反应详情

To a mixture of 12.0 g of ethyl 2-(3-chloro-2-pyridinyl)-5-oxo-3-pyrazolidinecarboxylate, 90 ml of acetonitrile and 4.8 ml of sulfuric acid was added 14.5 g of potassium persulfate. The resulting mixture was heated to reflux for 3.5 hours. The reaction mixture was allowed to cool to room temperature, and filtered. Water was poured into the filtrate, and the mixture was extracted with methyl tert-butyl ether three times. The organic layers were combined, washed with an aqueous saturated sodium chloride solution, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The resulting residue was subjected to silica gel chromatography to obtain 7.23 g of ethyl 1-(3-chloro-2-pyridinyl)-3-hydroxy-1H-pyrazole-5-carboxylate of the formula:

1. temperatureThe resulting mixture was heated
2. temperatureto reflux for 3.5 hours
3. filtrationfiltered
4. additionWater was poured into the filtrate
5. extractionthe mixture was extracted with methyl tert-butyl ether three times
6. washwashed with an aqueous saturated sodium chloride solution
7. dry with materialdried over anhydrous magnesium sulfate
8. concentrationconcentrated under reduced pressure