Реакция #1174777

Уравнение реакции

ethyl acetate

HCl

Boc-L-leucinal

n-butyllithium

hexane

diisopropylamine

→

desired product

Выход 38.8%

4-t-Butyloxycarbonylamino-3-hydroxy-6-methylheptanoic acid ethyl ester

Выход 38.8%

Растворители

tetrahydrofuran

tetrahydrofuran

Условия реакции

Обработка

1. 1
   Другоеlowered to -78 degrees C
2. 2
   Температураwhile maintaining the temperature below -75 degrees C
3. 3
   workup.STIRRINGThe solution was stirred 10 min
4. 4
   workup.WAITAfter 30 min
5. 5
   Экстракцияand extracted with ether (3×200 mL)
6. 6
   ЭкстракцияThe combined ethereal extract
7. 7
   Промывкаwas washed with saturated sodium chloride
8. 8
   Сушкаdried with magnesium sulfate
9. 9
   Фильтрацияfiltered
10. 10
    ДругоеEvaporation of the filtrate in vacuo
11. 11
    Другоеgave 14 g of crude product which
12. 12
    Другоеwas purified by flash chromatography (20% ethyl acetate in hexane)

Методика

To diisopropylamine (7.7 g, 0.077 mol) in dry tetrahydrofuran (26 mL) cooled to -20 degrees C. under argon was added dropwise n-butyllithium in hexane (1.46M, 52.4 mL, 0.077 mol). The solution was stirred 15 min, the temperature lowered to -78 degrees C. and dry ethyl acetate (6.7 g, 0.077 mol) added dropwise while maintaining the temperature below -75 degrees C. The solution was stirred 10 min and a precooled (-78 degrees C.) tetrahydrofuran solution of Boc-L-leucinal (11 g, 0.051 mol) was added. After 30 min, 2M HCl (40 mL) was added and the mixture was slowly warmed to 10 degrees C. and extracted with ether (3×200 mL). The combined ethereal extract was washed with saturated sodium chloride and dried with magnesium sulfate and filtered. Evaporation of the filtrate in vacuo gave 14 g of crude product which was purified by flash chromatography (20% ethyl acetate in hexane) to give 6 g of desired product.

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