Sodium methanolate (0.068 g, 1.25 mmol) was added batchwise to a stirred solution of 4,6-dichloropyridine-3-carbaldehyde (0.2 g, 1.14 mmol) in methanol (10 mL) at 0 °C. The reaction mixture was slowly warmed to room temperature (about 5 hours) and stirring was continued at room temperature for 16 hours. Upon completion of the reaction, the solvent was removed by distillation under reduced pressure and the residue was dissolved in dichloromethane. Insoluble solids were removed by filtration and the filtrate was purified by fast silica gel column chromatography with an elution gradient of 0 to 50% ethyl acetate in heptane solution. The purified grades were collected and concentrated under reduced pressure to give 6-chloro-4-methoxynicotinaldehyde (0.111 g, 57% yield) as a white solid.1H NMR (500 MHz, CDCl3, 22 °C) δ 4.02 (3H, s), 6.97 (1H, s), 8.69 (1H, s), 10.37 (1H, d). Mass spectrum (ESI+): m/z 172 [M+H]+.
