a) Synthesis of 1,1-dimethylethyl 4-((benzyloxycarbonyl)amino)hexahydro-1H-azepane-1-carboxylate: 1,1-dimethylethyl 4-aminohexahydro-1H-azepane-1-carboxylate (2.85 g, 13.32 mmol) was dissolved in dichloromethane (50 mL) and benzyl chloroformate (2.30 mL, 15.98 mmol) was added. ) and triethylamine (5.3 mL, 40.0 mmol). The reaction mixture was stirred at room temperature for 4 hours. After completion of the reaction, the organic layer was washed with saturated sodium bicarbonate solution and brine, dried with magnesium sulfate, filtered and concentrated to obtain the crude product. Purification by column chromatography (30%-70% ethyl acetate/hexane) afforded tert-butyl 4-(((benzyloxy)carbonyl)amino)azepane-1-carboxylate as a white solid in 82% (3.8 g) yield.LCMS (M + H): 349.
