To a solution of tert-butyl (1S,2R)-1-benzyl-2-hydroxyhexylcarbamate (1.24 g, 4.03 mmol), triphenylphosphine (1.06 g, 4.03 mmol) in 40 mL THF was added hydrozoic acid HN3 (4 mL, 8.07 mmol, 2M in benzene) followed by dropwise addition of diethylazodicarboxylate (0.7 mL, 4.44 mmol) in 10 mL THF. The reaction mixture was stirred at room temperature for 8 h, combined with a previous 250 mg tert-butyl (1S,2R)-1-benzyl-2-hydroxyhexylcarbamate probe reaction, concentrated in vacuo, and purified by flash chromatography (120 g silica, 0−>50% EtOAc/hexanes) to afford tert-butyl (1S,2R)-1-benzyl-2-hydroxyhexylcarbamate and tert-butyl (1S,2S)-2-azido-1-benzylhexylcarbamate as a white solid. 1H NMR (400 MHz, CDCl3) δ 7.36-7.16 (m, 5H), 4.63 (d, J=10.1 Hz, 1H), 4.00-3.88 (m, 1H), 3.40-3.28 (m, 1H), 2.91 (A of ABX, dd, J=13.6, 6.8 Hz, 1H), 2.76 (B of ABX, dd, J=13.6, 9.1 Hz, 1H), 1.70-1.48 (m, 2H), 1.42-1.20 (m, 4H), 1.39 (s, 9H), 0.52 (t, J=7.1 Hz, 3H).
