Reacción #6524

Ecuación de reacción

sodium acetate

5-(pyrrol-2-yl)oxazole

dimethylformamide

phosphorus oxychloride

→

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

Rendimiento 80.0%

Disolventes

chloroform

1,2-dichloroethane

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.STIRRINGThe mixture was stirred 20 minutes
2. 2
   Temperaturawhile cooling in an ice bath
3. 3
   TemperaturaThe reaction mixture was then heated
4. 4
   Temperaturaunder reflux for 20 minutes
5. 5
   TemperaturaAfter heating
6. 6
   Temperaturaunder reflux for 20 minutes
7. 7
   Temperaturathe mixture was cooled to room temperature
8. 8
   Otrothe organic layer separated
9. 9
   Lavadowashed with aqueous sodium carbonate
10. 10
    Secadodried over anhydrous sodium sulfate
11. 11
    Otroevaporation of the solvent at reduced pressure
12. 12
    Otrothe crude product was purified by column chromatography with chloroform elution

Procedimiento

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).

Fuente