1: 81.2 percent / imidazole / dimethylformamide / 20 h / Ambient temperature 2: 99.2 percent / H2 / Pd/C / 1,2-dimethoxy-ethane / 8 h / 760 Torr / Ambient temperature 3: 76.2 percent / Et3N / CH2Cl2 / 15 h / Ambient temperature 4: 46.9 percent / DBU / dimethylsulfoxide / 35 h / 80 °C 5: 60 mg / aq. HF-urea / tetrahydrofuran / 15 h / Ambient temperature View Scheme