Reaktion #40742

Reaktionsgleichung

dimethyl carbonate

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

n-BuLi

hexane

→

5-chloro-3-ethyl-2-naphthalen-1-yl-3H-imidazole-4-carboxylic acid ethyl ester

Lösungsmittel

Water

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThe resulting solution is stirred at −78° C. for 30 min
2. 2
   Temperaturwarmed to rt slowly
3. 3
   workup.STIRRINGstirred for an additional 60 min at rt
4. 4
   Sonstigeto quench
5. 5
   Sonstigethe reaction, and THF
6. 6
   Sonstigeis evaporated under reduced pressure
7. 7
   ExtraktionThe residue is extracted with EtOAc (30 ml×2)
8. 8
   Waschenthe combined organic layers are washed with water and brine
9. 9
   Trocknendried over sodium sulfate
10. 10
    Einengenconcentrated
11. 11
    SonstigeThe crude product is purified through silica gel chromatography (hexanes/EtOAc, from 20:1 to 10:1)

Vorschrift

To a solution of 4,5-dichloro-1-ethyl-2-naphthalen-1-yl-1H-imidazole (2.87 g, 9.86 mmol) in anhydrous THF (60 ml) at −78° C. under nitrogen is added a solution of n-BuLi in hexane (1.6 M, 6.78 ml, 10.84 mmol, 1.1 eq.) dropwise. The resulting mixture is stirred at −78° C. for 1 hr, followed by the addition of dimethyl carbonate (2.66 g, 29.6 mmol, 3.0 eq.). The resulting solution is stirred at −78° C. for 30 min, warmed to rt slowly, and stirred for an additional 60 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) and the combined organic layers are washed with water and brine, dried over sodium sulfate, and concentrated. The crude product is purified through silica gel chromatography (hexanes/EtOAc, from 20:1 to 10:1) to give 5-chloro-3-ethyl-2-naphthalen-1-yl-3H-imidazole-4-carboxylic acid ethyl ester. LCMS 315 (M+1).

Quelle