Copper-Catalyzed Carboxylation of C-F Bonds with CO2

An effective Cu-catalyzed selective formal carboxylation of C-F bonds with an atmospheric pressure of CO2 is reported. A variety of gem-difluoroalkenes, gem-difluorodienes, and alpha-trifluoro-methyl alkenes show high reactivity and selectivity for this ipso monocarboxylation. Under mild conditions, diverse important alpha-fluoroacrylic acids and alpha,alpha-difluorocarboxylates are obtained in good-to-high yields. Moreover, this operationally simple protocol features good functional group tolerance, is readily scalable, and the resulting products are readily converted into bioactive alpha-fluorinated carbonyl compounds, indicating potential application in biochemistry and drug discovery. Mechanistic studies reveal that fluorinated boronate esters might be vital intermediates in this transformation.