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

4 A molecular sieve; toluene-4-sulfonic acid 1.) benzene, 6 h, reflux, 2.) benzene, 2 h, reflux; Yield given. Multistep reaction;

1: 85.6 percent / lithium / tetrahydrofuran; diethyl ether / 0.75 h / -25 °C 2: oxygen, water / benzene / 0 °C View Scheme