Study On The Construction Of Hexacyclic-1-Naphthols,Oximes And 1,2-Naphthoquinone Via Yne-Allenone

Cycloaddition reactions are a type of transformations in which two or more unsaturated molecules or different reactive sites from the same molecule are combined to form cyclic adducts by matching frontier molecular orbitals,and they are the most commonly used methods to construct cyclic skeletons in organic synthesis.Such reactions could use simple starting materials to synthesize carbocyclic or heterocyclic molecular skeletons with different structures and have the advantages of high selectivity,atom economy and high efficiency as well as practicality.So far,cycloaddition reactions have been rapidly developed,mainly including[2+2],[3+2],[4+2]etc.,most of which require transition metal catalysts,Lewis acid catalysts,heat or/and light.Therefore,continued development of new cycloaddition reactions for the construction of cyclic molecules with potential biological activity still has important research significance and academic value.The key to establish cycloaddition reaction is to make the synergistic participation of multiple active sites from synthetic building blocks,leading to synthesize the target cyclic compounds in a simple and efficient manner.As a result,the key to develop cycloaddition reaction strategies is to search substrates with multiple reactive sites.Yne-allenones bearing three reactive sites such as a carbonyl,an alkyne and an allenes are often used as effective synthons for radical chemistry,cycloadditions and nucleophilic addition reactions.In this thesis,yne-allenones were used as the key starting material to establish three new types of reactions which involved visible-light catalysis,Lewis acid catalysis and radical-induced tranforamtions,respectively,leading to the formation of 78 examples of hexacyclic 1-naphthols,xanthenes and 1,2-naphthoquinones.The research content is mainly divided into the following three parts:The first part mainly summarizes the reaction types and recent research progress of cycloaddition reactions.Based on the the literature overview,the research content and significance of this thesis were proposed.The second part developed a new type of photocatalytic double[2+2]cycloaddition relay reaction of yne-allenones.By using the characteristic of the self-photosensitivity of yne-allenones,visible light catalyzed reaction enabled the double[2+2]cycloaddition relay to a series of hexacyclic 1-naphthol derivatives with good yield and high diastereoselectivity without other photosensitizers or catalsyts,thereby realizeing the carbon-carbon triple bond cleavage and recombination of yne-allenones.Sereval control experiments indicated that the prodcol involves energy transfer.Furthermore,this approach features mild reaction conditions,100%atom utilization and high cyclization efficiency.In order to expand the scope of application of the method,the reaction of hexacyclic 1-naphthols with dimethoxy（methyl）silane in the presence of sodium methoxide by using Cu CN and1,1-Bis（diphenylphosphino）ferrocene（DPPF）as catalytic system gave the reduced product with a high yield.According to literature reports and experimental results,a feasible mechanism is proposed,which involves twice double[2+2]cycloadditions,four-membered ring opening and recyclization cascade.The third part introduces a BF₃·Et₂O-catalyzed[2+2]cycloaddition relay of yne-allenones and 1-alkynyl-2-naphthols.By using DCE as the solvent and BF₃·Et₂O as the Lewis acid catalyst,the reaction was carried out at 50°C under argon conditions,leading to the formation of a series of rotationally hindered fused xanthenes with good yields.The protocol also features mild reaction conditions,high stereoselectivity and high annulation efficiency as well as high functional group tolerance without additives and metal catalysts,thereby making the workup simple and convenient.According to literature survey and experimental results,a reasonable mechanism is proposed,which involves a successive sequence of double[2+2]cycloaddition relay,nucleophilic addition and proton transfer as well as aldol condensation.The fourth part describes a new[2+2]cycloaddition/radical-induced 1,4-addition cascade of yne-allenones and.Starting from yne-allenones and arylsulfinic acids as starting materials,tert-butyl hydroperoxide（TBHP）/diphenyl diselenide mediated reaction in1,4-dioxane delivered a series of sulfonyl substituted 1,2-naphthoquinones with good yields,thereby enriching the types of sulfone compounds.Compared with the literature reports that diphenyl diselenide serves as a free radical donor,herein,diphenyl diselenide was used as a radical initiator to trigger the generation of sulfonyl radcial and TBHP was used as an oxygen source,which made the the effective construction of C-C bonds and C-S bonds.This approach has the advantages of wide substrates scope,good yields and high regioselectivity thus offering a new synthetic method for the synthesis of 1,2-naphthoquinones.The fifth part belongs to the experimental part,where the synthesitic methods for all these compounds were described.The sixth part belongs to the characterization data of all above compounds.In summary,in this thesis,yne-allenones were exploited as the key substrates to construct hexacyclic 1-naphthol,xanthene and 1,2-naphthoquinone scaffolds through different cycloaddition reactions,A total of 78 compounds were synthesized with good to excellent yields.In addition,the structures of all these products have been confirmed by NMR,MS,IR data,etc.Some of them have been confirmed by X-ray single crystal diffraction analysis.The radical intermediates involved in the mechanism were detected by LC-MS.