Réaction #6524

Équation de réaction

sodium acetate

5-(pyrrol-2-yl)oxazole

dimethylformamide

phosphorus oxychloride

→

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

Rendement 80.0%

Solvants

chloroform

1,2-dichloroethane

Conditions de réaction

Traitement

1. 1
   workup.STIRRINGThe mixture was stirred 20 minutes
2. 2
   Températurewhile cooling in an ice bath
3. 3
   TempératureThe reaction mixture was then heated
4. 4
   Températureunder reflux for 20 minutes
5. 5
   TempératureAfter heating
6. 6
   Températureunder reflux for 20 minutes
7. 7
   Températurethe mixture was cooled to room temperature
8. 8
   Autrethe organic layer separated
9. 9
   Lavagewashed with aqueous sodium carbonate
10. 10
    Séchagedried over anhydrous sodium sulfate
11. 11
    Autreevaporation of the solvent at reduced pressure
12. 12
    Autrethe crude product was purified by column chromatography with chloroform elution

Mode opératoire

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).

Source