3,5-Bis(methoxymethoxy)-2-bromo-1-(2-methoxyethyl)-benzene (5.3 g, 16 mmol) obtained in Example 1, Step 4 was dissolved in tetrahydrofuran (0.10 L). After the solution was cooled to −78° C., a 1.6 mol/L solution of n-butyllithium in hexane (30 mL, 48 mmol) was added thereto, followed by stirring for 5 minutes. Benzaldehyde (6.4 mL, 62 mmol) was added to the reaction mixture, followed by stirring for 1 hour. To the reaction mixture was added a saturated aqueous solution of ammonium chloride (30 mL), and the mixture was extracted with ethyl acetate (0.30 L). 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=1/9-1/2) to obtain [2,4-bis(methoxymethoxy)-6-(2-methoxyethyl)phenyl]phenylmethanol (3.0 g, 53%). Then, [2,4-bis(methoxymethoxy)-6-(2-methoxyethyl)phenyl]phenylmethanol (3.0 g, 8.4 mmol) was dissolved in dichloromethane (50 mL), and Molecular Sieves 4 Å (7.9 g) and pyridinium dichromate (7.9 g, 21 mmol) were added thereto, followed by stirring at room temperature for 5 hours. The reaction mixture was filtered, and the filtrate was concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (ethyl acetate/hexane=1/9-1/2) to obtain 2,4-bis(methoxymethoxy)-6-(2-methoxyethyl)phenyl=phenyl=ketone (2.9 g, 96%).
