[CH3:1][O-].[Na+].[C:4]([O:8][C:9]([NH:11][C@H:12]1[CH2:17][CH2:16][C@H:15]([CH2:18][O:19]S(C)(=O)=O)[CH2:14][CH2:13]1)=[O:10])([CH3:7])([CH3:6])[CH3:5]>CO.C1COCC1>[C:4]([O:8][C:9](=[O:10])[NH:11][C@H:12]1[CH2:17][CH2:16][C@H:15]([CH2:18][O:19][CH3:1])[CH2:14][CH2:13]1)([CH3:7])([CH3:6])[CH3:5]A solution of sodium methoxide in methanol (6.0 mL of a 25% solution, ˜27.0 mmol) was added to a solution of trans methanesulfonic acid 4-tert-butoxycarbonylamino-cyclohexylmethyl ester (1.50 g, 4.88 mmol) in THF (15 mL) and methanol (15 mL). The mixture was heated at reflux for 6.75 hours. The cold mixture was concentrated under vacuum to remove most of the solvent then diluted with water (10 mL). The mixture was then cautiously neutralised with 1M hydrochloric acid then extracted with DCM (3×20 mL). The combined organic phase was dried over magnesium sulphate and concentrated under vacuum. The residue was purified by chromatography on silica gel (eluting with 9:1 cyclohexane:ethyl acetate) to afford 1.07 g (90%) of trans (4-methoxymethyl-cyclohexyl)-carbamic acid tert-butyl ester as a white solid. 1H NMR (400 MHz, CDCl3): δ 4.36 (br s, 1H), 3.37 (br s, 1H), 3.32 (s, 3H), 3.18 (d, 2H), 2.07-1.97 (m, 2H), 1.84-1.75 (m, 2H), 1.56-1.45 (m, 1H), 1.44 (s, 9H), 1.16-0.96 (m, 4H).
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