Hydrochloric Acid → Ethyl 1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-7-hydroxy-4-oxo-1,8-naphthyridine-3-carboxylate

Participants

Reaction Steps

In 2 ml of benzene was suspended 200 mg of ethyl 2-[2-(2,4-difluorophenylamino)-5-fluoro-6-hydroxynicotinoyl]acetate, and 87 mg of N,N-dimethylformamide dimethylacetal was added thereto, after which the resulting mixture was subjected to reaction under reflux for 10 hours. Thereafter the crystals thus deposited were collected by filtration. To the crystals thus obtained were added 0.5 ml of methanol and 1 ml of water, and the pH thereof was adjusted to 1.0 with 2N hydrochloric acid, after which the crystals thus deposited were collected by filtration to obtain 80 mg (yield 38.9%) of ethyl 1-(2,4-difluorophenyl)-6-fluoro-1,4-dihydro-7-hydroxy-4-oxo-1,8-naphthyridine-3-carboxylate having a melting point of 243°-248° C.

Provenance & Evidence