To a solution of 2,3,5-trimethylphenol (0.80 g, 5.9 mmol), methyl (S)-7-(4-fluorophenyl)-7-hydroxyheptanoate (0.30 g, 1.2 mmol) and triphenylphosphine (0.46 g, 1.8 mmol) in 1,2-dichloroethane (20 ml) was added at 10° C. a solution of 95% DEAD (0.54 ml) in 1,2-dichloroethane (5 ml) taking 30 minutes. The mixture was stirred for one hour at the same temperature range, then the solvent was distilled off under reduced pressure. The residue was subjected to a silica gel column chromatography to give 0.15 g of methyl (R)-7-(4-fluorophenyl)-7-(2-hydroxy-3,4,6-trimethylphenyl)heptanoate.
