By customary procedures, 3-chloro-4-hydroxybenzoic acid was reacted with dodecylbromide in a mixed solution of ethanol and water containing sodium hydroxide to produce 3-chloro-4-dodecyloxybenzoic acid, and this acid was reacted with thionyl chloride to obtain 3-chloro-4-dodecyloxybenzoic acid chloride. Separately, 100 mg of (2S,5R)-2-hydroxy-5-hexyl-δ-valerolactone and 200 mg of 4-benzyloxybenzoic acid were dissolved in 200 ml of benzene, 190 mg of diethyl azodicarboxylate and 250 mg of triphenylphosphine were added to the solution, and a reaction was carried out at room temperature with stirring overnight. The reaction mixture was concentrated under a reduced pressure, and the concentrate was separated and purified by the silica gel column chromatography to obtain 120 mg of 2-(4'-benzyloxybenzoyloxy)-5-hexyl-δ-valerolactone. This compound was catalytically reduced under a hydrogen pressure of 2 kg/cm2 by using Pd/C as the catalyst to obtain 2-(4'-hydroxy-benzoyloxy)-5-hexyl-δ-valerolactone. The obtained compound was dissolved in 20 ml of benzene, and 200 mg of 3-chloro-4-dodecyloxybenzoic acid chloride described above, 200 mg of triethylamine and 20 mg of N,N-dimethylaminopyridine were added to the solution, and a reaction was carried out with stirring overnight. The reaction liquid was treated by customary procedures and the intended product was separated and purified by the silica gel column chromatography. Recrystallization from ethanol gave 80 mg of (2R,5S)-2-[4-(3'-chloro-4'-dodecyloxybenzoyloxy)-benzoyloxy]-5-hexyl-δ-valeerolactone ##STR127##
