The Application Of 3D Hollow Bimetallic Cobalt-Iron Oxides In Organic Synthesis

Metal oxide nanoparticles are widely used as heterogeneous catalysts due to their easy separation and recyclability.In recent decades,with the rapid development of metal oxide nanotechnology,the application of metal oxide nanoparticles in the field of catalysis has become an important research field.For example,Fe3O4 nanoparticles as catalysts have been successfully used in Cross Dehydrogenative Coupling(CDC)and Aldehyde-alkyne-amine three-component coupling reaction(A3 coupling reaction).Among them,the CDC reaction cross-coupling to form C-C bonds through intermolecular dehydrogenation under oxidation conditions,without any pretreatment of the reaction substrate.There are no other leaving groups during the reaction,so shorter synthetic routes and higher reaction efficiency are achieved while by-product emissions are reduced.The 1-nitromethyl-N-aryltetrahydroisoquinoline derivatives produced by the Aza-Henry CDC reaction between nitroalkanes and Naryltetrahydroisoquinolines are an important class of heterocyclic compounds that can be used in the development and diagnosis of new drugs.Naturally occurring as well as synthetic tetrahydroquinoline/isoquinoline have many different biological activities and have been shown to be significantly cytotoxic in human cancer cells.The A3 coupling reaction product propargylamine compound is an important part and backbone of bioactive compounds.It is not only an intermediate for the preparation of many kinds of nitrogenous compounds(such as euthanine,rasagiline maleate,etc.),but also a key component of a variety of biologically active substances(such as β-lactams,herbicides,fungicides and alkaloids).Therefore,it is of great research significance to use metal oxide nanoparticles heterogeneous catalysts to catalyze correlation reactions to synthesize medicinally active chemical molecules.However,the use of a single metal oxide ferric oxide to catalyze related reactions has been reported in the literature,which has problems such as harsh reaction conditions,lack of effective active site exposure,and sluggish mass transfer.Therefore,a cobalt-iron bimetallic oxide nanocatalyst with a three-dimensional structure was designed and prepared in order to further reduce the reaction activation energy through bimetallic synergistic effect,so that the reaction can be carried out under mild conditions.In addition,by constructing hollow or open nanoframe structures,more active sites are exposed,and mass transfer is improved in the reaction.The Aza-Henry CDC reaction and A3 coupling reaction are proposed to verify the catalytic activity in the application of the new catalyst,and the main research contents and results are as follows:(1)Hollow prismatic cobalt-iron Prussian blue analogues(P-CoFe-PBAs)were calcined to cobalt-iron bimetallic oxides(P-CoFeOx)with similar morphology,and applied to catalyze the Aza-Henry CDC reaction and A3 coupling reaction.P-CoFeOx can catalyze the Aza-Henry CDC reaction at 60℃ aerobic conditions with isolated yield of 75-93%.P-CoFeOx was used to catalyze the A3 coupling reaction,and the A3 coupling reaction could be efficiently catalyzed under the condition of 80℃ under air with isolated yield of 82-94%.(2)Framed cobalt-iron Prussian blue analogues(F-CoFe-PBAs)were calcined to obtain cobalt-iron bimetallic oxides F-CoFeOx)with similar morphology,and applied to catalyze the Aza-Henry CDC reaction and A3 coupling reaction.F-CoFeOx can also efficiently catalyze the Aza-Henry CDC reaction under aerobic conditions at 60℃ with isolated yield of 70-91%.F-CoFeOx was used to catalyze the A3 coupling reaction,and the A3 coupling reaction could be catalyzed under the condition of 80℃ under air with isolated yield of 82-94%.Compared with the solid Fe3O4 nano-catalyst,the above two catalysts can effectively reduce the reaction temperature and realize the relevant organic transformation under mild conditions.Its universality was demonstrated by substrate scope exploration.In the process of post-treatment,it is found that the catalyst can be recycled by magnet.The experimental characterization showed that the structure and morphology of the catalyst were basically the same before and after the reaction.Cycling experiments demonstrated the stability and reusability of the catalyst.