Study On The Chalcogen-Bonding Interaction Catalyzed Cycloaddition Reactions Of Aziridines With Alkenes And Alkynes

Divalent chalcogenides are commonly used as covalent Lewis bases for catalysis.However,non-covalent interactions between S…O were found in the crystal structure of some proteins in nature,which provides theoretical basis for its use as Lewis acid to activate some electron-rich substrates.This thesis designs a synergistic activation mode based on the chalcogen-bonding interactions.The catalysts with specific structures were used to activate suitable reactive sites in the substrates to catalyze the cyclization reaction of aziridine with alkenes and alkynes,in which a series of pyrrole ring derivatives can be prepared.Part 1.Chalcogen-bonding interactions catalyzed cycloaddition reactions of aziridines with alkenesWeak interactions are amongst the significant evolutionary forces that are smartly exploited by nature to modulate the conformation of proteins and to drive cellular reactions.Although noncovalent interactions have been demonstrated to be a versatile tool to catalyze reactions involving polarized reactants,this catalysis approach has its constraint boundary.Since the weak nature of noncovalent interactions restricts both the reactivity and the concentration of equilibrating supramolecular complex,it remains an unresolved problem that trapping the supramolecular species with nonactivated alkenes.The chalcogen-bonding interaction can catalyze the cyclization reaction of aziridine and non-activated olefins.And pyrrolidine derivatives can be obtained through this reaction.The envision is that a cooperative interaction strategy enabling the simultaneous two-fold chalcogen-bonding interactions with aziridine would enhance the activation ability and provide more stabilization of the supramolecular species,thus improving the reactivity.However,to match the confined Lewis basic binding sites in phenylsulfonyl protected aziridines,the use of bidentate chalcogen-bonding donors that is capable of precisely recognizing the proper Lewis basic sites of aziridine is critically important to give catalytic activity.In order to study the mechanism of this catalytic strategy,nuclear magnetic resonance experiments confirmed that different framework catalysts and aziridine have significantly different interactions,and the interaction trend is consistent with the reaction activity.Competition experiments have shown that the addition of Lewis bases can affect this interaction and inhibit the cycloaddition reaction.These experimental results show that this activation strategy is critical to the occurrence of cyclization reactions.Control experiments showed that typical hydrogen-bonding catalysts were ineffective for this reaction,and the interaction between monodentate chalcogen-bonding donors or non-specific catalyst donors with aziridine was insufficient to produce catalytic activity.This study also proved the potential of chalcogen-bonding interactions in catalyzing chemical reactions,which provided a theoretical basis for the in-depth study of chalcogen-bonding interactions and broadened the space for future explorationPart 2.Chalcogen-bonding interactions catalyzed cycloaddition reactions of aziridines with alkynesBased on previous experimental investigations,chalcogen-bonding catalysis approach to cyclization of aziridines with nonactivated olefins was established.Experimental results revealed that the bidentate catalysts with confined binding distance enabling the simultaneous formation of double chalcogen-bonding interactions with the proper Lewis basic sites of aziridines generate catalytic capability.It is envisaged to further expand the activation mode and found that aziridine activated by this weak interaction can also react with alkynes to realize cyclization reaction,which can be used as a new method for preparing dihydropyrrole derivatives.Competition experiments have shown that the addition of Lewis bases can inhibit the cycloaddition reaction.Control experiments showed thatthe interaction between monodentate chalcogen-bonding donors with aziridine was insufficient to produce catalytic activity.This study realized the cyclization reaction by the weak interaction of chalcogen-bonding interactions instead of metal catalysis,and had the advantages of mild reaction conditions and simple operation.The synthesized dihydropyrrole derivatives had important research significance in the field of biomedicine,which also showed the application value of chalcogen-bonding interactions.