Synthesis
b) Synthesis of 2-acetamido pyridine-4-carboxylic acid (3): 214.0 g of 2-(acetamido)-4-methylpyridine (2) was added in batches to an aqueous solution of 160 g of potassium permanganate at 50 °C while maintaining stirring. An additional 360 g of potassium permanganate was added in batches over a period of 1 hour, during which the temperature of the reaction mixture needed to be controlled not to exceed 90 °C. After completion of the reaction, stirring was continued for 1.5 hours, followed by thermal filtration. The pH of the filtrate was adjusted to 3-4 with concentrated hydrochloric acid, and the white precipitate precipitated was 2-acetylaminopyridine-4-carboxylic acid (3). After separation by filtration and drying under vacuum conditions, 108.0 g of product was obtained in 42% yield.
References
[1] Journal of Organic Chemistry, 2003, vol. 68, # 11, p. 4527 - 4530
[2] Patent: WO2006/89798, 2006, A1. Location in patent: Page/Page column 25
[3] Patent: EP1894925, 2008, A1. Location in patent: Page/Page column 14; 41
[4] Journal of Medicinal Chemistry, 2017, vol. 60, # 16, p. 6942 - 6990
[5] Farmaco, Edizione Scientifica, 1958, vol. 13, p. 485,487
