1,2,4-Triazine and triazole derivatives from α-keto acids and thiosemicarbazides

Thiosemicarbazides of 2-hydroxyphenylglyoxylic acid, which, depending on the conditions, undergo cyclization to interconvertible 5-(2-hydroxyphenyl)-6-oxo-1,2,4-triazine-3-thiones or (2-hydroxy-benzoyl)-²-1,2,4-triazoline-5-thiones, are formed by the action of thiosemicarbazide and its homologs on coumarindione. The thiosemicarbazones of 2-hydroxyphenylglyoxlyic and other 2-substituted phenylglyoxylic acids undergo cyclization to 6-(2-hydroxyphenyl)-5-oxo-1,2,4-triazine-3-thiones.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp, 116–121, January, 1977.     

Semicarbazones and thiosemicarbazones of the heterocyclic series

IsatinΒ-thiosemicarbazone and its alkyl derivatives containing a hydrogen atom attached to N_(2′) exist primarily in the form of the syn isomer stabilized by intramolecular hydrogen bonding in solutions and in the crystalline state. The strength of this hydrogen bond increases when both hydrogen atoms in the primary thioamide group are replaced by alkyl groups.     

Semicarbazones and thiosemicarbazones of the heterocyclic series

Isatin 2-thioxohydrazones formed in the reaction of isatin O-methyl ether with thioxohydrazines can be isolated in iminohydrazine and aminohydrazone tautomeric forms. The effect of the structure of the hydrazone fragment and the medium on the interconversions of the tautomers was investigated.See [1] for communication 42.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 355–359, March, 1979.     

Semicarbazones and thiosemicarbazones of the heterocylic series XXXVIII. Aminohydrazone-iminohydrazine tautomerism of isatin 2-thiosemicarbazone and its alkyl derivatives

Isatin 2-thiosemicarbazone and its derivatives with one methyl group attached to the nitrogen atoms of the side chain exist in solution primarily in the iminohydrazine tautomeric form. Further substitution of the hydrogen atoms attached to the nitrogen atom in the primary thioamide group or replacement of the hydrogen atom attached to the sulfur atom by a methyl group promotes the formation of the aminohydrazone tautomer.See [1] for communication XXXVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 83–88, January, 1976.