Enhanced reactivity of Li + @C 60 toward thermal [2 + 2] cycloaddition by encapsulated Li + Lewis acid.

Lithium ion-endohedral fullerene (Li + @C 60 ), a member of the burgeoning family of ion-endohedral fullerenes, holds substantial promise for diverse applications owing to its distinctive ionic properties. Despite the high demand for precise property tuning through chemical modification, there have been only a few reports detailing synthetic protocols for the derivatization of this novel material. In this study, we report the synthesis of Li + @C 60 derivatives via the thermal [2 + 2] cycloaddition reaction of styrene derivatives, achieving significantly higher yields of monofunctionalized Li + @C 60 compared to previously reported reactions. Furthermore, by combining experimental and theoretical approaches, we clarified the range of applicable substrates for the thermal [2 + 2] cycloaddition of Li + @C 60 , highlighting the expanded scope of this straightforward and selective functionalization method.