Transition-Metal Catalyzed Organic Transformations Of Arynes

Arynes are strained alkynes,which have been widely used in various carbon-carbon bond and carbon-heteroatom bond synthesis.They have high ring strain energy(63 kcal mol~-),low lying LUMOs and the energy gap between the HOMO and LUMO is very low.Therefore,aryne can participate in the cycloaddition reaction,the ? bond insertion reaction,and also can be used as electrophilic reagent to participate in nucleophilic addition reaction.In addition,the triple bond in aryne can form complexes with transition metals,and can participate in a series of novel reactions.In this thesis,arynes and cycloalkynes,which are very reactive strained species,are used for the first time to participate in palladium-catalyzed C-H/N-H activation process to construct heterocycles.Besides,a copper-catalyzed three-component coupling reaction of in situ formed arynes,terminal alkynes,and benzenefulfonothioates is described.The thesis has three parts:In the first part,strained alkynes include arynes and cyclooctynes reacted with N-methoxyamides through palladium-catalyzed C-H/N-H activation for the first time.A variety of important N-heterocycles such as phenanthridinones and isoquinolones were constructed in one step with high efficiency.Making the challenging C-H activation and reactive transient aryne intermediate compatible is the determinant success of this reaction.This new methodology represents a new direction on transition metal participated benzyne chemistry and also C-H functionalization.In the second part,an unprecedented palladium-catalyzed oxidative annulation of acrylamides with benzyne precursors has been successfully developed.By using this mild N-H activation/C-H activation,a wide variety of quinolinones were conveniently prepared in one step with high efficiency,which cannot easily be accessed by other methods.Using the reactive transient arynes to realize challenging C-H activation under mild conditions represents a new direction on C-H functionalization.In the third part,a copper-catalyzed three-component coupling reaction of in situ formed arynes,terminal alkynes,and benzenefulfonothioates is described.This nucelophilic attack and electriphilc trap reaction involves efficient C-C and Csp~2-S bond formation in one-pot.A wide variety of o-alkynyl aryl sulfides were modularly constructed from readily available starting materials and various functional groups were tolerated under these mild conditions.We envision that the reaction mode outlined herein will have potential applications in other significant synthetic transformations.