1: 76 percent / NaOMe / methanol / 12 h / 20 °C 2: 99 percent / tetrahydrofuran; diethyl ether / 1.5 h / 20 °C 3: 95 percent / TBAF / tetrahydrofuran / 3 h 4: 61 percent / p-toluenesulfonic acid / benzene / 48 h / 60 °C 5: 76 percent / CuBr2 / acetonitrile / 72 h / 50 °C 6: 71 percent / Li2CO3; LiBr / dimethylformamide / 17 h / 140 °C View Scheme