1: 4-(N,N-dimethlyamino)pyridine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / dichloromethane / 18 h / 0 - 20 °C / |Inert atmosphere 2: (1S)-10-camphorsulfonic acid / dichloromethane; methanol / 2.5 h / 0 °C 3: triethylamine; sulfur trioxide pyridine complex; dimethyl sulfoxide / dichloromethane / 1 h / 0 °C / |Inert atmosphere 4: lithium iodide; chromium dichloride / tetrahydrofuran / 3.33 h / 20 °C / |Inert atmosphere 5: trifluoroacetic acid / dichloromethane / 1.5 h / 0 °C View Scheme