Study On The Chemical Selectivity Control Of Aromatic Dialdehydes Based On Nitrogen Heterocyclic Carbene Catalysi

The furo[2,3-b] pyrrole derivative skeleton is a very important structural unit,which widely exists in various natural products and pharmaceutical active molecules.Due to its unique activity and wide application range,it has caused organic Highly regarded by chemists in the field of synthesis.How to construct such complex compounds through simple,efficient and convenient synthetic strategies has always been a research focus,hot spot and difficulty in this field.As a special small molecule catalyst,NHeterocyclic Carbene(NHC)can not only control the progress of high-yield and highstereoselective reactions through its unique activation mode and flexible structural modification,but also It can simply,quickly and efficiently synthesize many novel framework compounds that cannot be obtained by traditional methods through the activation modes of different sites.In this paper,oxidation of Breslow intermediates to form acylazolium intermediates,which react with N-substituted imine substrates,can be obtained in one step by exploiting the selective activation of newly synthesized asymmetric enedialdehydes by azacyclic carbene A class of compounds with the skeleton of furo[2,3-b] pyrrole derivatives.In this paper,we realized the selective activation of azacyclic carbene for intramolecular unequal formyl groups through the substrate design of asymmetric enedialdehyde,achieving high regioselectivity,high chemoselectivity and high stereoselectivity,Finally,furo[2,3-b] pyrrole derivatives skeleton-like compounds were formed with high optical purity,and a series of transformation and mechanism studies were carried out.This article is mainly described in the following three parts:The first part: mainly describes the history and current situation of research on NHeterocyclic Carbene at home and abroad,mainly describes the reaction of NHeterocyclic Carbene catalyzed activation of different sites in the past few decades,mainly focusing on in situ,α,β,γ,δ Classical representative responses for isopositions.And different from the active site research,the focus is on the selective attack of the NHeterocyclic Carbene between the non-equivalent formyl groups,mainly describing the chemical selectivity and the intermolecular and intramolecular non-equivalent formyl groups in recent years.The research of regioselectivity found that the research mainly focused on the different formyl groups between the two molecules,while the intramolecular research was carried out less.The second part: mainly describes the research significance and goals of this topic.Through the investigation and research of previous literatures,it is found that furan[2,3-b] pyrrole derivative skeletons widely exist in natural product molecules and medical functional molecules,and they have antibacterial properties.It has excellent biological activities such as mitosis,acetylcholine inhibitor,and anticancer,so it has received extensive attention and high attention in the field of organic synthesis.At the same time,the strategies and methods for the synthesis of related furo[2,3-b] pyrrole derivatives were reviewed,such as a series of methods based on modified indole structure,modified five-membered heterocycle or multi-component reaction construction.Part III: mainly describes the selective activation of intramolecular asymmetric olefinic dialdehydes catalyzed by nitrogen-Heterocyclic Carbene with N-substituted acetophenone-type imines through high regioselectivity,high chemoselectivity,high Enantioselective one-step synthesis of highly optically pure furo[2,3-b] pyrrole derivatives skeleton compounds.After the determined model reaction,the type of catalyst,the type and strength of base,the type of solvent,and the reaction system were determined.The optimal conditions of the model reaction were established by screening the temperature,concentration and other conditions,and then the universality study of the substrate and the transformation and derivation of the target product molecule were carried out,and then the deuterium experiment and mechanism study showed the level of selectivity.The oxidation rates of the Breslow intermediates formed between the two aldehydes differed and the desired results were finally achieved.