To a solution of 2,6-dichloro-4-hydroxybenzaldehyde (225 mg, 1.18 mmol) in N,N-dimethylformamide (DMF, 2.0 mL) was added potassium carbonate (0.81 g, 5.9 mmol) and iodomethane (1.47 mL, 23.6 mmol). The reaction mixture was heated at 80 °C with stirring for 3 hours. After the reaction was completed, the reaction mixture was diluted with deionized water and ethyl acetate. The organic layer was separated, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. Purification of the crude product by fast column chromatography (eluent: 20% ethyl acetate/hexane) afforded 2,6-dichloro-4-methoxybenzaldehyde as a white solid (210 mg, 87% yield). LCMS analysis of the product showed that the m/z of the [M-H]+ peak was 205, which was consistent with the calculated value of the molecular formula C8H7Cl2O2.
