1: DIBAL-H / toluene / -78 °C 2: pyridine / tetrahydrofuran / 25 °C 3: SnCl4 / CH2Cl2 / 1) 25 deg C, 1 h, 2) -78 deg C up to 25 deg C 4: 1) NaIO4, 2) pyridine / THF, H2O, 1) 25 deg C, 2) toluene, reflux 5: 90 percent / (Bu)4NF / tetrahydrofuran / 25 °C View Scheme