1: triphenylphosphine; diethyl azodicarboxylate / benzene / 4.25 h / 20 °C 2: 697 mg / NH4OH / methanol; H2O / 1.5 h / 20 °C 3: 87 percent / N-ethyldiisopropylamine / CH2Cl2 / 66 h / 20 °C 4: 100 percent / Bu4NF / tetrahydrofuran / 1 h / 20 °C 5: 92 percent / 4-(dimethylamino)pyridine; camphorsulfonic acid; dicyclohexylcarbodiimide / CH2Cl2 / 18.5 h / 20 °C 6: 83 percent / CF3CO2H / tetrahydrofuran; H2O / 22 h / 20 °C 7: 96 percent / 4-(dimethylamino)pyridine; camphorsulfonic acid; dicyclohexylcarbodiimide / CH2Cl2 / 14 h / 20 °C 8: 19 percent / CH3CO2H / propan-2-ol; H2O 9: triethylamine / toluene / 1 h / 20 °C 10: triethylamine; 4-(dimethylamino)pyridine / toluene / 3.5 h / 80 °C 11: 90 percent / trifluoroacetic acid / CH2Cl2 / 7.5 h / 20 °C View Scheme