One-pot Synthesis of Oxindoles through C−H Alkylation and Intramolecular Cyclization of Azobenzenes with Internal Olefins

The rhodium(III)-catalyzed site-selective C−H alkylation of azobenzenes and internal olefins, such as maleimides, maleates and fumarates, followed by reductive intramolecular cyclization is described. A cationic rhodium catalyst in the presence of acetic acid additive in dichloroethane solvent was found to be the optimal catalytic system for the construction of ortho-alkylated azobenzenes, which smoothly underwent the intramolecular cyclization leading to the formation of C3-functionalized oxindoles in the presence of zinc powder and acetic acid. The formed oxindole scaffold could be an important asset towards the development of novel bioactive compounds. (Figure presented.).