反应详情

Dibenzyl[2,4-difluoro-3-(4-pyridin-4-yl-1H-pyrazol-3-yl)-phenyl]-amine (prepared as described in Example 22) (4 g, 8.84 mmol) was suspended in DCM (44 mL) and 32% NaOH (44 mL) was added followed by tetrabutylammonium bromide (400 mg, 1.24 mmol, 0.14 eq). Neat ethyliodide (1.07 mL, 13.27 mmol, 1.5 eq) was then added and the biphasic mixture was vigorously stirred at room temperature for 1 h. By HPLC analysis at 254 nm the regioisomeric ratio was 55:45 in favour of the most polar N1-substituted pyrazole. The reaction mixture was then diluted with water (50 mL) and DCM (50 mL) and the two layers were separated. Aqueous phase was extracted with DCM (2×50 mL) and combined organic layers were washed with water (2×50 mL) and brine (50 mL), dried over Na2SO4 and evaporated to dryness. The two reagioisomers were separated by flash chromatography on silica gel (n-hexane/ethyl acetate 1:1) and the desired N1-ethylpyrazole was obtained as a white solid in 52% yield.

1. customthe two layers were separated
2. extractionAqueous phase was extracted with DCM (2×50 mL)
3. washwere washed with water (2×50 mL) and brine (50 mL)
4. dry with materialdried over Na2SO4
5. customevaporated to dryness
6. customThe two reagioisomers were separated by flash chromatography on silica gel (n-hexane/ethyl acetate 1:1)