反应详情

Under a nitrogen purge, a suspension or 2-(p-chlorophenyl)-5-(trifluoromethyl)pyrrole-3-carbonitrile (1.6 g; 0.005 mol) in acetic acid (25 mL) is heated, all the material dissolving to a clear solution at about 60° C. A solution of bromine (0.8 mL; 0.015 mol) in acetic acid (10 mL) is added dropwise over 15 minutes to the refluxing solution. The solution is refluxed 6 hours then allowed to stir 18 hours at room temperature. The HPLC of the reaction mixture shows about 80% conversion to product. The mixture is heated back to reflux and more bromine (0.5 mL; 0.01 mol) in acetic acid (5 mL) is added dropwise. After refluxing another 3 hours, the aliquot shows >95% conversion to product. The reaction is cooled, and solvent removed under reduced pressure on a rotary evaporator to obtain a dark grey solid. Toluene is added to the mixture and removed under reduced pressure, but the odor of acetic acid still remains. The entire material is dissolved in hot toluene (75 mL) to a turbid solution which is treated with DARCO filter and filtered. The light pink solution deposits a white solid upon cooling to ambient. After cooling in the freezer, the solid is collected by filtration, washed with hexanes, and dried on the filter. Further drying in a vacuum oven at 45° C. provides the product (1.2 g; app. 60% theoretical); m.p. 247°-250° C.(dec.).

1. customUnder a nitrogen purge
2. dissolutionall the material dissolving to a clear solution at about 60° C
3. temperatureThe solution is refluxed 6 hours
4. temperatureThe mixture is heated back
5. temperatureto reflux
6. temperatureAfter refluxing another 3 hours
7. temperatureThe reaction is cooled
8. customsolvent removed under reduced pressure on a rotary evaporator
9. customto obtain a dark grey solid
10. customremoved under reduced pressure
11. dissolutionThe entire material is dissolved in hot toluene (75 mL) to a turbid solution which
12. additionis treated with DARCO
13. filtrationfilter
14. filtrationfiltered
15. temperatureThe light pink solution deposits a white solid upon cooling to ambient
16. temperatureAfter cooling in the freezer
17. filtrationthe solid is collected by filtration
18. washwashed with hexanes
19. customdried on the filter
20. customFurther drying in a vacuum oven at 45° C.
21. customprovides the product (1.2 g