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1.
Ruthenium(II)‐Catalyzed Traceless C−H Functionalization Using an N−N Bond as an Internal Oxidant 下载免费PDF全文
Dr. Shuguang Zhou Jinhu Wang Pei Chen Kehao Chen Prof. Dr. Jin Zhu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(41):14508-14512
A previously elusive RuII‐catalyzed N?N bond‐based traceless C?H functionalization strategy is reported. An N‐amino (i.e., hydrazine) group is used for the directed C?H functionalization with either an alkyne or an alkene, affording an indole derivative or olefination product. The synthesis features a broad substrate scope, superior atom and step economy, as well as mild reaction conditions. 相似文献
2.
Iron‐Carbonyl‐Catalyzed Redox‐Neutral [4+2] Annulation of N−H Imines and Internal Alkynes by C−H Bond Activation 下载免费PDF全文
Teng Jia Chongyang Zhao Dr. Ruoyu He Prof. Dr. Hui Chen Prof. Dr. Congyang Wang 《Angewandte Chemie (International ed. in English)》2016,55(17):5268-5271
Stoichiometric C?H bond activation of arenes mediated by iron carbonyls was reported by Pauson as early as in 1965, yet the catalytic C?H transformations have not been developed. Herein, an iron‐catalyzed annulation of N?H imines and internal alkynes to furnish cis‐3,4‐dihydroisoquinolines is described, and represents the first iron‐carbonyl‐catalyzed C?H activation reaction of arenes. Remarkablely, this is also the first redox‐neutral [4+2] annulation of imines and alkynes proceeding by C?H activation. The reaction also features only cis stereoselectivity and excellent atom economy as neither base, nor external ligand, nor additive is required. Experimental and theoretical studies reveal an oxidative addition mechanism for C?H bond activation to afford a dinuclear ferracycle and a synergetic diiron‐promoted H‐transfer to the alkyne as the turnover‐determining step. 相似文献
3.
Dr. Youai Qiu Cong Tian Leonardo Massignan Torben Rogge Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(20):5818-5822
Electrocatalysis has been identified as a powerful strategy for organometallic catalysis, and yet electrocatalytic C?H activation is restricted to strongly N‐coordinating directing groups. The first example of electrocatalytic C?H activation by weak O‐coordination is presented, in which a versatile ruthenium(II) carboxylate catalyst enables electrooxidative C?H/O?H functionalization for alkyne annulations in the absence of metal oxidants; thereby exploiting sustainable electricity as the sole oxidant. Mechanistic insights provide strong support for a facile organometallic C?H ruthenation and an effective electrochemical reoxidation of the key ruthenium(0) intermediate. 相似文献
4.
Cuiju Zhu Rositha Kuniyil Lutz Ackermann 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(16):5392-5396
Complexity‐increasing Domino reactions comprising C?H allenylation, a Diels–Alder reaction, and a retro‐Diels–Alder reaction were realized by a versatile catalyst derived from earth‐abundant, non‐toxic manganese. The C?H activation/Diels–Alder/retro‐Diels–Alder alkyne annulation sequence provided step‐economical access to valuable indolone alkaloid derivatives through a facile organometallic C?H activation manifold with transformable pyridines. 相似文献
5.
Distal Weak Coordination of Acetamides in Ruthenium(II)‐Catalyzed C−H Activation Processes 下载免费PDF全文
Qingqing Bu Torben Rogge Dr. Vladislav Kotek Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(3):765-768
C?H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C?H functionalization offers ample scope—including twofold oxidative C?H functionalizations and alkyne hydroarylations—through facile base‐assisted internal electrophilic‐type substitution (BIES) C?H ruthenation by weak O‐coordination. 相似文献
6.
1,4‐Iron Migration for Expedient Allene Annulations through Iron‐Catalyzed C−H/N−H/C−O/C−H Functionalizations 下载免费PDF全文
Jiayu Mo Thomas Müller Dr. João C. A. Oliveira Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(26):7719-7723
C?H activation bears great potential for enabling sustainable molecular syntheses in a step‐ and atom‐economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C?H/N?H/C?O/C?H functionalization sequence. The powerful iron catalysis occurred under external‐oxidant‐free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4‐iron migration regime for facile C?H activations. 相似文献
7.
Zhong‐Jian Cai Chen‐Xu Liu Qing Gu Chao Zheng Shu‐Li You 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(7):2171-2175
Asymmetric C?H bond functionalization reaction is one of the most efficient and straightforward methods for the synthesis of optically active molecules. Herein we disclose an asymmetric C?H/C?H cross‐coupling reaction of ferrocenes with azoles such as oxazoles and thiazoles. Palladium(II)/monoprotected amino acid (MPAA) catalytic system which exhibits excellent reactivity and regioselectivity for oxazoles and thiazoles. This method offers a powerful strategy for constructing planar chiral ferrocenes. Mechanistic studies suggest that the C?H bond cleavage of azoles is likely proceeding through a SEAr process and may not be a turnover limiting step. 相似文献
8.
Site‐Selective Remote Radical C−H Functionalization of Unactivated C−H Bonds in Amides Using Sulfone Reagents 下载免费PDF全文
Dr. Yong Xia Lin Wang Prof. Dr. Armido Studer 《Angewandte Chemie (International ed. in English)》2018,57(39):12940-12944
A general and practical strategy for remote site‐selective functionalization of unactivated aliphatic C?H bonds in various amides by radical chemistry is introduced. C?H bond functionalization is achieved by using the readily installed N‐allylsulfonyl moiety as an N‐radical precursor. The in situ generated N‐radical engages in intramolecular 1,5‐hydrogen atom transfer to generate a translocated C radical which is subsequently trapped with various sulfone reagents to afford the corresponding C?H functionalized amides. The generality of the approach is documented by the successful remote C?N3, C?Cl, C?Br, C?SCF3, C?SPh, and C?C bond formation. Unactivated tertiary and secondary C?H bonds, as well as activated primary C?H bonds, can be readily functionalized by this method. 相似文献
9.
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
10.
Oxidative C−H/C−H Cross‐Coupling Reactions between N‐Acylanilines and Benzamides Enabled by a Cp*‐Free RhCl3/TFA Catalytic System 下载免费PDF全文
Yang Shi Luoqiang Zhang Prof. Dr. Jingbo Lan Min Zhang Fulin Zhou Wenlong Wei Prof. Dr. Jingsong You 《Angewandte Chemie (International ed. in English)》2018,57(29):9108-9112
By making use of a dual‐chelation‐assisted strategy, a completely regiocontrolled oxidative C?H/C?H cross‐coupling reaction between an N‐acylaniline and a benzamide has been accomplished for the first time. This process constitutes a step‐economic and highly efficient pathway to 2‐amino‐2′‐carboxybiaryl scaffolds from readily available substrates. A Cp*‐free RhCl3/TFA catalytic system was developed to replace the [Cp*RhCl2]2/AgSbF6 system generally used in oxidative C?H/C?H cross‐coupling reactions between two (hetero)arenes (Cp*=pentamethylcyclopentadienyl, TFA=trifluoroacetic acid). The RhCl3/TFA system avoids the use of the expensive Cp* ligand and AgSbF6. As an illustrative example, the procedure developed herein greatly streamlines the total synthesis of the naturally occurring benzo[c]phenanthridine alkaloid oxynitidine, which was accomplished in excellent overall yield. 相似文献
11.
Nicolas Sauermann Dr. Ruhuai Mei Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(18):5090-5094
Syntheses of substituted anilines primarily rely on palladium‐catalyzed coupling chemistry with prefunctionalized aryl electrophiles. While oxidative aminations have emerged as powerful alternatives, they largely produce undesired metal‐containing by‐products in stoichiometric quantities. In contrast, described herein is the unprecedented electrochemical C?H amination by cobalt‐catalyzed C?H activation. The environmentally benign electrocatalysis avoids stoichiometric metal oxidants, can be conducted under ambient air, and employs a biomass‐derived, renewable solvent for sustainable aminations in an atom‐ and step‐economical manner with H2 as the sole byproduct. 相似文献
12.
Palladium/Norbornene‐Catalyzed C−H Alkylation/Alkyne Insertion/Indole Dearomatization Domino Reaction: Assembly of Spiroindolenine‐Containing Pentacyclic Frameworks 下载免费PDF全文
Lu Bai Jingjing Liu Wenjie Hu Kunyu Li Prof. Dr. Yaoyu Wang Prof. Dr. Xinjun Luan 《Angewandte Chemie (International ed. in English)》2018,57(18):5151-5155
Reported is a highly chemoselective intermolecular annulation of indole‐based biaryls with bromoalkyl alkynes by using palladium/norbornene (Pd/NBE) cooperative catalysis. This reaction is realized through a sequence of Catellani‐type C?H alkylation, alkyne insertion, and indole dearomatization, by forming two C(sp2)?C(sp3) and one C(sp2)?C(sp2) bonds in a single chemical operation, thus providing a diverse range of pentacyclic molecules, containing a spiroindolenine fragment, in good yields with excellent functional‐group tolerance. Preliminary mechanistic studies reveal that C?H bond cleavage is likely involved in the rate‐determining step, and the indole dearomatization might take place through an olefin coordination/insertion and β‐hydride elimination Heck‐type pathway. 相似文献
13.
An Enantioselective Bidentate Auxiliary Directed Palladium‐Catalyzed Benzylic C−H Arylation of Amines Using a BINOL Phosphate Ligand 下载免费PDF全文
Hao Wang Hua‐Rong Tong Prof. Dr. Gang He Prof. Dr. Gong Chen 《Angewandte Chemie (International ed. in English)》2016,55(49):15387-15391
A new enantioselective palladium(II)‐catalyzed benzylic C?H arylation reaction of amines is enabled by the bidentate picolinamide (PA) directing group. This reaction provides the first example of enantioselective benzylic γ‐C?H arylations of alkyl amines, and proceeds with up to 97 % ee. The 2,2′‐dihydroxy‐1,1′‐binaphthyl (BINOL) phosphoric acid ligand, Cs2CO3, and solvent‐free conditions are essential for high enantioselectivity. Mechanistic studies suggest that multiple BINOL ligands are involved in the stereodetermining C?H palladation step. 相似文献
14.
C?C triple bonds are amongst the most versatile functional groups in synthetic chemistry. Complementary to the Sonogashira coupling the direct metal‐catalyzed alkynylation of C?H bonds has emerged as a highly promising approach in recent years. To guarantee a high regioselectivity suitable directing groups (DGs) are necessary to guide the transition metal (TM) into the right place. In this Focus Review we present the current developments in DG‐mediated C(sp2)?H and C(sp3)?H modifications with terminal alkynes under oxidative conditions and with electrophilic alkynylation reagents. We will discuss further modifications of the alkyne, in particular subsequent cyclizations to carbo‐ and heterocycles and modifications of the DG in the presence of the alkyne. 相似文献
15.
Nickel‐Catalyzed Oxidative C−H/N−H Isocyanide Insertion: An Efficient Synthesis of Iminoisoindolinone Derivatives 下载免费PDF全文
Dr. Wenyan Hao Jun Tian Dr. Wu Li Renyi Shi Zhiliang Huang Prof. Aiwen Lei 《化学:亚洲杂志》2016,11(11):1664-1667
Transition metal‐catalyzed isocyanide insertion has served as a fundamental and important chemical transformation. Classical isocyanide insertion usually occurs between organohalides and nucleophiles, which normally involves tedious and non‐atom‐economical prefunctionalization processes. However, oxidative C?H/N?H isocyanide insertion offers an efficient and green alternative. Herein, a nickel‐catayzed oxidative C?H/N?H isocyanide insertion of aminoquinoline benzamides has been developed. Different kinds of iminoisoindolinone derivatives could be synthesized in good yields by utilizing Ni(acac)2 as the catalyst. In this transformation, isocyanide serves as an efficient C1 connector, which further inserted into two simple nucleophiles (C?H/N?H), representing an effective way to construct heterocycles. 相似文献
16.
Direct Synthesis of Protoberberine Alkaloids by Rh‐Catalyzed C−H Bond Activation as the Key Step 下载免费PDF全文
Dr. Jayachandran Jayakumar Prof. Dr. Chien‐Hong Cheng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(5):1800-1804
A one‐pot reaction of substituted benzaldehydes with alkyne–amines by a Rh‐catalyzed C?H activation and annulation to afford various natural and unnatural protoberberine alkaloids is reported. This reaction provides a convenient route for the generation of a compound library of protoberberine salts, which recently have attracted great attention because of their diverse biological activities. In addition, pyridinium salt derivatives can also be formed in good yields from α,β‐unsaturated aldehydes and amino–alkynes. This reaction proceeds with excellent regioselectivity and good functional group compatibility under mild reaction conditions by using O2 as the oxidant. 相似文献
17.
Mixed Directing‐Group Strategy: Oxidative C−H/C−H Bond Arylation of Unactivated Arenes by Cobalt Catalysis 下载免费PDF全文
Cong Du Peng‐Xiang Li Dr. Xinju Zhu Jian‐Feng Suo Dr. Jun‐Long Niu Prof. Mao‐Ping Song 《Angewandte Chemie (International ed. in English)》2016,55(43):13571-13575
A mixed directing‐group strategy for inexpensive [Co(acac)3]‐catalyzed oxidative C?H/C?H bond arylation of unactivated arenes has been disclosed. This strategy enables the arylation of a wide range of benzamide and arylpyridines effectively to afford novel bifunctionalized biaryls, which are difficult to achieve by common synthetic routes. Two different pathways, namely, a single‐electron‐transmetalation process (8‐aminoquinoline‐directed) and a concerted metalation–deprotonation process (pyridine‐directed), were involved to activate two different inert aromatic C?H bonds. Moreover, the aryl radicals have been trapped by 2,6‐di‐tert‐butyl‐4‐methylphenol to form benzylated products. This unique strategy should be useful in the design of other arene C?H/C?H cross‐couplings as well. 相似文献
18.
A DFT Study on the Conversion of Aryl Iodides to Alkyl Iodides: Reductive Elimination of R−I from Alkylpalladium Iodide Complexes with Accessible β‐Hydrogens 下载免费PDF全文
Wei Hao Junnian Wei Yue Chi Prof. Dr. Patrick J. Walsh Prof. Dr. Zhenfeng Xi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3422-3429
DFT calculations have been performed on the palladium‐catalyzed carboiodination reaction. The reaction involves oxidative addition, alkyne insertion, C?N bond cleavage, and reductive elimination. For the alkylpalladium iodide intermediate, LiOtBu stabilizes the intermediate in non‐polar solvents, thus promoting reductive elimination and preventing β‐hydride elimination. The C?N bond cleavage process was explored and the computations show that PPh3 is not bound to the Pd center during this step. Experimentally, it was demonstrated that LiOtBu is not necessary for the oxidative addition, alkyne insertion, or C?N bond cleavage steps, lending support to the conclusions from the DFT calculations. The turnover‐limiting steps were found to be C?N bond cleavage and reductive elimination, whereas oxidative addition, alkyne insertion, and formation of the indole ring provide the driving force for the reaction. 相似文献
19.
Thomas Müller Prof. Dr. Lutz Ackermann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14151-14154
The C?H thiolation of aniline derivatives was accomplished with a versatile nickel(II) catalyst under ligand‐free conditions. The robust nature of the nickel catalysis system was reflected by the C?H thiolation with a good functional group tolerance and an ample scope, employing anilines possessing removable directing groups. The widely applicable nickel catalyst also allowed for aniline C?H selenylations, while mechanistic studies provided strong support that the rate‐determining step is the C?H activation. 相似文献
20.
Electrooxidative Rhodium‐Catalyzed C−H/C−H Activation: Electricity as Oxidant for Cross‐Dehydrogenative Alkenylation 下载免费PDF全文
Dr. Youai Qiu Dr. Wei‐Jun Kong Julia Struwe Nicolas Sauermann Torben Rogge Alexej Scheremetjew Prof. Dr. Lutz Ackermann 《Angewandte Chemie (International ed. in English)》2018,57(20):5828-5832
Rhodium(III) catalysis has enabled a plethora of oxidative C?H functionalizations, which predominantly employ stoichiometric amounts of toxic and/or expensive metal oxidants. In contrast, we herein describe the first electrochemical rhodium‐catalyzed C?H activation that avoids hazardous chemical oxidants. Environmentally benign twofold C?H/C?H functionalizations were accomplished with weakly coordinating benzoic acids and benzamides, employing electricity as the terminal oxidant and generating H2 as the sole byproduct. 相似文献