Palladium-Catalyzed [4+1] Dearomative Spiroannulation Reactions Of Phenolic Compounds

Spiro-ring skeletons have been widely found in natural products,pharmaceutical molecules and functional materials.Many spirocyclic ring skeletons which cannot be synthesized by traditional chemical methods can be successfully constructed by utilizing transition metal catalyzed dearomatization reactions of aromatic compounds.However,some disadvantages such as the complexity of synthesizing substrates,strong designability and single reaction type greatly limited the development of dearomatization reaction.In order to broaden the database of spirocyclic ring molecules,we successfully realized the dearomatizing[4+1]spiroannulation reaction of naphthol compounds via five-membered cyclopalladation strategy,which established a new method for the synthesis of new spirocyclic ring molecules,especially unsymmetrical spirofluorenes and spirocyclic[4.5]skeletons.The following three parts were mainly introduced in the paper:Chapter One briefly introduced the significance of constructing the spiral ring framework and pointed out the advantages of transition metal catalyzed aromatization of aromatic compounds.Moreover,the elaborate progress of transition metal catalyzed intramolecular and intermolecular dearomatization of aromatic compounds had been introduced.The strategy of utilizing five-membered cyclopalladation to efficiently and quickly construct spiral ring molecules was proposed.Chapter Two mainly reported that the[4+1]spiroannulation of o-aryl iodobenzene compounds and naphthol compounds were successfully realized by using C?sp²?-Pd^II-C?sp²?cyclopalladation strategy.Meanwhile series of unsymmetric spirofluorene skeletons had been constructed efficiently by using this strategy with high chemoselectivity and excellent functional group compatibility.Using this method,a simple and efficient synthesis of 7-hydroxyl-1-carbon coumarin had been realized while preliminary studies of the spectral properties and pK_a of 7-hydroxy-1-carbon coumarin had been conducted.This method could be used to enrich the database of 1-carbon coumarins by adjusting and modifying the framework structure of molecular.Chapter Three mainly reported that the first C?sp³?-H activation/dearomatization cooperative reaction transformation had been realized by using C?sp²?-Pd^II-C?sp³?five-membered cyclopalladation strategy.The activation of the inert C?sp³?-H bond,the formation of the C?sp²?-Pd^II-C?sp³?five-membered cyclopalladation intermediate and the dearomatization of naphthol compounds were realized in the one-step transformation.The method efficiently and rapidly constructed series of novel snail[4.5]skeleton molecules with high yield and wide range of substrates.This reaction not only realized the activation of the inert C?sp³?-H bond of o-tert-butyl iodobenzene compounds,but also activated the inert methoxy C-H bond which was more difficult to be activated under similar conditions.From this reaction the reactive transformation of two o-methoxy iodobenzene compounds had been realized which also laid a solid foundation for the further study of correlate work.