[C:1]([O:5][C:6](=[O:16])[NH:7][C@H:8]1[CH2:13][CH2:12][C@H:11]([CH2:14][OH:15])[CH2:10][CH2:9]1)([CH3:4])([CH3:3])[CH3:2].N1C=CC=CC=1.[CH3:23][S:24](Cl)(=[O:26])=[O:25]>C(Cl)Cl>[C:1]([O:5][C:6]([NH:7][C@H:8]1[CH2:9][CH2:10][C@H:11]([CH2:14][O:15][S:24]([CH3:23])(=[O:26])=[O:25])[CH2:12][CH2:13]1)=[O:16])([CH3:4])([CH3:2])[CH3:3]Trans (4-hydroxymethyl-cyclohexyl)-carbamic acid tert-butyl ester (3.49 g, 15.0 mmol) in DCM (50 mL) was treated with pyridine (4.98 mL, 60.8 mmol). The mixture was cooled to 0° C. and methanesulfonyl chloride (2.36 mL, 30.4 mmol) was added dropwise over 5 minutes. The mixture was stirred at room temperature for 5 hours. The mixture was then concentrated under vacuum. The residue was partitioned between ethyl acetate and water and the aqueous phase was extracted with ethyl acetate (×2). The combined organic extracts were washed with brine, dried with sodium sulfate and concentrated under vacuum. The residue was triturated with cyclohexane then dried under vacuum to give a white solid. Further purification by column chromatography on silica gel (eluting with 1:1 cyclohexane/ethyl acetate) gave 4.17 g (90%) of trans methanesulfonic acid 4-tert-butoxycarbonylamino-cyclohexylmethyl ester as a white solid. 1H NMR (400 MHz, CDCl3) δ: 4.37 (br s, 1H), 4.02 (d, 2H), 3.39 (br s, 1H), 3.00 (s, 3H), 2.11-2.00 (m, 2H), 1.91-1.81 (m, 2H), 1.77-1.64 (m, 1H), 1.43 (s, 9H), 1.18-1.05 (m, 4H).
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