Acylation of 2,5-dimethoxycarbonyl[60]fulleropyrrolidine and synthesis of its multifullerene derivatives.

2,5-Dimethoxycarbonyl[60]fulleropyrrolidine (1) is acylated with various chlorocarbonyl compounds to give fullerene derivatives with the general formula C60(MeOOCCH)2NC(O)R, R = (CH2)5Br, (CH2)8C(O)Cl (3), (CH2)4C(O)Cl, or cis-C6H4(C(O)Cl. The monoacylated sebacoyl derivative 3 readily reacts with alcohols and amines such as methanol, diethylamine, glycine methyl ester, and aza-18-crown-6 through the remaining chlorocarbonyl group. Chromatography of 3 on silica gel converts it into the corresponding acid C60(MeOOCCH)2NC(O)(CH2)8COOH (4). Treating 4 with PCl5 regenerates the precursor 3 quantitatively. Piperazine reacts with 4 in the presence of DCC and BtOH to form a bisfullerene derivative in which two sebacoyl chains and the piperazine act as the bridge between two molecules of 1. Other molecules with multifunctional groups react with 4 similarly to form multifullerene derivatives. NMR data indicate that the rotation of the relatively bulky phthaloyl group is hindered around the amide bond N−C(O), the r...