Synthesis of some derivatives of imidazo[1,2-a]pyridine,pyrazolo[1,5-b]imidazole,and 4-(3H)quinazolinone from α-ketohydrazidoyl bromides

α-Aroyl-N-arylhydrazidoyl bromides 1 react with 2-aminopyridine in ethanol and give 2-aryl-3-arylazo-imidazo1,2-α]pyridines 2 in 60-75% yield. The reaction of 1 with 3-phenyl-5-aminopyrazole in ethanol leads to 2,6-diaryl-3-arylazo-1H-pyrazolo1,5-b]imidazoles 3 in almost quantitative yield. Also, 1 react with anthran-ilic acid in the presence of triethylamine giving 3-arylamino-2-aroyl-4-(3H)quinazolinones 4 in 80-85% yield. The structures of the products were assigned and confirmed on the basis of their elemental analysis and electronic absorption, infrared and nmr spectra.