General procedure for the synthesis of 3,6-dibromo-4-methylpyridazine from 3,6-dichloro-4-methylpyridazine: 3,6-dichloro-4-methylpyridazine (10 g, 61.3 mmol) was suspended in a 30-33% hydrobromic acid solution in acetic acid (200 mL), and the reaction was allowed to stand for 24 hours at room temperature. Upon completion of the reaction, the precipitate was collected by filtration. The resulting precipitate was resuspended in dichloromethane and neutralized with saturated aqueous sodium bicarbonate. The organic layer was separated, washed with saturated aqueous sodium chloride solution and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure to give 3,6-dibromo-4-methylpyridazine (6.8 g, 44% yield). The product was characterized by 1H NMR (300 MHz, CDCl3): δ 7.50 (d, J = 1.2 Hz, 1H), 2.41 (d, J = 0.6 Hz, 3H); LC-MS showed a molecular ion peak of 253.1 [M + 3H].
