1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1H-pyrazol-4-yl)-1,8-naphthyridine-3-carboxylic acid, ethyl ester 、 alkaline earth salt of/the/ methylsulfuric acid 反应 2.0h,
以70%的产率得到1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1H-pyrazol-4-yl)-1,8-naphthyridine-3-carboxylic acid