1: 54 percent / t-BuLi, iodine / pentane; tetrahydrofuran / -78 deg C, 75 min; RT, 30 min 2: 66 percent / 10 percent H2SO4 / 15 h / Heating 3: 99 percent / Et3N, CuI / bis(triphenylphosphine)palladium(II) chloride / tetrahydrofuran / 5 h / Ambient temperature 4: 51 percent / CuI / dimethylformamide / 2 h / Heating View Scheme

1: 54 percent / t-BuLi, iodine / pentane; tetrahydrofuran / -78 deg C, 75 min; RT, 30 min 2: 66 percent / 10 percent H2SO4 / 15 h / Heating 3: 99 percent / Et3N, CuI / bis(triphenylphosphine)palladium(II) chloride / tetrahydrofuran / 5 h / Ambient temperature 4: 51 percent / CuI / dimethylformamide / 2 h / Heating 5: 38 percent / 33 percent acetic acid / H2O / 4 h / Heating View Scheme