Intermolecular Trifluoromethyl-Hydrazination of Alkenes Enabled by Organic Photoredox Catalysis.

A metal-free and redox-neutral trifluoromethyl-hydrazination method of alkenes is described. With a commercially available photocatalyst and low-cost reagents, both conjugated and isolated alkenes could be converted to β-trifluoromethyl hydrazines in good to excellent yields. The versatile hydrazine group can be either used for heterocycle synthesis or cleaved to afford a corresponding amine. Mechanistic studies suggested this reaction goes through a radical addition cascade pathway, featuring a fast and irreversible trifluoromethylation and a relatively slow radical hydrazination step.