612-94-2Relevant academic research and scientific papers
Synthesis and catalytic activity in suzuki coupling of nickel complexes bearing n -butyl- and triethoxysilylpropyl-substituted NHC ligands: Toward the heterogenization of molecular catalysts
Oertel, Anna Magdalena,Ritleng, Vincent,Chetcuti, Michael J.
, p. 2829 - 2840 (2012)
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.
Covalently stabilized Pd clusters in microporous polyphenylene: An efficient catalyst for Suzuki reactions under aerobic conditions
Song, Qi,Jia, Yuying,Luo, Bin,He, Haiyong,Zhi, Linjie
, p. 2460 - 2465 (2013)
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
Porphyrenediynes: synthesis and cyclization of meso-enediynylporphyrins
Spence, John D.,Hargrove, Amanda E.,Crampton, Hannah L.,Thomas, David W.
, p. 725 - 728 (2007)
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.
Construction of covalent organic framework for catalysis: Pd/COF-LZU1 in Suzuki-Miyaura coupling reaction
Ding, San-Yuan,Gao, Jia,Wang, Qiong,Zhang, Yuan,Song, Wei-Guo,Su, Cheng-Yong,Wang, Wei
, p. 19816 - 19822 (2011)
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.
'Awaken' aryl sulfonyl fluoride: a new partner in the Suzuki-Miyaura coupling reaction
Ding, Chengrong,Guan, Chenfei,Miao, Huihui,Zhang, Guofu,Zhao, Yiyong
supporting information, p. 3560 - 3564 (2022/03/07)
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
Nickel-Catalyzed Direct Cross-Coupling of Aryl Sulfonium Salt with Aryl Bromide
Ma, Na-Na,Ren, Jing-Ao,Liu, Xiang,Chu, Xue-Qiang,Rao, Weidong,Shen, Zhi-Liang
supporting information, p. 1953 - 1957 (2022/03/27)
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.
Synthesis of ultrafine AuPd bimetallic nanoparticles using a magnetite-cored poly(propyleneimine) dendrimer template and its sustainable catalysis of the Suzuki coupling reaction
Lakshmi, Kannappan,Rangasamy, Rajmohan,Selvaraj, Mari
, p. 14227 - 14235 (2021/08/16)
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.
Impact of Solvent and Their Contaminants on Pd/C Catalyzed Suzuki-Miyaura Cross-Coupling Reactions
de Lambert de Boisjan, Alexandre,Allemann, Christophe,Fadini, Luca
, (2021/05/17)
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.
Evaluation of P-bridged biaryl phosphine ligands in palladium-catalysed Suzuki-Miyaura cross-coupling reactions
Holzapfel, Cedric W.,Lamola, Jairus L.,Maumela, Munaka Christopher,Moshapo, Paseka T.
, p. 26883 - 26891 (2021/08/17)
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.
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?
De Tovar, Jonathan,Rataboul, Franck,Djakovitch, Laurent
, p. 133 - 147 (2021/05/10)
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.
