1: 54 percent / toluene / 2 h / 370 °C 2: 96 percent / aq. HCl / tetrahydrofuran / 0.08 h 3: 91 percent / diisobutylaluminum hydride / tetrahydrofuran; hexane / 0.5 h / Ambient temperature 4: 62 percent / trifluoroacetic acid, dimethyl sulfoxide / CH2Cl2 / 1 h / -78 °C View Scheme