No abstract

The transformation of 1,2,3‐thiadiazolyl hydrazones of aldehydes and ketones including Dimroth rearrangement giving 1‐alkylidenamino‐5‐mercapto‐1,2,3‐triazoles, alkylation of mercapto group of these heterocyclic compounds by α‐bromoacetophenones and cyclization giving 6,7‐dihydro‐5H‐[1,2,3]triazolo[5,1‐b][1,3,4]thiadizines have been investigated. It was shown that the reaction for hydrazones of acetophenones and benzoaldehydes is diastereoselective. Triazolothiadiazine spiro derivatives were prepared with transformation of hydrazones of cyclic ketones.

It was shown that the reaction of 1,2,3-4-methoxybenzaldehyde tiadiazolyl hydrazona and α-bromo-4-methoxyacetophenone in the presence of triethylamine allowes 5-(4-methoxybenzoyl)-6-(4-methoxyphenyl)-6,7-dihydro-5H-[1,2,3]triazolo[5,1-b][1,3,4]thiadiazine as a mixture of cis- and trans-stereoisomers. The influence of nature of the solvent and temperature on the ratio of isomers was studied. An increase of the relative amount of the trans-stereoisomer with increasing polarity of the solvent is disclosed. It is noted that the temperature does not affect the ratio of isomers.