S. M. Shevchenko

Ring-chain tautomerism of substituted hydrazones. 18. Synthesis of 2-hydrazino-1-propanethiol and structure of its alkylidene derivatives

Abstract1-Aminoaziridines react with hydrogen sulfide with ring opening to give vic-hydrazino thiols. In the case of 1-amino-2-methylaziridine the reaction proceeds regioselectively with the formation of 2-hydrazino-1-propanethiol. The products of condensation of the latter with carbonyl compounds exist in solution, depending on their structure, in the form of the corresponding perhydro-1,3,4-thiadiazines, (2-mercapto-1-methylethyl)hydrazones, or tautomeric mixtures of these compounds. The thermodynamic parameters of the tautomeric equilibria were determined for several systems from the 1H NMR spectra.

Ring-chain tautomerism of substituted hydrazones. 17. Alkyl-substituted perhydro-1,3,4-thiadiazines

It was demonstrated by PMR spectroscopy that alkylidene derivatives of vic-(Nalkylhydrazino) thiols in solutions exist exclusively in the cyclic form, i.e., as perhydro-1,3,4-thiadiazines. Only pinacolone derivatives undergo reversible isomerization to the corresponding hydrazones. The thermodynamic parameters of the ring-chain equilibria were determined. The static stereochemistry and the dynamics of the conformational transitions of perhydro-1,3,4-thiadiazines are discussed.