General procedure for the synthesis of 4-chloro-7-methoxyquinoline-3-carboxylic acid from ethyl 4-chloro-7-methoxyquinoline-3-carboxylate: to a stirred suspension of ethyl 4-chloro-7-methoxyquinoline-3-carboxylate (11.1 g, 41 mmol) in ethanol (100 ml) was added 2M NaOH solution (100 ml). The reaction mixture was stirred at room temperature for 3 days. Upon completion of the reaction, the reaction mixture was diluted with water (100 ml), cooled in an ice/water bath and acidified by dropwise addition of concentrated hydrochloric acid to pH 4. The precipitated solid product was collected by filtration, washed with water and dried in a vacuum drying gun at 50 °C to afford 4-chloro-7-methoxyquinoline-3-carboxylic acid (8.8 g, 89% yield).1H NMR (400 MHz, DMSO- d6) δ 3.98 (3H, s), 7.48 (1H, dd, J=9.2 and 2.5 Hz), 7.52 (1H, d, J=2.5 Hz), 8.28 (1H, d, J=9.2 Hz), 9.11 (1H, s).
