Study On The Gold-Catalyzed Cycloaddition Reaction Involving Gold-Containing All Carbon Dipoles

Although cycloaddition reactions catalyzed by transition metals have been known since the mid-20th century,most cycloaddition reactions catalyzed by transition metals have involved the use of rhodium,ruthenium,cobalt,nickel or palladium catalysts.In recent years,gold complexes have also become excellent catalysts for new cycloaddition reactions,providing new methods to promote the formation of intermediates and modulate their reactivity to participate in the cyclization reaction.In view of the frequent occurrence of furan skeleton in many natural products,pharmaceutical molecules and materials,the synthesis of furan compounds under gold-catalysis has gradually become a rapidly expanding area.In this paper,the cycloisomerizations/ring-opening reaction of allenyl ketones bearing a cyclopropane forms the new all carbon 1,4-dipoles under gold(?)catalysis,and their efficient cyclizations with other suitable partners to afford polysubstituted fused furan compounds is disclosed.The main part of the thesis is divided into the following two parts:The first part mainly introduces the formal[4+3]cycloaddition reaction of allenyl ketones containing a cyclopropyl moiety and nitrone with the promotion of gold catalysts.By choosing suitable ligand-directed gold catalysts,two types of gold-containing all-carbon 1,4-dipoles could be generated selectively from the gold(?)-catalyzed cycloisomerizations of allenyl ketones bearing a cyclopropyl moiety,which undergo cycloadditions with nitrones to produce two regiomers of furan-condensed N,O-seven-membered rings in moderate to excellent yields highly selectively.The second part mainly introduces the formal higher-order[8+4]cycloaddition of gold-containing 1,4-all-carbon dipoles with tropone.Under mild conditions,this method delivered structurally complex furan-fused tricycles in generally moderate to high yields under mild conditions.