Stage 1(b): synthesis of 2-bromo-6-iodo-3-methoxypyridine (3). Potassium carbonate (K2CO3, 6.22 g, 45.1 mmol) and iodomethane (CH3I, 24.6 g, 10.77 mL, 173.3 mmol) were sequentially added to a solution of N,N-dimethylformamide (DMF, 30 mL) in which 2-bromo-6-iodo-pyridin-3-ol (2, 14.9 g, 49.5 mmol) was dissolved. The reaction mixture was heated and stirred at 100 °C for 2 h and subsequently cooled to room temperature. Reaction termination was achieved by addition of water (H2O) and stirring was continued for 30 min. The precipitate formed was collected by filtration, washed with water and dried in air to give light brown solid product 3 (15.7 g, 100% yield). The product was characterized by the following data: 1H NMR (CDCl3) δ 7.61 (d, 1H, J = 8.4 Hz), 6.86 (d, 1H, J = 8.4 Hz), 3.93 (s, 3H); mass spectral observation m/z = 314 (M + 1), 315.
