C–F Activation of Fluorinated Esters Using Photocatalytically Generated Diaminoalkyl Radical

A method for hydrofluoroalkylation of alkenes with trifluoroacetic esters under visible light irradiation affording difluorinated products is described. The reaction involves readily available trimethyltriazinane as a shoichiometric reducing agent, which generates a diamino-substituted alkyl radical serving as a strong electron donor. It is believed that the cleavage of the C–F bond by a triazinane-derived radical involves single electron reduction coupled with fluoride transfer.