Microwave-assisted synthesis of 1-aryl-1H-indazoles via one-pot two-step Cu-catalyzed intramolecular N-arylation of arylhydrazones

摘要

A highly efficient one-pot two-step microwave procedure was developed for the synthesis of 1-aryl-lH-indazoles.Microwave heating of 2-halobenzaldehydes or 2-haloacetophenones with phenylhydrazines at 160 deg C for 10 min quantitatively yielded the arylhydrazones,which were further cyclized to give 1-aryl-lH-indazoles via Cul/diamine-catalyzed N-arylation under microwave heating(160 deg C,10 min).Good to excellent yields were observed for 2-iodo,2-bromo,and 2-chloro benzaldehydes or acetophenones.