Synthesis and antimicrobial activity of condensed and uncondensed quinoxalines

Cyclocondensation of 2-chloro-3-substituted quinoxalines 4 with semicarbazide or phenylacetylhydrazine gave the corresponding 1,2,4-triazoto[4,3-a]quinoxalines 5 and 6. Reaction of 4 with sodium azide afforded tatrazolo[1,5-a]quinoxalines 7. Heating of 2-hydrazino-3-substituted quinoxalines 9 with diethyl oxalate or acetic anhydride gave the corresponding 3-substituted-1,2,4-triazolo[4,3-a]quinoxalines 12 and 13 respectively. The 2-pyrazolylquinoxaline derivatives 14 were also obtained when 9 was heated with acetylacetone. 3-Benzyl-4-oxo-11-substituted-1,2,4-triazino[4,3-a]quinoxalines 16 were obtained upon cyclization of hydrazones 15 with phosphoryl chloride. The prepared compounds were evaluated for antibacterial and antifungal activity.