Rhodium-Catalyzed C-H Functionalization Of Indole And Azaindole Derivatives

Over the past decades,breakthrough progress has been made in the area of transition-metal-catalyzed C-H bond activation,which has emerged as a powerful tool in organic synthesis for the construction of complex molecules.In particular,rhodium-catalyzed C-H bond activation has attracted increasing attention in recent years owing to the high catalytic efficiency of the catalyst,broad substrate scope and excellent functional group tolerance.On the other hand,indole and azaindole derivatives are an important class of heterocycles widely occurred in biological active molecules and materials.As a result,the modification of these heterocycles has been a hot topic in recent synthetic organic chemistry.In this dissertation,we focused on the Rh-catalyzed direct C-H functionalization of 7-azaindoles and indoles.The main contents of this dissertation consist of the following five chapters.In chapter 1,the significance of C-H bond activation as well as typical reaction pathways for transition metal mediated C-H bond activation are described.The recent research progress on Rh-catalyzed C-H activation and functionalization has been briefly reviewed.Furthermore,the research objectives of this dissertation are presented.In chapter 2,a 7-azaindole directed protocol for the Csp2-H alkynylation of 7-azaindoles using y-substituted tert-propargyl alcohols as the alkynylating reagent under[Rh(COD)(OH)]2/Cu(OAc)2/AgOAc catalytic system has been developed.This protocol is compatible with wide substrate scope and various functional groups in moderate to good yields,especially the alkynylating reagent substrated with a bulk?-conjugate anthracene group can be also tolerated to this reaction.This alkynylation strategy provides a new approach for further modification of 7-azaindoles.In chapter 3,a rhodium(?)-catalyzed oxidative annulation of 7-azaindoles with internal alkynes involve double C-H activation process and subsequent roll-over C-H activation of the heterocycle ring to form diverse complex 7-azaindole derivatives have been successfully developed.A broad scope of 7-azaindoles and internal alkynes has been demonstrated and most of the examples gave moderate to excellent yields.H/D exchange and kinetic isotope effect experiments have been conducted for mechanistic studies.The cyclometallated intermediate has been isolated from the stoichiometric reaction and modeling reaction has been carried out to verify the proposed mechanism.In chapter 4,an effective rhodium(?)-catalyzed regioselective C-H alkenylation of indoles with electron-rich vinyl acetate as the vinyl source has been developed to construct diverse ?-conjugate(E)-1,2-bis(1-(pyridin-2-yl)-1 H-indol-2-yl)ethane derivatives via cascade C2 alkenylation of two indole molecules.Cross coupling products can be obtained in moderate yield when two different indole substrates were used in the reaction.The broad substrate scope and removable directing group as well as the accessible gram scalable reaction of this strategy render the potential synthetic utility for the protocol in organic synthesis.In chapter 5,the research work of this dissertation was summarized.