Isoprene and benzenoid hydrocarbons having unoccupied vicinal positions combine, in the presence of sulfuric acid, to give indans. These indans may react with a second mole of isoprene to form hydrindacenes. Mesitylene, which is incapable of direct cyclialkylation, condenses with isoprene, in the presence of methanesulfonic acid, to yield olefin intermediates. These intermediates may be cyclized with concomitant methyl group ...
