反应详情

N-Benzylglycine methyl ester hydrochloride (23.0 g) is dissolved in ethanol (180 ml) and thereto is added triethylamine (11.1 g) under ice-cooling and further added dropwise diketene (9.2 g). The mixture is stirred at room temperature for 1 hour and distilled to remove the solvent. The residue is dissolved in chloroform, washed with water, 10% hydrochloric acid, and water in this order, dried and then distilled to remove the solvent. The residue is dissolved in xylene (360 ml) and the solution is added dropwise to a solution of sodium methoxide [which is prepared from metal sodium (2.6 g) and methanol (180 ml)], and the mixture is stirred at 80° C. for 2.5 hours while distilling off methanol. After cooling, the reaction mixture is extracted with water. The extract is acidified with 10% hydrochloric acid and extracted with ethyl acetate. The ethyl acetate extract is washed with water, dried and distilled to remove the solvent. The residue is recrystallized from n-hexane-isopropyl ether-diethyl ether to give 1-benzyl-3-acetyl-2,4-dioxopyrrolidine (20.33 g, 87.7%). m.p. 74°-75° C.

1. temperaturecooling
2. distillationdistilled
3. customto remove the solvent
4. dissolutionThe residue is dissolved in chloroform
5. washwashed with water, 10% hydrochloric acid, and water in this order
6. customdried
7. distillationdistilled
8. customto remove the solvent
9. dissolutionThe residue is dissolved in xylene (360 ml)
10. additionthe solution is added dropwise to a solution of sodium methoxide [which is prepared from metal sodium (2.6 g) and methanol (180 ml)]
11. stirringthe mixture is stirred at 80° C. for 2.5 hours
12. distillationwhile distilling off methanol
13. temperatureAfter cooling
14. extractionthe reaction mixture is extracted with water
15. extractionextracted with ethyl acetate
16. extractionThe ethyl acetate extract
17. washis washed with water
18. customdried
19. distillationdistilled
20. customto remove the solvent
21. customThe residue is recrystallized from n-hexane-isopropyl ether-diethyl ether