Reaktion #53240

Reaktionsgleichung

CBr4

butyllithium

N,N-dimethylamine ethanol

4-methoxypyridine

→

4-methoxy-2-bromopyridine

Ausbeute 22.0%

Lösungsmittel

water

—

hexanes

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITcontinued at 0° C. for one hour before the reaction mixture
2. 2
   TemperaturThe reaction temperature was maintained at 0° C. for 2.5 hours
3. 3
   Sonstigeto quench
4. 4
   Sonstigethe reaction
5. 5
   SonstigeThe aqueous layer was then separated
6. 6
   Extraktionextracted with methylene chloride
7. 7
   ExtraktionThe organic extractions
8. 8
   Waschenwere washed with brine
9. 9
   Trocknendried over magnesium sulfate
10. 10
    Sonstigeevaporated
11. 11
    Sonstigeto give crude product
12. 12
    SonstigeThe crude product was purified by column chromatography
13. 13
    SonstigeThe purified product was collected
14. 14
    Einengenconcentrated

Vorschrift

A solution of N,N-dimethylamine ethanol (78.086 g, 0.876 mole) in anhydrous hexanes(1241 mL.) was cooled to 0° C. and butyllithium (2M soln. 876 mL., 1.757 mole) was added by use of an addition funnel. After 30 minutes at 0° C., 4-methoxypyridine(47.87 g, 0.438 mole) was added. Stirring continued at 0° C. for one hour before the reaction mixture was cooled to −78° C. and a solution of CBr4 (363 g, 1.093 mole) was added. The reaction temperature was maintained at 0° C. for 2.5 hours. The water was then added to quench the reaction. The aqueous layer was then separated and extracted with methylene chloride. The organic extractions were washed with brine, dried over magnesium sulfate and evaporated to give crude product. The crude product was purified by column chromatography using 80/20 ethyl acetate/hexanes as the eluants. The purified product was collected and concentrated to give 4-methoxy-2-bromopyridine (17 g. 22% yield).

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