A Study On Preparation Of Trifluoromethylated Isocoumarins And Indole Polycyclic Heterocycles Via Cascade Reaction

Isocoumarin and indole are two kinds of important heterocycles,which have wide existence in various natural products and diverse important biological activities as well as medicinal usage.Therefore,it is of significant theoretical and practical application value to prepare diverse derivatives via structural modifications of their skeletons.Transition metal catalyzed C-H bond activation has became one of the hot topic of organic chemistry.Traditional methods require extra steps to install and remove the directing groups,which significantly diminish its atom and step economy.However,in recent years,the transient directing group strategy could overcome these limitations and improve its practical applications.This dissertation focused on the development of a series of cascade reactions to synthesize isocoumarin and indole derivatives in atom and step economical manner.Specifically,it includes the following aspects of research work.(1).A Ir-catalyzed oxidative coupling of benzoic acids with trifluoromethylated alkynes was successfully developed to provide diverse 3-and 4-trifluoromethylated isocoumarins.This new practical procedure used trifluoromethylated alkynes as versatile fluorine-containing building blocks and it was highlighted by easily avaliable starting materials,mild reaction conditions,broad substrate scope.(2).By using transient directing group assisted Pd-catalyzed oxidative cross coupling of indole-3-carbaldehyde with anisole to provide a series of indole polycyclic heterocycles.In this one-pot cascade reaction,the intermolecular and intramolecular sp2-sp2 carbon-carbon bond was formed respectively.Furthermore,these indole polycyclic heterocycles have special optical properties and have potential applications as organic probes.(3).In the absence of metal catalysts,indole-3-carbaldehyde could couple with two molecule of anisole to generate diaryl indole methane compounds in high efficiency.This catalytic system used trifluoroacetic anhydride as sole promoter and it was highlighted as mild conditions,broad substrate scope and high regioselectivity.