1169563-99-8

To a 5 mL conical reaction vial was added tert-butyl 4-(2-cyanoacetyl)piperidine-1-carboxylate (348 mg, 1.379 mmol), hydrazine monohydrate (329.4 μL, 6.896 mmol) and anhydrous ethanol (4 mL). The reaction vial was sealed and the reaction was stirred in an oil bath at 80 °C for 20 h. The reaction was carried out under pressure and vaporized. After completion of the reaction, the solvent was removed by distillation under reduced pressure to afford tert-butyl 4-(5-amino-1H-pyrazol-3-yl)piperidine-1-carboxylate as a pale yellow foamy solid (367 mg, 99% yield).

[1] Patent: WO2009/111279, 2009, A1. Location in patent: Page/Page column 87
[2] Patent: WO2011/45344, 2011, A1. Location in patent: Page/Page column 88-89
[3] ACS Medicinal Chemistry Letters, 2015, vol. 6, # 6, p. 677 - 682
[4] Patent: WO2016/138532, 2016, A1. Location in patent: Paragraph 0252