Synthesis and antimicrobial evaluation of 3-hydrazino-quinoxaline derivatives and their cyclic analoaues

A series of quinoxaline derivatives has been synthesized by reacting 3-hydrazinoquinoxalines 1a,b with many bifunctional reagents. Reaction of 1a,b with chloroacetyl chloride and ethyl chloroacetate afforded 1-chloromethyl[1,2,4]tnazoIo[4,3-a]quinoxalines 2a,b and dihydro[1,2,4]triazino[4,3-a]quinoxalin-2-ones 3a,b respectively. Condensation of 1a,b with ethyl acetoacetate and acetylacetone yielded 2-quinoxalinylhydrazonobutanoates 4a,b and 2-quinoxalinylhydrazono-2-pentanones 5a,b respectively. Cyclization of 5a,b gave 3,5-dimethylpyrazolylquinoxalines 6a,b. Moreover, reaction of compounds 2a,b with N-phenyl piperazine derivatives afforded 4-(4-Arylpiperazin-1-yl)-1-[(4-arylpiperazin-1-yl) methyl)]triazoloquinoxalines 7a−e. The prepared compounds were screened for in vitro antibacterial and antifungal activities. None of the tested compounds showed significant activity towards Pseudomonas aeruginosa. However, remarkable activities were noticed for compounds 5a and 5b against Eschenchia coli. Staphylococcus aureus and Candida albicans. Compounds 6a and 6b lacked any antimicrobial activities against the tested microorganisms