PURPOSE: To obtain a novel compound useful as an intermediate for synthesizing a novel pyridobenzoxadiazine derivative as a low toxicity antibacterial agent having a strong and wide antibacterial activity.
CONSTITUTION: A compound represented by formula I, (wherein R1 is an imidazole or a 4-methyl-1-piperazine ring; and R2 is a lower alkyl), such as 6-fluoro-8-hydroxy-7-(1-imidazolyl)-1-(methyl amino)-4-oxo-1,4-dihydro-3-quinoline carboxylic acid. This compound is obtained, for example, by reducing 2,3- difluoro-6-nitrophenol, reacting the produced amine with diethyldiethoxymethylenemalonato, protecting the hydroxy group of the produced compound represented by formula II, (wherein X' is H), successively conducting cyclization and amination for obtaining a compound represented by formula III, (wherein R' is benzyl, methyl, or the like), protecting the amino group of the compound followed by alkylation, to thereby provide a compound represented by formula IV, (wherein R" is formyl, acetyl, or the like), and finally aminating and deblocking the same.
NIIMA NOBUO
KAMATA MIYAKO
AOKI MASAHIRO
OTSUKA TATSUO
