Research On Functionalization And Asymmetric Reaction Of Alkynes Initiated By Nucleopalladation

Alkynes constitue a very important class of raw materials derived from petrochemical industry in the history of human development, which could directly or indierectly influence the economic development of a country and life level of people. Meanwhile,owing to possess an active carbon-carbon triple bond, alkynes also have been promoting the development of organic synthesis. Throughout the development history of organic synthesis, alkynes have been playing pivotal roles. Particularly in the past decades, alkyne chemistry has experienced a rapid development not only due to its unique properties applied in biochemistry and material sciences, but also its capabilities used as useful synthons for further transformation into various functional groups,providing more possibilities in modern medicine syntheses. Hence, the utilization of facile and straightforward methods to convert alkynes into complex polyfunctional organic molecules is inevitable,in modern synthetic organic chemistry,one of the most hottest research topics.All along, transition metal-catalyzed alkyne functionalization is one of important methods for alkyne transformations. Among them, the researchs on palladium-catalyzed reactions are relatively detailed and systematical. For example, the nucleopalladation of alkynes is to apply the coordination of C-C triple bond to Pd(II), followed by a cis or syn addition under the interaction of different nucleophiles, affording a relatively stable alkenyl palladium species, which could subsequently undergo a series of tandem reactions including protonation, C-C double bond insertion and etc.On the basis of the above-described background, the research of this thesis has systematically investigated the nucleopalladation-initiated alkyne functionalizations, and realized the asymmetric synthesis of the correspongding reactions. The research contents consist of following three sections:In chapter two, the research is about the chloropalladation-initiated carbocyclization between alkynes and alkenes. The cyclic esters/ethers were afforded at room temperature through the reactions of alkynoic acids or alkynols with terminal alkenes by using Pd Cl2 as the catalyst, Cu Cl2 as the additive and acetonitrile as the solvent, respectively. The reaction has the advantages of mild conditions, broad substrate scope, high product yields and regioselectivity.In chapter three, we studied the chloropalladation-initiated asymmetric carboesterification reaction between alkynes and alkenes. It is the first time to employ chiral diamine auxiliary to realize such a reaction. We have designed the substrates linked with a chiral auxiliary, which then reacted with the terminal alkenes, the enantioselectivity of the products were obtained with up to 91% ee value. Moreover, the auxiliary could detach during the course of the reaction, and its configuration is retained.In chapter four, we have studied the amide oxygen-assisted palladium-catalyzed hydration reaction of alkynes. By employing amide group containing alkynes,the reaction generates a N,O-containing heterocyclic intermediate via an oxopalladation process. The intermediate undergoes a ring-opening reaction to afford the hydration product under acidic conditions. In comparison with other hydration reactions, this synthetic method has the merits of good functional tolerance, exclusive selectivity and mild conditions.