3-Benzyl-3,8-diazabicyclo[3.2.1]octane (13.5 g, 66.7 mmol) was used as starting material and mixed with triethylamine (6.75 g, 66.7 mmol) and di-tert-butyl dicarbonate (14.56 g, 66.7 mmol) in dichloromethane (100 ml). The reaction mixture was stirred under cooling in an ice bath for 3 hours. After completion of the reaction, the crude product was washed with water (150 ml) and the aqueous phase was then extracted with dichloromethane (50 ml). The organic phases were combined, dried over anhydrous sodium sulfate and concentrated under reduced pressure to give tert-butyl 3-benzyl-3,8-diazabicyclo[3.2.1]octane-8-carboxylate (13 g, 65% yield). The melting point of the product was 58-60°C.
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