Facile synthesis of benzo[b]thiophenes via metal-free radical-triggered intramolecular C-S bond formation.

A facile method for the synthesis of benzo[b]thiophenes with good to excellent yields via metal-free intramolecular C-S bond formation has been developed by utilizing I as a catalyst and O from air as an oxidant (20 examples). Its notable features such as catalytic I, intramolecular C-S bond formation, short reaction times, and broad functional group tolerance make this strategy highly attractive. The purification of products only needs washing with solvents, thereby avoiding traditional chromatography and recrystallization, which belongs to group-assisted purification (GAP) chemistry.