- A water-soluble pyridyl-triazole ligand for aqueous phase palladium catalyzed Suzuki-Miyaura coupling
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An environmentally friendly water-soluble ligand has been prepared by "clicking" 2-(azidomethyl)pyridine with but-3-ynyl sodium sulphate. In situ combination of the new ligand with [Pd(η3-C 3H5)Cl]2 (Pd:ligand =
- Amadio, Emanuele,Scrivanti, Alberto,Beghetto, Valentina,Bertoldini, Matteo,Alam, Md. Mahbubul,Matteoli, Ugo
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- Palladium Separation by Pd-Catalyzed Gel Formation via Alkyne Coupling
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Selective entrapment of precious metals from industrial wastes containing various metals is a most challenging branch of environmental science. Developed methods like solvent or solid-phase extraction, ion exchange, co-precipitation, membrane filtration, and adsorption rely on chelation, electrostatic attraction, or ion exchange, and these methods present limited selectivity and require post-treatment for further application. Herein, an original concept is reported involving the utilization of the superior catalytic properties of Pd selectively for efficient entrapment of Pd from other metals. Specifically, side chains of poly(vinyl alcohol) (PVA) functionalized with alkynyl groups are catalytically dimerized using Pd(II), which forms gels. The Pd(II) ions are coordinatively encapsulated into the gel networks, while the other metal ions are excluded from the networks, thus allowing the separation and immobilization of Pd. The entrapped Pd(II) is also reduced to Pd(0) nanoparticles (PdNPs) forming PdNPs@alkyne-PVA aerogels that exhibit a high catalytic activity for the Suzuki-Miyaura cross-coupling reaction. PdNPs@alkyne-PVA aerogels are further carbonized to PdNPs@C networks for the efficient electrochemical hydrogen evolution reaction. This method provides an effective way not only to selectively separate Pd but also to utilize the entrapped Pd resources for multiple catalyses without further post-treatment of the entrapped Pd source.
- Yang, Xiaojiao,Chen, Jinfan,Hu, Liangsheng,Wei, Jianyu,Shuai, Maobin,Huang, Deshun,Yue, Guozong,Astruc, Didier,Zhao, Pengxiang
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- Palladacycle from cyclometalation of the unsubstituted cyclopentadienyl ring in ferrocene: Synthesis, characterization, theoretical studies, and application to suzuki-miyaura reaction
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The ferrocenylimines of general formula [(η5-C5H5)Fe(η5-C5H4)-CH2N=CH-C(R)=CH-C6H5] with R = H (2a) and CH3 (2b) were conveniently prepared from ferrocenylmethylamine. Reaction of 2a,b with lithium tetrachloropalladate in methanol in the presence of anhydrous sodium acetate resulted in the formation of the di-μ-chloro-bridged heteroannular cyclopalladated complexes 3a,b via the unsubstituted ferrocenyl C-H bond activation of the related ligands. Treatment of 3a,b with triphenylphosphine gave Pd{[(η5-C5H4)Fe(η5-C5H4)CH2N=CH-CH=CH-C6H5]}ClPPh3 (4a) and Pd{[(η5-C5H4)Fe(η5-C5H4)-CH2N=CH-C(CH3)=CH-C6H5]}ClPPh3 (4b), respectively. The crystal structures of 4a,b confirmed the formation of a carbon-palladium bond by using a carbon atom in the unsubstituted cyclopentadienyl ring. Additionally, theoretical studies using density functional theory calculations were carried out in order to account for the regioselectivity of cyclometalation. As for the catalysts, using 0.1% of palladacycles 4a,b in the presence of K3PO4·7H2O as base exhibited excellent yields in the Suzuki-Miyaura coupling reaction of aryl bromides with phenylboronic acid.
- Qian, Hengyu,Yin, Zhigang,Zhang, Tongyan,Yan, Shihai,Wang, Quanling,Zhang, Chunxia
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- Heterogeneous or homogeneous? A case study involving palladium-containing perovskites in the Suzuki reaction
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The utility of a series of palladium-containing perovskite catalysts in the Suzuki reaction is described; turnover numbers of up to 400,000 are reported. A detailed investigation into the mode of action of these catalysts encompassing kinetic studies, catalyst poisoning, microscopy and three-phase tests demonstrate that these heterogeneous materials are pre-catalysts that operate by a solution-phase mechanism.
- Andrews, Stephen P.,Stepan, Antonia F.,Tanaka, Hirohisa,Ley, Steven V.,Smith, Martin D.
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- Cross-coupling reactions catalyzed by P, O chelate palladium complexes at room temperature
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A new catalytic system based on P, O chelate palladium complexes for cross-coupling reactions is described. These catalysts have all shown high activity and selectivity under mild reaction condition.
- Guo, Mengping,Jian, Fangfang,He, Ren
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- A mesoporous "shell-in-shell" structured nanocatalyst with large surface area, enhanced synergy, and improved catalytic performance for Suzuki-Miyaura coupling reaction
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A novel mesoporous "shell-in-shell" structured nanocatalyst (@Pd/meso-TiO2/Pd@meso-SiO2) with large surface area, enhanced synergy, and improved catalytic performance is created for catalyzing Suzuki-Miyaura coupling and 4-nitrophenol reduction reactions. This journal is
- Liu, Baocang,Niu, Yuefang,Li, Yan,Yang, Fan,Guo, Jiamin,Wang, Qin,Jing, Peng,Zhang, Jun,Yun, Guohong
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- Palladium nanoparticles immobilized over Strawberry fruit extract coated Fe3O4 NPs: A magnetic reusable nanocatalyst for Suzuki-Miyaura coupling reactions
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This paper develops a green method for in situ decorated of palladium nanoparticles over Fe3O4 nanoparticles, by utilizing Strawberry fruit extract and ultrasound irradiations, with no use of any toxic reducing agent. The structure's characterization is represented via diverse analytical methods such as FT-IR, FE-SEM, TEM, WDX, ICP, EDS and XXPS. Catalytic efficiency of magnetic Fe3O4@Strawberry/Pd nanocatalyst is investigated in production of different biphenyls with good turnover frequencies (TOF) and turnover numbers (TON) through Suzuki coupling reactions. Furthermore, the catalyst could be recovered and reused 7 runs without considerable palladium leaching or alteration in its performance.
- Hemmati, Saba,Yousefi, Mohammad,Salehi, Mirmehdi Hashemi,Amiri, Mahdis,Hekmati, Malak
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- In situ generated and stabilized Pd nanoparticles by N2,N4,N6-tridodecyl-1,3,5-triazine-2,4,6-triamine (TDTAT) as a reactive and efficient catalyst for the Suzuki-Miyaura reaction in water
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In situ generated Pd nanoparticles in the presence of N2,N4,N6-tridodecyl-1,3,5-triazine-2,4,6-triamine (TDTAT) were found to be an efficient catalyst for the Suzuki-Miyaura coupling reaction in water. It seems that TDTAT not only acts as a ligand for stabilization of the produced nanoparticles, but also as a surfactant to facilate the reaction in water, and reduces Pd(ii) to Pd(0). The TEM analysis of the reaction mixture showed that Pd nanoparticles with an average size of ~5 nm are produced, which act as an efficient catalyst in the Suzuki-Miyaura coupling reaction.
- Iranpoor, Nasser,Rahimi, Sajjad,Panahi, Farhad
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- Magnetic Core–Shell to Yolk–Shell Structures in Palladium-Catalyzed Suzuki–Miyaura Reactions: Heterogeneous versus Homogeneous Nature
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This study describes a comparative investigation on the heterogeneous versus homogeneous nature of the Pd-catalyzed Suzuki–Miyaura cross-coupling reaction mechanism with specific magnetic hierarchical core–shell and yolk–shell structures. The hierarchical core–shell Fe3O4@SiO2-Pd@mCeO2 (m=mesoporous) catalyst contains a core of nonporous silica-sheltered magnetite (Fe3O4) nanoparticles (NPs), a transition layer of active palladium (Pd) NPs, and an outer shell of porous ceria (CeO2). The magnetic yolk–shell Fe3O4@h-Pd@mCeO2 (h=hollow) catalyst was prepared by selectively etching the nonporous silica interlayers. Notably, the results of the hot-filtration heterogeneity test, the effect of Pd concentration, and solid-phase poisoning, indicate that the two kinds of catalysts function in Pd-catalyzed Suzuki–Miyaura cross-coupling reactions through different catalytic mechanisms. Moreover, both catalysts demonstrated better catalytic activity than the Fe3O4@SiO2-Pd catalyst. This finding can be ascribed to the outermost CeO2 shell having a high concentration of trivalent cerium and oxygen vacancies, which gives rise to the increased electron density of Pd NPs, and a faster rate-determining step in the oxidative addition reaction for the Suzuki reaction. In addition, we propose a feasible mechanism elucidating the synergistic effect between the supporting CeO2 and active species.
- Li, Yinle,Zhang, Zhuqing,Fan, Tao,Li, Xiaoguang,Ji, Jin,Dong, Pei,Baines, Robert,Shen, Jianfeng,Ye, Mingxin
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- The air-stable and highly efficient P, N-chelated palladium(II) complexes as catalysts for the Suzuki cross-coupling reaction at room temperature
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Two air-stable P, N-chelated palladium(II) complexes have been evaluated as highly efficient and simple catalysts for Suzuki cross-coupling reaction between aryl bromides and arylboronic acids. They exhibit high activity and selectivity at room temperature.
- Guo, Mengping,Jian, Fangfang,He, Ren
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- Template-Directed Ordered Mesoporous Silica@Palladium-Containing Zinc Metal-Organic Framework Composites as Highly Efficient Suzuki Coupling Catalysts
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We report a new type of ordered mesoporous silica@Pd-containing Zn metal-organic framework composites (OMS@Pd-ZnMOF) synthesized directly by cooperative template-directed self-assembly. The growth of Pd-ZnMOF crystals on the bare surface of insitu generated silica spheres is achieved based on a surface-charge-induced epitaxial growth mechanism. The catalytic properties of the resulting OMS@Pd-ZnMOF composites can be tailored by the variation of the Pd/(Pd+Zn) molar ratio in the synthetic gel, and OMS@Pd-ZnMOF-5 % (which corresponds to 1.2wt % Pd) shows a wide substrate scope and is highly active and stable in Suzuki-Miyaura coupling reactions.
- Yang, Ying,Cong, Daoyong,Hao, Shijie
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- Palladium(ii) complexes supported by PBP and POCOP pincer ligands: A comparison of their structure, properties and catalytic activity
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A Pd(ii) chloride complex supported by a Yamashita-Nozaki PBP pincer ligand, [C6H4-1,2-(NCH2PtBu2)2B]PdCl (1a), was synthesized. The structure, properties and catalytic activity of complex 1a were compared with those of the corresponding POCOP pincer complex [C6H3-2,6-(OPtBu2)2]PdCl (2a). It was found that the Pd centre in complex 1a is more electron rich and easier to be oxidized than that in complex 2a; complex 1a is a much better catalyst for Suzuki-Miyaura cross-coupling reactions than complex 2a. Starting from complexes 1a and 2a, two series of Pd(ii) pincer complexes bearing a SH, BH4, NCS, NCSe or N3 covalent ligand, [C6H4-1,2-(NCH2PtBu2)2B]PdY (Y = SH, 1b; BH4; 1c; NCS, 1d; NCSe, 1e; and N3, 1f) and [C6H3-2,6-(OPtBu2)2]PdY (Y = SH, 2b; BH4, 2c; NCS, 2d; NCSe, 2e; and N3, 2f), were synthesized and fully characterized. Single crystal X-ray diffraction analysis indicated that the Pd centre is less tightly chelated in PBP pincer complexes. The strong σ-donor ability of the PBP pincer ligand has little influence on the structure of the covalent ligand possessing both σ-donor and π-Acceptor properties. However, the stretching vibrational frequencies of NCS, NCSe and N3 ligands and the coordination mode of the BH4 ligand are significantly different in these two types of palladium pincer complexes.
- Ding, Yazhou,Ma, Qiang-Qiang,Kang, Jiaxin,Zhang, Jie,Li, Shujun,Chen, Xuenian
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- Graphitic Carbon Nitride (g-C3N4) Supported Palladium Species: An Efficient Heterogeneous Photocatalyst Surpassing Homogeneous Thermal Heating Systems for Suzuki Coupling
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Suzuki coupling is of paramount importance in C?C coupling reactions. However, Suzuki coupling reactions are generally catalyzed by homogeneous catalysts under thermal heating, which results in difficulties in the catalyst separation and consumes a relatively large amount of energy. g-C3N4/Pd has been successfully prepared for photocatalytic Suzuki coupling reactions. The g-C3N4/Pd is prepared through the reduction of a Pd source in the presence of g-C3N4. The Pd is found to exist as Pd nanoparticles and Pd(II) species on g-C3N4. Owing to the good light absorption of g-C3N4 and the excellent catalytic activity of the Pd species, the g-C3N4/Pd shows an excellent photocatalytic performance in Suzuki coupling reactions with a TOF of 47.3 h?1, which is almost twice that of a commercial homogeneous catalyst Pd(PPh3)4, under thermal heating. Moreover, g-C3N4/Pd displays very good recyclability and wide applicability for Suzuki coupling reactions. Our findings provide a green and sustainable method for the catalysis of Suzuki coupling reactions.
- Wang, Nan,Ma, Lixia,Wang, Jing,Zhang, Yanpei,Jiang, Ruibin
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- Synthesis of a palladium complex bearing 2-phenylbenzothiazole and its application to Suzuki–Miyaura coupling reaction
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The palladacycle complex [LsPdOAc]2 bearing 2-phenyl benzothiazole was synthesized and characterized by NMR and X-ray crystallography. [LsPdOAc]2 was used as a catalyst in the Suzuki–Miyaura cross coupling reaction of 4-bromotoluene with phenylboronic acid, which resulted in a conversion of >90% with 5 mol% of the Pd complex within 10 min at 60°C.
- Kosuru, Someswara Rao,Lai, Hsin-Yu,Yang, Chien-Yi,Senadi, Gopal Chandru,Lai, Yi-Chun,Chen, Hsuan-Ying
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- New bis(N-heterocyclic carbene) palladium complex immobilized on magnetic nanoparticles: as a magnetic reusable catalyst in Suzuki-Miyaura cross coupling reaction
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A new bis(N-heterocyclic carbene) (NHC) palladium complex supported on silica coated magnetic nanoparticles (MNPs) was prepared using the reaction of synthesized Pd-NHC complex with MNPs. The Pd-NHC complex was prepared using the reaction of a hydroxyl-functionalized bis-imidazolium ionic liquid. The Pd-NHC organometallic complex was used as a heterogeneous recyclable and active catalyst in the Suzuki-Miyaura reaction and various aryl halides were coupled with arylboronic acids in order to synthesize diverse biaryls in good to excellent yields. The prepared catalyst was characterized by use of some different microscopic and spectroscopic techniques including elemental analysis, FT-IR spectroscopy, diffuse reflectance UV–Vis spectrophotometery, scanning electron microscopy (SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM) and X-ray diffraction (XRD). The Pd-NHC catalyst system is a magnetic reusable catalyst and it can be separated from the reaction mixture using an external magnetic field. The catalyst was reusable in the Suzuki-Miyaura coupling reaction at least for 6 times without significant decreasing in its catalytic activity.
- Fareghi-Alamdari, Reza,Saeedi, Mohammad S.,Panahi, Farhad
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- Synthesis of 18F-labelled biphenyls via SUZUKI cross-coupling with 4-[18F]fluoroiodobenzene
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The SUZUKI reaction of organoboron compounds with 4-[18F] fluoroiodobenzene has been developed as a novel radiolabelling technique in 18F chemistry. The cross-coupling reaction of p-tolylboronic acid with 4-[18F]fluoroiodobenzene was used to screen different palladium complexes, bases and solvents. Optimized reaction conditions (Pd 2(dba)3, Cs2CO3, acetonitrile, 60°C for 5 min) were further applied to the synthesis of various 18F-labelled biphenyls bearing different functional groups. The reaction proceeded in excellent radiochemical yields of up to 94% within 5 min while showing good compatibility to many functional groups. Copyright
- Steiniger, Bjoern,Wuest, Frank R.
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- Pd(II) Complexes Ligated by 1,3-Bis(diphenylphosphino)calix[4]arene: Preparation, X-ray Structures, and Catalyses
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syn-1,3-Bis(diphenylphosphino)-2,4-dimethoxycalix[4]arene (7) was synthesized via an Ullmann-type phosphinoylation of the syn-1,3-bis(triflate ester) (2) of p-tert-butylcalix[4]arene, followed by reduction of the phosphinoyl moieties and subsequent methylation of the remaining hydroxy groups. The treatment of diphosphine 7 with 2 molar equiv of PdCl2(MeCN)2 in benzonitrile afforded di-μ-chloro-bridged dinuclear palladium complex 8, formulated as Pd2(7)Cl4, whereas the same reaction conducted in acetonitrile with 1 molar equiv of PdCl2(MeCN)2 yielded mononuclear palladium complex 9, formulated as [Pd(7)Cl(MeCN)]Cl. Complex 9 was transformed into dicationic complex 11, formulated as [Pd(7) MeCN)2](BF4)2, by treatment with AgBF4 in dichloromethane, followed by the addition of acetonitrile. On the other hand, refluxing complex 9 in 1,2-dichloroethane yielded neutral complex 12, formulated as Pd(7)Cl2. In each of the mononuclear complexes, the palladium ion adopts a tetracoordinated square-planar geometry perpendicular to the mean plane defined by the macrocycle, and two phosphorus atoms occupy trans coordination sites. Consequently, an acetonitrile or chlorine ligand coordinates through the cavity of the calixarene, while another acetonitrile or chlorine ligand occupies the exo position. Dicationic complex 11 promoted Suzuki-Miyaura coupling between aryl chlorides and phenylboronic acid and the ring-opening reaction of an epoxide with thiophenol.
- Hirasawa, Kengo,Tanaka, Shinya,Horiuchi, Takeru,Kobayashi, Takahiro,Sato, Takumi,Morohashi, Naoya,Hattori, Tetsutaro
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- Palladium(ii) and palladium(ii)-silver(i) complexes with N-heterocyclic carbene and zwitterionic thiolate mixed ligands: synthesis, structural characterization and catalytic properties
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The integration of a geometrically rigid Pd(ii), a coordinatively monotonous N-heterocyclic carbene 1,3-dimethylimidazoline-2-ylidene (IMe), and a flexible zwitterionic thiolate 4-(trimethylammonio)benzenethiolate (Tab) affords a class of Pd-IMe-Tab complexes with various nuclearities, namely, trans-[Pd(IMe)2(Tab)2](OTf)2 (2, mononuclear), cis-[Pd(IMe)2(Tab)2](OTf)(Cl) (3a, mononuclear), cis-[Pd(IMe)2(Tab)2](PF6)2·MeCN (3b·MeCN, mononuclear), [Pd2(IMe)4(Tab)2](PF6)4·2MeCN (4·2MeCN, dinuclear) and [Pd4(IMe)4(Tab)6](OTf)6(Cl)2 (5, tetranuclear). Further presence of Ag(i) in the assembly provides a heterometallic octanuclear cluster of [Pd4Ag4(IMe)8(Tab)10](PF6)12 (6). Compounds 2-6 are formed by the reaction of trans-Pd(IMe)2Cl2 (1) with various additional reagents via different reaction pathways. These compounds are characterized by means of FT-IR, 1H and 13C NMR, ESI-MS, elemental analysis and X-ray crystallography. Notably, the skeleton of compound 5 features a [Pd4S4] parallelogram wherein each of the four Pd(ii) centers bisects the edge defined by the S atoms. The main skeleton of compound 6 is an oval-shaped Pd4Ag4S10 unit, featuring an edge-fused norbornane-like (Pd2Ag4S6) framework appended by two additional PdS2 motifs at the polar positions. Compounds 5 and 6 also feature Pd?Pd (5), Pd?Ag and Ag?Ag (6) interactions. Compound 5 as a representative example is highly effective at catalyzing Suzuki-Miyaura couplings in water, highlighting the potential of applying these types of homo- and heterometallic clusters as catalysts for organic transformations in environmentally benign media.
- Wang, Yu-Ting,Gao, Bin-Bin,Wang, Fan,Liu, Shi-Yuan,Yu, Hong,Zhang, Wen-Hua,Lang, Jian-Ping
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- High activity heterogeneous catalysts by plasma-enhanced chemical vapor deposition of volatile palladium complexes on biomorphic carbon
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Six new palladium complexes based on allyl and alkenolate ligands were synthesized and structurally characterized. Combination of delocalized allylic sp2-hybridized carbon centers and a strongly binding N?O chelating unit (e.g., 3,3,3-trifluoro(pyridin-2-yl)propen-2-ol) offered a promising combination of high volatility and thermal lability not commonly observed in noble metal precursors. Application of the new Pd compounds in thermal metal–organic and plasma-enhanced chemical vapor deposition demonstrated their clean and efficient decomposition pathways, which in conjunction with their intriguing air stability made them efficient precursors for Pd films and clusters. Plasma-enhanced chemical vapor deposition of the palladium compounds on biomorphic carbon used as a porous substrate with high surface area and interconnected channels delivered recyclable carbon-supported Pd catalysts (Pd@BioC), which showed excellent selectivity, stability, and recyclability in C–C coupling reactions.
- Czympiel, Lisa,Frank, Michael,Mettenb?rger, Andreas,Hühne, Sven-Martin,Mathur, Sanjay
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- Competitive gold/nickel transmetalation
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Transmetalation is a key method for the construction of element-element bonds. Here, we disclose the reactivity of [NiII(Ar)(I)(diphosphine)] compounds with arylgold(i) transmetalating agents, which is directly relevant to cross-coupling catalysis. Both aryl-for-iodide and unexpected aryl-for-aryl transmetalation are witnessed. Despite the strong driving force expected for Au-I bond formation, aryl scrambling can occur during transmetalation and may complicate the outcomes of attempted catalytic cross-coupling reactions.
- Austen, Brady J. H.,Demchuk, Mitchell J.,Drover, Marcus W.,Nelson, David J.,Zurakowski, Joseph A.
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supporting information
p. 68 - 71
(2021/12/29)
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- Synthesis and Bond Activation Chemistry of Palladium(II) Pincer Complexes with a Weakly Coordinating Side Arm
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A series of Pd(II) aryl complexes of a PNO-type pincer ligand bearing a weakly coordinated benzofuran side arm has been prepared. Crystallographic studies showed very long Pd-O distances of more than 2.3 ?, which is significantly longer than the Pd-O distances in structurally similar PNO-Pd complexes with an exocylic oxygen donor. Crystallographic and 19F NMR solution studies of complexes containing electron-donating (OMe) and electron-withdrawing (CF3) substituents in the position para to the benzofuran oxygen atom revealed the dependence of the Pd-O interactions on the nature of the aromatic group at the Pd center. The ability to influence these interactions by changing the electron density at the metal was demonstrated in the stoichiometric Sonogashira-type cross-coupling reactions between the Pd complexes and phenylacetylene, which proceed via a reversible aromatization/dearomatization of the pincer ligand. Complexes with the electron-poor CF3 group showed higher reactivity in comparison to their electron-neutral or -rich analogues. DFT studies of these systems provided further mechanistic insight into the origin of the observed reactivity patterns.
- Prakasham,Vigalok, Arkadi,Vedernikov, Andrei N.
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p. 634 - 641
(2022/03/02)
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- Biaryl Coupling of Aryldiazonium Salts and Arylboronic Acids Catalysed by Gold
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A gold-catalysed coupling of aryldiazonium salts with arylboronic acids is described. The reactions proceed in satisfactory yields under irradiation with blue LEDs in the presence of KF and a catalytic amount of ascorbic acid. Notably, 4-nitrobenzendiazonium tetrafluoroborate is sufficiently reactive to undergo the coupling with a variety of arylboronic acids in the absence of aryl radical initiators. The coupling is applicable for electron-donating and electron-withdrawing groups present at the para, ortho, and meta positions of both substrates.
- Medina-Mercado, Ignacio,Porcel, Susana
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- 2-Phosphinoimidazole Ligands: N-H NHC or P-N Coordination Complexes in Palladium-Catalyzed Suzuki-Miyaura Reactions of Aryl Chlorides
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We report the synthesis of two palladium 2-(dialkylphosphino)imidazole complexes and demonstrate their activity as catalysts for Suzuki-Miyaura reactions with (hetero)aryl chlorides at room temperature. Our mechanistic studies demonstrate that these palladium complexes exist as an equilibrium mixture between the P-N coordinated and N-H NHC forms of ligand. Our studies suggest that the N-H NHC form may be important for high catalytic activity in Suzuki-Miyaura reactions with aryl chlorides. These reactions proceed at or near room temperature in good to excellent yields. Heteroaryl chlorides are also reactive at lower catalyst loadings.
- Martinez, Erin E.,Larson, Alexandra J. S.,Fuller, Sydney K.,Petersen, Kathryn M.,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 1560 - 1564
(2021/05/29)
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- Pyrazole-Mediated C-H Functionalization of Arene and Heteroarenes for Aryl-(Hetero)aryl Cross-Coupling Reactions
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Herein we introduce a transition-metal-free protocol that involves a commercially available, inexpensive pyrazole molecule to conduct C-C cross-coupling reactions at room temperature via a radical pathway. Using this method, an aryldiazonium salt has been coupled to a wide range of arenes and heteroarenes including benzene, mesitylene, thiophene, furan, benzoxazole to result the corresponding biaryl products. The full reaction mechanism is elucidated along with the crystallographic probation of an active initiator species. A potassium-stabilized deprotonated pyrazole steers single-electron transfer to the substrate and behaves as an initiator for the reaction.
- Kundu, Abhishek,Dey, Dhananjay,Pal, Subhankar,Adhikari, Debashis
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p. 15665 - 15673
(2021/11/16)
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- Ni-catalyzed reductive decyanation of nitriles with ethanol as the reductant
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A nickel-catalyzed reductive decyanation of aromatic nitriles has been developed, in which the readily available and abundant ethanol was applied as the hydride donor. Various functional groups on the aromatic rings, such as alkoxyl, amino, imino and amide, were compatible in this catalytic protocol. Heteroaryl, benzylic and alkenyl nitriles were also tolerated. Mechanistic investigation indicated that ethanol provided hydride efficientlyviaβ-hydride elimination in this reductive decyanation.
- Wu, Ke,Ling, Yichen,Sun, Nan,Hu, Baoxiang,Shen, Zhenlu,Jin, Liqun,Hu, Xinquan
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supporting information
p. 2273 - 2276
(2021/03/09)
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- Nickel(II) complexes with N,O-donor thiopseudourea ligands: Syntheses, structures, and catalytic applications in Kumada–Corriu cross-coupling reactions
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Synthesis, characterization, and physical properties of benzyl-N′-(4-R-benzoyl)-N-(2,6-diisopropylphenyl)carbamimidothioates, HL1 (R = H) and HL2 (R = Cl), and their nickel(II) complexes having the general molecular formula [Ni(L1/2)2] (1 and 2) have been reported. Elemental analysis, magnetic susceptibility, solution electrical conductivity, and various spectroscopic (IR, UV–Vis, and 1H NMR) measurements were used to characterize HL1, HL2, and the two complexes (1 and 2). The molecular structures of all four compounds were determined by single-crystal X-ray crystallographic studies. The structures of HL1 and HL2 showed the imino-ketone form of both compounds. In each of 1 and 2, the six-membered chelate ring forming iminolate-O and azomethine-N donor two (L1/2)? ligands form a square-planar trans-N2O2 coordination environment around the metal center. The spectroscopic characteristics of HL1, HL2, 1, and 2 are consistent with their molecular structures. Both complexes were successfully employed as efficient catalysts in Kumada–Corriu C-C cross-coupling reactions of aryl bromides with phenylmagnesium bromide. The reactions provided biaryl products in good to excellent yields with a good substrate scope.
- Shakunthala, Kinche,Srivastava, Ankit Kumar,Babu, G. Narendra,Keesara, Srinivas,Pal, Samudranil
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- Lewis Acid-Promoted Oxidative Addition at a [Ni0(diphosphine)2] Complex: The Critical Role of a Secondary Coordination Sphere
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Oxidative addition represents a critical elementary step in myriad catalytic transformations. Here, the importance of thoughtful ligand design cannot be overstated. In this work, we report the intermolecular activation of iodobenzene (PhI) at a coordinatively saturated 18-electron [Ni0(diphosphine)2] complex bearing a Lewis acidic secondary coordination sphere. Whereas alkyl-substituted diphosphine complexes of Group 10 are known to be unreactive in such reactions, we show that [Ni0(P2BCy4)2] (P2BCy4=1,2-bis(di(3-dicyclohexylboraneyl)-propylphosphino)ethane) is competent for room-temperature PhI cleavage to give [NiII(P2BCy4)(Ph)(I)]. This difference in oxidative addition reactivity has been scrutinized computationally – an outcome that is borne out in ring-opening to provide the reactive precursor – for [Ni0(P2BCy4)2], a “boron-trapped” 16-electron κ1-diphosphine Ni(0) complex. Moreover, formation of [NiII(P2BCy4)(Ph)(I)] is inherent to the P2BCy4 secondary coordination sphere: treatment of the Lewis adduct, [Ni0(P2BCy4)2(DMAP)8] with PhI provides [NiII(P2BCy4)2(DMAP)8(I)]I via iodine-atom abstraction and not a [NiII(Ph)(I)(diphosphine)] compound – an unusual secondary sphere effect. Finally, the reactivity of [Ni0(P2BCy4)2] with 4-iodopyridine was surveyed, which resulted in a pyridyl-borane linked oligomer. The implications of these outcomes are discussed in the context of designing strongly donating, and yet labile diphosphine ligands for use in a critical bond activation step relevant to catalysis.
- Zurakowski, Joseph A.,Austen, Brady J. H.,Dufour, Maeve C.,Spasyuk, Denis M.,Nelson, David J.,Drover, Marcus W.
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supporting information
p. 16021 - 16027
(2021/10/16)
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- Porous Organic Phenanthroline-Based Polymer as an Efficient Transition-Metal-Free Heterogeneous Catalyst for Direct Aromatic C?H Activation
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Direct C?H bond transformation has been regarded as one of the most important areas in organic synthesis in both academia and industry. However, the heterogeneous transition-metal-free catalysis of direct C?H bond transformation has remained a contemporary challenge. To tackle this challenge, we designed and constructed a porous phenanthroline-based polymer (namely POP-Phen) via free radical polymerization of vinyl-functionalized phenanthroline monomers. POP-Phen shows excellent catalytic performances in transition-metal-free catalyzed C?H arylation, even better than those of the corresponding homogeneous catalyst, which is mainly attributed to the high density of catalytically active sites in the heterogeneous catalyst. Kinetic isotope experiments and spectral characterizations demonstrate the electron-transfer between the heterogeneous catalyst and the base (t-BuOK), a key step for C?H activation. We believe that this porous organic phenanthroline polymer could open a new door for the design of novel heterogeneous transition-metal-free catalysts for direct C?H activation.
- Tang, Yongquan,Chen, Fang,Wang, Sai,Sun, Qi,Meng, Xiangju,Xiao, Feng-Shou
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supporting information
p. 8684 - 8688
(2021/05/25)
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- Surface engineered Iridium-based magnetic photocatalyst paving a path towards visible light driven C-H arylation and cyanation reaction
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The report presents the fabrication and application of a highly versatile, magnetic and robust iridium based photoredox nanocatalyst. Herein, Ir(PPy)3 based photocatalyst sites have been chemically engineered over the magnetic nanoparticles to encompass the captivating features of homogeneous iridium photocatalyst with the magnetically recyclable core. A household photoreactor was designed and fabricated to achieve highly selective visible light driven oxidative C-H arylation and C-H cyanation under sustainable and ambient reaction conditions utilizing the Ir@PyBz@ASMNPs photoredox nanocatalyst. The environment friendly Ir@PyBz@ASMNPs shows excellent photocatalytic activity, broad substrate adaptability and outstanding recyclability compared to the analogous homogeneous catalysts. Indeed, the Ir@PyBz@ASMNPs possess some key features including high surface area, high iridium metal loading and excellent stability. This work is expected to enlighten and provide new insights in the rational design of high performance and recoverable photoredox nanocatalyst through surface engineering strategy.
- Gaur, Rashmi,Gawande, Manoj B.,Kaushik, Bhawna,Rana, Pooja,Sharma, Priti,Sharma, Rakesh K.,Yadav, Priya,Yadav, Sneha
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p. 297 - 308
(2021/08/23)
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- C–H Arylation of Benzene with Aryl Halides using H2 and a Water-Soluble Rh-Based Electron Storage Catalyst
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This paper reports the first example of C?H arylation of benzene under mild conditions, using H2 as an electron source {turnover numbers (TONs)=0.7–2.0 for 24 h}. The reaction depends on a Rh-based electron storage catalyst, and proceeds at room temperature and in aqueous solution. Furthermore, the H2 is inactive during the radical transfer step, greatly reducing unwanted side reactions.
- Yatabe, Takeshi,Tome, Tamon,Takahashi, Yukina,Matsumoto, Takahiro,Yoon, Ki-Seok,Nakai, Hidetaka,Ogo, Seiji
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supporting information
p. 17326 - 17330
(2021/10/29)
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- Pd Nanoparticles Embedded Into MOF-808: Synthesis, Structural Characteristics, and Catalyst Properties for the Suzuki–Miyaura Coupling Reaction
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Abstract: A heterogeneous single-site catalyst Pd@MOF-808 was successfully synthesized by water-based, green synthesis procedure. The catalytic experiments exhibited the Pd@MOF-808 promoted efficiently the Suzuki–Miyaura coupling reaction without the assistance of organic phosphine ligands at atmospheric pressure conditions. The catalyst also could be applied in the gram-scale synthesis of industrially anti-inflanmatory analgestic Fenbufen. Graphic Abstract: [Figure not available: see fulltext.]
- Li, Tang,Pang, Wan,Wang, Jie,Zhang, Xiaoli,Zhao, Zesheng
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- New Nickel-Based Catalytic System with Pincer Pyrrole-Functionalized N-Heterocyclic Carbene as Ligand for Suzuki-Miyaura Cross-Coupling Reactions
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A new catalytic system with Ni(NO3)2·6H2O as the catalyst and a pincer pyrrole-functionalized N-heterocyclic carbene as the ligand was employed in the Suzuki-Miyaura cross-coupling reactions of aryl iodides with arylboronic acids. With 5 mol% catalyst, the catalytic reactions proceeded at 160 °C, giving coupling products in isolated yields of up to 94% in short reaction times (1-4 h). The system worked efficiently with aryl iodides bearing electron-donating or electron-withdrawing groups and arylboronic acids with electron-donating groups. Steric effects were observed for both aryl iodides and arylboronic acids. It is proposed that the reactions underwent a Ni(I)/Ni(III) catalytic cycle.
- Guo, Zhifo,Lei, Xiangyang
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supporting information
(2021/09/11)
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- New biomaterials for Ni biosorption turned into catalysts for Suzuki-Miyaura cross coupling of aryl iodides in green conditions
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In parallel with increasing Ni production and utilisation, Ni pollution in the soil-water continuum has become an alarming and global problem. Solutions for removing Ni from industrial effluents have been widely investigated and biosorption has emerged as an efficient, cost-effective, scalable and sustainable alternative for water treatment. However, the biosorption capacity is limited by the chemical composition of the biomaterial and the Ni-enriched biomaterials are rarely valorised. In this work, the biosorption capacity of three abundant biomaterials with different chemical properties - water hyacinth, coffee grounds and pinecones - was studied before and after functionalization, and reached a maximum biosorption capacity of 51 mg g?1of Ni(ii). A bioinspired functionalization approach was investigated introducing carboxylate moieties and was conducted in green conditions. The Ni-enriched biomaterials were valorised by transformation into catalysts, which were characterised by MP-AES and XRPD. Their characterisation revealed a structure similar to nickel formate, and hence the Eco-Ni(HCOO)2catalysts were tested in Suzuki-Miyaura reactions. Several aryl iodides were successfully cross-coupled to phenylboronic acids using Eco-Ni(HCOO)2without any ligand, a mild and green base in a mixture of green solvents.
- Adler, Pauline,Boulanger, Clotilde,Cases, Lucie,Diliberto, Sébastien,Grison, Claude,Pelissier, Franck
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p. 28085 - 28091
(2021/09/15)
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- Near-field enhancement by plasmonic antennas for photocatalytic Suzuki-Miyaura cross-coupling reactions
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It is well documented that placing a plasmonic antenna close to catalytically active nanoparticles can enhance their catalytic activity in chemical reactions via the near-field enhancement effect. Less known is whether and how the near-field enhances the reactivity of the reactant substrates involved in these reactions. Herein, we prepared an “antenna-reactor” catalyst with Au nanoparticles absorbing light as an optical antenna and the adjacent Pd nanoparticles acting as a chemical reactor to study the near-field enhancement effect in Suzuki–Miyaura cross-coupling reaction involving various substrates. The results showed that the activity of Pd nanoparticles were significantly enhanced in the presence of Au antennas. Excessively increasing the density of Au antennas, however, suppressed the reaction due to the interaction between neighboring electromagnetic hot spots. Moreover, the near-field affected different substrates in different extents, enhancing more to reactions that involve substrates with higher electron cloud density at the reactive center. The overall effect of the near-field to the catalytic reactions was proved to be an integrated result of the effect of Au nanoparticle density and reactive center electron cloud density. This study provides enriched understanding for the near-field enhancement effect in photocatalytic reactions with various substrates, and deepened insights for new “antenna-reactor” photocatalyst design.
- Han, Chenhui,Gómez, Daniel E.,Xiao, Qi,Xu, Jingsan
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p. 205 - 211
(2021/04/27)
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- Nickel/β-CD-catalyzed Suzuki–Miyaura cross-coupling of aryl boronic acids with aryl halides in water
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In this study, a convenient nickel-catalyzed protocol has been introduced for the Suzuki–Miyaura coupling reaction. A simple mixture of Ni(II) and unfunctionalized β-cyclodextrin (β-CD) was used to cross-coupling of aryl halides with aryl boronic acids for the synthesis of biaryls in water. β-CD is a water-soluble seminatural cyclic oligosaccharide, environmentally friendly biomaterial, inexpensive, and commercially available ligand. This ligand with low solubility in usual organic solvents has been used for the synthesis of biaryls in good to excellent yields. The cross-coupling results in the presence of Ni(II)/β-CD catalytic system showed that the coupling reaction carried out with appropriate yields for both electron-rich and electron-deficient aryl halides. The coupling reaction completed in water as a green solvent. The catalyst was also recycled for four runs with a small decrease in its catalytic activity. The presented new method allows an easier and more cost-efficient synthesis of biaryls from the reaction of arylboronic acids with various aryl halides in water.
- Payamifar, Sara,Kazemi, Foad,Kaboudin, Babak
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- Ultrafine and Highly Dispersed Pd/SiO2 for Suzuki?Miyaura Cross-coupling Reactions
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Abstract: Construction of heterogeneous Pd/SiO2 catalyst via the pollution-free strategy marked strong electrostatic adsorption has been reported for the application to Suzuki–Miyaura cross-coupling reactions. The exposed negatively charged oxygen groups, which were converted from the hydroxyl groups on the surface of silica under the alkaline atmosphere, could effectively anchor palladium species to form ultrafine Pd nanoparticles (Pd NPs) with an average particle size of 1.3?nm and high dispersion (43%). Pd/SiO2 catalyst was endowed with the excellent catalytic performance which was that the yield of the Suzuki–Miyaura reaction between bromobenzene and phenylboronic acid at 40?°C was > 99% for 30?min and the TOF was ~ 80,000?h?1. The catalyst could be easily recovered and recycled by facile procedure without a significant decrease in catalytic activity, which was able to maintain the 90% yield after repeated for 8 times. In addition, a continuous flow reaction device was designed using the Pd/SiO2 catalyst to effectively improve the production efficiency of biphenyl. Graphic Abstract: Pd/SiO2 catalyst constructed with the strategy of strong electrostatic adsorption (SEA) possesses uniformly dispersed and highly exposed Pd sites which can be easily transformed into electron-deficient Pdδ+ and strengthened stability for itself due to its strong interaction with the front surface of the carrier, and has been endowed the outstanding catalytic performance for Suzuki?Miyaura cross-coupling reaction. [Figure not available: see fulltext.]
- Fan, Xizheng,Yang, Jingyi,Pang, Qingqing,Liu, Zhongyi,Zhang, Panke,Yang, Jing-He
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p. 2291 - 2301
(2021/01/04)
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- Immobilization of a Pd(ii)-containing N-heterocyclic carbene ligand on porous organic polymers: efficient and recyclable catalysts for Suzuki-Miyaura reactions
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Palladium coordinated with N-heterocyclic carbene-functionalized porous organic polymers (Pd@POPs) was successfully preparedviaScholl coupling reaction and a successive immobilization method. The protocol features simple reaction conditions, easy separation, high yield and low cost. The structure and composition of Pd@POPs were characterized by N2sorption, TGA, FT-IR, SEM, EDX, TEM, XPS and ICP. Then the obtained heterogeneous catalysts were applied in Suzuki-Miyaura coupling reaction to evaluate their catalytic performance. The Pd@POPs displayed high catalytic activity for the Suzuki-Miyaura coupling reaction in an EtOH/H2O solvent. A 0.03 mol% Pd loading was sufficient for the reaction with a high turnover number (TON) of 3220. Moreover, the catalyst was easily recovered and reused for at least six consecutive cycles without obvious loss of its initial activity.
- Gao, Xiyue,Lin, Hongwei,Liu, Cijie,Luo, Qionglin,Ouyang, Yuejun,Xiang, Bailin,Xiang, Dexuan,Yao, Huan,Zhou, Nonglin
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p. 3676 - 3680
(2021/06/17)
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- C(acyl)-C(sp2) and C(sp2)-C(sp2) Suzuki-Miyaura cross-coupling reactions using nitrile-functionalized NHC palladium complexes
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Application of N-heterocyclic carbene (NHC) palladium complexes has been successful for the modulation of C-C coupling reactions. For this purpose, a series of azolium salts (1a-f) including benzothiazolium, benzimidazolium, and imidazolium, bearing a CN-substituted benzyl moiety, and their (NHC)2PdBr2 (2a-c) and PEPPSI-type palladium (3b-f) complexes have been systematically prepared to catalyse acylative Suzuki-Miyaura coupling reaction of acyl chlorides with arylboronic acids to form benzophenone derivatives in the presence of potassium carbonate as a base and to catalyse the traditional Suzuki-Miyaura coupling reaction of bromobenzene with arylboronic acids to form biaryls. All the synthesized compounds were fully characterized by Fourier Transform Infrared (FTIR), and 1H and 13C NMR spectroscopies. X-ray diffraction studies on single crystals of 3c, 3e and 3f prove the square planar geometry. Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), metal mapping analyses and thermal gravimetric analysis (TGA) were performed to get further insights into the mechanism of the Suzuki-Miyaura cross coupling reactions. Mechanistic studies have revealed that the stability and coordination of the complexes by the CN group are achieved by the removal of pyridine from the complex in catalytic cycles. The presence of the CN group in the (NHC)Pd complexes significantly increased the catalytic activities for both reactions.
- ?akir, Sinem,Karabiyik, Hande,Kavukcu, Serdar Batikan,Rethinam, Senthil,Türkmen, Hayati
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p. 37684 - 37699
(2021/12/09)
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- Synthesis, structure and characterization of picolyl and benzyl linked biphenyl nickel NHC complexes and their catalytic activity in Suzuki-Miyaura cross-coupling reactions
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Picolyl and benzyl linked biphenyl nickel NHC complexes [NiL1Br2] (1), [NiL2]Br2 (2) [NiL3]Br2 (3) and [NiL3(N3)2] (4) were synthesized and characterized by
- Muniyappan, Nalluchamy,Junaid, Qazi Mohammad,Sabiah, Shahulhameed
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- Palladium nanoparticle supported on nitrogen-doped porous carbon: Investigation of structural properties and catalytic activity on Suzuki–Miyaura reactions
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Novel palladium-doped nanoporous carbon composite material obtained via thermolysis of amorphous zeolitic imidazolate framework (aZIF) was synthesized and used as an efficient catalyst on Suzuki–Miyaura cross-coupling reactions of aryl bromides. With this developed catalytic system, the Suzuki–Miyaura cross-coupling reaction was accomplished in aqueous solutions, and biaryls were obtained in good to excellent yields in a short reaction time. The APC-750@Pd catalyst was characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Eicroscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Brunauer–Emmett–Teller (BET) analysis tecniques. N-doped porous carbon material (NPC-1000) was synthesized by thermolysis from aZIF. Activated porous carbon material (APC-750) was fabricated via fused at 750°C with KOH from NPC-1000. The APC-750@Pd was obtained as a result of the interaction of APC-750 and PdCl2 in deionized water. The cross-coupling reaction of different aryl bromides with phenylboronic acid was investigated to show the potential of the APC-750@Pd in the Suzuki–Miyaura cross-coupling reactions. The APC-750@Pd catalyst could be recycled at least five times with a 15% loss of catalytic efficiency in this catalytic system.
- Bu?day, Nesrin,Alt?n, Serdar,Ya?ar, Sedat
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- Ligand-free Suzuki-Miyaura cross-coupling with low Pd content: rapid development by a fluorescence-based high-throughput screening method
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Suzuki-Miyaura (SM) cross-coupling is one of the most effective strategies for carbon-carbon bond formation, but previous methods have several drawbacks, such as the requirement of complicated ligands, toxic organic solvents, and high-content-Pd catalysts. Thus, in this study, a highly efficient SM cross-coupling was developed using metal oxide catalysts: 0.02 mol% Pd, aqueous solvent, no ligand, and room temperature. Metal oxides containing low Pd content (ppm scale) were prepared by a simple co-precipitation method and used as a catalyst for the SM reaction. A fluorescence-based high-throughput screening (HTS) method was developed for the rapid evaluation of catalytic activity and reaction conditions. Among the various metal oxides, Pd/Fe2O3showed the highest activity for the SM reaction. After further optimization by HTS, various biaryl compounds were obtained under optimal conditions: Pd/Fe2O3(0.02 mol% Pd) in aqueous ethanol at mild temperature without any ligands.
- Lim, Taeho,Ryoo, Jeong Yup,Jang, Mingyeong,Han, Min Su
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p. 1009 - 1016
(2021/02/16)
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- Impact of Solvent and Their Contaminants on Pd/C Catalyzed Suzuki-Miyaura Cross-Coupling Reactions
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The aim of this work was to understand if solvent contaminants can interfere in Suzuki’s cross-coupling reactions and if it can explain the lack of robustness in industrial processes. For this purpose, several parameters were tested on the industrial model reaction between 2-bromonaphthalene and phenylboronic acid catalyzed by Pd/C. Best results were obtained using THF as solvent. Traces of the precursors of the used solvents, such as 2,3-dihydrofurane or maleic anhydride (100–300 ppm related to the solvent) strongly poisoned the reaction, decreasing the conversion significantly. This means that to ensure robust production, solvent quality must be analyzed at the ppm level. Fortunately, addition of triphenylphosphine can circumvent the catalyst poisoning.
- de Lambert de Boisjan, Alexandre,Allemann, Christophe,Fadini, Luca
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- From the grafting of NHC-based Pd(II) complexes onto TiO2 to the in situ generation of Mott-Schottky heterojunctions: The boosting effect in the Suzuki-Miyaura reaction. Do the evolved Pd NPs act as reservoirs?
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The assumption that the real active species involved in the Suzuki-Miyaura reaction are homogeneous, heterogeneous or both is often proposed. However a lack of characterization of the true catalytic entities and their monitoring makes assumptions somewhat elusive. Here, with the aim of getting new insights into the formation of active species in the Suzuki-Miyaura reaction, a family of palladium(II) complexes bearing bis(NHC) ligands was synthesized for immobilization at the surface of TiO2. The studies reveal that once the complexes are anchored onto TiO2, the mechanism governing the catalytic reaction is different from that observed for the non-anchored complexes. All complexes evolved to Pd NPs at the surface of TiO2 under reaction conditions and released Pd species in the liquid phase. Also, this reactivity was boosted by the in situ generation of Mott-Schottky heterojunctions, opening new routes towards the design of heterogenized catalysts for their further implementation in reverse-flow reactors.
- De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
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p. 133 - 147
(2021/05/10)
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- A Bis (BICAAC) Palladium(II) Complex: Synthesis and Implementation as Catalyst in Heck-Mizoroki and Suzuki-Miyaura Cross Coupling Reactions
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Carbenes are one of the most appealing, well-explored, and exciting ligands in modern chemistry due to their tunable stereoelectronic properties and a wide area of applications. A palladium complex (BICAAC)2PdCl2 with a recently discovered cyclic (alkyl)(amino)carbene having bicyclo[2.2.2] octane skeleton (BICAAC) was synthesized and characterized. The enhanced σ-donating and π-accepting ability of this carbene lend a hand to form a robust Pd-carbene bond, which allowed us to probe its reactivity as a precatalyst in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions with low catalyst loading in open-air conditions. The diverse range of substrates was explored for both the cross-coupling reactions. To get a better understanding of the catalytic reactions, several analytical techniques such as field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and powder X-ray diffraction were employed in a conclusive manner.
- Chakrabortty, Soumyadeep,Kaur, Mandeep,Adhikari, Manu,Manar, Krishna K.,Singh, Sanjay
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supporting information
p. 6209 - 6217
(2021/05/06)
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- Palladium nanoparticles encapsulated in polyimide nanofibers: An efficient and recyclable catalyst for coupling reaction
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In this study, palladium-encapsulated poly(amic acid) (Pd@PAA) nanofibers were prepared by electrospinning, followed by thermal imidization to synthesize palladium-encapsulated polyimide (Pd@PI) nanofibers. Scanning electron microscopy (SEM) images confirmed the preparation of uniform and smooth Pd@PAA and Pd@PI nanofibers. Thermogravimetric analysis (TGA) results reveal that the Pd@PI nanofibers possessed excellent thermal stability. The dispersion of palladium nanoparticles in the polyimide nanofibers was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The catalysis results show that this Pd@PI fibrous catalyst was very efficient to catalyze the cross-coupling reactions of aromatic iodides with n-butyl acrylate (Heck reaction) or phenylboronic acid derivatives (Suzuki reaction) to afford the desired products in good to excellent yields. Moreover, the Pd@PI catalyst could be easily separated and recovered from the reaction mixture by simple filtration due to the regular fibrous structure and reused for 10 times for both Heck and Suzuki reactions without obvious loss of its initial catalytic activity. Thus, the Pd@PI nanofiber catalyst holds great potential in chemical industry in terms of its excellent catalytic activity and stability.
- Du, Yijun,Gou, Faliang,Gao, Danning,Liu, Zhifeng,Shao, Linjun,Qi, Chenze
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- Efficient and Economical Preparation of Hypercrosslinked Polymers-palladium Based on Schiff Base as Recyclable Catalyst for Suzuki-Miyaura Reactions
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A novel hypercrosslinked polymer (HCP) was prepared via Friedel-Crafts alkylation reaction of Schiff base with benzene and formaldehyde dimethyl acetal (FDA) promoted by FeCl3. The HCP was then metalated with Pd(II) to form heterogeneous catalyst. The protocol featured low cost, mild conditions, readily available materials, easy separation and high yield. Physicochemical methods, including IR, N2 sorption, ICP, TGA, XPS, SEM, EDX, and TEM, were used to characterize the catalyst structure and composition. The results reveal that the heterogeneous catalyst possesses high specific surface area, large pore volume, good chemical and thermal stability, and highly dispersed palladium. The heterogeneous catalysts were applied in Suzuki-Miyaura coupling reaction to evaluate their catalytic performance. The experiments reflected that the HCPs-Pd(OAc)2 was an efficient catalyst for Suzuki-Miyaura reactions with the yield of biaryl up to 99%, while the TON could reach 2250. The reusability test showed the catalyst was easily recovered and reused for at least six times without obvious decrease in activity.
- Gao, Xiyue,Lin, Hongwei,Liu, Shasha,Luo, Qionglin,Ouyang, Yuejun,Xiang, Bailin,Xiang, Dexuan,Yao, Huan,Zhang, Li
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supporting information
p. 1879 - 1882
(2021/10/29)
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- Palladium-catalyzed denitrogenative cross-coupling of aryl halides with arylhydrazines under mild reaction conditions
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A greener approach for the synthesis of various functionalized biaryl frameworks in good to excellent yield through palladium-catalyzed denitrogenative cross-coupling of aryl halides with arylhydrazines under mild reaction conditions was developed. Catalytic system is free from the aid of expensive ligands and external oxidants. Biogenically prepared palladium nanoparticles (Pd NPs) immobilized cellulose based dip catalyst displayed excellent reactivity and selectivity toward the synthesis of a broad array of symmetrical and unsymmetrical biaryls through C–N bond cleavage in air as green oxidant. In addition, recyclability in denitrogenative cross-coupling reaction was also studied which showed excellent recycling performance and the dip catalyst remained stable even after several reuses. Thus, our newly developed strategy was successfully applied for constructing wide-ranging functional groups tolerated biaryls using arylhydrazines and aryl halides as coupling partners which is most useful for practical applications in synthetic chemistry.
- Kempasiddaiah, Manjunatha,Kandathil, Vishal,Dateer, Ramesh B.,Sasidhar,Patil, Shivaputra A.,Patil, Siddappa A.
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p. 273 - 281
(2021/01/12)
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- Synthesis of arylboronates via the Pd-catalyzed desulfitative coupling reaction of sodium arylsulfinates with bis(pinacolato)diboron
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The desulfitative borylation reaction of sodium arylsulfinates with bis(pinacolato)diboron or bis(neopentylglycolato)diboron under palladium catalysis has been developed, allowing selective C-B bond formation to give arylboronates with a range of functional groups in moderate to good yields under mild reaction conditions. A gram-scale preparation as well as the cascade Suzuki-Miyaura cross-coupling of arylboronates demonstrated the potential practical utility in organic synthesis.
- Qiu, Di,Li, Songyi,Yue, Guanglu,Mao, Jinshan,Xu, Bei,Yuan, Xinyu,Ye, Fei
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supporting information
(2021/11/04)
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- Cobalt-Catalyzed Coupling of Aryl Chlorides with Aryl Boron Esters Activated by Alkoxides
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The cobalt-catalyzed Suzuki biaryl cross-coupling of aryl chloride substrates with aryl boron reagents, activated with more commonly used bases, remained a significant unmet challenge in the race to replace platinum group metal catalysts with Earth-abundant metal alternatives. We now show that this highly desirable process can be realized using alkoxide bases, provided the right counterion is employed, strict stoichiometric control of the base is maintained with respect to the aryl boron reagent, and the correct boron ester is selected. Potassium tert-butoxide works well, but any excess of the base first inhibits and then poisons the catalyst. Lithium tert-butoxide performs very poorly, while even catalytic amounts of lithium additives also poison the catalyst. Meanwhile, a neopentane diol-based boron ester is required for best performance. As well as delivering this sought-after transformation, we have undertaken detailed mechanistic and computational investigations to probe the possible mechanism of the reaction and help explain the unexpected experimental observations.
- Tailor, Sanita B.,Manzotti, Mattia,Smith, Gavin J.,Davis, Sean A.,Bedford, Robin B.
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p. 3856 - 3866
(2021/04/07)
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- Pd-NHCs Enabled Suzuki-Miyaura Cross-Coupling of Arylhydrazines via C–N Bond Cleavage
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We describe a highly efficient protocol for cross-coupling of phenylhydrazines with arylboronic acids by Pd-NHCs under aerobic reaction condition. A series of well-defined Pd-NHCs complexes were evaluated and the relationship between the structure and the catalytic properties was investigated. It was disclosed that the Pd-PEPPSI-IPr proved to be the robust precatalyst, providing access to a range of (hetero)biaryls in good to excellent yields.
- Zeng, Xiao-Xiao,Li, Dong-Hui,Zhou, Zhen,Xu, Chang,Liu, Feng-Shou
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supporting information
(2021/03/01)
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- Role of dppf Monoxide in the Transmetalation Step of the Suzuki-Miyaura Coupling Reaction
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Diphosphine ligands are frequently used in palladium-catalyzed Suzuki-Miyaura (S-M) reactions. Despite their widespread application in both academic and industrial settings, their role in the B-to-Pd transmetalation has not been firmly established. We combined electrochemistry, NMR spectroscopy, and DFT calculations to elucidate the role of dppf (1,1′-bis(diphenylphosphino)ferrocene) in this key elementary step of the S-M reaction. We observed that excess dppf inhibits transmetalation involving PhB(OH)2 and dppf-ligated arylpalladium(II) complexes, while an optimal [base]/[PhB(OH)2] ratio maximizes the concentration of a [Pd-O-B] key intermediate. In situ oxidation of dppf to the diphosphine monoxide dppfO can take place in the presence of base, leading to dppfO-ligated arylpalladium(II) complexes, which readily undergo transmetalation at room temperature. These findings suggest guidelines for the rational optimization of diphosphine-promoted S-M reactions.
- Payard, Pierre-Adrien,Bohn, Antoine,Tocqueville, Damien,Jaouadi, Khaoula,Escoude, Emile,Ajig, Sanaa,Dethoor, Annie,Gontard, Geoffrey,Perego, Luca Alessandro,Vitale, Maxime,Ciofini, Ilaria,Wagschal, Simon,Grimaud, Laurence
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supporting information
p. 1120 - 1128
(2021/05/06)
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- Vinyl Thianthrenium Tetrafluoroborate: A Practical and Versatile Vinylating Reagent Made from Ethylene
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The use of vinyl electrophiles in synthesis has been hampered by the lack of access to a suitable reagent that is practical and of appropriate reactivity. In this work we introduce a vinyl thianthrenium salt as an effective vinylating reagent. The bench-stable, crystalline reagent can be readily prepared from ethylene gas at atmospheric pressure in one step and is broadly useful in the annulation chemistry of (hetero)cycles, N-vinylation of heterocyclic compounds, and palladium-catalyzed cross-coupling reactions. The structural features of the thianthrene core enable a distinct synthesis and reactivity profile, unprecedented for other vinyl sulfonium derivatives.
- Juliá, Fabio,Paulus, Fritz,Ritter, Tobias,Yan, Jiyao
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supporting information
p. 12992 - 12998
(2021/09/03)
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- Lipids as versatile solvents for chemical synthesis
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Development of safe, renewable, cheap and versatile solvents is a longstanding challenge in chemistry. We show here that vegetable oils and related systems can become prominent solvents for organic synthesis. Suzuki-Miyaura, Hiyama, Stille, Sonogashira and Heck cross-couplings proceed with quantitative yields in a range of vegetable oils, fish oil, butter and waxes used as solvents. Appropriate methodologies for high-throughput screening and sustainable isolation techniques applicable for vegetable oils and related lipids are presented.
- Bayer, Annette,Gevorgyan, Ashot,Hopmann, Kathrin H.
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supporting information
p. 7219 - 7227
(2021/09/28)
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- Feeding Carbonylation with CO2via the Synergy of Single-Site/Nanocluster Catalysts in a Photosensitizing MOF
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Solar-driven carbonylation with CO2 replacing toxic CO as a C1 source is of considerable interest; however it remains a great challenge due to the inert CO2 molecule. Herein, we integrate cobalt single-site and ultrafine CuPd nanocluster catalysts into a
- Fu, Shanshan,Guo, Guang-Chen,Guo, Song,Lu, Tong-Bu,Yao, Shuang,Yuan, Wenjuan,Zhang, Zhi-Ming
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p. 20792 - 20801
(2021/12/14)
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- Transition metal catalyzed nitro-aromatic denitration method
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The invention provides a transition metal catalyzed nitro-aromatic denitration method, which comprises the following steps: in a nitrogen atmosphere, taking nitro-aromatic as a substrate in an organicsolvent, reacting under the action of alkali and a reducing agent under the action of a transition metal catalyst and a ligand, and carrying out column chromatography separation to obtain an aromaticcompound. The method can directly convert nitro aromatic hydrocarbon into corresponding aromatic hydrocarbon compounds, is high in catalytic efficiency, low in cost and convenient to operate, and canbe compatible with various functional groups. In addition, the directional reduction nitro group, position and number of the nitro group of the polynitro compound are regulated and controlled throughthe proportion and addition amount of the reducing agent and the catalytic system, so that the directional conversion of the polynitro group is realized.
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Paragraph 0027; 0029-0032; 0041-0044
(2020/08/18)
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- Stille coupling method for catalyzing aromatic nitro compound by transition metal
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The invention provides a Stille coupling method for catalyzing aromatic nitro compound by transition metal. According to the method, in a nitrogen protection atmosphere, an aromatic nitro compound andan organic tin compound are used as substrates in an organic solvent, a cross coupling reaction is carried out under the action of an alkali under the action of a transition metal catalyst and a ligand, and the aromatic compound is obtained through a column chromatography or recrystallization method. The method is easy to operate, low in price, high in product conversion rate and good in substrate applicability; the method can be used for synthesizing a series of aromatic compounds, and the compounds have wide application values in the fields of pesticides, medicines, materials and the like.
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Paragraph 0025; 0028; 0040-0042
(2020/08/02)
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- Activator-Promoted Aryl Halide-Dependent Chemoselective Buchwald-Hartwig and Suzuki-Miyaura Type Cross-Coupling Reactions
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Herein, we report the development of aryl halide-dependent chemoselective reactions, viz., the Buchwald-Hartwig type coupling reaction of an aryl iodide with an arylboronic acid and an aryl amine in the presence of a heterogeneous and reusable nickel catalyst and the Suzuki-Miyaura type coupling of an aryl chloride under similar conditions. Control experiments revealed that the presence of stoichiometric amounts of the phenylboronic acid/ester and aryl amine are essential for both reactions. NMR and XAFS studies suggested the formation of a boron-amine "ate"complex.
- Dhital, Raghu N.,Hashizume, Daisuke,Hu, Hao,Ishii, Rikako,Sato, Takuma,Sen, Abhijit,Takaya, Hikaru,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information
(2020/06/29)
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- Highly Active Heterogeneous PdCl2/MOF Catalyst for Suzuki–Miyaura Cross-Coupling Reactions of Aryl Chloride
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The exploration of highly efficient Pd/MOF heterogeneous catalyst system for the Suzuki–Miyaura cross-coupling (SMC) reactions of aryl chlorides is still challenging. Herein, a PdCl2/UiO-67-bpydc was successfully synthesized by immobilizing a low amount of PdCl2 onto the zirconium-based MOF (UiO-67-bpydc). PdCl2/UiO-67-bpydc showed excellent catalytic performance and good recycle ability for the SMC reaction of aryl chlorides under an ambient condition. Furthermore, PdCl2/UiO-67-bpydc retains the high catalytic activity even after five cycles, and exhibited excellent substrate size selectivity.
- Gong, Xue-Fang,Zhang, Ling-Yan,Zhang, Hui-Xin,Cui, Yu-Meng,Jin, Fen-Chun,Liu, Yu,Zhai, Yu-Feng,Li, Jin-Heng,Liu, Gui-Yan,Zeng, Yong-Fei
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p. 1336 - 1341
(2020/07/06)
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- Multifunctional Crown-5-calix[4]arene-based Phase-Transfer Catalysts for Aromatic 18F-Fluorination
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Methylated bis-triethylene glycolic crown-5-calix[4]arene (M-BTC5A) as a phase-transfer catalyst showed the best performance among other analogues and even conventional Kryptofix 222 in the nucleophilic aromatic 18F-fluorination of diaryliodonium tosylate precursors owing to (i) the efficient release of reactive "naked"[18F]fluoride, (ii) the high stabilization of the precursor in the reaction, and, presumably, (iii) the ease of access between the precursor and the K18F/M-BTC5A complex facilitated by π-πinteractions. [18F]Flumazenil was produced in high radiochemical yield using M-BTC5A.
- Lee, Won Chang,Kang, Seok Min,Lee, Byung Chul,Kim, Sang Eun,Kim, Dong Wook
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p. 9551 - 9555
(2020/12/21)
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- The Synthesis and Catalytic Activity of New Mixed NHC-Phosphite Nickel(0) Complexes
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Herein we describe the synthesis and isolation of the first low-valent NHC-phosphite nickel complexes of general formula Ni(NHC)[P(OAr)3]2. These three-coordinate Ni(0) compounds were fully characterized, including by X-ray crystallography that highlighted their trigonal planar geometry. The representative complex Ni(IMes)[P(OPh)3]2 was used to show that a phosphite ligand is readily substituted in the presence of an aldehyde or nitrile. These stoichiometric studies then led to an investigation of their catalytic properties in the Suzuki-Miyaura cross-coupling reactions between aryl tosylates and aryl boronic acids, a first for such a NHC-Ni catalyst. Finally, mechanistic investigations led to the isolation of a well-defined oxidative addition product.
- Dorta, Reto,Duczynski, Jeremy,Moggach, Stephen A.,Sobolev, Alexandre N.,Stewart, Scott G.
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supporting information
(2020/01/21)
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- Small organic molecules with tailored structures: Initiators in the transition-metal-free C-H arylation of unactivated arenes
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Simple, small organic molecules containing nitrogen and oxygen atoms in their structures have been disclosed to catalyze transition-metal-free C-H arylation of unactivated arenes with aryl iodides in the presence of tBuOK. In this article, an optimized catalytically active molecule, (2-(methylamino)phenyl)methanol, was designed. A broad range of aryl iodides could be converted into the corresponding arylated products at 100 °C over 24 h with good to excellent yields. Mechanistic experiments verified that radicals participated in this catalytic transformation and that the cleavage of the aromatic C-H bond was not the rate determining step. A K+ capture experiment by 18-crown-6 emphasized the significance of the cation species of the strong base. Fourier transform infrared spectroscopy proved that the catalytic system was activated by the hydrogen bonds between small organic molecules and tBuOK. Also, a clear mechanism was proposed. This transition-metal-free method affords a promising system for efficient and inexpensive synthesis of biaryls via a user-friendly approach, as confirmed by scale-up experiments.
- Chen, Suqing,Chen, Wenjun,Chen, Yu,Liu, Zhenghui,Mu, Tiancheng,Wang, Peng,Yan, Zhenzhong
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p. 14500 - 14509
(2020/04/27)
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- NaH-mediated direct C-H arylation in the presence of 1,10-phenanthroline
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Transition-metal-free coupling of haloarenes with unactivated arenes has been developed in the presence of NaH and 1,10-phenanthroline. Various haloarenes bearing methyl, methoxy, halogen (fluoride, chloride, and bromide), cyano, trifluoromethyl, ester, and amide groups can be cross-coupled with unactivated arenes, or heteroarenes in this reaction.
- Nozawa-Kumada, Kanako,Iwakawa, Yuki,Onuma, So,Shigeno, Masanori,Kondo, Yoshinori
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supporting information
p. 7773 - 7776
(2020/07/27)
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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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- Ligand-free Suzuki coupling reaction with highly recyclable ionic palladium catalyst, Ti1-xPdxO2-x (x?=?0.03)
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We synthesized a recyclable palladium ionic catalyst, Ti0.97Pd0.03O1.97, using a solution combustion method (SCM), and characterized by XRD and Rietveld refinement. The synthesized Pd ionic catalyst is stable, insensitive to moisture and air, and easy to handle. The new catalyst has exhibited a phenomenal result for the Suzuki-Miyaura cross-coupling reaction with a broad substrate scope, and the reaction proceeds in an aqueous medium. The new catalyst proved beneficial and produced excellent yields irrespective of aryl halide used in the reaction (electron-rich or electron-poor or heterocyclic compounds) and shown a turnover frequency (TOF) of 14–25 h?1 for different reactions. The catalyst was coated on a cordierite monolith (Mg2Al4Si5O18), which enhanced the applicability of the catalyst, and made the handling and recycling of the catalyst very easy. Suzuki Miyaura reaction was carried out using both Pd-powder catalysts as well as the Pd-coated honeycomb, which gave almost similar results. We have demonstrated the recyclability of Pd coated cordierite monolith and shown the superiority of the catalyst over the other Pd catalysts for the Suzuki-Miyaura reaction.
- Bhat K, Shrikanth,Lanke, Veeranjaneyulu,Prasad, Jagadeesh Dasappa,Prabhu, Kandikere Ramaiah
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- Immobilized Pd on a NHC functionalized metal–organic framework MIL-101(Cr): an efficient heterogeneous catalyst in Suzuki?Miyaura coupling reaction in water
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A novel Pd?NHC functionalized metal–organic framework (MOF) based on MIL-101(Cr) was synthesized and used as an efficient heterogeneous catalyst in the C-C bond formation reactions. Using this heterogeneous Pd catalyst system, the Suzuki?Miyaura coupling reaction was accomplished well in water, and coupling products were obtained in good to excellent yields in short reaction time. The Pd?NHC?MIL-101(Cr) was characterized using some different techniques, including Fourier transform-infrared, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy, inductively coupled plasma and elemental analysis. The microscopic techniques showed the discrete octahedron structure of MIL-101(Cr), which is also stable after chemical modification process to prepare the catalyst system. The TEM images of the catalyst showed the existence of palladium nanoparticles immobilized in the structure of the catalyst, while no reducing agent was used. It seems that the NHC groups and imidazolium moieties in the structure of the MOF can reduce Pd (II) to Pd (0) species. This modified MOF substrate can also prevent aggregation of Pd nanoparticles, resulting in high stability of them in organic transformation. The Pd?NHC?MIL-101(Cr) catalyst system could be simply extracted from the reaction mixture, providing an efficient synthetic method for the synthesis of biaryls derivatives using the aforementioned coupling reaction. The Pd?NHC?MIL-101(Cr) catalyst could be recycled in this organic reaction with almost consistent catalytic efficiency.
- Khalafi-Nezhad, Ali,Niknam, Esmaeil,Panahi, Farhad
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- Self-Assembling Supramolecular Hybrid Hydrogel Beads
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With the goal of imposing shape and structure on supramolecular gels, we combine a low-molecular-weight gelator (LMWG) with the polymer gelator (PG) calcium alginate in a hybrid hydrogel. By imposing thermal and temporal control of the orthogonal gelation methods, the system either forms an extended interpenetrating network or core–shell-structured gel beads—a rare example of a supramolecular gel formulated inside discrete gel spheres. The self-assembled LMWG retains its unique properties within the beads, such as remediating PdII and reducing it in situ to yield catalytically active Pd0 nanoparticles. A single PdNP-loaded gel bead can catalyse the Suzuki–Miyaura reaction, constituting a simple and easy-to-use reaction-dosing form. These uniquely shaped and structured LMWG-filled gel beads are a versatile platform technology with great potential in a range of applications.
- Piras, Carmen C.,Slavik, Petr,Smith, David K.
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supporting information
p. 853 - 859
(2019/12/24)
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- 4-Amino-1,2,4-triazoles-3-thiones and 1,3,4-oxadiazoles-2-thiones·palladium(II) recoverable complexes as catalysts in the sustainable Suzuki-Miyaura cross-coupling reaction
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The Suzuki-Miyaura cross-coupling reaction using 4-amino-1,2,4-triazoles and 1,3,4-oxadiazoles-2-thiones·palladium (II) is studied. The reaction is optimized and the most appropriate catalytic complex is tested with several aryl halides, boronic acids in an environmentally benign solvent system (H2O/EtOH). The recovery of the catalytic species is also surveyed because of the nature of the employed solvent. A domino process is efficiently carried out following the standard conditions. Several surface parameters of the ligands are analyzed and the resulting values are extrapolated to the insoluble palladium catalyst.
- Chehrouri, Manel,Moreno-Cabrerizo, Cristina,Othman, Adil A.,Chabour, Ihssene,Ferrándiz-Saperas, Marcos,Sempere, Inmaculada,D?nda?, H. Ali,de Gracia Retamosa,Sansano, José M.
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- Development of a tethered Palladium-BODIPY dual catalyst for enhanced photo- And thermally activated catalysis, and for promoting sequential reactivity
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In recent years there has been a growing interest in merging different types of catalysis to create new multistep catalytic processes. However, the majority of reported dual catalysis strategies use a mixture of individual catalysts, with limited reports of dual catalysis reactions where the different catalysts are combined in a single compound. This work reports the synthesis of a tethered palladium-BODIPY dual catalyst to enable increased synergistic interactions between the catalytic centres. Detailed analysis, including single crystal X-ray crystallography, absorption, fluorescence, and phosphorescence measurements, and kinetic analyses to determine singlet oxygen quantum yields, confirm that chemical tethering results in a significant increase in the photocatalytic potential of the palladium-BODIPY dual catalyst, relative to the parent BODIPY chromophore. Interestingly, the palladium-BODIPY complex also exhibited rare long-lived room temperature phosphorescence. Catalytic applications of the palladium-BODIPY dual catalyst indicate that chemical tethering increases the reactivity of the catalytic centres for both photocatalytic oxidation of thioanisole and palladium catalysed Suzuki- Miyaura cross coupling, highlighting that enhancements in both photo and thermally activated catalysis can be achieved on chemical tethering. In addition, the dual catalytic potential of the palladium-BODIPY catalyst was demonstrated using a representative sequential photocatalytic oxidation-cross coupling reaction.
- Wang, Danfeng,Solomon, Nicholas S.D.,Pernik, Indrek,Messerle, Barbara A.,Keaveney, Sinead T.
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p. 979 - 986
(2020/05/08)
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