Synthesis of dicarboxylic acid derivatives of [60]fullerene using Diels–Alder reaction with bis(methylene)butanedioates

3-Sulfolene-3,4-dicarboxylates effective for generation of bis(methylene)butanedioates were applied to [4+2] cycloaddition reaction of C60 to give fullerocyclohexenedicarboxylates, among which a t-butyl ester was hydrolyzed to a dicarboxylic acid derivative, useful for further conversion into its anhydride and half-esters.