1: 80 percent / Swern oxidation 2: 88 percent / diisobutylaluminum hydride / diethyl ether / -60 °C 3: 82 percent / xylene / 0.25 h / Heating 4: 1) O3, 2) Me2S / 1) -65 deg C, 2) r.t., 1h View Scheme

1: 92 percent / xylene / 0.25 h / Heating 2: 1) O3, 2) Me2S / 1) -65 deg C, 2) r.t. View Scheme