L-Serine → methyl (2S)-3-hydroxy-2-[(4-nitrobenzyloxycarbonyl)amino]propionate

To a stirred solution of L-serine (3.5 g) and sodium hydrogen carbonate (7.5 g) in water (46 ml) was added 4-nitrobenzyloxycarbonyl chloride (6.4 g) in diethyl ether (10 ml) at ambient temperature. After stirring for 2 hours, to the solution were added 4-nitrobenzyloxycarbonyl chloride (6.4 g) in diethyl ether (10 ml), and sodium hydrogen carbonate (3.6 g). After stirring for 3 hours, the aqueous layer was separated and washed with ethyl acetate After adjusting the pH to 2 with concentrated hydrochloric acid, the aqueous solution was extracted twice with ethyl acetate, dried over magnesium sulfate and evaporated. To the residue were added methanol (40 ml) and concentrated sulfuric acid (0.7 ml), and the solution was stirred at 50°-55° C. for 2.5 hours. To the mixture was added triethylamine (4.2 ml) and the mixture was evaporated in vacuo. The resulting residue was poured into a mixture of ethyl acetate and water. The organic layer was separated, washed twice with brine, dried over magnesium sulfate and evaporated. The residue was chromatographed on silica gel (300 ml) and eluted with a mixture of acetone and dichloromethane (8:92, V/V) to give methyl (2S)-3-hydroxy-2-[(4-nitrobenzyloxycarbonyl)amino]propionate (2.14 g).

1. stirringAfter stirring for 3 hours
2. customthe aqueous layer was separated
3. washwashed with ethyl acetate
4. extractionthe aqueous solution was extracted twice with ethyl acetate
5. dry with materialdried over magnesium sulfate
6. customevaporated
7. additionTo the residue were added methanol (40 ml) and concentrated sulfuric acid (0.7 ml)
8. stirringthe solution was stirred at 50°-55° C. for 2.5 hours
9. additionTo the mixture was added triethylamine (4.2 ml)
10. customthe mixture was evaporated in vacuo
11. additionThe resulting residue was poured into a mixture of ethyl acetate and water
12. customThe organic layer was separated
13. washwashed twice with brine
14. dry with materialdried over magnesium sulfate
15. customevaporated
16. customThe residue was chromatographed on silica gel (300 ml)
17. washeluted with a mixture of acetone and dichloromethane (8:92, V/V)

ORD-Eintrag

ord-1591657b67844ea28875d1752331ea6d

Quelldatensatz

uspto-grants-1990_05

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US04921852