2-Chloroaniline (I) is diazotized with NaNO2/HCl and the resultant diazonium salt (II) is further coupled to 2,4-pentanedione (III) to furnish the diketo hydrazone (IV). Subsequent bromination of (IV) with Br2 in Ac2O/AcOH gives rise to the hydrazonyl bromide (V). This is finally condensed with 3-ethynylaniline (VI) in DMF to provide the corresponding aryl amidrazone.