Green chemistry, research group of Wei Wei, associate professor of Qufu Normal University: visible light induced oxidative coupling reaction of aryl azosulfone with mercaptan to construct asymmetric sulfoxide

Lead sulfoxide is a valuable sulfur-containing organic compound It not only exists in a large number of natural products and pharmacological active compounds, but also is often used to construct various important drug molecules The traditional synthesis method mainly depends on the oxidation of thioether This kind of reaction generally uses the stoichiometric high valent iodine or peroxide as the oxidant, and completes the oxidation under the catalysis of various metals such as copper, titanium, cobalt, silver and zinc Recently, the research group of Wei Wei, associate professor of Qufu Normal University, has realized the oxidative coupling reaction of aryl azosulfone with mercaptan under the condition of no photocatalyst and additional oxidant by using the visible light induction strategy (Figure 1) The related research results were published in green Chem (DOI: 10.1039 / c9gc00222g) under the title of "catalyst free light initiated oxidizing combining of arydiazo sulfines with thisolsleeping to unsymmetrical sulfides in air" Figure 1 Visible light induced oxidative coupling reaction of aryl azosulfone and mercaptan to construct asymmetric sulfoxide At present, there are 5 postgraduate students in the research group Based on the concept of "green synthetic chemistry", the research group has constructed some simple, green and efficient new methods of compound synthesis aiming at the synthesis of bioactive drug intermediates The research direction of the research group mainly includes photocatalytic reaction, free radical reaction, oxidation reaction with oxygen participation and asymmetric catalytic reaction Wei Wei, Ph.D in pharmaceutical chemistry, associate professor of Qufu Normal University, Youqing, Shandong Province, engaged in postdoctoral research on green synthesis in McGill University, Canada from 2016 to 2017 (co tutor Professor Li Chaojun); obtained Ph.D in pharmaceutical chemistry from Chengdu Institute of biology, Chinese Academy of Sciences in 2012; obtained master's degree in organic chemistry from Sichuan University in 2008 Since his independent work, he has been committed to the research of green synthetic chemistry and pharmaceutical chemistry He has published more than 80 SCI papers in the international journals such as angelw Chem Int ed., chemical science, green chemistry, organizational letters, etc., which have been cited for more than 2000 times and H factor 26 Four papers were highly cited by ESI, with a maximum of 173 citations for a single paper, and 5 provincial and department level science and technology awards Leading scientific research achievements: visible light induced oxidative coupling reaction of aryl azosulfone and mercaptan to build asymmetric sulfoxide First, the author optimized the reaction conditions with p-methoxyphenyl azomethylsulfone 1a and phenylthiophenol 2A as raw materials (Figure 2) The author found that when acetonitrile / water (9 / 1) was used as the mixed solvent, all kinds of photocatalysts were screened under the blue LED light, and the results were very similar Therefore, the author further investigated the effect of no photocatalyst on the reaction, and found that the reaction can take place smoothly, and the target product (entry 7) was obtained in 62% yield After further screening of the solvent, the author found that acetonitrile / water (1 / 1) was more effective and the yield of the product reached 79% (entry 18) Figure 2 Screening of reaction conditions (source: Green Chemistry) Next, the author studied the substrate range of the reaction (Figure 3) The position and electric property of the substituent group of aryl thiophenol have no obvious influence on the reaction Heterocyclic Thiophenol and aliphatic thiol can also be well compatible with the reaction and get a better yield The position and electrical properties of substituents on aryl azosulfone have no obvious influence on the reaction, and the products can be obtained in medium to good yields Figure 3 Substrate expansion (source: Green Chemistry) based on a series of control experiments, the author proposes a possible reaction mechanism (Figure 4): first, aryl azosulfone generates aryl radicals under visible light irradiation; thiophenol generates thiol radicals under air oxidation, and its self polymerization yields disulfide Then, the aryl radicals are coupled with disulfide to form thioether 5 Finally, thioether 5 is oxidized by singlet oxygen to form sulfoxide Figure 4 Possible reaction mechanism (source: Green Chemistry) Summary: the author developed an environmentally friendly method for the oxidative coupling reaction of aryl azosulfone with mercaptan to synthesize sulfoxide A series of unsymmetrical sulfoxides were constructed by using clean light energy, acetonitrile and water as solvent, air as oxidant and without photocatalyst The reaction substrate has a wide range and good functional group tolerance, which provides a simple and green synthesis method for sulfoxide Relevant research results were published in green chem (DOI: 10.1039/c9gc00222g) Liu Qishun, a first year student of Qushi University, and Wang Leilei, a third year student of Qushi University, are the co first authors of the article The corresponding author is Wei Wei, an associate professor of Qushi University The related work was supported by the National Natural Science Foundation of China and the natural science foundation of Shandong Province Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.