Highly γ-Selective Arylation and Carbonylative Arylation of 3-Bromo-3,3-difluoropropene via Nickel Catalysis.

A nickel-catalyzed highly γ-regioselective arylation and carbonylative arylation of 3-bromo-3,3-difluoropropene has been developed. The reaction proceeds under mild reaction conditions, providing the gem-difluoroalkenes with high efficiency and good functional group tolerance. The resulting gem-difluoroalkenes can serve as versatile building blocks for diversified synthesis. Preliminary mechanistic studies and density functional theory calculations reveal that both non-radical and radical pathways are possible for the reaction, and the radical pathway is more likely. The high γ-regioselectivity results from the β-bromide elimination of alkylnickel(II) species or from the reductive elimination of nickel(III) species [(aryl)(CF2 =CHCH2 )NiIII (Ln )X]. The γ-selective carbonylation of 3-bromo-3,3-difluoropropene under 1 atm CO gas also provides a new way for nickel-catalyzed carbonylation.