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    Home > Research group of Liu Guosheng, Shanghai Institute of organic chemistry: palladium catalyzed intermolecular aryl carbonylation of non active olefins -- introduction of large steric aromatic groups at room temperature

    Research group of Liu Guosheng, Shanghai Institute of organic chemistry: palladium catalyzed intermolecular aryl carbonylation of non active olefins -- introduction of large steric aromatic groups at room temperature

    • Last Update: 2018-11-07
    • Source: Internet
    • Author: User
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    The introduction of aryl groups into organic molecules with high selectivity has been one of the hot areas of organic chemistry research In the past few decades, transition metal catalyzed arylation reactions have attracted great attention of chemists, who have developed such reactions as Heck reaction, amine arylation and aryl halogenation, and these reactions have been widely used in organic synthesis However, the introduction of aryl steric hindrance in these reactions is not large; relatively speaking, the large steric hindrance of aryl is difficult to occur these reactions For example, the Heck reaction involving ortho disubstituted aryl often requires severe reaction conditions, and the yield is not ideal In particular, when asymmetric diaryl trivalent iodine (DAIS) is used as the arylation reagent, only the products with small steric hindrance are obtained How to introduce large steric hindrance into the reaction with high selectivity is very challenging (Fig 1) Recently, the research group of Liu Guosheng, researcher of Shanghai Institute of organic science, Chinese Academy of Sciences, has made a breakthrough in this field Using asymmetric diaryletrovalent iodine as an arylation reagent, palladium catalyzed aryl carbonylation of inactive olefins has been realized Under mild conditions, large sterically hindered aryl groups have been introduced into olefins with high selectivity Relevant research results were published in angew.chem Int ed (DOI: 10.1002 / anie 201810405) Figure 1 Transition metal catalyzed aromatization of olefins (source: angelw Chem Int ed.) introduction of research group of Liu Guosheng The research work of Liu Guosheng's research group is centered on the selective oxidation functionalization of olefins and Alkanes Catalyzed by transition metals, focusing on the two challenging scientific problems of "catalytic fluorination" and "asymmetric control of active radicals" in fluorine chemistry; based on the high activity of bonding reaction of high valence organic metal intermediates, the "metal coordination" is proposed New concepts and strategies, such as Homo free radical relay and metal coordinated electrophilic reaction, have successfully solved the above two problems, developed a series of new reactions of transition metal catalyzed oxidative fluorination and transition metal catalyzed asymmetric free radical conversion, and achieved some innovative research results, especially in metal catalyzed SP 3 Significant breakthroughs have been made in the asymmetric functionalization of hydrocarbon bonds Liu Guosheng, researcher of State Key Laboratory of metal organic chemistry, Shanghai Institute of organic chemistry, Chinese Academy of Sciences Graduated from Nanjing University of science and technology in 1995; obtained master's degree from Dalian Institute of Chemical Physics, Chinese Academy of Sciences in 1999; obtained doctor's degree from Shanghai Institute of organic chemistry, Chinese Academy of Sciences in 2002, under the guidance of academician Lu Xiyan; conducted postdoctoral research at the University of science and the University of Wisconsin Madison from 2003 to 2007; 2007 He was selected as the "Hundred Talents Program" of Chinese Academy of Sciences in and worked in Shanghai Institute of organic chemistry of Chinese Academy of Sciences He is mainly engaged in the research of transition metal catalytic oxidation, and explores the high-efficiency oxidation functionalization of olefins and alkanes Based on this, he explores many challenging scientific issues in the field of fluorine chemistry, such as metal catalytic fluorination and related reactions, asymmetric catalysis in free radical chemistry, and develops a series of new and high-efficiency oxidation functionalization reactions of olefins and alkanes As a corresponding author, he has published nearly 90 papers in the core academic journals of International Sci, including Science (1), acc.chem.res (2), j.am.chem.soc (17), angel.chem.int.ed (16), etc a single paper has been cited for more than 300 times, totaling more than 4500 times He has successively won "the first homogeneous catalysis Youth Award of the Chinese Chemical Society (2011)", "NSFC support for Distinguished Youth Science Fund (2012)", "Asian core program Leadership Award (Japan and Sigapore, 2012)", "Thieme Chemistry Journal Award (2012)", "outstanding 100 person program of the Chinese Academy of Sciences (2013)" ”"Excellent instructor award of the Chinese Academy of Sciences (2014)", "young and middle-aged talents in the field of scientific and technological innovation of the Ministry of science and Technology (2016)", "national ten thousand talents plan (2017)", "excellent teacher award of Zhu liyuehua of the Chinese Academy of Sciences (2016)", "outstanding academic leader of Shanghai (2017)", "leading talents of Shanghai (2017)" "BASF young people's Knowledge Innovation Award (2017)" and other honors Leading research achievements: palladium catalyzed intermolecular aryl carbonylation of non active alkenes -- introduction of large sterically hindered aryl diaryl trivalent iodine (DAIS) at room temperature )It is a kind of good source of aryl group, which has the advantages of non-toxic, air and water stability Compared with the commonly used aryl iodine, it has higher activity and is easier to form the aryl metal intermediate (AR m) by oxidation addition with transition metal However, when asymmetric dais is used, small sterically hindered aryl metal species (ARS m) are usually obtained after oxidation addition, thus small sterically hindered aryl groups are introduced into the molecules Only when the heteroatom nucleophiles react with asymmetric dais directly under the condition of non-metallic catalysis, the products with large steric hindrance can be obtained Therefore, it is very challenging to introduce large steric aromatic groups into olefins Based on the realization of oxo carbonylation, azido carbonylation and fluorocarbonylation of olefins by using phi (OAC) 2, arin 3 and ARIF 2 in the early stage of the research group, the author considers whether dais can be used to try the aryl carbonylation of olefins Preliminary experiments show that the product 3a of aryl carbonylation can be obtained, and it is a single product with large steric hindrance; meanwhile, a small amount of Heck reaction product 1a-2 with small steric hindrance, by-product 1a-1 of olefin isomerization and by-product 1a-3 of dicarbonylation can be obtained (Table 1) Based on these phenomena, the author thinks that the isomerization of olefins is caused by PDH species, and the addition of tempo can effectively inhibit the isomerization of olefins, while the addition of water can avoid the dicarbonylation of olefins Finally, the products with high regioselectivity and chemical selectivity can be obtained Table 1 Screening of reaction conditions (source: angelw Chem Int ed.), then the author expanded the reaction substrate (Fig 2), and different substituted end alkenes can obtain corresponding target products with high selectivity Halogens, alcohols, esters, ketones, borates and other functional groups are compatible In addition, heterocycles, such as carbazole, indole, thiophene, etc., will not affect the reaction In addition, in addition to the homotrimethylphenyl (MES), the large position hindered aryl group can also be other polysubstituted phenyl (4a-4i), as well as large position hindered heterocycles, such as indole, benzothiophene, etc (4m-4p) It is difficult to introduce these large sterically hindered aryls under mild conditions by other methods Fig 2 Substrate development (source: angelw Chem Int ed.) then, the author transformed the obtained products into multifunctional compounds with large steric hindrance groups, such as amidation, chlorination and azide of ester groups, etc Moreover, dais can also be produced in the field, and the standard reaction can be carried out directly, so as to realize the continuous "one pot" reaction from the large position blocking aryl group to the aryl carbonylation product, which makes the application of this method more convenient (Fig 3) Figure 3 Synthesis application (source: angelw Chem Int ed.) in order to understand the mechanism of this reaction, the author conducted in-depth research (Figure 4) The product 3a-d 3 (48%) of aryl carbonylation was obtained by the reaction of 1 A in deuterated methanol, and a small amount of product 6a-d3 and product 6b-d3 (18%) were detected In the absence of olefin substrate, 6a-d 3 and 6b-d3 were obtained in 42% and 15% yields, respectively However, in the absence of CO, only a small sterically hindered heck coupling product 7a was obtained, indicating that CO plays a very important role in the selective formation of AR SPD (II) and AR LPD (II) in the oxidation process of palladium In addition, AR s PD (II) and AR l PD (II) have different reactivity The former reacts with olefins, but is affected by CO pressure; the latter reacts directly with intercarbonylation The effects of electron effect and stereochemistry on the reaction were also investigated Figure 4 Mechanism experiment (source: angelw Chem Int ed.) finally, the author proposed the possible mechanism of the reaction (Figure 5) Firstly, palladium catalyst was oxidized by dais to form an aryl metal species dominated by AR LM under co condition, and then the olefins were CIS added to form int-iii instead of directly intercalated carbonyl (K 1 > k 4) The difference of activity between the two aryl metal species promoted the high selectivity of the reaction Figure 5 The possible mechanism (source: angelw Chem Int ed.) was recently published on angelw Chem Int ed (DOI: 10.1002 / anie 201810405) The first author of this paper is Li Xiang, a doctoral student from Shanghai Institute of organic science, Chinese Academy of Sciences The above research work was supported by the Ministry of science and technology, the National Natural Science Foundation of China, the strategic leading science and technology program of the Chinese Academy of Sciences (category B) and the Shanghai Municipal Science and Technology Commission 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.
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