Facile attachment of functional moieties to crosslinked polystyrene beads via robust linkages: Suzuki reactions using polymer-supported boronic acids

Abstract

Aryl bromides containing carboxylic acid, alcohol, phenol, amine, triphenylphosphine, sulfonamide, thiophene or furan moieties were linked directly to polystyrene beads containing boronic acid groups by Suzuki reactions. In all cases except that with 2-bromofuran, the coupling yields were greater than 50%. In several cases those boronic acid residues that did not take part in the Suzuki reaction were lost by hydrolysis of the B–C bond; in other cases the remaining residues could be removed easily by Suzuki reactions using an excess of bromobenzene. The Suzuki reaction therefore provides an easy means to attach functional moieties to polystyrene beads via robust linkages without the need for protecting groups and without leaving in the beads any of the reactive groups used in the linking reaction. It should be noted that using the polymer-supported boronic acid allows functionalised aryl halides to be attached, whereas the reverse type of Suzuki reaction would require functionalised arylboronic acids. Functionalised aryl halides are more accessible than functionalised arylboronic acids.