Transition Metal-Catalyzed C-H Functionalization For The Synthesis Of Indoles And Styrene Derivatives

Transition metal-catalyzed C-H functionalization has emerged as a powerful tool in the synthesis of drugs,natural products and materials.This protocol features broad functional group tolerance,excellent selectivity,readily available starting materials and in a step and atom-economical fashion.In recent years,the transition metal-catalyzed C-H functionalization reactions for the construction of nitrogen-containing heterocyclic skeletons and functionalized olefins have greated enriched the diversity of products,and provided a noval,economical and environmentally friendly synthetic route for the preparation of these compounds.Notably,the indoles and aryl ethylenes are important organic intermediates which were widely used in pharmaceuticals,pesticides,dyes and materials.In this thesis,we focus our attention on transition metal-catalyzed C-H the construction of indoles by transition metal-catalyzed C-H cyclizations and aryl ethylenes by alkenylation reactions.The thesis consists four chapters as follows:In chapter 1,we briefly outlined the concept of C-H functionalization,and summarized the recent progress on the the synthesis of indoles and styrene derivatives through chelation-assisted transition metal-catalyzed C-H functionalization Furthermore,we also discussed the purpose and design ideas of this project.In chapter 2,we described a convenient and effective method of amide-directed ruthenium-catalyzed C-H annulations using vinylene carbonate as oxidizing acetylene surrogate.The reaction was carried out under argon atmosphere with 5 mol%Ru（p-cymene）Cl₂,20 mol%Ag Sb F₆,10 mol%Zn（OAc）₂ in ethylene glycol dimethyl ether for 24 hours at 80 ^oC.This method is scalable with 29 cases of substrate range and compatible with a wide range of functional groups.A preliminary mechanistic study was also investigated through a series of control experiments.In addition,the directing group could be easily removed,and affording the corresponding NH indole.This method provides a simple,economical and green synthetic route for the synthesis of indoles.In chapter 3,we discussed a Rh（Ⅲ）-catalyzed direct alkenylation of arenes with readily available vinyltrifluoroborate to direct access to functionalized styrenes.The reaction conditions were mild under argon atmosphere with 5 mol%Rh Cl₂Cp*,2.0equiv.Cu（OAc）₂ for 14 h at 80 ^oC in dichloromethane;there were 33 examples of substrate expansion with moderate to good yields and good selectivity.A series of controlled experiments were designed to investigate the mechanism.Importantly,the thus-obtained functionalized styrene derivatives could be further transformed into N-acetylaniline and heterocyclic compounds such as indole and thiazineIn chapter 4,we summarized the all the research projects of this thesis and also found some limitations of the developed catalytic system.We hoped that all these problems could be successfully solved in future.