Herein, a novel photocatalytic 6-exo-trig difluoromethylation cyclization and subsquent domino O2 trap version is described. This protocol allows efficient access to structurally diverse 4-(hydroxymethyl)-gem-difluoro-quinolines under mild conditions. Broad substrate scope, good functional group compatibility, biologically active molecule modification, scale-up operation, and further derivatization demonstrate the utility of this protocol. A radical cyclization route was proposed based on radical inhibition experiments, deuterium-labeled experiments, visible-light irradiation on-off test, apparent quantum efficiency (AQE) calculation, and Stern-Volmer fluorescence quenching experiments.
Sun et al. (2026) studied this question.