Visible Light Enables NHC–Nickel-Mediated Carbonyl Deletion from Carboxamides

Electron-rich N -heterocyclic carbene- (NHC-) supported nickel complexes are prized for their reactivity with weak polar functional groups, especially acyl electrophiles. However, synthetic applications leveraging this potent nucleophilicity have been limited to reactivity on the ground-state energy surface, thereby constraining the feasibility of downstream mechanistic steps. Herein, we report the development of a light-driven, NHC-nickel-mediated transformation that takes advantage of the complementary strengths of ground- and excited-state reactivity of NHC-nickel complexes. The carbonyl-deletion protocol enables intramolecular N -arylation from readily accessible carboxamides for the synthesis of di- and triaryl amines under mild conditions (ambient temperatures, additive-free). Combined density functional theory, organonickel intermediate isolation, single-crystal X-ray diffraction, spectroscopy, and radical-probe experiments reveal the origins of substrate-dependent reactivity and the role of light in C–N bond formation. The results support a dinuclear pathway for decarbonylation followed by photoinduced Ni–aryl bond weakening and in-cage C–N-forming radical rebound. These findings establish a mechanistic framework for developing direct photochemical reactivity from electron-rich NHC–nickel complexes relevant to organic synthesis.