Reaktion #40737

Reaktionsgleichung

4,5-dibromo-1-ethyl-2-naphthalen-1-yl-1H-imidazole

n-BuLi

hexane

n-BuLi

hexane

chlorotrimethylsilane

diethyl carbonate

tetrabutylammonium fluoride

→

1-ethyl-2-naphthalen-1-yl-1H-imidazole-4-carboxylic acid ethyl ester

Lösungsmittel

THF

THF

Water

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThe resulting solution is stirred at −78° C
2. 2
   workup.WAITAfter 1 hour
3. 3
   workup.STIRRINGThe resulting mixture is stirred at −78° C. for 1 hr
4. 4
   workup.STIRRINGThe resulting solution is stirred at −78° C. for 30 min
5. 5
   Sonstigewaned to rt
6. 6
   workup.STIRRINGstirred for an additional 30 min at rt
7. 7
   Sonstigeto quench
8. 8
   Sonstigethe reaction, and THF
9. 9
   Sonstigeis evaporated under reduced pressure
10. 10
    ExtraktionThe residue is extracted with EtOAc (30 ml×2)
11. 11
    WaschenThe combined organic layers are washed with water and brine
12. 12
    Trocknendried over sodium sulfate
13. 13
    Einengenconcentrated
14. 14
    Sonstigeto give the crude product, which
15. 15
    workup.STIRRINGthe resulting mixture is stirred at it for 2 hr
16. 16
    SonstigeThe solvent is evaporated under reduced pressure
17. 17
    workup.ADDITIONthe residue is diluted with water (30 ml)
18. 18
    ExtraktionThe mixture is extracted with EtOAc (30 ml×3)
19. 19
    Waschenwashed with water and brine
20. 20
    Trocknendried over Na2SO4
21. 21
    Einengenconcentrated
22. 22
    SonstigePurification through silica gel chromatography (hexanes/EtOAc, from 8:1 to 4:1)

Vorschrift

To a solution of 4,5-dibromo-1-ethyl-2-naphthalen-1-yl-1H-imidazole (3.80 g, 10 mmol) in anhydrous THF (60 ml) at −78° C. under nitrogen is added a solution of n-BuLi in hexane (1.6 M, 6.88 ml, 11 mmol, 1.1 eq.) dropwise. The resulting mixture is stirred at −78° C. for 1 hr, after which chlorotrimethylsilane (1.188 g, 11 mmol, 1.1 eq.) is added. The resulting solution is stirred at −78° C. After 1 hour, n-BuLi in hexane (1.6 M, 6.88 ml, 11 mmol, 1.1 eq.) is added dropwise. The resulting mixture is stirred at −78° C. for 1 hr, followed by the addition of diethyl carbonate (3.54 g, 30 mol, 3.0 eq.). The resulting solution is stirred at −78° C. for 30 min, waned to rt slowly, and stirred for an additional 30 min at rt. Water (30 ml) is added to quench the reaction, and THF is evaporated under reduced pressure. The residue is extracted with EtOAc (30 ml×2). The combined organic layers are washed with water and brine, dried over sodium sulfate, and concentrated to give the crude product, which is dissolved in THF (30 ml). To this THF solution is added tetrabutylammonium fluoride (1.1 eq.), and the resulting mixture is stirred at it for 2 hr. The solvent is evaporated under reduced pressure, and the residue is diluted with water (30 ml). The mixture is extracted with EtOAc (30 ml×3), washed with water and brine, dried over Na2SO4 and concentrated. Purification through silica gel chromatography (hexanes/EtOAc, from 8:1 to 4:1) affords 1-ethyl-2-naphthalen-1-yl-1H-imidazole-4-carboxylic acid ethyl ester. LCMS 295 (M+1).

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