Synthesis
The general procedure for the synthesis of ethyl 2-(6-chloropyridin-3-yl)acetate from ethanol and 2-chloropyridine-5-acetic acid was as follows: to an ethanolic solution of 6-chloro-3-pyridineacetic acid (1 g, 5.83 mmol) was slowly added concentrated sulfuric acid (1.6 mL). The reaction mixture was heated to reflux and kept for 4 hours. Upon completion of the reaction, the mixture was cooled to room temperature and concentrated in a rotary evaporator to remove most of the ethanol. The concentrated residue was dissolved in ethyl acetate and subsequently washed with saturated sodium bicarbonate solution to neutralize the residual acid. The organic phase was dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give the crude product. Finally, the crude product was purified by silica gel column chromatography to afford ethyl 2-(6-chloropyridin-3-yl)acetate (1.1 g, 95% yield).
References
[1] Patent: WO2013/13817, 2013, A1. Location in patent: Page/Page column 99
[2] Patent: WO2013/13815, 2013, A1. Location in patent: Page/Page column 147
[3] Patent: US2013/29961, 2013, A1. Location in patent: Paragraph 0664
[4] Patent: US2013/29962, 2013, A1. Location in patent: Paragraph 0815
[5] Chemical Communications, 2015, vol. 51, # 84, p. 15446 - 15449
