Synthesis
General procedure for the synthesis of 5-bromo-2-chloro-6-methylpyridin-3-amine from 2-chloro-3-nitro-5-bromo-6-methylpyridine: In a 250 mL round-bottomed flask, 3-bromo-6-chloro-2-methyl-5-nitropyridine (1.5 g, 5.97 mmol, commercially available) was added and dissolved in ethyl acetate (20 mL). To this solution was added ammonium chloride (3.19 g, 59.65 mmol) dissolved in water (10 mL) and stirred for 10 minutes at room temperature. Zinc powder (2.340 g, 35.79 mmol) was then quickly added and the resulting reaction mixture was refluxed at 55°C for 6 hours. After completion of the reaction, the mixture was filtered through diatomaceous earth and concentrated in vacuum. The residue was partitioned between ethyl acetate (150 mL) and water (75 mL). The organic layer was dried with anhydrous sodium sulfate and subsequently concentrated under vacuum. The crude product was purified by fast column chromatography using an Argonaut purification system to afford 5-bromo-2-chloro-6-methylpyridin-3-amine (0.500 g, 37.8% yield) as a white solid using a hexane solution of 12% ethyl acetate as eluent. Mass spectrum (ES+): m/z 222, molecular formula C6H6BrClN2.
