The general procedure for the synthesis of 2-methoxy-5-fluoropyridine-4-carboxaldehyde from (5-fluoro-2-methoxypyridin-4-yl)methanol was as follows: (5-fluoro-2-methoxypyridin-4-yl)methanol (1.40 g, 8.91 mmol) was dissolved in dichloromethane (DCM, 50 mL) with stirring. A dichloromethane (DCM, 70 mL) solution of Dess-Martin periodontane (4.535 g, 10.69 mmol) was slowly added and the reaction mixture continued to be stirred for 1.5 hours at room temperature. After completion of the reaction, the organic layer was washed sequentially with 1 M aqueous sodium hydroxide solution (2 x 75 mL), water (75 mL) and brine, dried over anhydrous magnesium sulfate (MgSO?), filtered and concentrated to afford 2-methoxy-5-fluoropyridine-4-carbaldehyde as a yellow oil (0.481 g, 35% yield).1H NMR (399.902 MHz, CDCl?) δ 3.94 (s, 3H), 7.08-7.11 (m, 1H), 8.20-8.22 (m, 1H), 10.32 (s, 1H).
