Copper-Catalyzed Difluoroalkylation Reaction

Divergent Generation of the Difluoroalkyl Radical and Difluorocarbene via Selective Cleavage of C-S Bonds of the Sulfox-CF2SO2Ph Reagent

A new difluoroalkylation reagent Sulfox-CF2SO2Ph bearing both sulfoximine and sulfone moieties was prepared from commercially available SulfoxFluor and PhSO2CF2H. On one hand, the Sulfox-CF2SO2Ph reagent could act as a (phenylsulfonyl)difluoromethyl radical source under photoredox catalysis, in which the arylsulfoximidoyl group is selectively removed. On the other hand, under basic conditions, Sulfox-CF2SO2Ph could serve as a difluorocarbene precursor for S- and O-difluoromethylations with S- and O-nucleophiles, respectively, in which the phenylsulfonyl group in Sulfox-CF2SO2Ph is selectively removed (followed by α-elimination of the arylsulfoximidoyl group).

Cobalt-catalyzed decarboxylative difluoroalkylation of nitrophenylacetic acid salts

The selective installation of fluorine-containing groups into biologically relevant molecules has been used as a common strategy for the development of pharmaceutically active molecules. However, the selective incorporation of gem-difluoromethylene groups next to sterically demanding secondary and tertiary alkyl groups remains a challenge. Herein, we report the first cobalt-catalyzed regioselective difluoroalkylation of carboxylic acid salts. The reaction allows for the facile construction of various difluoroalkylated products in good yields tolerating a wide range of functionalities on either reaction partner. The potential of the method is illustrated by the late-stage functionalization of molecules of biological relevance. Mechanistic studies support the in situ formation of a cobalt(i) species and the intermediacy of difluoroalkyl radicals, thus suggesting a Co(i)/Co(ii)/Co(iii) catalytic cycle.