To a solution of (3S,5R)-benzyl 3-(benzoyloxy)-5-hydroxypiperidine-1-carboxylate (1 eq) in 20 mL of dichloromethane was added triethyl amine (3 eq) and methanesulfonyl chloride (1.5 eq) at 0° C. The reaction mixture was allowed to stir at room temperature for 2 hours. The crude mixture was diluted with 120 mL of EtOAc, washed with sat. aq. sodium bicarbonate, brine, then dried over anhydrous MgSO4, filtered, and concentrated in vacuo. The crude residue was dissolved in 25 mL of NMP. Sodium azide (2.2 eq) was added and the resulting suspension was stirred at 80° C. overnight. The reaction mixture was diluted with 200 mL of EtOAc and 100 mL of hexanes, washed with water, brine, then dried over anhydrous MgSO4, filtered, and concentrated in vacuo. The crude residue was purified by flash chromatography (EtOAc:hexanes=1:2) to yield (3S,5S)-benzyl 3-azido-5-(benzoyloxy)piperidine-1-carboxylate (88%). LC/MS (m/z): 381.0 (MH+). HPLC: Rt: 4.41 min.
