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 C(60)(MeOOCCH)(2)NC(O)R, R = (CH(2))(5)Br, (CH(2))(8)C(O)Cl (3), (CH(2))(4)C(O)Cl, or cis-C(6)H(4)(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 C(60)(MeOOCCH)(2)NC(O)(CH(2))(8)COOH (4). Treating 4 with PCl(5) 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 [bond] C(O), the rotation barrier of which is 15.06 kcal/mol. The relative stereochemistry of the 2,5-dimethoxycarbonyl groups is established by (1)H NMR spectra and further confirmed by resolution of the enantiomeric 2,5-trans-isomer of the starting material 1.
Zhang
Sheng
S
Department of Chemistry and Instrumental Analysis Center, Peking University, Beijing 100871, China.
Gan
Liangbing
L
Huang
Chunhui
C
Lu
Mujian
M
Pan
Jinqi
J
He
Xiaoran
X