Synthesis And Application Of Dendritic Catalysts

Organometallic dendrimer catalyst has been attracting much attentiondue to its unique chemical and physical properties. In thecore-functionalitied dendrimer the catalyst could sepecially benefitfrom the "site isolation" effect and the excellent solubility caused bythe dendritic structure. In this thesis, we designed and synthesised twonew classes of organometallic dendrimers with the catalytically activecenter at the focal point of the dendrimers. These dendritic catalystswere successfully applied to catalystic reactions and some scientificresults were obtained as follows.Based on the concept of"one phase catalysis / two phase seperation",two new types of dendritic ligands for immobilizing tetroxide osmiumhave been synthesised using p-aminopyridine and tetrasubstitutedolefin as starting materials. The formation of osmium complexes wereinvestigated and the catalyst activities of the two kindsdendrimer-bouded osmium complexes were compared by using thedihydroxylation of cyclohexene as the standard reaction. A novelcatalysis system has been developped for highly effectivedihydroxylationA new class of BINOL-based chiral monodentate phosphitedendrimer ligands have been synthesized and fully characterizedusing different analysis techniques. These dendritic ligands weresuccessfully applied to the Rh-catalyzed asymmetric hydrogenation ofα-dehydroamino methyl cinnamate. Some interesting preliminaryresults were obtained. It was found that the enantioselectivities have II湘潭大学硕士论文 题目:树状大分子催化剂的设计合成及其应用been improved along with the increase of the size of dendrimers.Most interestingly, similar reactivity and enantioselectivities wereobserved when the reaction was carried out under high ligand/Rhratio (up to 3:1). This findings will lay a good foundation for studingcatalystic mechanism of chiral monodentate phosphite-Rh catalyst.