Photoinduced Iron-Catalyzed Decarboxylation/Isomerization of gem-Difluoroallyl Carboxylic Acid to Access Vinyl Difluoromethylene Units.

Vinyl difluoromethylene units (-CF-) significantly enhance the bioactivity and physical and chemical properties of compounds. Despite recent advances in introducing vinyl difluoromethylene units, radical-mediated formation of these motifs remains largely unexplored. A novel serial catalytic strategy for selective defluoroalkylation of trifluoromethyl alkenes has been developed, utilizing photocatalytic defluorocarboxylation followed by photoinduced iron-catalyzed decarboxylation/isomerization. The defluoroalkylation reaction involves generating difluoroallyl radicals, tautomerizing to vinyl difluoromethylene radicals, and proceeding through radical addition and alkylation.