Hydrochloric Acid → 7-Benzenesulfonyl-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8naphthyridine-3-carboxylic acid

Participants

Reaction Steps

In 8.0 ml of dioxane was suspended 800 mg of ethyl 7-benzenesulfonyl-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine 3-carboxylate, and 4.9 ml of N hydrochloric acid was added thereto, after which the resulting mixture was subjected to reaction under reflux for 4 hours. The solvent was removed by distillation under reduced pressure, and the residue thus obtained was purified by a column chromatography [Wako Silica Gel C-200, eluant: benzene-ethyl acetate (10:1 by volume)] to obtain 560 mg (yield 74.3% of 7-benzenesulfonyl-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8naphthyridine-3-carboxylic acid having a melting point of 252°-258° C.

Provenance & Evidence