1: hydrazine acetate / dimethylformamide / 2 h / 25 °C 2: 2.49 g / DBU / CH2Cl2 / 2 h / 20 °C 3: HBr / acetic acid / 1 h / 20 °C 4: 74 percent / 4 Angstroem molecular sieves / AgOTf / CH2Cl2 / 36 h / 20 °C 5: Et3N; MeSiCl3 / tetrahydrofuran / 24 h / 60 °C 6: 44 mg / H2O / tetrahydrofuran / 0.5 h 7: pyridine / 2 h / 20 °C View Scheme

1: hydrazine acetate / dimethylformamide / 2 h / 25 °C 2: 2.49 g / DBU / CH2Cl2 / 2 h / 20 °C 3: HBr / acetic acid / 1 h / 20 °C 4: 75 percent / 4 Angstroem molecular sieves / AgOTf / CH2Cl2 / 36 h / 20 °C 5: Et3N; MeSiCl3 / tetrahydrofuran / 24 h / 60 °C 6: 31 mg / H2O / tetrahydrofuran / 0.5 h 7: 100 percent / pyridine / 2 h / 20 °C View Scheme