1: 70 percent / LiCl; DBU / tetrahydrofuran / 1 h / -78 °C 2: 85 percent / TMSOTf / CH2Cl2 / 20 h / -78 °C 3: 65 percent / MeONa / benzene / 12 h / Heating 4: 90 percent / MgCl2 hexahydrate / dimethylsulfoxide / 4 h / 130 °C View Scheme