反应详情

Ethyl 5-ethyl-1-methylpyrazole-3-carboxylate (6.86 g) in ethanol (70 ml) was treated with sodium hydroxide (1.58 g) in water (30 ml) and heated under reflux for 6 h. The solution was concentrated and the aqueous phase washed with ethyl acetate before adding dichloromethane (50 ml). The solution was acidified with 5M hydrochloric acid, and the mixture exhaustively extracted with dichloromethane. The remaining undissolved solid was filtered off suspended in water and the pH adjusted to 6 with saturated sodium hydrogen carbonate. The solution was again extracted with dichloromethane. The combined organic layers were dried over anhydrous magnesium sulphate and concentrated to give the title compound as a white solid, (2.72 g, 47%); (Found: M+, 154.0742. C7H10N2O2 requires M, 154.0742); nmax (CH2Cl2) 3689 and 1760 cm- ; dH (CDCl3) 1.30 (3H, t, J7.4 Hz), 2.64 (2H, q, J7.4 Hz), 3.88 (3H, s) and 6.65 (1H, s).

1. temperatureheated
2. temperatureunder reflux for 6 h
3. concentrationThe solution was concentrated
4. washthe aqueous phase washed with ethyl acetate
5. additionbefore adding dichloromethane (50 ml)
6. extractionthe mixture exhaustively extracted with dichloromethane
7. filtrationThe remaining undissolved solid was filtered off
8. extractionThe solution was again extracted with dichloromethane
9. dry with materialThe combined organic layers were dried over anhydrous magnesium sulphate
10. concentrationconcentrated