Alkylation of dihydrofullerenes

The fulleride dianions C₆₀^2- and C₇₀^2- were generated by deprotonation of the corresponding hydrogenated fullerenes, 1,2-C₆₀H₂ and 1,2-C₇₀H₂. These anions were prepared in the presence of a variety of alkylating agents, and mono- or dialkylated products were obtained. Alkylation was not successful with sulfonate ester alkylating agents. Deprotonation of monoalkylated compounds, followed by second alkylation with a different alkylating agent, produced heterodialkylated compounds. The monoalkyated material was invariably the 1,2-isomers, while the dialkylated materials were generally 1,4-isomers, although some 1,2-isomer was observed in the C₇₀ context. The major product from alkylation of C₇₀^2- was the 7,23-isomer 13a, a structure where the alkylation took place near the equator of the fullerene cage, rather than at the more strained carbons near the poles.