Ring-closing metathesis versus cross metathesis of resin-bound olefins

Resin-bound di-olefins were treated to metathesis conditions and both intramolecular ‘ring-closing’ metathesis (RCM) and intermolecular ‘cross’ metathesis were observed. Mono-olefin analogs produced dimers in high yield via intermolecular metathesis, despite being polymer-bound. The majority of resin-bound olefin molecules are able to come within reacting distance and 1% crosslinked polystyrene offers little or no ‘site separation’. This demonstrates a method to use olefin metathesis with the potential to prepare compound libraries on resin by dimerizing simple olefins into more complex molecules.