[OH:1][C:2]1[CH:3]=[C:4]([C:9]2([S:15][CH3:16])[CH2:14][CH2:13][O:12][CH2:11][CH2:10]2)[CH:5]=[C:6]([F:8])[CH:7]=1.C[OH:18].O>>[OH:1][C:2]1[CH:3]=[C:4]([C:9]2([S:15]([CH3:16])=[O:18])[CH2:14][CH2:13][O:12][CH2:11][CH2:10]2)[CH:5]=[C:6]([F:8])[CH:7]=1To a stirred solution of 4-(3-hydroxy-5-fluorophenyl)-4-methylthio-3,4,5,6-tetrahydro-2H-pyran (749 mg, 3.1 mmol)(EP 462830 A2 (1991)) in methanol-water (1:1.v/v; 20 ml) cooled to 0° C. was added NalO4 (710 mg, 3.3 mmol), the ice bath removed and the mixture stirred at room temperature for 2 hours. The reaction mixture was poured into water (50 ml) and extracted with ethyl acetate (50 ml). The organic extract was washed with water (50 ml), brine (50 ml), dried (MgSO4) and concentrated in vacuo. The residual solids were purified by column chromatography on silica gel (SiO2, 150 g; ethyl acetate) to afford 752 mg (94%) of the titled compound as white solids.
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