Three-component Reactions Based On Oxonium Ylides Trapped By Dicobalt Hexacarbonyl-complexed Propargylic Alcohols Or Allylpalladium Complexes

Multicomponent reaction has been widely used in drug discover and the synthesis of nature products,because it can construct complicate molecules with high atom economy.Our group make great efforts to research the multicomponent reaction of trapping ylide intermediates or zwitterionic intermediates.Developing new electrophiles for trapping ylide intermediates is one of the most important issues of this kind of reaction.Dual catalysis was a new strategy developed in recent years.In dual catalysis,two different catalysts were put in one pot and they can activate different reactants.The strategy of dual catalysis can lower the activation energy effectively,especially in multicomponent reactions.In this paper,we have developed two new methods about using alkyl electrophile to trap oxonium ylides.With the introduction of bimetal dual catalysis strategy,we solve the problem that alkyl electrophile cannot trap ylide intermediate effectively because of its high energy barrier and low reaction speed.This new method broadens the scope of the electrophiles in this kind of reaction ant it can construct complicate molecules with alkyne or alkene substitutes.In Chapter 2,we developed a new multicomponent reaction,based on the Nicholas reaction,in which the oxonium ylides were trapped by propargyl carbon cation in the catalysis of Rh₂（OAc）₄ and Ag BF₄.We use carbon cation,which is generated from dicobalt hexacarbonyl-complexed propargylic alcohols in situ,to trap oxonium ylides generated from 3-diazoindolin-2-one and benzyl alcohol.We use this reaction to get 3,3’-bisubstitute indolin-2-one with a terminal alkyne substitute in good yields and regioselectivities.It is the first time that we have achieved a multicomponent reaction by using carbon cation to trap oxonium ylides in the bimetal dual catalysis strategy.We solved a problem about the carbon cation to trap the ylide intermediate because of its low stability,high energy barrier and low reaction speed.We also broaden the substrate scope of the Nicholas reaction.In Chapter 3,we used bimetal dual catalysis strategy again.We used allylpalladium complexes to trap oxonium ylide in a multicomponent reaction.We used allylpalladium complexes generated from allyl methyl carbonate in situ to trap the oxonium ylide generated from 2-diazo-1-phenylethan-1-one and alkylol.We used this method to get 1-phenylpent-4-en-1-one in good yields and regioselectivities.We solved a problem about the allylpalladium complexes could not be used as an electrophile to trap oxonium ylide in intermolecular multicomponent reaction because of its low reaction speed and its incompatibility reaction condition.It is the first time that we have achieved a multicomponent reaction by using allylpalladium complexes as the electrophile to trap oxonium ylides in the bimetal dual catalysis strategy.This method provides a new choice of electrophile in the reaction of trapping ylide intermediate.And in this reaction,we successfully used catalytic amount of transition metals to activate alkyl electrophiles.This would increase the atom economy of the reaction.