Studies On The Cyclization Reactions Of Propargyl-allenyl Isomerization

Propargyl-allenyl isomerization had attracted much attention by the organic community due to its atom-economic advantages and environmental benefits,which emerged wide range of applications in pharmacology,natural products and advanced materials.In particular,heteroatom-promoted propargyl-allenyl isomerization occupied an important position in organic synthesis.In this dissertation,the research background of the utilization of propargyl-allenyl isomerization reactions in cascade cyclization had been reviewed,and the details of my study were summarized as following:1)Rh(?)-catalyzed base assisted 1,5-H shift strategy for the construction of seven-membered ringsWe developed a sulfone promoted Rh(III)-catalyzed C-H activation for the synthesis of benzothiepine/thieno[2,3-b]thiepine sulfones,which relies on a sequence of Rh(?)-catalyzed C-H cleavage,1,5-H shift and intramolecular allene insertion.Deuterium shift experiment demonstrated that an intramolecular insertion had occurred,and the KIE study revealed that the C-H cleavage of arenes might be the turnover-limiting step.As a result of extremely readily accessible starting materials and convenient operation,this protocol should be an appealing strategy in organic synthesis.2)Base regulated propargyl-allenyl isomerization for the synthesis of polyfunctionalized 1,2-dihydrocyclobuta[b]naphthalene and 1,2-dihydroanthraceneOn the basis of propargyl-allenyl isomerisation,base regulated propargyl-allenyl isomerization had been realized by preparing the substrate which equipped with propargyl and acetylene allyl group.When TEA as base,1,2-dihydrocyclobuta[b]naphthalenes were afforded,including a series of 1,5-H shift,[2+2]cycloaddition and aromatization;When DBU as base,1,2-dihydroanthracenes were afforded via Bergman cyclization.The reaction was environmentally benign and metal/ligand-free.3)Regioselectivity synthesis of functional thiophenes/naphthalenes via propargyl-allenyl isomerizationWe developed a convenient method for the regioselectivity synthesis of functional thiophenes/naphthalenes via propargyl-allenyl isomerization.When methylthio group and propargyl group in cis,an efficient access to thiophenes was realized by an intramolecular nucleophilic attack of sulfur to the in situ generated electron-deficient allene moiety;When methylthio group and propargyl group in trans,highly functionalized naphthalenes were yielded by the process of propargyl-allenyl isomerization,electrocyclization and aromatization.The starting materials were readily accessible,and the reaction could be completed in one pot.4)Regioselectivity synthesis of functional thiophenes/naphthalenes via propargyl-allenyl isomerizationReactive carbonyl was prepared through TBD catalyzed formic acid ester compounds,acting as the surrogate of carbonyl.The carbonyl insertion reaction of propargyl substrates and aryl halides has been achieved also.Many substituents tolerate the reaction conditions and produce carbonyl compounds in moderate to good yields.