Iron-Catalyzed Oxidative Coupling of Indoline-2-ones with Aminobenzamides via Dual C-H Functionalization.

We describe an unprecedented dual C-H functionalization of indolin-2-one via an oxidative C(sp3)-H/N-H/X-H (X = N, C, S) cross-coupling protocol, which is catalyzed by a simple iron salt under mild and ligand-free conditions and employs air (molecular oxygen) as the terminal oxidant. This method is readily applicable for the construction of tetrasubstituted carbon centers from methylenes and provides a wide variety of spiro N-heterocyclic oxindoles.