1: With tert.-butyl lithium in tetrahydrofuran; pentane T=-78°C; 0.833333 h; 2: With iodine in tetrahydrofuran; pentane T=20°C; 11 h; Further stages.;

1.1: n-BuLi / diethyl ether; hexane / 0.33 h / 0 °C 1.2: 74 percent / BF3*OEt2 / diethyl ether; hexane / 16 h / 20 °C 2.1: t-BuLi / tetrahydrofuran; pentane / 0.83 h / -78 °C 2.2: 84 percent / iodine / tetrahydrofuran; pentane / 11 h / 20 °C View Scheme

t-BuLi in tetrahydrofuran -78°C -> room temp.;

1: bromine / dichloromethane 2: n-butyllithium; boron trifluoride diethyl etherate / diethyl ether 3: iodine; tert.-butyl lithium / tetrahydrofuran View Scheme