反应详情

温度

50 °C

To a solution of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-(furan-3-yl)pyrazole (0.5 g) in dimethylformamide (15 ml) and water (5 ml) was added sodium dithionite (0.112 g) and disodium hydrogen phosphate (0.067 g). The mixture placed in a 400 ml Parr vessel, which was evacuated, then charged with trifluoromethylbromide gas to 20 psi. The mixture was shaken and heated at 50° C., for 2.5 hours, then left at room temperature for 16 hours. The vessel was then evacuated, then charged with trifluoromethylbromide to 40 psi, then shaken and heated to 50° C. for a further 7 hours, then left at room temperature for 16 hours. Further sodium dithionite (0.120 g) and disodium hydrogen phosphate (0.080 g) was added, the vessel evacuated, then charged with trifluoromethylbromide to 40 psi, then shaken and heated to 50° C. as before for 9 hours, then left at room temperature for 48 hours. Further sodium dithionite (0.240 g) and disodium hydrogen phosphate (0.160 g) were added, the vessel was evacuated, then charged with trifluoromethylbromide to 45 psi, then shaken and heated to 50° C. as before for a further 9 hours. The mixture was filtered and then poured into ether (100 ml) and water (100 ml). The organic layer was separated, washed twice with water (50 ml), dried (Na2SO4), and evaporated. The residue was purified by column chromatography on silica gel (25 g) eluted with dichloromethane. Combination and evaporation of suitable fractions gave 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphenyl)-4-(2-trifluoromethylfuran-3yl)pyrazole as a white solid, m.p. 155-7° C.

1. customwas evacuated
2. additioncharged with trifluoromethylbromide gas to 20 psi
3. customThe vessel was then evacuated
4. additioncharged with trifluoromethylbromide to 40 psi
5. stirringshaken
6. temperatureheated to 50° C. for a further 7 hours
7. waitleft at room temperature for 16 hours
8. additionFurther sodium dithionite (0.120 g) and disodium hydrogen phosphate (0.080 g) was added
9. customthe vessel evacuated
10. additioncharged with trifluoromethylbromide to 40 psi
11. stirringshaken
12. temperatureheated to 50° C. as before for 9 hours
13. waitleft at room temperature for 48 hours
14. additionFurther sodium dithionite (0.240 g) and disodium hydrogen phosphate (0.160 g) were added
15. customthe vessel was evacuated
16. additioncharged with trifluoromethylbromide to 45 psi
17. stirringshaken
18. temperatureheated to 50° C. as before for a further 9 hours
19. filtrationThe mixture was filtered
20. additionpoured into ether (100 ml) and water (100 ml)
21. customThe organic layer was separated
22. washwashed twice with water (50 ml)
23. dry with materialdried (Na2SO4)
24. customevaporated
25. customThe residue was purified by column chromatography on silica gel (25 g)
26. washeluted with dichloromethane
27. customCombination and evaporation of suitable fractions