A switch to vinylogous reactivity of vinyl diazo esters for the C–H allylation of benzamides by merging cobalt and photoredox catalysis

Herein, a de novo vinylogous reactivity of vinyl diazo esters in the C-H bond allylation of benzamides has been developed by coalescing cobalt and photoredox catalysis via C-H activation/allyl carbene migratory insertion. A close relationship between the high valent cobalt catalyst and the photocatalyst has been found to be crucial for this reactivity. The reaction uses oxygen as the sole oxidant and produces benign nitrogen as the only by-product. The reaction shows a good substrate scope with respect to both vinyl diazo esters and benzamides. The utility of the protocol is demonstrated through the late-stage functionalization of several bioactive molecules.