Methyl 3,5-bis(methoxymethoxy)-2-bromophenylacetate (15.0 g, 43.0 mmol) obtained in Example 3, Step 1 was dissolved in a mixed solvent of 1,2-dimethoxymethane (0.15 L) and water (6.0 mL). To the solution were added phenylboric acid (7.3 g, 60 mmol), bis(tri-o-tolylphosphine)palladium (II) dichloride (0.68 g, 0.86 mmol) and cesium carbonate (42 g, 0.13 mol) in an atmosphere of argon, followed by stirring for 16.5 hours under heating and reflux. After cooling to room temperature, the reaction mixture was filtered under reduced pressure, and the filtrate was concentrated under reduced pressure. To the resulting residue was added water (0.50 L), followed by extraction with ethyl acetate (0.40 L×2). The organic layer was dried over anhydrous sodium sulfate and then concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (ethyl acetate/hexane=1/4-1/3) to obtain a quantitative yield of methyl 3,5-bis(methoxymethoxy)-2-phenylphenylacetate.
