11.25 g (34.8 mmol) of benzyl (4S)-4-((t-butoxycarbonyl)amino)-5-hydroxypentanoate acid obtained in step 1 was dissolved in 120 ml of dichloromethane. 9.7 ml (69.6 mmol) of triethylamine was added to the obtained solution. 6.0 ml (52.2 mmol) of mesyl chloride was added to the obtained mixture at 0° C., and they were stirred at room temperature for 4 hours. The solvent was evaporated, and the residue was treated with ethyl acetate as the extracting solvent by an ordinary method to obtain the crude product. This crude product was dissolved in 100 ml of N,N-dimethylformamide (dehydrated). 7.4 g (174 mmol) of lithium chloride was added to the obtained solution, and they were stirred at 50° C. for 6 hours. The solvent was evaporated, and the residue was treated with ethyl acetate as the extracting solvent by an ordinary method to obtain the crude product, which was dissolved in 150 ml of N,N-dimethylformamide (dehydrated). 6.8 g (27.7 mmol) of 3-hydroxy-4-iodobenzonitrile, 5.73 g (41.5 mmol) of potassium carbonate and 4.6 g (27.7 mmol) of potassium iodide were added to the obtained solution, and they were stirred at 90° C. overnight. The solvent was evaporated, and the residue was treated with ethyl acetate as the extracting solvent by an ordinary method to obtain the crude product, which was then purified by the silica gel column chromatography to obtain the title compound.
