Electrochemical Activation of the Least Reactive Endohedral Fullerene: Sc3N@Ih-C80

The low reactivity of endohedral fullerenes compared with empty fullerenes makes their functionalization and further applications very challenging. To overcome their low reactivity, part of our research is focused on exploring alternative synthetic pathways for their functionalization. Some examples include the exohedral functionalization through photochemical reactions and electrosynthesis. Electrochemical methods in particular provide control over the state of oxidation/reduction of the endohedral compounds. Extensive research has been done with anionic empty fullerenes species but until recently, only some anionic endohedral fullerenes used as nucleophilic reagents have been explored. However, cationic radical species of endohedral compounds as electrophilic reagents for exohedral functionalizations have never been reported. Furthermore, regioselective and enantioselective addition reactions are also not well studied. Using electrochemical methods of endohedral fullerenes we can tune the HOMO-LUMO energy levels of the species in play to perform reactions that are unsuccessful by other methods. Herein, we report the first asymmetric 1,3-dipolar cycloaddition using the cation radical of Sc₃N@I_h-C₈₀ through both electrochemical and chemical pathways using controlled potential electrolysis and chemical oxidation, respectively.