Anomalous Cis ‐Conformation Regioselectivity of Heterocycle‐Fused Sc 3 N@ D 3 h ‐C 78 Derivatives

Endohedral clusterfullerenes exhibit unique chemical properties due to intramolecular electron transfer of the encaged metal cluster to the outer fullerene cages. We report the synthesis of two Sc 3 N@ D 3 h ‐C 78 monoadducts 2 a and 2 b through the 1,3‐dipolar reaction of Sc 3 N@ D 3 h ‐C 78 with carbonyl ylide bearing anomalous cis ‐conformation regioselectivity. The molecular structures of these monoadducts are unambiguously confirmed by single‐crystal X‐ray crystallography, revealing that both 2 a and 2 b have cis ‐conformations with the furan moiety grafted via [6,6]‐closed addition patterns. Under the same conditions, the control reaction of C 60 with carbonyl ylide affords two monoadducts 3 a and 3 b , which exhibit cis ‐ and trans ‐conformations, respectively, with [6,6]‐closed addition patterns. According to theoretical calculations, the exclusive formation of the cis ‐only Sc 3 N@ D 3 h ‐C 78 monoadducts is a consequence of conjunct effects of thermodynamic stability of adducts, the reactivity of the addition site, and the cis ‐dipole intermediate from trans 1 .