(RS)-7,8-difluoro-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylic acid 、
(RS)-2-(4-amino-3-methoxyphenyl)piperazine 以(RS)-8-[3-(4-amino-3-methoxyphenyl)-1-piperazinyl]-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]-naphthyridine-3-carboxylic acid (1.40 g) is obtained in the form of a yellow solid的产率得到(RS)-8-[3-(4-amino-3-methoxyphenyl)-1-piperazinyl]-1-methyl-4-oxo-1,4-dihydrobenzo[b][1,8]-naphthyridine-3-carboxylic acid