Mild and Copper-Free Stereoselective Cyanation of gem-Difluoroalkenes by Using Benzyl Nitrile as a Cyanating Reagent

A novel copper-free highly stereoselective cyanation of gem-difluoroalkenes by using benzyl nitrile as a cyanating reagent with the assistance of tBuOLi under air atmosphere at room temperature was developed. A variety of versatile fluorinated alkenyl nitriles were obtained. The proposed mechanism involved the C-H bond oxidation, C-CN bond cleavage, and then nucleophilic vinylic substitution (SNV).