Preparation And Catalytic Properties Of Imidazolium-based Organic-inorganic Hybrid Silicon Material Catalyst

Imidazolium-Based organic-inorganic hybrid silica (IBOIHS) can be easilymanufactured and modified. As a functional platform, it can be regarded as aphase-transfer catalyst. When it is utilized in multiphase reactions, it displays a greateffect. It has a lot of advantages, such as high thermal stability, enormous hydroxylswhich can be modified. These hydroxyls are separated well in the surface and theactive points are uniformed. The material shows an open microstructure which iseasy for the substrates to approach so that the reaction can get high catalytic activityand enantioselectivity. Furthermore, imidazolium salt can be considered as acarbenoid and can match with the metal. On the basis of all the advantages of thismaterial, we made three kinds of catalysts with it and explored their catalytic activity.(1) The preparation and catalytic properties ofCp*RhTsDPEN-IBOIHS/DACH-NiDACH-IBOIHS: We made the (S,S)-Ts-DPEN and grafted it on the Imidazolium-Based organic-inorganic hybrid silica (IBOIHS). Then, we got the Ts-DPEN-IBOIHS.After that, we let the Ts-DPEN-IBOIHS complex with the [Cp*RhCl2]2and then thecatalyst Cp*RhTsDPEN-IBOIHS. We used it in the asymmetric transformation ketonereactions. As demonstrated in the studies, it displays comparable or even highercatalytic activity and enantioselectivity than its homogeneous counterpart inasymmetric transformation. Moreover, it can be conveniently recovered and reusedat least10times without loss of its catalytic efficiency. At the meantime, we madebis(cyclohexyldiamine)-based Ni(II) complex, abbreviated as DACH-Ni-DACH whichwas anchored conveniently within this functionalized IBOIHS material to give thecatalyst DACHNiDACH-IBOIHS. Again, the excellent catalytic activity andenantioselectivity in asymmetric Michael addition of malonates to nitrostyrenes wasobtained in this case. So, the materials as immobilized chiral organic metal catalystplatform possess excellent performance.(2) The preparation of NHC-Pd-IBOIHS and "one-pot" two-step synthesis of chiral biaryl alcohols: We let the Pd(OAc)2anchored in the functionalized IBOIHSmaterial to give the catalyst N-heterocyclic carbenoid-Pd catalyst(NHC-Pd-IBOIHS).The catalyst was used in the series reaction of Suzuki-Miyaura and was applied to aone-pot synthesis of chiral biaryl alcohols. Realized for the first time the bimetallic"one-pot" two-step synthesis of chiral biaryl alcohols, two catalysts showed highercatalytic performance.