Synthesis of 2,3-dihydro-1H-indazoles by Rh(iii)-catalyzed C–H cleavage of arylhydrazines

A rhodium-catalyzed efficient method for the synthesis of 2,3-dihydro-1H-indazoles is described. The reaction of arylhydrazines with olefins results in the corresponding 2,3-dihydro 1H-indazoles with exclusive regioselectivity via C–H bond activation. The utility of the methodology is illustrated by a rapid synthesis of 1H-indazoles under mild reaction conditions in half an hour.