Bifunctionalization Of Cyclopalladium Intermediates Formed By Palladium(0)-Catalyzed C-H Activation

As a step-and atom-economical manner to build a variety of organic scaffolds,transition-metal catalyzed C-H bond functionalization has been rapidly developed since the beginning of the twenty-first century.Those conversions are so attractive and powerful that they have changed our perceptions of organic chemistry because a C-H bond now can be considered as a functional group.However,a molecule often contains a large number of different types of C-H bonds,so it is particularly important to selectively activate a C-H bond at a specific position.To address these issues,a directing group strategy has been introduced,However,it is often very complicated to preinstalling directing groups.On the other hand,the exponential developement of Pd(0)-catalyzed C-H activation seems to be a very promising alternative and could handle above problems.Based on this,we researched Pd(0)-catalyzed C(sp3)-H carbonylation reaction and Pd(0)-catalyzed C(sp2)-H silylation reaction.This dissertation mainly includes the following sections.Chapter 1:Research backgroundWe briefly describe the history,progress and trends of Pd(0)-catalyzed C-H bond activation.At the same time,the role of the five-membered palladium intermediate in the selective activation of the target C-H bond and the phenomenon of palladium migration were also systematically described.Chapter 2:Pd(0)-catalyzed C(sp3)-H carbonylationWe developed a Pd(0)-catalyzed C(sp3)-H carbonylation reaction to construct indanone derivatives.Inner mechanism study reveals that the five-membered palladacycle is the key intermediate and insertion of carbon monoxide takes place at the last step.Chapter 3:Pd(0)-catalyzed C(sp2)-H silylation reactionA Pd(0)-catalyzed sequential three-component reaction has been developed.The palladacycles,generated through cascade reactions of aryl halides and alkynes,are the key intermediates and react with hexamethyldisilane to form disilylated products.