Synthesis
1. 5,6-Dichloropyridine-3-carboxylic acid (5 g) and thionyl chloride (3.10 g) were dissolved in methanol (20 mL) and the reaction was stirred overnight at 25 °C. 2. Upon completion of the reaction, cold water (100 mL) was added to the mixture and the mixture was neutralized with saturated sodium bicarbonate solution to pH neutral. 3. The aqueous layer was extracted using dichloromethane (2 x 100 mL). 4. The organic layers were combined, dried with anhydrous sodium sulfate and filtered to remove the drying agent. 5. The filtrate was concentrated under reduced pressure to give 5,6-dichloronicotinic acid methyl ester (5 g) as a white solid. 6. dried with anhydrous sodium sulfate and filtered to remove the desiccant. 5. The filtrate was concentrated under reduced pressure to give methyl 5,6-dichloronicotinate (5 g) as a white solid. 6. Mass Spectrometry (ESI): theoretical value of 205 for C7H5Cl2NO2; measured 206 [M + H]. 7.
References
[1] Patent: WO2008/7900, 2008, A1. Location in patent: Page/Page column 15; 26
[2] Patent: US2009/209540, 2009, A1. Location in patent: Page/Page column 15; 7
[3] Patent: WO2008/128968, 2008, A1. Location in patent: Page/Page column 51
[4] Journal of Medicinal Chemistry, 2006, vol. 49, # 12, p. 3719 - 3742
[5] Patent: WO2018/165385, 2018, A1. Location in patent: Paragraph 00391
