反应详情

温度

-78 °C

To condensed isobutylene (1 ml) in a resealable glass tube was added 1-phenyl-3-carboxy-5-hydroxypyrazole (1 g; 4.9 mmol) in 30 ml of dioxane. The reaction mixture was cooled to -78° C. and 0.5 ml of conc. sulfuric acid was then added. The tube was sealed, stirred at room temperature for 6 hours, and cooled. The tube was opened, the mixture was neutralized and then basified (pH=12) with 2N NaOH solution, and extracted with ethyl acetate (3×). The combined organic layer was dried over magnesium sulfate and concentrated in vacuo to afford 431 mg of 1-phenyl-3-(t-butyloxycarbonyl)-5-hydroxypyrazole as a white solid.

1. customThe tube was sealed
2. temperaturecooled
3. extractionextracted with ethyl acetate (3×)
4. dry with materialThe combined organic layer was dried over magnesium sulfate
5. concentrationconcentrated in vacuo