[CH3:1][CH:2]1[O:7][S:6](=[O:8])[N:5]([C:9]([O:11][C:12]([CH3:15])([CH3:14])[CH3:13])=[O:10])[CH2:4][CH2:3]1.I([O-])(=O)(=O)=[O:17].[Na+].Cl>C(#N)C.O>[CH3:1][CH:2]1[O:7][S:6](=[O:17])(=[O:8])[N:5]([C:9]([O:11][C:12]([CH3:14])([CH3:13])[CH3:15])=[O:10])[CH2:4][CH2:3]1The crude tert-butyl 6-methyl-1,2,3-oxathiazinane-3-carboxylate 2-oxide (2.52 g, 10.7 mmol) is dissolved in acetonitrile (25 mL) and H2O (15 mL) is added. The solution is cooled in an ice bath and sodium periodate (3.4 g, 16.1 mmol) is added in one portion. After 5 min, the pH is adjusted to 7-8 by addition of saturated Na2HPO4 solution. Then RuCl3 (22 mg, 0.11 mmol) in H2O (0.5 mL) is added. The pH is kept between 6 and 9 by addition of Na2HPO4 solution. After 2 h, H2O (100 mL) is added and pH is adjusted to 6 by addition of 2M HCl solution. The reaction mixture is extracted with EtOAc and the organic layer is washed with NaHCO3 and brine and the washes are back extracted once with EtOAc. The combined organic layers are dried (MgSO4), filtered and concentrated. The crude product is purified via by flash column chromatography using a gradient elution of 5-80% ethyl acetate/hexanes which affords the title compound (1.63 g, 61%).
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