On the Functionalization of C60 with Vinylallenes Generated in situ by Rhodium Catalysis

The functionalization of fullerenes is important for several reasons, primarily related to enhancing their chemical reactivity, solubility, and potential of applications in optoelectronics and biomedicine. In this study, we present a novel approach to functionalize C60 through a cascade process encompassing an unprecedented Rh-catalyzed cycloisomerization of 1,6-allenynes to in situ generate a vinylallene that is followed by a Diels-Alder reaction with pristine fullerene, resulting in the formation of 6,6-fused bicyclic fullerene derivatives. The mechanism governing this process was elucidated by DFT calculations and confirmed by deuterium labelling and control experiments, demonstrating the critical role of traces of water in the reaction medium to mediate the observed reactivity.