Ethyl 7-chloro-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate → 7-Chloro-1-(2,4-difluorophenyl)-6-fluoro-4-oxo-1,4-dihydro-1,8-naphthyridine-3-carboxylic acid

Participants

Reaction Steps

In 10 ml of conc. hydrochloric acid was suspended 500 mg of ethyl 7-chloro-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylate, and the resulting suspension was subjected to reaction under reflux for 1 hour. The reaction mixture was diluted with 10 ml of water, and the crystals thus deposited were collected by filtration, and then washed with 2 ml of water to obtain 450 mg (yield 97.1%) of 7-chloro-1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid having a melting point of 238°-242° C.

Provenance & Evidence