反应详情

To 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid ethyl ester (900 mg) was added 10 mL of a solution of boron tribromide (1 M) in DCM. The mixture was stirred at RT for 16 hours (h), then heated under reflux for 5 h. To complete the reaction neat boron tribromide (1.5 mL) was added dropwise and refluxing was continued for 3 h. After cooling to RT the mixture was poured onto crushed ice and extracted with DCM. The combined organic phases were filtered through a plug of diatomaceous earth and concentrated under reduced pressure to give crude 4-bromo-3,5-dimethyl-1H-pyrrole-2-carboxylic acid (1.2 g) which was used directly in the next step.

1. temperatureheated
2. temperatureunder reflux for 5 h
3. additionwas added dropwise
4. temperaturerefluxing
5. waitwas continued for 3 h
6. temperatureAfter cooling to RT the mixture
7. additionwas poured
8. customonto crushed ice
9. extractionextracted with DCM
10. filtrationThe combined organic phases were filtered through a plug of diatomaceous earth
11. concentrationconcentrated under reduced pressure