1: 93 percent / 2percent aq. H2SO4 / methanol / Ambient temperature 2: 91 percent / NEt3, DMAP / CH2Cl2 3: NEt3, DMAP / CH2Cl2 / 0 °C 4: NaN3 / 18-crown-6 / dimethylformamide / 20 h / 75 °C 5: 87 percent / DDQ, H2O / CH2Cl2 / 2 h / 0 °C 6: 94 percent / Bu4NF*3H2O / tetrahydrofuran / 1 h View Scheme

<b>Multi-step reaction with 3 steps<br /> </b>1: Et₃N / tetrahydrofuran / 0.1 h / Heating<br />2: 2.76 g / MCPBA / CH₂Cl₂ / 24 h / 20 &deg;C<br />3: KHMDS / toluene; 1,2-dimethoxy-ethane / -55 - 20 &deg;C<br /> <br /> &nbsp;

<b>Multi-step reaction with 6 steps<br /> </b>1: 99 percent / p-TsOH / dimethylformamide / 5 h / 50 &deg;C / 10 Torr<br />2: 100 percent / NaBH₄, LiCl / 1) THF, 30 min, 2) EtOH, 24 h<br />3: 94 percent / BH₃*THF / tetrahydrofuran / 6 h / Heating<br />4: 89 percent / p-TsOH / tetrahydrofuran<br />5: 1) DMSO, (COCl)2, 2) NEt₃ / 1) -78 deg C, 2 h, 2) -78 deg C, 30 min<br />6: 1) PhLi / 1) toluene/Et₂O, 0 deg C, 20 min, 2) THF, -30 deg C, 1 h<br /> <br /> &nbsp;