General procedure for the synthesis of pyridazin-3-amine from 3-amino-6-chloropyridazine:
(1) 6-chloropyridazin-3-amine (5.00 g, 38.6 mmol), tetrahydrofuran (240 mL), sodium hydroxide (8.00 g, 200 mmol), water (32 mL), and 10% palladium-carbon catalyst (500 mg) were mixed, and the reaction was stirred at room temperature in a hydrogen atmosphere for 2 days. After completion of the reaction, the insoluble material was removed by filtration and the filtrate was concentrated. The residue was dissolved in methanol (100 mL), filtered again to remove insoluble matter, and the filtrate was concentrated to quantitatively obtain the target product pyridazin-3-amine as a solid.
1H-NMR (DMSO-d6) δ: 2.51 (2H, broad peak), 6.46-6.49 (1H, multiple peaks), 6.93-6.97 (1H, multiple peaks), 8.06-8.08 (1H, multiple peaks).
