1: 96.2 percent / 10percent HCl / tetrahydrofuran / 1 h 2: 2.) 4-Angstroem molecular sieves / 1.) p-toluenesulfonic acid / 1.) benzene, 6 h, reflux, 2.) benzene, 2 h, reflux View Scheme

hydrogenchloride in tetrahydrofuran 1 h;

1: 96.2 percent / 10percent HCl / tetrahydrofuran / 1 h 2: 2.) 4-Angstroem molecular sieves / 1.) p-toluenesulfonic acid / 1.) benzene, 6 h, reflux, 2.) benzene, 2 h, reflux 3: 85.6 percent / lithium / tetrahydrofuran; diethyl ether / 0.75 h / -25 °C 4: oxygen, water / benzene / 0 °C View Scheme

Multi-step reaction with 4 steps 1: 96.2 percent / 10percent HCl / tetrahydrofuran / 1 h2: 2.) 4-Angstroem molecular sieves / 1.) p-toluenesulfonic acid / 1.) benzene, 6 h, reflux, 2.) benzene, 2 h, reflux3: 85.6 percent / lithium / tetrahydrofuran; diethyl ether / 0.75 h / -25 °C4: oxygen, water / benzene / 0 °C  

Multi-step reaction with 3 steps 1: 96.2 percent / 10percent HCl / tetrahydrofuran / 1 h2: 2.) 4-Angstroem molecular sieves / 1.) p-toluenesulfonic acid / 1.) benzene, 6 h, reflux, 2.) benzene, 2 h, reflux3: 85.6 percent / lithium / tetrahydrofuran; diethyl ether / 0.75 h / -25 °C  

Multi-step reaction with 2 steps 1: 90.6 percent / lithium / tetrahydrofuran; diethyl ether / 2.5 h / 0 °C2: 80 percent / pentane / 1.) 0 deg C, overnight, 2.) room temperature, 5 days