1: 1) LDA, 2) bromine / 1) THF, -75 deg C, 4 h, 2) -75 deg C, 0.5 h 2: 1) n-BuLi, TMEDA / 1) Et2O, -60 deg C, 0.5 h, 2) Et2O, -75 deg C, 2 h 3: 85 percent / MnO2 / toluene / 12 h / Heating 4: 65 percent / PTSA / toluene / 24 h / Heating 5: 1) LDA, 2) iodine / 1) THF, -75 deg C, 4 h, 2) THF, -75 deg C, 3 h View Scheme

1: 1) n-BuLi, TMEDA / 1) Et2O, -60 deg C, 0.5 h, 2) Et2O, -75 deg C, 2 h 2: 85 percent / MnO2 / toluene / 12 h / Heating 3: 65 percent / PTSA / toluene / 24 h / Heating 4: 1) LDA, 2) iodine / 1) THF, -75 deg C, 4 h, 2) THF, -75 deg C, 3 h View Scheme

1: 65 percent / PTSA / toluene / 24 h / Heating 2: 1) LDA, 2) iodine / 1) THF, -75 deg C, 4 h, 2) THF, -75 deg C, 3 h View Scheme

1: 85 percent / MnO2 / toluene / 12 h / Heating 2: 65 percent / PTSA / toluene / 24 h / Heating 3: 1) LDA, 2) iodine / 1) THF, -75 deg C, 4 h, 2) THF, -75 deg C, 3 h View Scheme