Asymmetric Cascade Reactions To Construct The Pyran-Pyrrole Scaffold

Heterocycles are important structural motif that is usually found in natural products with various bio-activities and in functional organic molecules including organic dye molecules,organocatalysts etc.Traditional synthetic approaches to heterocyclic compounds usually use condensation reactions or cycloaddition reactions under harsh conditions such as high temperature and the use of toxic reagents.The development of efficient and concise methods to construct chiral polyheterocyclic compounds is one of the hot fields in organic synthesis.Since 2000,asymmetric reactions catalyzed by organic molecules have developed rapidly and are widely used in the synthesis of a variety of chiral molecules.The cascade reaction achieves the goal of rapid synthesis in a short-time,economical,feasible,ecologically compatible and stereoselective way.Dioxopyrrolidone compounds with high reactive keto groups can be used as active substrates for the construction of dicyclic pyranes,and dicyclic pyranes can be used for the development of new drugs and the synthesis of natural products.Therefore,this paper mainly studies the series reaction of organic catalyzed dioxypyrrolidine compounds.This thesis is divided into four chapters.In chapter 1,the development history of organic small molecule catalysis and the classical models of organic small molecule catalysis are summarized.In chapter 2,firstly,the reaction mode of the modularly designed organoccatalysts and reactions involved in dioxopyrrolidones are briefly introduced.Secondly,we reported a Michael addition-acetalation/oxa-Michael reaction dioxopyrrolidones and aldehydes catalyzed by modularly designed organoccatalysts(MDOs)to provide a novel method for construction the tricyclic pyran-pyran-pyrrole skeleton,asymmetric cascade reaction of dioxopyrrolidones and aldehydes was catalyzed by the selfassembly catalysts of 10 mol%cinchona alkaloid catalysts QDT and 10 mol%L-proline,and obtained tricyclic pyran-pyran-pyrrole compounds with moderate to high yield and excellent enantioselectivity.In chapter 3,firstly,vinylogous reactions are classified,and the latest research progress of pyrazole amide has been carried on the brief overview.Secondly,we reported the asymmetric vinylogous Aldol/cyclohexylation reaction catalyzed cinchona alkaloid derived catalyst with dioxopyrrolidines and pyrazole amide.The reaction provides concise and effective method to build pyran spiropyrrole skeleton.Asymmetric vinylogous Aldol/cyclohexylation reaction with dioxypyrrolidine and pyrazolamide obtained pyran spiropyrrole with excellent yield and enantioselectivity,catalyzed by 10 mol%bifunctional cinchona alkaloid catalysts.The chapter 4,we summarize the work of this paper.In summary,we investigated two types of organic catalysts of the asymmetric Michael additionacetalation/oxa-Michael reactions and vinylogous Aldol/cyclohexylation reactions,and the ractions synthesized tricyclic pyrano-pyrano[2,3-c]pyrrole derivatives and pyrans spiropyrrole compounds,providing a basis for future studies and applications.