反应详情

A solution of 21.83 g of 2-hydrazinopyridine and 38.2 g of ethyl(ethoxymethylene)cyanoacetate dissolved in 150 ml of acetic acid and 50 ml of water was heated on a steam bath for approximately 16 hours. The reaction mixture was allowed to cool to room temperature and placed in a refrigerator whereupon crystals slowly formed. The precipitated solid was collected by filtration and washed with cold 50% aqueous ethanol to provide 23.62 g of 5-amino-1-(2-pyridinyl)-1H-pyrazole-4-carboxylic acid, ethyl ester. Yield 50.9%. MP=89°-91° C.

1. customslowly formed
2. filtrationThe precipitated solid was collected by filtration
3. washwashed with cold 50% aqueous ethanol