509143-03-7

149423-70-1

Step B: Synthesis of cis-(4-amino-cyclohexyl)-carbamic acid benzyl ester. To a solution of cis-(4-tert-butoxycarbonylamino-cyclohexyl)-carbamic acid benzyl ester (6.2 g, 0.018 mol) in dichloromethane (40 mL) was added trifluoroacetic acid (2.7 mL, 0.36 mol). The reaction mixture was stirred at room temperature for 4 hours. Upon completion of the reaction, the excess solvent was removed by rotary evaporation and the resulting oil was dissolved in dichloromethane (30 mL). The organic layer was extracted with dilute aqueous sodium hydroxide/aqueous sodium bicarbonate solution (30 mL). The aqueous layer was back-extracted twice with dichloromethane, and the organic layers were combined, dried over anhydrous magnesium sulfate, and concentrated to give cis-(4-amino-cyclohexyl)-carbamic acid benzyl ester (4.3 g, 97%) as a colorless oil. The product was used directly in the next reaction without further purification.ESI MS m/z 249.2 [M + H]+.