Synthesis and Biological Activity of 2,3-Bis-(2-Oxoylidene)-1,2,3,4-Tetrahydroquinoxalines

Condensation of alkylmethylketones with diethyl oxalate and 1,2-diaminobenzene yielded 2,3- bis -(2-oxoylidene)-1,2,3,4-tetrahydroquinoxalines ( II – IV ). Four isomeric species were identified using spectral methods. Structural features of the synthesized compounds were discussed. The biological activity of the obtained compounds was investigated. It was observed that the synthesized compounds had low toxicity. It was found that (1 Z ,1′Z)-1,1′-(1,4-dihydroquinoxaline-2,3-diylidene)dibutan-2-one ( II ) exhibited antinociceptive activity that was greater than that of metamizole sodium. The antioxidant activity in an Escherichia coli BW 25113 oxidation resistance model in the presence of H 2 O 2 solution (3 mM) was also most pronounced for II whereas V had pro-oxidant activity. The compounds showed high antiradical activity for diphenylpicrylhydrazyl (DPPH) binding that was comparable with that of trolox.