Capturing an Elusive [Cp*Co(Allyl)CO]+ Complex for Catalytic Allylic C─H Amidation of Unactivated Olefins.

Transition-metal-catalyzed nitrene transfer reactions offer a powerful strategy for direct C─H bond amination; however, the nature of the key reactive intermediates, particularly with Cp*Co(III) systems, remains elusive. Herein, we report a cobalt-catalyzed allylic C─H amidation of unactivated alkenes using dioxazolones as practical nitrene precursors. The isolation of a well-defined π-allyl-cobalt(III) complex provides a platform for direct interrogation of the reactive nitrene species. Mechanistic studies, including EPR spectroscopy and DFT calculations, support the involvement of an open-shell singlet cobalt-nitrenoid intermediate. Both the neutral cobalt(III) precatalyst and the synthesized π-allyl-cobalt(III) complex are catalytically active, and the catalytic system displays broad substrate scope, good functional-group tolerance, and moderate to high regioselectivity. These results provide key mechanistic insights into cobalt-mediated nitrene transfer reactions and establish a foundation for the development of selective cobalt-catalyzed C─H amination reactions.