Synthesis
To an ice-cold solution of 2,6-dichloroisonicotinic acid (10 g, 52 mmol) in ethanol (100 mL) was slowly added concentrated sulfuric acid (5 mL). The reaction mixture was heated to reflux and held for 12 hours. Upon completion of the reaction, the solvent was evaporated under reduced pressure. The residue was cooled in an ice bath, neutralized to pH neutral with sodium bicarbonate solution and subsequently extracted with ethyl acetate. The organic layers were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give ethyl 2,6-dichloro-isonicotinate (11 g, 96% yield).
References
[1] Patent: WO2017/4609, 2017, A1. Location in patent: Paragraph 0265
[2] Chemistry - A European Journal, 2010, vol. 16, # 9, p. 2830 - 2842
[3] Journal of the Chemical Society, 1897, vol. 71, p. 1082
[4] Journal of the Chemical Society, 1898, vol. 73, p. 441
[5] Journal of Medicinal Chemistry, 1990, vol. 33, # 6, p. 1667 - 1675
