Реакция #72437

Уравнение реакции

4-Benzyloxycarbonylamino-2-(R)-hydroxybutyric acid

hydrochloric acid

Barium hydroxide octahydrate

Benzyl bromide

Barium oxide

→

title compound

Выход 36.0%

(R)-2-Benzyloxy-4-benzyloxycarbonylaminobutyric acid

Выход 36.0%

Растворители

N,N-dimethylformamide

chloroform

Water

Water

Условия реакции

Обработка

1. 1
   workup.STIRRINGthe mixture was vigorously stirred for 2 min
2. 2
   workup.STIRRINGthe mixture was vigorously stirred under ice cooling for 10 min
3. 3
   workup.STIRRINGthe mixture was vigorously stirred under ice cooling for 5 min
4. 4
   Другоеwas returned to room temperature
5. 5
   workup.STIRRINGwas vigorously stirred for 1.5 hr
6. 6
   Другоеthereto followed by separation
7. 7
   ЭкстракцияThe water layer was extracted with 22 mL+10 mL of chloroform
8. 8
   ПромывкаThe combined organic layers were washed with 30 mL of saturated brine
9. 9
   Сушкаwere dried over magnesium sulfate
10. 10
    Концентрированиеwere concentrated to dryness
11. 11
    Другоеto give 4.54 g of a crude product
12. 12
    ДругоеThe product was purified by column chromatography on 70 g of a neutral silica gel (chloroform→chloroform:ethyl acetate=4:1→chloroform:methanol=10:1→chloroform:methanol-acetic acid=10:1:0.1)

Методика

4-Benzyloxycarbonylamino-2-(R)-hydroxybutyric acid (2.245 g) synthesized according to the method of H. Naito et al. (J. Antibiot., Vol. 26, pp. 297-301 (1973)) was dissolved in 25.6 mL of N,N-dimethylformamide. Barium oxide (6.795 g) was added to the solution under ice cooling with stirring, and the mixture was vigorously stirred for 2 min. Barium hydroxide octahydrate (5.593 g) was added to the reaction mixture, and the mixture was vigorously stirred under ice cooling for 10 min. Benzyl bromide (3.16 mL) was added thereto, and the mixture was vigorously stirred under ice cooling for 5 min. The reaction mixture was returned to room temperature and was vigorously stirred for 1.5 hr. Water (0.48 mL) was added under ice cooling, and the mixture was diluted with 70 mL of chloroform. 4 M hydrochloric acid (31 mL) was added to the diluted solution. Water (11 mL) was then added thereto followed by separation. The water layer was extracted with 22 mL+10 mL of chloroform. The combined organic layers were washed with 30 mL of saturated brine, were dried over magnesium sulfate and were concentrated to dryness to give 4.54 g of a crude product. The product was purified by column chromatography on 70 g of a neutral silica gel (chloroform→chloroform:ethyl acetate=4:1→chloroform:methanol=10:1→chloroform:methanol-acetic acid=10:1:0.1) to give the title compound (1.107 g, 36%).

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