| Nitrogen-containing heterocycles compounds is a kind of very important heterocyclic compounds,which have been widely used in chemical industry such as pesticide,medicine and material.As a core skeleton in many natural products and synthetic material,carbazole is widely used in pharmaceutical industry and photoelectric materials.Accordingly,the development of a simple,green and efficient method to construct carbazoles is a fundamentally important but challenging project.Visible light as a kind of green natural resources has attracted chemists' attention,and been applied in organic synthesis.In view of the needs of developing green and sustainable chemistry,visible light promoted or visible light-catalysed chemical synthesis has attracted the research interests of chemists from the turn of the century,and has now become one of the most popular research areas.In this project,we designed and synthesized a kind of indole-derived bromides,through which a range of multi-substituted carbazoles were synthesized through a visible light-photocatalysed formal(4+2)cycloaddition with alkynes.After a series of conditions screening(e.g.,catalyst,solvent,base),we established the optimal reaction conditions:fac-Ir(ppy)3 as the photocatalyst,sodium carbonate as the base,dichloromethane as the solvent,irradiation under 3 W blue LEDs.Under the optimal reaction conditions,we investigated substrates scope of indole-derived bromides and the alkynes.Through the experiment we found that the electronic effect and steric effect have no obviously influence to the reaction,and various substituted indole-derived bromides and alkynes can be applied to the reaction,and various muti-substituted carbazole products can be obtained.All the synthesized substrates and products were characterized by NMR,IR,HRMS,M.P.,and the structure as well as the selectivity of product were confirmed by X-ray analysis.According the related literature,a proposed mechanism was proposed. |
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