Visible Light Catalytic Oxidation And Tandem Ring Formation Reaction

Solar energy is a unique resource in nature. During recent years, visible light photoredox catalysis has the advantages of high efficiency, mild conditions and simple operation. In addition, it is easy to control and realize tandem reaction.Therefore, it has attracted much attention form scientists. And it has been widely used in organic synthesis. In this dissertation, we have described the latest research progress of visible light photoredox catalysis in this field. Based on this strategy, we carried out a series of studies.The main contents of this thesis include the following two parts:1. Synthesis of 1,2-diketones via a metal-free,visible-light-induced aerobic photooxidation of alkynes.We have synthesized 1,2-diketones through the oxidation of alkynes using cheap eosin Y as a photocatalyst. The reaction took place upon the irradiation of visible light at room temperature and it did not need transition metal as a catalyst. The substrates were suitable for the transformation and they had a good chemical selectivity.Through the mechanism of research,we found that oxygen played a very important role in the reaction. The oxygen atoms in the carbonyl group are derived from oxygen molecules.2. Visible light-promoted synthesis of sulfonated isoquinoline-1,3-(2H,4H)-diones via a tandem radical cyclization.We have synthesized sulfonated isoquinoline-1,3-(2H,4H)-diones by using the cheap and easy sulfonyl chorides as the source of sulfone,fac-Ir(ppy)3 as the photocatalyst, 5 W LED as the light source. The reaction occurred through a tandem radical cyclization. The transformation proceeded smoothly in mild conditions and it exhibits a good tolerance for a broad range of general functional groups. It was worth mentioning that when the product isoquinoline-1,3-(2H,4H)-dione was under the reduction of NaBH4, the C3-carbonyl group could be selectively reduced to hydroxyl group.