Step A: Preparation of 2-bromo-5-methylpyridin-3-amine: acetic acid (5 mL) was slowly added dropwise to iron powder (1.11 g, 19.8 mmol) and the mixture was heated to 80 °C. Subsequently, a solution of acetic acid (5 mL) of 2-bromo-5-methyl-3-nitropyridine (1.0 g, 4.61 mmol) was added dropwise over a period of 20 min, and stirring was continued for 30 min after completion of the dropwise addition. The reaction mixture was stirred at room temperature for 16 hours, then diluted with ethyl acetate (20 mL) and filtered through diatomaceous earth (Celite). The diatomaceous earth pad was washed well with ethyl acetate, the filtrates were combined and concentrated under reduced pressure. The residue was slowly added to saturated sodium bicarbonate solution (50 mL), followed by addition of solid sodium bicarbonate in batches until the acetic acid was completely neutralized. The mixture was extracted with ethyl acetate (3 x 30 mL), and the combined organic phases were washed with brine (20 mL), dried over anhydrous sodium sulfate, filtered and concentrated to afford 2-bromo-5-methylpyridin-3-amine (799 mg, 93% yield) as a bright yellow crystalline solid, which darkened to a greenish color after drying under vacuum. Mass spectrum (APCI) m/z = 188.9 (M + H).
