4-(3-Chloropropyloxy)-5-methoxy-2-nitrobenzaldehyde (0.40 g, 1.5 mmol) was dissolved in toluene (6.0 mL) and the solution was added with potassium carbonate (1.0 g, 7.3 mmol) dissolved in morpholine (0.38 mL, 4.4 mmol), sodium iodide (0.44 g, 2.9 mmol), tetrabutylammonium bromide (24 mg, 0.007 mmol) and water (2.0 mL), followed by stirring at 100° C. for 19 hours. The reaction mixture was added with water and extracted with ethyl acetate. The organic layer was washed with water and saturated brine, dried over anhydrous magnesium sulfate and the solvent was evaporated under reduced pressure. The filtrate was purified by silica gel column chromatography (hexane/ethyl acetate=100/0 to 0/100) and concentrated to obtain 5-methoxy-4-[3-(morpholin-4-yl)propyloxy]-2-nitrobenzaldehyde (0.26 g, 54%).
