[60]Fullerene-acene chemistry: a review

Acenes represent interesting platforms on which to add [60]fullerenes via Diets-Alder cycloaddition reactions. For unsubstituted acenes, the most reactive positions are the center-most rings. Large acenes can accommodate more than one [60]fullerene cycloaddition and these reactions become facile once suitable directing substituents (e.g. phenyl groups) are added to the acene. In these cases, [60]fullerenes add in a syn-diastereoselective fashion due to favorable pi-pi stacking interactions between adjacent [60] fullerene moieties. The pi-pi stacking interactions provide further stabilization to these adducts. Several cis-bis[60]fullerene-acene adducts have been prepared in modest to excellent yield and one cis,cis-tris[60]fullerene-heptacene adduct has also been prepared.