反应详情

To a solution of benzyl 3-(methylamino)-2-(trifluoroacetyl)but-2-enoate (90 g, 300 mmol) in a mixture of THF (900 mL) and acetic acid (100 mL) was added hydrazine monohydrate (14.6 mL, 300 mmol) over a 5 min period. The reaction mixture was heated to reflux for 3 hours, allowed to cool to room temperature and the solvents were evaporated in vacuo to afford a bright yellow mass. The mass was dissolved in EtOAc (1 L) and water (1 L) with gentle heating, allowed to cool to room temperature and the aqueous layer was neutralized to pH 7-8 with NaHCO3. This mixture was transferred to a 3-L separating funnel, the layers were mixed vigorously, separated and the organic layer was washed with water (3×500 mL) dried (MgSO4), filtered and evaporated in vacuo to give benzyl 3-methyl-5-(trifluoromethyl)-1H-pyrazole-4-carboxylate as an off-white solid in 89% yield 74 g that was used without further purification.

1. temperatureThe reaction mixture was heated
2. temperatureto reflux for 3 hours
3. customthe solvents were evaporated in vacuo
4. customto afford a bright yellow mass
5. temperatureto cool to room temperature
6. customseparating funnel
7. additionthe layers were mixed vigorously
8. customseparated
9. washthe organic layer was washed with water (3×500 mL)
10. dry with materialdried (MgSO4)
11. filtrationfiltered
12. customevaporated in vacuo