1: 94 percent / N,N-diisopropylethylamine / dioxane 2: 74 percent / CBr4, PPh3 / CH2Cl2 / 18 h 3: NaN3 / dimethylformamide / 55 °C 4: 83 percent / H2 / 10percent Pd/C / H2O; ethanol / 5171.5 Torr View Scheme