反应详情

Ethyl 4-(2-hydroxy-ethylthio)-2-hydroxyimino-3-oxo-butyrate (321 g.) is dissolved in boiling toluene (3.2 liters) and paratoluenesulphonic acid monohydrate (26 g.) is then added. Vigorous boiling results, with liberation of water, which is removed in a DEAN and STARK apparatus. The reaction mixture is heated under reflux for a further 15 minutes. After cooling, the toluene solution is filtered, and washed three times with water (a total of 1.5 liters), then with a saturated sodium bicarbonate solution (200 cc.) and finally with water (500 cc.). It is dried over magnesium sulphate, treated with decolourising charcoal, filtered and concentrated to dryness under reduced pressure (20 mm.Hg). Ethyl α-hydroxyimino-(5,6-dihydro-1,4-oxathiin-2-yl)-acetate (273 g.) is obtained in the form of an oil which gradually solidifies.

1. additionis then added
2. customis removed in a DEAN and STARK apparatus
3. temperatureThe reaction mixture is heated
4. temperatureunder reflux for a further 15 minutes
5. temperatureAfter cooling
6. filtrationthe toluene solution is filtered
7. washwashed three times with water (a total of 1.5 liters), then with a saturated sodium bicarbonate solution (200 cc.)
8. dry with materialIt is dried over magnesium sulphate
9. additiontreated with decolourising charcoal
10. filtrationfiltered
11. concentrationconcentrated to dryness under reduced pressure (20 mm.Hg)