1: 17 percent / 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine / tetrahydrofuran / 20 h / 20 °C 2: 93.4 percent / 2 N NaOH / methanol / 1.5 h / 20 °C 3: 34.6 percent / diethyl azodicarboxylate; triphenylphosphine / dioxane / 10 h / 20 °C 4: 82.5 percent / NH3 / methanol / 20 h / 80 - 90 °C 5: 86 percent / aq. CF3CO2H / 3 h / 50 °C View Scheme