Palladium-catalyzed cyclization of arylhydrazones of 2-bromoaldehydes and 2- bromoacetophenones to give 1-aryl-1 H-indazoles has been studied in detail. The cyclization of arylhydrazone of 2-bromobenzaldehydes can be performed with good to high yields using Pd (dba) 2 and chelating phosphines, of which the most effective are rac- BINAP, DPEphos, and dppf, in the presence of Cs2CO3 or K3PO4 as a base. Electron-rich ...