Chemical Properties
Off-White Solid
Uses
A potent hypolipidemic agent. A possible inhibitor of phosphodiesterase 1
Uses
An impurity in the synthesis of Sildenafil.
Definition
ChEBI: 4-amino-1-methyl-3-propylpyrazole-5-carboxamide is a multi-substituted pyrazolecarboxamide used in the industrial synthesis of sildenafil. It is a member of pyrazoles and a monocarboxylic acid amide.
Synthesis
Step 7 Synthesis of 4-amino-1-methyl-3-n-propyl-1H-pyrazole-5-carboxamide: 1-methyl-4-nitro-3-propyl-1H-pyrazole-5-carboxamide (14.7 g, 69.3 mmol) was suspended in ethyl acetate (130 mL) and 10% palladium/carbon catalyst (3.3 g) was added. The reaction mixture was stirred overnight at 50 °C and 4 atm hydrogen pressure. Upon completion of the reaction, it was cooled to room temperature, the catalyst was removed by filtration, and the catalyst was washed with ethyl acetate. The combined filtrates were dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 4-amino-1-methyl-3-n-propyl-1H-pyrazole-5-carboxamide (13.8 g, 98% yield) as a white solid. The product was confirmed by 1H NMR (300 MHz, CDCl3): δ 4.12 (s, 3H), 2.84 (s, 2H), 2.55 (t, 2H, J = 7.2 Hz), 1.71-1.61 (m, 2H), 0.99 (t, 3H, J = 7.2 Hz); LC-MS showed m/z = 183 (MH)+.
References
[1] Patent: US2008/194529, 2008, A1. Location in patent: Page/Page column 57
[2] Patent: WO2014/131855, 2014, A1. Location in patent: Page/Page column 81
[3] Patent: WO2016/20307, 2016, A1. Location in patent: Page/Page column 51
[4] Patent: CN103044330, 2018, B. Location in patent: Paragraph 0025; 0031-0032; 0034-0035
[5] Patent: WO2015/114647, 2015, A1. Location in patent: Page/Page column 47; 48
