- Comparison of the Oxidative Coupling Reactions of Benzene with Those of Methane of Rare Earth Oxide Catalysts
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The oxidative coupling of benzene has been compared with that of methane on La2O3, CeO2, Pr6O11, and Sm2O3. At temperatures greater than 1048 K, the gas phase oxidative coupling of benzene appears to be predominant, while the oxidation occurs catalytically at 873 K. The conversion of benzene and of methane at 873 K follows the order of Sm2O3>La2O3>Pr6O11>CeO2, suggesting that the abstraction of hydrogen from the aromatic and the saturated compounds depends primarily on the nature of the catalyst but not the reactant. Ancillary information has also been obtained from the results of XPS analyses of both fresh catalysts and those previously used in one of the reactions.
- Sugiyama, Shigeru,Ookubo, Takashi,Shimodan, Kazuaki,Hayashi, Hiromu,Moffat, John B.
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- Understanding enediyne-protein interactions: Diyl atom transfer results in generation of aminoacyl radicals
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Formula Presented The origin of the protein modulating capacity of enediynes has been probed. A series of synthetic enediyne-derived diyls participated in atom transfer chemistry with a labeled amino acid. Subsequent experiments suggest that diyl radicals may modulate protein architecture via formation of captodatively stabilized radicals.
- Jones, Graham B.,Plourde II, Gary W.,Wright, Justin M.
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Read Online
- Suzuki cross-coupling of hexachlorobenzene promoted by the Buchwald ligands
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The study of cross-coupling between hexachlorobenzene and phenylboronic acid comprised five Buchwald ligands, from which 2-dicyclohexylphosphino-2′-(dimethylamino)biphenyl (DavePHOS) provided the best conversion. When excess of phenylboronic acid was used, a mixture of isomeric tri-, tetra- and pentaphenyl-substituted derivatives in the ～10:70:20 ratio was obtained, along with minor amounts of hydrodechlorination products.
- Burukin, A. S.,Vasil’ev, A. A.,Zhdankina, G. M.,Zlotin, S. G.
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p. 169 - 172
(2022/02/17)
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- Nickel-Catalyzed Ring-Opening Allylation of Cyclopropanols via Homoenolate
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We report herein a nickel-catalyzed ring-opening allylation of cyclopropanols with allylic carbonates that occurs under mild and neutral conditions. The reaction displays linear selectivity for both linear and branched acyclic allylic carbonates and is also applicable to cyclic allylic carbonates, affording a variety of δ,?-unsaturated ketones in moderate to good yields. Mechanistic experiments are in accord with a catalytic cycle involving decarboxylative oxidative addition of allylic carbonate to Ni(0), alkoxide exchange with cyclopropanol, cyclopropoxide-to-homoenolate conversion on Ni(II), and C-C reductive elimination.
- Sekiguchi, Yoshiya,Lee, Yan Ying,Yoshikai, Naohiko
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p. 5993 - 5997
(2021/08/16)
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- Buchwald ligand-assisted Suzuki cross-coupling of polychlorobenzenes
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Screening of four Buchwald ligands for the cross-coupling of isomeric di-, tri- and tetrachlorobenzenes with arylboronic acids revealed that good yields of exhaustive substitution can be best provided by 2-dicyclohexylphosphino-2′-(dimethylamino) biphenyl (DavePHOS).
- Burukin, Alexander S.,Vasil'ev, Andrei A.,Zhdankina, Galina M.,Zlotin, Sergei G.
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p. 400 - 402
(2021/06/07)
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- Experimental and Computational Studies towards Chemoselective C?F over C?Cl Functionalisation: Reversible Oxidative Addition is the Key
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Catalytic cross-coupling is a valuable tool for forming new carbon-carbon and carbon-heteroatom bonds, allowing access to a variety of structurally diverse compounds. However, for this methodology to reach its full potential, precise control over all competing cross-coupling sites in poly-functionalised building blocks is required. Carbon-fluorine bonds are one of the most stable bonds in organic chemistry, with oxidative addition at C?F being much more difficult than at other C-halide bonds. As such, the development of methods to chemoselectively functionalise the C?F position in poly-halogenated arenes would be very challenging if selectivity was to be induced at the oxidative addition step. However, metal-halide complexes exhibit different trends in reactivity to the parent haloarenes, with metal-fluoride complexes known to be very reactive towards transmetalation. In this current work we sought to exploit the divergent reactivity of Ni?Cl and Ni?F intermediates to develop a chemoselective C?F functionalisation protocol, where selectivity is controlled by the transmetalation step. Our experimental studies highlight that such an approach is feasible, with a number of nickel catalysts shown to facilitate Hiyama cross-coupling of 1-fluoronapthalene under base free conditions, while no cross-coupling with 1-chloronapthalene occurred. Computational and experimental studies revealed the importance of reversible C?Cl oxidative addition for the development of selective C?F functionalisation, with ligand effects on the potential for reversibility also presented.
- Jacobs, Emily,Keaveney, Sinead T.
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p. 637 - 645
(2020/12/07)
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- Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
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Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
- Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
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supporting information
p. 10182 - 10185
(2021/10/12)
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- Organocatalyst in Direct C(sp2)-H Arylation of Unactivated Arenes: [1-(2-Hydroxyethyl)-piperazine]-Catalyzed Inter-/Intra-molecular C-H Bond Activation
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This article describes the identification of 1-(2-hydroxyethyl)-piperazine as a new, cost-effective, highly efficient organocatalyst, which promotes both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in the presence of potassium tert-butoxide. While the inter-molecular C-H arylation of unactivated benzenes with aryl halides (Ar-X; X = I, Br, Cl) toward biaryl syntheses underwent smoothly in the presence of only 10 mol percent organocatalyst, the intra-molecular C-H arylation catalytic system composed of 40 mol percent each of the catalyst and the additive (4-dimethylaminopyridine (DMAP)). The novel catalyst was also able to perform both inter- A nd intra-molecular direct arylations simultaneously in a single pot. The mechanistic studies confirmed the involvement of aryl radical anions and proceeded via a single-electron-transfer (SET) mechanism. The large substrate scope, high functional group tolerance, competition experiments, gram-scale synthesis, and kinetic studies further highlight the importance and versatile nature of the methodology as well as the compatibility of the new catalyst. To the best of our knowledge, this is the first report on any organocatalyst that reported detailed investigations of both inter- A nd intra-molecular direct C(sp2)-H arylations of unactivated arenes in a single representation.
- Yadav, Lalit,Tiwari, Mohit K.,Shyamlal, Bharti Rajesh Kumar,Chaudhary, Sandeep
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p. 8121 - 8141
(2020/07/16)
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- Palladium (II)–Salan Complexes as Catalysts for Suzuki–Miyaura C–C Cross-Coupling in Water and Air. Effect of the Various Bridging Units within the Diamine Moieties on the Catalytic Performance
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Water-soluble salan ligands were synthesized by hydrogenation and subsequent sulfonation of salens (N,N’-bis(slicylidene)ethylenediamine and analogues) with various bridging units (linkers) connecting the nitrogen atoms. Pd (II) complexes were obtained in reactions of sulfosalans and [PdCl4]2?. Characterization of the ligands and complexes included extensive X-ray diffraction studies, too. The Pd (II) complexes proved highly active catalysts of the Suzuki–Miyaura reaction of aryl halides and arylboronic acid derivatives at 80 ?C in water and air. A comparative study of the Pd (II)–sulfosalan catalysts showed that the catalytic activity largely increased with increasing linker length and with increasing steric congestion around the N donor atoms of the ligands; the highest specific activity was 40,000 (mol substrate) (mol catalyst × h)?1. The substrate scope was explored with the use of the two most active catalysts, containing 1,4-butylene and 1,2-diphenylethylene linkers, respectively.
- Bunda, Szilvia,Joó, Ferenc,Kathó, ágnes,Udvardy, Antal,Voronova, Krisztina
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supporting information
(2020/09/18)
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- N,S-chelating triazole-thioether ligand for highly efficient palladium-catalyzed Suzuki reaction
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1,2,3-Triazole-thioether compounds could serve as efficient ligands for Pd-catalyzed Suzuki reactions of various aryl iodides, bromides and chlorides. The reactions feature wide substrate scope and mild reaction conditions. Besides, shorter reaction time, lower catalyst loadings and quantitative yields with a turnover-frequency (TOF) value of up to 11,880 h?1 are other advantageous of this attractive protocol. The crystal structure analyses and computational studies revealed that the higher catalytic activity of the corresponding chelated palladium complex ascribed to the lower energy gap and the lower redox potential.
- Yan, Qiong,Zheng, Lei,Li, Miaomiao,Chen, Yunfeng
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p. 101 - 105
(2019/07/19)
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- Palladium-catalysed room-temperature Suzuki–Miyaura coupling in water extract of pomegranate ash, a bio-derived sustainable and renewable medium
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An agro waste-derived, ‘water extract of pomegranate ash’ (WEPA), has been utilized for the first time as a renewable medium for Pd(OAc)2-catalysed Suzuki–Miyaura cross-coupling at room temperature. This method offers a simple and sustainable synthesis of biaryls from aryl halides and arylboronic acids under ligand- and external base-free aerobic and ambient conditions. This method has been found effective for both activated and unactivated aryl halides in the production of biaryls with moderate to nearly quantitative yields. The protocol shows high chemoselectivity over identical/similar reactive sites in aryl halides (i.e. selectivity over identical halogens or different halogens of aryl halides). This method exhibits high regioselectivity, i.e. the selective reactivity of a halogen over other identical halogens at different positions on the aromatic nucleus. Therefore, we disclose here a clean, benign, substantial chemo- and regioselective and highly economic alternative method for the palladium-assisted synthesis of biaryls using an agro waste-derived medium.
- Appa, Rama Moorhy,Prasad, S. Siva,Lakshmidevi, Jangam,Naidu, Bandameeda Ramesh,Narasimhulu, Manchala,Venkateswarlu, Katta
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- Generation of Aryl Radicals from Aryl Halides: Rongalite-Promoted Transition-Metal-Free Arylation
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A new and practical method for the generation of aryl radicals from aryl halides is reported. Rongalite as a novel precursor of super electron donors was used to initiate a series of electron-catalyzed reactions under mild conditions. These transition-metal-free radical chain reactions enable the efficient formation of C-C, C-S, and C-P bonds through homolytic aromatic substitution or SRN1 reactions. Moreover, the synthesis of antipsychotic drug Quetiapine was performed on gram scale through the described method. This protocol demonstrated its potential as a promising arylation method in organic synthesis.
- Yu, Fazhi,Mao, Runyu,Yu, Mingcheng,Gu, Xianfeng,Wang, Yonghui
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p. 9946 - 9956
(2019/09/04)
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- Ring Closing Metathesis Approach for the Synthesis of o-Terphenyl Derivatives
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A linear synthesis of o-terphenyl derivatives has been delineated using ring closing metathesis (RCM) as the key step. In this approach, benzil derivatives upon allyl Grignard addition provides diphenyl-1,2-diallyl dihydroxy derivatives which undergo ring closing metathesis to afford tetrahydro terphenyl derivatives. Aromatization-driven dehydration then leads to a diverse set of electron rich and electron deficient o-terphenyls. Furthermore, oxidative coupling of electron rich o-terphenyls provides the corresponding triphenylene derivatives.
- Karmakar, Shilpi,Mandal, Tirtha,Dash, Jyotirmayee
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p. 5916 - 5924
(2019/08/21)
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- Perylenequinonoid-catalyzed photoredox activation for the direct arylation of (het)arenes with sunlight
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Naturally occurring perylenequinonoid pigments (PQPs) have attracted considerable attention owing to their excellent properties of photosensitization. They have been widely investigated as an aspect of photophysics and photobiology. However, their applications in photocatalysis are yet to be explored. We report here that sunlight along with 1 mol% cercosporin, which is one of the perylenequinonoid pigments, catalyzes the direct C-H bond arylation of (het)arenes by a photoredox process with good regioselectivity and broad functional group compatibility. Furthermore, a gram-scale reaction with great conversions of substrates was achieved even by a cercosporin-containing supernatant without organic solvent extraction and purification after liquid fermentation. Thus we set up a bridge between microbial fermentation and organic photocatalysis for chemical reactions in a sustainable, environmentally friendly manner.
- Zhang, Shiwei,Tang, Zhaocheng,Bao, Wenhao,Li, Jia,Guo, Baodang,Huang, Shuping,Zhang, Yan,Rao, Yijian
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supporting information
p. 4364 - 4369
(2019/05/10)
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- Ni: Vs. Pd in Suzuki-Miyaura sp2-sp2 cross-coupling: A head-to-head study in a comparable precatalyst/ligand system
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The Suzuki-Miyaura reaction is a cornerstone method for sp2-sp2 cross-coupling in industry. There has been a concerted effort to enable the use of Ni catalysis as an alternative to Pd in order to mitigate cost and improve sustainability. Despite significant advances, ligand development for Ni-catalyzed Suzuki-Miyaura cross-coupling remains underdeveloped when compared to Pd and, as a consequence, ligands for Ni-catalyzed processes are typically taken from the Pd arena. In this study we evaluate the effect of using a similar Ni and Pd precatalyst based on a common bidentate ligand (dppf) in a head-to-head format for the most common type of biaryl couplings, establishing the practical implications of direct replacement of Pd with Ni, and identifying the potential origins of these observations in a mechanistic context.
- West, Matthew J.,Watson, Allan J. B.
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supporting information
p. 5055 - 5059
(2019/06/03)
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- Involving Single-Atom Silver(0) in Selective Dehalogenation by AgF under Visible-Light Irradiation
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The dehalogenation-arylation and the hydrodehalogenation of various types of organic halides are selectively realized using AgF and visible light without any organic additives under mild conditions. Single-atom silver(0) (denoted as SAAg) serves as the catalytically active center, and the TOF of SAAg reaches 6000 h-1. This elusive activity of Ag is beyond that expected from its ionic, nano, or bulk forms.
- Wu, Wenli,Cui, Enxin,Zhang, Yun,Zhang, Chen,Zhu, Feng,Tung, Chen-Ho,Wang, Yifeng
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p. 6335 - 6341
(2019/07/04)
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- A Highly Active Catalyst System for Suzuki-Miyaura Coupling of Aryl Chlorides
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A series of new Pd(II) complexes with simple structures were designed and synthesized for Suzuki-Miyaura coupling reactions of aryl chlorides. The new Pd(II) complexes contain bidentate amine ligands, and their structures were characterized by single-crystal X-ray diffraction. They are highly efficient for Suzuki-Miyaura coupling reactions of aryl chlorides with low catalyst loadings (0.01 mol %) in aqueous media at room temperature. Two possible reaction pathways involving a PdII/0/II and a PdII/IV/II catalytic cycle are proposed, and the mechanism was further investigated using density functional theory (DFT) calculations.
- Liu, Guiyan,Han, Fangwai,Liu, Chengxin,Wu, Hongli,Zeng, Yongfei,Zhu, Rongjiao,Yu, Xia,Rao, Shuang,Huang, Genping,Wang, Jianhui
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p. 1459 - 1467
(2019/03/19)
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- Pillarquinone-Based Porous Polymer for a Highly-Efficient Heterogeneous Organometallic Catalysis
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Pillar[5]quinone (PQ[5])-based porous polymer has been prepared by crosslinking and oxidating pillar[5]arene (PA[5]). Quinone was used as an unorthodox ligand to load palladium-catalyst with high loading ratio (up to 12.0 wt %). Catalyst was well dispersed on solid support in the form of Pd2+-specie. Pd-loaded PQ[5]-based heterogeneous catalyst was highly efficient for Suzuki-coupling reactions (22- to 1485-fold higher than Pd/C based on turnover frequency). It was superior compared to other existing heterogeneous catalysts for selective catalytic reaction. This heterogeneous catalyst had good thermo-stability, and could be reused and recycled.
- Lan, Shang,Yang, Xuan,Shi, Kejia,Fan, Rong,Ma, Da
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p. 2864 - 2869
(2019/06/13)
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- Rapid Access to Bi- and Tri-Functionalized Dibenzofurans and their Application in Selective Suzuki–Miyaura Cross Coupling Reactions
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Syntheses of 1,2-, 1,3-, 1,4-, 1,8-, 2,4-, 3,4-, 4,8-, 1,2,4-, 1,2,8- and 1,3,4-functionalized dibenzofurans in few steps with good to excellent yields starting from dibenzofuran-1-ol or -4-ol are presented. These rapidly accessible bi- or tri-functionalized building blocks are of great interest for the synthesis of bioactive substances or functional material development. Furthermore, for intermediates containing both a bromine and a triflate moiety, a selective mono-substitution by means of Suzuki–Miyaura reaction (SMR) is described.
- Wern, Caroline,Ehrenreich, Christian,Joosten, Dominik,Stein, Thorsten vom,Buchholz, Herwig,K?nig, Burkhard
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p. 5644 - 5656
(2018/10/09)
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- Desulfurization of dibenzothiophene and dibenzothiophene sulfone via Suzuki–Miyaura type reaction: Direct access to o-terphenyls and polyphenyl derivatives
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The reactivity of dibenzothiophene (DBT) or dibenzothiophene sulfone (DBTO2) with a variety of phenylboronic acids was mediated by the nickel precursor [Ni(dippe)Cl2] in the presence of a base. The reaction was performed under relatively mild conditions (70–100 °C), in aqueous media. The study of the reactivity revealed the role of water as a hydrogen source and showed a competition between the desulfurization of the corresponding substrates via a hydrodesulfurization (HDS) or by a hydrodesulfurative cross-coupling (HDSCC) reaction. Furthermore, in the absence of water sulfur-free poly-phenylic compounds were obtained in good yields as a result of a Suzuki–Miyaura type reaction, being the main product in most of the cases the corresponding o-terphenyl derivative, these products are valuable building blocks in the synthesis of more complex materials.
- Gutiérrez-Ordaz, Rubén,García, Juventino J.
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supporting information
p. 373 - 381
(2018/08/31)
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- Synthesis of Bi(hetero)aryls via Sequential Oxidation and Decarboxylation of Benzylamines in a Batch/Fully Automated Continuous Flow Process
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Catalytic dehydrogenative cross-coupling of two C–H bonds represents a green strategy in view of the atom- and step-economy. However, the challenge is to discover a new innovative bond strategy, especially for the direct coupling between Csp2–H
- Mahajan, Bhushan,Aand, Dnyaneshwar,Singh, Ajay K.
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supporting information
p. 2831 - 2835
(2018/06/21)
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- Electron-Catalyzed Cross-Coupling of Arylboron Compounds with Aryl Iodides
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Arylboroxines in combination with zinc chloride and potassium tert-butoxide were found to undergo the electron-catalyzed cross-coupling with aryl iodides to give the corresponding biaryls without the aid of transition-metal catalysis.
- Okura, Keisho,Teranishi, Tsuyoshi,Yoshida, Yuto,Shirakawa, Eiji
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supporting information
p. 7186 - 7190
(2018/06/15)
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- Direct Aryl-Aryl Coupling without Pre-Functionalization Enabled by Excessive Oxidation of Two-Electron Ag(I)/Ag(III) Catalyst
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Reported herein is a catalytic platform for formation of unsymmetrical biaryls by the coupling between inert Csp2?CH3 and Csp2?H via a tandem catalytic strategy. The platform utilizes traditional AgNO3 catalyst and excess amount of K2S2O8 oxidant. The excessive oxidant present converts the traditional one-electron Ag(I)/Ag(II) chemistry to two-electron Ag(I)/Ag(III) one, enabling one-pot synthesis of aryl-aryl scaffolds by using unactivated cheap commodity chemicals. (Figure presented.).
- Singh, Ajay K.,Kim, Min-Gyu,Lee, Hyune-Jea,Singh, Rakhi,Cho, Seung Hwan,Kim, Dong-Pyo
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supporting information
p. 2032 - 2042
(2018/04/11)
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- Less hindered ligands give improved catalysts for the nickel catalysed Grignard cross-coupling of aromatic ethers
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The challenging reaction of unactivated ortho-substituted aromatic ethers with Grignard reagents has been found to be most effectively catalysed using nickel complexes of less sterically hindered ligands. Air stable, cheap, commercially available [NiCl2(PnBu3)2] stands out as an improved catalyst for this type of transformation. The improved results with this catalyst even extend to some couplings of a more activated substrate when examined at higher temperatures and at catalyst loadings down to 0.1 mol%. Unusual induction periods in these latter reactions have been related to the by-product magnesium salts acting as co-catalysts.
- Harkness, Gavin J.,Clarke, Matthew L.
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p. 328 - 334
(2018/01/12)
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- Acetylacetonato-based pincer-type nickel(ii) complexes: Synthesis and catalysis in cross-couplings of aryl chlorides with aryl Grignard reagents
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In this work, three different types of acetylacetonato-based pincer-type nickel(ii) complexes (2) were prepared. Complex 2a possessed the tridentate ONN ligand, which was constructed by the condensation reaction of acetylacetone with N,N-diethylethylenediamine. Complex 2b contained the PPh2 donor group in contrast to the NEt2 group in 2a, i.e., an ONP ligand framework. Complex 2c was composed of the NNN ligand, which was prepared by the reaction of 4-((2,4,6-trimethylphenyl)amino)pent-3-en-2-one with N,N-diethylethylenediamine. In addition to X-ray diffraction analysis, these complexes were characterized spectroscopically. Their catalytic activity for a cross-coupling reaction of aryl halides with aryl Grignard reagents was also evaluated. Among these complexes, 2b acted as an effective catalyst for the cross-coupling reaction using aryl chlorides as electrophiles. The electronic properties of these Ni(ii) complexes were investigated by cyclic voltammetry and density functional theory calculations.
- Asano, Erika,Hatayama, Yuki,Kurisu, Nobutaka,Ohtani, Atsufumi,Hashimoto, Toru,Kurihara, Youji,Ueda, Kazuyoshi,Ishihara, Shinji,Nagao, Hirotaka,Yamaguchi, Yoshitaka
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p. 8003 - 8012
(2018/06/29)
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- Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) cobalt hydride for Kumada coupling reactions
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The electron-rich silylene Co(i) chloride 5 was obtained through the reaction of CoCl(PMe3)3 with chlorosilylene. Complex 5 reacted with 1,3-siladiazole HSiMe(NCH2PPh2)2C6H4 to give the silylene Co(iii) hydride 6 through chelate-assisted Si-H activation. To the best of our knowledge, complex 6 is the first example of Co(iii) hydride supported by N-heterocyclic silylene. Complexes 5 and 6 were fully characterized by spectroscopic methods and X-ray diffraction analysis. Complex 6 was used as an efficient precatalyst for Kumada cross-coupling reactions. Compared with the related complex 3 supported by only trimethylphosphine, complex 6 as a catalyst supported by both chlorosilylene and trimethylphosphine exhibits a more efficient performance for the Kumada cross-coupling reactions. A novel catalytic radical mechanism was suggested and experimentally verified. As an intermediate silylene cobalt(ii) chloride 6d was isolated and structurally characterized.
- Qi, Xinghao,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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p. 2581 - 2588
(2018/02/28)
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- Benzyloxycalix[8]arene: A new valuable support for NHC palladium complexes in C-C Suzuki-Miyaura couplings
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Benzyloxycalix[8]arene supported catalysts bearing N-heterocyclic carbene palladium complexes on each subunit were readily synthesized. Intermediates and catalysts were fully characterized, allowing for a fine control of their structure. X-ray diffraction analysis confirmed the formation of a calix[8]arene bearing eight well-defined NHC palladium complexes. The macrocyclic structure of calix[8]arenes allowed for a scalable and chromatography-free catalyst synthesis under homogeneous conditions, while the catalytic reaction proceeded under heterogeneous conditions, just by changing the nature of the solvent. Indeed, when used as a suspension in ethanol, a high TON and TOF were obtained through a large panel of functionalized brominated substrates in C-C Suzuki-Miyaura couplings, with low metal contamination after simple filtration.
- Abdellah, Ibrahim,Kasongo, Pauline,Labattut, Axel,Guillot, Régis,Schulz, Emmanuelle,Martini, Cyril,Huc, Vincent
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supporting information
p. 13843 - 13848
(2018/10/20)
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- Arylation of hydrocarbons enabled by organosilicon reagents and weakly coordinating anions
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Over the past 80 years, phenyl cation intermediates have been implicated in a variety of C-H arylation reactions. Although these examples have inspired several theoretical and mechanistic studies, aryl cation equivalents have received limited attention in organic methodology. Their high-energy, promiscuous reactivity profiles have hampered applications in selective intermolecular processes. We report a reaction design that overcomes these challenges. Specifically, we found that b-silicon-stabilized aryl cation equivalents, generated via silylium-mediated fluoride activation, undergo insertion into sp3 and sp2 C-H bonds. This reaction manifold provides a framework for the catalytic arylation of hydrocarbons, including simple alkanes such as methane. This process uses low loadings of Earth-abundant initiators (1 to 5 mole percent) and occurs under mild conditions (30° to 100°C).
- Shao, Brian,Bagdasarian, Alex L.,Popov, Stasik,Nelson, Hosea M.
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- Synthesis of zwitterionic palladium complexes and their application as catalysts in cross-coupling reactions of aryl, heteroaryl and benzyl bromides with organoboron reagents in neat water
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N-(3-Chloro-2-quinoxalinyl)-N′-arylimidazolium salts (aryl = 2,6-diisopropylphenyl [HL1Cl]Cl, aryl = mesityl [HL2Cl]Cl) have been synthesized by treating 2,3-dichloroquinoxaline with the corresponding N′-arylimidazole in neat water. Facile reactions of these imidazolium salts with Pd(PPh3)4 and Pd2(dba)3/PPh3 (dba = dibenzyledene acetone) at 50 °C have afforded zwitterionic palladium(ii) complexes [Pd(HL1)(PPh3)Cl2] (I) and [Pd(HL2)(PPh3)Cl2] (II) in excellent yields. I and II have been tested for their ability to catalyze Suzuki-Miyaura cross coupling (SMC) reactions in neat water/K2CO3 and are found to be highly active for carrying out these reactions between aryl bromides and organoboron reagents. Furthermore, the scope of the catalyst I was also examined by employing (hetero)aryl bromides, hydrophilic aryl bromides, benzyl bromides and various organoboron reagents. More than 80 aryl/benzyl bromide-arylboronic acid combinations were screened in neat water/K2CO3 and it was found that I was a versatile catalyst, which produced biaryls/diarylmethanes in excellent yields. A TON of 82 000 was achieved by using I. Studies on the mechanism have also been carried out to investigate the involvement of carbene complexes in the catalytic path. Poison tests and a two-phase test were also conducted and the results are reported.
- Ramakrishna,Dastagiri Reddy
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p. 8598 - 8610
(2017/07/12)
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- ONE STEP DIRECT ARYLATION OF COMMODITY CHEMICALS TO SPECIALTY CHEMICALS BY TANDEM CATALYTIC PLATFORM
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The present invention relates to a continuous direct arylation process based on a tandem catalyst for synthesizing specialty chemicals. A method for synthesizing an aryl-aryl structure from a substrate selected from the group consisting of benzyl alcohol, benzyl amine and toluene which are low value added compounds is developed using a silver ion-containing tandem catalyst. The method is applied for synthesizing hexaphenyl arylene and can be applied for synthesizing high value added compounds (not only natural substances and chemical compounds but pharmaceutical and agricultural pesticide relative fields) directly from primary raw materials through the reaction.COPYRIGHT KIPO 2017
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Paragraph 0057; 0058; 0066-0103; 0106
(2018/02/28)
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- Pd-catalyzed Suzuki–Miyaura cross-coupling of [Ph2SR][OTf] with arylboronic acids
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The Pd-catalyzed Suzuki–Miyaura cross-coupling of alkyl- and fluoroalkyl(diphenyl)sulfonium triflates with arylboronic acids was compared. The fluorine substitution on the alkyl groups of [Ph2SR][OTf] had a big influence on the reaction. Perfluoroalkyl(diphenyl)sulfonium triflates (2b–d) were unsuccessful participants in the Pd-catalyzed phenylation of arylboronic acid under the standard conditions because of the strong electronegativity of the long-chain perfluoroalkyl groups, which underwent S[sbnd]Rfnbond cleavage instead. Polyfluoroalkyl(diphenyl)sulfonium triflates (2f–h) reacted with arylboronic acid to afford the phenylation product in very low yields due to the tendency of deprotonation and β-F elimination of the sulfonium salts. Eventually, (2,2,2-trifluoroethyl)diphenylsulfonium triflate (2e), methyl- or ethyl(diphenyl)sulfonium triflate (2i or 2j), and triphenylsulfonium triflate (2m) were found to be more effective reagents than other tested phenylsulfounium salts for Pd-catalyzed phenylation, which provided much higher yields of the desired products under mild conditions.
- Wang, Xiao-Yan,Song, Hai-Xia,Wang, Shi-Meng,Yang, Jing,Qin, Hua-Li,Jiang, Xin,Zhang, Cheng-Pan
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p. 7606 - 7612
(2016/11/11)
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- Pd-catalyzed divergent trifluoroethylation and arylation of arylboronic acids by aryl(2,2,2-trifluoroethyl)iodonium triflates
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Highly electrophilic aryl(2,2,2-trifluoroethyl)iodonium triflates have been used for the first time as trifluoroethyl and aryl transfer reagents in Pd-catalyzed functionalization of arylboronic acids. Electron-rich arylboronic acids reacted with aryl(2,2,
- Yang, Jing,Han, Qiu-Yan,Zhao, Cheng-Long,Dong, Tao,Hou, Zhi-Yuan,Qin, Hua-Li,Zhang, Cheng-Pan
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supporting information
p. 7654 - 7658
(2016/08/24)
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- Nickel-Catalyzed Cross-Coupling of Organolithium Reagents with (Hetero)Aryl Electrophiles
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Nickel-catalyzed selective cross-coupling of aromatic electrophiles (bromides, chlorides, fluorides and methyl ethers) with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene (NHC) complex allows the reaction with a variety of (hetero)aryllithium compounds, including those prepared via metal-halogen exchange or direct metallation, whereas a commercially available electron-rich nickel-bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product. These reactions proceed rapidly (1 h) under mild conditions (room temperature) while avoiding the undesired formation of reduced or homocoupled products. Nickel-catalyzed cross-coupling of aromatic electrophiles with organolithium reagents is presented. The use of a commercially available nickel N-heterocyclic carbene complex allows reaction with a variety of (hetero)aryllithium compounds, whereas a commercially available electron-rich nickel bisphosphine complex smoothly converts alkyllithium species into the corresponding coupled product.
- Heijnen, Dorus,Gualtierotti, Jean-Baptiste,Hornillos, Valentín,Feringa, Ben L.
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supporting information
p. 3991 - 3995
(2016/03/16)
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- Synthesis and Reactivity of N-Heterocyclic PSiP Pincer Iron and Cobalt Complexes and Catalytic Application of Cobalt Hydride in Kumada Coupling Reactions
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The new N-heterocyclic σ-silyl pincer ligand HSiMe(NCH2PPh2)2C6H4 (1) was designed. A series of tridentate silyl pincer Fe and Co complexes were prepared. Most of them were formed by chelate-assisted Si-H activation. The typical iron hydrido complex FeH(PMe3)2(SiMe(NCH2PPh2)2C6H4) (2) was obtained by Si-H activation of compound 1 with Fe(PMe3)4. The combination of compound 1 with CoMe(PMe3)4 afforded the Co(I) complex Co(PMe3)2(SiMe(NCH2PPh2)2C6H4) (3). The Co(III) complex CoHCl(PMe3)(SiMe(NCH2PPh2)2C6H4) (5) was generated by the reaction of complex 1 with CoCl(PMe3)3 or the combination of complex 3 with HCl. However, when complex 3 was treated with MeI, the Co(II) complex CoI(PMe3)(SiMe(NCH2PPh2)2C6H4) (4), rather than the Co(III) complex, was isolated. The catalytic performance of complex 5 for Kumada coupling reactions was explored. With a catalyst loading of 5 mol %, complex 5 displayed efficient catalytic activity for Kumada cross-coupling reactions of aryl chlorides and aryl bromides with Grignard reagents. This catalytic reaction mechanism is proposed and partially experimentally verified.
- Xiong, Zichang,Li, Xiaoyan,Zhang, Shumiao,Shi, Yaomin,Sun, Hongjian
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p. 357 - 363
(2016/02/19)
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- Palladium-catalyzed synthesis of diarylbenzenes from coupling reactions between equal amount of diiodoarenes and arylboronic acids
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We reported a highly effective Pd-catalytic system for the synthesis of diarylbenzenes through Suzuki-type reaction between equal amount of diiodoarenes and arylboronic acids. This preferential oxidative addition resulted in such high selectivity.
- Mao, Jincheng,Li, Ran,He, Yue,Yang, Xiaojiang,Wang, Dingli,Zhang, Yang
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p. 663 - 669
(2016/07/26)
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- Synthesis of symmetrical terphenyl derivatives by PdCl 2-catalyzed Suzuki-Miyaura reaction of dibromobenzene using 3-(diphenylphosphino)propanoic acid as a ligand
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A simple and efficient catalytic system for PdCl2 catalyzing the Suzuki-Miyaura reaction of dibromobenzene and arylboronic acid has been developed by using 3-(diphenylphosphino)propanoic acid as a ligand in dimethylsulfoxide at 100 °C. Using this method, a series of symmetrical terphenyl derivatives were obtained with remarkably good yields, up to 93%.
- Gu, Ningning,Liu, Yashuai,Liu, Ping,Ma, Xiaowei,Liu, Yan
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supporting information
p. 154 - 159
(2016/02/23)
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- Aerobic Oxidative Intramolecular Aromatic Coupling via Heterogeneous Metal Catalysts
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An aerobic, heterogeneously catalyzed oxidative intramolecular coupling reaction of aromatic compounds is reported here. Using commercially available, recyclable heterogeneous metal catalysts, the coupling reactions of o-terphenyls and 1,ω-biarylalkanes proceeded quickly under mild conditions, i.e., at room temperature under oxygen as a co-oxidant almost all within 1 h, to provide the corresponding coupled products like triphenylenes and phenanthrenes in good to excellent yields. This reaction is an easily handled, practical, and atom-economical coupling method, which is of great importance in modern organic syntheses. (Figure presented.).
- Fujimoto, Shigenobu,Matsumoto, Kenji,Shindo, Mitsuru
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supporting information
p. 3057 - 3061
(2016/10/09)
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- Air-Stable Dinuclear Iodine-Bridged Pd(I) Complex - Catalyst, Precursor, or Parasite? the Additive Decides. Systematic Nucleophile-Activity Study and Application as Precatalyst in Cross-Coupling
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Dinuclear Pd(I) complexes were recently shown to potentially adopt various possible roles in catalysis, being capable of functioning as catalyst via dinuclear catalysis cycles, precatalyst for Pd(0), or inhibitor. This report examines the factors that control the mechanistic role in catalysis. Our data suggest that the transformation to Pd(0) occurs via nucleophile-induced fragmentation of Pd(I)-Pd(I). A systematic study examining the nucleophilicity of additive versus activity was undertaken that revealed the minimum nucleophilicity necessary to activate two structurally very similar Pd(I) dimers, [Pd(μ-X)(PtBu3)]2 (X = I or Br). While the more labile bromine-bridged Pd(I) dimer is converted to Pd(0) with nucleophiles N ≥ 10.5, the iodine-bridged analogue requires N ≥ 16.1 (N according to Mayrs scale). Too strong nucleophiles generate a high concentration of unstable monoligated Pd(0) rapidly, leading to Pd loss (i.e., Pd black). On the other hand, careful tuning of nucleophilicity allows for a controlled release of well-defined Pd(0) species. These insights have led to the first application of the air-stable and previously thought unreactive iodine-bridged dimer [Pd(μ-I)(PtBu3)]2 as a precatalyst for monoligated Pd(0) in cross-coupling reactions. The reactions were performed without exclusion of oxygen-all reagents were handled in air without special precautions. Highly efficient Kumada couplings of aryl iodides and bromides were achieved in 5 min at room temperature.
- Aufiero, Marialuisa,Scattolin, Thomas,Proutière, Fabien,Schoenebeck, Franziska
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supporting information
p. 5191 - 5195
(2015/11/09)
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- Palladium-catalyzed denitrogenative Hiyama cross-coupling with arylhydrazines under air
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A Pd-catalyzed denitrogenative Hiyama coupling of arylhydrazines and aryl silanes is described under mild conditions. The newly developed catalytic system does not require the use of expensive silver- or copper-based stoichiometric oxidants to obtain diaryl derivatives with high selectivity and reactivity. The reported coupling reactions are very practical as they do not require the protection of inert gas or oxygen and are tolerant to many functional groups.
- Zhang, Hui,Wang, Chunjie,Li, Zhiwei,Wang, Ziyun
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supporting information
p. 5371 - 5376
(2015/09/15)
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- Synthesis of Fluoren-9-ones and Ladder-Type Oligo-p-phenylene Cores via Pd-Catalyzed Carbonylative Multiple C-C Bond Formation
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A new route to various substituted fluoren-9-ones has been developed via an efficient Pd-catalyzed carbonylative multiple C-C bond formation. Under a CO atmosphere, using commercially available aryl halides and arylboronic acids as substrates, this three-component reaction proceeded smoothly in moderate to excellent yields with good functional-group compatibility. The mechanistic investigations suggested a sequential process for the reaction that forms o-bromobiaryls in the first stage followed by a cyclocarbonylation reaction. This chemistry has been successfully extended to construct ladder-type oligo-p-phenylene cores. (Chemical Equation Presented).
- Song, Juan,Wei, Fuliang,Sun, Wei,Li, Ke,Tian, Yanan,Liu, Chao,Li, Yali,Xie, Linghai
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supporting information
p. 2106 - 2109
(2015/05/13)
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- Selective and general exhaustive cross-coupling of di-chloroarenes with a deficit of nucleophiles mediated by a Pd-NHC complex
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We report the first example of a general, exhaustive Pd-mediated cross-coupling of polychloroarenes in the presence of a deficit of nucleophiles, mediated by the highly active PEPPSI-IPent catalyst. Our results indicate that this catalyst system may be applicable to the pseudo-living polymerisation of chloroarene monomers.
- Groombridge, Benjamin J.,Goldup, Stephen M.,Larrosa, Igor
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supporting information
p. 3832 - 3834
(2015/03/30)
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- Ligand-controlled chemoselectivity in potassium tert-amylate-promoted direct C-H arylation of unactivated benzene with aryl halides
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Direct C-H arylation of unactivated benzene with aryl halides under various simple ligands (EDA, DMEDA, ethylene glycol, etc.) in the presence of potassium tert-amylate (t-AmOK) base at mild temperature (80 °C) have been developed. This transition-metal-free radical cross-coupling offers an efficient way to synthesize various biaryls in good yields through base-promoted homolytic aromatic substitution. And mechanistic investigations have provided insight into the chemoselectivity of couplings between haloiodobenzenes and benzene and showed that phenanthroline and its derivatives not only initiate these radical reactions like most of other ligands (EDA, DMEDA, ethylene glycol, etc.), but also participate in the electron transfer process of biaryl radical anion intermediates.
- Liu, Wei,Xu, Lige
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p. 4974 - 4981
(2015/06/25)
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- Magnetic nanoparticle-supported Pd(II)-cryptand 22 complex: An efficient and reusable heterogeneous precatalyst in the Suzuki-Miyaura coupling and the formation of aryl-sulfur bonds in honor and memory of late Prof. Mathias Mertes
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In the present work, silica-coated magnetic nanoparticles [Fe3O4@SiO2@C22-Pd(II)] were prepared and characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometer, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, elemental analysis, inductively coupled plasma, thermogravimetric and differential thermal analysis. This heterogeneous catalyst is utilized as an effective catalyst for the Suzuki-Miyaura coupling of arylboronic acids and aryl halides, and the cross-coupling reaction of aryl halides and thiols. The catalyst was easily separated by magnetic decantation and the recovered catalyst was reused for five cycles without any significant loss of the catalytic activity.
- Movassagh, Barahman,Takallou, Ahmad,Mobaraki, Akbar
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- PEPPSI-effect on suzuki-miyaura reactions using 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene-palladium complexes: A comparison between trans-ligands
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The PEPPSI (Pyridine Enhanced Precatalyst Preparation, Stabilization and Initiation) complexes 12-15 with the structure [PdCl2{(CN)2IMes}(3-R-py)] (12: R = H; 13: R = Cl; 14: R = Br; 15: R = CN) bearing the maleonitrile-based N-heterocyclic carbene (NHC) (CN)2IMes ({(CN)2IMes}: 4,5-dicyano-1,3-dimesitylimidazol-2-ylidene) were prepared. Solid state structures of 14 and 15 were obtained. Complexes 14 and 15 adopt a slightly distorted square-planar coordination geometry in the solid state with the substituted pyridine ligand trans to the NHC. Catalytic activities of precatalysts 12-15 were studied and subsequently compared to complexes [PdCl2{(CN)2IMes}(PPh3)] (4) and [PdCl(dmba){(CN)2IMes}] (5) recently reported by our group in the Suzuki-Miyaura reaction of various aryl halides and phenylboronic acid. Reactions using previously reported [PdCl2(IMes)(py)] (IMes: 1,3-dimesitylimidazol-2-ylidene) (1) were also carried out and their results contrasted to those involving 12-15, 4 and 5. Differences in initiation rates and the catalytically active species related to the seven complexes in regards to the "throw away ligand" were investigated. Poisoning experiments with mercury show that palladium nanoparticles are responsible for the catalytic activity.
- Baier, Heiko,Kelling, Alexandra,Holdt, Hans-Jürgen
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p. 1950 - 1957
(2015/04/22)
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- Triphyrin catalyzed direct C-H arylation of benzene with aryl halides
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Transition-metal free direct C-H arylation of benzene with aryl halides was achieved by meso-aryl-substituted [14]triphyrins(2.1.1) catalysts in an air atmosphere. Various aryl halides underwent successful direct C-H arylation of benzene to give moderate to high yields of biaryls. A radical mechanism is proposed for this triphyrin catalyzed C-H arylation reaction.
- Xue, Zhao-Li,Qian, Ying Ying,Chan, Kin Shing
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supporting information
p. 6180 - 6183
(2015/02/19)
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- Reduced graphene oxide supported Ni nanoparticles: A high performance reusable heterogeneous catalyst for Kumada-Corriu cross-coupling reactions
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Reduced graphene oxide (RGO) has emerged as an excellent 2D catalyst support. A high concentration of air stable Ni(0) nanoparticles (～40 wt%) of average size 11 nm can be loaded on reduced graphene oxide. In this article Kumada-Corriu cross-coupling reactions have been studied extensively using RGO supported 40 wt% Ni nanoparticles (Ni/RGO-40) as a heterogeneous catalyst. The reaction conditions were optimized by performing the cross-coupling between 4-iodoanisole and phenylmagnesium chloride in the presence of a catalytic amount of Ni/RGO-40. A detailed study of the catalysis was performed by varying the haloarenes and Grignard reagents under the optimized conditions with yields of 91-72%. The products were characterized by 1H and 13C NMR spectroscopy. The catalyst was found to be significantly reusable. Finally the recovered Ni/RGO-40 was characterized by X-ray diffraction (XRD) and Raman spectroscopy and found to be unaffected. Considering the catalytic performance, reusability and economic reasons, Ni/RGO-40 can be of technological importance.
- Bhowmik, Koushik,Sengupta, Debasish,Basu, Basudeb,De, Goutam
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p. 35442 - 35448
(2014/11/07)
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- PF6-promoted ligandless suzuki-miyaura coupling reaction of potassium aryltrifluoroborates in water
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The Suzuki-Miyaura coupling reactions of potassium aryltrifluoroborates with aryl bromides in water are promoted by the addition of [bmim]PF6 using Pd(OAc)2 as a catalyst and Na2CO3 as a base under air. The quantity of [bmim]PF6 used is crucial to the efficiency of the catalytic system. A wide range of biaryls and polyaryls can be easily prepared in good to excellent yields.
- Liu, Leifang,Dong, Yan,Pang, Bo,Ma, Jiahai
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p. 7193 - 7198
(2014/08/18)
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- Pincer nickel(ii) complexes of N-heterocyclic carbene (NHC): Synthesis and catalysis of the Kumada reaction of unactivated C-Cl bonds
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Three novel [CNN]-pincer nickel(ii) complexes with NHC-amine arms were synthesized in three steps. Complex 5b was proven to be an efficient catalyst for the Kumada coupling of aryl chlorides or aryl dichlorides under mild conditions.
- Sun, Yunqiang,Li, Xiaoyan,Sun, Hongjian
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supporting information
p. 9410 - 9413
(2014/06/23)
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- Synthesis, characterization and catalytic activity of new aminomethyldiphosphine-Pd(II) complexes for Suzuki cross-coupling reaction
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A new range of CF3-substituted aminomethyldiphosphine (P - C - N) ligands ((C6H5)2PCH2) 2NR (R = - C6H4(2-CF3) (1), - C 6H4(3-CF3) (1b) has been synthesized from 2-(trifluoromethyl)aniline and 3-(trifluoromethyl)aniline with diphenylphosphine. The aminomethyldiphosphine ligands were reacted with Pd(cod)Cl2 to give corresponding metal complexes, PdLCl2 (2a, 2b). The aminomethyldiphosphine-palladium compounds were characterized by utilizing several methods including NMR (1H, 13C, 31P) and elemental analysis. These compounds were used as catalysts in Suzuki cross-coupling reaction of aryl chlorides and bromides. The effect of base was also investigated in this current project. CF3-substituted aminomethyldiphosphine-palladium complexes were found to be efficient catalysts in Suzuki cross-coupling reaction of activated and deactivated aryl boronic acids.
- Keles, Mustafa,Yilmaz, Mustafa Kemal
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- Role of the base and control of selectivity in the suzuki-miyaura cross-coupling reaction
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The outcome of the Suzuki-Miyaura cross-coupling for the direct competition reaction between two boronic acids was evaluated under routine synthesis conditions. The reaction selectivity was found to depend on the amount of the base used, with fewer bases
- Lima, Carlos F. R. A. C.,Rodrigues, Ana S. M. C.,Silva, Vera L. M.,Silva, Artur M. S.,Santos, Luis M. N. B. F.
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p. 1291 - 1302
(2014/05/20)
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- Single-electron-transfer-induced coupling of arylzinc reagents with aryl and alkenyl halides
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Arylzinc reagents, prepared from aryl halides/zinc powder or aryl Grignard reagents/zinc chloride, were found to undergo coupling with aryl and alkenyl halides without the aid of transition-metal catalysis to give biaryls and styrene derivatives, respectively. In this context, we have already reported the corresponding reaction using aryl Grignard reagents instead of arylzinc reagents. Compared with the Grignard cross-coupling, the present reaction features high functional-group tolerance, whereby electrophilic groups such as alkoxycarbonyl and cyano groups are compatible as substituents on both the arylzinc reagents and the aryl halides. Aryl halides receive a single electron and thereby become activated as the corresponding anion radicals, which react with arylzinc reagents, thus leading to the cross-coupling products. Arylzinc reagents were found to undergo coupling with aryl and alkenyl halides to give biaryl and styrene derivatives, respectively. The cross-coupling, which features high functional-group tolerance, proceeds through a single-electron-transfer mechanism and thus does not require the aid of transition-metal catalysis.
- Shirakawa, Eiji,Tamakuni, Fumiko,Kusano, Eugene,Uchiyama, Nanase,Konagaya, Wataru,Watabe, Ryo,Hayashi, Tamio
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p. 521 - 525
(2014/01/23)
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- An easily prepared palladium-hydrogel nanocomposite catalyst for C-C coupling reactions
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Supported metallic nanoparticles are important composite materials owing to their enormous potential for applications in various fields. In this work, palladium nanoparticles were prepared in situ in a calcium-cholate (Ca-Ch) hydrogel by reduction with sodium cyanoborohydride. The hydrogel matrix appeared to assist the controlled growth as well as stabilization of palladium nanoparticles. The palladium nanoparticle/Ca-Ch hydrogel hybrid was characterized by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Furthermore, the PdNP/Ca-Ch hybrid xerogel was shown to act as an active catalyst for the Suzuki reaction under aqueous aerobic conditions. The PdNP/Ca-Ch xerogel retains its catalytic activities on storage for several months.
- Maity, Mitasree,Maitra, Uday
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supporting information
p. 18952 - 18958
(2014/12/10)
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