Cobalt-Catalyzed Oxidative Cyclization of Benzamides with Maleimides: Synthesis of Isoindolone Spirosuccinimides

The oxidative cyclization of substituted benzamides with maleimides assisted by 8-aminoquinoline in the presence of a catalytic amount of Co­(OAc)2·4H2O provides isoindolone spirosuccinimides in good to excellent yields. The cyclization reaction was compatible with various substituted benzamides and maleimides. A possible reaction mechanism involving the C–H bond activation as a key step was proposed. The competition experiment and deuterium labeling studies were performed to investigate the mechanism of the reaction.