反应详情

In 50 ml of tetrahydrofuran was dissolved 6.2 g of benzyloxycarbonyl-2-(2,5-dioxopyrrolidin-3-yl)glycine and, following addition of 1.2 ml of pyridine, a solution of 5.4 g of 2,2,2-trichloroethyl chloroformate in 30 ml of tetrahydrofuran was added dropwise under cooling at 0°-5° C. The reaction mixture was stirred at the same temperature as above for 30 minutes and under reflux for 5 minutes and then concentrated to dryness under reduced pressure. The residue was extracted with ethyl acetate and the extract was washed with water, 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. After addition of petroleum ether to the solution, the mixture was allowed to stand in a refrigerator overnight to give crystals. Yield 1.1 g.

1. temperatureunder cooling at 0°-5° C
2. temperatureunder reflux for 5 minutes
3. concentrationconcentrated to dryness under reduced pressure
4. extractionThe residue was extracted with ethyl acetate
5. washthe extract was washed with water
6. dry with materialdried over sodium sulfate
7. concentrationconcentrated under reduced pressure
8. customThe concentrate was chromatographed on a silica gel column
9. washeluted with toluene-ethyl acetate (3:1)
10. concentrationThe eluate was concentrated under reduced pressure
11. dissolutionthe residue was dissolved in a small amount of ethyl ether
12. additionAfter addition of petroleum ether to the solution
13. customto stand in a refrigerator overnight
14. customto give crystals