Synthesis of Fused Heterocycles Based on 1-Amino-1H-tetrazole-5-thiol and α,β-Unsaturated Aldehydes

8-Phenyltetrazolo[5,1- b ][1,3,4]thiadiazepine was obtained as a result of intermolecular cyclization of 1-amino-1 H -tetrazole-5-thiol and 3-phenyl-2-propynal. The reaction of α-bromocinnamaldehyde with 1-amino-1 H -tetrazole-5-thiol led to the formation of 7-benzylidene-7 H -tetrazolo[5,1- b ][1,3,4]thiadiazine. An effective method was developed for the synthesis of 1-[(3-phenylprop-2-yn-1-yl)amino]-1 H -tetrazole-5-thiol, a key intermediate in the possible synthesis of 7-benzylidene-6,7-dihydro-5 H -tetrazolo[5,1- b ][1,3,4]thiadiazine.