SYNTHESIS, ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES OF 1,3,5-THIADIAZINE DERIVATIVES

A series of N-(4-(benzyloxy)benzylidene)-2-(arylimino)-6-(phenylimino)-3,6-dihydro-2H-1,3,5-thiadiazin-4- amine derivatives (4a-d) have been synthesized by condensation of 1-(N-4-(benzyloxy) benzylidenecarbamimidoyl)-3-arylthiourea (3a-d) with phenyl isocyanodichloride. Interaction of 1- carbamimidoyl-3-arylthiourea (2a-d) and p-benzyloxy benzaldehyde yielded (3a-d). Monoacetyl (5b) and mononitroso (6b) derivatives were also synthesised by substitution of hydrogen atom of cyclic –NH- of 4b on treatment with acetic anhydride and sodium nitrite respectively. Further, 4b upon boiling with 5% aqueous ethanolic (1:1) sodium hydroxide solution underwent isomerisation into corresponding 4-(4- (benzyloxy)benzylideneamino)-6-(4-chlorophenylimino)-1-phenyl-5,6-dihydro-1,3,5-triazine-2(1H)-thione (7b). The structures of the newly synthesized 1,3,5-thiadiazine derivatives have been established on the basis of chemical transformations, elemental analysis and IR, 1H NMR, and Mass spectral studies. The zone of inhibition for some of the title compounds synthesized were determined against E. coli, S. aureus, B. thurengienesis and E. aerogenes and compared with Chloramphenicol as a reference drug. Some of the newly synthesized compounds showed moderate to high antimicrobial activity. Antioxidant activities of all the compounds were also determined. 4a, 4c and 4d were found to possess significant antioxidant activity. Keywords: Carbamimidoyl-3-arylthiourea, 1,3,5-thiadiazine, 1,3,5-triazine, antibacterial activity, antioxidant activity.