1: sodium dithionite; ammonium hydroxide / water / 95 °C 2: 1-ethyl-(3-(3-dimethylamino)propyl)-carbodiimide hydrochloride / 1H-imidazole; 4-(N,N-dimethlyamino)pyridine / DMF (N,N-dimethyl-formamide) / 12 h / 20 °C 3: sodium hydroxide / methanol; water / 50 °C View Scheme