Methanol (0.7 mL) and tetrahydrofuran (0.7 mL) were added to methyl 2,2-dimethyl-3-({4-methyl-6′-[4-(trifluoromethyl)-1-{[2-(trimethylsilyl)ethoxy]methyl}-1H-imidazol-2-yl]-3,3′-bipyridin-6-yl}oxy)propanoate (99 mg), and after adding 2N aqueous sodium hydroxide solution (0.7 mL) to the mixture, the resulting mixture was stirred at 50° C. for 2 hours. To the reaction mixture was added ethyl acetate, and the mixture was neutralized by 2N hydrochloric acid. The organic layer was separated, washed with a saturated brine, and the residue obtained by concentrating the mixture under reduced pressure was purified by silica gel column chromatography (n-hexane:ethyl acetate=76:24 to 0:100) to obtain 2,2-dimethyl-3-({4-methyl-6′-[4-(trifluoromethyl)-1-{[2-(trimethylsilyl)ethoxy]methyl}-1H-imidazol-2-yl]-3,3′-bipyridin-6-yl}oxy)propanoic acid (81 mg).
