7400-27-3

94-05-3

112779-14-3

Step 1. A mixture of tert-butylhydrazine hydrochloride (10 g, 80.3 mmol), ethyl ethoxymethoxycarbonylcyanoacetate (13.6 g, 80.4 mmol), and anhydrous sodium acetate (8.2 g, 100 mmol) was stirred and reacted at reflux for 16 hours in 100 mL of ethanol. After completion of the reaction, the reaction solution was poured into ice water. The aqueous phase was extracted three times with dichloromethane and the organic phases were combined. The organic phase was washed sequentially with water and saturated brine solution and then dried with anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure to give ethyl 5-amino-1-tert-butyl-1H-pyrazole-4-carboxylate (13 g, 77% yield).