To diisopropylamine (0.21 mL, 1.52 mmol), a 2.69 M solution of n-butyl lithium in hexane (0.57 mL, 1.52 mmol) was added at −78° C. followed by stirring for 15 minutes. After adding anhydrous tetrahydrofuran (1.5 mL), the mixture was further stirred for 15 minutes at −78° C. Subsequently, a solution of methyl 3-{2-[(1R)-1-({(2R)-2-{[tert-butyl(dimethyl)silyl]oxy}-3-[(2S)-2-(3-fluoro-4-methylbenzyl)pyrrolidin-1-yl]propyl}oxy)ethyl]phenyl}-2-methylpropanoate (445 mg, 0.76 mmol), which had been obtained in Example 179 (179b), in tetrahydrofuran (1 mL) was added thereto and stirred at −78° C. for 1 hour. After adding methyl iodide (0.14 mL, 2.28 mmol), the mixture was stirred at room temperature for 17 hours. Upon the completion of the reaction, water was added. After extracting the mixture with ethyl acetate, the solvent was distilled off under reduced pressure. The residue was purified by silica gel chromatography (n-hexane/ethyl acetate=85/15) to give the title compound as a pale yellow oily substance (309 mg, yield 68%).
