1.1: 95 percent / (trifluoromethyl)methyldioxirane / CH2Cl2 / 2 h / -20 °C 2.1: 96 percent / i-Pr2NEt; DMAP / CH2Cl2 / 24 h / 20 °C 3.1: HMDS / tetrahydrofuran / 2 h / -60 °C 3.2: 60 percent / tetrahydrofuran / 17 h / -60 - -5 °C 4.1: t-BuLi / diethyl ether; pentane / 0.5 h / -78 °C 4.2: ZnBr2 / tetrahydrofuran; diethyl ether; pentane / -78 - -10 °C 4.3: 75 percent / Et3N / (Ph3P)4Pd / tetrahydrofuran; diethyl ether; pentane / -40 - 20 °C 5.1: 95 percent / n-Bu4NF / tetrahydrofuran / 2 h / 20 °C View Scheme