Synthesis and antimicrobial evaluation of some new polyheterocyclic systems containing 1,2,4-triazine moiety

7-(4-Chloro/3-nitrophenyl)-8-[5,6-diphenyl-4-(1,3-thiazol-2-yl)-1,4-dihydro-1,2,4-triazin-3-yl]-5-oxo-1,5-dihydro[1,2,4]triazolo[1,5-a]pyridine-6-carbonitrile (6a, b) was utilized as a key intermediate for the target polyheterocyclic systems. Reactions of 6a, b with halocarbonyl reagents followed by heterocyclization with bi-nitrogen nucleophiles gave some new nitrogen heterocycles (7-13). Structures of the new compounds were established by elemental analyses and spectral data. The synthesized compounds were screened for their antimicrobial activity.