反应详情

In 100 ml of tetrahydrofuran were dissolved 4.6 g of benzyloxycarbonyl-2-(2,5-dioxopyrrolidin-3-yl)glycine and 2.5 ml of benzyl alcohol, and under cooling at 0°-5° C. 2.4 ml of pyridine and 3.6 g of dicyclohexylcarbodiimide were added to the solution in that order. The mixture was stirred at the same temperature as above for 4 hours and then at room temperature for 18 hours. The precipitated dicyclohexylurea were filtered off and the filtrate was concentrated under reduced pressure. The residue was poured into a mixture of 300 ml of 2 N hydrochloric acid and 300 ml of ethyl acetate. 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 dissolved in a small amount of ethyl ether. To this solution was added petroleum ether to give crystals. Yield 4.8 g.

1. temperatureunder cooling at 0°-5° C
2. waitat room temperature for 18 hours
3. filtrationThe precipitated dicyclohexylurea were filtered off
4. concentrationthe filtrate was concentrated under reduced pressure
5. additionThe residue was poured into a mixture of 300 ml of 2 N hydrochloric acid and 300 ml of ethyl acetate
6. customThe ethyl acetate layer was separated
7. washwashed with 2 N hydrochloric acid
8. dry with materialdried over sodium sulfate
9. concentrationconcentrated under reduced pressure
10. customThe concentrate was chromatographed on a silica gel column
11. washeluted with toluene-ethyl acetate (3:1)
12. concentrationThe eluate was concentrated under reduced pressure
13. dissolutionthe residue was dissolved in a small amount of ethyl ether
14. additionTo this solution was added petroleum ether
15. customto give crystals