1: toluene-4-sulfonic acid / benzene / 80 °C 2: tetrabutyl ammonium fluoride / tetrahydrofuran 3: potassium hexamethylsilazane / tetrahydrofuran / 0 °C 4: Grubb's 2nd generation catalyst / toluene / 80 °C 5: toluene-4-sulfonic acid / water; acetone / 40 °C 6: aluminium(III) iodide; tetra-(n-butyl)ammonium iodide; 1,3,5-trishydroxybenzene / benzene / 5 °C View Scheme