| In the past ten years,transition-metal-catalyzed direct functionalization of C-H bonds has emerged as a powerful strategy in the construction of organic building blocks of complex structures.Because of the unique structure and coordination properties of Rh（Ⅲ）complex,the catalytic system is generally highly efficient,highly stable and good selective.Compared with other transition metals,Rh（Ⅲ）complex has unique advantages in the research of heterocycle synthesis.Meanwhile,diazo reagents have been demonstrated as active carbene precursors as coupling reagents in Rh（Ⅲ）-catalyzed arene C-H activation.According to the nature of the directing group in the arene,both simple alkylation and cascade cyclization products have been obtained.On the other hand,functionalization of the extremely inert C-F bond has emerged as one of the great challenging research topics in the organic chemistry in the recent years.In this paper,Rh（Ⅲ）-catalyzed C-H activation,carbene insertion and C-F cleavage were studied,based on comprehensive summary of Rh（Ⅲ）-catalyzed various C-H activation and Rhcatalyzed C-F bond cleavage.The results are as following:On the basis of rational design and extensive screening,diazo reagents bearing an orthofluorine group were designed as a multifunctional carbene precursor for cascade cyclization via Rh（Ⅲ）-catalyzed C（sp2）-H activation of N-pyrimidylindoles,N-pyrimidylisoquinolinone,2Phenylpyridine and uncatalyzed intramolecular nucleophilic aromatic substitution.Moreover,C（sp3）-H activation of 8-Methylquinoline has been achieved,which further broadened the range of substrates.The reactions are generally efficient and proceeded with high functional group compatibility.Alkenylated key intermediate has been isolated to explain the mechanism in details.This methodology helps the efficient direct functionalization of C-H bonds and provides an unprecedented strategy for the construction of value-added heterocycle chromone derivatives. |
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