Study On The Synthesis Of Quinoxaline Compounds Catalyzed By Nitrogen Heterocyclic Carbene And Their Biological Activity

Quinoxaline and its derivatives are important organic synthesis units which widely found in natural products,pharmaceuticals and pesticide molecules.The synthesis of quinoxalines has been given considerable attention.However,how to synthesized chiral quinoxaline compounds with green,simple and mild reaction conditions in one step,especially synthesis of high yield and high stereoselectivity quinoxaline compounds has been research emphasis and difficulties in the field of organic synthesis.As a small organic catalyst,N-Heterocyclic Carbenes(NHC)has the advantages of simple operation,non-toxic,mild conditions and environmental friendliness.It can quickly construct new compounds with novel structures which cannot be synthesized by traditional methods.At present,the synthesis of chiral quinoxaline derivatives by NHC catalytic activation has been rarely reported.Therefore,this thesis mainly studies the synthesis of quinoxaline compounds by NHC catalytic activation of ?-chloroaldehyde and cyclohexadiene-1,2-diimine,and the preliminary study on the biological activity of the target compounds.1.Using NHC to catalyze the [4+2] cycloaddition reaction between ?-chloroaldehyde(form a nucleophilic enolate intermediate)and cyclohexadiene-1,2-diimine to construct chiral quinoxaline compounds with a simple and efficient process.After optimization of the model reaction conditions and substrate scope,the er value of all the different substituted quinoxaline compounds at least greater or equal to 96:4 and the yield up to 94%.The target compound obtained according to model reaction could transformed to new compounds with high yields and er values in further derivatization2.By using the turbidity method,the target compounds with different substituents and derivatives were test on the antibacterial activity against Xanthomonas oryzae pv.Oryzae with two concentrations of 100 ?g/mL and 200 ?g/mL.The results showed that the derivative tetrahydroquinoxaline 7 has antibacterial activity comparable to commercial drugs,while other compounds are not as effective as commercial drugs.