Regioselective Introduction of Indolin-3-one Moieties to Substituted Heteroaromatic Compounds

C2-substituted indolin-3-ones are formed via a mild dual catalytic method involving the generation of a reactive <i>C</i>-acylimine species that can be intercepted by a variety of nucleophilic arenes. The transient <i>C</i>-acylimine electrophile could be trapped regioselectively by a variety of arenes, on which the most reactive site was blocked, offering a new scope of products. Competition experiments show that the <i>C</i>-acylimine electrophile exhibits selectivity for pyrrole over other heteroaromatic traps. Indolin-3-one functionalization of melatonin, protected amino acids, and dipeptides showcases the potential of this chemistry for late-stage diversification of biomolecules containing electron-rich arene units.