Playing with Protic Additives to Improve the Outcome of Rhodium‐Catalyzed Hydroarylation of Fullerene C₆₀ with Arylboronic Acids

Abstract

A new one‐phase process for hydroarylation of C60 fullerene using aryl boronic acids and a rhodium catalyst in an aromatic solvent containing soluble protic additives is described. Yields of monohydroarylated product with tert‐butanol and water as the protic additive range from 14 to 50% depending on which arylboronic acid is used after reaction times of 4 hours or less which is a significant improvement from the outcome of reactions carried out using conditions from the literature. Accurate monitoring of reaction outcomes was achieved by a combination of UV‐Vis spectroscopy and 1H NMR spectroscopy: C60 conversion was determined using an analytical HPLC – UV‐vis method employing commonly available columns for the separation, while product formation was quantified by 1H NMR spectroscopy with an internal standard. Moreover, two new arylboronic acids carrying 4‐alkynyl aryl substituents, synthesized using Sonogashira couplings, are reported, as well as the use of these in the hydroarylation of C60.