Efficient Synthesis of 3-Substituted Indazoles Using Pd-Catalyzed Intramolecular Amination Reaction of N-Tosylhydrazones

The efficient method for the preparation of 3-substituted indazoles was developed using the palladium catalyzed intramolecular amination reaction of 2-bromophenyl hydrazone derivatives. Good functional group compatibility was observed under mild reaction conditions and various 3-substituted indazoles were obtained in moderate to excellent yield.