Реакция #6524

Уравнение реакции

sodium acetate

5-(pyrrol-2-yl)oxazole

dimethylformamide

phosphorus oxychloride

→

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

Выход 80.0%

Растворители

chloroform

1,2-dichloroethane

Условия реакции

Обработка

1. 1
   workup.STIRRINGThe mixture was stirred 20 minutes
2. 2
   Температураwhile cooling in an ice bath
3. 3
   ТемператураThe reaction mixture was then heated
4. 4
   Температураunder reflux for 20 minutes
5. 5
   ТемператураAfter heating
6. 6
   Температураunder reflux for 20 minutes
7. 7
   Температураthe mixture was cooled to room temperature
8. 8
   Другоеthe organic layer separated
9. 9
   Промывкаwashed with aqueous sodium carbonate
10. 10
    Сушкаdried over anhydrous sodium sulfate
11. 11
    Другоеevaporation of the solvent at reduced pressure
12. 12
    Другоеthe crude product was purified by column chromatography with chloroform elution

Методика

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).

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