33332-29-5

2032-35-1

76537-23-0

2-Amino-5-chloropyrazine (2.6 g, 20 mmol) and 2-bromo-1,1-diethoxyethane (12.0 g, 60.89 mmol) were used as starting materials and dissolved in 30 mL of isopropanol. Subsequently, hydrogen bromide solution (10.5 g, 62.22 mmol) was added to the reaction system and the reaction was stirred at 80°C overnight. Upon completion of the reaction, the mixture was cooled to room temperature and the pH was adjusted with sodium bicarbonate to 8. Next, extraction was carried out with dichloromethane, the organic phases were separated and combined, and the crude product was concentrated under reduced pressure. Purification by Combi-flash fast column chromatography (eluent ratio: dichloromethane:methanol = 90:10:70:30) afforded a brown solid product, 6-chloroimidazo[1,2A]pyrazine (2.3 g), in a yield of 49.75% and a purity of 96.63%. The product did not need further purification and could be used directly in the subsequent reaction.