Rh-Catalyzed Cycloaddition of C60 with Enynes: Unveiling the Mechanistic Pathway

Abstract

In this study we present a method for functionalizing C60 through a Rh-catalyzed cyclization reaction with 1,6-enynes, resulting in the formation of a fused bicyclic structure. Additionally, fullerene derivatives are further functionalized through regioselective photooxygenation reactions. Our DFT calculations reveal two distinct reaction pathways: one involving rhodium-catalyzed cycloisomerization of the enyne followed by Diels-Alder with C60, and the other featuring a rhodium-catalyzed [2+2+2] cycloaddition of enyne and C60 followed by isomerization. Surprisingly, both pathways exhibit nearly identical energy barriers. However, experimental tests indicate that the predominant pathway varies depending on the substitution motifs of the substrates