1: 84 percent / TFA / benzene / 0.33 h 2: BF3*Et2O / CH2Cl2 / 3.5 h 3: 57 mg / DBU / CH2Cl2 / 1 h / Ambient temperature 4: 1.) BH3*Me2S, 2.) H2O2, NaOH / 1.) THF, rt, 4.5 h, 2.) THF, H2O, rt, 12 h 5: CH2Cl2; triethylamine / 1.5 h / Ambient temperature 6: 80 percent / NaN3, 18-crown-6 / dimethylformamide / 1.5 h / 100 °C 7: 94 percent / CrO3, H2SO4 / H2O; acetone / 1.5 h / Ambient temperature 8: 1.) PPh3, 2.) NaBH3CN / 1.) THF, rt, 12 h, 2.) MeOH, AcOH, 12 h 9: 42 percent / H2O; formic acid / 12 h / 120 °C View Scheme