Collect. Czech. Chem. Commun. 1988, 53, 626-632

Synthesis and cyclization of some N-oxides of 2-pyridylhydrazones of mesoxalic acid derivatives

Jan Slouka and Vojtěch Bekárek

Department of Analytical and Organic Chemistry, Palacký University, 771 46 Olomouc


Coupling of diazotized 2-aminopyridine-1-oxide with ethyl cyanoacetylcarbamate, cyanoacetamide, malononitrile, and 2-benzimidazolylacetonitrile in an acid medium afforded N-oxides of the corresponding 2-pyridylhydrazones Ia-Id, which also exist in the N-hydroxyazine tautomeric forms IIa-IId as confirmed by IR spectroscopy. Hydrazone Ia was thermally cyclized to give 2-(pyridine-1-oxide-2-yl)-3,5-dioxo-2,3,4,5-tetrahydro-1,2,4-triazine-6-carbonitrile (IIIa) which was converted into the corresponding thioamide IIIb, acid IIIc, and amidoxime IIId.