Reaktion #216969

Reaktionsgleichung

1,1-dimethylethanol

4-bromo-2-methyl-2-butene

diisopropylamine

n-butyllithium

HMPA

→

title compound

Ausbeute 82.0%

5-Methyl-4-hexenoic acid, 1,1-dimethylethyl ester

Ausbeute 82.0%

Lösungsmittel

THF

hexane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe temperature below 0° C
2. 2
   workup.WAITAfter an additional 10 min
3. 3
   Sonstigethe temperature below -60° C
4. 4
   workup.STIRRINGThe resulting colorless solution was stirred for 30 min
5. 5
   workup.STIRRINGThe reaction was stirred at -75° C. for 6 h
6. 6
   Temperaturwarmed to room temperature
7. 7
   workup.WAITAfter 16 h
8. 8
   Sonstigethe reaction was quenched with saturated ammonium chloride solution
9. 9
   Extraktionextracted twice with ether
10. 10
    Trocknendried (MgSO4)
11. 11
    Sonstigeevaporated
12. 12
    SonstigePurification
13. 13
    workup.DISTILLATIONby distillation (b.p. 64°-67° C. @ 6 mmHg)

Vorschrift

To a stirred solution of 20.0 mL (142 mmol) of diisopropylamine in 160 mL of THF under argon at -10° C. was added a solution of 56 mL (140 mmol) of 2.5M n-butyllithium in hexane at a rate to keep the temperature below 0° C. The resulting light yellow solution was stirred 15 min and to this reaction mixture was added 20 mL (115 mmol) of HMPA. After an additional 10 min, the reaction was cooled to -75° C. and 18.8 mL (140 mmol) of 1,1-dimethylethanol, acetate ester was added at a rate to keep the temperature below -60° C. The resulting colorless solution was stirred for 30 min and 20 g (134 mmol) of 4-bromo-2-methyl-2-butene was added over 10 min. The reaction was stirred at -75° C. for 6 h and then warmed to room temperature. After 16 h, the reaction was quenched with saturated ammonium chloride solution, extracted twice with ether, dried (MgSO4) and evaporated. Purification by distillation (b.p. 64°-67° C. @ 6 mmHg) gave title compound as a colorless oil, 20.1 g, 82% yield.

Quelle