1: NaN3 / dimethylformamide / 3 h / 80 °C 2: Lindlar catalyst, H2 / ethyl acetate / 6 h / 30 °C / 2327.2 Torr 3: 1.) 1-hydroxybenzotriazole hydrate, N,N'-dicyclohexylcarbodiimide / 1.) EtOAc, RT, 2 h, 2.) 18 h 4: 89 percent / H2 / Pearlman's catalyst / ethanol / 18 h / 25 °C / 2327.2 Torr 5: 80 percent / ethyl acetate / 24 h / Ambient temperature View Scheme