Step 1: A suspension of 2-bromo-5-fluoro-3-nitropyridine (4.42 g, 20 mmol) with stannous chloride (SnCl2, 22.56 g, 100 mmol) in ethanol (EtOH, 40 mL) and concentrated hydrochloric acid (HCl, 40 mL) was heated to 60°C and reacted for 1 hour. After completion of the reaction, the reaction mixture was concentrated under reduced pressure. To the residue was added ethyl acetate (EtOAc, 100 mL) and saturated aqueous sodium bicarbonate (NaHCO3). The mixture was filtered through diatomaceous earth (Celite) and extracted with ethyl acetate (100 mL x 3). The organic layers were combined, washed sequentially with saturated sodium bicarbonate solution, water and brine, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure to give 3.1 g of 2-bromo-5-fluoropyridin-3-amine as a brown solid (80% yield). Mass spectrum (ESI): m/z = 191.1 [M + 1]+.
