Visible-light-induced dual catalysis for -α C(sp)-H amination and alkenylation of -alkyl benzamides.

The amination and alkenylation of the C(sp)-H bond at the -α position of secondary benzamides were both realized in this work by using -hydroxyphthalimide (NHPI) imidate esters as substrates under a dual catalysis involving a photoredox catalyst and hydrogen atom transfer (HAT) catalyst. The developed methods significantly extended the scope of applications of the -α position C(sp)-H bond functionalization with regard to secondary -alkylamides. More importantly, new reaction models in photoredox catalysis have been established. Based on corresponding experiments and density functional theory (DFT) calculations on the critical reaction steps combined with information reported previously, we proposed a synergistic photo- and organocatalytic reaction process for the C(sp)-H bond functionalization and also clarified the occurrence of a chain process in the reaction pathway.