反应详情

A solution of 0.52 g of pyro-L-glutamic acid, 1.72 g of phenylalanine benzyl ester toluene sulfonic acid and 0.55 mg of N-ethylmorpholine in 5 ml of dimethylformamide (DMF) and 20 ml of dichloromethane was cooled in an ice bath with stirring. A solution of 0.826 g of dicyclohexylcarbodiimide in 2 ml dichloromethane was added to the above reaction mixture. The reaction mixture was stirred in an ice water bath for 1 hour and then at room temperature overnight. Dicyclohexylurea was removed by filtration and the product was washed in ethyl acetate. Solvents of the combined filtrates were removed under reduced pressure with a rotary evaporator at 40°. Ethyl acetate (25 ml) was added to the residue and the organic solution was washed unit neutral. The organic phase was dried over anhydrous MgSO4, filtered and then the solvent was removed with a rotary evaporator. The material was crystallized from isopropanol and ether, yield; 1.01 g of white needles, m.p. 103°-104.5° C. The material was shown to be homogeneous by paper electrophoresis and by TLC with five separate solvent systems. Elemental analysis yielded the following results:

1. stirringThe reaction mixture was stirred in an ice water bath for 1 hour
2. customat room temperature
3. customovernight
4. customDicyclohexylurea was removed by filtration
5. washthe product was washed in ethyl acetate
6. customSolvents of the combined filtrates were removed under reduced pressure with a rotary evaporator at 40°
7. additionEthyl acetate (25 ml) was added to the residue
8. washthe organic solution was washed unit neutral
9. dry with materialThe organic phase was dried over anhydrous MgSO4
10. filtrationfiltered
11. customthe solvent was removed with a rotary evaporator
12. customThe material was crystallized from isopropanol and ether, yield; 1.01 g of white needles, m.p. 103°-104.5° C
13. customseparate solvent systems
14. customElemental analysis yielded the
15. customfollowing results