Synthesis
General procedure for the synthesis of 3-amino-5-methyl-1H-pyrazole-4-carbonitrile from 2-(1-ethoxyethylidene)malononitrile: Hydrazine hydrate (4.5 mL, 92 mmol) was added to a 50 mL round-bottomed flask and stirred at room temperature. Subsequently, 2-(1-ethoxyethylidene)malononitrile (5.0 g, 37 mmol) was added in batches. When half of the ingredients were added, the flask was transferred to an ice water bath to continue the reaction. Upon completion of the addition, a precipitate was observed to form, at which point the reaction flask was removed from the ice-water bath and heated to reflux for 2 hours, after which it was cooled to room temperature. The reaction mixture was briefly cooled in an ice water bath and subsequently sonicated to promote crystallization. The solid product was collected by filtration, washed with water and dried under vacuum to give the final 3-amino-5-methyl-1H-pyrazole-4-carbonitrile (2.69 g, 60% yield).1H NMR (300 MHz, d6-DMSO) δ 3.31 (s, 3H).
References
[1] Patent: WO2018/89786, 2018, A1. Location in patent: Paragraph 00148
[2] Patent: US2012/202785, 2012, A1. Location in patent: Page/Page column 259
[3] Journal of Organic Chemistry, 1956, vol. 21, p. 1240,1242
[4] Bioorganic and Medicinal Chemistry Letters, 2000, vol. 10, # 8, p. 821 - 826
[5] Patent: US2006/135526, 2006, A1. Location in patent: Page/Page column 21
