1: in diethyl ether 2: With hydrogenchloride; water 0.05 h; 3: With sodium hydride in tetrahydrofuran; methanol T=20°C; 3 h;

1.1: 50 percent / bromine / CCl4 / 5 h / 0 - 5 °C 2.1: 81 percent / triethyl orthoformate; p-toluenesulfonic acid monohydrate / 4 h / 20 °C 3.1: nBuLi / tetrahydrofuran / 1 h / -78 °C 3.2: 86 percent / tetrahydrofuran / 2 h / -78 °C 4.1: 4.60 g / p-toluenesulfonic acid monohydrate / CH2Cl2 / 2 h / 20 °C 5.1: diethyl ether 5.2: HCl; water / 0.05 h 5.3: 72 percent / NaH / tetrahydrofuran; methanol / 3 h / 20 °C View Scheme

1.1: 81 percent / triethyl orthoformate; p-toluenesulfonic acid monohydrate / 4 h / 20 °C 2.1: nBuLi / tetrahydrofuran / 1 h / -78 °C 2.2: 86 percent / tetrahydrofuran / 2 h / -78 °C 3.1: 4.60 g / p-toluenesulfonic acid monohydrate / CH2Cl2 / 2 h / 20 °C 4.1: diethyl ether 4.2: HCl; water / 0.05 h 4.3: 72 percent / NaH / tetrahydrofuran; methanol / 3 h / 20 °C View Scheme

1.1: nBuLi / tetrahydrofuran / 1 h / -78 °C 1.2: 86 percent / tetrahydrofuran / 2 h / -78 °C 2.1: 4.60 g / p-toluenesulfonic acid monohydrate / CH2Cl2 / 2 h / 20 °C 3.1: diethyl ether 3.2: HCl; water / 0.05 h 3.3: 72 percent / NaH / tetrahydrofuran; methanol / 3 h / 20 °C View Scheme

1.1: 4.60 g / p-toluenesulfonic acid monohydrate / CH2Cl2 / 2 h / 20 °C 2.1: diethyl ether 2.2: HCl; water / 0.05 h 2.3: 72 percent / NaH / tetrahydrofuran; methanol / 3 h / 20 °C View Scheme