反应详情

Hydroxylamine hydrochloride (3.6 g, 52 mmol) was added to a solution of 4-(2,4-Bis-benzyloxy-5-tert-butyl-phenyl)-2-hydroxy-4-oxo-but-2-enoic acid ethyl ester (9.0 g, 18.5 mmol) in ethanol (75 ml) and the suspension heated under reflux for ˜4 hrs. The resulting solution was allowed to cool and poured into water (200 ml) to give an off-white precipitate. The solids were removed by filtration and taken up in dichloromethane (150 ml). The solution was washed with water (150 ml) and saturated aqueous sodium chloride solution (50 ml). The solution was dried over anhydrous sodium sulphate and concentrated to an off-white solid. Solids were washed with hexane and dried in vacuo (40° C.), to give 5-(2,4-bis-benzyloxy-5-tert-butyl-phenyl)-isoxazole-3-carboxylic acid ethyl ester as a pale brown powder (8.0 g, 89%).

1. temperaturethe suspension heated
2. temperatureunder reflux for ˜4 hrs
3. temperatureto cool
4. customto give an off-white precipitate
5. customThe solids were removed by filtration
6. washThe solution was washed with water (150 ml) and saturated aqueous sodium chloride solution (50 ml)
7. dry with materialThe solution was dried over anhydrous sodium sulphate
8. concentrationconcentrated to an off-white solid
9. washSolids were washed with hexane
10. customdried in vacuo (40° C.)