Study On The Catalytic Reactions Of Alkenes,Electron-Deficient Cyclopropanes And Propargylic Alcohols Enabled By Chalcogen-Bonding Interactions

Chalcogen bonding interaction describes a weak interaction between a chalcogen atom in a molecular entity and an electron donor.Chalcogen bonding interactions play an important role in the regulation of protein conformation,ion recognition,drug design and material chemistry.However,the use of chalcogen bonding interactions to catalyze chemical reactions is currently in its infancy.These chalcogen bonding interactions are highly directional and their strength is adjustable,which provide a good basis to carry out chalcogen bonding catalysis.The activation of alkenes,electron-deficient cyclopropanes and propargyl alcohols by weak chacogen bonding interactions is yet to be investigated.In this thesis,highly active chalcogen bonding catalysts were synthesized to promote the coupling and cyclization reactions of alkenes by Se…πinteraction mode,while the Cloke--Wilson rearrangement reaction of electron-deficient cyclopropanes and the cyclization and coupling reaction of propargyl alcohols were achieved by Se…O interaction mode.Part I:Study on cyclization and coupling reactions of alkenes catalyzed by chalcogen bonding interactionsRelying on the electron-donating ability of heteroatoms,chalcogen bonding interactions can activate several functional groups containing heteroatoms,such as carbonyl,imine,and nitro,etc.However,the use of weak interactions to activate hydrocarbon compounds is generally considered as a bottleneck problem in this field.For example,how to activate alkenes by weak interactions is an unresolved challenge.In this thesis,highly active chalcogen bonding catalysts were developed for the activation of alkenes to achieve cyclization and coupling reactions of alkenes,intermolecular enyen cyclization reactions and triple alkenes coupling reactions.The experimental results showed that Se…π weak interactions can be more efficient than Rh in catalyzing intermolecular enyne cyclization reactions,thus enabling shifting the catalysis mode from Rh to Se…π weak interaction catalysis.In addition,the Se…π weak interaction can catalyze the triple alkene coupling reactions by modulating the reactivity of the reaction intermediates.which otherwise are inaccessible by conventional strong Lewis acid approach.Based on the analysis of the interactions as shown in the crystal structure of catalyst and the results indicated by NMR experiments,this thesis proposesd a Se…Se interaction assisted Se…π catalysis model for the activation of olefins,which provides a new insight on the activation of alkenes.Part II:Study on the Cloke-Wilson rearrangement reactions catalyzed by chalcogen bonding interactionsThe Cloke-Wilson rearrangement reaction is an important method for the construction of heterocyclic compounds,and strong Lewis acids were often used as catalyst/promoter in these reaction processes.The development of a distinct catalysis approach that employs weak interaction as a driving force to promote the Cloke-Wilson rearrangement yet remains an unresolved problem.This thesis established a new approach to the Cloke-Wilson rearrangement reactions which were facilitated by double Se…O interactions,thus realizing a concise and efficient synthesis of dihydrofuran derivatives.The reaction mechanism was investigated by NMR and control experiments.This research work expands the reaction scope catalyzed by chalcogen bonding interactions.Part III:Study on cyclization and coupling reactions of propargylic alcohols catalyzed by chalcogen bonding interactionsPropargyl alcohols are a class of compounds with both alkynyl and hydroxyl functional groups,and they are widely used as key reactants in organic synthesis.Despite significant advances in the activation of propargylic alcohols,a weak interaction approach remains unexplored.This thesis developed the cyclization and coupling reactions of propargyl alcohols catalyzed by Se…O interactions.The reactions were carried out using propargyl alcohols and simple alkenes as raw materials to give polycyclic indene derivatives in moderate yields.Notably,only 0.1 mol%catalyst loading was required to achieve these cyclization reactions.It was found that this catalysis approach could be expanded to the coupling reactions of propargylic alcohols and alkenes as well as the Meyer-Schuster reactions.This work expands the types of substrates that were activated by chalcogen bonding interactions,and provides a different approach to catalyzing propargylic alcohols mediated reactions,...