To a suspension of 2-{[4-(2-hydroxyethyl)-1,3-thiazol-2-yl]thio}-2-methylpropionic acid resin (0.3 g) synthesized in Example 713-1 in tetrahydrofuran (3.0 mL) were added triphenylphosphine (0.12 g) and 4-phenylphenol (0.17 g), and the mixture was left standing for 15 min. Thereto was added diisopropyl azodicarboxylate (40% toluene solution, 0.26 ml), and the mixture was stirred at room temperature for 30 min. The resin was collected by filtration from the reaction mixture, and washed three times with tetrahydrofuran. This operation was repeated three times, and the obtained resin was washed three times each with dimethylformamide, tetrahydrofuran and methanol, and vacuum dried. To the resin was added trifluoroacetic acid, and the mixture was left standing at room temperature for 4 hr. The resin was filtered off and the filtrate was concentrated by blowing nitrogen gas thereto, and purified by HPLC to give the title compound (0.012 g) as a colorless oil.
