Photoredox Generation of N-Centered Hydrazonyl Radicals Enables the Construction of Dihydropyrazole-Fused gem-Difluoroalkenes.

An efficient visible-light-promoted N-radical-mediated tandem radical cyclization/defluorinated alkylation of ß,γ-unsaturated hydrazones, and α-trifluoromethyl alkenes is described. This protocol provides a general and effective route to synthesize various dihydropyrazole-fused gem-difluoroalkenes at moderate to excellent yields under redox-neutral, metal-free, and mild conditions.