Metal-free Photoinduced Defluorinative Carboxylation of Trifluoromethylalkenes with Formate

Herein, we report an efficient protocol in which formate is used as a precursor of the CO2 radical anion for the photoinduced defluorocarboxylation of α-trifluoromethylstyrene. A wide range of gem-difluorovinylacetic acids bearing a variety of functional groups were successfully obtained in the absence of metal catalysts. The synthetic value of this protocol was highlighted by successful gram-scale synthesis and late-stage modification for complex biologically active molecules. This protocol provides a complementary method that extends the range of currently available methodologies for accessing the structurally versatile gem-difluoroalkenes.