Study On Tandem Cyclization And Decarboxylation Coupling Reaction Catalyzed By Transition Metal Ruthenium

The reactions employing C-H bond activation possess the advantages including mild reaction conditions, broad substrates scope, which has been used in many research fields, such as pharmaceutical, pesticide, natural products and new materials. Up to date, transition metals including Au, Pd and Rh are the common used catalysts in C-H bond activation. However, the disadvantage of high price limits their applications. On the contrary, there is few reports employing cheap Ru as catalyst. Moreover, compared with other substrates, aromatic acids have several advantages, cheap, commercial available, safe e.g.. Therefore, the C-H bond activation using aromatic acids as starting material has attracted much interest.Based on the above cognition, this thesis mainly focuses on the following projects:In the first chapter, the preparations of N-substituted phthalic imides and N-aryl-substituted benzamide were reviewed.In the second chaper, employing cheap, commercial available, and safe carboxylic acids as starting materials, the [RuCl2(p-cymene)]2-catalyzed amidation of substituted benzoic acids with isocyanates via C-H functionalized/tandem cyclization to offord N-substituted phthalic imide is demonstrated. In the reaction, NaOAc, CuI and AgOTf were used as additive. The establishment of this method provides a simple and convenient route for synthesis of N-substituted phthalic imide. This approach has the advantages of simple and easy material, simple reaction operation, environmental friendliness, high atomic utilization.In the third chaper, we have succeeded in developing a ruthenium-catalyzed regiospecific ortho amidation of aromatic acid with concomitant decarboxylation. This protocol, which provides a convenient access to the synthesis of meta-substituted N-aryl benzamides derivatives, allows to use a less-expensive precious metal Ru(II) as catalyst and readily available acids and isocyanates as starting materials. In these reactions, the carboxyl functions effectively serve as a unique, removable directing group. More important is that this protocol can provide an efficient alternative to access meta-substituted N-aryl benzamides, which are much more difficult to prepare than ortho-substituted analogues.The last chapter, the full projects were summarized.