反应详情

To a solution of 37% formalin (12 ml) and formic acid (18 ml) was added 6.0 g of 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-1,8-naphthyridine-3-carboxylic acid, and the mixture was heated at 120°-125° C. for 4 hours with stirring. The mixture was then concentrated to dryness under reduced pressure. The residue was adjusted to pH 8 by addition of aqueous 7% sodium bicarbonate, and extracted with chloroform. The extract was dried and the solvent was evaported. The crystalline residue was recrystallized from a mixture of dichloromethane and ethanol to give 5.0 g of 1-ethyl-6-fluoro-1,4-dihydro-7-(4-methyl-1-piperazinyl)-4-oxo-1,8-naphthyridine-3-carboxylic acid, m.p. 228°-230° C.

1. temperaturethe mixture was heated at 120°-125° C. for 4 hours
2. concentrationThe mixture was then concentrated to dryness under reduced pressure
3. additionThe residue was adjusted to pH 8 by addition of aqueous 7% sodium bicarbonate
4. extractionextracted with chloroform
5. customThe extract was dried
6. customThe crystalline residue was recrystallized from a mixture of dichloromethane and ethanol