General procedure for the synthesis of 2-chloro-6-methoxyquinoline from 6-methoxyquinolin-2(1H)-one: 6-methoxyquinolin-2-ol (400 mg, 2.29 mmol) was dissolved in phosphorus trichloride (5.0 mL) and the reaction was carried out at reflux for 2 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. The residue was dissolved in ethyl acetate (50 mL) and the organic layer was washed sequentially with saturated sodium bicarbonate solution (30 mL × 2). The organic layer was dried over anhydrous sodium sulfate, filtered and concentrated to give the crude product. The crude product was purified by silica gel column chromatography (petroleum ether/ethyl acetate = 10:1) to afford 2-chloro-6-methoxyquinoline (380 mg, 86% yield) as a white solid.1H NMR (CDCl3, 400 MHz): δ 7.92 (d, J = 8.4 Hz, 1H), 7.85 (d, J = 9.2 Hz, 1H), 7.32-7.25 ( m, 2H), 7.00 (d, J = 2.4 Hz, 1H), 3.86 (s, 3H).
