Stereoselective Fluoro-Deuteration/Chalcogenation/Halogenation of gem-Difluoroallenes (DFAs)

A practical and highly stereoselective approach for the synthesis of α-functionalized trifluoromethylated alkenes has been developed, enabling the incorporation of deuterium, halogen, or chalcogen atoms. The method accommodates a wide range of substrates and delivers the desired products in good yields with excellent E/Z selectivity. The reaction proceeds through a vinyl silver intermediate, formed via AgF addition to gem-difluoroallenes. Control experiments underscore the essential role of the gem-difluoro group in activating the α-carbon to initiate the reaction.