Visible-Light-Promoted Iododifluoromethylation of Alkenes via (Phosphonio)difluoromethyl Radical Cation

A reaction of an iododifluoromethylphosphonium salt with unactivated alkenes mediated by peri-xanthenoxanthene under blue-light irradiation is described. The reaction proceeds via activation of the carbon–iodine bond to generate (phosphonio)­difluoromethyl radical cation, which attacks the double bond with subsequent quenching by the iodine. The intermediate phosphonium salts are easily hydrolyzed, furnishing products of iododifluoromethylation of alkenes.