The general procedure for the synthesis of 6-iodopyridazin-3-amine from 3-amino-6-chloropyridazine was as follows: 6-chloropyridazin-3-amine (3.7 g, 28.56 mmol) was placed in a 100 mL round-bottomed flask fitted with a reflux condenser tube and a magnetic stirrer. Subsequently, hydrogen iodide (57 wt% aqueous solution, 20 mL, 265.96 mmol) was added to the flask, and the resulting dark brown solution was heated and stirred under mild reflux conditions for 6 hours. After completion of the reaction, the mixture was cooled to room temperature. The crude product was collected by filtration and the reaction vessel was washed with ice-cooled water (2 x 30 mL) and the washings were combined onto a filter cake. The resulting solid was partitioned between ethyl acetate and 2N aqueous sodium hydroxide solution. The organic layer was washed with aqueous sodium hydroxide, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure to give 6-iodopyridazin-3-amine (4.10 g, 65% yield) as a solid. The product was characterized by 1H NMR (400 MHz, DMSO, 27 °C): δ 6.52 (2H, s), 6.55 (1H, d), 7.54 (1H, d).
