A solution of methyl (R)-7-(4-fluorophenyl)-7-[3-(1-hydroxyethyl)-6-methoxy-2,4,5-trimethylphenyl]heptanoate (4.1 g, 9.5 mmol) in dichloromethane (10 ml) was added to a solution of pyridinium chlorochromate (3.3 g, 15.2 mmol) in dichloromethane (20 ml) at room temperature. The mixture was stirred for 2 hours at the same temperature. To the mixture was added diethyl ether. Insolubles were filtered off, and the filtrate was concentrated under reduced pressure. The residue was subjected to a silica gel column chromatography to give methyl (R)-7-(3-acetyl-6-methoxy-2,4,5-trimethylphenyl)-7-(4-fluorophenyl)heptanoate (3.9 g). Physico-chemical properties and spectral data are shown in [Table 5].
