1034667-22-5

The general procedure for the synthesis of 5-fluoro-1H-pyrazolo[3,4-b]pyridin-3-amine from 2-chloro-5-fluoro nicotinonitrile was as follows: to a solution of 2-chloro-5-fluoro nicotinonitrile (50 g, 321.7 mmol) in 1-butanol (1 L) was added hydrazine monohydrate (150 mL, 3.2 mol) and the mixture was refluxed for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature and concentrated. The resulting precipitate was washed sequentially with water (twice) and ether (twice) and subsequently dried under vacuum overnight to afford 5-fluoro-1H-pyrazolo[3,4-b]pyridin-3-amine (44 g, 88% yield) as a yellow solid.1H NMR (DMSO-d6, 300 MHz) data were as follows: δ 5.53 (s, 2H); 7.94 (dd, 1H); 8.35 (dd, 1H); 12.02 (s, 1H).

[1] Patent: WO2008/77086, 2008, A1. Location in patent: Page/Page column 56; 58
[2] Patent: WO2009/18415, 2009, A1. Location in patent: Page/Page column 35-37
[3] Patent: US2011/20377, 2011, A1. Location in patent: Page/Page column 12; 13
[4] Patent: WO2008/112642, 2008, A1. Location in patent: Page/Page column 51-52
[5] Patent: WO2008/112646, 2008, A1. Location in patent: Page/Page column 51