I. V. Lagoda

Tautomerism and conformational isomerism of mercaptoacetylhydrazones of aliphatic and aromatic aldehydes

Mercaptoacetylhydrazones of aliphatic and aromatic aldehydes exist in the solutions as tautomeric mixtures of open-chain and cyclic 1,3,4-thiadiazine forms. The linear hydrazone form consists of a set of isomers due to the configurational and conformational isomerism. At growing bulk of the alkyl substituent at the C=N bond of the aliphatic aldehydes derivatives decreases the fraction of the cyclic tautomer; therewith the logarithms of the constants of the chain-ring tautomeric equilibrium correlate with the steric constants of the alkyl substituents. In the series of the aromatic aldehydes mercaptoacetylhydrazones the linear tautomer prevails, and the equilibrium position is insignificantlyt affected at variation of the electronic characteristics of the substituents in the aromatic ring.

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.

Ring-chain tautomerism of 2-aryl-6-oxohexahydropyrimidine-4-carboxylic acid sodium salts

It was shown by 1H and 13C NMR spectroscopy that the 2-aryl-6-oxohexahydropyrimidine-4-carboxylic acid sodium salts existed in D2O solution as a tautomeric mixture of cyclic and linear forms. The cyclic form consisted of two (2RS,4S)-stereoisomers, differing in the aryl substituent configuration at the pyrimidine ring C-2 atom.

Structure of products of aldoses condensation with thioglycolic acid hydrazide

Condensation products of thioglycolic acid hydrazide with aldoses (L-arabinose, D-xylose, L-rhamnose, D-galactose, D-glucose, D-mannose) exist in the D2O solution as a tautomeric mixture of α,β-pyranose form and six-membered 1,3,4-thiadiazine form present as two diastereomers.

Structure of aldose condensation products with 2-hydroxyand 2-sulfanylbenzohydrazides

The structure of the condensation products of 2-hydroxy- and 2-sulfanylbenzohydrazides with a series of aldoses (L-arabinose, D-ribose, L-ramnose, D-galactose, D-glucose, D-mannose) was studied by 1H and 13C NMR spectroscopy. The condensation products of monosaccharides with 2-hydroxybenzohydrazide in DMSO-d6 solution exist as equilibrium mixtures of linear hydrazone and cyclic pyranose and furanose forms, the cyclic tautomers being represented by two stereoisomers (α- and β-anomers). The aldose condensation products with 2-sulfanylbenzohydrazide in the crystalline state have cyclic 1,3,4-benzothiadiazepine structure, while in DMSO-d6 solution they undergo complete or partial isomerization into cyclic pyranose tautomer.

Condensation Products of D-Ribose with Thiol-Containing Hydrazides and Gold Glyconanoparticles Thereof

The accessible D-ribose mercaptoacetyl-, 3-mercaptopropionyl-, and 2-mercaprobenzoylhydrazones were used to develop a method of synthesis of gold glyconanoparticles with the average particle diameter of 10–40 nm and a low polydispersity index.

Synthesis and structure of (2S,4S)-2-alkyl(aryl)-3-(3-sulfanylpropanoyl)-6-oxohexahydropyrimidine-4-carboxylic acids

Proceeding from natural amino acid L-asparagine and commercially available aldehydes a stereoselective synthesis was developed of (2S,4S)-2-alkyl(aryl)-3-(3-sulfanylpropanoyl)-6-oxohydropyrimidine-4-carboxylic acids, potential antihypertensive drugs, inhibitors of the angiotensin converting enzyme.

Synthesis of Silver Glyconanoparticles Based on 3-Thiopropionylhydrazones of Mono- and Disaccharides

A method of synthesis of silver glyconanoparticles with average particle size 15–40 nm and low polydispersity index based on available 3-thiopropionylhydrazones of mono- and disaccharides has been elaborated. The prepared compounds have exhibited high antifungal, antibacterial, and antiviral activity and are promising for further comprehensive study.

SYNTHESIS OF 2-SUBSTITUTED (2R,4R)-3-(3-MERCAPTO- PROPIONYL)THIAZOLIDINE-4-CARBOXYLIC ACIDS

The natural amino acid L-cysteine, commercially available aldehydes, and 3-(acetylsulfanyl)propionyl chloride were used for the synthesis of 2-substituted (2R,4R)-3-(3-mercaptopropionyl)thiazolidine-4-carboxylic acids, potential antihypertensive drugs with angiotensin converting enzyme inhibiting action.

Structure of the Condensation Products of D-Lactose and D-Maltose with SH-Contaning Carboxylic Acid Hydrazides

The structure of the condensation products of D-lactose and D-maltose with sulfanylacetic, 3-sulfanylpropanoic, and 2-sulfanylbenzoic acid hydrazides has been studied 1H and 13C NMR spectroscopy. The condensation products obtained from the disaccharides and sulfanylacetohydrazide and 3-sulfanylpropanehydrazide have pyranose structure in the crystalline state, whereas those derived from 2-sulfanylbenzohydrazide have cyclic 1,3,4-benzothiadiazepine structure in crystal. All condensation products in solutions in most solvents (D2O, DMF-d7, DMSO-d6) exist as equilibrium mixtures of linear and cyclic pyranose and 1,3,4-benzothiadiazepine tautomers.