1: With iodine in tetrahydrofuran; dibromoethane, 1,2- 0.75 h; Heating / reflux; 2: With copper(l) iodide in tetrahydrofuran; dibromoethane, 1,2-; dimethylsulfide T=-30°C; 2 h;

magnesium in tetrahydrofuran T=40°C; 1 h;

in tetrahydrofuran T=-78 - 20°C; Inert atmosphere;

1: 2.) trifluoroacetic acid / 1.) Et2O, -40 deg C, 3 h, 2.) Et2O, -78 deg C, 1 h 2: 1.25 h / 120 °C 3: AcOH, Zn / 24 h / Ambient temperature View Scheme