Intramolecular C–H Nitrene Insertion Catalyzed by Single‐Atom Cobalt on Nitrogen‐Doped Carbon

ABSTRACT Single‐atom catalysts (SACs) are advancing heterogeneous organic synthesis by combining the molecular precision of homogeneous complexes with the reusability of solid materials. We developed a cobalt SAC that mediates the intramolecular C(sp 3 )–H nitrene insertion. The catalyst converted arylsulfonyl azides into benzosultams, with dinitrogen as the only stoichiometric byproduct. The solid catalyst can be recovered by simple centrifugation and reused for 17 consecutive cycles (cumulative TON = 340) without cobalt agglomeration.