1: 93 percent / dimethylsulfoxide / 2 h / 8 °C 2: 79 percent / n-butyllithium / tetrahydrofuran; hexane / 1.5 h / 0 °C 3: 84 percent / glacial acetic acid, triphenylphosphine / toluene / 48 h / Heating 4: 88 percent / SN<N(TMS)2>2 / hexane / 12 h / Ambient temperature View Scheme