6775-78-6

18087-76-8

The general procedure for the synthesis of 6-chloro-3-nitroimidazo[1,2-b]pyridazine from 6-chloroimidazo[1,2-b]pyridazine was as follows: 6-chloroimidazo[1,2-b]pyridazine (4.95 g, 31.6 mmol) was dissolved in 60 mL of concentrated sulfuric acid and cooled in an ice bath. Nitric acid (9.9 mL, 158 mmol) was added slowly and dropwise under stirring conditions. The reaction mixture was stirred at 0 °C for 30 min, followed by continued stirring at room temperature for 4.5 h to ensure complete reaction. Upon completion of the reaction, the mixture was slowly poured into ice water and the resulting aqueous solution was neutralized with 50% aqueous sodium hydroxide. Subsequently, extraction was carried out with ethyl acetate (3 x 400 mL). The organic phases were combined and washed sequentially with water (2 x 400 mL) and saturated saline (400 mL). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to afford the target product 6-chloro-3-nitroimidazo[1,2-b]pyridazine (5.7 g, 91% yield) in the form of light yellow powder.