Diels–Alder cycloadditions of fullerene: Advances in mechanistic theory

Fullerene exhibits a wealth of interesting characteristics owing to its unique π-electron configuration. The structure and properties of fullerene can be manipulated by introducing chemical groups to the carbon–carbon bonds via organic reactions, extending its application field. The Diels–Alder (DA) cycloaddition reaction is commonly used to decorate the carbon cage of fullerene. Furthermore, atoms, ions, clusters, and molecules can be inserted into the hollow carbon cage of a fullerene, thereby changing the electron transfer process within the fullerene cage and thus the reactivity of the as well as the regioselectivity of the DA cycloaddition reaction. Computer-based theoretical modeling is an essential tool for studying chemistry. Herein, we provide a brief review of theoretical investigations into the cycloaddition mechanism of two most common fullerenes (C₆₀ and C₇₀), especially in terms of the effects of encapsulated chemical species based on the distortion–interaction model. We hope that the current mini review will provide a useful and interesting resource for researchers working on—or simply being interested in—the in silico investigation of fullerenes and their DA-based modification.