942185-01-5

General procedure for the synthesis of 1H-pyrazolo[3,4-b]pyridin-5-amine from 5-nitro-7-azaindazole: 5-nitro-1H-pyrazolo[3,4-b]pyridine (308 mg, 1.876 mmol) was dissolved in a mixed solvent of ethanol and tetrahydrofuran, and 10% palladium-carbon-catalyst (40 mg) was added. The reaction mixture was stirred for 15 hours under hydrogen atmosphere. After completion of the reaction, the catalyst was removed by diatomaceous earth filtration and the filtrate was purified by column chromatography to afford the target product 1H-pyrazolo[3,4-b]pyridin-5-amine (73 mg) in 89% yield.

[1] Patent: WO2013/13816, 2013, A1. Location in patent: Page/Page column 73; 74
[2] Patent: US2013/29995, 2013, A1. Location in patent: Paragraph 0374-0375
[3] European Journal of Medicinal Chemistry, 2017, vol. 131, p. 1 - 13
[4] Patent: WO2007/70398, 2007, A1. Location in patent: Page/Page column 249