Cupraelectro-Catalyzed Alkyne Annulation: Evidence for Distinct C–H Alkynylation and Decarboxylative C–H/C–C Manifolds

Synthetically meaningful isoindolones were accessed by cupraelectro-catalyzed C–H activation with electricity as terminal oxidant. Thus, a versatile, inexpensive, and nontoxic Cu­(OAc)2 catalyst enabled broadly applicable C–H/N–H functionalizations on electron-rich and electron-deficient benzamides with distinct functional group tolerance and resource-economy. Detailed mechanistic studies provided strong support for a C–H alkynylation mechanism through fast C–H metalation, which likewise set the stage for cupraelectro-catalyzed C–H/C–C functionalizations in a decarboxylative fashion.