Base-iodine-promoted metal-catalyst-free reactions of [60]fullerene with ß-keto esters for the selective formation of [60]fullerene derivatives.

In this study, methanofullerenes and 2',3'-dihydrofuran C60 derivatives were selectively synthesized in high yields via the reactions of C60 with ß-keto esters under mild conditions by controlling the addition sequence and molar ratio of iodine and base. The structures of the products were determined by spectroscopic characterization. Moreover, a possible reaction mechanism for the selective formation of fullerene derivatives was proposed.

1H-Imidazol-3-ium-4-carboxyl-ate.

In the title compound, C(4)H(4)N(2)O(2), both imidazole N atoms are protonated and carboxyl-ate group is deprotonated, resulting in a zwitterion. The mol-ecule is essentially planar, with an r.m.s. deviation of 0.012 (1) Å. In the crystal, N-H⋯O hydrogen bonds and π-π stacking inter-actions [centroid-centroid distance = 3.674 (2) Å] between the imidazole rings link the mol-ecules into a three-dimensional supra-molecular network.