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1.
Torben Rogge Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(44):15640-15645
Experimental and computational studies provide detailed insight into the selectivity‐ and reactivity‐controlling factors in bifurcated ruthenium‐catalyzed direct C?H arylations and dehydrogenative C?H/C?H functionalizations. Thorough investigations revealed the importance of arene‐ligand‐free complexes for the formation of biscyclometalated intermediates within a ruthenium(II/IV/II) mechanistic manifold. 相似文献
2.
Pd‐catalyzed oxidative coupling reaction was of great importance in the aromatic C? H activation and the formation of new C? O and C? C bonds. Sanford has pioneered practical, directed C? H activation reactions employing Pd(OAc)2 as catalyst since 2004. However, until now, the speculated reactive Pd(IV) transient intermediates in these reactions have not been isolated or directly detected from reaction solution. Electrospray ionization tandem mass spectrometry (ESI‐MS/MS) was used to intercept and characterize the reactive Pd(IV) transient intermediates in the solutions of Pd(OAc)2‐catalyzed oxidative coupling reactions. In this study, the Pd(IV) transient intermediates were detected from the solution of Pd(OAc)2‐catalyzed oxidative coupling reactions by ESI‐MS and the MS/MS of the intercepted Pd(IV) transient intermediate in reaction system was the same with the synthesized authentic Pd(IV) complex. Our ESI‐MS(/MS) studies confirmed the presence of Pd(IV) reaction transient intermediates. Most interestingly, the MS/MS of Pd(IV) transient intermediates showed the reductive elimination reactivity to Pd(II) complexes with new C? O bond formation into product in gas phase, which was consistent with the proposed reactivity of the Pd(IV) transient intermediates in solution. 相似文献
3.
Mlanie M. Lorion Nikolaos Kaplaneris Jongwoo Son Rositha Kuniyil Lutz Ackermann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1698-1702
Bioorthogonal late‐stage diversification of structurally complex peptides has enormous potential for drug discovery and molecular imaging. In recent years, transition‐metal‐catalyzed C?H activation has emerged as an increasingly viable tool for peptide modification. Despite major accomplishments, these strategies largely rely on expensive palladium catalysts. We herein report an unprecedented cobalt(III)‐catalyzed peptide C?H activation, which enables the direct C?H functionalization of structurally complex peptides, and sets the stage for a multicatalytic C?H activation/alkene metathesis/hydrogenation strategy for the assembly of novel cyclic peptides. 相似文献
4.
Jiayu Mo Thomas Müller Joo C. A. Oliveira Serhiy Demeshko Franc Meyer Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2019,58(37):12874-12878
An iron‐catalyzed C?H/N?H alkyne annulation was realized by using a customizable clickable triazole amide under exceedingly mild reaction conditions. A unifying mechanistic approach combining experiment, spectroscopy, kinetics, and computation provided strong support for facile C?H activation by a ligand‐to‐ligand hydrogen transfer (LLHT) mechanism. Combined Mössbauer spectroscopic analysis and DFT calculations were indicative of high‐spin iron(II) species as the key intermediates in the C?H activation manifold. 相似文献
5.
Daniel Zell Qingqing Bu Dr. Milica Feldt Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2016,55(26):7408-7412
Cationic cobalt complexes enable unprecedented cobalt‐catalyzed C?H/C?C functionalizations with unique selectivity features. The versatile cobalt catalyst proved broadly applicable, enabled efficient C?H/C?C cleavage at room temperature, and delivered Z‐alkenes with excellent diastereocontrol. 相似文献
6.
Guangying Tan Shuang He Xiaolei Huang Xingrong Liao Yangyang Cheng Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2016,55(35):10414-10418
The first example of cobalt‐catalyzed oxidative C?H/C?H cross‐coupling between two heteroarenes is reported, which exhibits a broad substrate scope and a high tolerance level for sensitive functional groups. When the amount of Co(OAc)2?4 H2O is reduced from 6.0 to 0.5 mol %, an excellent yield is still obtained at an elevated temperature with a prolonged reaction time. The method can be extended to the reaction between an arene and a heteroarene. It is worth noting that the Ag2CO3 oxidant is renewable. Preliminary mechanistic studies by radical trapping experiments, hydrogen/deuterium exchange experiments, kinetic isotope effect, electron paramagnetic resonance (EPR), and high resolution mass spectrometry (HRMS) suggest that a single electron transfer (SET) pathway is operative, which is distinctly different from the dual C?H bond activation pathway that the well‐described oxidative C?H/C?H cross‐coupling reactions between two heteroarenes typically undergo. 相似文献
7.
Cobalt‐Catalyzed sp2‐C−H Activation: Intermolecular Heterocyclization with Allenes at Room Temperature
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Dr. Neetipalli Thrimurtulu Arnab Dey Prof. Debabrata Maiti Prof. Chandra M. R. Volla 《Angewandte Chemie (International ed. in English)》2016,55(40):12361-12365
The reactivity of allenes in transition‐metal‐catalyzed C?H activation chemistry is governed by the formation of either alkenyl–metal (M–alkenyl) or metal–π‐allyl intermediates. Although either protonation or a β‐hydride elimination is feasible with a M–alkenyl intermediate, cyclization has remained unexplored to date. Furthermore, due to the increased steric hindrance, the regioselectivity for the intramolecular cyclization of the metal–π‐allyl intermediate was hampered towards the more substituted side. To address these issues, a unified approach to synthesize a diverse array of biologically and pharmaceutically relevant heterocyclic moieties by cobalt‐catalyzed directed C?H functionalization was envisioned. Upon successful implementation, the present strategy led to the regioselective formation of dihydroisoquinolin‐1(2H)‐ones, isoquinolin‐1(2H)‐ones, dihydropyridones, and pyridones. 相似文献
8.
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
9.
Mononuclear Nonheme High‐Spin (S=2) versus Intermediate‐Spin (S=1) Iron(IV)–Oxo Complexes in Oxidation Reactions
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Seong Hee Bae Dr. Mi Sook Seo Dr. Yong‐Min Lee Dr. Kyung‐Bin Cho Prof. Dr. Won‐Suk Kim Prof. Dr. Wonwoo Nam 《Angewandte Chemie (International ed. in English)》2016,55(28):8027-8031
Mononuclear nonheme high‐spin (S=2) iron(IV)–oxo species have been identified as the key intermediates responsible for the C?H bond activation of organic substrates in nonheme iron enzymatic reactions. Herein we report that the C?H bond activation of hydrocarbons by a synthetic mononuclear nonheme high‐spin (S=2) iron(IV)–oxo complex occurs through an oxygen non‐rebound mechanism, as previously demonstrated in the C?H bond activation by nonheme intermediate (S=1) iron(IV)–oxo complexes. We also report that C?H bond activation is preferred over C=C epoxidation in the oxidation of cyclohexene by the nonheme high‐spin (HS) and intermediate‐spin (IS) iron(IV)–oxo complexes, whereas the C=C double bond epoxidation becomes a preferred pathway in the oxidation of deuterated cyclohexene by the nonheme HS and IS iron(IV)–oxo complexes. In the epoxidation of styrene derivatives, the HS and IS iron(IV) oxo complexes are found to have similar electrophilic characters. 相似文献
10.
Minghui Zhou Marianne Lankelma Jarl Ivar van der Vlugt Bas de Bruin 《Angewandte Chemie (International ed. in English)》2020,59(27):11073-11079
The metalloradical activation of o‐aryl aldehydes with tosylhydrazide and a cobalt(II) porphyrin catalyst produces cobalt(III)‐carbene radical intermediates, providing a new and powerful strategy for the synthesis of medium‐sized ring structures. Herein we make use of the intrinsic radical‐type reactivity of cobalt(III)‐carbene radical intermediates in the [CoII(TPP)]‐catalyzed (TPP=tetraphenylporphyrin) synthesis of two types of 8‐membered ring compounds; novel dibenzocyclooctenes and unprecedented monobenzocyclooctadienes. The method was successfully applied to afford a variety of 8‐membered ring compounds in good yields and with excellent substituent tolerance. Density functional theory (DFT) calculations and experimental results suggest that the reactions proceed via hydrogen atom transfer from the bis‐allylic/benzallylic C?H bond to the carbene radical, followed by two divergent processes for ring‐closure to the two different types of 8‐membered ring products. While the dibenzocyclooctenes are most likely formed by dissociation of o‐quinodimethanes (o‐QDMs) which undergo a non‐catalyzed 8π‐cyclization, DFT calculations suggest that ring‐closure to the monobenzocyclooctadienes involves a radical‐rebound step in the coordination sphere of cobalt. The latter mechanism implies that unprecedented enantioselective ring‐closure reactions to chiral monobenzocyclooctadienes should be possible, as was confirmed for reactions mediated by a chiral cobalt‐porphyrin catalyst. 相似文献
11.
Cobalt‐Catalyzed Tandem C−H Activation/C−C Cleavage/C−H Cyclization of Aromatic Amides with Alkylidenecyclopropanes
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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
12.
Can Li Zheng Yang Lei Wang Yinlong Guo Zheng Huang Shengming Ma 《Angewandte Chemie (International ed. in English)》2020,59(15):6278-6283
An efficient pincer‐ligand‐based cobalt‐complex‐catalyzed allene hydroboration affording Z‐allylic boronates is described. The reaction demonstrates an excellent regio‐ as well as Z‐stereoselectivity and a wide substrate scope that tolerates many functional groups. Based on solvent‐assisted electrospray ionization mass spectrometry (SAESI‐MS) studies, a rationale for the cobalt‐catalyzed hydroboration involving the highly selective insertion of an allene into the Co?H bond to form Z‐allylic cobalt intermediates is proposed. 相似文献
13.
Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt‐Catalyzed C−H Activation and Intramolecular Nucleophilic Addition
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Dr. Parthasarathy Gandeepan Dr. Pachaiyappan Rajamalli Prof. Dr. Chien‐Hong Cheng 《Angewandte Chemie (International ed. in English)》2016,55(13):4308-4311
A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt‐catalyzed C?H activation and intramolecular nucleophilic addition to the amide functional group. Transition‐metal‐catalyzed C?H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C?H bond cleavage may be the rate‐limiting step. 相似文献
14.
Cobalt‐Catalyzed Oxidative Annulation of Nitrogen‐Containing Arenes with Alkynes: An Atom‐Economical Route to Heterocyclic Quaternary Ammonium Salts
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Sekar Prakash Dr. Krishnamoorthy Muralirajan Prof. Dr. Chien‐Hong Cheng 《Angewandte Chemie (International ed. in English)》2016,55(5):1844-1848
Four cobalt‐catalyzed oxidative annulation reactions of nitrogen‐containing arenes with alkynes proceeds by C?H activation, thus leading to biologically useful quaternary ammonium salts, including pyridoisoquinolinium, cinnolinium, isoquinolinium, and quinolizinium salts, in high yields. The results are comparable to those reactions catalyzed by rhodium and ruthenium complexes. The transformation of the salts into various N‐heterocycles has also been demonstrated. 相似文献
15.
Manganese‐Catalyzed Dehydrogenative [4+2] Annulation of NH Imines and Alkynes by CH/NH Activation
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Ruoyu He Prof. Dr. Zhi‐Tang Huang Prof. Dr. Qi‐Yu Zheng Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2014,53(19):4950-4953
Described herein is a manganese‐catalyzed dehydrogenative [4+2] annulation of N? H imines and alkynes, a reaction providing highly atom‐economical access to diverse isoquinolines. This transformation represents the first example of manganese‐catalyzed C? H activation of imines; the stoichiometric variant of the cyclomanganation was reported in 1971. The redox neutral reaction produces H2 as the major byproduct and eliminates the need for any oxidants, external ligands, or additives, thus standing out from known isoquinoline synthesis by transition‐metal‐catalyzed C? H activation. Mechanistic studies revealed the five‐membered manganacycle and manganese hydride species as key reaction intermediates in the catalytic cycle. 相似文献
16.
Cobalt‐Catalyzed CH Arylations with Weakly‐Coordinating Amides and Tetrazoles: Expedient Route to Angiotensin‐II‐Receptor Blockers
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Jie Li Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5718-5722
Cobalt‐catalyzed C?H arylations enabled the synthesis of biaryl tetrazoles, which are key structural motifs in antihypertensive angiotensin‐II‐receptor blockers. Thus, weakly‐coordinating benzamides were employed for step‐economical C?H arylations with ample scope. Further, a low‐valent NHC complex enabled first cobalt‐catalyzed C?H functionalization by tetrazole assistance. 相似文献
17.
Cobalt(III)‐Catalyzed Intramolecular Cross‐Dehydrogenative C−H/X−H Coupling: Efficient Synthesis of Indoles and Benzofurans
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Jayanta Ghorai Angula Chandra Shekar Reddy Prof. Dr. Pazhamalai Anbarasan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(45):16042-16046
An efficient cobalt(III)‐catalyzed intramolecular cross‐dehydrogenative C?H/N?H coupling of ortho‐alkenylanilines has been developed utilizing O2 as a terminal oxidant. The developed reaction tolerates various reactive functional groups and allows the synthesis of diverse indole derivatives in good to excellent yields. The method was successfully extended to the synthesis of benzofurans through the intramolecular cross‐dehydrogenative C?H/O?H coupling of ortho‐alkenylphenols. 相似文献
18.
Overcoming the Limitations of C−H Activation with Strongly Coordinating N‐Heterocycles by Cobalt Catalysis
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Hui Wang Dr. Mélanie M. Lorion Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2016,55(35):10386-10390
Strongly coordinating nitrogen heterocycles, including pyrimidines, oxazolines, pyrazoles, and pyridines, were fully tolerated in cobalt‐catalyzed C?H amidations by imidate assistance. Structurally complex quinazolines are thus accessible in a step‐economic manner. Our findings also establish the relative powers of directing groups in cobalt(III)‐catalyzed C?H functionalization for the first time. 相似文献
19.
Palladium‐Catalyzed/Norbornene‐Mediated CH Activation/ N‐Tosylhydrazone Insertion Reaction: A Route to Highly Functionalized Vinylarenes
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Dr. Ping‐Xin Zhou Lan Zheng Jun‐Wei Ma Yu‐Ying Ye Xue‐Yuan Liu Prof. Dr. Peng‐Fei Xu Prof. Dr. Yong‐Min Liang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(22):6745-6751
A straightforward method for the synthesis of highly functionalized vinylarenes through palladium‐catalyzed, norbornene‐mediated C?H activation/carbene migratory insertion is described. Extension to a one‐pot procedure is also developed. Furthermore, this method can also be used to generate polysubstituted bicyclic molecules. The reaction proceeds under mild conditions to give the products in satisfactory yields using readily available starting materials. This is a Catellani–Lautens reaction that incorporates different types of coupling partners. Additionally, this reaction is the first to demonstrate the possibility of combining Pd‐catalyzed insertion of diazo compounds and Pd‐catalyzed C?H activation. 相似文献
20.
The CH Activation/1,3‐Diyne Strategy: Highly Selective Direct Synthesis of Diverse Bisheterocycles by RhIII Catalysis
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Dr. Da‐Gang Yu Francisco de Azambuja Tobias Gensch Dr. Constantin G. Daniliuc Prof. Dr. Frank Glorius 《Angewandte Chemie (International ed. in English)》2014,53(36):9650-9654
The reactivity and selectivity of 1,3‐diynes in transition‐metal‐catalyzed C? H activation is exploited to quickly assemble diverse polysubstituted bisheterocycles, which are highly important but difficult to access. By using the C? H activation/1,3‐diyne strategy, we overcame the challenges of selectivity (chemo‐, regio‐, and mono‐/diannulation) and constructed seven kinds of adjacent bisheterocycles through the formation of four strategic bonds with high efficiency and high selectivity. 相似文献