Iron-catalyzed selective construction of indole derivatives via oxidative C(sp 3 )-H functionalization of indolin-2-ones.

Considering the importance of developing powerful catalysts and the pharmacophore characteristics of indole derivatives, we describe a switchable approach for the iron-catalyzed oxidative C(sp 3 )-H functionalization of indolin-2-ones. Selective transformations displayed excellent activity and chemoselectivity using FeCl 2 as the catalyst, air as the oxidant, and alcohol as the solvent. By manipulating the reaction conditions, particularly the choice of solvent, catalyst loading, and reaction sequence, a series of valuable indole derivatives, including isatins and symmetrical and nonsymmetrical isoindigos, were selectively synthesized in good to excellent yields. Furthermore, the gram-scale synthesis of compounds with biological anticancer activity under simple conditions highlights their great potential in practical applications.