New Approaches for the Synthesis of 1,3,4-Thiadiazole and 1,2,4-Triazole Derivatives with Antimicrobial Activity

The thiosemicarbazide derivatives 3a and 3b were cyclized in the presence of concentrated sulfuric acid to give the 5-cyanomethyl-1,3,4-thiadiazole derivatives 4a and 4b , respectively. The latter products were used for many heterocyclic transformations to form coumarin, 1,3,4-thiadiazolo4,5-a]pyridine, and 5-thiophenylthiophene. In addition, compound 3b underwent cyclization in NaOH (2 N) solution to give the 1,2,4-triazole derivative 16 . The reactivity of the latter product towards some chemical reagents was studied. The antimicrobial activities of the newly synthesized products were measured and showed high activities.