Bromine → 6-Bromo-2-nitropyridin-3-amine

To a stirred suspension of 2-nitro-pyridin-3-ylamine (5.06 g, 36.40 mmol) and sodium acetate (2.99 g, 36.46 mmol) in acetic acid (40 mL), a solution of bromine (2.5 mL, 48.79 mmol) in acetic acid (8 ml) was added drop-wise and the reaction mixture was stirred overnight. The acetic acid was removed under reduced pressure. The residue was cooled to 0° C., neutralized with saturated sodium bicarbonate solution to adjust the pH to ˜7, and extracted with ethyl acetate (4×50 mL). The combined organic extracts were washed with brine, dried over anhydrous Na2SO4, and concentrated under reduced pressure. The residue was triturated with ethyl acetate to afford compound (5) (5.1 g) as a yellow solid.