| As a green and clean energy,visible light has been widely used in solar cell and water photodissociation.Different from non-renewable energy sources such as coal and oil,solar energy is the most abundant and accessible energy source in nature.Plants have been transfering carbon dioxide into carbohydrates through photosynthesis for billions of years.From the early 20 th century,visible light energy has been used in chemical synthesis.Now,visible light photoredox catalysis,as a new catalytic model,has become a hot topic in the field of organic photochemistry.Combining photocatalysis with other catalytic modes have been developed a series of new reaction systems.The main goal is to overcome the limitation of the single catalytic model in terms of the type of reaction and the applicable range of substrates.Therefore,we hope to design a new photochemical co-catalysis model and realize a concise,green and efficient synthetsis of valuable compound.This paper is mainly divided into the following four parts:Chapter 1: Co-catalytic strategies in photochemical synthesis.First,we reviewed the development of photochemistry and introduced the basic principle of visible light photordox catalysis Then,we classified the common photocatalysts as metallic and organic photocatalyst.Last,the characteristics of synergistic photocatalysis were summarized.Chapter 2: Dehydrogenative silylation of alkenes for the synthesis of substituted allylsilanes by photoredox,hydrogen-atom transfer,and cobalt catalysis.Silicon-containing compounds have played very important roles in organic chemistry owing to their unique chemical,physical,and bioactive properities.Allylsilanes are regarded as one of the vital building blocks in the synthesis of small molecules and polymers because of their high stability and low toxicity.Therefore,the development of a mild and efficient method for the introduction of silicon groups into organic molecules has attracted lots of interest in recent years.Herein,a synergistic catalytic method combining photoredox catalysis,hydrogen-atom transfer,and protonreduction catalysis for the dehydrogenative silylation of alkenes was developed.With this approach,a highly concise route to substituted allylsilanes has been achieved under very mild reaction conditions without using oxidants.This transformation features good to excellent yields,operational simplicity,and high atom economy.Chapter 3: Alkene functionalization for the stereospecific synthesis of substituted aziridines by visible-light photoredox catalysis.Three-membered ring heterocycles,especially aziridines are ubiquitous structural motifs in natural products,pharmaceuticals and biologically active molecules.Meanwhile,aziridines have been well known as a significant class of synthons for synthetic elaborations and functional group transformations because of the intrinsic ring strain.Herein,a novel strategy involving visible-light-induced functionalization of alkenes for the synthesis of substituted aziridines was developed.The readily prepared N-protected 1-aminopyridinium salts were used for the generation of N-centered radicals.This approach allowed the synthesis of aziridines bearing various functional groups with excellent diastereoselectivity under mild conditions.Moreover,this protocol was successfully applied to prepare structurally diverse nitrogen-containing frameworks.Chapter 4: Visible-Light Induced Generation Dual Reaction Sites NitrogenCentered Radicals: A Concise Synthesis Strategy to Construct Bicyclo[3.2.1]octane and Azepane CoresA photocatalytic [2+2+1] and [6+1] cyclization of o-alkenyl benzaldehyde using pyridinium salts as the amination reagent is described.A variety of novel bridged-ring and azepane skeletons are prepared in modest to excellent yields with expeditious onestep route.This transformation features mild reaction conditions and exceptional functional group tolerance.Additionally,this skillful strategy may be appealing for the synthesis of biologically active molecules. |
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