Copper-Catalyzed Hydrodifluoroallylation of Terminal Alkynes to Access (E)-1,1-Difluoro-1,4-Dienes

A copper-catalyzed regio- and stereoselective hydrodifluoroallylation of terminal alkynes was disclosed. This reaction employs easily available 3-bromo-3,3-difluoropropene (BDFP) as the difluoroallylating reagent and 1,1,3,3-tetramethyldisiloxane (TMDSO) as the hydride source, affording a variety of (E)-1,1-difluoro-1,4-dienes in moderate to good yields. The synthetic utility of this protocol has been demonstrated through the transformation of resulting (E)-1,1-difluoro-1,4-diene to difluoromethylated and trifluoromethylated derivatives.