A solution of 2.46 M n-butyllithium in hexane (1.11 mL) was added to a solution of 2-methoxy-3-methyl-6-[4-(methylsulfanyl)benzyl]pyridine obtained in Reference Example 2-1 (400 mg) in tetrahydrofuran (5 mL) in the presence of an argon gas at −78° C., and the mixture was stirred at −35° C. for 30 minutes. The reaction solution was cooled again to −78° C. and a solution of cyclopentylmethyl 4-methylbenzenesulfonate (549 mg) in tetrahydrofuran (3 mL) was added, after which the mixture was stirred at −78° C. to 0° C. for two hours. The reaction solution was poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate and filtered. The solvent was then evaporated under reduced pressure. The residue was purified by preparative TLC (hexane:ethyl acetate=19:1) to give 6-{2-cyclopentyl-1-[4-(methylsulfanyl)phenyl]ethyl}-2-methoxy-3-methylpyridine as a colorless amorphous (220 mg, 42%).
