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Regiocontrol of mutiple fullerene derivatization is important for producing derivatives with specific functions. In previous reports,[1]it was found that bis 1,3-dipolar cycloaddition (Prato reaction) can proceed in a regioselective manner in the case of trimetallic nitride template endohedral metallofullerene, (TNT-EMFM3N@C80, M = Sc, Lu, Y, Gd), while less regioselectivity is usually observed in the case of C60. This is presumably due to the effect of the endohedral metal cluster inside the C80and – especially in case of bis-addition reaction – the position of second addition sites seem to be dependent on the ionic radii of the metal. In this study, we used a larger excess of the dipole in the Prato reaction of M3N@C80(M = Y, Gd). After a short reaction interval, sufficient amounts of tri and tetra adducts were obtained, in addition to the bis-adducts. Although the adducts were not single isomers (four tris-adducts and mono-tetra adduct), the reaction occurred in regioselective manners. All generated tris- and tetra-adducts of M3N@C80 (M = Y, Gd) were isolated by HPLC. The structures of the tris-and tetra-adducts of Y3N@C80were established by 1H and 13C NMR. Reference: [1]. Aroua, S.; Garcia-Borràs, M.; Bölter M. F.;, Osuna, S.*; Yamakoshi, Y.*: Endohedral Metal-Induced Regioselective Formation of Bis-Prato Adduct of Y3N@Ih-C80 and Gd3N@Ih-C80, J. Am. Chem. Soc. 2015, 137, 58-61; Cerón, M. R.; Izquierdo, M.; Garcia-Borràs, M.; Lee, S. S.; Stevenson, S.; Osuna, S.; Eshegoyen, L.: Bis-1,3-dipolar Cycloadditions on Endohedral Fullerenes M3N@Ih-C80 (M = Sc, Lu): Remarkable Endohedral-Cluster Regiochemical Control, J. Am. Chem. Soc. 2015, 137, 11775 – 11782. |
