1: With boron trifluoride diethyl etherate; ethylene glycol in dichloromethane T=20°C; 2: With hydrogenchloride in tetrahydrofuran 24 h;

1.1: LDA / tetrahydrofuran; hexane / 0.75 h / -78 °C 1.2: 90 percent / tetrahydrofuran; hexane / 1 h 2.1: 94 percent / PPTS / benzene / 1.5 h / Heating 3.1: LiAlH4 / tetrahydrofuran / 0.17 h / 0 °C 3.2: 76 percent / aq. HCl / tetrahydrofuran / 0.5 h / 20 °C 4.1: BF3*Et2O; ethylene glycol / CH2Cl2 / 20 °C 4.2: 75 percent / aq. HCl / tetrahydrofuran / 24 h View Scheme

1.1: LDA / tetrahydrofuran; hexane / 0.75 h / -78 °C 1.2: 88 percent / tetrahydrofuran; hexane / 4 h / -78 - 20 °C 2.1: LDA / tetrahydrofuran; hexane / 0.75 h / -78 °C 2.2: 90 percent / tetrahydrofuran; hexane / 1 h 3.1: 94 percent / PPTS / benzene / 1.5 h / Heating 4.1: LiAlH4 / tetrahydrofuran / 0.17 h / 0 °C 4.2: 76 percent / aq. HCl / tetrahydrofuran / 0.5 h / 20 °C 5.1: BF3*Et2O; ethylene glycol / CH2Cl2 / 20 °C 5.2: 75 percent / aq. HCl / tetrahydrofuran / 24 h View Scheme

1.1: 93 percent / sulfuric acid / benzene / 20 h / Heating 2.1: LDA / tetrahydrofuran; hexane / 0.75 h / -78 °C 2.2: 88 percent / tetrahydrofuran; hexane / 4 h / -78 - 20 °C 3.1: LDA / tetrahydrofuran; hexane / 0.75 h / -78 °C 3.2: 90 percent / tetrahydrofuran; hexane / 1 h 4.1: 94 percent / PPTS / benzene / 1.5 h / Heating 5.1: LiAlH4 / tetrahydrofuran / 0.17 h / 0 °C 5.2: 76 percent / aq. HCl / tetrahydrofuran / 0.5 h / 20 °C 6.1: BF3*Et2O; ethylene glycol / CH2Cl2 / 20 °C 6.2: 75 percent / aq. HCl / tetrahydrofuran / 24 h View Scheme

Yield given. Multistep reaction;