Three-Component Photochemical Cyclization/Dithiocarbamate Formation of gem-Difluoro Quinolin-2(1H)-ones

Herein, a novel visible-light-induced 6-exo-trig difluoromethylation cyclization and subsequent carbo-thioesterification reaction is described. This protocol allows efficient access to valuable gem-difluoro quinolin-2(1H)-ones in moderate to excellent yields under mild conditions. Broad amino sources compatibility, including cyclic morpholine, thiazolidine, thiomorpholine, pyrrolidine, 1,4-oxazepane, 2,6-dimethylmorpholine, tert-butyl piperazine-1-carboxylate and noncyclic diethylamine, N-ethylpropan-1-amine, N-benzylethanamine, N-benzyl-trimethylsilanamine, dibenzylamine, and N-(4-methoxybenzyl)ethanamine, demonstrated the practicability of this strategy. A radical–radical crossover route was proposed on the basis of radical inhibition experiments, visible light irradiation on–off test, apparent quantum efficiency (AQE) calculation, and fluorescence quenching studies.