echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Professor Wang Baiquan, Nankai University Research Group: Cp * Rh (III) catalysed C-H / C-C bond breaking and cyclization to synthesize cyclopentyl [b] carbazole derivatives

    Professor Wang Baiquan, Nankai University Research Group: Cp * Rh (III) catalysed C-H / C-C bond breaking and cyclization to synthesize cyclopentyl [b] carbazole derivatives

    • Last Update: 2020-01-09
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com
    Lead carbazole skeleton is widely found in natural products and drug molecules Many molecules containing carbazole units have antitumor, antimalarial and antifungal effects, and also have a certain relieving effect on hypertension Therefore, it is of great significance to develop efficient construction methods of carbazole skeleton In the past decade, transition metal catalyzed C-H bond functionalization has been developed rapidly Due to its high atomic economy and step economy, C-H bond functionalization has been widely used in the construction of various carbon carbon and carbon heterobonds Although this kind of reaction is simple and efficient, it often depends on the coordination guidance of the guiding group to realize highly selective C-H bond functionalization However, the groups (such as pyridine, pyrimidine, imine, carbonyl, etc.) which are often used as guiding groups need more stringent conditions to be removed from the target product structure The non trace guiding group (which can be removed in situ after coordination guiding) can effectively solve this problem and greatly improve the efficiency and applicability of the reaction In recent years, the functionalization of C-H bond assisted by carboxyl, aldehyde, nitroso, NOx and pyridylamide has been reported Amide is also a structural unit widely existing in natural organic skeleton Recently, Wang Baiquan group of Nankai University has realized the functionalization of C-H bond assisted by amide as traceless guiding group Under the catalysis of Cp * Rh (III), the chain breaking and cyclization of C-H / C-C bond of amide as traceless guiding group have been realized to efficiently construct cyclopentyl [b] carbazole derivatives Relevant research results were published in org Lett (DOI: 10.1021/acs.orglett.9b03969) Brief introduction of Professor Wang Baiquan's research group Professor Wang Baiquan's research group has 1 Professor, 1 associate professor, 5 doctoral students, 7 master's students, relying on the National Key Laboratory of organic elements of Nankai University The current research work of our group includes: 1 Organometallic chemistry activated by C-H bond Based on the understanding of the reaction mechanism, a new and efficient transition metal catalyzed C-H bond activation and transformation reaction was designed and developed 2 Design, synthesis and catalytic polymerization of transition metal polymerization catalyst This paper focuses on the design and synthesis of transition metal compounds based on anion N-heterocyclic carbene ligands, studies their catalytic performance in coordination polymerization, ring opening metathesis polymerization and other polymerization reactions, and develops high-efficiency polymerization catalysts with independent intellectual property rights 3 Transition metal catalyzed activation and transformation of carbon dioxide Carbon dioxide is used as C1 resource to develop transition metal catalyzed C-C coupling reaction between organic substrate and carbon dioxide to synthesize high value-added organic compounds Wang Baiquan, professor and doctoral supervisor of School of chemistry, Nankai University, is currently vice president of School of chemistry, Nankai University In 1990, 1993 and 1996, he received bachelor's degree, master's degree and doctor's degree from Nankai University respectively, and his tutor was Professor Zhou Xiuzhong He stayed in the Department of chemistry of Nankai University in July 1996 and has been a lecturer, professor and doctoral supervisor ever since From March to December 1997, he worked as a visiting scholar in the Department of chemistry of the Chinese University of Hong Kong, under the guidance of Professor Xie Zuowei From September 1999 to August 2000, he went to the University of Texas at Austin to do postdoctoral research, under the guidance of Professor J J lagowski Mainly engaged in Organometallic Chemistry and homogeneous catalysis More than 170 SCI papers have been published and 11 Chinese invention patents have been authorized In 1998, he won the second prize of the Ministry of education for scientific and technological progress, the first prize of Tianjin teaching achievement in 2018, and the outstanding teacher award of Baosteel in 2019 In 2004, it was selected into the "new century talent support plan" of the Ministry of education Member of the 29th and 30th Chemical Education Committee of the Chinese chemical society, member of the University Chemistry Curriculum Teaching Steering Committee of the Ministry of education Leading scientific research achievements: Wang Baiquan, Professor of Nankai University of transition metal catalyzed multiple C-H bond activation, has done a series of innovative works in the field of transition metal catalyzed multiple C-H bond activation (J am Chem SOC 2012, 134, 16163; angel Chem Int ed 2014, 53, 4191-4195; org Lett 2016, 18, 2483; org Lett 2016 , 18 , 2816; Org Lett 2016 , 18 , 5066; Chem Commun 2017 , 53 , 6343; Chem Commun 2018 , 54 , 9147 ) 。 A series of fused ring compounds are constructed by the activation of multiple C-H bonds catalyzed by transition metals These molecules have potential applications in medicine, materials and so on It has been previously reported that n-assisted C-C bond breaking can be realized under the catalysis of Cp * Rh (III), while 1,6-diynes can play the role of guiding group by using the weak coordination of alkynes in the reaction process Professor Wang Baiquan's research group uses amide as the guiding group to realize the coupling of guiding and one alkyne unit, and then realize the fracture of C-C bond with the assistance of another alkyne unit, and then realize the cyclization reaction, so as to construct the carbazole framework efficiently This method has the advantages of simple reaction conditions, good functional group compatibility, wide range of substrate application, high yield and good regional selectivity Fig 1 The design of a new traceless guide group (source: org Lett.) the author explored the reaction with indole (1o) and 1,6-diacetylene (2a) substituted by 3-acetyl (Fig 2) Using [Cp * RhCl 2] 2 as catalyst, agsbf 6 as additive, Cu (OAC) 2 · H 2O as oxidant and DCE as solvent, the target product was obtained in 12 hours at 100 ˚ C with 43% NMR yield 3-carboxyl, formyl, ester, amide substituted indoles can give corresponding products, among which 1a is the best Furthermore, the author further optimized the conditions with 1a and 2A as standard substrates, and determined the optimum conditions: 5 mol% of [Cp * rhcl2] 2 as catalyst, 20 mol% of agsbf 6 as additive, 2.0 equivalent of agoac as oxidant, 1.0 ml of DCE as solvent, 0.1 mmol of 1a and 0.12 mmol of 2a, reacting in 100 OC argon for 12 hours Fig 2 Selection of guiding basis (source: org Lett.) under the optimal conditions, the author investigated the application scope of substrate The first is indole substrate (Fig 3) When the reaction feed is enlarged to 1 mmol, a higher yield can also be obtained When the substituents at 4,5,6,7 of indole were introduced, the yield of the substituents was 56 - 95% In addition to n-methylindole, n-benzylindole can also give 88% yield Indoles without substituents on N can also react well Thiophene derivatives 1 m and 1 N can also react to give the corresponding heterocyclic sulfur compounds Next, we extend the diyne substrate (Fig 4) The heterocycles such as thiophene group or alkyl group can get a good yield (52-88%) by introducing phenyl with electron absorption or electron supply at the end of diyne The bridging group of diyne was extended In addition to diesters, ethyl acetoacetate, diketones, such as acetylacetone, damidone and 1,3 indenedione also have good adaptability to the reaction Among them, damidone, 1,3 indenedione can also obtain spiro compounds Good yield can also be obtained by using O or n-ts as bridge substituent For asymmetric diyne, because of the influence of electronic effect, two isomer products will be obtained, and the total yield is also very high Fig 3 Applicability of indoleamide (source: org Lett.) Fig 4 Applicability of 1,6-diacetylene (source: org Lett.) in order to better understand the mechanism of the reaction, the author launched a series of experimental exploration First of all, the author carried out a control experiment, and found that 1A could not remove the guiding group under the standard conditions, and 3-amide substituted indole substrate and monoacetylene could not react, indicating that the intrinsic molecular characteristics of diyne contributed to the reaction Secondly, the results of H / D exchange experiments show that the fracture of C-H bond in the system is irreversible The results of parallel kinetic isotope effect (KIE) experiments show that the fracture of the C-H bond in the reaction may not be included in the rate determination step Competitive experiments show that the reaction is more likely to take place in electron rich indoles Figure 5 Mechanism exploration (source: org Lett.) based on the above research and combined with the literature reports, the author proposed the possible mechanism of the reaction: [Cp * RhCl 2] 2 forms the active rhodium intermediate Cp * RHX 2 under the action of Ag salt; then, with the assistance of amide group, through the mechanism of collaborative metallization (CMD), the ortho-c-h bond activation occurs, forming the five membered ring rhodium intermediate I Second, one alkyne unit is transferred and inserted into the C-Rh bond to form the seven membered ring intermediate III, and then five membered ring rhodium intermediate IV is formed by indole dearylation assisted by another alkyne unit; then, the guide group is removed by the reverse reaction of Funke reaction assisted by acetate radical, and the other alkyne unit pair The rh-c bond is transferred and inserted to form a seven membered rhodium intermediate v finally, the target product is obtained by reduction and elimination, and the monovalent rhodium produced is oxidized by silver acetate to regenerate the active rhodium intermediate, which enters the next catalytic cycle Figure 6 Possible mechanism (source: org Lett.) this achievement was published in org Lett (DOI: 10.1021 / ACS Orglett 9b03969) The first author of this paper is Wang Yanwei, a doctoral student of Nankai University, and the corresponding author is Professor Wang Baiquan of Nankai University The above research work is supported by the National Natural Science Foundation of China (No 21672108) 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.
    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.