反应详情

A solution of ethyl 2-chloroacetyl-2-methoxyiminoacetate (65 g.) in dry chloroform (130 ml.) was added to a stirred mixture of 2-mercaptoethanol (25 g.), triethylamino (35 g.) and dry chloroform (70 ml.) at 20° C. over 30 minutes, and stirred at the same temperature for 2.5 hours. After the solution was adjusted to pH 1.0 with 10% hydrochloric acid under ice cooling, the chloroform layer was separated, washed with water twice and dried over magnesium sulfate. The solution was concentrated in vacuo at 40° C. to give yellow oil. The oil was dissolved in toluene (600 ml.), and then p-toluenesulfonic acid (5.5 g.) was added to the toluene solution. The solution was heated under reflux for 2 hours while removing the produced water. The resultant solution was allowed to cool at room temperature and filtered. The filtrate was washed with water (100 ml.) three times, a saturated aqueous solution of sodium bicarbonate (100 ml.) twice and water (100 ml.) twice in turn, and then dried over magnesium sulfate. The solution was concentrated under reduced pressure. The residue was subjected to column chromatography on silica gel "Kieselgel 60" [Trademark: manufactured by E. Merck] (1 kg.) and eluted with benzene. After the eluate was concentrated under reduced pressure, the residue was washed with diisopropyl ether and dried to give ethyl 2-(2,3-dihydro-1,4-oxathiin-6-yl)-2-methoxyiminoacetate (syn isomer, 21 g.), pale yellow crystals, mp. 64° to 66° C.

1. customthe chloroform layer was separated
2. washwashed with water twice
3. dry with materialdried over magnesium sulfate
4. concentrationThe solution was concentrated in vacuo at 40° C.
5. customto give yellow oil
6. temperatureThe solution was heated
7. temperatureunder reflux for 2 hours
8. customwhile removing the produced water
9. filtrationfiltered
10. washThe filtrate was washed with water (100 ml.) three times
11. dry with materiala saturated aqueous solution of sodium bicarbonate (100 ml.) twice and water (100 ml.) twice in turn, and then dried over magnesium sulfate
12. concentrationThe solution was concentrated under reduced pressure
13. washeluted with benzene
14. concentrationAfter the eluate was concentrated under reduced pressure
15. washthe residue was washed with diisopropyl ether
16. customdried