- Synthesis and catalytic activity in suzuki coupling of nickel complexes bearing n -butyl- and triethoxysilylpropyl-substituted NHC ligands: Toward the heterogenization of molecular catalysts
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Cyclopentadienyl N-heterocyclic carbene (NHC) nickel complexes of general formula [Ni(R-NHC-nBu)XCp] [R-NHC-nBu = 1-butyl-3-methyl-, 1-isopropyl-3-butyl-, 1-phenyl-3-butyl-, 1-(2,4,6-trimethylphenyl)-3-butyl-, 1-(2,6- diisopropylphenyl)-3-butyl-imidazol-2-ylidene; X = Cl or I; Cp = η5-C5H5], which bear an n-butyl side-chain attached to one of the nitrogen atoms of the NHC ring, were synthesized as models for trialkoxysilylpropyl-substituted complexes. They were prepared by the direct reactions of nickelocene with the corresponding imidazolium salts (R-NHC-nBuHX). The new complexes [Ni(Me-NHC-nBu)ClCp] (1a), [Ni(iPr-NHC-nBu)ClCp] (1b), [Ni(Ph-NHC-nBu)ICp] (1c), [Ni(Mes-NHC-nBu)ICp] (1d), and [Ni(iPr2Ph-NHC-nBu)ICp] (1e) were obtained in moderate to good yields and were fully characterized by standard spectroscopic techniques, and in the cases of 1a,b,d,e by single-crystal X-ray crystallography. The bulky electron-rich pentamethylcyclopentadienyl derivatives, [Ni(Mes-NHC-nBu) ICp*] (2d) and [Ni(iPr2Ph-NHC-nBu)ICp*] (2e) (Cp* = η5-C5Me5), were prepared from reactions of in situ prepared [Ni(acac)Cp*] with the corresponding carbene precursors. Both Cp* complexes were also fully characterized spectroscopically, and their structures were established by single-crystal X-ray crystallography. All new complexes catalyzed the Suzuki-Miyaura cross-coupling of phenylboronic acid with aryl halides in the absence of cocatalysts or reductants. However, the small dialkyl-substituted species 1a and 1b proved to be the least efficient. In addition, in contrast to our previous results with the closely related diaryl-substituted species [Ni(Ar2NHC)LCp?] (L = Cl-, NCMe (PF6-); Cp? = Cp, Cp*), in which complexes that bear the electron-rich Cp* ligand were much more active than those bearing the Cp ligand, no substantial catalytic behavior differences were observed between the Cp complexes 1d,e and their Cp* counterparts 2d,e. A TOF of up to 352 h-1, a so far unprecedented rate for nickel(II) complexes under similar conditions, was even observed with the Cp complex 1d. In view of these encouraging results, the triethoxysilylpropyl-substituted analogue of 1d, [Ni(Mes-NHC-TES)ClCp] (1d-TES) (Mes-NHC-TES = 1-(2,4,6-trimethylphenyl)-3-[3-(triethoxysilyl)propyl]imidazol-2- ylidene), was prepared, fully characterized, and tested catalytically. As it showed similar catalytic activity to 1d, it was heterogenized on alumina to give 1d-Al. The latter species, however, exhibited a greatly reduced catalytic activity compared to 1d and 1d-TES. Possible reasons for both the excellent activities of 1d and 1d-TES and the disappointing activity of 1d-Al are discussed.
- Oertel, Anna Magdalena,Ritleng, Vincent,Chetcuti, Michael J.
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- Covalently stabilized Pd clusters in microporous polyphenylene: An efficient catalyst for Suzuki reactions under aerobic conditions
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A novel catalyst composed of a microporous polyphenylene network and covalently stabilized Pd clusters (Pd/MPP) for highly efficient Suzuki-Miyaura coupling is synthesized with an in-situ one-pot chemical approach, through the catalytic trimerization of 1,3,5-triethynylbenzene. The unique Pd/MPP cluster exhibits very high catalytic activity for a broad scope of Suzuki-Miyaura reactions with short reaction time, good yield, and high turnover number and turnover frequency values, even in aqueous media under aerobic conditions. The strong covalent interaction between Pd and MPP network prevents the agglomeration or leaching of Pd clusters and enables the catalyst to remain highly active, even after a number of cycles. Copyright
- Song, Qi,Jia, Yuying,Luo, Bin,He, Haiyong,Zhi, Linjie
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- Porphyrenediynes: synthesis and cyclization of meso-enediynylporphyrins
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Synthetic methodology to prepare porphyrinylethynyl enediynes has been developed. Compared to phenylethynyl derivatives, a bulky porphyrinic substituent on the alkyne significantly increases the thermal barrier toward Bergman cyclization and leads to multiple photolysis products.
- Spence, John D.,Hargrove, Amanda E.,Crampton, Hannah L.,Thomas, David W.
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- Construction of covalent organic framework for catalysis: Pd/COF-LZU1 in Suzuki-Miyaura coupling reaction
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Covalent organic frameworks (COFs) are crystalline porous solids with well-defined two- or three-dimensional molecular structures. Although the structural regularity provides this new type of porous material with high potentials in catalysis, no example has been presented so far. Herein, we report the first application of a new COF material, COF-LZU1, for highly efficient catalysis. The easily prepared imine-linked COF-LZU1 possesses a two-dimensional eclipsed layered-sheet structure, making its incorporation with metal ions feasible. Via a simple post-treatment, a Pd(II)-containing COF, Pd/COF-LZU1, was accordingly synthesized, which showed excellent catalytic activity in catalyzing the Suzuki-Miyaura coupling reaction. The superior utility of Pd/COF-LZU1 in catalysis was elucidated by the broad scope of the reactants and the excellent yields (96-98%) of the reaction products, together with the high stability and easy recyclability of the catalyst. We expect that our approach will further boost research on designing and employing functional COF materials for catalysis.
- Ding, San-Yuan,Gao, Jia,Wang, Qiong,Zhang, Yuan,Song, Wei-Guo,Su, Cheng-Yong,Wang, Wei
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- 'Awaken' aryl sulfonyl fluoride: a new partner in the Suzuki-Miyaura coupling reaction
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An example of the activation of the -SO2F group, which is traditionally considered a stable group even in the presence of a transition metal, is described using a novel partner in the Suzuki-Miyaura coupling reaction catalyzed by Pd(OAc)2 and Ruphos as ligands. The products showed good to outstanding yields and broad functional group compatibility under optimal conditions. The sequential synthesis of non-symmetric terphenyls and the gram grade process highlight the approach's synthetic utility. DFT calculations have shown that Pd0 prefers to insert between C-S bonds rather than S-F bonds. This journal is
- Ding, Chengrong,Guan, Chenfei,Miao, Huihui,Zhang, Guofu,Zhao, Yiyong
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supporting information
p. 3560 - 3564
(2022/03/07)
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- Nickel-Catalyzed Direct Cross-Coupling of Aryl Sulfonium Salt with Aryl Bromide
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The direct cross-couplings of aryl sulfonium salts with aryl halides could be achieved by using nickel as a reaction catalyst. The reactions proceeded efficiently via C-S bond activation in the presence of magnesium turnings and lithium chloride in THF at ambient temperature to afford the corresponding biaryls in moderate to good yields, potentially serving as an attractive alternative to conventional cross-coupling reactions employing preprepared organometallic reagents.
- Ma, Na-Na,Ren, Jing-Ao,Liu, Xiang,Chu, Xue-Qiang,Rao, Weidong,Shen, Zhi-Liang
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supporting information
p. 1953 - 1957
(2022/03/27)
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- Synthesis of ultrafine AuPd bimetallic nanoparticles using a magnetite-cored poly(propyleneimine) dendrimer template and its sustainable catalysis of the Suzuki coupling reaction
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The poly(propyleneimine) PPI dendrimer with active amino groups and specific voids is an excellent template for the encapsulation and stabilization of size and shape-controlled metal nanoparticles. The magnetite-cored PPI dendrimer up to third generation was synthesized by a divergent method in our previous report. Bimetallic nanoparticles are more advantageous than monometallic nanoparticles in catalysis due to their synergistic effect between two metals, especially Au and Pd nanoparticles. Herein, we present the synthesis of highly monodispersed ultrafine AuPd bimetallic nanoparticles of size 3-6 nm using the magnetic-cored PPI dendrimer through a facile and convenient method without external stabilizers. The formation of the monodispersed bimetallic nanoparticles on the dendritic entity was confirmed through HRTEM, HRSEM, EDAX, XRD, XPS and VSM. The excellent structural behavior of the magnetic-cored PPI dendrimers proves their ability to encapsulate AuPd bimetallic nanoparticles, and also attain better dispersibility, stability, and improved efficacy compared to conventional dendrimer-encapsulated metal nanoparticles. Most predominantly, it was isolated by simple magnetic attraction. TheAuPd@PPI@Fe3O4/SiO2nanomaterial was utilized as a potential green catalyst in the Suzuki coupling reaction under ambient reaction conditions with greater reactivity and stability. Coupling products were characterized by1H and13C NMR. This material retained its catalytic activity in the coupling reaction for up to eight consecutive catalytic cycles.
- Lakshmi, Kannappan,Rangasamy, Rajmohan,Selvaraj, Mari
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p. 14227 - 14235
(2021/08/16)
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- Fe3O4-SAHPG-Pd0 nanoparticles: A ligand-free and low Pd loading quasiheterogeneous catalyst active for mild Suzuki–Miyaura coupling and C-H activation of pyrimidine cores
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This paper reports a green magnetic quasiheterogeneous efficient palladium catalyst in which Pd0 nanoparticles have been immobilized in self-assembled hyperbranched polyglycidole (SAHPG)-coated magnetic Fe3O4 nanoparticles (Fe3O4-SAHPG-Pd0). This catalyst has been used for effective ligandless Pd catalyzed Suzuki–Miyaura coupling reactions of different aryl halides with substituted boronic acids at room temperature and in aqueous media. Herein, SAHPG is used as support; it also acts as a reducing agent and stabilizer to promote the transformation of PdII to Pd0 nanoparticles. Also, this environmental friendly quasiheterogeneous catalyst is employed for the first time in the synthesis of new pyrimido[4,5-b]indoles via oxidative addition/C-H activation reactions on the pyrimidine rings, which were obtained with higher yield and faster than when Pd(OAc)2 was used as the catalyst. Interestingly, the above-mentioned catalyst could be recovered in a facile manner from the reaction mixture by applying an external magnet device and recycled several times with no significant decrease in the catalytic activity.
- Azizollahi, Hamid,Eshghi, Hossein,García-López, José-Antonio
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- Molecular engineered palladium single atom catalysts with an M-C1N3subunit for Suzuki coupling
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Single atom catalysis has emerged as a powerful technique for catalysis due to its outstanding performance and atom economy. Controlling the hybridization of the atom with its environment is crucial in determining the selectivity and/or yield of the reaction. However, the single atom environment is usually ill-defined and hard to predict because the pyrolysis process used in preparing SACs damages the original status of the precursors in the catalyst preparation. A molecular engineering approach to synthesize single atom catalysts (SACs) on a heterogeneous template provides a strategy to make SACs with a highly uniform coordinating environment. Herein, we report the preparation of a molecular engineered Pd single atom catalyst with a pre-defined M-N3C1 coordination (Pd-N3C1-SAC) using a structure-rigid Pd-N3C1 porphyrin as the precursor, which shows more efficient Suzuki coupling compared with the SAC with Pd-N4 coordination. The origin of the high activity of the Pd-N3C1-SAC is revealed through density functional theory calculations, where a lower reaction barrier for the rate-determining oxidative addition is identified. This journal is
- Liu, Jia,Chen, Zhongxin,Liu, Cuibo,Zhang, Bao,Du, Yonghua,Liu, Chen-Fei,Ma, Lu,Xi, Shibo,Li, Runlai,Zhao, Xiaoxu,Song, Jingting,Sui, Xin Zhi,Yu, Wei,Miao, Ling,Jiang, Jianjun,Koh, Ming Joo,Loh, Kian Ping
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supporting information
p. 11427 - 11432
(2021/05/19)
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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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- Evaluation of P-bridged biaryl phosphine ligands in palladium-catalysed Suzuki-Miyaura cross-coupling reactions
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A family of biaryl phosphacyclic ligands derived from phobane and phosphatrioxa-adamantane frameworks is described. The rigid biaryl phosphacycles are efficient for Suzuki-Miyaura cross-coupling of aryl bromides and chlorides. In particular, coupling reactions of the challenging sterically hindered and heterocyclic substrates were viable at room temperature.
- Holzapfel, Cedric W.,Lamola, Jairus L.,Maumela, Munaka Christopher,Moshapo, Paseka T.
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p. 26883 - 26891
(2021/08/17)
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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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- Pd(OAc)2-biuret: A highly efficient, low cost and phosphine-free catalyst system for biaryl synthesis under aerobic conditions at room temperature
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A highly efficient, less expensive and phosphine-free protocol for the Suzuki-Miyaura cross-coupling reactions of aryl halides and aryl boronic acids in iPrOH-H2O solvent under aerobic conditions has been developed. The results demonstrate that the biuret played a crucial role and making this protocol highly efficient. The Pd(OAc)2-biuret system exhibited superb catalytic activity towards the Suzuki-Miyaura cross-coupling reaction of a wide range of aryl halides with aryl boronic acids at room temperature, giving high yields even under very low catalytic loading. This system offers an attractive alternative to the existing protocols since the reaction proceeds in green solvent at room temperature with working simplicity, shorter reaction time, cost-effectiveness and provides the desired products in high yields. The effect of solvent, base as well as catalyst loading on the cross-coupling reaction of aryl halide with arylboronic acid is also described.
- Saikia, Bishwajit
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- Aminomethylpyridinequinones as new ligands for PEPPSI-type complexes
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A set of six new catalysts possessing quinone moieties in a pyridine ligand was synthesized and fully characterized by standard analytical techniques, including X-Ray crystallography. The results obtained in Suzuki and Mizoroki–Heck cross-coupling reactions catalyzed by quinone-based compounds were comparable to these obtained in the presence of the original PEPPSI complex designed by Organ. DFT calculations allow to see the structural and electronic factors to describe their similarity. On the other hand, steric maps and NCI plots were the tools to have a more global view of the systems studied, leaving the sphere of reactivity around the metal.
- Gajda, Roman,Poater, Albert,Brotons-Rufes, Artur,Planer, Sebastian,Wo?niak, Krzysztof,Grela, Karol,Kajetanowicz, Anna
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p. 138 - 156
(2021/03/22)
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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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- 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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- 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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- Selective synthesis of 1-halonaphthalenes by copper-catalyzed benzannulation
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The synthesis of 1-halonaphthalenes by the Cu-catalyzed benzannulation reaction of 2-(phenylethynyl)benzaldehyde and alkynes in the presence of the halogen reagents such as NBS, NCS, and NIS, was developed. This protocol afforded various type of 1-halonap
- Umeda, Rui,Ueda, Ryo,Tanaka, Taiki,Hayashi, Akitsugu,Ikeshita, Masahiro,Suzuki, Shuichi,Naota, Takeshi,Nishiyama, Yutaka
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supporting information
(2020/12/29)
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- Arylketones as Aryl Donors in Palladium-Catalyzed Suzuki-Miyaura Couplings
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Herein, we report the arylation, alkylation, and alkenylation of aryl ketones via a palladium-catalyzed Suzuki-Miyaura cross-coupling reaction. The use of the pyridine-oxazoline ligand is the key to the cleavage of the unstrained C-C bond. The late-stage arylation of aryl ketones derived from drugs and natural products demonstrated the synthetic utility of this protocol.
- Wang, Zhen-Yu,Ma, Biao,Xu, Hui,Wang, Xing,Zhang, Xu,Dai, Hui-Xiong
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p. 8291 - 8295
(2021/11/13)
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- Cobalt?NHC Catalyzed C(sp2)?C(sp3) and C(sp2)?C(sp2) Kumada Cross-Coupling of Aryl Tosylates with Alkyl and Aryl Grignard Reagents
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The first cobalt-catalyzed cross-coupling of aryl tosylates with alkyl and aryl Grignard reagents is reported. The catalytic system uses CoF3 and NHCs (NHC=N-heterocyclic carbene) as ancillary ligands. The reaction proceeds via highly selective C?O bond functionalization, leading to the corresponding products in up to 98 % yield. The employment of alkyl Grignard reagents allows to achieve a rare C(sp2)?C(sp3) cross-coupling of C?O electrophiles, circumventing isomerization and β-hydride elimination problems. The use of aryl Grignards leads to the formation of biaryls. The C?O cross-coupling sets the stage for a sequential cross-coupling by exploiting the orthogonal selectivity of the catalytic system.
- Piontek, Aleksandra,Och?dzan-Siod?ak, Wioletta,Bisz, Elwira,Szostak, Michal
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p. 202 - 206
(2020/12/01)
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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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- MeOTf/KI-catalyzed efficient synthesis of 2-arylnaphthalenesviacyclodimerization of styrene oxides
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The MeOTf/KI-catalyzed synthesis of 2-arylnaphthalene derivatives from aryl ethylene oxides in alcohol under ambient conditions is described. The present protocol has a higher atom efficiency and wider substrate applicability with excellent yields. The reaction proceeded using the aryl ethylene oxides to give 2-arylnaphthalenes either in homo-coupling or in cross-coupling. The reaction could also be carried out at the gram scale in minutes.
- Chen, Chao,Xi, Chanjuan,Zhang, Zeyu,Zou, Song
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supporting information
p. 8559 - 8565
(2021/10/20)
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- Ligand and Base Free Synthesis of Biaryls from Aryl Halides in Aqueous Media with Recyclable Ti0.97Pd0.03O1.97 Catalyst
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Abstract: Facile protocol for the synthesis of biaryls from aryl halides in presence of magnesium metal without prior formation of organometallic intermediate has been exploited. Irrespective of aqueous medium, Ti0.97Pd0.03O1.97 catalyst supports C–C bond formation reaction in presence of metals rather than dehalogenation without any additives. Homocoupling of 16 different aryl halides furnished corresponding biphenyls in good yield with better functional group tolerance. The recovery of the catalyst was carried out by employing catalyst coated cordierite monolith up to 7th cycle with high yields. A new approach for the cross-coupling reaction is also attempted. Graphic Abstract: [Figure not available: see fulltext.]
- Prasanna,Bhat, Shrikanth K.,Usha,Hegde
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p. 3313 - 3322
(2021/03/04)
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- The Anionic Pathway in the Nickel-Catalysed Cross-Coupling of Aryl Ethers
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The Ni-catalysed cross-coupling of aryl ethers is a powerful method to forge new C?C and C?heteroatom bonds. However, the inert C(sp2)?O bond means that a canonical mechanism that relies on the oxidative addition of the aryl ether to a Ni0 centre is thermodynamically and kinetically unfavourable, which suggests that alternative mechanisms may be involved. Here, we provide spectroscopic and structural insights into the anionic pathway, which relies on the formation of electron-rich hetero-bimetallic nickelates by adding organometallic nucleophiles to a Ni0 centre. Assessing the rich co-complexation chemistry between Ni(COD)2 and PhLi has led to the structures and solution-state chemistry of a diverse family of catalytically competent lithium nickelates being unveiled. In addition, we demonstrate dramatic solvent and donor effects, which suggest that the cooperative activation of the aryl ether substrate by Ni0-ate complexes plays a key role in the catalytic cycle.
- Borys, Andryj M.,Hevia, Eva
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supporting information
p. 24659 - 24667
(2021/10/20)
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- METHOD FOR SYNTHESIZING BORONATE ESTER COMPOUND, SODIUM SALT OF BORONATE ESTER COMPOUND, AND METHOD FOR SYNTHESIZING THE SAME
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An object is to establish a technology with which a boronate ester compound can be easily and efficiently synthesized at a low cost with a small number of steps without the need for a complex chemical method and reagents that need to be carefully handled. A further object is to establish a sodium salt of a boronate ester compound that is a novel compound and a technology for synthesizing the sodium salt of a boronate ester compound. Provided are a sodium salt of a boronate ester compound and a method for synthesizing a boronate ester compound or a sodium salt of a boronate ester compound that includes reacting, in a reaction solvent, an organic chloride with a dispersion product obtained by dispersing sodium in a dispersion solvent to obtain an organic sodium compound, and reacting the obtained organic sodium compound with a borate ester compound to obtain a boronate ester compound or a sodium salt of a boronate ester compound.
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Paragraph 0126
(2021/03/13)
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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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- Tetraethylphosphorodiamidate-Directed Metalation Group: Directed Ortho and Remote Metalation, Cross Coupling, and Remote Phospha Anionic Fries Rearrangement Reactions
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The linked directed ortho and remote metalation (DoM and DreM) and cross-coupling reactions of aryl phosphorodiamidates (Ar-OP(O)(NEt2)2) is reported. The o-iodo and o-boronato aryl tetraethylphosphorodiamidates 3, prepared by DoM, undergo orthogonal Ni- and Pd-catalyzed Suzuki-Miyaura cross coupling to furnish biaryls 4 and 5 in good to excellent yields. Silicon group protection of biaryl 4 via DoM followed by previously unobserved DreM phospha anionic Fries rearrangement affords biaryls 11 which, under acidic conditions, furnish oxaphosphorine oxides 12.
- Alessi, Manlio,Blackburn, Thomas,Patel, Jignesh J.,Sawinski, Hannah,Snieckus, Victor
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- Designing a bifunctional metal-organic framework by tandem post-synthetic modifications; an efficient and recyclable catalyst for Suzuki-Miyaura cross-coupling reaction
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A new Cu/Pd bimetallic Cu-MOF-[Pd] was synthesized through covalent, dative and inorganic post-synthetic modifications. In order to achieve the Cu-MOF-[Pd], Zn-MOF (TMU-17-NH2) was initially selected and fabricated by grafting of salicylaldehyde via Schiff-base formation followed by complex formation with Pd(II). Then, the as-synthesis MOF, Zn-MOF-[Pd], was subjected as 3D-template to obtain Cu-MOF-[Pd] by transmetalation process. The Cu-MOF-[Pd] was characterized by FT-IR spectroscopy, atomic absorption spectroscopy (AAS), field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (PXRD), energy dispersive X-ray spectroscopy (EDS), and EDS mapping techniques. The feasibility of using Cu-MOF-[Pd] as a highly active recoverable catalyst was confirmed in the Suzuki–Miyaura cross-coupling reaction in a mixed water/ethanol solvent. The results show that this novel nano-composite could serve as an efficient bimetallic heterogeneous catalyst and reuse at least for 5 times without loss in activity.
- Hamadi, Hosein,Nobakht, Valiollah,Salahshournia, Behrang
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- Synthesis of Enaminone-Pd(II) Complexes and Their Application in Catalysing Aqueous Suzuki-Miyaura Cross Coupling Reaction
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A series of Pd(II)-enaminone complexes, termed Pd(eao)2, have been synthesized and characterized. The investigation on the catalytic activities of these new Pd(II)-reagents has proved that the Pd(eao)2-1 possesses excellent catalytic activity for the Suzuki- Miyaura cross coupling reactions of aryl bromides/chlorides with aryl/vinyl boronic acids in the environmentally benign media of aqueous PEG400 at low loading (5 mol‰). The superiority of this Pd(II)-reagent to those commercial Pd(II) and Pd(0) catalysts in catalyzing the reactions has been confirmed by parallel experiments. What's more, Pd(eao)2-2 has been found as a practical catalyst for the homo-coupling reactions of aryl boronic acids.
- Fu, Leiqing,Cao, Xiaoji,Wan, Jie-Ping,Liu, Yunyun
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p. 254 - 258
(2020/01/25)
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- A simple, efficient and green approach for the synthesis of palladium nanoparticles using Oxytocin: Application for ligand free Suzuki reaction and total synthesis of aspongpyrazine A
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A novel, green, eco-friendly and cost-effective biological route for the synthesis of palladium nanoparticles (PdNPs) from commercially available palladium chloride and easily isolable hormone Oxytocin as reducing agent is reported here. Characterization of PdNPs were done using various techniques, UV–visible spectroscopy, XRD, TEM and EDAX, characterization data confirmed the formation of Pd0 from Pd2+. The size of synthesized PdNPs were 15–20 nm. The scope of Pd nanoparticles was studied for the C–C bond formation Suzuki reaction. The catalytic activity of PdNPs was excellent in short reaction time and reaction works in green solvent water as well as catalyst can be recycled. Simple and efficient approach for total synthesis of aspongpyrazine A of the recently isolated natural substance is described.
- Bendre, Ameya D.,Kodam, Kisan M.,Patil, Viraj P.,Terdale, Santosh S.,Waghmode, Suresh B.
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supporting information
(2020/01/13)
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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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- Suzuki-Miyaura coupling catalyzed by a Ni(II) PNP pincer complex: Scope and mechanistic insights
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The nickel(II) pincer complex, [NiCl(PhPNP)] (PhPNP = anion of 2,5-bis(diphenylphosphinomethyl)pyrrole), has been employed as a precatalyst for the Suzuki-Miyaura cross-coupling reaction of aryl halides and boronic acids. Both electron-rich and electron-deficient aromatic bromides were found to undergo coupling with boronic acids in modest yield at elevated temperature in the presence of K3PO4·H2O. Preliminary mechanistic studies of the reaction identified a novel species formulated as the boronate complex, [Ni(OB{OH}{2-tolyl})(PhPNP)], which most likely represents a catalyst deactivation pathway. The productive catalytic cycle was found to be most consistent with a Ni(I)/Ni(III) process where the boronic acid serves as both reductant and nucleophile in the presence of base.
- Madera, Justin,Slattery, Megan,Arman, Hadi D.,Tonzetich, Zachary J.
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- CeO2/Pd Nanoparticles Incorporated Fly Ash Zeolite: An Efficient and Recyclable Catalyst for Csp2-Csp2 Bond Formation Reactions
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The catalytic activity of CeO2 and palladium nanoparticles supported fly ash zeolite (CeO2/Pd@FAZ) for Csp2-Csp2 bond formation was studied. CeO2/Pd@FAZ was characterized by FTIR, XRD, EDAX and TEM studies. In the Suzuki-Miyauracross-coupling reaction, biphenyl derivatives with excellent yields were obtained, and the reaction conditions were optimized. The catalytic activity was explored using a wide variety of diversely substituted aryl bromides and chlorides with aryl boronic acid under optimized reaction conditions. The recyclability of the catalyst was established for three cycles, with the conversion rate from 99 to 40percent, which gained the advantage of heterogeneous catalysis.
- Sheeba Thavamani, Seth,Sudharsan, Murugesan,Santhana Mariya, Anitha,Suresh, Devarajan,Jose Amali, Arlin,Rajeswari, Sanniyasi,Peter Amaladhas, Thomas
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- Monosubstituted, Anionic Imidazolyl Ligands from N?H NHC Precursors and Their Activity in Pd-Catalyzed Cross-Coupling Reactions
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We report that treatment of several 2-diphenylphosphinoimidazoles with Pd(II) salts generates monosubstituted N?H NHC?Pd complexes via insertion into the C?P bond. Removal of the N?H proton in situ leads to anionic (X-type) or imidazolyl-Pd complexes that are highly stable and catalytically active, achieving up to 340,000 turnovers at 1 ppm catalyst loading in Suzuki-Miyaura reactions. DFT-calculated Tolman electronic parameters for the sterically small ligands suggest that these ligands are significantly more donating than traditional NHCs, which provides a rationale for rapid cross-coupling catalysis. Excellent reactivity is also demonstrated in Sonogashira reactions. (Figure presented.).
- Clark, Kyle J.,Ess, Daniel H.,Jensen, Christopher A.,Kenney, Karissa C.,Larson, Alexandra J. S.,Martinez, Erin E.,Michaelis, David J.,Nazari, S. Hadi,Smith, Stacey J.,Valdivia-Berroeta, Gabriel A.
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supporting information
(2020/07/06)
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- Sun-light-driven suzuki-miyaura cross-coupling using a novel superparamagnetic metal-organic framework catalyst
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A prominent catalytic activity for sun-light driven Suzuki-Miyaura cross-coupling reaction has been shown in the presence of superparamagnetic core-shell metal-organic framework (Fe3O4@Ni-Co-BTC NPs) (with particle size 10–47 nm) and unique bimetallic core-shell nanostructure). Various aryl halides with electron-donating or electron-withdrawing substituents were coupled with different arylboronic acids towards corresponding products at ambient temperature in H2O. The results of photocatalysis demonstrate that Fe3O4@Ni-Co-BTC NPs is a good photocatalyst under sun light irradiation with high efficiency, chemoselectivity and functional group tolerance. This magnetic separable nanostructured catalyst can be reused more than six times with minimal loss of catalytic activity rendering this catalyst long-term stability. The results acquired in the present study can serve as inspiration for the further exploitation of the sun-light-driven cross-coupling reaction under mild conditions.
- Taraghi, Sina,Akhlaghinia, Batool,Pourali, Ali Reza
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- A recyclable heterogeneous nanocatalyst of copper-grafted natural asphalt sulfonate (NAS@Cu): Characterization, synthesis and application in the Suzuki-Miyaura coupling reaction
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A new and efficient nanocatalyst was identified, synthesized and introduced and its catalytic activity was investigated in the Suzuki coupling reaction. This nanocatalyst can be synthesized by sulfonating natural asphalt as a high-carbon, cost-effective and accessible substrate using high-concentration sulfuric acid. After being neutralized by NaOH, it was transformed into sodium natural asphalt sulfonate (Na-NAS). Ultimately, the nanocatalyst was synthesized through a displacement reaction of sodium natural asphalt sulfonate with copper chloride. The solid derived (NAS@Cu) was identified using Transmission Electron Microscopy (TEM), Energy Dispersive Spectroscopy (EDS), Scanning Electron Microscopy (SEM), N2 sorption isotherms, Inductively Coupled Plasma (ICP), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Atomic Absorption Spectrometry (AAS) and Fourier-transform Infrared spectroscopy (FT-IR). NAS@Cu is a heterogeneous catalyst with advantages such as having a high specific surface area, being environmentally friendly and economically sound and simple purification and separation from the reaction mixture. Moreover, the nano-catalyst was recycled several times without any significant changes in its catalytic properties. This journal is
- Kohzadi, Homa,Soleiman-Beigi, Mohammad
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p. 12134 - 12142
(2020/08/17)
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- NHC-Nickel Catalyzed C-N Bond Cleavage of Mono-protected Anilines for C-C Cross-Coupling
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A Ni-catalyzed aryl C-N bond cleavage of mono-protected anilines, N-arylsulfonamides, has been developed. A new N-heterocyclic carbene derived from benzoimidazole shows high reactivity for the C-N cleavage/C-C cross-coupling reaction. The ortho-directing group is not required to break the C-N bond of sulfonyl-protected anilines, which are not limited to π-extended anilines. The mechanistic studies have revealed that a sulfamidomagnesium salt is the key coupling intermediate.
- Xia, Ji-Bao,Zhang, Zheng-Bing
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p. 9609 - 9613
(2020/12/21)
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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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- Dichloroimidazolidinedione-activated one-pot Suzuki–Miyaura cross-coupling of phenols
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The first general method for the Suzuki-type cross-coupling of phenols with aryl boronic acids using dichloroimidazolidinedione (DCID) as a new reagent is presented. In the presence of DCID and Pd/metal–organic framework (MOF), coupling of aryl boronic acids with a wide range of phenols, was carried out smoothly in tetrahydrofuran (THF) at reflux conditions to afford the cross-coupling products in good to excellent yields. The structures of all compounds were corroborated by 1H- and 13C-NMR. A plausible mechanism for this type of reaction is proposed.
- Madankar, Kamelia,Mokhtari, Javad,Mirjafary, Zohreh
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- Decarbonylative Suzuki-Miyaura Cross-Coupling of Aroyl Chlorides
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Herein, we report a catalyst system for Pd-catalyzed decarbonylative Suzuki-Miyaura cross-coupling of aroyl chlorides with boronic acids to furnish biaryls. This strategy is suitable for a broad range of common aroyl chlorides and boronic acids. The synthetic utility is highlighted in the direct late-stage functionalization of pharmaceuticals and natural products capitalizing on the presence of carboxylic acid moiety. Extensive mechanistic and DFT studies provide key insight into the reaction mechanism and high decarbonylative cross-coupling selectivity.
- Zhou, Tongliang,Xie, Pei-Pei,Ji, Chong-Lei,Hong, Xin,Szostak, Michal
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supporting information
p. 6434 - 6440
(2020/09/02)
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- Cross-Electrophile C(sp2)?Si Coupling of Vinyl Chlorosilanes
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The cross-electrophile coupling has become a powerful tool for C?C bond formation, but its potential for forging the C?Si bond remains unexplored. Here we report a cross-electrophile Csp2-Si coupling reaction of vinyl/aryl electrophiles with vinyl chlorosilanes. This new protocol offers an approach for facile and precise synthesis of organosilanes with high molecular diversity and complexity from readily available materials. The reaction proceeds under mild and non-basic conditions, demonstrating a high step economy, broad substrate scope, wide functionality tolerance, and easy scalability. The synthetic utility of the method is shown by its efficient accessing of silicon bioisosteres, the design of new BCB-monomers, and studies on the Hiyama cross-coupling of vinylsilane products.
- Duan, Jicheng,Kang, Shaolin,Liu, Xue-Yuan,Qi, Liangliang,Shu, Xing-Zhong,Wang, Ke,Xu, Guang-Li
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p. 23083 - 23088
(2020/12/09)
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- Shuttling Catalyst: Facilitating C?C Bond Formation via Cross-Couplings with a Thermoresponsive Polymeric Ligand
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A poly(ethylene glycol) (PEG) linked ortho-MeO-phenyldicyclohexylphosphine (MeO-WePhos) ligand has been synthesized to promote Pd-catalyzed carbon-carbon bond formation by cross-couplings including Sonogashira, Heck, Hiyama and Stille reactions, providing corresponding (hetero)aryl substituted alkynes, alkenes and bi(hetero)aryls in good to excellent isolated yields with low Pd loadings. Facilitated by the lower critical solution temperature behaviour of the polymeric monophosphine ligand, the metal-complex could rapidly shuttle between organic and water phases as regulated by temperature, enabling highly efficient catalyst recycling via a simple phase separation. The chemical structure of ligand was determined by matrix-assisted laser desorption/ionization-time of flight mass spectrometry, nuclear magnetic resonance spectrometry and size-exclusion chromatography measurements. Notably, as demonstrated by the inductively coupled plasma-atomic emission spectrometry measurement, 98% Pd was kept in the water phase after 6 cycles of catalyst recycling experiments. Given the profound impact of transition-metal-catalyzed covalent bond formation and the increasing demand of sustainable chemistry, this work provides an alternative method to conduct cross-couplings with a polymeric shuttling catalyst.
- Wang, Erfei,Zhang, Jiawei,Zhong, Zhuoran,Chen, Kaixuan,Chen, Mao
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p. 419 - 423
(2020/01/08)
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- Dual Nickel-/Palladium-Catalyzed Reductive Cross-Coupling Reactions between Two Phenol Derivatives
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Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance of phenols. Here, we report a dual nickel-/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2′-disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allows for straightforward late-stage functionalization, illustrated with examples such as ezetimibe and tyrosine.
- Xiong, Baojian,Li, Yue,Wei, Yin,Kramer, S?ren,Lian, Zhong
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supporting information
p. 6334 - 6338
(2020/09/02)
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- Synthesis of Biaryls via Decarbonylative Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Aryl Anhydrides
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Transition metal-catalyzed cross-couplings have been widely employed in the synthesis of many important molecules in synthetic chemistry for the construction of diverse C-C bonds. Conventional cross-coupling reactions require active electrophilic coupling partners, such as organohalides or sulfonates, which are not environmentally friendly enough. Herein, we disclose the first nickel-catalyzed Suzuki-Miyaura cross-coupling of aryl anhydrides and arylboronic acids for the synthesis of biaryls in a decarbonylation manner. The reaction tolerates a wide range of electron-withdrawing, electron-neutral, and electron-donating substituents in this process.
- Zhou, Jing-Ya,Liu, Rui-Qing,Wang, Cheng-Yi,Zhu, Yong-Ming
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p. 14149 - 14157
(2020/11/13)
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- Switching from biaryl formation to amidation with convoluted polymeric nickel catalysis
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A stable, reusable, and insoluble poly(4-vinyl-pyridine) nickel catalyst (P4VP-NiCl2) was prepared through the molecular convolution of poly(4-vinylpyridine) (P4VP) and nickel chloride. We proposed a coordination structure of the Ni center in the precatalyst based on elemental analysis and Ni K-edge XANES, and we confirmed that it is consistent with Ni K-edge EXAFS. The Suzuki?Miyaura-type coupling of aryl halides and arylboronic esters proceeded using P4VP-NiCl2 (0.1 mol % Ni) to give the corresponding biaryl compounds in up to 94% yield. Surprisingly, when the same reaction of aryl halides and arylboronic acid/ester was carried out in the presence of amides, the amidation proceeded predominantly to give the corresponding arylamides in up to 99% yield. In contrast, the reaction of aryl halides and amides in the absence of arylboronic acid/ester did not proceed. P4VP-NiCl2 successfully catalyzed the lactamization for preparing phenanthridinone. P4VP-NiCl2 was reused five times without significant loss of catalytic activity. Pharmaceuticals, natural products, and biologically active compounds were synthesized efficiently using P4VPNiCl2 catalysis. Nickel contamination in the prepared pharmaceutical compounds was not detected by ICP-MS analysis. The reaction was scaled to multigrams without any loss of chemical yield. Mechanistic studies for both Suzuki?Miyaura and amidation were performed.
- Sen, Abhijit,Dhital, Raghu N.,Sato, Takuma,Ohno, Aya,Yamada, Yoichi M.A.
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p. 14410 - 14418
(2020/12/21)
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- Phenanthroline-based microporous organic polymer as a platform for an immobilized palladium catalyst for organic transformations
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Porous organic polymers have attracted significant attention owing to their large specific surface area, excellent chemical and thermal stability, and controllable skeletons. phenanthroline-based microporous organic polymer (Phen-MOP) has been synthesized via a cost-effective method based on the Scholl reaction. The Phen-MOP polymer exhibits high surface area and good stability. Owing to the phenanthroline skeleton embedding into the microporous polymer framework, the Phen-MOP can serve as a platform to support a transition metal catalyst. After being post-modified with palladium acetate, the synthesized Phen-Pd-MOP framework can serve as a highly efficient heterogeneous catalyst for the Suzuki-Miyaura coupling reaction and the Heck coupling reaction. Moreover, the Phen-Pd-MOP catalyst could be reused at least 10-12 times without any significant loss of the catalytic activity.
- Wang, Chang-An,Nie, Kun,Song, Guo-Dong,Li, Yan-Wei,Han, Yin-Feng
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p. 8239 - 8245
(2019/03/21)
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- Room-Temperature Aqueous Suzuki-Miyaura Cross-Coupling Reactions Catalyzed via a Recyclable Palladium@Halloysite Nanocomposite
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A reliable method for encapsulation of palladium nanoparticles (6-8 nm particles) in halloysite (Pd@Hal) has been developed. The Pd@Hal was found to be a highly efficient room-temperature catalyst for Suzuki-Miyaura cross-coupling reactions that gave high yields of a diverse array of coupling products in 5:2 n-PrOH/H2O within 1 h. The catalytic system was remarkably effective with a broad substrate scope. In addition, the catalyst was easily recovered and recycled without a significant loss of catalytic activity.
- Hamdi, Jumanah,Blanco, Alexis A.,Diehl, Brooke,Wiley, John B.,Trudell, Mark L.
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supporting information
p. 3471 - 3475
(2019/04/25)
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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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- Biochar as heterogeneous support for immobilization of Pd as efficient and reusable biocatalyst in C–C coupling reactions
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Biochar is a stable and carbon-rich solid which has a high density of carbonyl, hydroxyl and carboxylic acid functional groups on its surface. In this work, the surface of biochar nanoparticles (BNPs) was modified with 3-choloropropyltrimtoxysilane and further 2-(thiophen-2-yl)-1H-benzo[d]imidazole was anchored on its surface. Then, palladium nanoparticles were fabricated on the surface of the modified BNPs and further the catalytic application was studied as recyclable biocatalyst in carbon–carbon coupling reactions such as Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. The structure of the catalyst was characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, X-ray diffraction and atomic absorption spectroscopy. The catalyst can be reused several times without a decrease in its catalytic efficiency. In addition to the several advantages reported, application of biochar as catalyst support for the first time is a major novelty of the present work.
- Moradi, Parisa,Hajjami, Maryam,Valizadeh-Kakhki, Fatemeh
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- Catalytic reactivity of the complexes [Pd{(Ph2P)2N(tBu)-P,P′}X2], X = Cl, Br, I, in the Suzuki-Miyaura C?C coupling reaction: Probing effects of the halogeno ligand X? and the ligand's tBu group
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The synthesis, as well as the spectroscopic and structural characterization of three analogous palladium(II) complexes, [Pd{(Ph2P)2N(tBu)-κ2P,P′}X2], X = Cl, Br, I, is presented. X-ray crystallography studies revealed a similar square planar PdP2X2 first coordination sphere among the three complexes. The catalytic reactivity of these complexes was tested in the Suzuki-Miyaura coupling reaction, showing that the X = Cl, Br, complexes are more active than the X = I analogue. The differences in the catalytic reactivity within this series of complexes, as well as comparisons with similar palladium(II) catalysts reported in the literature, are discussed with respect to the different electronegativity of the three halogens and the strong +I inductive effect of the ligand's tBu group.
- Ioannou, Polydoros-Chrysovalantis,Arbez-Gindre, Cécile,Zoumpanioti, Maria,Raptopoulou, Catherine P.,Psycharis, Vassilis,Kostas, Ioannis D.,Kyritsis, Panayotis
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- Rapid Suzuki-Miyaura cross-coupling reaction catalyzed by zirconium carboxyphosphonate supported mixed valent Pd(0)/Pd(II) catalyst
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Mixed valent Pd(0)/Pd(II) nano-sized aggregates supported onto a chemically robust layered zirconium carboxyphosphonate framework is prepared and its catalytic activity in Suzuki-Miyaura cross coupling reaction is explored. The exceptionally high catalytic efficacy of the heterogeneous catalyst in Suzuki-Miyaura cross coupling reaction is signified by remarkably short reaction time 2?minutes and high turnover frequency of 1.3 x 104?hr?1. The catalyst can be recycled several times without significant loss of catalytic efficacy, while spectroscopic, structural and microscopic investigations suggest the integrity of the catalyst even after fifth catalytic cycle. The unique ability of the zirconium carboxyphosphonate framework to interact strongly with palladium in dual Pd(0)/Pd(II) oxidation states has been attributed to this remarkable augmentation of catalytic efficacy.
- Bhattacharyya, Bagmita,Biswas, Jyoti Prasad,Mishra, Shashank,Gogoi, Nayanmoni
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- Nickel-Catalyzed Kumada Coupling of Boc-Activated Aromatic Amines via Nondirected Selective Aryl C-N Bond Cleavage
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A nickel-catalyzed Kumada coupling of aniline derivatives was developed by selective cleavage of aryl C-N bonds under mild reaction conditions. Without preinstallation of an ortho directing group on anilines, the cross-coupling reactions of Boc-protected aromatic amines with aryl Grignard reagents afforded unsymmetric biaryls. Mechanistic studies by DFT calculations revealed that the nickel-mediated C-N bond cleavage is the rate-limiting step.
- Zhang, Zheng-Bing,Ji, Chong-Lei,Yang, Ce,Chen, Jie,Hong, Xin,Xia, Ji-Bao
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p. 1226 - 1231
(2019/02/14)
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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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