Visible Light Driven Generation Of ?-aminoalkyl Radicals And N-radicals Utilizing Rose Bengal

The greatest crisis of mankind in the 21 st century is the energy crisis.As a green,rich and easily available sustainable energy source,visible light has received more and more attention in the context of the increasing shortage of resources and energy.The sun radiates a large amount of energy to the earth every year.Thus the development and utilization of light energy is one of the ways to solve energy problems.In the past decade,visible light catalysis has caused widespread concern among chemical workers.Chemists used light as a powerful tool to achieve many difficult reactions and overcome the shortcomings of the traditional methods.It is currently known that photocatalysis has been successfully applied in the construction of C-C,C-N,C-S,C-O and other bonds.However most photocatalysts used in photocatalytic reactions are metal complexes.These metal complexes are expensive,difficult to handle,and potentially biologically toxic.In contrast,organic dyes as photocatalysts have the advantages of being cheap,readily available,green and easy to prepare.In the second chapter of this thesis,the reaction for the synthesis of tetrahydroquinoline derivatives through the cyclization of N,N-dimethylanilines and2-benzylallylmalonitriles was studied using Rose Bengal as a photosensitizer under visible light irradiation.Tetrahydroquinoline derivatives are a very important class of compounds and tetrahydroquinoline fragments are also a common part of many natural products and bioactive molecules.This reaction generates ?-amino radicals by oxidizing N,N-dimethylanilines,and then the resulting ?-amino radicals are cyclized with2-benzylallylmalonitriles to produce the products.Through this method we obtained 20 tetrahydroquinoline derivatives with yields of up to 74%.This work shows a synergistic advantage of combining trifluoroacetic acid(TFA)with Rose Bengal and may provide a promising solution for the synthesis of tetrahydroquinoline derivatives.In the third chapter of this thesis,the reaction of olefin amination in the presence of visible light was studied.The direct formation of C(sp2)-N bonds by the cross-couplingof olefins and N-H has always been a goal of chemists.The current mainstream method is the cross-coupling of olefins and halides catalyzed by transition metals(Cu,Pt,Hg,etc.).However,these methods have some insurmountable disadvantages such as poor atomic economy,metal residues,hard reaction conditions,toxic oxidants or prefunctionalization.N-vinylazoles is a very important class of compounds,and the N-vinylazoles moiety is an important block that is usually found in natural products,drugs,and conjugated polymers.Therefore,finding effective methods for the formation of C(sp2)-N bonds in N-vinyl oxazoles has been an important issue in the pharmaceutical industry.Herein we developed a simple and effective direct alkene C-H amination method to synthesize N-vinyl oxazole.This strategy is very green because it uses visible light as energy,air as an oxidant,and organic dye Rose Bengal as a photosensitizer to directly build C(sp2)-N bonds at room temperature in atom-and step-economic manner.This new method can rapidly synthesize N-vinylazole skeleton,and 28 products were obtained with yields of up to 86%.These advantages make this method very competitive in the synthesis of N-vinylazoles.