Application of ultrasound technique in the synthesis of methanofullerene derivatives

Abstract

Methanofullerene derivatives C 60(CCl 2) ( 1a), C 60(CBr 2) ( 1b), C 60(CI 2) ( 1c) and C 121 ( 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][BF 4]. 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.