反应详情

Sodium ethoxide (2.8 g, 41 mmol) was added to a suspension of the 1-(2,4-bis-benzyloxy-5-tert-butyl-phenyl)-ethanone (7.8 g, 20 mmol) in ethanol (40 ml). Diethyl oxalate (4 ml, 29.5 mmol) was added and the resulting suspension heated under reflux for ˜2 hrs. to give a pale red solution. The solution was allowed to cool and poured into water (200 ml), the mixture was acidified with hydrochloric acid (50 ml, 1M) and extracted with dichloromethane (150 ml). The extracts were washed with water (2×200 ml) and saturated aqueous sodium chloride solution (100 ml). The solution was dried over anhydrous sodium sulphate and concentrated to a yellow gum. Trituration with hexane gave a yellow solid. Solids were removed by filtration and washed with hexane and dried in vacuo (40° C.), to give 4-(2,4-Bis-benzyloxy-5-tert-butyl-phenyl)-2-hydroxy-4-oxo-but-2-enoic acid ethyl ester as a yellow powder (9.1 g, 93%).

1. temperaturethe resulting suspension heated
2. temperatureunder reflux for ˜2 hrs
3. customto give a pale red solution
4. temperatureto cool
5. extractionextracted with dichloromethane (150 ml)
6. washThe extracts were washed with water (2×200 ml) and saturated aqueous sodium chloride solution (100 ml)
7. dry with materialThe solution was dried over anhydrous sodium sulphate
8. concentrationconcentrated to a yellow gum
9. customTrituration with hexane gave a yellow solid
10. customSolids were removed by filtration
11. washwashed with hexane
12. customdried in vacuo (40° C.)