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.