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

<b>Multi-step reaction with 2 steps<br /> </b>1: BF₃*Et₂O / CH₂Cl₂ / 3.5 h<br />2: 57 mg / DBU / CH₂Cl₂ / 1 h / Ambient temperature<br /> <br /> &nbsp;

<b>Multi-step reaction with 5 steps<br /> </b>1: 3.54 g / NaI, m-CPBA / tetrahydrofuran / 0.33 h / Ambient temperature<br />2: Bu₃SnH, AIBN / benzene / 1 h / Heating<br />3: 84 percent / TFA / benzene / 0.33 h<br />4: BF₃*Et₂O / CH₂Cl₂ / 3.5 h<br />5: 57 mg / DBU / CH₂Cl₂ / 1 h / Ambient temperature<br /> <br /> &nbsp;

<b>Multi-step reaction with 7 steps<br /> </b>1: CuI / tetrahydrofuran / -78 &deg;C<br />2: Et₃N / tetrahydrofuran / -78 - 20 &deg;C<br />3: 3.54 g / NaI, m-CPBA / tetrahydrofuran / 0.33 h / Ambient temperature<br />4: Bu₃SnH, AIBN / benzene / 1 h / Heating<br />5: 84 percent / TFA / benzene / 0.33 h<br />6: BF₃*Et₂O / CH₂Cl₂ / 3.5 h<br />7: 57 mg / DBU / CH₂Cl₂ / 1 h / Ambient temperature<br /> <br /> &nbsp;

<b>Multi-step reaction with 3 steps<br /> </b>1: 84 percent / TFA / benzene / 0.33 h<br />2: BF₃*Et₂O / CH₂Cl₂ / 3.5 h<br />3: 57 mg / DBU / CH₂Cl₂ / 1 h / Ambient temperature<br /> <br /> &nbsp;