Toluene → Ethyl alpha-hydroxyimino(5,6-dihydro-1,4-oxathiin-2-yl)acetate

Participants

Reaction Steps

Ethyl 4-(2-hydroxy-ethylthio)-2-hydroxyimino-3-oxobutyrate (321 g.) is dissolved in boiling toluene (3.2 liters) and para-toluenesulphonic acid monohydrate (26 g.) is then added. Vigorous boiling occurs, with liberation of water, which is removed in a Dean-Stark apparatus. The heating of the reaction mixture is continued for 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 slowly solidifies.

Provenance & Evidence