1: 92 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 50 °C 2: 92 percent / trioctylphosphine, carbon tetrabromide / diethyl ether / 0.22 h / 0 °C 3: 1.) butyllithium, 2.) 3-methoxy-3-methylbut-1-ynylcopper 4: 1.) LiAlH4, 2.) PCC, AcONa / 1.) Et2O, 10 min, 2.) dichloromethane, RT, 1 h 5: 62 percent / P2I4 / 0.42 h / 0 °C View Scheme

Multi-step reaction with 2 steps 1: 92 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 50 °C2: 92 percent / trioctylphosphine, carbon tetrabromide / diethyl ether / 0.22 h / 0 °C  

With  silver tetrafluoroborate in  benzene T=80°C; 2.5 h;   

Multi-step reaction with 4 steps 1: 92 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 50 °C2: 92 percent / trioctylphosphine, carbon tetrabromide / diethyl ether / 0.22 h / 0 °C3: 1.) butyllithium, 2.) 3-methoxy-3-methylbut-1-ynylcopper4: 1.) LiAlH4, 2.) PCC, AcONa / 1.) Et2O, 10 min, 2.) dichloromethane, RT, 1 h  

With  pyridinium p-toluenesulfonate in  ethanol T=50°C; 4 h;   

Multi-step reaction with 3 steps 1: 92 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 50 °C2: 92 percent / trioctylphosphine, carbon tetrabromide / diethyl ether / 0.22 h / 0 °C3: 1.) butyllithium, 2.) 3-methoxy-3-methylbut-1-ynylcopper