Dicyclohexylcarbodiimide → (3S,6R)-1-benzyl-3,6-dimethylpiperazine-2,5-dione

Temperature

0 °C

A 0.98 g portion of N-tert-butoxycarbonyl-L-alanine was added to 50 ml of 0° C.-cooled dichloromethane solution containing 1.07 g of DCC, and the mixture was stirred for 5 minutes. This solution was mixed with 10 ml of dichloromethane solution containing 1.0 g of N-benzyl-D-alanine methyl ester and stirred at room temperature for 2 days. White precipitate was separated by filtration and washed with diethyl ether and then the filtrate was concentrated. The residue was dried under reduced pressure, dissolved with 30 ml of dichloromethane, cooled to 0° C., mixed with 5 ml of trifluoroacetic acid and then stirred at room temperature for 3 hours. The reaction solution was neutralized with saturated aqueous sodium bicarbonate, extracted with chloroform, dried over anhydrous magnesium sulfate, filtered and then concentrated. The residue was subjected to a silica gel column chromatography and purified with n-hexane-ethyl acetate (1:5, v/v) to obtain 1.0 g of the title compound as a colorless oily substance.

1. stirringstirred at room temperature for 2 days
2. customWhite precipitate was separated by filtration
3. washwashed with diethyl ether
4. concentrationthe filtrate was concentrated
5. customThe residue was dried under reduced pressure
6. dissolutiondissolved with 30 ml of dichloromethane
7. additionmixed with 5 ml of trifluoroacetic acid
8. stirringstirred at room temperature for 3 hours
9. extractionextracted with chloroform
10. dry with materialdried over anhydrous magnesium sulfate
11. filtrationfiltered
12. concentrationconcentrated
13. custompurified with n-hexane-ethyl acetate (1:5

ORD record

ord-ef2eac2385b343328783cb4b7aa4a32a

Source dataset

uspto-grants-2004_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06673799B1