A suspension of the 6-methoxy-2-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzaldehyde produced in Example 4-1 (1.01 g, 3.66 mmol), methyl 6-bromopyridine-2-carboxylate (0.79 g, 3.66 mmol), sodium carbonate (1.16 g, 11.0 mmol), and tetrakis(triphenylphosphine)palladium(0) (0.21 g, 0.18 mmol) in 1,2-dimethoxyethane (20.2 ml) and water (8.8 ml) was prepared at room temperature, and the suspension thus prepared was then stirred at 90° C. for 7 hours. After air-cooling, an aqueous solution of ammonium chloride was added to the reaction solution, and the mixed solution was then extracted with dichloromethane 21 times. The organic layer thus obtained was dried over anhydrous sodium sulfate. The solvent was distilled away under reduced pressure, and the residue thus obtained was then dissolved in DMF (20.2 ml). Thereafter, potassium carbonate (1.21 g, 8.78 mmol) and methyl iodide (0.27 ml, 4.39 mmol) were added to the resulting solution, and the mixture thus obtained was then stirred at 40° C. for 4 hours. After air-cooling, water was added to the reaction solution, and the mixed solution was then extracted with ethyl acetate. The organic layer thus obtained was washed with water, and was then dried over anhydrous sodium sulfate. The solvent was distilled away under reduced pressure, and the residue thus obtained was then purified by silica gel column chromatography (ethyl acetate:hexane=40:60, v/v) to obtain the title compound (0.625 g, yield: 60%).
