Study On The Formation Of CC Bonds Catalyzed By DNA In Water Phase

Transition metal catalysis is one of the important strategy of constructing C-C bonds.In recent years,much attention has been paid to transitional metal catalyzed organic reaction in water due to the adoption of eco-friendly solvent water for minimizing environmental pollution generated by chemistry industry.Therefore,it is of great scientific significance to carry out relevant research for transitional metal catalysis in water medium.The addition of surfactant to increase the substrate and catalyst molarity is currently a relatively effective strategy to improve the efficiency of the aqueous phase reaction.However,conventional surfactant have the disadvantages include large quantity needed and causing environments issues.Therefore,it is of great urgency to find new ideas for the construction of C-C bonds catalyzed by transitional metals in water medium.DNA is widely known as a biological macro-molecule related with genetic function.In recent years,DNA has also begun to be applied in fields such as nanotechnology and catalysis.In chapter 1,the structural characteristics of DNA was summarized first,and then the objective critics of the latest advances for the DNA catalysis on C-C bonds construction was carried out from two aspects,the acceleration effect and asymmetric catalysis on C-C bonds formation.Literature surveys show that the current DNA catalysis is still in its infancy mainly due to few catalytic reaction types developed and waste of DNA chiral structures.DNA is soluble in water,has a hydrophobic region inside the double-helix structure,and permits to construct plentiful chiral environment.Taken all these characteristic together,a good structural foundation has been laid for the construction of C-C bonds(carbon chiral centers)through the aqueous phase transition metal catalytic reaction.In order to further develop DNA catalytic function and solve the major problems in present DNA catalysis,two piece of work has been carried out in this thesis:(1)study on DNA accelerated Sonogashira coupling reaction in water medium;(2)study on asymmetric Michael addition based on oligomeric double-strand DNA hybrid catalyst.The specific research content is as following:(1)An efficient approach for the synthesis of ynone compounds via DNA-accelerated palladium-copper catalyzed aqueous Sonogashira coupling reaction was developed.Through the characterization of the Pd-Cu catalyst,the interaction study between DNA as well as substrates and catalyst,the mechanism of DNA acceleration effect was proposed-DNA plays as a role of multifunctional surfactant during the reaction:DNA enhances the substrates and catalyst's molarity through intercalation mode,meanwhile stablize Cu(I)and promote the formation of Pd(0)during the reaction.(2)A method for the synthesis a series of chiral Michael addition adducts,with ee value up to 95%,asymmetrically catalyzed by a 9-mer ds-DNA based hybrid catalyst has been developed,maximizes the utilization of the DNA chiral structure.Circular dichroism studies show that maintaining B-type secondary structure for oligomeric ds-DNA.