In ethanol (5 ml) was dissolved 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-[3-[N-methyl-N-[2-(3,4-methylenedioxyphenoxy)ethyl]amino]propyl]-5-ethoxycarbonylmethyl-1,3thiazolidin-4-one (100 mg) prepared in Example 46, and a solution of sodium hydroxide (200 mg) in 20% water-containing ethanol was added, then the mixture was stirred at room temperature overnight. After completion of the reaction, the mixture was neutralized with 1N hydrochloric acid and concentrated under reduced pressure. To the residue was added a mixture of water (50 ml) and chloroform (50 ml), and the mixture was stirred. The organic layer was separated, washed with brine, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, and the residue was triturated with n-hexane to afford 80 mg (84%) of the title compound as a pale yellow solid. NMR (CDCl3) (200 MHz) δ: 1.41 (18/2H, s), 1.42 (18/2H, s), 1.4-2.4 (2H, m), 2.85 (3/2H, s), 2.90 (3/2H, s), 2.7-3.8 (8H, m), 4.1-4.7 (3H, m), 5.2-5.4 (1H, m), 5.66 (1/2H, brs), 5.81 (1/2H, brs), 5.89 (2H, s), 6.2-6.7 (3H, m), 7.13 (2/2H, s), 7.14 (2/2H, s)
