A solution of 280 mg of 1-bromo-4-phenylbutane in 5 ml of N,N-dimethylformamide was added to a mixture of 540 mg of N-[2-(p-hydroxyphenyl)ethyl]-3-tert-butoxycarbonyl-2(3-pyridyl)thiazolidine-4-carboxamide, 180 mg of potassium carbonate and 10 ml of N,N-dimethylformamide at room temperature. The mixture was stirred at 80° C. for 3 days. After cooling, 20 ml of water was added to the reaction mixture, and the organic matter was extracted with ethyl acetate. The organic layer was washed in sequence with water and saturated aqueous solution of sodium chloride, and dried over anhydrous sodium sulfate and concentrated under reduced pressure. Purification of the residue by silica gel column chromatography (eluent: hexane-ethyl acetate=1:3) gave 360 mg of N-[2-[p-(4-phenylbutoxy)phenyl]ethyl]-3-tert-butoxycarbonyl-2-(3-pyridyl)thiazolidine-4-carboxamide. Trifluoroacetic acid (5 ml) was added to the compound obtained, and the mixture was stirred at room temperature for 1.5 hour. The reaction mixture was concentrated under reduced pressure, the residue was dissolved in ethyl acetate, and the solution was washed in sequence with saturated aqueous solution of sodium hydrogen carbonate and saturated aqueous solution of sodium chloride, and dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (eluent: ethyl acetate) to give 230 mg of N-[2-[p-(4-penylbutoxy)phenyl]ethyl]-2-(3-pyridyl)-thiazolidine-4-carboxamide. This compound was dissolved in ethyl acetate, and 1 ml of 2N hydrogen chloride solution in dioxane was added. The resultant solid was collected by filtration, washed with ethyl acetate and dried to give 130 mg of N-[2-[p-(4-phenylbutoxy)phenyl]ethyl]-2-(3-pyridyl) thiazolidine-4-carboxamide dihydrochloride. Melting point 102° C.
