triethylamine; lithium bromide 1.) THF, 10 min, r.t.; 2.) 2 h, -20 deg C; 3.) r.t., 3 h; Yield given. Multistep reaction. Yields of byproduct given. Title compound not separated from byproducts;

1: 1.) TiCl4 / 1.) dichloromethane, -78 deg C, 30 min, 2.) dichloromethane, -50 deg C, 18 h 2: sodium hydride / tetrahydrofuran / 2 h / Ambient temperature View Scheme

Multi-step reaction with 2 steps 1: 1) MgCl2, Et3N / 1) toluene, room temperature, 2 h, 2) room temperature, 6 h2: p-TsOH / H2O / 4 h / Heating