反应详情

Dissolve 2-dimethylaminomethylene-3-oxo-butyric acid ethyl ester (0.550 g, 2.96 mmol), pyridin-4-yl-hydrazine hydrochloride (0.454 g, 3.12 mmol) and triethylamine (0.435 mL, 3.12 mmol) in ethanol (12 mL) and reflux for 2 hr. Evaporate the mixture then dilute with saturated sodium bicarbonate and extract 3 times with ethyl acetate. Dry (sodium sulfate) the solution, filter and concentrate. Purify using silica gel chromatography, eluting with 50:50 ethyl acetate:hexane to give 5-methyl-1-pyridin-4-yl-1H-pyrazole-4-carboxylic acid ethyl ester as a tan solid (0.520 g, 76%). MS (ES): m/z=232 [M+H]+.

1. temperaturereflux for 2 hr
2. customEvaporate the mixture
3. additionthen dilute with saturated sodium bicarbonate
4. extractionextract 3 times with ethyl acetate
5. dry with materialDry (sodium sulfate) the solution
6. filtrationfilter
7. concentrationconcentrate
8. customPurify
9. washeluting with 50:50 ethyl acetate