反应详情

To ethyl 2-(ethoxymethylene)acetoacetate (25.1 g) prepared according to a method described in J. Chem. Soc. Perkin trans. I, 1875 (1988), were added 1N hydrochloric acid aqueous solution (135 ml) and an ethanol solution (135 ml) of 3,5-dichloropyridin-2-ylhydrazine (24.02 g) described above, stirred at reflux temperature for three hours and left to stand at room temperature. Water was added to the reaction solution, the precipitated solid was collected by filtration and purified with a mixed solvent of ethyl acetate and n-hexane to give 1-(3,5-dichloropyridin-2-yl)-5-methyl-1H-pyrazole-4-carboxylic acid ethyl ester.

1. temperatureat reflux temperature for three hours
2. waitleft
3. customto stand at room temperature
4. filtrationthe precipitated solid was collected by filtration
5. custompurified with a mixed solvent of ethyl acetate and n-hexane