Photoredox-catalysed radical difluoromethylation/cyclization of N -acryloyl-2-arylbenzimidazole to access CF 2 H-substituted benzimidazo[2,1- a ]isoquinolin-6(5 H )-ones

An efficient visible-light-promoted cascade difluoromethylation/cyclization reaction to access various CF H-substituted benzimidazo[2,1- ]isoquinolin-6(5 )-ones was developed using difluoromethyltriphenylphosphonium bromide salt as the precursor of the -CF H group under mild conditions. This protocol utilized an easily accessible and inexpensive organophotocatalyst, offering the benefits of a broad substrate scope, good functional group tolerance, and good to excellent yields, in addition to a simple operational procedure. Furthermore, the reaction mechanism was subjected to investigation, and it was demonstrated that a radical pathway constitutes a single electron transfer (SET) procedure.