1: p-toluenesulfonic acid / benzene / Heating 2: 1.) NaI, 2.) aq. HCl / 1.) reflux, 48 h, 2.) from 80 deg C to RT, 16 h 3: 1.) BuLi / 1.) THF, heptane, from -78 to -65 deg C, 1 h, 2.) from -75 to -65 deg C, 2 h View Scheme

1: 1.) NaI, 2.) aq. HCl / 1.) reflux, 48 h, 2.) from 80 deg C to RT, 16 h 2: 1.) BuLi / 1.) THF, heptane, from -78 to -65 deg C, 1 h, 2.) from -75 to -65 deg C, 2 h View Scheme

n-butyllithium 1.) THF, heptane, from -78 to -65 deg C, 1 h, 2.) from -75 to -65 deg C, 2 h; Yield given. Multistep reaction;