Reaction #84035

Reaction equation

Methyl chloroformate

L-Valine

NaOH

sodium carbonate

→

(S)-2-(methoxycarbonylamino)-3-methylbutanoic acid

Conditions

Workup

1. 1
   Otherreach room temperature
2. 2
   OtherThe reaction mixture was separated with ether (3×200 mL)
3. 3
   Otherthe aqueous layer was contained in a round bottom flask
4. 4
   Temperaturecooled in a ice-water bath
5. 5
   workup.ADDITIONConcentrated HCl (aq) was added drop wise until pH 2
6. 6
   Otherwas brought to room temperature
7. 7
   Extractionextracted with dichloromethane (3×200 mL)
8. 8
   Dryingdried (sodium sulfate)
9. 9
   Otherthe solids were removed by filtration
10. 10
    OtherThe solvents of the filtrate were removed under reduced pressure
11. 11
    Otherto afford a white solid
12. 12
    OtherThe white solid was further dried in vacuum (25.3 g, 86%)

Procedure

To L-Valine (20 g, 167.3 mmol) in a stirred aqueous NaOH (1M, 167 mL) solution in a round bottom flask (1 L), sodium carbonate (8.866 g, 83.6 mmol) was added. The flask was cooled to 0° C. in an ice-water bath. Methyl chloroformate (17.4 g, 184 mmol) was added drop wise and the reaction mixture was allowed to stir for 15 hours and reach room temperature. The reaction mixture was separated with ether (3×200 mL), and the aqueous layer was contained in a round bottom flask and cooled in a ice-water bath. Concentrated HCl (aq) was added drop wise until pH 2. The mixture was brought to room temperature and extracted with dichloromethane (3×200 mL). The organic layers were pooled, dried (sodium sulfate), and the solids were removed by filtration. The solvents of the filtrate were removed under reduced pressure to afford a white solid. The white solid was further dried in vacuum (25.3 g, 86%).

Source