To a solution of 725 mg (1.63 mmol) of (3S,5R,6S)-3-allyl-5-(3-chlorophenyl)-6-(4-chlorophenyl)-3-methyl-1-(pentan-3-yl)piperidin-2-one (Example 3, Step A) in a mixture of acetonitrile (4 mL), carbon tetrachloride (4 mL) and water (5.9 mL) added 1.40 g (6.53 mmol) of sodium periodate followed by 44 mg (0.20 mmol) of ruthenium(III) chloride hydrate. The dark brown biphasic mixture was stirred vigorously at room temperature for 21 h, and then was acidified with 1 N HCl. The mixture was diluted with EtOAc and filtered through a pad of Celite® (J. T. Baker, Phillipsberg, N.J., diatomaceous earth). After filtration, the layers were separated and the aqueous layer was extracted with EtOAc (1×). The combined organic layers were washed with saturated aqueous sodium chloride (1×), then were dried over Na2SO4, filtered and the filtrate was concentrated. Purification of the residue by flash chromatography on silica gel (0 to 25% MeOH/DCM, gradient elution) provided the title compound as a white solid.
