Sol-gel immobilized of ligands for copper-catalyst arylation of oxygen nucleophiles
Our aim was to develop a way to synthesize diarylethers using copper catalyted ligands immobilized on silyl-organic inorganic materials prepared by sol-gel. The interest of these heterogeneous systems is that they are recyclable and reusable, less polluting and less toxic due to their ability to sequester metal catalyst. This is particularly important for use of diaryléthers obtained in pharmaceutical industry. We managed to synthesize by sol-gel process materials incorporating bipyridine or β-dicarbonyl type ligands. These materials were then applied in copper-catalyzed arylation of phenols by aryl iodides and bromides. The new heterogeneous catalysts have yielded good results in arylation of oxygen nucleophilies and also in terms of recovery and reuse. In addition, diaryléthers products are obtained "clean" of copper traces used in catalysis. The method we developed is therefore particularly competitive in terms of cost, pollution and residual toxicity. It is to our knowledge the first example of ligand supported on silica by sol-gel and applied in copper-catalyzed arylation of phenols.