- Polymeric 2,2′-biquinolyl-containing NiII complexes as catalysts for the Suzuki reaction
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The Suzuki reaction with polymeric Ni catalysts based on the biquinolyl-containing polyamic acids can be carried out under conditions close to the conditions used for the catalytic transformations in the presence of PdII complexes with the same polymeric ligands. However, the yields of the cross-coupling products on the Ni catalysts are somewhat lower than those obtained in the presence of palladium complexes. The yield of the cross-coupling product increases with the increase in the conformational mobility of the polymeric ligand. Unlike catalysis by palladium complexes, in catalytic transformations by nickel complexes activation of the catalyst is required. Such an activation can be carried out either by addition of chemical reducing agents or by applying the corresponding cathodic potential (-0.8 V relative to Ag/AgCl/KCl). The electrochemical activation was shown to lead to higher yields of the cross-coupling product than the use of chemical reducing agents.
- Magdesieva,Nikitin,Polyakova,Yakimansky,Goikhman,Podeshvo
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- Mercaptoaryl-Oxazoline Complexes of Palladium and Their High Activities as Catalysts for Suzuki–Miyaura Coupling Reactions in Water
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The synthesis, spectroscopic characterization, and catalytic activities of a series of PdII complexes bearing the monoanionic, bidentate ligand 2-(2-thiophenyl)-4,4-dimethyloxazoline (S-Phoz) are reported. These complexes were used as precatalysts for Suzuki–Miyaura coupling reactions under aqueous conditions. The dimers [{PdX(S-Phoz)}2] (X = Cl, Br, I; 1–3) were treated with the N-heterocyclic carbene (NHC) ligand 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) to afford the mononuclear complexes [PdX(S-Phoz)(IMes)] (X = Cl, Br, I; 4–6). The σ-donor/π-acceptor complexes [PdCl(S-Phoz)(EPh3)] (E = P, As, Sb; 7–9) were synthesized to evaluate the influence of a second donor ligand on the catalytic activity. Within the [PdCl(S-Phoz)L] series, the activity trend for L follows the trend PPh3 > IMes ≈ AsPh3 > SbPh3. The sulfur-bridged dinuclear complexes 1–3 are highly active for the benchmark coupling of p-bromoacetophenone with phenylboronic acid and exhibit turnover frequencies (TOFs) of up to 16000 h–1. DFT and G0W0 calculations were performed to rationalize the facile reduction and, hence, excellent activities of the dinuclear complexes.
- Holzer, Christof,Dupé, Antoine,Peschel, Lydia M.,Belaj, Ferdinand,M?sch-Zanetti, Nadia C.
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- Pd-Co3[Co(CN)6]2 hybrid nanoparticles: Preparation, characterization, and challenge for the Suzuki-Miyaura coupling of aryl chlorides under mild conditions
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Because of their abundance and low cost, organo chlorides are the most desirable substrates from the industrial point of view in Suzuki-Miyaura cross-coupling reactions. However, catalytic application of Pd nanoparticles (NPs) for Suzuki coupling of aryl chlorides is still a challenge. Here, we design a novel catalyst by combining Pd NPs with Co3[Co(CN)6]2 nanocrystals for Suzuki-Miyaura coupling of aryl chlorides. This nanocatalyst demonstrated good activity (yield 86.2% at 80 °C), high TOF, great stability, easy separation, excellent reusability (initial rates were not reduced after five cycles) and low cost in Suzuki reactions.
- Li, Ren,Li, Ran,Wang, Changlai,Gao, Lei,Chen, Qianwang
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- Suzuki-Miyaura coupling reactions using novel metal oxide supported ionic palladium catalysts
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Palladium substituted CeO2, SnO2 and their mixed oxides have been synthesized in quantitative yields out of non-toxic and inexpensive precursors using a simple and rapid single step solution combustion method. The resulting oxides, especially the mixed oxides Ce0.79Sn0.20Pd0.01O2-δ, Sn0.79Ce0.20Pd0.01O2-δ and Sn0.99Pd0.01O2-δ proved to be highly active (TOF > 12,000 h?1) for Suzuki-Miyaura cross-couplings of phenylboronic acid with various bromoarenes. The reactions were carried out in ambient air at moderate temperatures using environmentally friendly aqueous ethanol solutions as reaction solvents. Minimal amounts of palladium in the product solution ( 0.14 mg/L), the reaction kinetics as well as catalyst poisoning tests support the thesis that the reaction proceeds via dissolved palladium species in a homogeneous reaction mechanism. Nevertheless, the synthesized catalysts could be reused for at least five times with only minor changes in activity and no changes in the crystal structure, indicating the high potential of the investigated catalysts as quasi-heterogeneous C[sbnd]C coupling catalysts.
- Lichtenegger,Maier,Hackl,Khinast,G?ssler,Griesser,Kumar, V.S. Phani,Gruber-Woelfler,Deshpande
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- C-Br activation of aryl bromides at Ni0(NHC)2: Stoichiometric reactions, catalytic application in Suzuki-Miyaura cross-coupling, and catalyst degradation
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Complex [Ni2(iPr2Im)4(COD)] (1) (iPr2Im = 1,3-diisopropylimidazolin-2-ylidene) is a very efficient catalyst for the Suzuki-Miyaura cross-coupling reaction of 4-bromotoluene with phenylboronic acid and also mediates the Ullmann-type homo-cross-coupling reaction of bromobenzene with a moderate efficiency. Stoichiometric reactions of complex 1 with aryl bromides (ArBr) at room temperature lead to mixtures of aryl bromo complexes of the type trans-[Ni( iPr2Im)2(Br)(Ar)] and the bis(bromo) complex trans-[Ni(iPr2Im)2(Br)2] 2. The complexes trans-[Ni(iPr2Im)2(Br)(Ar)] (for Ar = Ph 3, 4-MeC6H44, 4-Me(O)CC6H45, 4-MeOC6H46, 4-MeSC6H47, 4-Me 2NC6H48, 2-C5NH49) can be selectively synthesized by working at low temperatures and using a high dilution of the starting materials. A major deactivation pathway for trans-[Ni(iPr2Im)2(Br)(Ar)] was identified in the presence of aryl bromides. This deactivation process includes (i) the formation of trans-[Ni(iPr2Im)2(Br) 2] from trans-[Ni(iPr2Im)2(Br)(Ar)] (2) and ArBr and (ii) the formation of an imidazolium salt of the type 2[ iPr2Im-Ar]+[NiBr4]2- from trans-[Ni(iPr2Im)2(Br)2] (2) and ArBr. The reactions of complex 2 with a series of aryl halides at higher temperatures lead to the decomposition of the bis(carbene) nickel moiety with formation of the imidazolium salts 2[iPr2Im-Ar] +[NiBr2X2]2- (for X = I, Ar = Ph 10 and X = Br, Ar = Ph 11, 4-MeC6H412, 4-FC6H 413, 4-OSi(CH3)3-C6H414) in high yields.
- Zell, Thomas,Fischer, Peter,Schmidt, David,Radius, Udo
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- An efficient and reusable catalyst for Suzuki cross-coupling reactions in aqueous solution - Hollow palladium-ferrum bimetallic magnetic spheres
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Hollow Pd-Fe bimetallic magnetic spheres are synthesized in this work. Such materials are successfully characterized by ICP-AES, XPS, TEM, BET, XRD, and VSM, etc. These as-prepared hollow materials have high catalytic activity during Suzuki cross-coupling reactions between aryl halides and arylboronic acids in water. Meanwhile, the catalytic activity can be adjusted via changing the composition of the catalyst. The enhanced activity was attributed to both the hollow chamber structure and the promotional effect of Fe-dopants, which provided more Pd active sites during the reaction. Besides, due to the incorporation of ferrum, the recycling processes of the magnetic catalyst became simpler and more efficient.
- Liu, Mengmeng,Zhu, Xiaohang,Wu, Li,Zhou, Xingchun,Li, Jing,Ma, Jiantai
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- Synthesis of brominated bisamides and their application to the suzuki coupling
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Two brominated bisamides were developed by this protocol. Compounds were synthesized either by 4-bromobenzoyl chloride and ethylenediamine or by ortho-phenylenediamine. The choice of the diamine led to the desired products, which were characterized by IR,
- Nobre, Sabrina M.,Cavalheiro, Valeria M.S.,Duarte, Leonardo S.
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- Benzimidazolyl based Schiff base palladium complex in an ionic liquid: an effective combination for Suzuki coupling
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A new benzimidazole based Pd(II) Schiff base complex was prepared and its catalytic activity was evaluated for Suzuki cross-coupling reactions in ethyl-methyl imidazolium hexafluorophosphate [EMIM PF6] ionic liquid at ambient temperature. The system provides a stable and reusable method for coupling reactions. Optimization for suitable reaction conditions were studied with respect to the effect of catalyst concentration, effects of additives, solvent and substituents on boronic acid. Good to excellent yields were achieved using a modest amount of the catalyst. The reaction time was less and the yield was more compared to previously reported results. In addition, the catalyst can be easily reused and recycled for six times without much loss in activity; this is an example of sustainable and green methodology.
- Basappa Chidananda, Vasantha Kumar,Ramakrishna, Dileep,Kaur, Manpreet,Hosakere Doddarevanna, Revanasiddappa
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- (Ni,Mg)3Si2O5(OH)4 solid-solution nanotubes supported by sub-0.06 wt % palladium as a robust high-efficiency catalyst for Suzuki-Miyaura cross-coupling reactions
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(Ni1-x,Mgx)3Si2O 5(OH)4 solid-solution nanotubes (NTs) with tunable compositions were hydrothermally synthesized by altering the molar ratio of Mg2+ to Ni2+. The as-synthesized NTs were loaded with sub-0.06 wt % palladium (Pd; ～0.045 wt %) for Suzuki-Miyaura (SM) coupling reactions between iodobenzene or 4-iodotoluene and phenylboronic acid. The (Ni,Mg)3Si2O5(OH)4 (Mg 2+:Ni2+ = 1.0:1.0) NTs supported by 0.045 wt % Pd promoted the iodobenzene-participated coupling reaction with a high yield of >99%, an excellent recycling catalytic performance during 10 cycles of catalysis with yields of ～99%, and also an extremely low Pd releasing level of ～0.02 ppm. High-activity Pd and PdO clusters, multitudes of dislocations, and defects and terraces contained within the NTs should contribute to the (Ni,Mg) 3Si2O5(OH)4 (Mg2+:Ni 2+ = 1.0:1.0) NTs supported by 0.045 wt % Pd as a robust, reusable, and high-efficiency catalyst for SM coupling reactions with an extremely low Pd releasing level. The present hydrothermally stable (Ni,Mg)3Si 2O5(OH)4 (Mg2+:Ni2+ = 1.0:1.0) solid-solution silicate NTs provided an ideal alternative tubular-structured support for noble- or transition-metal catalysts with low Pd loading, good recycling, and extremely low ppb levels of Pd release, which could also be extended to some other SM coupling reactions.
- Zhu, Wancheng,Yang, Yan,Hu, Shi,Xiang, Guolei,Xu, Biao,Zhuang, Jing,Wang, Xun
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- Core-shell structured magnetic mesoporous silica supported Schiff-base/Pd: An efficacious and reusable nanocatalyst
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In this research, a novel Schiff-base/palladium complex containing magnetic ordered mesoporous silica (Fe3O4@MCM-41-SB/Pd) material with a core-shell structure is prepared and characterized, and its catalytic application is developed. The Fe3O4@MCM-41-SB/Pd nanocatalyst was characterized using FT-IR, TGA, SEM, VSM, PXRD and energy-dispersive X-ray (EDX) spectroscopy. This nanocatalyst showed high performance in the Suzuki cross-coupling reaction under ultrasonic conditions and delivered the corresponding products in high to excellent yield. The recovery study of the nanocatalyst proved that its activity is maintained during several stages of reuse. Moreover, the high stability of palladium species on the core-shell surface was confirmed by leaching and poisoning tests.
- Shaker, Masoumeh,Elhamifar, Dawood
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- Pd-catalyzed Kumada-Corriu cross-coupling reactions at low temperatures allow the use of Knochel-type Grignard reagents
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A catalyst system able to operate at temperatures as low as -65 °C for the Pd-catalyzed Kumada-Corriu cross-coupling reaction is described. This unprecedented level of activity allows the use of highly functionalized (Knochel-type) Grignard reagents. Additionally, the tolerance of the protocol toward a wide variety of functional groups allows for the synthesis of valuable compounds, including heterocyclic or polyfluoro biaryls. Copyright
- Martin, Ruben,Buchwald, Stephen L.
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- Synthesis of carbon nanotube supported Pd catalysts and evaluation of their catalytic properties for C{single bond}C bond forming reactions
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A simple method of depositing Pd nanoparticles onto carbon nanotubes (CNTs) as catalyst supports is devised for C{single bond}C bond forming reactions. Thiol groups were utilized as linkers to secure the Pd nanoparticles without agglomeration. The samples were characterized by TEM, XPS and Raman spectroscopy. The prepared CNT-Pd nanocomposites effectively promoted the formation of C{single bond}C bonds at a low Pd content (～2.0%) and in the absence of any ligand. This result indicates that surface thiolation is an effective way to obtain highly dispersed metal nanoparticles on the surface of CNTs and markedly improves their catalytic activity.
- Kim, Ja Young,Jo, Youngshin,Kook, Seong-Keun,Lee, Sunwoo,Choi, Hyun Chul
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- Suzuki cross-coupling reaction of aryl halides with arylboronic acids catalysed by Pd(II)-NaY zeolite
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Pd(II)-exchanged NaY zeolite showed high activity in the Suzuki cross-coupling reactions of aryl bromides and iodides without added ligands. The DMF:water ratio, and the type and amount of base were found to be critical for the efficiency of the reaction. The catalyst is reusable after regeneration.
- Bulut, Hatice,Artok, Levent,Yilmazu, Selahattin
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- A periodic mesoporous organosilica containing a carbapalladacycle complex as heterogeneous catalyst for Suzuki cross-coupling
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A series of periodic mesoporous organosilica with varying contents of a carbapalladacycle complex forming part of the walls of the hybrid material has been prepared. These solids have a very large surface area (ca. 1000 m 2 g-1), a mononodal pore size distribution (ca. 3 nm), and a periodic hexagonal structure typical for MCM-41 materials. The fresh solids exhibit high activity for the Suzuki cross-coupling of phenylboronic acid with bromobenzoic acid and bromoacetophenone. The initial catalytic activity of these PMO materials is significantly higher than that of a related amorphous silica catalyst containing the same complex. Leaching studies, either filtering the solid in hot solution or three-phase-test attaching one of the reagents to a solid, demonstrate that there is a contribution to the catalysis of leached species from the solid into the solution. The solid can be reused although a progressive deactivation caused by complex degradation, and mesopore collapse has been observed.
- Corma, Avelino,Das, Debashis,Garcia, Hermenegildo,Leyva, Antonio
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- Synthesis of Pd nanocrystals in phosphonium ionic liquids without any external reducing agents
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Trihexyl(tetradecyl)phosphonium ionic liquids (ILs) are found to support the formation of Pd(0) nanoparticles without the addition of reducing agents such as NaBH4. The resulting particles are highly crystalline and have been characterized by a range of techniques including TEM and XRD. Their sizes are in the range 7 ± 2 nm. The particle formation process is highly dependent on the anion of the IL with no nanoparticles observed when the chloride derivative was used. Particle shape could be controlled through varying the anion of the IL and the Pd(ii) precursor used. Palladium chloride reagents gave truncated octahedron shaped particles in trihexyl(tetradecyl)phosphonium dodecylbenzenesulfonate, whereas palladium acetate under the same conditions afforded a mixture of shapes including triangular plates. We propose that the presence of chloride anions in the reaction mixtures led to oxidative etching of the particles and that this process can be reduced in the presence of certain anion partners in the IL including bis(2,4,4-trimethylpentyl)phosphinate. Two possible reduction mechanisms based on reactions of the phosphonium cation are suggested for the formation of the Pd(0) species. The resulting nanoparticles are effective in catalyzing the Suzuki reaction of 4-bromotoluene and benzene boronic acid. The Royal Society of Chemistry.
- Kalviri, Hassan A.,Kerton, Francesca M.
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- Detailed Mechanism for Hiyama Coupling Reaction in Water Catalyzed by Linear Polystyrene-Stabilized PdO Nanoparticles
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The catalytic cycle of the Hiyama coupling reaction in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PS-PdONPs) was investigated. The formation of 4-methylbiphenyl was confirmed from the reaction of 4-bromotoluene with the catalyst recovered from the reaction of PS-PdONPs with trimethoxyphenylsilane. The catalytic activity of PS-PdONPs significantly diminished upon addition of NaI or poly(4-vinylpyridine). The Hiyama coupling reaction using PS-PdONPs as a catalyst proceeds through a different mechanism from the commonly accepted one that starts from the oxidative addition of an aryl halide to a Pd(0) species.
- Sakon, Akira,Ii, Ryoma,Hamasaka, Go,Uozumi, Yasuhiro,Shinagawa, Tsutomu,Shimomura, Osamu,Nomura, Ry?ki,Ohtaka, Atsushi
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- Palladium Nanoparticles Anchored on Thiol Functionalized Xylose Hydrochar Microspheres: An Efficient Heterogeneous Catalyst for Suzuki Cross-Coupling Reactions
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Abstract: Novel thiol functionalized xylose hydrochar microspheres supported palladium nanoparticles (C–SH–Pd) were synthesized by gentle heating of palladium (II) acetate and thiol functionalized xylose hydrochar (C–SH) in ethanol. The as-prepared C–SH–Pd exhibited high catalytic activity towards Suzuki reactions with a yield of high up to 100%. Moreover, it could be reused for at least five times without heavily loss of the catalytic activity. The amount of palladium entrapped on C-SH microspheres was measured by AAS and found to be 1.42?mmol/g. Leaching studies showed that the filtrate contained less than 0.2?ppm Pd. Due to the superior catalytic performance and stability of the C–SH–Pd catalyst, it can be exploited in other cross coupling reactions in the long run. Graphic Abstract: [Figure not available: see fulltext.].
- Huang, Pingquan,Zeng, Xiaoyan,Du, Fan,Zhang, Lei,Peng, Xinwen
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- La-Metal-Organic Framework incorporating Fe3O4 nanoparticles, post-synthetically modified with Schiff base and Pd. A highly active, magnetically recoverable, recyclable catalyst for C–C cross-couplings at low Pd loadings
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Unprecedented post-synthetic modification (PSM) applied on a new La-MOF containing Fe3O4 nanoparticles (NPs), via Schiff base build-up (with pyridine-2-carboxaldehyde) and PdCl2 coordination, proved to be an advantageous strategy to produce a superior heterogeneous catalyst for Suzuki-Miyaura C–C bond formation. The Fe3O4@La-MOF-Schiff base-Pd ensemble (characterized by PXRD, EDS, TEM, HAADF-STEM, VSM, TGA) showed very active, quite stable, magnetically recoverable and reusable in coupling of bromo- or iodoaryls with arylboronic acids, affording practically quantitative yields of biaryls (>99%) and high TONs and TOFs. The catalyst has been recycled up to 12 times without significant loss of the catalytic activity. A synergistic cooperativity between Pd and the oxophilic La nodes, through the organic linker, is responsible for enhancing the catalyst activity and stability.
- Xiong, Gang,Chen, Xiao-Ling,You, Li-Xin,Ren, Bao-Yi,Ding, Fu,Dragutan, Ileana,Dragutan, Valerian,Sun, Ya-Guang
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- Phosphine oxide polymer for water-soluble nanoparticles
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A phosphine oxide polymer was developed using bis(dichlorophosphino)ethane and poly(ethylene glycol). This polymer system was used to transfer various nanoparticles from organic solvents to water, retaining their physical properties and reactivities. Copyright
- Kim, Sang-Wook,Kim, Sungjee,Tracy, Joseph B.,Jasanoff, Alan,Bawendi, Moungi G.
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- Novel triazole-modified chitosan@nickel nanoparticles: efficient and recoverable catalysts for Suzuki reaction
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We have developed an efficient strategy to prepare uniformly sized spherical NiNPs supported on chitosan surface via click chemistry. This heterogeneous catalyst has demonstrated promising catalytic activity for the Suzuki-Miyaura coupling. Furthermore, the obtained catalyst can be easily separated from the reaction mixture by centrifugation and reused several times with no significant loss of activity.
- Hajipour, Abdol R.,Abolfathi, Parisa
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- Palladium(0) nanoparticles encapsulated in diamine-modified glycidyl methacrylate polymer (GMA-CHDA) applied as catalyst of Suzuki-Miyaura cross-coupling reaction
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Cyclohexyldiamine-modified glycidyl methacrylate polymer (GMA-CHDA) in the form of gel-type beads was used to encapsulate Pd(0) nanoparticles 4-15 nm in diameter and applied as a new, reusable catalyst for the Suzuki-Miyaura cross-coupling reaction of 2- and 4-bromotoluene with phenylboronic acid. It was found that the precatalyst preparation methodology strongly influenced its catalytic activity. The best results (100% yield of the product) were obtained when GMA-CHDA was first treated with hydrazine (reducing agent for Pd(ii)) and next with PdCl2 solution. The new catalyst acts heterogeneously, and the post-reaction solution after catalyst separation is not catalytically active, suggesting that there is no leaching. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
- Trzeciak, Anna M.,Mieczynska, Ewa,Ziolkowski, Jozef J.,Bukowski, Wiktor,Bukowska, Agnieszka,Noworol, Jaroslaw,Okal, Janina
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- Efficient batch and continuous flow Suzuki cross-coupling reactions under mild conditions, catalysed by polyurea-encapsulated palladium (II) acetate and tetra-n-butylammonium salts
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Suzuki cross-coupling reactions are effected in both conventional organic solvents, under continuous flow conditions at 70 °C, and in batch mode in supercritical carbon dioxide (scCO2), at temperatures as low as 40 °C in the presence of palladium(II) acetate microencapsulated in polyurea [PdEnCat] and tetra-n-butylammonium salts. The Royal Society of Chemistry 2005.
- Lee, Connie K. Y.,Holmes, Andrew B.,Ley, Steven V.,McConvey, Ian F.,Al-Duri, Bushra,Leeke, Gary A.,Santos, Regina C. D.,Seville, Jonathan P. K.
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- Microwave-assisted synthesis of Pd nanoparticles and their catalysis application for Suzuki cross-coupling reactions
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Pd nanoparticles (PdNPs) were prepared via microwave-assisted chemical reduction method (PdNPs-MW) and a conventional chemical reduction method (PdNPs-C) using ethanol as the reducing agent in the presence of polyvinylpyrrolidone (PVP), respectively. The as-prepared PdNPs were characterized by UV–vis spectroscopy, TEM, XRD, and X-ray photoelectron spectroscopy analysis. The results showed that PdNPs- MW had a uniform structure and narrower size distribution with diameters of 3.6–5.4 nm. An obvious increase in size of the PdNPs was apparent for PdNPs-C. The PdNPs-MW demonstrated 68.7% yield toward the Suzuki cross-coupling reaction of 4-bromobenzonitrile and phenylboronic acid for 10 min with a higher turnover frequency of 41220 h-1 compared with the value of PdNPs-C (20580 h-1).
- Zhang, Jian,Bai, Xuefeng
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- Glucopyranoside-Functionalized NHCs-Pd(II)-PEPPSI Complexes: Anomeric Isomerism Controlled and Catalytic Activity in Aqueous Suzuki Reaction
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The first system controlled anomeric isomerism of glucopyranoside-functionalized N-heterocyclic carbenes based pyridine enhanced precatalyst preparation, stabilization and initiation type palladium(II) complexes (Glu-NHCs-Pd(II)-PEPPSI, 2a–d) were prepare
- Zhou, Zhonggao,Xie, Qian,Li, Jing,Yuan, Yangyang,Liu, Yong,Liu, Yulong,Lu, Dongliang,Xie, Yongrong
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- Arrested catalysis: Controlling Kumada coupling activity via a redox-active N-heterocyclic carbene
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Optimized syntheses for 1,3-dimesitylnaphthoquinimidazolium chloride [1H][Cl] and the corresponding silver-NHC complex [AgCl(1)] (2) were developed, enabling access to this versatile reagent in near-quantitative yield. Transmetalation from 2 to [NiCl2(PPh3)2], trans-[PdCl2(PhCN)2], or trans-[PtCl2(PhCN) 2] afforded the Group 10 complexes trans-[MCl2(1) 2] (3a-c, M) Ni, Pd, and Pt, respectively) in excellent overall yield (>95%) after three steps from commercially available starting materials. Electrochemical measurements indicated that the E1/2 and ΔE1/2 values for the quinone reduction couples were independent of the identity of the bridging transition metal in these complexes. Whereas attempts to isolate the reduced complexes were unsuccessful, UV/vis spectroelectrochemical analysis confirmed that electrochemical reduction of 3a-c in situ afforded optical difference spectra consistent with the formation of the expected reduced species. Complex 3a was found to catalyze the Kumada cross-coupling reaction between PhMgCl and a range of bromoarenes at room temperature. Addition of 2 equiv of cobaltocene (with respect to 3a) to the coupling reaction with bromotoluene caused a decrease in catalytic activity (from 4.7 × 10-5 to 2.7 × 10-6 s -1), which was attributed to the conversion of 3a to an arrested state. Subsequent introduction of ferrocenium tetrafluoroborate (2 equiv with respect to 3a) restored a significant degree of catalytic activity (k obs) 1.2 × 10-5 s-1). Redox-switching experiments performed over different time scales Revealed that the catalyst was stable in the reduced/inactive state and that extended durations in this state did not impede catalytic reactivation upon subsequent oxidation.
- Tennyson, Andrew G.,Lynch, Vincent M.,Bielawski, Christopher W.
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- Fluoride-free Hiyama coupling by palladium abnormal N-heterocyclic carbene complexes
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A series of palladium complexes of the abnormal N-heterocyclic carbene ligands of the type (a-NHC)PdI2(L) [L = NC5H5(1-3)b and PPh3(1-3)c] effectively catalyzed the Hiyama coupling of aryl bromides and iodides with PhSi(OMe)3 under the highly desired fluoride-free conditions. Interestingly enough, the pyridine based trans-(1-3)b complexes and a PPh3 derived cis-3c complex exhibited higher yields than the related PPh3 derived trans-(1-2)c complexes. The superior performances of the pyridine based trans-(1-3)b complexes and the PPh3 derived cis-3c complex have been correlated to a tighter binding of the a-NHC ligand to the palladium center in these complexes, leading to a greater (a-NHC) ligand influence on the metal center partaking in the catalysis.
- Modak, Sudipta,Gangwar, Manoj Kumar,Nageswar Rao, Mitta,Madasu, Mahesh,Kalita, Alok Ch.,Dorcet, Vincent,Shejale, Mayuri Arun,Butcher, Ray J.,Ghosh, Prasenjit
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- Effect of 2-substituents on allyl-supported precatalysts for the Suzuki-Miyaura reaction: Relating catalytic efficiency to the stability of palladium(I) bridging allyl dimers
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One of the most commonly used classes of precatalysts for cross-coupling are Pd(II) complexes of the type (η3-allyl)Pd(L)Cl. Here, we report the first full investigation of how the steric and electronic properties of the 2-substituent affect th
- Hruszkewycz, Damian P.,Guard, Louise M.,Balcells, David,Feldman, Nicola,Hazari, Nilay,Tilset, Mats
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- Electronic effects of ligands on the cobalt(II)-porphyrin-catalyzed direct C-H arylation of benzene
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The electronic effects of the porphyrin ligand on the cobalt(II)-porphyrin- catalyzed direct C-H arylation of benzene with 4-iodotoluene were explored. The investigation was facilitated by the easy preparation of various substituted porphyrin ligands. The reaction rates were found to be dependent on the electron richness of the cobalt(II)-porphyrins. Such effects are consistent with the electronic influences on the rate-determining aryl iodide bond cleavage. Copyright
- Chan, Tek Long,To, Ching Tat,Liao, Bei-Sih,Liu, Shiuh-Tzung,Chan, Kin Shing
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- Polystyrene-cross-linking Ortho-substituted triphenylphosphines: Synthesis, coordination properties, and application to Pd-catalyzed cross-coupling of aryl chlorides
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Polystyrene-cross-linking triphenylphosphines having methyl groups as ortho substituents were synthesized. Coordination of the polymer-bound tri(o-tolyl)phosphine-type ligand toward a Pd(II) complex was investigated by 31PCP/MASNMR spectroscopi
- Iwai, Tomohiro,Asano, Kiichi,Harada, Tomoya,Sawamura, Masaya
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- A Simple Synthetic Route to Well-Defined [Pd(NHC)Cl(1-tBu-indenyl)] Pre-catalysts for Cross-Coupling Reactions
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The development of robust, more efficient, general, easily accessible Pd(II)–NHC pre-catalysts remains a key issue in cross-coupling applications. A selection of well-defined, air and moisture stable [Pd(NHC)Cl(1-tBu-indenyl)] (NHC=IPr, IPrCl, IMes, SIMes, IPr*) pre-catalysts have been synthesized in good to excellent yields by reacting [Pd(1-tBu-indenyl)(μ-Cl)]2 and various NHC?HCl precursors in the presence of the weak base K2CO3 in green acetone. The synthesized Pd(II)-NHC derivatives displayed excellent catalytic activity in classical Suzuki-Miyaura and Buchwald–Hartwig reactions, especially when IPrCl is employed as ancillary ligand. Additionally, in the challenging Suzuki-Miyaura reaction between esters and arylboronic acids, the [Pd(IPr*)Cl(1-tBu-indenyl)] complex exhibited the optimum catalytic activity under very mild reaction conditions.
- Liu, Yaxu,Scattolin, Thomas,Gobbo, Alberto,Beli?, Marek,Van Hecke, Kristof,Nolan, Steven P.,Cazin, Catherine S. J.
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- One-Step Access to Heteroatom-Functionalized Imidazol(in)ium Salts
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Imidazolium salts have ubiquitous applications in energy research, catalysis, materials and medicinal sciences. Here, we report a new strategy for the synthesis of diverse heteroatom-functionalized imidazolium and imidazolinium salts from easily available 1,4-diaza-1,3-butadienes in one step. The strategy relies on a discovered family of unprecedented nucleophilic addition/cyclization reactions with trialkyl orthoformates and heteroatomic nucleophiles. To probe general areas of application, synthesized N-heterocyclic carbene (NHC) precursors were feasible for direct metallation to give functionalized M/carbene complexes (M=Pd, Ni, Cu, Ag, Au), which were isolated in individual form. The utility of the chloromethyl function for the postmodification of the synthesized salts and Pd/carbene complexes was demonstrated. The obtained complexes and imidazolium salts demonstrated good activities in Pd- or Ni-catalyzed model cross-coupling and C?H activation reactions.
- Pasyukov, Dmitry V.,Shevchenko, Maxim A.,Shepelenko, Konstantin E.,Khazipov, Oleg V.,Burykina, Julia V.,Gordeev, Evgeniy G.,Minyaev, Mikhail E.,Chernyshev, Victor M.,Ananikov, Valentine P.
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supporting information
(2022/01/31)
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- Catalytic comparison of Pd-C60 complex and its non-fullerene form bearing phosphorus ylide in C–C coupling reactions
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The new fullerene-based Pd complex [(η2-C60) Pd(Y)2] (1) and its non-fullerene form [(Y)PdCl2] (2) bearing unsymmetrical phosphorus ylide [Ph2P(CH2)2PPh2 = C(H)C(O)Cs
- Fatahi, Somayeh,Javad Sabounchei, Seyyed,Panahimehr, Mohammad,William Gable, Robert,Yousefi, Abed
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- Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
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A uniqueN,O-bidentate ligand 6-oxo-1,6-dihydro-pyridone-2-carboxylic acid dimethylamide (L1) catalyzed direct C(sp2)-H (intra/intermolecular) arylation of unactivated arenes has been developed to expedite access to (Het)biaryl scaffolds under UV-irradiation at room temperature. The protocol tolerated diverse functional groups and substitution patterns, affording the target products in moderate to excellent yields. Mechanistic investigations were also carried out to better understand the reaction pathway. Furthermore, the synthetic applicability of this unified approach has been showcasedviathe construction of biologically relevant 4-quinolone, tricyclic lactam and sultam derivatives.
- Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
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p. 208 - 218
(2021/12/29)
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- An efficient clean and sustainable methodology for catalytic C-C coupling process over a Pd-free magnetically recoverable cobalt catalyst
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The Suzuki and Sonogashira coupling reactions are important processes in organic synthesis. However, to date, these reactions have been extensively examined using Pd-based catalysts in toxic organic solvents. Therefore, developing clean and inexpensive methodologies for these reactions remained a major challenge. Herein, by taking the advantages of thiol-ene click reaction, an easy and robust strategy for surface modification of magnetic graphene oxide with a dendrimer structure was successfully developed. Dendrimer-functionalized magnetic graphene oxide was then applied for the immobilization of Co nanoparticles. Transmission electron microscopy exhibited a homogeneous distribution of Co nanoparticles with the size of about 3 nm. The resultant nanocomposite revealed high efficiency in catalytic Suzuki and Sonogashira reactions in non-hazardous and sustainable deep eutectic solvents (DESs). The DES and catalyst were simply recycled five times with gradual slight decrease in the yield of the reactions. More importantly, the catalyst was magnetically isolated at the end of the recycling process. Overall, the utilization of DES as an environmentally friendly and recoverable reaction medium, as well as replacing the low-cost cobalt catalyst as an alternative to expensive Pd catalyst along with the facile catalyst isolation by employing an external magnetic field, make the present protocol promising from economic and green chemistry points of view for the clean C-C coupling reactions.
- Masteri-Farahani, Majid,Niakan, Mahsa
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- Carbohydrate-substituted N-heterocyclic carbenes Palladium complexes: High efficiency catalysts for aqueous Suzuki–Miyaura reaction
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Metal complexes that contain carbohydrate-substituent (Carb-) N-heterocyclic carbenes (NHCs) ligand have demonstrated great success as catalysts for organic synthesis reactions. In this study, four new Carb-NHC-Pd complexes 2a-d were prepared and their catalytic activities for Suzuki–Miyaura reaction were evaluated. The Carb-NHC-Pd complex behaved as a general surfactant which leads to the formation of a temporary oil-in-water contact interface, thereby promoting the Suzuki–Miyaura reaction. A long hydrophobic alkyl chain (–nC16H33) was remotely linked to complex 2d, in which Carb-NHCs showed high electron-donating properties, and steric bulk with 1JCH constant of 1H NMR. Complex 2d exhibited a higher catalytic activity as compared with 2a (–nC2H5), 2b (–nC4H9), and 2c (–nC8H17). A series of fluorene-cored materials with different aryl groups were synthesized with high yields (34 examples, 91–99%) under the optimized reaction conditions.
- Hu, Yunchi,Huang, Qing,Huang, Yanxia,Li, Jing,Wen, Xiaoming,Xie, Qian,Xie, Yongrong,Xu, Guohai,Zhou, Zhonggao
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supporting information
(2022/02/10)
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- New Palladium – ZrO2 Nano-Architectures from Thermal Transformation of UiO-66-NH2 for Carbonylative Suzuki and Hydrogenation Reactions
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The new nanocomposites, Pd/C/ZrO2, PdO/ZrO2, and Pd/PdO/ZrO2, were prepared by thermal conversion of Pd@UiO-66-Zr?NH2 (MOF) in nitrogen or air atmosphere. The presence of Pd nanoparticles, uniformly distributed on the ZrO2 or C/ZrO2 matrix, was evidenced by transmission electron microscopy, scanning electron microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS) methods. All pyrolysed composites retained the shape of the MOF template. They catalyze carbonylative Suzuki coupling under 1 atm CO with an efficiency significantly higher than the original Pd@UiO-66-Zr?NH2. The most active PdO/ZrO2 composite, formed benzophenone with TOF up to 1600 h?1, while by using Pd@UiO-66-Zr?NH2, much lower TOF values, 51–95 h?1, were achieved. After the reaction, PdO/ZrO2 was recovered with the same composition and catalytic activity. Very good results were also obtained in the transfer hydrogenation of benzophenones to alcohols with Pd/C/ZrO2 and PdO/ZrO2 catalysts under microwave irradiation.
- Alsalahi, Waleed,Augustyniak, Adam W.,Tylus, W?odzimierz,Trzeciak, Anna M.
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supporting information
(2021/12/22)
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- Suzuki-Miyaura Cross-Coupling Reaction with Potassium Aryltrifluoroborate in Pure Water Using Recyclable Nanoparticle Catalyst
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This paper describes the Suzuki Miyaura cross-coupling reaction of aryl bromides with potassium aryltrifluoroborates in water catalyzed by linear polystyrene-stabilized PdO nanoparticles (PSPdONPs). The reaction of aryl bromides having electron-withdrawing groups or electron-donating groups took place smoothly to give the corresponding coupling product in high yields. The catalyst recycles five times without significant loss of catalytic activity although a little bit increase in size of PdNPs was observed after the reaction.
- Kawase, Misa,Matsuoka, Kyosuke,Shinagawa, Tsutomu,Hamasaka, Go,Uozumi, Yasuhiro,Shimomura, Osamu,Ohtaka, Atsushi
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- Using Data Science To Guide Aryl Bromide Substrate Scope Analysis in a Ni/Photoredox-Catalyzed Cross-Coupling with Acetals as Alcohol-Derived Radical Sources
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Ni/photoredox catalysis has emerged as a powerful platform for C(sp2)–C(sp3) bond formation. While many of these methods typically employ aryl bromides as the C(sp2) coupling partner, a variety of aliphatic radical sources have been investigated. In principle, these reactions enable access to the same product scaffolds, but it can be hard to discern which method to employ because nonstandardized sets of aryl bromides are used in scope evaluation. Herein, we report a Ni/photoredox-catalyzed (deutero)methylation and alkylation of aryl halides where benzaldehyde di(alkyl) acetals serve as alcohol-derived radical sources. Reaction development, mechanistic studies, and late-stage derivatization of a biologically relevant aryl chloride, fenofibrate, are presented. Then, we describe the integration of data science techniques, including DFT featurization, dimensionality reduction, and hierarchical clustering, to delineate a diverse and succinct collection of aryl bromides that is representative of the chemical space of the substrate class. By superimposing scope examples from published Ni/photoredox methods on this same chemical space, we identify areas of sparse coverage and high versus low average yields, enabling comparisons between prior art and this new method. Additionally, we demonstrate that the systematically selected scope of aryl bromides can be used to quantify population-wide reactivity trends and reveal sources of possible functional group incompatibility with supervised machine learning.
- Doyle, Abigail G.,Gandhi, Shivaani S.,Jiang, Shutian,Kariofillis, Stavros K.,Martinez Alvarado, Jesus I.,?urański, Andrzej M.
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supporting information
p. 1045 - 1055
(2022/01/19)
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- Silk?Fibroin-Supported Palladium Catalyst for Suzuki-Miyaura and Ullmann Coupling Reactions of Aryl Chlorides
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Recently, we have reported the preparation of a silk fibroin-supported Palladium catalyst (Pd/SF) and its use in the Suzuki-Miyaura cross-coupling of aryl iodides. Since its synthetic applicability and structural features are still far from being fully ex
- Albano, Gianluigi,Farinola, Gianluca M.,Giannini, Cinzia,Musio, Roberta,Omenetto, Fiorenzo G.,Rizzo, Giorgio,Sibillano, Teresa
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- Nickel- and Palladium-Catalyzed Cross-Coupling of Stibines with Organic Halides: Site-Selective Sequential Reactions with Polyhalogenated Arenes
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Herein, we disclose a general and efficient method for the synthesis of Sb-aryl and Sb-alkyl stibines by the nickel-catalyzed cross-coupling of halostibines with organic halides. The synthesized Sb-aryl stibines couple with aryl halides to give biaryls efficiently via palladium catalysis. Sequential reactions of stibines with polyhalogenated arenes bearing active C–I/C–Br sites and inactive C–Cl sites successfully proceeded, resulting in the formation of a variety of complex molecules with good site selectivity. Drugs such as diflunisal and fenbufen, as well as a fenofibrate derivative, were synthesized on gram scales in good yields, together with the high recovery of chlorostibine. Furthermore, catalytic mechanisms are proposed based on the results of control experiments.
- Ghaderi, Arash,Kambe, Nobuaki,Le, Liyuan,Lu, Hao,Qiu, Renhua,Tang, Ting,Tong, Zhou,Wong, Wai-Yeung,Xu, Zhi,Yin, Shuang-Feng,Zeng, Dishu,Zhang, Dejiang,Zhang, Zhao
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p. 854 - 867
(2022/01/19)
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- From Esters to Ketones via a Photoredox-Assisted Reductive Acyl Cross-Coupling Strategy
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A method was developed for ketone synthesis via a photoredox-assisted reductive acyl cross-coupling (PARAC) using a nickel/photoredox dual-catalyzed cross-electrophile coupling of two different carboxylic acid esters. A variety of aryl, 1°, 2°, 3°-alkyl 2-pyridyl esters can act as acyl electrophiles while N-(acyloxy)phthalimides (NHPI esters) act as 1°, 2°, 3°-radical precursors. Our PARAC strategy provides an alternative and reliable way to synthesize various sterically congested 3°-3°, 3°-2°, and aryl-3° ketones under mild and highly unified conditions, which have been otherwise difficult to access. The combined experimental and computational studies identified a Ni0/NiI/NiIII pathway for ketone formation.
- Chen, Yukun,Li, Weirong,Luo, Yixin,Qi, Xiaotian,Xi, Xiaoxiang,Xu, Minghao,Yuan, Weiming,Zhao, Hongping,Zheng, Songlin
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supporting information
(2021/12/06)
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- Reactions of benzyltriphenylphosphonium salts under photoredox catalysis
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The development of benzyltriphenylphosphonium salts as alkyl radical precursors using photoredox catalysis is described. Depending on substituents, the benzylic radicals may couple to form C-C bonds or abstract a hydrogen atom to form C-H bonds. A natural product, brittonin A, was also synthesized using this method.
- Boldt, Andrew M.,Dickinson, Sidney I.,Ramirez, Jonathan R.,Benz-Weeden, Anna M.,Wilson, David S.,Stevenson, Susan M.
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p. 7810 - 7815
(2021/09/28)
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- Nickel-catalyzed reductive deoxygenation of diverse C-O bond-bearing functional groups
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We report a catalytic method for the direct deoxygenation of various C-O bond-containing functional groups. Using a Ni(II) pre-catalyst and silane reducing agent, alcohols, epoxides, and ethers are reduced to the corresponding alkane. Unsaturated species including aldehydes and ketones are also deoxygenated via initial formation of an intermediate silylated alcohol. The reaction is chemoselective for C(sp3)-O bonds, leaving amines, anilines, aryl ethers, alkenes, and nitrogen-containing heterocycles untouched. Applications toward catalytic deuteration, benzyl ether deprotection, and the valorization of biomass-derived feedstocks demonstrate some of the practical aspects of this methodology.
- Cook, Adam,MacLean, Haydn,St. Onge, Piers,Newman, Stephen G.
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p. 13337 - 13347
(2021/11/20)
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- Preparation of Recyclable and Versatile Porous Poly(aryl thioether)s by Reversible Pd-Catalyzed C–S/C–S Metathesis
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Porous organic materials (polymers and COFs) have shown a number of promising properties; however, the lability of their linkages often limits their robustness and can hamper downstream industrial application. Inspired by the outstanding chemical, mechanical, and thermal resistance of the 1D polymer poly(phenylene sulfide) (PPS), we have designed a new family of porous poly(aryl thioether)s, synthesized via a mild Pd-catalyzed C–S/C–S metathesis-based method, that merges the attractive features common to porous polymers and PPS in a single material. In addition, the method is highly modular, allowing to easily introduce application-oriented functionalities in the materials for a series of environmentally relevant applications including metal capture, metal sensing, and heterogeneous catalysis. Moreover, despite their extreme chemical resistance, the polymers can be easily recycled to recover the original monomers, offering an attractive perspective for their sustainable use. In a broader context, these results clearly demonstrate the untapped potential of emerging single-bond metathesis reactions in the preparation of new, recyclable materials.
- Morandi, Bill,Rivero-Crespo, Miguel A.,Toupalas, Georgios
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supporting information
p. 21331 - 21339
(2021/12/17)
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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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- Nanocellulose Supported PdNPs as in situ Formed Nano Catalyst for the Suzuki Coupling Reaction in Aqueous Media: A Green Approach and Waste to Wealth
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An effective and highly sustainable method has been developed for the Suzuki coupling reaction of aryl halides and phenylboronic acid using in situ generated nacocellulose (NC) supported palladium nanoparticles (Pd@NC NPs) as heterogeneous catalysts in water. The formation of PdNPs was observed in the absence of additional reagents, during the course of the Suzuki reaction from NC and Pd(OAc)2. In situ formed Pd@NC NPs have been systematically characterized using TEM, EDX, XRD and FT-IR techniques. The in situ generated catalyst was separated and studied for its successful reusability up to 11 cycles. The application of aqueous media, use of in situ formed catalyst, mild reaction conditions, absence of volatile organic solvents, broad substrate scope, high product isolated yields are the significant developments of this protocol. The nanocellulose used for this protocol has been generated form the waste cotton cloth and hence it is an example for the waste to wealth and sustainable approach.
- Aabaka, Sreenath Reddy,Mao, Jincheng,Lavanya, Mallu,Venkateswarlu, Katta,Huang, Zhiyu,Mao, Jinhua,Yang, Xiaojiang,Lin, Chong
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supporting information
(2021/02/21)
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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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- 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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- CNN Palladium(II) Pincer Complexes Containing N-Substituted Monoanionic and Dianionic Guanidinate Ligands: Syntheses, Structural Aspects, and Their Utility in Suzuki-Miyaura Coupling Reactions
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The reactions of guanidines [(ArNH)(ArN=)CN(H)(C(O)Py-2)] (Ar = 2-RC6H4; R = Me (1) and CF3 (2)) with Pd(OC(O)R′)2 (R′ = Me, tBu and CF3) were studied with a view aimed at understanding the influence of substituent effects upon the nature of the resulting products. The reactions of 1 with Pd(OC(O)R′)2 (R′ = Me and CF3) in toluene at 65 °C afforded [Pd{κ3(C,N,N)}(OC(O)R′)] (R′ = Me (3) and CF3 (4)), while the analogous reaction involving 1 and Pd(OC(O)tBu)2 afforded [Pd{κ3(C,N,N)}(μ-OC(O)tBu)Pd{κ3(C,N,N)}] (5). The analogous reactions of 2 with Pd(OC(O)R′)2 (R′ = Me, tBu and CF3) afforded [Pd{κ3(C,N,N)}(μ-OC(O)R′)Pd{κ3(C,N,N)}] (R′ = Me (6) and tBu (7)) and [Pd{κ3(C,N,N)}(OC(O)CF3)] (8), respectively. Complexes 5-7 were treated with 2 equiv of Lewis bases, L at RT to afford [Pd{κ3(C,N,N)}(L)] [L = PPh3(9), 4-aminopyridine (10 and 11), and MeCN (12)]. The mechanisms of formation of new complexes were proposed. Complex 3 was treated with 12 in the presence of excess of NaOC(O)tBu in CHCl3 under reflux condition to afford a mixed Pd(II) pincer, [Pd{κ3(C,N,N)}(μ-OC(O)tBu)Pd{κ3(C,N,N)}] (15), and this observation indirectly supports the mechanism proposed for the formation of 5-7. The mechanisms of formation of 9-12 were verified by in situ reaction involving 7 and PPh3 (1 and 2 equiv) through 19F NMR spectroscopy. The new compounds were fully characterized, and molecular structures of 1, 3·C7H8, 4-6, 8·C7H8, 9, and 10·H2O were determined by SCXRD. The CNN tridentate guanidinate ligands were present in monoanionic (3·C7H8, 4 and 8·C7H8), mono- and dianionic (5 and 6), and dianionic (9 and 10·H2O) forms, and hence the structures of 5 and 6 are unprecedented. Complex 3·C7H8 was used as an efficient catalyst in Suzuki-Miyaura reactions involving sterically hindered aryl bromides and aryl boronic acids.
- Sinha, Nitish Kumar,Thirupathi, Natesan
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p. 3535 - 3549
(2021/11/12)
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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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- Cooperative Ligand-Promoted P(III)-Directed Ruthenium-Catalyzed Remote Meta-C-H Alkylation of Tertiary Phosphines
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Herein, we disclose a ruthenium-catalyzed meta-selective C-H activation of phosphines by using intrinsic P(III) as a directing group. 2,2,6,6-Tetramethylheptane-3,5-dione acts as the ligand and exhibits an excellent performance in boosting the meta-alkylation. The protocol allows an efficient and straightforward synthesis of meta-alkylated tertiary phosphines. Several meta-alkylated phosphines were evaluated for Pd-catalyzed Suzuki coupling and found to be superior to commercially available ortho-substituted phosphines. The practicability of this methodology is further demonstrated by the synthesis of difunctionalized phosphines.
- Zhou, Zheng-Xin,Li, Jia-Wei,Wang, Liang-Neng,Li, Ming,Liu, Yue-Jin,Zeng, Ming-Hua
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supporting information
p. 2057 - 2062
(2021/04/05)
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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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- Heterogeneous Fe3O4@Si–NHC–Pd Catalyst: Synthesis, Characterization, and Catalytic Activity in the Suzuki–Miyaura Cross-Coupling Reaction under Mild Conditions
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Abstract: A novel Fe3O4@Si–NHC–Pd catalystwith N-heterocyclic carbenes (NHCs) moiety as an alternative ligand tophosphines for metal complexes has been synthesized and characterized by variousmethods. Synthesis of metal nanoparticles has been accomplished withoutaggregation, and the prepared catalyst has been applied in theSuzuki–Miyauracross-coupling reaction of boronic acids and aryl halides in water usingEt3N as a base. The catalyst has demonstrated highefficiency at room temperature and can be easily removed from the reaction mediausing an external magnetic field and recycled at least five times withoutsignificant decrease of its activity.
- Kalishomi, R. Ghavidel,Rostamizadeh, S.
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p. 1140 - 1146
(2021/08/06)
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- Easily Prepared Mono(N,N-dialkylamino)phosphine Palladium(II) Complexes: Structural and Catalytic Evaluation
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The search for efficient, active and universal catalyst systems for transition-metal catalyzed cross-coupling reactions, continues to be of interest to researchers world-wide. Herein, we report two new Pd(II) complexes, effortlessly prepared from N,N-dialkylamino-phosphines for Suzuki-Miyaura cross-coupling reactions. These sufficiently hindered (% VBur=30.0–31.5 %) and electron rich (vCO=1947.41–1946.29 cm?1) aminophosphines formed active catalysts for Suzuki-Miyaura coupling of aryl bromides and chlorides.
- Adeyinka, Adedapo S.,Holzapfel, Cedric W.,Lamola, Jairus L.,Maumela, Munaka C.,Mmutlane, Edwin M.,Ngodwana, Lonwabo,Shilubana, Joy C.,Vatsha, Banele
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supporting information
p. 2578 - 2582
(2021/07/06)
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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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- [Pd(4-R3Si-IPr)(allyl)Cl]/K2CO3/EtOH: A highly effective catalytic system for the Suzuki-Miyaura cross-coupling reaction
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A series of R3Si-NHC-Pd complexes 1Pd-7Pd was successfully tested as a pre-catalyst for the Suzuki-Miyaura cross-coupling reaction of aryl chlorides and arylboronic acid derivatives to form a wide range of valuable biphenyl products. Use of the readily available weakly basic potassium carbonate as a base and the highly polar protic ethanol as the reaction solvent gave the target coupling products in good-to-excellent yields. The experimental data pointed to the crucial importance of the preliminary pre-catalyst activation step [i.e., the conversion of Pd(II) to Pd(0)], which is remarkably facilitated by the electron-donating trialkylsilyl groups on the NHC ligands of 1Pd–7Pd, thereby rendering them superior compared to the commercially available IPr-Pd complexes. Computational analysis revealed the mechanism of the Pd(II)→Pd(0) activation step, demonstrating the critical role of the reaction solvent and the base in the preference of our 1Pd–7Pd pre-catalysts, for which this step is both thermodynamically and kinetically more feasible.
- Choe, Yoong-Kee,Choi, Jun-Chul,Faried, Miftah,Fukaya, Norihisa,Lee, Vladimir Ya.,Matsumoto, Kazuhiro,Mizusaki, Tomoteru,Putro, Wahyu S.,Seo, Yuto,Takagi, Yukio
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- Aerobic Cu and amine free Sonogashira and Stille couplings of aryl bromides/chlorides with a magnetically recoverable Fe3O4@SiO2 immobilized Pd(II)-thioether containing NHC
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Two value added C–C cross coupling reactions; Sonogashira and Stille couplings were achieved at milder conditions in the catalytic presence of a magnetically recoverable heterogeneous catalyst Fe3O4@SiO2@NHC^SPh-Pd(II). The catalyst was earlier reported for Suzuki-Miyaura reaction, and as an extension of its catalytic efficiency, the Stille and Sonogashira cross coupling reactions under aerobic condition has been explored in present report. The Sonogashira coupling of aryl bromides and terminal alkynes produced an excellent yield (~96% at 0.25 mol% Pd) of the desired coupling product under copper and amines free conditions. Moreover, an excellent Stille coupling of readily available and more latent aryl chlorides and trialkylstannane was obtained (yields up to 95% at 0.25 mol% Pd) in absence of toxic fluorides additives. The broad substrate scope of the catalyst for both the coupling reactions and the magnetically recoverable feature of catalyst make this reaction highly desirable for industrial applications of present heterogeneous catalysis.
- Khandaka, Himanshu,Sharma, Kamal Nayan,Joshi, Raj Kumar
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supporting information
(2021/02/20)
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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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- A new Pd(II)-supported catalyst on magnetic SBA-15 for C-C bond formation via the Heck and Hiyama cross-coupling reactions
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Magnetic mesoporous silica composite (MNP@SiO2-SBA) was obtained via embedding magnetite nanoparticles between SBA-15 channels. It was silylated with N-(3-(trimethoxysilyl)propyl)picolinamide (TMS-PCA) and then complexed with Pd(II). The obtained supported Pd(II) catalyst (MNP@SiO2-SBA-PCA) was characterized by conventional methods. The prepared magnetic catalyst showed high activity in the Heck and Hiyama reactions under optimal reaction conditions, including solvent, amount of catalyst, base, and temperature. Aryl bromides and iodides showed better results than aryl chlorides, and the catalyst exhibited noticeable stability and reused several times.
- Rahimi, Leila,Mansoori, Yagoub,Nuri, Ayat,Koohi-Zargar, Behzad,Esquivel, Dolores
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- Anchored Pd(0) Nanoparticles on Synthetic Talc for the Synthesis of Biaryls and a Precursor of Angiotensin II Inhibitors
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The palladium-catalyzed Suzuki-Miyaura cross-coupling reaction is one of the most important and efficient reactions to prepare a variety of organic compounds, including biaryls. Despite the overwhelming number of reports related to this topic, some methodological difficulties persist in terms of catalyst handling, recovery, and reuse, as well as the reaction media. This work reports the rational design of new, efficient, cost-effective, and reusable palladium catalysts supported on synthetic talc for the Suzuki-Miyaura reaction. From the results, key points were identified: both designed catalysts accelerated the reaction in EtOH and an open-flask setup, affording moderate to excellent yields within a short time (e.g., 30 min) even for deactivated aryl halides; the protocol can be applied to a great number of both cross-coupling partners, showing an excellent functional group tolerance; the catalysts can be recovered and reused without significant loss of activity. This protocol was used for the synthesis of a precursor of angiotensin II inhibitors such as valsartan, losartan, irbesartan, and telmisartan.
- Dos Santos, Beatriz F.,Da Silva, Beatriz A. L.,De Oliveira, Aline R.,Sarragiotto, Maria H.,Domingues, Nelson Luís C.
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p. 933 - 942
(2020/12/28)
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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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- Photoelectric properties of aromatic triangular tri-palladium complexes and their catalytic applications in the Suzuki-Miyaura coupling reaction
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The photoelectric properties and catalytic activities of substituted triphenylphosphine and sulfur/selenium ligand supported aromatic triangular tri-palladium complexes1-4, abbreviated as [Pd3]+, were investigated. The cyclic voltammogram of [Pd3]+in CH3CN-nBu4NPF6showed a single quasi-reversible wave which was consistent with their robust property and provided preliminary proof for their electron transfer processes in catalysis. With excitation at 267 nm, [Pd3]+exhibited strong ratiometric fluorescence at 550 and 780 nm at a temperature gradient from 77 K to 287 K. These peculiar triangular tri-palladium complexes showed excellent catalytic activities and exclusive reactivity with aryl iodides over the other halogenated aromatics in the Suzuki-Miyaura coupling reaction. The electronic and steric hindrance effects of substituents on the aryl iodides and aryl boronic acids including heteroaromatics like pyridine, pyrazine and thiophenes were explored and most substrates achieved up to 99% of yields. (2-[1,1′-Biphenyl]-2-ylbenzothiazole) which was analogous to the selective cyclooxygenase-2 (COX-2) inhibitors was also synthesized with our tri-palladium catalyst and gave good isolated yield (94%). The study of the catalytic process revealed that the mechanism of the reaction may involve the replacement of the sulphur ligand on [Pd3]+by iodine from aryl iodides, which was beneficial for the matching of C-I bond energy.
- Li, Xujun,Li, Jia,Wang, Xiaoshuang,Wu, Lingang,Wang, Yanlan,Maestri, Giovanni,Malacria, Max,Liu, Xiang
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supporting information
p. 11834 - 11842
(2021/09/06)
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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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- Polydopamine-Encapsulated Dendritic Organosilica Nanoparticles as Amphiphilic Platforms for Highly Efficient Heterogeneous Catalysis in Water
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Aqueous heterogeneous catalysis is a green, sustainable catalytic process that attracts increasing attention, but it often suffers from poor mass transfer, substrate adsorption and catalyst dispersion. Herein, we synthesized a type of amphiphilic core-shell catalysts with a hydrophilic polydopamine (PDA) shell and a hydrophobic dendritic organosilica nanoparticle (DON) core for heterogeneous catalysis in water. The hydrophilic shell allowed the catalyst dispersing well in water, and the hydrophobic core facilitated the absorption of organic reactants. The hierarchical core-shell structure facilitated rational arrangement of the location of catalytic species to match the reaction sequence. The obtained metal, enzyme and metal-enzyme amphiphilic catalysts demonstrated improved stability, selectivity and activity in aqueous reactions, including Pd-catalyzed cross-couplings (Suzuki, Liebeskind-Srogl, Heck and Sonogashira), enzymatic enantioselective reduction, chemoenzymatic cascade synthesis of chiral compounds and chemoenzymatic cascade degradation of organophosphates. The amphiphilic catalysts could be easily in situ recovered, and their high catalytic performance was sustained for five cycles.
- Gao, Jing,Guo, Na,Jiang, Yanjun,Liu, Guanhua,Liu, Pengbo,Liu, Yunting,Wang, Zihan,Zhang, Lei
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supporting information
p. 1975 - 1982
(2021/06/09)
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- Preparation of metal-immobilized methacrylate-based monolithic columns for flow-through cross-coupling reactions
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With the aim of developing efficient flow-through microreactors for high-throughput organic synthesis, in this work, microreactors were fabricated by chemically immobilizing palladium-, nickel-, iron-, and copper-based catalysts onto ligand-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) [poly(GMA-co-EDMA)] monoliths, which were prepared inside a silicosteel tubing (10 cm long with an inner diameter of 1.0 mm) and modified with several ligands including 5-amino-1,10-phenanthroline (APHEN), iminodiacetic acid (IDA), and iminodimethyl phosphonic acid (IDP). The performance of the resulting microreactors in Suzuki?Miyaura cross-coupling reactions was evaluated, finding that the poly(GMA-co-EDMA) monolith chemically modified with 5-amino-1,10-phenanthroline as a binding site for the palladium catalyst provided an excellent flow-through performance, enabling highly efficient and rapid reactions with high product yields. Moreover, this monolithic microreactor maintained its good activity and efficiency during prolonged use.
- Sabarudin, Akhmad,Shu, Shin,Yamamoto, Kazuhiro,Umemura, Tomonari
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- Hydrophilic role of deep eutectic solvents for clean synthesis of biphenyls over a magnetically separable Pd-catalyzed Suzuki-Miyaura coupling reaction
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The development of an efficient and sustainable catalytic system for the preparation of biphenyls through the Suzuki-Miyaura coupling reaction is still a great challenge to green chemistry. Encouraging the prevailing challenge, in the present work, a heterogeneous Pd catalyst was synthesized through a green method and used for the production of biphenyls in deep eutectic solvents (DESs) as green reaction media. In order to prepare the catalyst, magnetite-graphene oxide nanocomposite was modified with cellulose via the click reaction and applied as support for Pd nanoparticles. Cellulose acted as both reducing and stabilizing agent for Pd nanoparticles and eliminated the requirement of a reducing agent. The prepared catalyst was characterized by different methods such as FT-IR, EDX, EDX-mapping, XPS, SEM, TEM, XRD, VSM, and ICP-OES analyses. Catalytic properties of the obtained catalyst was explored in the coupling reaction of aryl halides with aryl boronic acids in different hydrophilic and hydrophobic DESs. The presence of cellulose with hydrophilic character on the structure of catalyst offered well dispersion of the catalyst in hydrophilic DESs, which led to enhancement of its catalytic activity. Among various hydrophilic DESs, the DES composed of dimethylammonium chloride and glycerol was verified as the most effective solvent for the preparation of biphenyls. The catalyst was compatible with a variety of substrates, with which all the Suzuki coupling products were achieved in high to excellent yields. Thanks to the low solubility of catalyst and DES in organic solvents, the separated aqueous phase containing both of the catalyst and DES could be readily recovered by evaporating water and reused up to five successive runs with a stable activity. This simple and new separation strategy provided a clean and highly efficient synthetic methodology for the synthesis of various biphenyls. Moreover, hot filtration test efficiently confirmed that the catalyst is heterogeneous and completely stable under reaction conditions.
- Karimi, Sabah,Masteri-Farahani, Majid,Niakan, Mahsa,Shekaari, Hemayat
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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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- A highly controllable, effective, and recyclable magnetic-nanoparticle-supported palladium catalyst for the Suzuki–Miyaura cross-coupling reaction
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In this work, a highly efficient palladium catalyst was facilely immobilized on the surfaces of magnetic nanoparticles with the coordination of N-heterocyclic carbene. The prepared Pd–NHC@NCPs were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and inductively coupled plasma atomic emission spectrometry. With suitably designed emulsion polymerization and immobilization, the final palladium loading could reach 0.78 mmol/g. The catalyst showed outstanding catalytic performance in the Suzuki–Miyaura cross-coupling reaction among various substrates, with little catalyst usage (0.03 mol.%), short reaction time, and mild reaction conditions. In addition, the catalyst could be separated conveniently from the reacting system with an external magnet and show good catalytic performance even after being reused five times or more, indicating good recyclability.
- Ye, Lu,Liu, Xiaojing,Lu, Yangcheng
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- Suzuki-Miyaura Csp2-Csp2Cross-Couplings Employing Nickel(II) Pincer Precatalysts: Mechanistic Investigations
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This study investigates the mechanism of Suzuki-Miyaura Csp2-Csp2cross-couplings facilitated by PCP-type nickel(II) pincer complexes. By employing a combination of standard experimental and theoretical methods, it is proposed that a nickel(I)/(III) cycle is involved in this reaction and single-electron pathways likely operate in this transformation.
- Ho, Curtis C.,Olding, Angus,Fuller, Rebecca O.,Canty, Allan J.,Lucas, Nigel T.,Bissember, Alex C.
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supporting information
p. 2305 - 2310
(2021/05/06)
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- Nickel-Catalyzed Intramolecular 1,2-Aryl Migration of Mesoionic Carbenes (iMICs)
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Intramolecular 1,2-Dipp migration of seven mesoionic carbenes (iMICAr) 2 a–g (iMICAr=ArC{N(Dipp)}2CHC; Ar=aryl; Dipp=2,6-iPr2C6H3) under nickel catalysis to give 1,3-imidazoles (IMDAr) 3 a–g (IMDAr=ArC{N(Dipp)CHC(Dipp)N}) has been reported. The formation of 3 indicates the cleavage of an N?CDipp bond and the subsequent formation of a C?CDipp bond in 2, which is unprecedented in NHC chemistry. The use of 3 in accessing super-iMICs (5) (S-iMIC=ArC{N(Dipp)N(Me)C(Dipp)}C) has been shown with selenium (6), gold (7), and palladium (8) compounds. The quantification of the stereoelectronic properties reveals the superior σ-donor strength of 5 compared to that of classical NHCs. Remarkably, the percentage buried volume of 5 (%Vbur=45) is the largest known amongst thus far reported iMICs. Catalytic studies show a remarkable activity of 5, which is consistent with their auspicious stereoelectronic features.
- Merschel, Arne,Glodde, Timo,Neumann, Beate,Stammler, Hans-Georg,Ghadwal, Rajendra S.
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supporting information
p. 2969 - 2973
(2020/12/14)
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- Facile synthesis of NC(sp3)O pincer palladium complexes and their use as efficient catalysts for Suzuki-Miyaura reaction of aryl bromides in aqueous medium
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Two NC(sp3)O pincer palladium(II) complexes 3a-3b were readily prepared in high yields in only two steps. Of the first step, catalytic hydrophosphination of 2-alkenoylpyridines and subsequent in situ phosphine oxidation produced the NC(sp3)O pincer preligands 2a-2b. The second step is palladation of the preligands 2a-2b where PdCl2 was used as the Pd source to afford the desired Pd pincers 3a-3b via C(sp3)-H bond activation. Single crystal X-ray diffraction analysis of complex 3a unambiguously confirmed the NCO tridentate coordination mode of the complexes. The two complexes 3a-3b were applied to catalyze the Suzuki-Miyaura reaction. Complex 3b was found to be more efficient and exhibited very high activity in the Suzuki reaction of structurally diverse aryl bromides with arylboronic acids in aqueous ethanol under air. At a reaction temperature of 70 °C, a TON of up to 1.9 × 105 and a TOF of up to 9800 h?1 were achieved. At lower temperatures 3b was still very active, giving a TON of up to 9.5 × 103 and a TOF of up to 3900 h?1 at room temperature.
- Gong, Jun-Fang,Li, Nan,Pan, Ya-Ping,Song, Mao-Ping,Yang, Jing-Jing,Zhu, Zhi-Wu
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- A facile and versatile electro-reductive system for hydrodefunctionalization under ambient conditions
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A general electrochemical system for reductive hydrodefunctionalization is described, employing the inexpensive and easily available triethylamine (Et3N) as a sacrificial reductant. This protocol is characterized by facile operation, sustainable conditions, and exceptionally wide substrate scope covering the cleavage of C-halogen, N-S, N-C, O-S, O-C, C-C and C-N bonds. Notably, the selectivity and capability of reduction can be conveniently switched by simple incorporation or removal of an alcohol as a co-solvent.
- Huang, Binbin,Guo, Lin,Xia, Wujiong
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supporting information
p. 2095 - 2103
(2021/03/26)
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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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- 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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- Teflon Magnetic Stirring Capsules (TMSC) as a Practical and Reusable Delivery System for Sensitive Reagents and Catalysts
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The development of a user-friendly reusable laboratory equipment for the delivery of sensitive reagents and catalysts is described. The tightness of these Teflon Magnetic Stirring Capsules (TMSC) is ensured by the magnetic force and release of the reagent inside the solution is triggered by adjusting the stirring rate so that the centrifuge force exceeds the magnetic force. They can be loaded with several chemicals at the same time and do operate across a broad range of temperatures. The inertness of Teflon facilitates reaction purification.
- Taillemaud, Sylvain,Rosset, Stéphane,Mazet, Clément
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- Nickel- and Palladium-Catalyzed Cross-Coupling Reactions of Organostibines with Organoboronic Acids
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A strategy for the formation of antimony-carbon bond was developed by nickel-catalyzed cross-coupling of halostibines. This method has been applied to the synthesis of various triaryl- and diarylalkylstibines from the corresponding cyclic and acyclic halostibines. This protocol showed a wide substrate scope (72 examples) and was compatible to a wide range of functional groups such as aldehyde, ketone, alkene, alkyne, haloarenes (F, Cl, Br, I), and heteroarenes. A successful synthesis of arylated stibine 3 a in a scale of 34.77 g demonstrates high synthetic potential of this transformation. The formed stibines (R3Sb) were then used for the palladium-catalyzed carbon–carbon bond forming reaction with aryl boronic acids [R?B(OH)2], giving biaryls with high selectivity, even the structures of two organomoieties (R and R′) are very similar. Plausible catalytic pathways were proposed based on control experiments.
- Zhang, Dejiang,Le, Liyuan,Qiu, Renhua,Wong, Wai-Yeung,Kambe, Nobuaki
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supporting information
p. 3104 - 3114
(2020/12/11)
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- N-Aroylsulfonamide-Photofragmentation (ASAP)-A Versatile Route to Biaryls
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The photochemical fragmentation of N-aroylsulfonamides 9 (ASAP) is a powerful method for the preparation of various biaryls. Compounds 9 are easily accessible in two steps from amines by treatment with arenesulfonyl chlorides and aroyl chlorides. Many of these compounds were prepared for the first time. The irradiation takes place in a previously developed continuous-flow reactor using inexpensive UVB or UVC fluorescent lamps. Isocyanates and sulphur dioxide are formed as the only by-products. The ASAP tolerates a variety of functional groups and is even suited for the preparation of phenylnaphthalenes and terphenyls. The ASAP mechanism was elucidated by interaction of photophysical and quantum chemical (DFT) methods and revealed a spirocyclic biradical as key intermediate.
- Wessig, Pablo,Krebs, Saskia
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p. 6367 - 6374
(2021/09/29)
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