Journal of Enzyme Inhibition and Medicinal Chemistry 2011-10-01

Synthesis and antibacterial properties of new N4-acetylated hexahydro-2,7-dioxopyrido[2,3-f]quinoxaline-8-carboxylic acids.

Yusuf M Al-Hiari, Ashok K Shakya, Muhammed H Alzweiri, Tariq M Al-Qirim, Ghassan Shattat, Mustafa M El-Abadelah

Index: J. Enzyme Inhib. Med. Chem. 26(5) , 649-56, (2011)

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Abstract

Direct interaction between 7-chloro-1-cyclopropyl-6-fluoro-8-nitro-4-oxo-1,4-dihydroquinoline-3-carboxylic acid and primary α-amino acids (exemplified by glycine, alanine, and l-valine) in aqueous ethanolic NaHCO(3) at 70-80°C for 24-72 h produced the respective N-(4-oxoquinolin-7-yl)-α-amino acids (6a-c). The latter derivatives underwent reductive lactamization upon treatment with Na(2)S(2)O(4) 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.