General procedure for the synthesis of 3-bromo-5-methoxypyridine from 3-bromo-5-methoxypyridine: 3-bromo-5-methoxypyridine (500 mg, 2.66 mmol), ammonium hydroxide (15 mL), and cobalt sulfate pentahydrate (33 mg, 0.13 mmol) were placed in a hermetically sealed tube and heated in a microwave reactor for 20 hours at 140 °C. After completion of the reaction, the reaction mixture was cooled to room temperature and the crude product was subjected to liquid-liquid separation between ethyl acetate and water. The organic layer was washed sequentially with water (3 times) and saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to give 84 mg of solid product in 25% yield. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 7.72 (d, J = 5.4 Hz, 2H), 6.51 (t, J = 2.4 Hz, 1H), 3.79 (s, 3H) ppm; HPLC-MS: m/z 125.0.
