Study On The Catalytic Reactions Of π Systems And Allyl Alcohols Activated By Chalcogen-Bonding Interaction

Chalcogen bond is a non-covalent interaction between the divalent chalcogens as Lewis acid and the electron-rich Lewis base.This interaction plays an important role in biological systems,and has been applied to the fields of material science.The current catalysis research on chalcogen bond mainly focuses on the interaction between chalcogens and lone-pair electrons,namely Ch…n(n→σ*)the reaction types and catalytic modes are relatively simple.This paper proposed the concept of chalcogen…π bonding interactions between chalcogens and π-electron cloud of aromatic systems,namely Ch…π(π→σ*),and realized the Diels-Alder reaction of vinylindole.This thesis further developed the catalytic reactions and modes of chalcogen bond,and realized the allylation reaction of allyl alcohols.Part 1:Study on chalcogen…π bonding catalysisWeak interactions between sulfur atom and aromatic rings are widespread by analysizing the protein crystal database.Based on our previous research,we proposed the chalcogen…π bonding catalysis.The crystal structure of the catalyst shows that there are intermolecular and intramolecular weak interactions between the chalcogens and the π systems.This weak interaction is further confirmed by nuclear magnetic resonance experiment.Studies have shown that the interaction of S…π and Se…π can effectively drive the Diels-Alder reaction of vinylindole.Competition experiments have shown that the addition of Lewis bases can affect the Se…π interaction and inhibit the cycloaddition reaction.We proposed the double Se…π bonding interaction mechanism and verified the reaction mechanism through a series of control experiments.For this cycloaddition reaction,the monodentate catalyst has low activity and poor selectivity,while the bidentate catalyst shows high catalytic activity and can well control the stereoselectivity of the reaction.The study of the reaction mechanism shows that the π-π interaction plays an important role in controlling the stereoselectivity.This catalysis mode provides enlightenment for the follow-up study of of chalcogen…π bonding catalysis,and expands the scope of weak interaction ability.Part 2:Study on the allylation reaction catalyzed by chalcogen bondChalcogens are often used as Lewis base catalysts because of their electron donating ability.Whether chalcogens have similar reaction properties to metal catalysts is the goal of further research.The allylation reaction catalyzed by transition metals is an important organic reaction to construct carbon-carbon bonds and carbon-heterobonds.Not only the allyl alcohols are easy to obtain,but also the allylation products have important application value.In this paper,we realized the allylation reaction catalyzed by chalcogen bonding interactions.The allyl alcohols were activated by chalcogen bonding interactions,and then reacted with nucleophiles containing C,N,O,S to construct carbon-carbon bonds and carbon-heterobonds.In this thesis,we have carried out substrates expansion and mechanism exploration on the allylation reaction catalyzed by chalcogen bonding interactions,and discussed the problems arising in this research.This research developed the allylation reaction catalyzed by chalcogen bonding interactions,and provided new methods for exploring the new chemical properties of chalcogens.