| Indole as a kind of important natural alkaloid,has ubiquitous existence in nature.The componds bearing indoles skeleton possess various biological activities and medicinal value.Therefore,it is of great practical application value and important theoretical research significance to modify the indole scafolds for preparation of various indole derivatives with structural diversity.For the last two decades,the modification of molecular structure through direct activation of inert C-H bond has become a new frontier reasearch area for organic chemistry.However,the traditional transition metal catalyzed C-H activation require two additional steps for installation and removal of the covalent bond connecting directing groups,which greatly reduced the step and atom economy.Very recently,transient directing group assisted transition metal catalyzed the C-H activation can overcome the above shortcomings,and significantly enhance the reaction efficiency and practical usage.In this dissertation,a series of indoles derivatives have been successfully synthesized in high efficiency with high atom economy under mild conditions using transient directing group strategy.It mainly includes the following two aspects:(1)A new strategy for transient directing group enabled palladium catalyzed halogenation on the 4-position of N-protected-indole-3-formaldehyde was developed using N-chlorosuccinimide,N-bromosuccinimide and N-iodobutylimide,respectively.The reaction has the advantages of good substrate tolerance,mild conditions and easy access to starting materials.(2)A series of indole fused polycyclic compounds bearing trifluoromethyl and nitro groups were prepared via rhodium catalyzed oxidative annulation of2-nitrovinyl-indoles with trifluoromethylphenylacetylenes.It is noteworthy that the free amine of indole acted as traceless directing group and embodied in the products.Excellent regioselectivity was achieved by electronic property adjustment. |
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