The synthesis of triazolothiadiazines and thiadiazoles from 1,2-bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl)-ethanol and ethane

The reaction of DL-malic and succinic acids with thiocarbohydrazide afforded 1,2bis-{[}4-amino-5-mercapto-1,2,4-triazol-3-yl]-ethane derivatives 3a and 3b. The reaction of 3a,b with phenacyl bromide and benzoin afforded 1,2-bis-1,2,4-triazolo {[}3,4-b]{[}1,3,4] thiadiazine derivatives 4 and 5. The carboethoxymethylation of 3a and 3b gave 6a and 6b, respectively, and their reactions with carbon disulfide and benzoylisothiocyanate gave the 1,2-bis-1,2,4-triazolo{[}3,4-b]{[}1,3,4] thiadiazole 7 and 9, and with p-nitrobenzaldehyde gave a Schiff's base and dihydrothiadiazole 8. The structures were confirmed by using (1)H and (13)C NMR spectra. Selected members of these compounds were screened for antimicrobial activity.