[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]1To a solution of tert-butyl 6-methyl-1,2,3-oxathiazinane-3-carboxylate 2-oxide (2.52 g, 10.7 mmol) in acetonitrile (25 mL) and water (15 mL) cooled to 0° C. is added sodium periodate (3.4 g, 16.1 mmol) in one portion. After 5 min, the pH is adjusted to 7-8 by addition of saturated Na2HPO4 solution. A solution of RuCl3 (22 mg, 0.11 mmol) in water (0.5 mL) is added and the pH is kept between 6 and 9 by addition of Na2HPO4 solution. After 2 h, water (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. Then the combined organic layers are dried (MgSO4), filtered and concentrated. The crude compound is purified by flash column chromatography to afford the title compound (1.63 g, 61%).
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