Compound 21 (8.3 g, 0.04 mol) was added to thionyl chloride (80 mL) and heated to reflux for 3 hours. Upon completion of the reaction, excess thionyl chloride was removed by distillation under reduced pressure. Acetone (240 mL) was added to the residue with stirring at 25 °C and ammonia was added slowly and dropwise, the reaction lasted for 10 min. The reaction mixture was concentrated to one-fourth of the original volume and the concentrate was poured into 200 g of crushed ice, precipitating a yellow solid. The solid was collected by filtration to give 4.5 g of the target product 2-chloro-5-nitro-3-pyridine carboxamide in 54.2% yield. The melting point of the product was 177.3-178.2 °C.
References
[1] Russian Chemical Bulletin, 2005, vol. 54, # 8, p. 1907 - 1914 [2] Patent: EP2366691, 2011, A1. Location in patent: Page/Page column 10 [3] Antimicrobial Agents and Chemotherapy, 2014, vol. 58, # 1, p. 55 - 60
