Study On The Reaction Of Electrochemical C-N Bonding To Construct Heterocyclic Compounds

Nitrogen-containing heterocycles are a very important class of organic compounds,and various nitrogen-containing heterocyclic structures are widely found in biologically active natural products,organic materials,agricultural chemicals,and pharmaceuticals.The construction of nitrogen containing heterocyclic compounds with high efficiency and selectivity has always been one of the core research topics in modern organic synthesis.In recent years,electrochemical organic synthesis has made remarkable progress in the application of constructing nitrogen-containing heterocyclic compounds,causing widespread attention.The construction of heterocyclic compounds based on electrochemical implementation of novel cyclization reactions is a more efficient and green synthesis method.In this paper,the basic principles of organic electrochemical synthesis were introduced first,and the research progress in electrochemical synthesis of nitrogen containing heterocyclic compounds was reviewed in detail.Based on this,this thesis has developed a series of efficient and green intermolecular cycloaddition reactions using electrochemical methods,starting from easily available reaction substrates such as benzenesulfonyl hydrazone and nitrosobenzene.The main contents of the study are as follows:（1）Under electrochemical conditions,[1,2,4]triazolo[4,3-a]pyridine was synthesized by cyclization reaction.In an integrated cell equipped with a carbon rod as an anode and a platinum plate as a cathode,we used easily available aryl hydrazone compounds as a reaction substrate to undergo intermolecular cyclization with electron deficient pyridines under 5 mA electrolysis conditions to construct C-N bonds,and synthesized a series of triazole compounds in yields ranging from 35%to 61%.Wherein a catalytic amount of thiaanthracene is used as an indirect oxidant to initiate the reaction and achieve a catalytic cycle.From the perspective of organic synthesis methodology,the electrochemical construction of[1,2,4]triazolo[4,3-a]pyridine has important research and practical significance.（2）Cyclization of nitroso aromatic hydrocarbons and secondary amine/imination reactions under electrochemical conditions.Under the condition of constant current electrolysis,we conducted a study on the cyclization reaction using readily available nitroso aromatic hydrocarbons and acetylacetone compounds.A series of secondary amines and imines were synthesized through an electroreduction reaction in an integrated cell equipped with zinc sheets as anodes and carbon rods as cathodes,using CH₃CN/H₂O as a mixed solvent,at 0℃,with a yield of 48%to 98%.Compared with traditional methods,the reaction conditions are mild and do not require additional reductants and transition metal catalysts.