Thiosalicyloylhydrazones of aliphatic aldehydes and their cyclization to give 1,3,4-benzothiadiazepine derivatives

¹H and ¹³C NMR spectroscopy showed that the previously unknown thiosalicyloylhydrazones of aliphatic aldehydes, 2-HSC₆H₄CONHN=CHAlk (Alk = Me, Et, Pr, Bu, i-Pr, i-Bu) exist in solution as a tautomeric mixture of the linear and cyclic 1,3,4-benzothiadiazepine forms. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 460–464, March, 2008.     

Structure of the condensation products of 3-sulfanylpropionic acid hydrazide with aldehydes,ketones, and aldoses

Condensation products of aliphatic aldehydes with 3-sulfanylpropionic acid hydrazide exist in solution as mixtures of linear hydrazone and cyclic 1,3,4-thiadiazepine tautomers. Hydrazones derived from 3-sulfanylpropionic acid hydrazide and aromatic aldehydes and ketones have mostly linear structures of different stereoisomers arising from Z-E isomerism with respect to the double C=N bond and restricted rotation about the C(O)-N bond. Condensation products of 3-sulfanylpropionohydrazide with a series of aldoses give rise to ring-chain-ring tautomeric equilibrium between α,β-isomeric pyranose structures, open-chain aldose hydrazone tautomer, and two diastereoisomeric seven-membered cyclic 1,3,4-thiadiazepine forms.     

1,2,4-Triazines – products of reaction of thiocarbohydrazide and its alkyl(aryl)-substituted derivatives with 1,2-dicarbonyl compounds

The reaction of a series of 1,2-dicarbonyl compounds with thiocarbohydrazide and its 1- and 1,4-alkyl-(aryl)-substituted analogs has been studied. Treatment of diacetyl with the polynucleophiles indicated gives monohydrazones and/or 5-methylene-4,5-dihydro-2H-[1,2,4]triazine-3-thiones. Reaction of phenylglyoxal and benzil with thiocarbohydrazide yields 5-hydroxy- or 5-alkoxy-4,5-dihydro-2H-[1,2,4]triazine-3-thiones depending on the nature of the solvent. The products of condensation with 1,1-dimethylthiocarbohydrazide showed a thiocarbonohydrazone – 5-hydroxy-4,5-dihydro-2H-[1,2,4]tri-azine-3-thione ring-chain type equilibrium.     

Structure of asymmetric 5-hydrazino-2-pyrazolines

NMR (¹H and ¹³C) spectroscopy was used to show the existence of ring-ring tautomers for 5-hydrazino-2-pyrazolines with asymmetric structure and the predominant formation of cis-isomers for 4-substituted compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1358–1361, October, 1988.