1.19 g (2.52 mmol) of ethyl 6-(3,5-difluoro-4-triisopropylsilanyloxybenzyl)-7-hydroxyheptanoate are stirred with 5 g of 4 Å molecular sieves and 442 mg (3.78 mmol) of N-methylmorpholine N-oxide in 50 ml of dichloromethane at room temperature for 10 minutes. 44 mg (0.13 mmol) of tetrapropylammonium perruthenate are added, and the mixture is stirred at room temperature until reaction is complete. The mixture is filtered and the filtrate is washed with water and saturated sodium chloride solution. The organic phase is dried over sodium sulfate and concentrated. The resulting crude product is purified by chromatography on silica gel (mobile phase: cyclohexane/ethyl acetate 3:1). 1.0 g (84% of theory) of the title compound is obtained.
