In 12 ml of methylene chloride were dissolved 107 mg of 4-[2-(S)-propoxypropanoyloxy]benzoic acid, 95 mg of 4-[(S)-2-methyl butoxycarbonyl]phenol, and 140 mg of dicyclohexylcarbodiimide, and a catalytic amount of 4-dimethylaminopyridine was added to the solution, followed by stirring at room temperature. After 5 hours, diethyl ether was added to the reaction mixture, and any insoluble matter was removed by filtration. The filtrate was washed successively with a 10% hydrochloric acid aqueous solution, a saturated sodium bicarbonate aqueous solution, water, and a saturated sodium chloride aqueous solution, and dried over sodium sulfate. The solvent was removed from the residue by distillation, and the resulting oily substance was purified by silica gel column chromatography to obtain 139 mg of the entitled compound as a transparent oily substance. This compound did not crystalize even when allowed to stand at room temperature or less for a long time. The structure of the compound was confirmed by NMR and IR spectra.
