Photoredox-catalysed radical difluoromethylation/cyclization of N-acryloyl-2-arylbenzimidazole to access CF2H-substituted benzimidazo[2,1- a]isoquinolin-6(5 H)-ones

Org Biomol Chem. 2024 Oct 15. doi: 10.1039/d4ob01413h. Online ahead of print.

Abstract

An efficient visible-light-promoted cascade difluoromethylation/cyclization reaction to access various CF2H-substituted benzimidazo[2,1-a]isoquinolin-6(5H)-ones was developed using difluoromethyltriphenylphosphonium bromide salt as the precursor of the -CF2H 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.