Study On Photocatalytic Transformation Of Indoles

With the continuous resource shortage and environmental degradation,each country in the world devote to the development of new energy.Visible light,as a renewable energy,has been widely concerned by the society because of its green,efficient,low energy consumption and other characteristics.With the concept of "green chemistry"put forward,chemists are committed to apply visible light in the field of organic transformation,great progress has been made in the construction of structurally complex and diverse organic molecules.The indole framework widely occurs in natural products and drugs.Therefore,the modification of indole skeleton is of great significance in biomedicine.In this thesis,photocatalytic technology is applied to the reaction of indoles.The main purpose of this thesis is to study the ring-expansion,ring-opening and dearomatization of indoles to construct indole skeleton compounds with structural diversity under the condition of photocatalysis.This thesis mainly includes the following two parts:In the first part,an efficient and mild visible-light-enabled reaction involving the oxidative ring expansion of indoles with amidines in aqueous phase at room temperature was developed.Benzo[1,3,5]triazocin-6(5H)-ones and quinazolinones were facilely obtained as the terminal products by using 2-substituted indoles and substitutent-free indole as substrates,respectively.This protocol features transition metal free,room temperature,moderade to good yields and broad substrate scope,even reactions that cannot occur with traditional transition metal catalysis compared to transition metal catalysis.It provided a strong basis for studying the advantages of photocatalysis over traditional thermal reactionsIn the second part,an efficient synthesis of 2-azido-1-benzoylindolin-3-yl 2-benzamidobenzoate starting from(1H-indol-1-yl)(phenyl)methanone and trimethylsilyl azide(TMSN3)under an oxygen atmosphere is described.This novel protocol features a sequential reactions of dearomatization and ring-opening cascade reaction of indoles in one-pot manner,which overcame the shortcomings of tedious multi-step synthesis and poor orderliness of multi-component participation to construct azideindoline structure.The reaction is appreciated by its mild conditions,simple starting materials,high efficiency and controllability of multi-step reaction,which provides a new idea for the construction of indoline skeleton with diversity and complexity.In this thesis,a facile protocol for the synthesis of Benzo[1,3,5]triazocin-6(5H)-ones and 2-azido-1-benzoylindolin-3-yl 2-benzamidobenzoate compounds was established by means of visible light catalysis.The method has mild reaction conditions,good functional group compatibility,which provides novel green synthetic methods for the construction of structural diversity of indole skeleton compounds.It's also an effective supplement and breakthrough to the the traditional pathway of indole conversion.