[CH3:1][O:2][C:3](=[O:20])[CH:4]([C:12]1[CH:17]=[CH:16][C:15]([Cl:18])=[C:14]([Cl:19])[CH:13]=1)[CH2:5][CH:6]1[CH2:10][CH2:9][CH:8]([OH:11])[CH2:7]1.C[N+]1([O-])CCOCC1.C([N+](CCC)(CCC)CCC)CC>C(Cl)Cl>[CH3:1][O:2][C:3](=[O:20])[CH:4]([C:12]1[CH:17]=[CH:16][C:15]([Cl:18])=[C:14]([Cl:19])[CH:13]=1)[CH2:5][CH:6]1[CH2:10][CH2:9][C:8](=[O:11])[CH2:7]1A mixture of 2-(3,4-dichloro-phenyl)-3-(3-hydroxy-cyclopentyl)-propionic acid methyl ester (prepared as in Example 36, 356.4 mg, 1.12 mmol), N-methylmorpholine N-oxide (197 mg, 1.68 mmol), and powdered molecular sieves (1.12 g) in methylene chloride (2.25 mL) at 25° C. was treated with tetrapropylammonium perrhuthenate (20 mg, 0.05 mmol). The resulting mixture was stirred at 25° C. for 30 min. At this time, the reaction was filtered through a pad of celite (ethyl acetate as eluent). The filtrate was concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 75/25 hexanes/ethyl acetate) afforded 2-(3,4-dichloro-phenyl)-3-(3-oxo-cyclopentyl)-propionic acid methyl ester (261.3 mg, 73.8%) as a clear oil: EI-HRMS m/e calcd for C15H16Cl2O3 (M+Na)+ 337.0370. found 337.0371.
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