Synthesis of antimicrobial agents. VI. Studies on the synthesis of furo(3,2-b)(1,8)naphthyridine derivatives.

Abstract

As a part of a search for new antibacterial agents, 5-ethyl-8-oxo-5,8-dihydrofuro[3,2-b]-[1,8]naphthyridine-7-carboxylic acid and its 2,3-dihydrofuro derivative, the 4-aza analog of droxacin, were synthesized and their antibacterial activities were tested. Both compounds exhibited high antibacterial activities and a broad antibacterial spectrum [Escherichia coli, Proteus vulgaris, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Pseudomonas aeruginosa and Staphylococcus aureus]. In an attempt to find a suitable method for industrial-scale synthesis of these compounds, several methods for the furan ring cyclization of 6,7-disubstituted 1,8-naphthyridine-3-carboxylate derivatives were compared.