Reaktion #833211

Reaktionsgleichung

1-Methylcyclohexylcarbonyl chloride

L-aspartic acid β-benzyl ester

dichloromethane

→

benzyl 3-(1-methylcyclohexylcarbonylamino)-4-oxovalerate

Lösungsmittel

triethylamine

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturcooling
2. 2
   workup.STIRRINGThe resulting mixture was stirred with ice-
3. 3
   Temperaturcooling for an hour
4. 4
   Waschenwashed with 1N hydrochloric acid and water
5. 5
   Trocknendried over anhydrous magnesium sulfate
6. 6
   workup.DISTILLATIONThe solvent was then distilled off
7. 7
   workup.DISSOLUTIONthe oily residue (3.2 g) was dissolved in dimethoxyethane (30 ml)
8. 8
   workup.ADDITIONAcetic anhydride (4 ml), pyridine (4.8 ml) and 4-dimethylaminopyridine (0.12 g) were added
9. 9
   Temperaturthe mixture was refluxed for 1.5 hours
10. 10
    workup.ADDITIONAcetic acid (2 ml) was added
11. 11
    Temperaturthe whole mixture was refluxed for 2.5 hours
12. 12
    workup.DISTILLATIONThe solvent was distilled off
13. 13
    workup.ADDITIONwater was added
14. 14
    ExtraktionThe mixture was extracted with ethyl acetate
15. 15
    Waschenthe ethyl acetate layer was washed with diluted hydrochloric acid, water, aqueous sodium hydrogen carbonate and water in that order
16. 16
    Trocknendried over anhydrous magnesium sulfate
17. 17
    SonstigeThe residue (2.0 g) was purified by chromatography on silica gel (40 g) [eluent: hexane-acetone (9:1)]

Vorschrift

1-Methylcyclohexylcarbonyl chloride (1.6 g) was added dropwise to a mixture of L-aspartic acid β-benzyl ester (2.23 g), dichloromethane (30 ml) and triethylamine (30 ml) with ice-cooling and stirring. The resulting mixture was stirred with ice-cooling for an hour, washed with 1N hydrochloric acid and water and dried over anhydrous magnesium sulfate. The solvent was then distilled off and the oily residue (3.2 g) was dissolved in dimethoxyethane (30 ml). Acetic anhydride (4 ml), pyridine (4.8 ml) and 4-dimethylaminopyridine (0.12 g) were added and the mixture was refluxed for 1.5 hours. Acetic acid (2 ml) was added and the whole mixture was refluxed for 2.5 hours. The solvent was distilled off and water was added. The mixture was extracted with ethyl acetate and the ethyl acetate layer was washed with diluted hydrochloric acid, water, aqueous sodium hydrogen carbonate and water in that order, and dried over anhydrous magnesium sulfate. The residue (2.0 g) was purified by chromatography on silica gel (40 g) [eluent: hexane-acetone (9:1)] to give benzyl 3-(1-methylcyclohexylcarbonylamino)-4-oxovalerate as an oil; yield 1.2 g (34.8%).

Quelle