Synthesis and antibacterial properties of new N<sub>4</sub>-acetylated hexahydro-2,7-dioxopyrido[2,3-<i>f</i>]quinoxaline-8-carboxylic acids
作者:Yusuf M. Al-Hiari、Ashok K. Shakya、Muhammed H. Alzweiri、Tariq M Al-Qirim、Ghassan Shattat、Mustafa M. El-Abadelah
DOI:10.3109/14756366.2010.543421
日期:2011.10.1
Direct interaction between 7-chloro-1-cyclopropyl-6-fluoro-8-nitro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid and primary alpha-amino acids (exemplified by glycine, alanine, and l-valine) in aqueous ethanolic NaHCO3 at 70-80 degrees C for 24-72 h produced the respective N-(4-oxoquinolin-7-yl)-alpha-amino acids (6a-c). The latter derivatives underwent reductive lactamization upon treatment with Na2S2O4 in aqueous ethanol to afford moderate yields of the corresponding pyrido[2,3-f]quinoxaline-8-carboxylic acids (8a-c). Acetylation of 8a-c using acetyl chloride afforded N-4-acetylated hexahydro-2,7-dioxopyrido[2,3-f] quinoxaline-8-carboxylic acids (9a-c). The structures, assigned to these new heterocyclic products, are supported by analytical and spectral data. The synthesized compounds (6a-c/9a-c) showed appreciable antibacterial activity as compared with ciprofloxacin.