1124383-03-4

1124383-04-5

Ethyl [(4,6-dichloropyridin-2-yl)carbamoyl]carbamate (2.9 g, 9.9 mmol) was used as a starting material, which was added to a methanol (MeOH) suspension of hydroxylamine hydrochloride (1.1 g, 16 mmol) and N,N-diisopropylethylamine (DIEA, 1.9 g, 15 mmol) in stirring. Subsequently, a solvent mixture of ethanol (EtOH) and methanol (1:1, 40 mL) was added in batches to form a solid suspension. The reaction mixture was stirred at room temperature for 2 hours, followed by warming to 80 °C and continued stirring for 18 hours. Upon completion of the reaction, the mixture was concentrated under reduced pressure and the residue was treated with water to give a paste-like solid. After filtration, the solid was dried in a vacuum oven at 40 °C for 18 h. The target product 5,7-dichloro-[1,2,4]triazolo[1,5-a]pyridin-2-amine (1.2 g, 60% yield) was finally obtained. The product was characterized by 1H NMR (DMSO-d6): δ 7.58 (d, J = 2.0 Hz, 1H), 7.35 (d, J = 2.0 Hz, 1H), 6.44 (s, 2H). Mass spectrum (m/z): [M + H]+ = 203.15.