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1.
Prof. Dr. David Y.‐K. Chen Prof. Dr. So Won Youn 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(31):9452-9474
The recent advent of transition‐metal mediated C? H activation is revolutionizing the synthetic field and gradually infusing a “C? H activation mind‐set” in both students and practitioners of organic synthesis. As a powerful testament of this emerging synthetic tool, applications of C? H activation in the context of total synthesis of complex natural products are beginning to blossom. Herein, recently completed total syntheses showcasing creative and ingenious incorporation of C? H activation as a strategic manoeuver are compared with their “non‐C? H activation” counterparts, illuminating a new paradigm in strategic synthetic design. 相似文献
2.
Manganese(I)‐Catalyzed C−H Activation: The Key Role of a 7‐Membered Manganacycle in H‐Transfer and Reductive Elimination 下载免费PDF全文
Dr. Nasiru P. Yahaya Kate M. Appleby Magdalene Teh Conrad Wagner Erik Troschke Joshua T. W. Bray Prof. Simon B. Duckett L. Anders Hammarback Dr. Jonathan S. Ward Jessica Milani Dr. Natalie E. Pridmore Dr. Adrian C. Whitwood Dr. Jason M. Lynam Prof. Ian J. S. Fairlamb 《Angewandte Chemie (International ed. in English)》2016,55(40):12455-12459
Manganese‐catalyzed C?H bond activation chemistry is emerging as a powerful and complementary method for molecular functionalization. A highly reactive seven‐membered MnI intermediate is detected and characterized that is effective for H‐transfer or reductive elimination to deliver alkenylated or pyridinium products, respectively. The two pathways are determined at MnI by judicious choice of an electron‐deficient 2‐pyrone substrate containing a 2‐pyridyl directing group, which undergoes regioselective C?H bond activation, serving as a valuable system for probing the mechanistic features of Mn C?H bond activation chemistry. 相似文献
3.
Si‐Hua Hou Adriana Y. Prichina Mengxi Zhang Guangbin Dong 《Angewandte Chemie (International ed. in English)》2020,59(20):7848-7856
To show the synthetic utility of the catalytic C?C activation of less strained substrates, described here are the collective and concise syntheses of the natural products (?)‐microthecaline A, (?)‐leubehanol, (+)‐pseudopteroxazole, (+)‐seco‐pseudopteroxazole, pseudopterosin A–F and G—J aglycones, and (+)‐heritonin. The key step in these syntheses involve a Rh‐catalyzed C?C/C?H activation cascade of 3‐arylcyclopentanones, which provides a rapid and enantioselective route to access the polysubstituted tetrahydronaphthalene cores presented in these natural products. Other important features include 1) the direct C?H amination of the tetralone substrate in the synthesis of (?)‐microthecaline A, 2) the use of phosphoric acid to enhance efficiency and regioselectivity for problematic cyclopentanone substrates in the C?C activation reactions, and 3) the direct conversion of serrulatane into amphilectane diterpenes by an allylic cyclodehydrogenation coupling. 相似文献
4.
Chiral Counteranion Strategy for Asymmetric Oxidative C(sp3)H/C(sp3)H Coupling: Enantioselective α‐Allylation of Aldehydes with Terminal Alkenes 下载免费PDF全文
Pu‐Sheng Wang Hua‐Chen Lin Yu‐Jia Zhai Zhi‐Yong Han Prof. Dr. Liu‐Zhu Gong 《Angewandte Chemie (International ed. in English)》2014,53(45):12218-12221
The first enantioselective α‐allylation of aldehydes with terminal alkenes has been realized by combining asymmetric counteranion catalysis and palladium‐catalyzed allylic C? H activation. This method can tolerate a wide scope of α‐branched aromatic aldehydes and terminal alkenes, thus affording allylation products in high yields and with good to excellent levels of enantioselectivity. Importantly, the findings suggest a new strategy for the future creation of enantioselective C? H/C? H coupling reactions. 相似文献
5.
Wolfgang Kirmse 《Angewandte Chemie (International ed. in English)》1997,36(11):1164-1170
Alkenylidenes R2C?C: (= alkylidene carbenes) undergo regio- and stereoselective intramolecular C? H insertion reactions that are excellently suited for the synthesis of cyclopentenes. The 1, 2-shifts occurring with R?H and R?Ar are useful for the preparation of alkynes. Alkenylidenes are efficiently generated from carbonyl compounds by diazomethylation, from vinyl halides by α-elimination, from alkynyliodonium salts by addition of nucleophiles, and from alkynes by retro-1, 2-shifts. Specific applications of the various methods, particularly in the synthesis of natural products, are discussed. 相似文献
6.
Ashish A. Mishra Dnyaneshwar Subhedar Bhalchandra M. Bhanage 《Chemical record (New York, N.Y.)》2019,19(9):1829-1857
This review represents nickel, cobalt and palladium catalyzed C?H activation of sp3 carbon, with special emphasis on methyl C?H activation. The importance of directing group assistance and effect of ligand on β‐ or γ‐ C(sp3)?H activation is summarized in this review. The mechanistic study for Ni, Co and Pd catalyzed sp3 C?H bond functionalization also discussed in detail. 相似文献
7.
Copper‐Catalyzed Aerobic Oxidative Inert CC and CN Bond Cleavage: A New Strategy for the Synthesis of Tertiary Amides 下载免费PDF全文
Xiuling Chen Dr. Tieqiao Chen Qiang Li Dr. Yongbo Zhou Prof. Li‐Biao Han Prof. Shuang‐Feng Yin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(38):12234-12238
A copper‐catalyzed aerobic oxidative amidation reaction of inert C?C bonds with tertiary amines has been developed for the synthesis of tertiary amides, which are significant units in many natural products, pharmaceuticals, and fine chemicals. This method combines C?C bond activation, C?N bond cleavage, and C?H bond oxygenation in a one‐pot protocol, using molecular oxygen as the sole oxidant without any additional ligands. 相似文献
8.
Ligand‐Enabled Catalytic CH Arylation of Aliphatic Amines by a Four‐Membered‐Ring Cyclopalladation Pathway 下载免费PDF全文
Dr. Chuan He Prof. Matthew J. Gaunt 《Angewandte Chemie (International ed. in English)》2015,54(52):15840-15844
A palladium‐catalyzed C? H arylation of aliphatic amines with arylboronic esters is described, proceeding through a four‐membered‐ring cyclopalladation pathway. Crucial to the successful outcome of this reaction is the action of an amino‐acid‐derived ligand. A range of hindered secondary amines and arylboronic esters are compatible with this process and the products of the arylation can be advanced to complex polycyclic molecules by sequential C? H activation reactions. 相似文献
9.
Cobalt‐Catalyzed Tandem C−H Activation/C−C Cleavage/C−H Cyclization of Aromatic Amides with Alkylidenecyclopropanes 下载免费PDF全文
Dr. Mingliang Li Prof. Dr. Fuk Yee Kwong 《Angewandte Chemie (International ed. in English)》2018,57(22):6512-6516
A cobalt‐catalyzed chelation‐assisted tandem C?H activation/C?C cleavage/C?H cyclization of aromatic amides with alkylidenecyclopropanes is reported. This process allows the sequential formation of two C?C bonds, which is in sharp contrast to previous reports on using rhodium catalysts for the formation of C?N bonds. Here the inexpensive catalyst system exhibits good functional‐group compatibility and relatively broad substrate scope. The desired products can be easily transformed into polycyclic lactones with m‐CPBA. Mechanistic studies revealed that the tandem reaction proceeds through a C?H cobaltation, β‐carbon elimination, and intramolecular C?H cobaltation sequence. 相似文献
10.
Dr. Jose E. V. Valpuesta Dr. Eleuterio Álvarez Dr. Joaquín López‐Serrano Dr. Celia Maya Prof. Ernesto Carmona 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(41):13149-13159
The double C? H bond activation of a series of linear and cyclic ethers by the iridium complex [Tptol′Ir(C6H5)(N2)] ( 2? N2), which features a cyclometalated hydrotris(3‐p‐tolylpyrazol‐1‐yl)borate ligand (Tptol′) coordinated in a κ4‐N,N′,N′′,C manner, has been studied. Two methyl ethers, namely, Me2O and MeOtBu, along with diethyl ether and the cyclic ethers tetrahydrofuran, tetrahydropyran (THP), and 1,4‐dioxane have been investigated with formation in every case of the corresponding hydride carbene complexes 3 – 8 , which are stabilized by κ4‐coordination of the ancillary Tptol′ ligand. Five of the compounds have been structurally authenticated by X‐ray crystallography. A remarkable feature of these rearrangements is the reversibility of the double C? H bond activation of Me2O, MeOtBu, Et2O, and THP. This has permitted catalytic deuterium incorporation into the methyl groups of the two methyl ethers, although in a rather inefficient manner (for synthetic purposes). Although possible in all cases, C? C coupling by migratory insertion of the carbene into the Ir? C σ bond of the metalated linkage has only been observed for complex 8 that contains a cyclic carbene that results from α,α‐C? H activation of 1,4‐dioxane. Computational studies on the formation of iridium carbenes are also reported, which show a role for metalated Tp ligands in the double C? H activation and account for the reversibility of the reaction in terms of the relative stability of the reagents and the products of the reaction. 相似文献
11.
Wei‐Jun Kong Zhigao Shen Lars H. Finger Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2020,59(14):5551-5556
Nitrogen‐doped polycyclic aromatic hydrocarbons (aza‐PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza‐PAHs was developed via a rhodium‐catalyzed cascade C?H activation and alkyne annulation. A multifunctional O‐methylamidoxime enabled the high chemo‐ and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C?H activation steps. In addition, the metalla‐electrocatalyzed multiple C?H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups. 相似文献
12.
Hindered rotation in two o-substituted N,N-dimethylthiobenzamides was investigated by variable temperature 1H NMR spectroscopy. For one compound, the enthalpies and entropies of activation for (i) thioamide group rotation around the Ar? C bond and (ii) dimethylamino group rotation around the C? N bond were obtained by full line shape analysis; a possible coupling between the two processes is discussed. A new simple method has also been applied to the analysis of dimethylamino exchange and results are in complete agreement with the full line shape analysis with somewhat better precision. 相似文献
13.
Dr. Guy Rouquet Prof. Dr. Naoto Chatani 《Angewandte Chemie (International ed. in English)》2013,52(45):11726-11743
C? H bonds are ubiquitous in organic compounds. It would, therefore, appear that direct functionalization of substrates by activation of C? H bonds would eliminate the multiple steps and limitations associated with the preparation of functionalized starting materials. Regioselectivity is an important issue because organic molecules can contain a wide variety of C? H bonds. The use of a directing group can largely overcome the issue of regiocontrol by allowing the catalyst to come into proximity with the targeted C? H bonds. A wide variety of functional groups have been evaluated for use as directing groups in the transformation of C? H bonds. In 2005, Daugulis reported the arylation of unactivated C(sp3)? H bonds by using 8‐aminoquinoline and picolinamide as bidentate directing groups, with Pd(OAc)2 as the catalyst. Encouraged by these promising results, a number of transformations of C? H bonds have since been developed by using systems based on bidentate directing groups. In this Review, recent advances in this area are discussed. 相似文献
14.
Cui‐Yu Niu Jiao Jiao Bin Xing Gui‐Chang Wang Xian‐He Bu 《Journal of computational chemistry》2010,31(10):2023-2037
The decomposition mechanisms of methanol on five different Pt surfaces, the flat surface of Pt(111), Pt‐defect, Pt‐step, Pt(110)(1 × 1), and Pt(110)(2 × 1), have been studied with the DFT‐GGA method using the repeated slab model. The adsorption energies under the most stable configuration of the possible species and the activation energy barriers of the possible elementary reactions involved are obtained in this work. Through systematic calculations for the reaction mechanism of methanol decomposition on these surfaces, we found that such a reaction shows the same reaction mechanism on these Pt‐based model catalysts, that is, the final products are all H (Hads) and CO (COads) via O? H bond breaking in methanol and C? H bond scission in methoxy. These results are in general agreement with the previous experimental observations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010. 相似文献
15.
Palladium–N‐Heterocyclic Carbene (NHC)‐Catalyzed Asymmetric Synthesis of Indolines through Regiodivergent C(sp3)H Activation: Scope and DFT Study 下载免费PDF全文
Dmitry Katayev Dr. Evgeny Larionov Dr. Masafumi Nakanishi Dr. Céline Besnard Prof. Dr. E. Peter Kündig 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(46):15021-15030
Two bulky, chiral, monodentate N‐heterocyclic carbene ligands were applied to palladium‐catalyzed asymmetric C?H arylation to incorporate C(sp3)?H bond activation. Racemic mixtures of the carbamate starting materials underwent regiodivergent reactions to afford different trans‐2,3‐substituted indolines. Although this CAr?Calkyl coupling requires high temperatures (140–160 °C), chiral induction is high. This regiodivergent reaction, when carried out with enantiopure starting materials, can lead to single structurally different enantiopure products, depending on the catalyst chirality. The C?H activation at a tertiary center was realized only in the case of a cyclopropyl group. No C?H activation takes place alpha to a tertiary center. A detailed DFT study is included and analyses of methyl versus methylene versus methine C?H activation is used to rationalize experimentally observed regio‐ and enantioselectivities. 相似文献
16.
Nadine Kuhl Dr. Matthew N. Hopkinson Dr. Joanna Wencel‐Delord Prof. Dr. Frank Glorius 《Angewandte Chemie (International ed. in English)》2012,51(41):10236-10254
The use of coordinating moieties as directing groups for the functionalization of aromatic C? H bonds has become an established tool to enhance reactivity and induce regioselectivity. Nevertheless, with regard to the synthetic applicability of C? H activation, there is a growing interest in transformations in which the directing group can be fully abandoned, thus allowing the direct functionalization of simple benzene derivatives. However, this approach requires the disclosure of new strategies to achieve reactivity and to control selectivity. In this review, recent advances in the emerging field of non‐chelate‐assisted C? H activation are discussed, highlighting some of the most intriguing and inspiring examples of induction of reactivity and selectivity. 相似文献
17.
Synthesis of Dibenzo[c,e]oxepin‐5(7H)‐ones from Benzyl Thioethers and Carboxylic Acids: Rhodium‐Catalyzed Double CH Activation Controlled by Different Directing Groups 下载免费PDF全文
Xi‐Sha Zhang Yun‐Fei Zhang Zhao‐Wei Li Fei‐Xian Luo Prof. Dr. Zhang‐Jie Shi 《Angewandte Chemie (International ed. in English)》2015,54(18):5478-5482
A rhodium(III)‐catalyzed cross‐coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C? H, C? S, O? H) and the formation of two bonds (C? C, C? O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C? H activation, the first of such examples in cross‐oxidative coupling. 相似文献
18.
Enantioselective C−H Olefination of α‐Hydroxy and α‐Amino Phenylacetic Acids by Kinetic Resolution 下载免费PDF全文
Dr. Kai‐Jiong Xiao Ling Chu Prof. Dr. Jin‐Quan Yu 《Angewandte Chemie (International ed. in English)》2016,55(8):2856-2860
Significant progress has been made in the past decade regarding the development of enantioselective C?H activation reactions by desymmetrization. However, the requirement for the presence of two chemically identical prochiral C?H bonds represents an inherent limitation in scope. Reported is the first example of kinetic resolution by a palladium(II)‐catalyzed enantioselective C?H activation and C?C bond formation, thus significantly expanding the scope of enantioselective C?H activation reactions. 相似文献
19.
Iridium‐Catalyzed Synthesis of Diaryl Ethers by Means of Chemoselective CF Bond Activation and the Formation of BF Bonds 下载免费PDF全文
Jianping Chen Keyan Zhao Bingyang Ge Chongying Xu Dr. Dawei Wang Prof. Yuqiang Ding 《化学:亚洲杂志》2015,10(2):468-473
Transition‐metal‐catalyzed C? F activation, in comparison with C? H activation, is more difficult to achieve and therefore less fully understood, mainly because carbon–fluorine bonds are the strongest known single bonds to carbon and have been very difficult to cleave. Transition‐metal complexes are often more effective at cleaving stronger bonds, such as C(sp2)? X versus C(sp3)? X. Here, the iridium‐catalyzed C? F activation of fluorarenes was achieved through the use of bis(pinacolato)diboron with the formation of the B? F bond and self‐coupling. This strategy provides a convenient method with which to convert fluoride aromatic compounds into symmetrical diaryl ether compounds. Moreover, the chemoselective products of the C? F bond cleavage were obtained at high yields with the C? Br and C? Cl bonds remaining. 相似文献
20.
Rhodium(III)‐Catalyzed Selective ortho‐Olefinations of N‐Acyl and N‐Aroyl Sulfoximines by CH Bond Activation 下载免费PDF全文
Dr. Kanniyappan Parthasarathy Prof. Dr. Carsten Bolm 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(17):4896-4900
Two new rhodium‐catalyzed oxidative couplings between sulfoximine derivatives and alkenes by regioselective C?H activation, affording ortho‐olefinated (Heck‐type) products, are reported. A synthetic application of the ortho‐alkenylated products into the corresponding cyclic derivatives has been demonstrated, and a mechanistic rational for the rhodium catalysis is presented. 相似文献