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.