Br.[NH2:2][C@H:3]1[CH2:8][CH2:7][CH2:6][CH2:5][C@H:4]1[C:9]([O:11]CC)=O.Cl[C:15]([O:17][CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)=[O:16].[C:25](=O)([O-])[O-].[Na+].[Na+]>C(Cl)Cl>[CH2:18]([O:17][C:15](=[O:16])[NH:2][CH:3]1[CH2:8][CH2:7][CH2:6][CH2:5][CH:4]1[C:9](=[O:11])[CH3:25])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1To a 0° C. solution of ethyl cis-2-amino-1-cyclohexanecarboxylate HBr salt (22.34 g, 88.6 mmol) in 250 mL of methylene chloride, was added benzyl chloroformate (12.6 mL, 88.3 mmol) and 250 mL of an aqueous sodium carbonate solution. The reaction mixture was stirred for 24 h at ambient temperature. The organic layer was separated and washed with 250 mL of water, dried over sodium sulfate, filtered and concentrated to give a crude liquid. The product was purified by column chromatography (10-50:90-50 ethyl acetate/hexanes) to give 26.45 g of (2-acetyl-cyclohexyl)-carbamic acid benzyl ester as a clear liquid. Yield: 98%, MS: 306 (M+H+).
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