Nowadays, a complete understanding of fullerenes chemical reactivity has been achieved and, in this regard, we have demonstrated that a full control in the stereoselective functionalization of fullerenes is also possible, by using different asymmetric metal- and organo-catalyzed processes.¹ Furthermore, fullerenes and transition metals have given rise to a wide set of sophisticated metallo-fullerene hybrids.² However, despite the rich chemistry developed “onto fullerenes”, the chemistry carried out “with fullerenes” has been almost neglected. Thus, an intriguing and still open question is whether fullerenes could be involved in promoting or catalysing chemical transformations and, in particular, if fullerene double bonds are suitable to act in transfer hydrogenation processes.

In order to address these questions, we have designed and prepared a fullerene hybrid where C₆₀is endowed with a metal atom, such as Ir, that has shown to have a high activity in transfer hydrogenation reactions. Thus, a new hybrid iridium-fullerene  has been synthesized in which the fullerene moiety, far from being innocent, plays a leading role as a multi-site carbon-based hydrogen transfer catalyst. [60]Fullerene, analogously to NAD(P)H, acts as a hydrogen borrowing molecule by the reversible uploading of hydrogen. The highly efficient reduction of ketones with isopropanol as hydrogen donor, or the N-alkylation of amines with alcohols catalyzed by iridium-fullerene represent the first examples of fullerenes as catalysts in chemical reactions.

References

1. a) Maroto, E. E.; Izquierdo, M.; Reboredo, S.; Marco-Martínez, J.; Filippone, S.; Martín, N. Acc. Chem. Res. 2014, 47, 2660. b) Filippone, S.; Maroto, E. E.; Martín-Domenech, A.; Suárez, M.; Martín, N. Nat. Chem. 2009, 1, 578; c) Maroto, E. E.; Mateos, J.; Garcia-Borràs, M.; Osuna, S.; Filippone, S.; Herranz, M. Á.; Murata, Y.; Solà, M.; Martín, N. J. Am. Chem. Soc. 2015, 137, 1190. 

2. a) Lebedeva, M. A.; Chamberlain, T. W.; Khlobystov, A. N. Chem. Rev. 2015, 115 (20), 11301; (b) Matsuo, Y.; Nakamura, E. Chem. Rev. 2008, 108, 3016.