Gold-catalyzed Tandem Reactions Of Alkynes For The Synthesis Of Heterocycles And Polycyclic Compounds

Homogeneous gold catalysis has become one of the most active research fields in organic chemistry in the past decade due to its high catalytic activities,benign reaction conditions and good tolerance of various functional groups.Based on these specific features,significant methodologies have been developed and many of them have been successfully applied into the synthesis of numerous natural products and biologically active molecules.In view of the unique activity of gold catalyst and the high efficiency and atom ecomomic of tandem reactions,the central theme of this project is focus on the development of gold-catalyzed tandem cyclization for the construction of highly functionalized heterocycles and polycyclic compounds and extend the new solutions to unsolved problems in synthetic organic chemistry.This dissertation is divided into the following sections mainly:In the first part,the development of homogeneous gold catalysis and tandem reactions are briefly introduced.Importantly,the strategy of tandem annulations for the construction of heterocycles and polycyclic compounds was summarized on the basis of literature review.On the basis of above mentioned background,the main research ideas for designing of the thesis are discussed.In the second part,the gold-catalyzed tandem alkyne 5-endo-dig anti-Markovnikov cycloisomerization/oxidation reactions was studied.We have developed a flexible and general solution for the synthesis of various y-lactones and y-lactams via a tandem gold-catalyzed cycloisomerization and in situ regioselective m-CPBA oxidation sequence from the corresponding readily available precursors.In the third part,the gold-catalyzed tandem cycloisomerization-halogenation of chiral homopropargyl sulfonamides was studied.Two new gold-catalyzed tandem cycloisomerization-halogenation reactions of chiral homopropargyl sulfonamides have been developed.Various enantioenriched 3,3-diiodopyrrolidin-2-ols and 3-fluoropyrrolidin-2-ols were obtained in moderate-to-good yields with excellent enantio-and diastereoselectivity.In the fourth part,gold-catalyzed tandem alkyne 6-exo-dig cycloisomerization/aromatization was studied.We have developed two economic and efficient methods via gold-catalyzed alkyne 6-exo-dig cycloisomerization/aromatization reactions,leading to the concise synthesis of versatile the polycyclic aromatic hydrocarbons(PAH)derivatives in moderate to good yields.In the fifth part,gold-catalyzed alkyne oxidation/X-H(X=N,O)insertion was studied.We have developed three efficient and practical solutions for the synthesis of various pyrrolidin-3-ones,3-oxyindoles and 3-coumaranones through gold-catalyzed tandem alkyne oxidation/X-H insertion procedure.In the sixth part,gold-catalyzed alkyne amination initiated tandem reactions was studied.We have developed gold-catalyzed intermolecular ynamide amination-initiated formal[3+2]annulation,[4+2]annulation,aza-Nazarov cyclization,C-H functionalization and cyclopropanation via key a-imino gold carbenes,leading to the efficient synthesis of versatile N-containing molecules environmentally friendly,such as 2-aminoindoles,3-amino-?-carbolines,2-aminopyrroles,2-aza-1,3-butadienes and 3-azabicyclo[3.1.0]hexane in generally good to excellent yields from readily available precursors.In addition,a mechanistic rationale for the observed highly regioselectivity is also strongly supported by DFT computations.