Synthesis
General procedure for the synthesis of 3-cyano-5-hydroxypyridine from 5-methoxynicotinonitrile: 1 g of 5-methoxynicotinonitrile (7.46 mmol) was mixed with 8.62 g of pyridine hydrochloride, and the reaction was heated at 200 °C for 2 hours. After completion of the reaction, the crude product was diluted with water and extracted several times with ether. The aqueous phase was alkalized by addition of sodium bicarbonate and extracted again with ether. The organic phases were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give 850 mg of 5-hydroxynicotinonitrile as a beige solid in 95% yield. The product was analyzed by LC-MS: m/z 120.94 (M+H+). 1H NMR (400 MHz, DMSO-d6): δ 10.79 (s, 1H, OH), 8.46 (s, 1H, Harom.), 8.42 (s, 1H, Harom.), 7.60 (s, 1H, Harom.).
References
[1] Patent: WO2012/101239, 2012, A1. Location in patent: Page/Page column 74
[2] Patent: US2013/85144, 2013, A1. Location in patent: Paragraph 0394; 0395; 0396
[3] Patent: EP2689778, 2014, A1. Location in patent: Paragraph 0238
[4] Patent: WO2014/16433, 2014, A1. Location in patent: Page/Page column 73
[5] Patent: WO2014/16434, 2014, A1. Location in patent: Page/Page column 72
