1: 86 percent / pyridine*SO3, Et3N / dimethylsulfoxide / 0.17 h 2: 91 percent / CH2Cl2 / 16 h 3: 99 percent / DIBAL-H / toluene / 0.5 h / -78 °C 4: 76 percent / MnO2 / CH2Cl2 / 24 h 5: 97 percent / n-BuLi / tetrahydrofuran; hexane / 1.) -78 deg C, 10 min; 2.) from -78 deg C to r.t. 6: 84 percent / CSA / methanol / 16 h / Ambient temperature View Scheme

1: 34 percent / CSA / CH2Cl2 / 4 h 2: 86 percent / pyridine*SO3, Et3N / dimethylsulfoxide / 0.17 h 3: 91 percent / CH2Cl2 / 16 h 4: 99 percent / DIBAL-H / toluene / 0.5 h / -78 °C 5: 76 percent / MnO2 / CH2Cl2 / 24 h 6: 97 percent / n-BuLi / tetrahydrofuran; hexane / 1.) -78 deg C, 10 min; 2.) from -78 deg C to r.t. 7: 84 percent / CSA / methanol / 16 h / Ambient temperature View Scheme

1: diisobutylaluminum hydride (DIBAL) / toluene / -78 °C 2: H+ / CH2Cl2 / Ambient temperature 3: CH2Cl2 / Ambient temperature 4: diisobutylaluminum hydride (DIBAL) / toluene / -78 °C 5: MnO2 / CH2Cl2 6: tetrahydrofuran 7: MeOH, H+ View Scheme

1: H+ / CH2Cl2 / Ambient temperature 2: CH2Cl2 / Ambient temperature 3: diisobutylaluminum hydride (DIBAL) / toluene / -78 °C 4: MnO2 / CH2Cl2 5: tetrahydrofuran 6: MeOH, H+ View Scheme

Yield given. Multistep reaction;