General Route from Simple Methyl, Alkyl, and Cycloalkyl Arenes to Polycyclic Cyclopentenyl Aryl Derivatives. The CpFe⁺ Group as an Activator and Tag

The CpFe⁺ group activates the perallylation of the benzylic groups of arenes using KOH and allylbromide under ambient conditions. This reaction can be followed by ruthenium-catalyzed RCM metathesis using Grubbs' catalyst at room temperature to give polycyclic aromatic derivatives in high yields, and these products are easily separated from the catalyst by extraction using ether. Alternatively, the RCM metathesis can be best carried out in ionic liquids at 80 °C, and extraction using ether is then facile.