We report an efficient radical-mediated CÀ C coupling through photoredox-catalyzed reactions of 4alkyl-dihydropyridines (DHPs) and vinylbenziodoxol-(on)es (VBX, VBO). This transition-metal-free and mild photocatalytic method has excellent functional group tolerance and affords vinylated products in good yields, with complete retention of the alkene configuration. The utility of the methodology is demonstrated by the diastereoselective synthesis of C-vinyl glycosides. Preliminary mechanistic studies suggest that the CÀ C bond formation is stereospecific and proceeds through a concerted radical coupling transition state.