Synthesis
a) Mix 2-hydroxy-5-fluoropyridine (1.20 g, 10.6 mmol) with concentrated sulfuric acid (2.7 mL), cool in an ice bath and stir. A mixture consisting of concentrated sulfuric acid (1 mL) and fuming nitric acid (1 mL) was slowly added dropwise. After the dropwise addition was completed, the reaction mixture was gradually warmed to room temperature and subsequently heated to 85°C for 2 hours. Upon completion of the reaction, the mixture was cooled and poured into ice water. The precipitate was collected by filtration and dried to give 2-hydroxy-3-nitro-5-fluoropyridine (0.72 g, 43% yield) as a yellow solid.LRMS (m/z): 157 (M-1)+.1H NMR (300 MHz, DMSO-d6) δ: 8.28 (s, 1H), 8.67 (s, 1H).
References
[1] Patent: EP2527344, 2012, A1. Location in patent: Page/Page column 22
[2] Patent: WO2012/160030, 2012, A1. Location in patent: Page/Page column 66
[3] Patent: WO2006/114706, 2006, A1. Location in patent: Page/Page column 45
[4] Journal of Heterocyclic Chemistry, 1996, vol. 33, # 2, p. 287 - 293
[5] Patent: US2004/110785, 2004, A1. Location in patent: Page 211
