Noncovalent Anchoring of Homogeneous Catalysts to Silica Supports with Well-Defined Binding Sites

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• 作者：Ruifang Chen ; Raymond P. J. Bronger ; Paul C. J. Kamer ; Piet W. N. M. van Leeuwen ; and Joost N. H. Reek
• 刊名：Journal of the American Chemical Society
• 出版年：2004
• 出版时间：November 10, 2004
• 年：2004
• 卷：126
• 期：44
• 页码：14557 - 14566
• 全文大小：154K
• 年卷期：v.126,no.44(November 10, 2004)
• ISSN：1520-5126

文摘

The efficient reversible functionalization of silica with catalytic sites using noncovalent interactionsis described. We prepared silica materials with well-defined binding sites that selectively bind guest moleculesthat are equipped with the complementary binding motif, with the interaction between the two componentsbeing based on either hydrogen bonds or metal-ligand interactions. Several phosphine ligands functionalizedwith glycine-urea groups, required for hydrogen bond formation to the complementary host on the silica,have been prepared. The resulting noncovalently immobilized complexes have been used as a ligand systemin the Pd-catalyzed allylic substitution and Rh-catalyzed hydroformylation of 1-octene. The supramolecularinteraction between the transition-metal catalyst and the binding site located at the support is sufficientlystrong to enable efficient catalyst recycling. In addition, the nature of the support facilitates the de- andrefunctionalization of support, allowing the recycling of both homogeneous catalysts and the functionalizedsupport. A rhodium catalyst based on a functionalized xantphos ligand was used in the hydroformylationof 1-octene in 11 consecutive reactions without showing catalyst deterioration or metal leaching.