1: 85 percent / pyridinium p-toluene sulfonate / aq. ethanol / 5 h / 53 - 58 °C 2: 98 percent / triethylamine / CH2Cl2 / 0.25 h 3: 65 percent / NaN3 / dimethylsulfoxide 4: triphenylphosphine, boiling stones / tetrahydrofuran; H2O / Ambient temperature 5: hydrogen / PtO2 / ethanol / Ambient temperature View Scheme