反应详情

Ethyl 5-(4-benzyloxyphenyl)-2H-pyrazole-3-carboxylate (6 g) is added portionwise to a stirred suspension of sodium hydride (0.75 g) in tetrahydrofuran (250 mL) at room temperature. Stirring is continued at this temperature for a further 30 minutes when benzyl bromide (3.57 g) is added in one portion. The reaction mixture is heated to reflux for 5 hours, then evaporated in vacuo. The residue is treated with water (250 mL), the resulting yellow solid washed well with water, then dissolved in tetrahydrofuran and filtered to remove a small amount of insoluble white solid. The filtrate is evaporated and the residual yellow solid purified by flash chromatography on silica eluting initially with dichloromethane then with a mixture of ethyl acetate and dichloromethane (1:9 v/v) to give ethyl 2-benzyl-5-(4-benzyloxyphenyl)-2H-pyrazole-3-carboxylate (1.2 g) and ethyl 1-benzyl-5-(4-benzyloxyphenyl)-2H-pyrazole-3-carboxylate (2 g).

1. temperatureThe reaction mixture is heated
2. temperatureto reflux for 5 hours
3. customevaporated in vacuo
4. additionThe residue is treated with water (250 mL)
5. washthe resulting yellow solid washed well with water
6. dissolutiondissolved in tetrahydrofuran
7. filtrationfiltered
8. customto remove a small amount of insoluble white solid
9. customThe filtrate is evaporated
10. customthe residual yellow solid purified by flash chromatography on silica eluting initially with dichloromethane
11. additionwith a mixture of ethyl acetate and dichloromethane (1:9 v/v)