To a solution of 4-[9-(N-t-butyloxycarbonylaminosulfonylamino)nonyl]-7-methoxymethoxy-3-(4-methoxymethoxyphenyl)-3-methylchroman (5 7 mg, 0.088 mmol) in dichloromethane (2 ml) were added 4,4,5,5,5-pentafluoropentyl alcohol (15.6 mg, 0.088 mmol) and triphenylphosphine (23 mg, 0.088 mmol) at room temperature. Diethyl azodicarboxylate in dichloromethane (1 ml) was added dropwise to the reaction mixture at the same temperature until the color of the reaction solution turned to yellow, which was then stirred overnight. After the reaction was completed, the organic solvent was evaporated under reduced pressure. The crude product thus obtained was subjected to preparative TLC (n-hexane:ethyl acetate=8:2) to give the title compound (47 mg, yield 67%) as a white solid.
