toluene-4-sulfonic acid in benzene 4.6 h; Heating;

1: CrO3, 3,5-dimethylpyrazole / CH2Cl2 / 0.17 h 2: 92 percent / H2O; methanol / 48 h / Ambient temperature 3: 1.) Mg / 1.) THF, 2.) THF, reflux, 24 h 4: etheral HCl View Scheme