Microwave-Assisted Base-Catalyzed Cyclization and Nucleophilic Substitution of O-Azidobenzanilides to Synthesize 1,2-Disubstituted Indazol-3-ones

A series of 1,2-disubstituted indazol-3-ones were synthesized by microwave-assisted base-catalyzed cyclization and nucleophilic substitution of o-azidobenzanilides. Among five tested reaction conditions, the cyclization of o-azidobenzanilides catalyzed by sodium hydride in DMF, sequentially followed by the nucleophilic substitution under microwave irradiation, exhibited the optimal results. Moreover, compared to the counterparts prepared by conventional heat, this method demonstrated a more expeditious and efficient process to establish a diversified 1,2-disubstituted indazol-3-one library for high-throughput biological screening.