Photocatalyzed Three-Component Difluoroalkyl-Halogenation of Electron-Deficient Alkenes via a Halogen α-Nucleophilic Addition.

Here,we disclose a halogen α-nucleophilic addition via photocatalytic oxidation of the in-situ generated α-carbonyl radical of amides or esters to corresponding α-carbonyl cation. The α-carbon radical is generated by the β-addition of difluoroalkyl radical, formed by the photocatalytic reduction of BrCF2CO2R, to the α,β-unsaturated amides/esters. This umpolung strategy enables an efficient three-component difluoroalkyl-halogenation of α,β-unsaturated amides or esters with BrCF2CO2R and Cl/F-nucleophiles to produce diverse biologically important CF2-containing α-halo-1,5-dicarboxylic derivatives under mild conditions.