56022-07-2

Ethyl 2,4-dichloro-6-methylpyridine-3-carboxylate (1.0 g, 4.3 mmol) was used as a raw material, which was dissolved in a mixed solvent of water (1.7 mL) and methanol (1.5 mL) with NaOH (342 mg, 8.6 mmol). The reaction mixture was heated to 80 °C and the reaction was stirred at this temperature for 4 hours. Upon completion of the reaction, the reaction solution was acidified to pH < 7 with 50% H2SO4, followed by filtration to collect the precipitate. The solid product was washed with cold water and dried to give 2,4-dichloro-6-methylpyridine-3-carboxylic acid (582 mg, 66% yield). The product was analyzed by LCMS with a retention time (RT) of 0.70 min and a molecular ion peak (MH+) of 206.2.

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[3] Patent: WO2017/139778, 2017, A1. Location in patent: Paragraph 00272