toluene-4-sulfonic acid 1.) 5 deg C, 2.) RT, 10 min;

1: 1.) n-BuLi / 1.) ether, hexane, RT, 15 min, 2.) 22 deg C, 1 h 2: 72 percent / H2, potassium carbonate / Lindlar catalyst / toluene / 3 h / 20 °C / 760 Torr 3: PBr3 / diethyl ether / 0.08 h / Ambient temperature 4: 69 percent / benzene / Heating 5: 78 percent / NaOCH3 / CH2Cl2; methanol / 1 h / -10 °C View Scheme