Synthesis of Nitrogen Functional Derivatives of 5-substituted-6-azauracil as one of the Four Nucleobases in the Nucleic Acid of RNA

3-Arylhydrazono-2,4-dioxo-4-phenylbutanoateshave been prepared by the coupling of benzoylpyruvate with aryldiazonium chlorides.Reactions ofthe 3-arylhydrazono-2,4-dioxo-4-phenylbutanoateswith 1-aminoguanidine, semicarbazide, and thiosemicarbazidegave5-substituted 2-imino-6-azauracil (3a),6-azauracil (3b), and 2-thio-6-azauracil (3c), respectively. The analytical data of these compounds - IR, 1H, and 13C NMR spectral data - are reported.