New Heterocyclic Compounds from 1,3,4-Thiadiazole,1,3,4-Oxadiazole and 1,2,4-Triazole Class with Potential Antibacterial Activity

摘要

In this paper new heterocyclic compounds from 2-amino-1 ,3,4-thiadiazole, 2-amino-1,3,4-oxadiazole and 1,2,4-triazol-3(4H)-thione class were obtained from acylthiosemicarbazide 2 by intramolecular cyclization in different conditions. In the reaction of 4-(4-bromophenylsulfonyl)-benzoic acid hydrazide 1 with 4-fluorophenyl isothiocyanate, the new 1-[4-(4-bromophenylsulfonyl)benzoyl]-4-(4-fluorophenyl)-thiosemi-carbazide 2 was obtained. 5-(4-(4-Bromophenylsulfonyl)phenyl)-N-(4-fluorophenyl)-1,3,4-thiadiazol-2-amine 3 was prepared by the intramolecular cyclization of acylthiosemicarbazide 2 in concentrated sulphuric acid media. 5-(4-(4-Bromophenylsulfonyl)phenyl)-N-(4-fluorophenyl)-1,3,4-oxadiazol-2-amine 4 was obtained from reaction of acylthiosemicarbazide 2 with HgO, in alcoholic media, or with I2/KI, in basic media. The synthesis of 5-(4-(4-bromophenylsulfonyl)phenyl)-4-(4-fluorophenyl)-2H-1,2,4-triazole-3(4H) 5 was carried out by cyclodehydration of acylthiosemicarbazide 2 in sodium hydroxide media. Alkylation of 1,2,4-triazole 5 with ethyl bromoacetate afforded S-substituted 1,2,4-triazole 6. Acylation of same 1,2,4-triazole 5 with acetyl chloride led to the N-substituted 1,2,4-triazole 7. The structures of these new compounds were elucidated by FTIR, UV-Vis, ~1H-NMR, ~(13)C-NMR, MS spectra and elemental analysis. All the new compounds were screened for their antibacterial activity against 11 type strains of different species of oral streptococci.