Synthesis Of Substituted 1,2,4-Triazole Derivatives By Electrochemical Dehydrocyclization Reaction

Electrochemical organic synthesis realizes the redox reaction through the process of gaining and losing electrons on the electrode surface,effectively avoiding the use of chemical oxidants or reducing agents,and control pollution from the source of chemical conversion.It has the advantages of green,high efficiency and high selectivity.1,2,4-triazole heterocyclic structural units are widely present in natural products,medicines and functional materials,play an important role in modern pharmacy and organic chemistry.This thesis studies the synthesis of substituted 1,2,4-triazole derivatives by electrochemical dehydrocyclization.The main contents of this thesis are as follows:In the first chapter,organic electrochemical synthesis is overviewed and the development history of organic electrochemistry is briefly reviewed,then in recent years,the development of organic electrochemical synthesis at home and abroad has been reviewed.It includes four aspects:"Electrochemical reaction to build C-C bond","Electrochemical reaction to build C-N bond","Electrochemical reaction to build C-O bond",and"Electrochemical reaction to build C-S and N-S bond".In the second chapter,the reported methods are reviewed for the synthesis of substituted 1,2,4-triazole derivatives.In the third chapter,the electrochemical dehydrogenation[3+2]cyclization reaction using hydrazones and amines as substrates to synthesize a series of substituted1,2,4-triazole derivatives is carried out in detail.Using cheap and easily available hydrazone derivatives and amines as raw materials,30 target compounds were synthesized in high yield under electrocatalytic conditions.The reaction does not need to add any oxidants,transition metal catalysts,acids or bases.The reaction substrate has a wide application range,and gram scale amplification experiments can also be carried out.Both allylamine and propargylamine can react to achieve alkenylation、alkynylation and alkylation of the 1,2,4-triazole skeleton.Their structures were confirmed by ¹H NMR,¹³C NMR and HRMS analyses.In the fourth chapter,the electrochemical multi-component[3+1+1]cyclization is studied by using hydrazone,aldehyde and NH₄OAc as substrates derivative.The advantage of this strategy is that the inorganic salt NH₄OAc provides a nitrogen source,and 27 target compounds are obtained without transition metals,acids,bases and external oxidants.Their structures were confirmed by ¹H NMR,¹³C NMR and HRMS analyses.The reaction conditions are mild and the atom economy is high,the gram-level reaction is completed with a high yield,which provides an efficient and green synthesis route for obtaining 1,2,4-triazole derivatives.