To a stirred solution of 3-methoxymethoxypyridine-4-carboxaldehyde (11.0 g, 65.83 mmol) in tetrahydrofuran (THF, 50 mL) was added 3 N hydrochloric acid (HCl, 100 mL) and the reaction mixture was stirred for 1 h at 60 °C. The reaction was carried out in an ice bath. Upon completion of the reaction, the mixture was cooled in an ice bath and the pH was adjusted with solid potassium carbonate (K2CO3) to 7. Subsequently, the mixture was extracted with ethyl acetate (EtOAc, 5 × 250 mL). The organic layers were combined, dried over anhydrous sodium sulfate (Na2SO4) and concentrated under reduced pressure to give the crude product. The crude product was purified by silica gel column chromatography (100-200 mesh) with 23% ethyl acetate/hexane as eluent to give 3-hydroxypyridine-4-carboxaldehyde (4.0 g, 32.496 mmol, 49.4% yield) as a light yellow solid. The product was analyzed by GC-MS showing a molecular ion peak of 123 (m/z), and the 1H-NMR (DMSO-d6, 400 MHz) data were as follows: δ 11.04 (broad single peak, 1H), 10.37 (single peak, 1H), 8.46 (single peak, 1H), 8.20 (double peak, 1H, J = 4.88 Hz), and 7.46 (double peak, 1H, J = 4.88 Hz).The purity of GC-FID analysis was 99.51%.
