Reaktion #1519115

Reaktionsgleichung

Crotyl bromide

dimethyl malate

diisopropylamine

BuLi

→

(2S,3R)-3-(2-butenyl)-2-hydroxysuccinic dimethyl ester

Lösungsmittel

THF

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   TemperaturThe mixture is warmed to −20° C. over 2 hours
2. 2
   Temperaturcooled to −78° C
3. 3
   Temperaturto warm to rt
4. 4
   workup.STIRRINGstirred overnight
5. 5
   TemperaturThe solution is then cooled to −10° C.
6. 6
   Sonstigequenched with NH4Cl (10%, 100 mL)
7. 7
   SonstigeThe THF is removed
8. 8
   Extraktionthe residue extracted with EtOAc (2×200 mL)
9. 9
   WaschenThe combined organic layers are washed with HCl (1 N, 3×50 mL), saturated aqueous NaHCO3 (3×50 mL), and brine
10. 10
    Trocknendried over Na2SO4
11. 11
    FiltrationThe solution is filtered
12. 12
    Einengenconcentrated
13. 13
    Sonstigeto give a residue, which
14. 14
    Sonstigeis purified on silica gel (EtOAc/hexane 1:4)

Vorschrift

To a solution of diisopropylamine (14 mL, 100 mmol) in THF at 0° C. is added BuLi (2.5 M in hexane, 40 mL, 100 mmol) over 10 minutes. The mixture is stirred at rt for 30 minutes, and then added via cannula to a −78° C. solution of dimethyl malate B-1 (7.71 g, 47.6 mmol) in THF (130 mL). The mixture is warmed to −20° C. over 2 hours, and then cooled to −78° C. Crotyl bromide (8.1 g, 60 mmol) is added, then the mixture is allowed to warm to rt and then stirred overnight. The solution is then cooled to −10° C. and quenched with NH4Cl (10%, 100 mL). The THF is removed and the residue extracted with EtOAc (2×200 mL). The combined organic layers are washed with HCl (1 N, 3×50 mL), saturated aqueous NaHCO3 (3×50 mL), and brine, then dried over Na2SO4. The solution is filtered and concentrated to give a residue, which is purified on silica gel (EtOAc/hexane 1:4) to afford (2S,3R)-3-(2-butenyl)-2-hydroxysuccinic dimethyl ester B-2.

Quelle