1: 70 percent / diethyl ether / 1 h / Ambient temperature 2: 82 percent / SnCl4 / benzene / 0.5 h / 0 °C View Scheme

n-butyllithium; Methyltriphenylphosphonium bromide 1) Et2O, hexane, r.t., 4 h, 2) Et2O, 40 deg C, 19 h; Yield given. Multistep reaction;