反应详情

Part A. In a flame-dried 1-L flask was combined anhydrous methyl alcohol (1.4 L), 4-methoxyphenylhydrazine hydrochloride (25 g, 140 mmol), 4,4,4-trifluoro-1-(2-furyl)-1,3-butanedione (30 g, 140 mmol), and trifluoroacetic acid (1.1 mL, 14 mmol). The resulting red slurry was maintained at rt for 14 h. A 50% solution of isopropyl alcohol/water (500 mL) was then added, and the mixture was stirred vigorously for 5 min. The mixture was filtered; additional material precipitated from the filtrate upon standing, and the new mixture was filtered. After another 3 h, the resulting filtrate was filtered a third time, and the combined beige solid was oven dried under vacuum to afford 5-(2-furyl)-1-(4-methoxy-phenyl)-3-(trifluoromethyl)-1H-pyrazole (42 g, 96%) as a light brown solid. 1H NMR (CDCl3) δ 7.42(m, 1H), 7.35 (d, 2H), 6.98 (d, 2H), 6.89 (s, 1H), 6.33 (dd, 1H), 5.90 (d, 1H), 3.88 (s, 3H).

1. filtrationThe mixture was filtered
2. customadditional material precipitated from the filtrate
3. filtrationthe new mixture was filtered
4. waitAfter another 3 h
5. filtrationthe resulting filtrate was filtered a third time
6. customdried under vacuum