高价碘试剂诱导的官能化碳环化合物的合成研究

Electrophilic cyclization is the cyclization reactions of unsaturated compounds initiated by electrophiles. Due to the step-economy and high efficiency, it plays important role in the construction of many cyclic scaffolds, especially in the synthesis of heterocycles. However, the application of electrophilic cyclization in carbocycles is limited because of the weak nucleophility of carbon centre. The efficient carbocyclization of this mode is narrowly initiated by a few electrophiles like H+, Lewis acid, halogen,or organochalcogen derivatives and suitable on carbon centre neighboured by electron-withdrawn group or carbon centres of alkene or aryl moiety. Therefore the substrates are very limited and the resulting products are hard to be modified..This proposal is focused on the synthesis of functionalized carbocycles with hypervalent iodanes. The use of hypervalent iodanes to initiate the carbocyclization reactions of alkylated substrates through forming C-C bonds on C-H bonds of alkyl chain as the key step. This strategy could widen the electrophilic carbocyclization to simple alkyl substrates. Moreover, based on the functionality of hypervalent iodanes, different functional groups could be directed or post-induced on the resulting products. So the project will be greatly efficient on the synthesis of functionalized carbocycles.

亲电环化反应是不饱和底物在亲电试剂的作用下发生环化从而得到环状化合物。因其步骤经济、反应高效，在环的合成尤其杂环合成方面发挥了重大作用。由于碳原子中心较弱的亲核性，亲电试剂诱导的碳环化反应难度相对较大。一般用质子酸、氯、氯代硫醚等基团来诱导碳环化反应，碳环化反应的位点通常是带有邻位强拉电子基团的碳中心或是容易被亲电取代的烯键、苯环等，反应底物局限，进一步官能化难度大。.本项目提出利用高价碘试剂作为亲电试剂，与烷基取代的底物（如烯烃、炔烃等）作用生成的高活性中间体，诱导惰性烷基C-H键形成C-C键，发生碳环化反应，从而在烷基取代底物的直接碳环化反应领域取得更多突破。利用高价碘可以直接引入或者后修饰引入碳合成子、卤素、三氟甲基、叠氮甚至氰基等官能团，非常适于官能化碳环的合成。

亲电环化反应是不饱和底物在亲电试剂的作用下发生环化从而得到环状化合物。因其步骤经济、反应高效，在环的合成尤其杂环合成方面发挥了重大作用。由于碳原子中心较弱的亲核性，亲电试剂诱导的碳环化反应难度相对较大。本项目利用高价碘试剂作为亲电试剂，与烷基取代的底物（如烯烃、炔烃等）作用生成的高活性中间体，诱导惰性烷基C-H键形成C-C键，发生碳环化反应，从而在烷基取代底物的直接碳环化反应领域取得多项成果。利用高价碘可以直接引入或者后修饰引入三氟甲基等官能团，非常适于官能化碳环的合成。

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