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
the conversion was found to be not sensitive to the presence of air or atmospheric moisture. The methodology was found to be general and a wide variety of spiro 2,3-dihydroquinazolin-4(1H)-ones were prepared from 2-aminobenzamides and cyclic ketones within a few minutes in quantitative yields. The products isolated do not require any chromatographic purification. This method provides advantages such