1: p-toluenesulfonic acid / toluene / 2.5 h / Heating 2: 1.) n-BuLi / 1.) hexane, THF, from -100 deg C to -78 deg C, 1 h 25 min, 2.) hexane, THF, -70 deg C, 1 h View Scheme

n-butyllithium 1.) hexane, THF, from -100 deg C to -78 deg C, 1 h 25 min, 2.) hexane, THF, -70 deg C, 1 h; Multistep reaction;