The Application Study Of Polyoxometalates Catalyzes Coupling Reactions Of Amines With Aldehydes/boronic Acids Compounds

Nitrogen-containing compounds occupy a very important position in the field of pharmaceutical chemistry and organic chemical synthesis.Various nitrogen-containing compounds can be prepared by carbon-nitrogen coupling reaction.Most of them play an important role in the fields of biology,medicine and chemical industry.However,there are still some challenges for this important research topic.For example,traditional catalytic systems often have problems such as metal residues,non-recyclability,poor selectivity,and narrow substrate range in the process of catalyzing carbon-nitrogen coupling reactions to construct C-N bonds,which limits its large-scale application in industry.Polyoxometalates have become the focus of attention due to their unique system configuration,excellent redox performance,and good environmental compatibility.In this paper,we take polyoxometalates as entry points to explore their application in carbon and nitrogen coupling reactions by selecting two different types of Lindquist-type homopolysaccharides and Anderson-type heteropolysaccharides that possess classical conformations as catalysts.The specific contents are as follows:（1）Mo₆-Lindquist type isopolyoxometalates were selected as catalysts to catalyze the cross-coupling between amines and aldehydes to construct C-N bonds through reductive amination reactions.We used this catalyst in combination with Ph Si H₃ as the reducing agent and optimized the optimal reaction conditions by homogeneous catalytic modulation.We showed that the application of polymetallic oxides to the reductive amination reaction could achieve the N-alkylation of aldehydes with high selectivity and high yield,and the catalytic system was structurally stable and catalytically active.In addition,we investigated the reaction mechanism by controlled experiments,NIR analysis and ¹H NMR tracing studies.（2）Cu-Anderson type polyoxometalates were selected as catalysts to catalyze the cross-coupling between amines and boronic acids to construct C-N bonds via Cham-Lam coupling reaction.In this study,we explored the application of catalysts and determined the optimal reaction conditions by controlling the single variable method.Studies have shown that the highly selective conversion of reactants can be achieved without adding alkali in the multi-acid catalyzed Cham-Lam coupling reaction,and the possible reaction mechanism was proposed through the experimental process and related literature reports.In addition,we carried out recycling experiments on the catalyst to discuss the service life and stability of the catalyst.