Hydroarylation of Fullerene C60 Using Arylboronic Acids via Rhodium Catalysis : Improving the Outcomes and Simplifying the Conditions

Sammanfattning: Hydroarylation with arylboronic acids is one of the functionalization methods for synthesis of modified fullerenes. In this work, we provide a fast and reproducible one-phase method for hydroarylation of fullerene using boronic acids and an analytical HPLC method that efficiently separates unreacted C60 and product from a hydroarylation reaction mixture as well as a fulleropyrrolidine reaction mixture. This analytical method was not only successively applied to preparative scale to isolate the functionalized fullerenes but also validated for quantification of unreacted C60 in the reaction mixtures together with 1H NMR quantification used for the hydroarylated product. Reaction conditions screening was done by investigating the effects of solvents, time and temperature, protic additive, catalyst amount and different substituents on arylboronic acid. It was found that the reaction gives the best outcome when it is done at 110 °C for 4h, using anhydrous methanol or tert-butanol:water mixture as protic additives and 10 mol % [Rh(cod)(MeCN)2]BF4 as catalyst. Both the conversion and the product yield were found higher than the reported values.