Functionalization of fullerenes by transition metal catalyzed cyclization reactions: Insights into the mechanisms

Transition metal-promoted or catalyzed cyclization reactions represent one of the most powerful alternatives to design and prepare new fullerene-based materials fused to carbo- and heterocyclic rings of all sizes and incorporating all kinds of functional groups. This chapter comprehensively examines such reactions documented in the scientific literature, from the inception of fullerene chemistry, with a special focus on their mechanistic aspects. We specifically highlight reactions where fullerenes actively engage in the catalytic cycle, forming organometallic complexes with a transition metal catalyst. Furthermore, we delve into cascade reactions, wherein transition metal catalysis facilitates the formation of intermediates that subsequently react with fullerenes.