1: With hydrogenchloride in 1,4-dioxane; water T=20°C; 1.5 h; 2: With sodium hydroxide in dichloromethane; water

1.1: pyridine / dichloromethane / 20 °C 1.2: 1 h 2.1: toluene; tetrahydrofuran / 0 °C / Inert atmosphere 3.1: titanium tetraethoxide / tetrahydrofuran / Inert atmosphere; Reflux 3.2: -50 - 20 °C 3.3: 0 °C 4.1: hydrogenchloride / 1,4-dioxane; water / 1.5 h / 20 °C View Scheme

1.1: titanium tetraethoxide / tetrahydrofuran / Inert atmosphere; Reflux 1.2: -50 - 20 °C 1.3: 0 °C 2.1: hydrogenchloride / 1,4-dioxane; water / 1.5 h / 20 °C View Scheme

1.1: toluene; tetrahydrofuran / 0 °C / Inert atmosphere 2.1: titanium tetraethoxide / tetrahydrofuran / Inert atmosphere; Reflux 2.2: -50 - 20 °C 2.3: 0 °C 3.1: hydrogenchloride / 1,4-dioxane; water / 1.5 h / 20 °C View Scheme