反应详情

Ethyl 7-(3,5-dimethyl-4-isoxazolyl)-4-hydroxy-6-(methyloxy)-3-quinolinecarboxylate (for a preparation see Intermediate 4) (28.4 g, 83 mmol) was suspended in a mixture of ethanol (200 ml) and NaOH (2M, 124 ml, 249 mmol) and the mixture was heated at reflux overnight, then evaporated to around 100 ml volume and the resulting solution washed with MTBE (100 ml). The aqueous layer was acidified to pH4 with 1M HCl, then the resulting solid collected by filtration and washed with water and dried overnight at 40° C. in the vacuum oven to give 7-(3,5-dimethyl-4-isoxazolyl)-4-hydroxy-6-(methyloxy)-3-quinolinecarboxylic acid (24.5 g, 78 mmol, 94% yield) as pale yellow solid. LCMS Rt 0.76 min, MH+ 315

1. temperaturethe mixture was heated
2. temperatureat reflux overnight
3. customevaporated to around 100 ml volume
4. washthe resulting solution washed with MTBE (100 ml)
5. filtrationthe resulting solid collected by filtration
6. washwashed with water
7. customdried overnight at 40° C. in the vacuum oven