1: 1.) SeO2, 2.) NaBH4 / 1.) EtOH, reflux, 4 h 2: 48 percent / triphenylphosphine, CCl4 / 4 h / Heating 3: 1.) n-butyl lithium / 1.) a) -78 deg C, 0.5 h, b) 0.5 h, r.t. 2.) THF, -78 deg C, 0.5 h 4: 82 percent / (n-Bu)4NF / tetrahydrofuran / 18 h / Heating 5: 1.) n-BuLi, 2.) Li, EtNH2 / 1.) THF, 2.) -78 deg C, 20 min View Scheme