1: p-TosOH / xylene / 5.5 h / Heating 2: tetra-n-butyl ammonium hydrogen sulfate, NaOH / CH2Cl2; H2O / 16 h / Ambient temperature 3: LiBu / tetrahydrofuran; hexane / 0.33 h / -78 °C 4: p-TosOH / 1 h / 190 °C 5: 480 mg / BBr3 / CH2Cl2 / 1) -78 deg C, 2) -78 deg C to r.t. overnight View Scheme

toluene-4-sulfonic acid in xylene 5.5 h; Heating; Yield given;