反应详情

In 30 ml of tetrahydrofuran were dissolved 1.53 g of benzyloxycarbonyl-2-(2,5-dioxopyrrolidin-3-yl)glycine and 1 ml of 2,2,2-trichloroethanol and under cooling at 0°-5° C., 0.8 ml of pyridine was added. Then, 1.2 g of dicyclohexylcarbodiimide was added and the mixture was stirred at the same temperature as above for 2 hours and at room temperature for 18 hours. The precipitated dicyclohexylurea separating out was filtered off and the filtrate was concentrated under reduced pressure. The residue was added to a mixture of 2 N hydrochloric acid and ethyl acetates and the ethyl acetate layer was separated, washed with 2 N hydrochloric acid, dried over sodium sulfate and concentrated under reduced pressure. The concentrate was chromatographed on a silica gel column and eluted with toluene-ethyl acetate (3:1). The eluate was concentrated under reduced pressure and the residue was crystallized from ethyl ether-petroleum ether. Yield 0.7 g.

1. temperatureunder cooling at 0°-5° C.
2. filtrationThe precipitated dicyclohexylurea separating out was filtered off
3. concentrationthe filtrate was concentrated under reduced pressure
4. additionThe residue was added to a mixture of 2 N hydrochloric acid and ethyl acetates
5. customthe ethyl acetate layer was separated
6. washwashed with 2 N hydrochloric acid
7. dry with materialdried over sodium sulfate
8. concentrationconcentrated under reduced pressure
9. customThe concentrate was chromatographed on a silica gel column
10. washeluted with toluene-ethyl acetate (3:1)
11. concentrationThe eluate was concentrated under reduced pressure
12. customthe residue was crystallized from ethyl ether-petroleum ether