1: 91 percent / DIBALH, BF3*Et2O / CH2Cl2 / 3 h / -78 °C 2: NaCNBH3 / acetic acid / 0.5 h / 10 °C 3: 37 mg / NaOMe / methanol; tetrahydrofuran / 2 h / Ambient temperature 4: 71 percent / DIBALH / CH2Cl2 / 0.5 h / -90 °C 5: 65 percent / Ac2O, NaOAc / acetic acid View Scheme