Reaktion #6524

Reaktionsgleichung

sodium acetate

5-(pyrrol-2-yl)oxazole

dimethylformamide

phosphorus oxychloride

→

5-(5-formylpyrrol-2-yl)oxazole

Ausbeute 80.0%

Lösungsmittel

chloroform

1,2-dichloroethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGThe mixture was stirred 20 minutes
2. 2
   Temperaturwhile cooling in an ice bath
3. 3
   TemperaturThe reaction mixture was then heated
4. 4
   Temperaturunder reflux for 20 minutes
5. 5
   TemperaturAfter heating
6. 6
   Temperaturunder reflux for 20 minutes
7. 7
   Temperaturthe mixture was cooled to room temperature
8. 8
   Sonstigethe organic layer separated
9. 9
   Waschenwashed with aqueous sodium carbonate
10. 10
    Trocknendried over anhydrous sodium sulfate
11. 11
    Sonstigeevaporation of the solvent at reduced pressure
12. 12
    Sonstigethe crude product was purified by column chromatography with chloroform elution

Vorschrift

To an ice cooled 1 mL dimethylformamide was added 0.82 g (5.4 mmol) of phosphorus oxychloride while stirring under a nitrogen atmosphere. The mixture was stirred 20 minutes and then was added a solution of 0.60 g (4.5 mmol) of 5-(pyrrol-2-yl)oxazole in 15 mL of 1,2-dichloroethane while cooling in an ice bath. The reaction mixture was then heated under reflux for 20 minutes. After cooling to room temperature, 50 mL of chloroform was added followed by 60 mL of saturated aqueous sodium acetate. After heating under reflux for 20 minutes, the mixture was cooled to room temperature and the organic layer separated, washed with aqueous sodium carbonate and dried over anhydrous sodium sulfate. Following evaporation of the solvent at reduced pressure, the crude product was purified by column chromatography with chloroform elution to give 0.58 g (80%) of 5-(5-formylpyrrol-2-yl)oxazole as a white solid, m.p. 152°-153° C.; 1H-NMR (Acetone-d6) δ 6.68 (d, 1H, ArH), 7.09 (d, 1H, ArH), 7.61 (S, 1H, ArH), 8,22 (s, 1H, ArH), 9.57 (s, 1H, CHO).

Quelle