Regioselective Addition of N-(4-Thiocyanatophenyl)pyrrolidine Addends to Fullerenes

The regioselectivity of 1,3-dipolar cycloaddition reactions between N-(4-thiocyanatophenyl)glycine and tetrakis[bis-(ethoxycarbonyl)methylenel-C-60 (7) was studied. The mono-addition resulted in two penta-adduct isomers (8 and 9) in a 1:1 ratio. A second addition to each compound led to, in the case of 8, two hexa-adduct isomer products (10 and 11), whereas addition to 9 led to 11 and 12. Finally, reaction of 11 and the glycine afforded a third addition, giving rise to hepta-adduct isomers 13 and 14. Preparative TLC and column chromatography were used to separate and purify these compounds. The structures were assigned based on their molecular symmetries as analyzed by H-1, C-13, and 2D NMR spectra and MALDI-TOF MS. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)