Construction of fused heterocycles by visible-light induced dearomatization of nonactivated arenes.

A diverse array of fused [6-6-5] tricyclic heterocycles has been synthesized via the dimerization and dearomative cyclization of benzene derivatives under visible light irradiation. The initiation of the cascade process is likely from aryloxy radicals, engendered through proton-coupled electron transfer by the photoexcited vinylidene ortho-quinone methide (VQM) and a Brønsted base.