Study On Selective Conversion Of Olefins To Polysubstituted Olefins Or Indanes Catalyzed By Acidic Ionic Liquids

Polysubstituted olefins and indanes as important organic blocks are widely used in medicine,functional materials,and other fields.Therefore,cost-effective methods for synthesizing the above compounds have always been a research hotspot in this field.Among them,ether,as a widely used compound,is often used for the protection of hydroxyl groups,and has always been an important raw material in organic synthesis,and has great potential application in the construction of carbon-carbon bonds and carbon-hetero bonds.Ionic liquids are salts composed of anions and cations,which have the characteristics of difficult volatility,high boiling point and low toxicity and so on.And by regulating the composition of anions and cations,ionic liquids can have different functions,and have great application prospects in the fields of catalysis,extraction,electrochemistry,lubrication and so on.By introducing special acid groups,the catalytic properties of ionic liquids can be tuned to obtain acidfunctionalized ionic liquids.Compared with traditional acid catalysts,acidic ionic liquids have the characteristics of environmental friendliness,good stability,low volatility,easy separation and recycling et al.More importantly,due to the special ion pair and acid functional group,it can form a variety of intermolecular forces such as hydrogen bonding effect to activate the substrate.Based on this,acidic ionic liquids selectively catalyzed systems for the conversion of benzyl ether and olefins to construct new carbon-carbon bonds have been developed in the dissertation.Among them,polysubstituted olefins were synthesized from benzyl ether and aryl substituted olefins catalyzed by sulfonylthiomorpholine-1,1-dioxide ionic liquid[Bs Me(dio)TMP][OTf].The cyclization reaction of benzyl ether and endoene to obtain indane compounds was selectively realized with sulfonic acid functionalized pyridine ionic liquid[BsPy][OTf] as the catalyst.The contents are as follows:(1)Using sulfonic acid functionalized thiomorpholine-1,1-dioxide ionic liquid[Bs Me(dio)TMP][OTf] as the catalyst and dimethyl carbonate(DMC)as the green solvent,a series of polysubstituted olefins containing aryl groups were selectively obtained from diphenylether derivatives and aromatic olefins to construct new C-C bond with up to 88%yield.The results showed that the system had the advantages of high catalytic efficiency,recoverable catalyst,and no reduction in the yield of gram-scale reaction.The results of density functional theory(DFT)show that ionic liquids can activate the C-O bonds of substrate ethers through hydrogen bonding and make them break to form carbocation ions,and this process is a rate-determining step of the reaction.The biphenyl ring structure of diphenylmethyl methyl ether has a π-π stacking effect,which can effectively reduce the reaction energy barrier.[Bs Me(dio)TMP][OTf] ion pairs can activate substrates and have similar barriers indicating that the anions and cations show synergistic catalytic effects in this reaction.(2)Based on the above synthesis of polysubstituted olefin catalyzed by acidic ionic liquid,it was found that when aryl substituted internal olefin was used as raw material,a small amount of indane was also generated in addition to the main product.Screening of a serious of acidic ionic liquids,it was found that sulfonic acid functionalized pyridine ionic liquid [BsPy][OTf] could efficiently realize the selective cyclization reaction of diphenyl ether derivatives and aryl-substituted internal olefins to generate a series of indane compounds with up to 95% yield.The developed catalytic system exhibited high efficiency,and the catalyst was easy to separate and recover.And the reaction performed well in the gram-scale reaction.The acidity of ionic liquids was tested by UV/VIS spectrophotometer,and the results showed that high acidity was beneficial to improve the selectivity of indane products.DFT results showed that the substrate and catalyst had hydrogen bonding and π-πstacking.Product selectivity was attributed to the competition process between thermodynamic product indane and kinetic product polysubstituted olefin,and the selectivity of thermodynamic product indane could be improved by extending the time.