反应详情

A solution of ethyl 5-bromo-1-methyl-1H-pyrazole-4-carboxylate (2.00 g, 8.58 mmol) in tetrahydrofuran (30 mL) at 0° C. was treated with diisobutylaluminum hydride (1 M solution in tetrahydrofuran, 18.9 mL, 18.9 mmol), and the mixture was allowed to warm to room temperature and stir for 18 hours. Saturated aqueous sodium potassium tartrate solution was added, and stirring was continued for 4 hours. The aqueous layer was extracted with ethyl acetate, and the combined organic layers were dried over magnesium sulfate, filtered, and concentrated under reduced pressure. Purification via silica gel chromatography (Eluent: 100:1 ethyl acetate/methanol) afforded the product. Yield: 1.63 g, 8.53 mmol, 99%. LCMS m/z 192.9 (M+1). 1H NMR (400 MHz, CDCl3) δ 2.44 (s, 1H), 3.84 (s, 3H), 4.48 (s, 2H), 7.51 (s, 1H).

1. stirringstirring
2. waitwas continued for 4 hours
3. extractionThe aqueous layer was extracted with ethyl acetate
4. dry with materialthe combined organic layers were dried over magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure
7. customPurification via silica gel chromatography (Eluent: 100:1 ethyl acetate/methanol)
8. customafforded the product