Preparation Of Magnetically Supported Chiral Ruthenium/rhodium Catalysts And Their Catalytic Properties

Magnetic nanocatalyst materials have attracted widespread attention in recent years due to their remarkable catalytic activity and recyclability of magnetic separation.This specificity not only simplifies the relatively complicated post-treatment steps of other supported catalysts,but also improves the recycling capacity of heterogeneous catalysts.Recent studies have shown that organic silicon or inorganic silicon coated magnetic nanoparticles can effectively overcome the shortcomings of magnetic aggregation,their morphology is easy to control,and the surface is easy to modify,making the magnetic nanoparticles easy to support various types of catalysts.Moreover,the silicon-based magnetic nanoparticles have good affinity for both water and oil phase solvents,and they are not easy to aggregate in the solvent,so that the silicon-based magnetic nanoparticles are used as the catalyst to greatly improve the heterogeneity.Phase catalysis efficiency,which has better enantioselectivity control in the catalysis of organic chiral molecules.This article explores cascade reactions and asymmetric catalytic reactions by designing egg-yolk-shell and core-shell magnetic nanoparticles.The main research content is divided into the following two parts.1)We synthesized mesoporous egg yolk-shell structured magnetic nanoparticles by hydrothermal method and St?ber method using cetyltrimethylammonium bromide(CTAB)as a template.Silica is used as a carrier to fix the chiral Ru/diamine ligand in the nanochannels of the outer mesoporous silicone shell,and the ferric chloride is adsorbed on the inner magnetic core to realize the separation of the active sites of the catalyst,so that the two A kind of mutually influencing catalysts can coexist in a catalyst carrier,thus constructing a dual-functional magnetic catalyst.This dual-functional catalyst can realize an effective oxygen sulfonylation/asymmetric transfer hydrogenation one-pot cascade reaction,thereby synthesizing a series of?-hydroxysulfones with higher yield and enantioselectivity.Application experiments show that the magnetic catalyst has good magnetic separation and stability,and it still has good reactivity and enantioselectivity after repeated application for more than 6times.2)We use(S,S)-Ts-DPEN and silica to directly coat ferroferric oxide nanoparticles to prepare a core-shell type magnetic nano-catalyst carrier.[Cp*Rh Cl₂]₂ is directly attached to the surface of the catalyst carrier.The magnetic chiral rhodium nanocatalyst prepared by complexing with diamine ligands exhibits excellent catalytic activity and stereoselectivity in the asymmetric transfer hydrogenation of aromatic ketones,thereby preparing various preparations with high yield and enantioselectivity.For chiral aromatic alcohols,the yield and ee value of the corresponding target product are as high as 99%and 99%,respectively.Application experiments show that the magnetic catalyst has good magnetic separation and stability,and it still has good reactivity and enantioselectivity after repeated application for more than 6 times.