Ethyl 6-{[2-({(3,5-bis-trifluoromethyl-benzyl)-[5-(2-methoxy-ethoxy)-pyrimidin-2-yl]-amino}-methyl)-4-trifluoromethyl-phenyl]-ethyl-amino}-hexanoate (113 mg) is dissolved in a mixed solvent of ethanol (2 ml) and tetrahydrofuran (1 ml), and thereto is added 1M-aqueous sodium hydroxide solution (1 ml), and the mixture is stirred at room temperature for 2 hours. The reaction solution is made weakly acidic with a 10% aqueous citric acid solution, and the mixture is extracted with ethyl acetate, and the organic layer is washed with a saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure. The resulting residue is purified by silica gel column chromatography (chloroform:methanol=1:0→49:1) to give 6-{[2-({(3,5-bis-trifluoromethyl-benzyl)-[5-(2-methoxy-ethoxy)-pyrimidin-2-yl]-amino}-methyl)-4-trifluoromethyl-phenyl]-ethyl-amino}-hexanoic acid (111 mg). MS (m/z): 711 [M+H]+
