Fluorohalogenation of gem-Difluoroalkenes: Synthesis and Applications of α-Trifluoromethyl Halides

A novel strategy for 1,2-dihalogenation of alkenes is reported that occurs through a sequential nucleophilic halide addition and electrophilic halogenation. By trapping the in situ generated unstable α-trifluoromethyl carbanion intermediates derived from the nucleophilic fluoride addition to electron-poor gem-difluoroalkenes, this fluorohalogenation of gem-difluoroalkenes with electrophilic haloalkynes affords various useful α-trifluoromethyl halides in high yields. A pesticidal active compound and various attractive trifluromethylated molecules could be smoothly synthesized from these obtained α-trifluoromethyl halides.