Reaktion #167170

Reaktionsgleichung

water

MeI

2-tert-Butoxycarbonylamino-3-hydroxy-3-methyl-butyric acid

NaH

→

2-tert-Butoxycarbonylamino-3-methoxy-3-methyl-butyric acid

Ausbeute 94.0%

Lösungsmittel

ethyl acetate

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONUpon completion of the addition
2. 2
   Sonstigethe solution was removed from the ice bath
3. 3
   Temperaturto warm to room temperature
4. 4
   Sonstigethe crude reaction mixture
5. 5
   workup.STIRRINGwith stirring
6. 6
   EinengenThe quenched mixture was concentrated in vacuo
7. 7
   Sonstigepartitioned between diethyl ether and water
8. 8
   ExtraktionThe ether layer was extracted with sodium bicarbonate twice
9. 9
   Extraktionextracted three times with ethyl acetate
10. 10
    WaschenThe combined ethyl acetate layers were washed with water, sodium thiosulfate, water
11. 11
    Trocknendried with sodium sulfate
12. 12
    Einengenconcentrated

Vorschrift

2-tert-Butoxycarbonylamino-3-hydroxy-3-methyl-butyric acid (1.0 g, 4.29 mmol) was dissolved in THF (14 mL) and cooled to 0° C. in an external ice/brine bath. MeI (2.13 mL, 34.3 mmol) was added at 0° C. Solid NaH (60% dispersion in mineral oil, 0.514 g, 12.87 mmol) was added slowly at 0° C. Upon completion of the addition, the solution was removed from the ice bath and allowed to warm to room temperature, and stirred. After 18 hours, the crude reaction mixture was diluted in ethyl acetate and water was added slowly with stirring. The quenched mixture was concentrated in vacuo and partitioned between diethyl ether and water. The ether layer was extracted with sodium bicarbonate twice. The combined bicarbonate layers were acidified with aqueous citric acid to pH 3 and extracted three times with ethyl acetate. The combined ethyl acetate layers were washed with water, sodium thiosulfate, water, dried with sodium sulfate and concentrated to yield 2-tert-Butoxycarbonylamino-3-methoxy-3-methyl-butyric acid (0.99 g, 94%) as an oil.

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