反应详情

In 4 ml of toluene was suspended 200 mg of ethyl 2-[2-(2,4-difluorophenylamino)-5-fluoro-6-hydroxynicotinoyl]acetate, and 200 mg of N,N-dimethylformamide dineopentylacetal was added thereto, after which the resulting mixture was subjected to reaction at room temperature for 4 hours. The crystals thus deposited were collected by filtration, and to the crystals were added 5 ml of ethanol and 5 ml of water, after which the pH thereof was adjusted to 1.0 with 2N hydrochloric acid. Thereafter, the crystals thus deposited were collected by filtration to obtain 155 mg (yield 75.4%) 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 244°-248° C. The physical properties of this compound were identical with those of the compound obtained in Example 40.

1. additionwas added
2. customafter which the resulting mixture was subjected to reaction at room temperature for 4 hours
3. filtrationThe crystals thus deposited were collected by filtration
4. additionto the crystals were added 5 ml of ethanol and 5 ml of water
5. filtrationThereafter, the crystals thus deposited were collected by filtration