Dr. Ma Yanna, Henan Normal University: visible light mediated remote SP3 C-H activation: efficient construction of fluoroketones

Dr Ma Yanna from Henan Normal University has long been committed to the green and efficient synthesis of organic compounds Recently, the research group has realized the green and efficient synthesis of fluoroalkanone through the bifunctional group initiated by olefin fluoroalkylation with alkene as the substrate The results were published in org Lett (DOI: 10.1021 / ACS Orglett 9b03594) This work was completed jointly with Li Lixin group of Xinyang Normal University Dr Ma Yanna is an associate professor of Henan Normal University Graduated from Lanzhou University in 2017, under the guidance of Professor Yang Shangdong, engaged in the synthesis of organophosphorus compounds In 2017, he joined the Chen xuenian research team of Henan Normal University to carry out scientific research, mainly engaged in the research of green synthetic chemistry and organic boron chemistry At present, as the first author or corresponding author, he has published more than ten related research results in the international mainstream academic journals of chemistry such as acc chem Res., green Chem., org Lett., J org Chem., chem EUR J Cutting edge research achievements: visible light mediated remote sp 3c-h activation: efficient construction of fluoroketone containing organic molecules plays an important role in natural products, drug molecules and material chemistry In recent years, many chemists have been interested in it, and many strategies have been developed to construct these compounds Among them, the functionalization of olefins and the introduction of fluorine-containing groups have become a very popular way (Figure 1) Based on the previous work, the functionalization of styrene was developed to sp 3 C-H oxidation by 1,5-hat strategy, and the synthesis of fluoroketones was realized The key point of this reaction is the functionalization of olefins initiated by free radicals, the C-H activation of benzyl site by 1,5-hat strategy, and the highly selective activation and functionalization of remote sites The oxygen atom in DMSO is successfully introduced into the target molecule Under the guidance of this method, a series of 1,6-difluoroalkyl ketones can be obtained rapidly at room temperature Figure 1 The method of constructing fluorine-containing organic molecules (source: org Lett.) under optimized conditions, the author studied the universality of the reaction Firstly, the olefin substrate was screened with ethyl bromodifluoroacetate as the fluorine source (Fig 2) Both o-allylalkylbenzenes and aryl linear alkenes can be used in this reaction to obtain the target product with excellent chemical selectivity At the same time, the substituents on the aromatic ring were investigated and found to have good compatibility with halogens, alkyl groups, alkoxy groups and heterocycles Figure 2 Application scope of substrate (source: org Lett.) next, the author investigated different fluoroalkyl sources (Figure 3) In addition to ethyl bromodifluoroacetate as a source of fluorine, bromodifluoroacetamide and bromopolyfluoroalkyl can also be used as a source of fluorine to obtain a variety of fluoroalkanones in a medium to high yield Figure 3 Substrate application (source: org Lett.) in addition, the mechanism of the reaction was studied When the free radical trapping agent was added to the reaction system, the adduct of ethyl difluoroacetate free radical with tempo and 1,1-stilbene was captured, indicating the formation of ethyl difluoroacetate free radical in the reaction process At the same time, using DMSO labeled with oxygen-18 as solvent, we obtained the product of haloalkanone labeled with oxygen-18 This experiment shows that the oxygen on ketone comes from DMSO Fig 4 Mechanism study (source: org Lett.) based on mechanism experiments and related literature reports, the author proposed the following reaction mechanism (Fig 5): ethyl bromodifluoroacetate produces ethyl difluoroacetate free radical under the action of photocatalyst and light, ethyl difluoroacetate free radical adds the double bond to obtain the intermediate of alkyl free radical 1a-i, 1a-i The intermediate 1a-i I I was obtained by 1,5-hat, and the intermediate 1a-i I I was oxidized to obtain benzyl positive ion 1a-i II The target product was obtained by Kornblum reaction between 1a-i II and DMSO Figure 5 Possible reaction mechanism (source: org Lett.) the research results are published in org Lett (DOI: 10.1021/acs.orglett 9b03594) This scientific research achievement has been greatly supported by the National Natural Science Foundation of China and the scientific research start-up project of Henan Normal University 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 website, chembeangoapp, chembeango official micro blog, CBG information wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the representative research groups in China, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit