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

ABSTRACT

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.