Synthesis
2,6-Dichloropyridine-N-oxide (Y-2) (8.20 g, 0.050 mol) was used as a raw material, which was dissolved in phosphorus trichloride (POCl3, 25 mL) and the reaction was carried out at reflux for 4 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue was carefully poured into crushed ice and extracted with petroleum ether (3 x 50 mL). The organic phases were combined, dried with anhydrous potassium carbonate (K2CO3), filtered and concentrated under reduced pressure. The crude product was purified by fast column chromatography using a mixed solvent of ethyl acetate/petroleum ether as eluent, resulting in colorless needle-like crystals of 2,4,6-trichloropyridine (Y-3) in 85% yield with a melting point of 32-33 °C. The final product was extracted from the crude product using a mixture of ethyl acetate/petroleum ether as eluent, and then dried with anhydrous potassium carbonate (3 × 50 mL).
References
[1] European Journal of Medicinal Chemistry, 2016, vol. 109, p. 294 - 304
[2] Patent: CN105294550, 2016, A. Location in patent: Paragraph 0045; 0048
[3] Bioorganic and Medicinal Chemistry, 2018, vol. 26, # 8, p. 2051 - 2060
[4] Chemical & Pharmaceutical Bulletin, 1986, vol. 34, # 9, p. 3658 - 3671
[5] Angewandte Chemie - International Edition, 2016, vol. 55, # 40, p. 12321 - 12324
