Methyl morpholine oxide → (-)-N-[[(5S)-3-(3,4-dihydro-2,2-dioxido-1H-2-benzothiopyran-6-yl)-2-oxo-5-oxazolidinyl]methyl]acetamide

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Reaction Steps

A solution of (−)-N-[[(5S)-3-(3,4-dihydro-1H-2-benzothiopyran-6-yl)-2-oxo-5-oxazolidinyl]methyl]acetamide (Example 10, 545 mg, 1.78 mmol) in acetone/H2O (3/1, 36 mL) under N2 is treated with N-methylmorpholine N-oxide (521 mg, 4.45 mmol) and OsO4 (2.5 wt % in tBuOH, 1.11 mL, 5 mol %), and the resulting mixture is stirred at ambient temperature for 18 hrs and is then cooled in an ice bath and treated with half-saturated aqueous NaHSO3 (50 mL). The mixture is extracted with CH2Cl2 (3×75 mL), and the combined organic phase is washed with brine (20 mL), dried over anhydrous Na2SO4 and concentrated under reduced pressure to give the crude product which is then chromatographed on a Flash 40S silica gel (40 g, 32-63 μm) cartridge, eluting with a gradient of MeOH/CH2Cl2 (1/99-4/96). Those fractions with an Rf=0.39 by TLC (MeOH/CHCl3, 10/90) are pooled and concentrated and the product triturated with CH2Cl2/Et2O to give 517 mg (86%) of the title compound as a white solid, mp 177-178° C. MS (ESI+) for C15H18N2O5S m/z 339 (M+H)+; [α]25D=−23° (c 0.97, DMSO).

Provenance & Evidence