Synthesis and Antimicrobial Activity of Condensed and Uncondensed Quinoxalines

Abstract

Cyciocondensation of 2-chloro-3-substituted quinoxalines 4 with semicarbazide or phenylacetylhydrazine gave the corresponding l,2,4-triazolo[4,3-a]quinoxalines 5 and 6 . Reaction of 4 with sodium azide afforded tetrazolo[l ,5-a]quinoxalines 7. Heating of 2-hydrazino-3-substituted quinoxalines 9 with diethyl oxalate or acetic anhydride gave the corresponding 3-substituted-l,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-l 1-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.

Design, synthesis and biological evaluation of novel 1,2,4-triazolo and 1,2,4-triazino[4,3-a]quinoxalines as potential anticancer and antimicrobial agents

“…The structure of 7 was conrmed by IR and 1 H-NMR spectra and chemically through its parallel synthesis from 6 and acetic anhydride. 15 Cyclization of 6 using aromatic acids and phosphorus oxychloride yielded 1-aryl-4-benzyl-1,2,4-triazolo[4,3-a]quinoxaline 9a,b where 9a is reported to be differently prepared. 22 Compounds 14 and 15 were obtained by the reaction of 6 with formic acid and ethyl chloroformate, respectively.…”

“…22 Compound 15 was reported to be synthesized through the reaction of 2-chIoro-3-benzylquinoxaline with semicarbazide hydrochloride. 15 Compounds 16 and 17 were obtained by cyclization of 6 using succinic or phthalic anhydride, respectively, in glacial acetic acid. Furthermore reacting 6 with diethyl oxalate or diethyl malonate in boiling dry xylene gave compounds 18 and 19 respectively as described for the synthesis of analogous compounds.…”

“…The title compound was prepared by reuxing a solution of 3-benzyl-2-hydrazinoquinoxaline 6 (0.5 g, 2 mmol) in acetic anhydride (2.5 mL) for 2 h. The reaction mixture was poured onto ice water under stirring and the solid obtained was collected by ltration, washed with water and recrystallized from ethanol as yellowish needles (0.42 g, 76.6%), m.p. 182-183 C; reported m.p.176-178 C. 15 Method B. A mixture of 6 (0.5 g, 2 mmol) and 2-acetylbutyrolactone (0.28 g, 2.2 mmol) in dry xylene (5 mL) was reuxed for 3 h. The reaction mixture was cooled; the obtained crystalline product was ltered, dried, and recrystallized from ethanol to yield the desired compound (0.3 g, 54.8%).…”

“…14 The antimicrobial activity of the triazolo and triazinoquinoxalines is well documented. 10,11,[13][14][15] Lately the incorporation of 1,2,4-triazolo fused heterocycles in anti-proliferative and anti-microbial drug design projects revealed a very interesting scaffold to nd new potential agents. 16,17 These ndings prompted us to continue our investigations on quinoxalines having dual activity as anticancer and antimicrobial agents and to synthesize 1-substituted 4-benzyl-1,2,4-triazolo [4,3-a] in good yield, the product was identical to that previously described by Moffitt and Schultz obtained from the hydrolysis and decarboxylation of 3-(a-carboxamido)benzyl-2(1H)-quinoxalinone.…”

Crystal structure and Hirshfeld surface analysis of 2,4-diamino-6-phenyl-1,3,5-triazin-1-ium 4-methylbenzenesulfonate

“…Triazine derivatives have been found to possess a wide variety of biological activities such as anticancer (El-Gendy et al, 2001;Abdel-Rahman et al, 1999), antitumour (Menicagli et al, 2004) and anti-inflammatory (El-Massry et al, 1999) activities. In addition, many s-triazine derivatives have been found to exhibit antibacterial (Jyoti et al, 2003) and herbicidal activity.…”