Electrocatalytic C(sp3)-H Functionalization For The Construction Of Nitrogen-Containing Heterocyclic Compounds Induced By Iodide Salts

Nitrogen-containing heterocycles are widely existed in bioactive molecules and functional material molecules,and most of them exhibit good physiological activities.Thus,the construction of nitrogen-containing heterocycles compounds has always been the focus of organic chemists.However,traditional synthetic methods usually suffered from the usage of metals and chemical stoichiometric oxidants/reductants.The residues of metals often affect the effectiveness of the nitrogen-containing heterocycles molecules.In addition,it is a tedious work to remove the residual metals,which generally requires multiple steps,resulting in the generation of wastes.As for the usage of chemical stoichiometric oxidants/reductants,it often leads to some undesired reactions,decreasing the atomic economy of reactions.Organic electrochemistry as an environmentally friendly method,employes the "green"electrons as oxidants/reductants,avoiding or decreasing the usage of oxidants/reductants.Base on the above mentioned facts,we expect to achieve the synthesis of nitrogen-containing heterocycles by virtue of the anodically generated iodine in situ to induce C(sp3)-H functionalization.This dissertation is divided into two parts.The first part reviews the recent developments on the synthesis of nitrogen-containing heterocycles compounds by virtue of electrochemistry.In combination with our laboratory works,the second part mainly studies the synthesis of isatins derivatives and imidazo[1,5-a]quinolines skeletons via electrochemically induced iodide salts catalysis.1.Electrocatalytic construction of isatins induced by n-Bu4NI2'-Aminoacetophenones undergo a C(sp3)-H oxidation and a following intramolecular C-N bond formation by virture of a simply electrochemical oxidation in the presence of n-Bu4NI,providing various isatins with moderate to good yields.The reaction features mild conditions,a wide scope of substrates,high atom economy and no additional conducting salts.What is more,the reaction intermediates were detected by EPR,a radical-based pathway was proposed.This developed method represents a mild and green approach for the construction of isatins derivatives.2.Electrocatalytic construction of 1,3-disubstituted imidazo[1,5-a]quinolines induced by NH4IWe developed a facile and efficient approach for the electrosynthesis of 1,3-disubstituted imidazo[1,5-a]quinolines in aqueous medium under metals and chemical oxidants free conditions in the presence of NH4I.A wide scope of substrates,readily available starting materials and gram-scale experiments made this reaction practicality.3.Electrocatalytic construction of imidazo-fused N-heterocycles induced by NH4IBased on the above reaction,we achieved the synthesis of imidazo-fused N-heterocycles from the readily available methyl N-heteroaromatics with amines/amino acids via intermolecular dehydrogenation cross coupling.This reaction features metals and chemical oxidants free,broad substrate scope,high atom economy water tolerant and scalability.Furthermore,the electrolysis product can be further transformed into various 1,3-disubstituted imidazo[1,5-a]quinolines by on/off switching of the electric current in one pot.This method provides a facile and efficient approach for the synthesis of imidazo-fused N-heterocycles.4.Electrocatalytic three-component reactions for the construction of 3-cyanide-substituted imidazo-fused N-heterocycles induced by NH4IBased on the above reaction,we further realized the electrocatalytic three-component reactions for the synthesis of 3-cyanide-substituted imidazo-fused N-heterocycles with the addition of TMSCN.The reaction features a wide scope of substrates,readily available starting materials,mild conditions,metals and chemical oxidants free conditions.Furthermore,this reaction broadens the scope of electrocatalytic three-component reactions.It is worth noting that the reaction represents the first example for the synthsis of 3-cyanide-substituted imidazo-fused N-heterocycles,providing a simple and green method for the synthesis of 3-cyanide-substituted imidazo-fused N-heterocycles.Compared with the traditional methods,the usage of electrochemistry in the presence of iodide salts for the construction of nitrogen-containing heterocycles is an environmentally friendly method with high atom economy,since it avoids the usage of metals and chemical oxidants.In addition,the iodide salts can be served as both electrolytes and mediators,which have important scientific research value and practical application prospects for the synthesis of nitrogen-containing heterocycles compounds.