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

With  carbon tetrabromide; tri-n-octyl phosphine in  diethyl ether T=0°C; 0.216667 h;   

Multi-step reaction with 3 steps 1: 92 percent / trioctylphosphine, carbon tetrabromide / diethyl ether / 0.22 h / 0 °C2: 1.) butyllithium, 2.) 3-methoxy-3-methylbut-1-ynylcopper3: 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 2 steps 1: 65 percent / AgBF4 / benzene / 2.5 h / 80 °C2: 92 percent / pyridinium p-toluenesulfonate / ethanol / 4 h / 50 °C  

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