Tosufloxacin tosylate (CAS NO.: 115964-29-9), with other name of 1,8-Naphthyridine-3-carboxylic acid, 7-(3-amino-1-pyrrolidinyl)-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-, 4-methylbenzenesulfonate (1:1), could be produced through many synthetic methods.

Following is one of the synthesis routes: Ethyl 7-chloro-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate (I) reacts with 3-aminopyrrolidine dihydrochloride (II), and then the resulting mixture is treated with potassium hydroxide and p-toluenesulfonic acid monohydrate in order to produce (rac)-7-(3-amino-1-pyrrolidinyl)-6-fluoro-1-(2,4-difluorophenyl)- 1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid p-toluenesulfonate hydrate.