Copper-Catalyzed Protoarylation of gem -Difluoroallenes.

A copper-catalyzed protoarylation of gem -difluoroallenes with aryl boronic esters has been developed, enabling highly regioselective synthesis of gem -difluoroalkenes in high yields. The mild reaction conditions allow for a variety of functional groups to be tolerated, and the reaction can be extended to protoalkenylation of gem -difluoroallenes. The synthetic utility of this method has been demonstrated in gram-scale operation as well as synthesis of chiral gem -difluoroalkenes bearing γ-carbon stereogenic centers in moderate enantioselectivity using a chiral bidentate phosphine ligand with a copper catalyst.