -arylmethacrylamides affords α-hydroxylamides. This methodology highlights the arts in accessing different regioisomers by altering the substrates and photocatalytic strategies.

A photoinduced deuterodetriazenation of aryltriazenes with CDCl 3 under catalyst-free conditions is reported. The reactions featured simple operation, ecofriendly conditions, readily available reagents, inexpensive D sources, precise site selectivity, and a wide range of substrates. Since aryltriazenes could be readily synthesized from arylamine, this protocol can be used as a general method for easily and accurately incorporating deuterium into aromatic systems by using CDCl 3 as a D source.

A visible-light-promoted metal-free catalytic system was developed to achieve the aminothiolation of α-bromocinnamaldehydes. This mechanistically novel approach allows the synthesis of diverse imidazo[2,1- b ]thiazole derivatives in satisfactory yields at room temperature under visible-light irradiation by incorporation of two distinct photoinduced processes. The reaction features readily accessible feedstocks, easy operation, mild reaction conditions, and wide reaction scope.