| Indoles and their derivatives are ubiquitous structural moieties widely found in nature products,biologically and pharmacologically active molecules.The highly chemical-and regioselective synthesis of diversely functionalized indoles has always been a research hotspot in the field of organic synthesis.In recent years,transition-metal-catalyzed C-H bond functionalization has been proved to be a green and efficient method for the direct modification of indole pharmacophores.So far,the dehydrogenative cross-coupling of indoles with aromatics and alkenes has been widely studied.Notably,direct alkenylation of indoles exhibits to be more attractive approach to functinalized indoles due to the flexible transformation propertites of alkene functionality.However,the alkene coupling partners in these reactions are largely restricted to liner alkenes with obvious electronic bias,for example vinyl ketones(esters).Cyclic enones cannot be used in this coupling reactions owing to the substantial challenges.As an important kind of six-number cyclic enones,cyclohexenone is an excellent precursor of phenol.Undoubtedly,by taking advantage of C-H functionalization stratety to enable direct coupling of cyclohexenone with indole via would provide an economical and efficient approach to β-indolyl-sbustituted cyclohexenone compounds,expand the C-H bond functionalization chemistry of indoles,thus promote and accelerate the development and application of indole compounds in the field of synthetic and medicinal chemistry.In this thesis,we developed a mild palladium catalyzed indole C-H functinalization reaction wherein cyclohexenone can be successfully used as the coupling partner,the reaction proceeded under mild conditions to yieldβ-indolyl-sbustituted cyclohexenones.The produced coupling products are further converted into meta-indolyl phenols and benzo[a]carbazoles to demonstrated the utility of our developed methodology.The contents of this thesis are describled in 3 chapeters:In the first chapter,we outlined and summarized the regioselective C-H functionalization of indoles in detail.Among them,the dehydrogenation coupling reaction of indoles and linear alkenes is emphasized.In the second chapter,we communicated our development for synthesis of β-indolyl cyclohexenones through C-H functionalization strategy starting with commercial available indoles and cyclohexenones.After establishing optimal reaction conditions for dehydrogenative coupling,we examined the scope of the substrate,a series of β-indolyl cyclohexenone compounds with highly chemical-and regioselective were obtained that revealed the compatiblity this catalytic system.Finally,based on study of kinetic isotope experiments,we proposed a plausible mechanism for the coupling reaction.In the third chapter,we studied the application of the coupling products in the synthesis of meta-indolyl phenols and benzo[a]carbazole derivatives.Using β-indolyl-substituted cyclohexenones as the substrate,1)Dehydroaromatization was performed under the catalytic system of molecular iodine and DMSO,produced meta-indolyl phenolic compounds for the first time;2)At room temperature,the [4+2] cycloaddition reaction of coupling products with benzyne precurso to generate benzo[a]carbazole derivatives. |
