Synthesis
The reaction was carried out at 100 °C for 5 h with stirring, using 4,6-dimethyl-3-nitropyridin-2(1H)-one (9.0 g, 53.5 mmol) as raw material, which was dissolved in phosphorous trichloride (50 mL). Upon completion of the reaction, the reaction solution was cooled to room temperature and subsequently concentrated under reduced pressure to remove the solvent. The resulting residue was dissolved in dichloromethane (50 mL) and the pH was adjusted to >7 by slow dropwise addition of saturated sodium bicarbonate solution at 0 °C. The organic phase was separated, dried over anhydrous sodium sulfate and filtered. The filtrate was concentrated under reduced pressure and ground with petroleum ether to give 2-chloro-4,6-dimethyl-3-nitropyridine (9.0 g, 90% yield) as a brown solid. lc-MS m/z: 187.1 [M + H]+; purity (214 nm): 96%; tR = 1.76 min.
References
[1] Patent: WO2006/95268, 2006, A1. Location in patent: Page/Page column 28
[2] Patent: US2003/236260, 2003, A1. Location in patent: Page 21
[3] Patent: WO2017/192930, 2017, A1. Location in patent: Paragraph 00539
[4] Patent: WO2005/102389, 2005, A2. Location in patent: Page/Page column 95-96
[5] Patent: US2002/77329, 2002, A1
