In this study, some of five membered and fused heterocyclic derivatives containing 1,2,4- Triazole, 1,3,4- Thiadiazole and triazolo [3,4-b] thiadiazine were synthesized by several cyclization steps.2, 5-dimercapto-1, 3, 4-thiadiazole [A1] was obtained by the reaction of hydrazine hydrate with carbon disulfide. Compound [A1] was reacted with Ethyl chloro acetate in presence of alkali ethanol to give 2, 5-bis (thioethylacetate 2, 2', diyl)1,3,4 thiadiazole [A2]. 2, 5-bis (thioacetiohydrazide-2-yl) - 1, 3, 4 -thiadiazole [A3] was obtained from the reaction of compound [A2] with hydrazine hydrate. bis-potassium dithiocarbazinate [A4] was obtained by reacting of compound [A3] with CS2 in alkali ethanol. 2,5-bis(4-amino-3-thiol-5-thiomethyl-1,2,4 triazole-5,5'yl)- 1,3,4-thiadizole [A5] was obtained by the cyclization reaction of compound [A4] with hydrazine hydrate. The last step in this study involved preparation of 2,5-bis((6-(4-bromophenyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl- thiomethyl) -1,3,4-thiadiazole [A6] by the cyclization reaction of compound [A5] with p-Bromo phenacylbromide.Compounds 5, 5'-methylene bis-(4-amino-4H-1,2,4-triazole-3-thiol) [B3], bis (6-(4-bromophenyl)-7H-[1,2,4]triazolo[3,4 b][1,3,4]thiadiazin-3-yl)methane [B4], 4[amino]-5-phenyl-4H-1, 2, 4-triazole-3-thiol [C3] and 6- ( 4-bromophenyl ) - 3-phenyl - 7H - [1,2,4] triazolo[3,4-b] [1,3,4] thiadiazine [C4] were synthesized by the same chemical reactions as these were used in the synthesis of compounds [A5] and [A6] using Ethyl Maolnate and Methyl Benzoate as starting materials instead of compound [A2].The biological activity of compounds [A5], [A6], [B3], [B4], [C3] and [C4] were studied against four types of bacteria, (two of them were gram negative (Escherichia Coli and Klepsiala pneomonia), the others were gram positive (Staphylococcus Aureus and Enterococcus Faecalis). The fungus Candida Albicans was used in the antifungal study.The results showed that most of these compounds have a high biological activity as antibacterial and antifungal agent against these types of microorganisms in comparison with the standard antibiotics and antifungal (Ceftriaxone, Amoxicillin and Fluconazole) as references.
