1: 100 percent / H+ / tetrahydrofuran 2: 81 percent / NaBH4 / aq. ethanol / 1.) 0 deg C, 5 min, 2.) room temperature, 5 min 3: 91 percent / Ph3PBr2 / acetonitrile 4: 89 percent / acetonitrile / 24 h / Heating 5: 60 percent / NaN(SiMe3)2 / tetrahydrofuran / 1.) room temperature, 1 h, 2.) -90 deg C 6: 93 percent / LiOH / tetrahydrofuran; H2O View Scheme

1: 100 percent / H+ / tetrahydrofuran 2: 81 percent / NaBH4 / aq. ethanol / 1.) 0 deg C, 5 min, 2.) room temperature, 5 min 3: 91 percent / Ph3PBr2 / acetonitrile 4: 89 percent / acetonitrile / 24 h / Heating 5: 60 percent / NaN(SiMe3)2 / tetrahydrofuran / 1.) room temperature, 1 h, 2.) -90 deg C View Scheme

hydrogen cation in tetrahydrofuran

1: 100 percent / H+ / tetrahydrofuran 2: 81 percent / NaBH4 / aq. ethanol / 1.) 0 deg C, 5 min, 2.) room temperature, 5 min View Scheme

1: 100 percent / H+ / tetrahydrofuran 2: 81 percent / NaBH4 / aq. ethanol / 1.) 0 deg C, 5 min, 2.) room temperature, 5 min 3: 91 percent / Ph3PBr2 / acetonitrile View Scheme

1.1: TsOH 2.1: sodium bis(trimethylsilyl)amide / tetrahydrofuran / 1.17 h / -40 - 20 °C 2.2: 73 percent / tetrahydrofuran / 4 h / 0 °C 3.1: p-toluenesulfonic acid / tetrahydrofuran; H2O / 0.33 h / Heating 4.1: sodium bis(trimetylsilyl)amide / tetrahydrofuran / 1 h / 0 °C 4.2: 53 percent / tetrahydrofuran / -100 - 20 °C 5.1: p-toluenesulfonic acid / tetrahydrofuran; H2O / 0.25 h / Heating View Scheme

1.1: TsOH 2.1: sodium bis(trimethylsilyl)amide / tetrahydrofuran / 1.17 h / -40 - 20 °C 2.2: 73 percent / tetrahydrofuran / 4 h / 0 °C 3.1: p-toluenesulfonic acid / tetrahydrofuran; H2O / 0.33 h / Heating 4.1: 91 percent / sodium borohydride / methanol / 0.17 h / 0 °C 5.1: 86 percent / triphenylphosphine; carbon tetrabromide / CH2Cl2 / 2 h / 20 °C View Scheme