1: 89 percent / PCC, MS 4A / CH2Cl2 / 1 h / Ambient temperature 2: 88 percent / PPh3 / CH2Cl2 / 0.08 h / 0 °C 3: 82 percent / BuLi / hexane; tetrahydrofuran / 0.17 h / -78 °C 4: 76 percent / Ni(acac)2, DIBAH, PPh3 / hexane; tetrahydrofuran / 18 h / Ambient temperature View Scheme