Microwave-assisted Solvent-free Synthesis and in Vitro Antibacterial Screening of Quinoxalines and Pyrido[2, 3b]pyrazines

Abstract

Abstract:We report herein the microwave assisted synthesis, without solvents and catalysts, of 6-substituted quinoxalines and 7-substituted pyrido [2,3b]pyrazines. The compounds were obtained in good yields and short reaction times using the mentioned procedure and two new structures are reported. A complete 1 H-and 13 C-NMR assignment was performed using 1D and 2D-NMR. Additionally, an in vitro screening was performed on Gram-positive and Gram-negative bacteria using amoxicillin as positive reference. Compounds bearing a pyridyl group tended to have higher antibacterial activity, but the best activity against Bacillus subtilis and Proteus mirabilis was observed with quinoxaline derivatives.

In Vitro and In Vivo Activities of 2,3-Diarylsubstituted Quinoxaline Derivatives against Leishmania amazonensis

“…Several biological effects have been reported, including anticancer (14,16,17), antimicrobial (18)(19)(20)(21)(22), antiviral (23), and anti-inflammatory and antioxidant (24,25) effects.…”

Present status of quinoxaline motifs: Excellent pathfinders in therapeutic medicine

“…General sensitivity testing on a series of hydrazones, revealed 77 to be the most promising with widest zone of inhibition [90]. Bacteriostatic activity of other quinoxaline derivatives 78 [91], 79 [92], 80 [93], 81 [94] and 82 [95] had been reported. Further studies also established that steroidal-based oxazoloquinoxalines 83 [96a] and its thiazolo-counterpart 84 [96b] were better antibacterial agents than the standard drug amoxicillin and chloramphenicol respectively [96].…”

Indion 190 resin: Reusable catalyst for the synthesis of quinoxalines and pyrido-pyrazines at ambient temperature

“…A variety of quinoxalines and pyrido-pyrazines (Table 3) have been synthesized in good yields ranging from 97 to 83% irrespective of the complexities and different substituted functionalities. All the synthesized products are known and reported in the literature [11,29,30]. …”

“…Commonly employed method involves condensation of an aryl-1,2-diamine with a 1,2-dicarbonyl in refluxing ethanol or acetic acid for 2-12 h yielding 34-85% of product [10]. Several improved methods reported in the literature for the synthesis of quinoxalines include microwave synthesis [11], the use of PEG-400 [12], RuCl-(PPh3)3-TEMPO [13], CAN [14], CuSO4.5H2O [15], SA/MeOH [16], montmorillonite K-10 [17], InCl3 [18], Zn/proline [19], Ga(OTf)3 [20], HClO4-SiO2 [21], -cyclodextrins in water [22], FeMAP [23], TiO2-P25 [24], ZnO-beta zeolite [25], silica-supported antimony(III) chloride [26] as catalysts.…”