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1.
Prashi Jain Shuyan Yi Patrick Thomas Flaherty 《Journal of heterocyclic chemistry》2013,50(Z1):E166-E173
This article focuses on the utility of organotrifluoroborate salts as coupling partners for Suzuki–Miyaura cross‐coupling with 4‐nitro‐6‐triflyl benzimidazoles using microwave irradiation. The C–C bond formation at the 6‐position of the electron‐rich 1‐,4‐,6‐trisubstituted benzimidazole core is challenging and was not achievable via Kumada, Negishi, Stille, or Heck coupling strategies. Yields of 37–70% could be obtained via palladium coupling strategies utilizing potassium benzyl trifluoroborates as the organometallic coupling partner. 相似文献
2.
Synthesis of All‐Carbon Disubstituted Bicyclo[1.1.1]pentanes by Iron‐Catalyzed Kumada Cross‐Coupling
Jeremy Nugent Bethany R. Shire Dimitri F. J. Caputo Helena D. Pickford Frank Nightingale Ian T. T. Houlsby James J. Mousseau Edward A. Anderson 《Angewandte Chemie (International ed. in English)》2020,59(29):11866-11870
1,3‐Disubstituted bicyclo[1.1.1]pentanes (BCPs) are important motifs in drug design as surrogates for p‐substituted arenes and alkynes. Access to all‐carbon disubstituted BCPs via cross‐coupling has to date been limited to use of the BCP as the organometallic component, which restricts scope due to the harsh conditions typically required for the synthesis of metallated BCPs. Here we report a general method to access 1,3‐C‐disubstituted BCPs from 1‐iodo‐bicyclo[1.1.1]pentanes (iodo‐BCPs) by direct iron‐catalyzed cross‐coupling with aryl and heteroaryl Grignard reagents. This chemistry represents the first general use of iodo‐BCPs as electrophiles in cross‐coupling, and the first Kumada coupling of tertiary iodides. Benefiting from short reaction times, mild conditions, and broad scope of the coupling partners, it enables the synthesis of a wide range of 1,3‐C‐disubstituted BCPs including various drug analogues. 相似文献
3.
Electrochemical Initiated C‐N Coupling of 3‐Methylcatechol and n‐Hexylamine in a Flow Cell Monitored with ESI‐MS
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The electrochemical initiated heterocoupling of 3‐methylcatechol and n‐hexylamine was investigated. The oxidation of 3‐methylcatechol was performed in an electrochemical flow cell with glassy carbon as the working electrode. As a result, the two‐electron, two‐proton oxidised chinone intermediate undergoes a C‐N coupling reaction in the presence of an amine (Michael addition). This mono coupling product can undergo a second two‐electron, two‐proton oxidation depending on acidic or basic conditions and substrate ratios. This flow cell was coupled on‐line with electrospray ionisation mass spectrometry to identify the possible coupling products. Higher substrate concentrations were performed off‐line as first scale‐up experiments in a two‐step procedure. 相似文献
4.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(2):564-568
We describe iron‐catalyzed intermolecular oxidative coupling reactions of diarylamines to form substituted 2,2′‐bis(arylamino)biaryl compounds, tetraarylhydrazines, and 5,6‐dihydrobenzo[c ]cinnolines with the same hexadecafluorinated iron–phthalocyanine catalyst. The mild formation of C−C or N−N bonds was controlled by the use of acidic or basic additives. In contrast to most iron‐catalyzed dehydrogenative coupling reactions, ambient air could be used as the sole oxidant. Moreover, iron(III) chloride hexahydrate promoted a one‐pot coupling and subsequent intramolecular dearomative coupling to give 10H ‐spiro[acridine‐9,1′‐cyclohexa‐2′,5′‐dien‐4′‐ones]. 相似文献
5.
Source of Selectivity in Oxidative Cross‐Coupling of Aryls by Solvent Effect of 1,1,1,3,3,3‐Hexafluoropropan‐2‐ol
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Dr. Bernd Elsler Anton Wiebe Dr. Dieter Schollmeyer Dr. Katrin M. Dyballa Prof. Dr. Robert Franke Prof. Dr. Siegfried R. Waldvogel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(35):12321-12325
Solvents such as 1,1,1,3,3,3‐hexafluoroisopropanol (HFIP) with a high capacity for donating hydrogen bonds generate solvates that enter into selective cross‐coupling reactions of aryls upon oxidation. When electric current is employed for oxidation, reagent effects can be excluded and a decoupling of nucleophilicity from oxidation potential can be achieved. The addition of water or methanol to the electrolyte allows a shift of oxidation potentials in a specific range, creating suitable systems for selective anodic cross‐coupling reactions. The shift in the redox potentials depends on the substitution pattern of the substrate employed. The concept has been expanded from arene–phenol to phenol–phenol as well as phenol–aniline cross‐coupling. This driving force for selectivity in oxidative coupling might also explain previous findings using HFIP and hypervalent iodine reagents. 相似文献
6.
Joseph Becica Oliver R. J. Heath Cameron H. M. Zheng David C. Leitch 《Angewandte Chemie (International ed. in English)》2020,59(39):17277-17281
Carboxylate esters have many desirable features as electrophiles for catalytic cross‐coupling: they are easy to access, robust during multistep synthesis, and mass‐efficient in coupling reactions. Alkenyl carboxylates, a class of readily prepared non‐aromatic electrophiles, remain difficult to functionalize through cross‐coupling. We demonstrate that Pd catalysis is effective for coupling electron‐deficient alkenyl carboxylates with arylboronic acids in the absence of base or oxidants. Furthermore, these reactions can proceed by two distinct mechanisms for C?O bond activation. A Pd0/II catalytic cycle is viable when using a Pd0 precatalyst, with turnover‐limiting C?O oxidative addition; however, an alternative pathway that involves alkene carbopalladation and β‐carboxyl elimination is proposed for PdII precatalysts. This work provides a clear path toward engaging myriad oxygen‐based electrophiles in Pd‐catalyzed cross‐coupling. 相似文献
7.
Triazene‐substituted arylboronic esters were prepared readily from the corresponding aryl magnesium derivatives and shown to function as a new class of donor–acceptor‐substituted coupling reagents. The selective functionalization of these aromatic derivatives led to a wide variety of terphenyl derivatives in which the original bifunctional unit (often further substituted with another functional group) formed the central aromatic ring. The functionalized terphenyl derivatives were formed in two efficient cross‐coupling steps from the triazene‐substituted boronic esters: Suzuki cross‐coupling with an aryl halide was followed by BF3?OEt2‐induced palladium‐catalyzed coupling of the diazonium salt generated in situ from the triazene with an arylboronic acid. 相似文献
8.
An alternative approach to develop a Pd catalyst based on dendrimer‐functionalized graphene oxide for C‐C cross‐coupling reactions is reported. Pd@MGO‐D‐NH2 has been synthesized by incipient wet impregnation method. The structure of the catalyst was thoroughly characterized by a set of analytical techniques such as TEM, BET, SEM/EDS, FTIR, and elemental mapping analysis. Then, the catalytic activity of the catalyst was scrutinized for promoting sonogashira C‐C coupling reaction. The results manifested that Pd@MGO‐D‐NH2 was able to catalyze the coupling reaction to obtain high coupling yields in short reaction time. The results of present work are hoped to aid the development of new class of heterogeneous catalysts as the high performance candidate for industrial applications. 相似文献
9.
《Angewandte Chemie (International ed. in English)》2017,56(51):16136-16179
Metal‐catalyzed cross‐coupling reactions belong to the most important transformations in organic synthesis. Copper catalysis has received great attention owing to the low toxicity and low cost of copper. However, traditional Ullmann‐type couplings suffer from limited substrate scopes and harsh reaction conditions. The introduction of several bidentate ligands, such as amino acids, diamines, 1,3‐diketones, and oxalic diamides, over the past two decades has totally changed this situation as these ligands enable the copper‐catalyzed coupling of aryl halides and nucleophiles at both low reaction temperatures and catalyst loadings. The reaction scope has also been greatly expanded, rendering this copper‐based cross‐coupling attractive for both academia and industry. In this Review, we have summarized the latest progress in the development of useful reaction conditions for the coupling of (hetero)aryl halides with different nucleophiles. Additionally, recent advances in copper‐catalyzed coupling reactions with aryl boronates and the copper‐based trifluoromethylation of aromatic electrophiles will be discussed. 相似文献
10.
Graphene‐Oxide‐Catalyzed Direct CH−CH‐Type Cross‐Coupling: The Intrinsic Catalytic Activities of Zigzag Edges
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Dr. Hongru Wu Prof. Dr. Chenliang Su Rika Tandiana Dr. Cuibo Liu Dr. Chuntian Qiu Dr. Yang Bao Dr. Ji'en Wu Dr. Yangsen Xu Prof. Dr. Jiong Lu Prof. Dr. Dianyuan Fan Prof. Dr. Kian Ping Loh 《Angewandte Chemie (International ed. in English)》2018,57(34):10848-10853
The development of graphene oxide (GO)‐based materials for C?C cross‐coupling represents a significant advance in carbocatalysis. Although GO has been used widely in various catalytic reactions, the scope of reactions reported is quite narrow, and the relationships between the type of functional groups present and the specific activity of the GO are not well understood. Herein, we explore CH?CH‐type cross‐coupling of xanthenes with arenes using GO as real carbocatalysts, and not as stoichiometric reactants. Mechanistic studies involving molecular analogues, as well as trapped intermediates, were carried out to probe the active sites, which were traced to quinone‐type functionalities as well as the zigzag edges in GO materials. GO‐catalyzed cross‐dehydrogenative coupling is operationally simple, shows reusability over multiple cycles, can be conducted in air, and exhibits good functional group tolerance. 相似文献
11.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(43):13532-13535
A silica‐supported precatalyst, Pd‐PEPPSI‐IPent‐SiO2, has been prepared and evaluated for its proficiency in the Negishi cross‐coupling of hindered and electronically deactivated coupling partners. The precatalyst Pd‐PEPPSI‐IPent loaded onto packed bed columns shows high catalytic activity for the room‐temperature coupling of deactivated/hindered biaryl partners. Also for the first time, the flowed Csp3–Csp2 coupling of secondary alkylzinc reagents to (hetero)aromatics has been achieved with high selectivity with Pd‐PEPPSI‐IPent‐SiO2. These couplings required residence times as short as 3 minutes to effect completion of these challenging transformations with excellent selectivity for the nonrearranged product. 相似文献
12.
Visible‐Light‐Induced Nickel‐Catalyzed Negishi Cross‐Couplings by Exogenous‐Photosensitizer‐Free Photocatalysis
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Irini Abdiaj Alberto Fontana Dr. M. Victoria Gomez Prof. Antonio de la Hoz Dr. Jesús Alcázar 《Angewandte Chemie (International ed. in English)》2018,57(28):8473-8477
The merging of photoredox and transition‐metal catalysis has become one of the most attractive approaches for carbon–carbon bond formation. Such reactions require the use of two organo‐transition‐metal species, one of which acts as a photosensitizer and the other one as a cross‐coupling catalyst. We report herein an exogenous‐photosensitizer‐free photocatalytic process for the formation of carbon–carbon bonds by direct acceleration of the well‐known nickel‐catalyzed Negishi cross‐coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross‐coupling chemistry that involve the direct visible‐light absorption of organometallic catalytic complexes. 相似文献
13.
A Convenient Protocol for the Synthesis of 2‐(2′‐Hydroxy‐5′‐carboxyphenyl)‐2H‐benzotriazole to Avoid Decarboxylation When Using p‐Hydroxybenzoic Acid as Coupling Component
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Wei Ma Tingting Tuo Jingqiang Hu Yong Liu Shufen Zhang 《Journal of heterocyclic chemistry》2014,51(3):803-807
In the study of the synthesis of 2‐(2′‐hydroxy‐5′‐carboxyphenyl)‐2H‐benzotriazole, we found that decarboxy intermediate‐4‐((2‐nitrophenyl)diazenyl)phenol was obtained when using p‐hydroxybenzoic acid as coupling component. A convenient protocol for the synthesis of 2‐(2′‐hydroxy‐5′‐carboxyphenyl)‐2H‐benzotriazole is reported with methyl‐p‐hydroxybenzoate as coupling component. Different dizao components and different coupling components were also used for further investigation of decarboxylation. 相似文献
14.
Melzig L Metzger A Knochel P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(10):2948-2956
A variety of unsaturated thioethers have been subjected to cross‐coupling reactions with functionalized zinc reagents in the presence of a transition‐metal catalyst. Three different catalytic systems based on Pd(OAc)2 or [Ni(acac)2] and the ligands S‐Phos or DPE‐Phos gave the best results. N‐Heterocyclic thioethers based on a pyridine, pyrimidine, pyrazine, pyridazine, triazine, benzothiazole, benzoxazole, pyrrole, or quinazoline ring, as well as thiomethylacetylenes, serve as electrophiles in this cross‐coupling reaction. Aryl‐, heteroaryl‐, benzylic, and alkylzinc halides with sensitive functionalities, such as ester, nitrile, or ketone groups react at ambient temperature with unsaturated thioethers using a Ni catalyst. The corresponding Pd‐catalyzed reactions require slightly higher temperatures. Large‐scale cross‐coupling experiments (10–20 mmol) with N‐heterocycles are also reported. 相似文献
15.
3‐Alkyl‐2,5‐bis[p‐(hexa‐2,4‐dienoyloxy)phenyl]‐thiophene derivatives were synthesized by using Kumada coupling and Suzuki coupling reactions as key steps. The thermotropic liquid crystalline behavior of these compounds was investigated by optical polarized microscopy, monotropic nematic mesophases were observed in such compounds. 相似文献
16.
Transition‐Metal‐Free Oxidative Cross‐Coupling of Tetraarylborates to Biaryls Using Organic Oxidants
Carolin Gerleve Armido Studer 《Angewandte Chemie (International ed. in English)》2020,59(36):15468-15473
Readily prepared tetraarylborates undergo selective (cross)‐coupling through oxidation with Bobbitt's salt to give symmetric and unsymmetric biaryls. The organic oxoammonium salt can be used either as a stoichiometric oxidant or as a catalyst in combination with in situ generated NO2 and molecular oxygen as the terminal oxidant. For selected cases, oxidative coupling is also possible with NO2/O2 without any additional nitroxide‐based cocatalyst. Transition‐metal‐free catalytic oxidative ligand cross‐coupling of tetraarylborates is unprecedented and the introduced method provides access to various biaryl and heterobiaryl systems. 相似文献
17.
An efficient electrochemical access to the non‐symmetric biphenols using tri(p‐bromophenyl)amine (TBPA) as a redox mediator has been developed. The electrochemical protocol features highly selective cross‐coupling products in up to 83% yield, instead of forming homo‐coupling ones. 相似文献
18.
Excitation energy transfer (EET) is a process where the electronically excitation is transferred from a donor to an acceptor. EET is widely seen in both natural and in artificial systems, such as light‐harvesting in photosynthesis, the fluorescence resonance energy transfer technique, and the design of light‐emitting molecular devices. In this work, we outline the theories describing both singlet and triplet EET (SEET and TEET) rates, with a focus on the physical nature and computational methods for the electronic coupling factor, an important parameter in predicting EET rates. The SEET coupling is dominated by the Coulomb coupling, and the remaining short‐range coupling is very similar to the TEET coupling. The magnitude of the Coulomb coupling in SEET can vary much, but the contribution of short‐range coupling has been found to be similar across different excited states in naphthalene. The exchange coupling has been believed to be the major physical contribution to the short‐range coupling, but it has been pointed out that other contribution, such as the orbital overlap effect is similar or even larger in strength. The computational aspects and the subsequent physical implication for both SEET and TEET coupling values are summarized in this work. © 2013 The Authors. International Journal of Quantum Chemistry Published by Wiley Periodicals, Inc. 相似文献
19.
Significant Enhancement in the Efficiency and Selectivity of Iron‐Catalyzed Oxidative Cross‐Coupling of Phenols by Fluoroalcohols
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Eden Gaster Yulia Vainer Almog Regev Dr. Sachin Narute Dr. Kavitha Sudheendran Aviya Werbeloff Hadas Shalit Dr. Doron Pappo 《Angewandte Chemie (International ed. in English)》2015,54(14):4198-4202
Significant enhancement of both the rate and the chemoselectivity of iron‐catalyzed oxidative coupling of phenols can be achieved in fluorinated solvents, such as 1,1,1,3,3,3‐hexafluoropropan‐2‐ol (HFIP), 2,2,2‐trifluoroethanol (TFE), and 1‐phenyl‐2,2,2‐trifluoroethanol. The generality of this effect was examined for the cross‐coupling of phenols with arenes and polycyclic aromatic hydrocarbons (PAHs) and of phenol with β‐dicarbonyl compounds. The new conditions were utilized in the synthesis of 2′′′‐dehydroxycalodenin B in only four synthetic steps. 相似文献
20.
Palladium‐Catalyzed Oxygenative Cross‐Coupling of Ynamides and Benzyl Bromides by Carbene Migratory Insertion
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Yunpeng Gao Dr. Guojiao Wu Qi Zhou Prof. Dr. Jianbo Wang 《Angewandte Chemie (International ed. in English)》2018,57(10):2716-2720
A palladium‐catalyzed oxygenative cross‐coupling of ynamides and benzyl bromides has been developed. After subsequent hydrogenation, α,α‐disubstituted amide derivatives were obtained in good yields. Migratory insertion of α‐oxo palladium carbene species, generated by intermolecular oxidation, is proposed as the key step in this reaction. The study demonstrates the potential of ynamides to serve as carbene precursors in palladium‐catalyzed C?C bond‐forming cross‐coupling reactions. 相似文献