[C:1]([O:5][C:6](=[O:16])[NH:7][C@H:8]1[CH2:13][CH2:12][C@H:11](SC)[CH2:10][CH2:9]1)([CH3:4])([CH3:3])[CH3:2].O[O:18][S:19]([O-:21])=O.[K+].[CH3:23]O>O.C(OCC)(=O)C>[C:1]([O:5][C:6](=[O:16])[NH:7][C@H:8]1[CH2:9][CH2:10][C@H:11]([S:19]([CH3:23])(=[O:21])=[O:18])[CH2:12][CH2:13]1)([CH3:4])([CH3:2])[CH3:3]A solution of trans (4-methylsulfanyl-cyclohexyl)-carbamic acid tert-butyl ester (0.51 g, 2.10 mmol) in methanol (7 mL) was cooled to 0° C. and treated with a suspension of oxone (1.28 g, 4.20 mmol) in water (3.1 mL). The mixture was stirred at ambient temperature for 20 minutes, then diluted with ethyl acetate and water. The phases were separated and the aqueous phase was extracted with ethyl acetate (×2). The combined organic extracts were washed with 10% aqueous citric acid solution, saturated sodium hydrogen carbonate solution, and brine, dried with sodium sulphate and concentrated under vacuum to give 412 mg (71%) of trans (4-methanesulfonyl-cyclohexyl)-carbamic acid tert-butyl ester as a white solid which was used without further purification. 1H NMR (400 MHz, CDCl3) δ: 4.39 (br s, 1H), 3.43 (br s, 1H), 2.83 (s, 3H), 2.78 (m, 1H), 2.25 (m, 4H), 1.67 (m, 2H), 1.44 (s, 9H), 1.28-1.12 (m, 2H).
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