Application of ultrasound technique in the synthesis of methanofullerene derivatives Original Research Article

Methanofullerene derivatives C60(CCl2) (1a), C60(CBr2) (1b), C60(CI2) (1c) and C121 (2) were synthesized in 55–84% yields by dehalogenation of the corresponding α-polyhalides via sodium hydroxide, magnesium, respectively, followed by the in situ reaction with fullerene under the irradiation of ultrasound in a non-conventional reaction media, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4]. Only single [6,6]-ring junction cycloaddition isomers of the products were detected in the reaction solutions under our conditions. In contrast, low yields of 6–21% were obtained when the same reactions were operated in tetrahydrofuran. All of the products were purified with HPLC and characterized by 13C NMR and FAB-MS.