Methyl (±)-4-[α-hydroxy-5-(1-imidazolyl)-2-methylbenzyl]-3,5-dimethylbenzoate (35 g) was suspended in dichloroethane (350 ml) and pyridine (12 ml) and a solution of (S)-2-(4-methylbenzenesulfonylamino)propionyl chloride (31.4 g) in dichloroethane (70 ml) was added dropwise to the suspension over 10 minutes with stirring under ice-cooling. The mixture was stirred at room temperature for 4 hours, and the reaction mixture was washed successively with water, 5% citric acid, 5% potassium carbonate and water. The organic layer was separated and dried over magnesium sulfate. The solvent was evaporated under reduced pressure to give 58 g of methyl (±)-4-[5-(1-imidazolyl)-2-methyl-α-{(S)-2-(4-methylbenzenesulfonylamino)propionyloxy}benzyl]-3,5-dimethylbenzoate as a pale-yellow oil. This was crystallized from ethyl acetate (120 ml) and isopropyl ether (480 ml), and the obtained crystals were recrystallized from ethyl acetate (50 ml) and isopropyl ether (100 ml) to give 20 g of methyl (S)-4-[5-(1-imidazolyl)-2-methyl-α-{(S)-2-(4-methylbenzenesulfonylamino)propionyloxy}benzyl]-3,5-dimethylbenzoate as white crystals, melting point 103-105° C.
