Реакция #463374

Уравнение реакции

ammonium chloride

lithium diisopropylamide

3,4-dichlorobenzyl bromide

methyl (R)-(-)-3-hydroxybutyrate

→

methyl (2R, 3R)-2-(3,4-dichlorobenzyl)-3-hydroxybutyrate

Выход 48.0%

Растворители

cyclohexane

hexamethylphosphoric triamide

tetrahydrofuran

water

ethyl ether

Условия реакции

Обработка

1. 1
   ТемператураThen, the temperature was raised to -25° C
2. 2
   workup.STIRRINGunder stirring
3. 3
   Температураwhile maintaining the temperature at -25° C
4. 4
   workup.ADDITIONAfter the dropwise addition
5. 5
   Температураthe temperature was raised to room temperature
6. 6
   workup.STIRRINGwith stirring
7. 7
   Температураunder cooling with ice
8. 8
   ТемператураThen, the temperature was raised to room temperature
9. 9
   Другоеfor liquid separation
10. 10
    ДругоеThe organic layer was collected by separation
11. 11
    workup.ADDITIONpost-treated by a conventional method
12. 12
    ДругоеThe product was purified by silica gel column chromatography (hexane/ethyl acetate=4/1)

Методика

9.45 g of methyl (R)-(-)-3-hydroxybutyrate was dissolved in 200 ml of tetrahydrofuran, and 112 ml of a 1.5M cyclohexane solution of lithium diisopropylamide was added thereto with stirring under cooling to -70° C. Then, the temperature was raised to -25° C. Then, 35 ml of a hexamethylphosphoric triamide solution of 21.1 g of 3,4-dichlorobenzyl bromide was dropwise added to this solution under stirring while maintaining the temperature at -25° C. After the dropwise addition, the temperature was raised to room temperature. Then, a saturated ammonium chloride aqueous solution was added to the reaction solution with stirring under cooling with ice. Then, the temperature was raised to room temperature, and ethyl ether and water were added thereto for liquid separation. The organic layer was collected by separation and post-treated by a conventional method. The product was purified by silica gel column chromatography (hexane/ethyl acetate=4/1) to obtain 10.6 g (yield: 48%) of methyl (2R, 3R)-2-(3,4-dichlorobenzyl)-3-hydroxybutyrate.

Источник