1.1: 87 percent / p-toluenesulfonic acid / toluene / Heating 2.1: Li; naphthalene / tetrahydrofuran / 3 h / -40 °C 2.2: tetrahydrofuran / 0.5 h / -40 °C 3.1: H2SO4 / H2O; tetrahydrofuran / 1 h / 20 °C View Scheme

1.1: Li; naphthalene / tetrahydrofuran / 3 h / -40 °C 1.2: tetrahydrofuran / 0.5 h / -40 °C 2.1: H2SO4 / H2O; tetrahydrofuran / 1 h / 20 °C View Scheme

1.1: hydrogenchloride / tetrahydrofuran; water / 11 h / 0 - 20 °C 2.1: trimethylsilyl trifluoromethanesulfonate; triphenylphosphine / dichloromethane / 1 h / 20 °C / Inert atmosphere 2.2: 2 h / -40 - 20 °C / Inert atmosphere 2.3: 2 h / 40 °C View Scheme

1.1: magnesium / tetrahydrofuran / Inert atmosphere 1.2: 5 h / 0 °C / Inert atmosphere 2.1: hydrogenchloride / tetrahydrofuran; water / 11 h / 0 - 20 °C 3.1: trimethylsilyl trifluoromethanesulfonate; triphenylphosphine / dichloromethane / 1 h / 20 °C / Inert atmosphere 3.2: 2 h / -40 - 20 °C / Inert atmosphere 3.3: 2 h / 40 °C View Scheme

1.1: magnesium / tetrahydrofuran / Inert atmosphere 1.2: 5 h / 0 °C / Inert atmosphere 2.1: hydrogenchloride / tetrahydrofuran; water / 11 h / 0 - 20 °C 3.1: trimethylsilyl trifluoromethanesulfonate; triphenylphosphine / dichloromethane / 1 h / 20 °C / Inert atmosphere 3.2: 2 h / -40 - 20 °C / Inert atmosphere 3.3: 2 h / 40 °C View Scheme