反应详情

温度

10 °C

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 (1.46 M, 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, 2 M 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.

1. customlowered to -78 degrees C
2. temperaturewhile maintaining the temperature below -75 degrees C
3. stirringThe solution was stirred 10 min
4. waitAfter 30 min
5. extractionand extracted with ether (3 ×200 mL)
6. extractionThe combined ethereal extract
7. washwas washed with saturated sodium chloride
8. dry with materialdried with magnesium sulfate
9. filtrationfiltered
10. customEvaporation of the filtrate in vacuo
11. customgave 14 g of crude product which
12. customwas purified by flash chromatography (20% ethyl acetate in hexane)