alpha,alpha-DIBROMOKETONES AS USEFUL PRECURSORS IN ORGANIC SYNTHESIS: A SIMPLE AND EFFICIENT SYNTHESIS OF 2,4-DIARYL-1,2,3-TRIAZOLES VIA OXIDATIVE CYCLIZATION OF BISPHENYLHYDRAZONES

alpha,alpha-Dibromoacetophenones (1a-1f) on reaction with phenylhydrazine afford corresponding arylglyoxal bisphenylhydrazones (2a-2f). The oxidation of bishydrazones 2a-2f by using copper(II) chloride in acetic acid leads to intramolecular cyclization with the formation of 2,4-diaryl-1,2,3-triazoles (3a -3f). The method for the conversion 1 -> 3 has been simplified by developing one-pot procedure without isolation of intermediates 2.