1: water; AD-mix-α / tert-butyl alcohol / 4 °C 2: nitric acid; sulfuric acid / dichloromethane; water / 0.5 h / -78 °C 3: sodium hydroxide; water / ethanol / 2 h / 0 °C 4: 4-(N,N-dimethlyamino)pyridine; 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / 5 h / 0 - 20 °C View Scheme