Multi-step reaction with 3 steps 1: 1.) n-BuLi / 1.) THF, hexane, 0 deg C, 3 h, 2.) -78 deg C, 15 min2: 1.) 50percent NaH in mineral oil / 1.) THF, reflux, 0.5 h, 2.) DMF, THF, reflux, 5 min3: 1.) n-BuLi, 2.) C2Cl6 / 1.) THF, hexane, 0 deg C, 3 h, 2.) 0 deg C, 1 h