121507-34-4

5-Isopropoxy-1H-pyrazol-3-amine pois involved with the synthesis and biol. evaluation of 2-(α-arylalkylamino)-4-(pyrazolylamino)pyrimidines as potent inhibitors of Trk kinases.

(Step 1) Preparation of 5-isopropoxy-1H-pyrazol-3-amine: methanesulfonic acid (25 mL) was slowly added to a solution of isopropanol (250 mL) containing 3-amino-5-hydroxypyrazole (25 g) with continuous stirring. The reaction mixture was heated to 120 °C and maintained for 2 days. Upon completion of the reaction, the reaction solution was cooled to room temperature and the solvent was subsequently removed by distillation under reduced pressure. Saturated aqueous sodium bicarbonate was added to the residue to neutralize the acid, followed by extraction with ethyl acetate. The organic phases were combined and dried over anhydrous sodium sulfate. The desiccant was removed by filtration and the organic phase was concentrated under reduced pressure to afford the target product 5-isopropoxy-1H-pyrazol-3-amine (5.35 g, 15% yield).

[1] Journal of Medicinal Chemistry, 2008, vol. 51, # 15, p. 4672 - 4684
[2] Patent: US2011/9622, 2011, A1. Location in patent: Page/Page column 38
[3] Patent: WO2008/135785, 2008, A1. Location in patent: Page/Page column 52-53