2367-22-8Relevant articles and documents
Mono- and dinuclear palladium(II) complexes containing both N-heterocyclic carbenes and tetrazole ligands as catalysts for Hiyama coupling
Yang, Jin
, p. 9739 - 9745 (2016)
Treatment of the dimeric compounds [Pd(μ-Cl)(Cl)(NHC)]2 with tetrazole ligands afforded a series of tetrazole ligand stabilized NHC-Pd complexes, including [PdCl2(IPr)(1H-tetrazole)] (1), [PdCl2(SIPr)(1H-tetrazole)] (2), [PdCl2(IPr)(1-phenyl-1H-tetrazole)] (3), [PdCl2(SIPr)(1-phenyl-1H-tetrazole)] (4), [Pd2(μ-Cl)(μ-5-phenyl-2H-tetrazole)Cl2(IPr)2] (5) and [Pd2(μ-Cl)(μ-5-pheny-2H-ltetrazole)Cl2(SIPr)2] (6) [IPr = N,N′-bis-(2,6-di(isopropyl)phenyl)imidazol-2-ylidene; SIPr = N,N′-bis-(2,6-di(isopropyl)phenyl)imidazolidin-2-ylidene]. Notably, compounds 1-4 are mononuclear NHC-Pd complexes, while compounds 5 and 6 show unprecedented μ-Cl and μ-5-phenyl-2H-tetrazole bridged dinuclear structures. The catalytic properties of the obtained NHC-Pd complexes in Hiyama coupling were initially investigated.
First solid-state structures of real diorganyl phosphinous acids R 2POH (R=CF3, C2F5)
Bader, Julia,Berger, Raphael J. F.,Stammler, Hans-Georg,Mitzel, Norbert W.,Hoge, Berthold
, p. 13420 - 13423 (2011)
Ring or chain? The two known phosphinous acids, (CF3) 2POH and (C2F5)2POH, reveal hydrogen-bridged aggregates in the solid state (see figure). The CF3 derivative forms helical chains, whereas the increased sterical demand of the C2F5 group leads to the formation of tetramers. The high catalytic activity of their palladium complexes (TON24500) is highlighted in the field of cross-coupling reactions. Copyright
Biogenous iron oxide-immobilized palladium catalyst for the solvent-free Suzuki-Miyaura coupling reaction
Mandai, Kyoko,Korenaga, Toshinobu,Ema, Tadashi,Sakai, Takashi,Furutani, Mitsuaki,Hashimoto, Hideki,Takada, Jun
, p. 329 - 332 (2012)
Iron oxide produced by iron-oxidizing bacteria, Leptothrix ochracea, (biogenous iron oxide: BIO) was used as a support for immobilized palladium catalysts with organic cross-linkers. Palladium immobilized on BIO bearing imidazolium chloride delivered the desired biaryl products in sufficient yields in the Suzuki-Miyaura coupling reactions under solvent-free conditions and could be reused several times without significant loss of catalytic activity. It is shown that BIO can be exploited as a useful support for immobilization of palladium and the BIO-immobilized palladium catalyst effectively promotes the solvent-free Suzuki-Miyaura coupling reactions.
Air-stable and catalytically active phosphinous acid transition-metal complexes
Kurscheid, Boris,Belkoura, Lhoussaine,Hoge, Berthold
, p. 1329 - 1334 (2012)
Secondary phosphane oxides R2P(O)H are most frequently used as preligands for phosphinous acid R2POH (R = alkyl, aryl) transition-metal complexes, which are very efficient catalysts for cross-coupling reactions. To investigate the influence of electron-deficient substituents on the catalytic activity, the coordination properties of bis(trifluoromethyl)-, bis(pentafluoroethyl)-, and bis[2,4-bis(trifluoromethyl) phenyl]phosphinous acid toward catalytically relevant metals, such as palladium and platinum, are studied. The novel phosphinous acid palladium complexes reveal a high catalytic activity in Heck and Suzuki cross-coupling reactions. Because of the strong dependence of these processes on the reaction conditions, a systematic solvent and base screening with 1-bromo-3-fluorobenzene and phenyl boronic acid as model reactants is performed. The most efficient solvent/base system consists of 2-propanol and potassium phosphate, providing a full conversion and a TON of around 10 000 after 20 h at room temperature with a catalyst loading of 0.01 mol % palladium. A catalyst loading of only 0.004 mol % palladium still leads to a nearly full conversion after 20 h at room temperature. During the catalytic reaction, the formation of the corresponding phosphinic acid R2P(O)OH is observed. Further investigations lead to the conclusion that palladium nanoparticles represent the catalytically active species. We also succeeded in the generation of palladium nanoparticles, which exhibit an extremely high catalytic activity in Suzuki cross-coupling reaction with TONs over 60 000 and TOFs larger than 40 000.
Cerium photosensitizers: Structure-function relationships and applications in photocatalytic aryl coupling reactions
Yin, Haolin,Carroll, Patrick J.,Manor, Brian C.,Anna, Jessica M.,Schelter, Eric J.
, p. 5984 - 5993 (2016)
Two complete mixed-ligand series of luminescent CeIII complexes with the general formulas [(Me3Si)2NC(NiPr)2]xCeIII[N(SiMe3)2]3-x (x = 0, 1-N; x = 1, 2-N, x = 2, 3-N; x = 3, 4) and [(Me3Si)2NC(NiPr)2]xCeIII(OAr)3-x (x = 0, 1-OAr; x = 1, 2-OAr, x = 2, 3-OAr; x = 3, 4) were developed, featuring photoluminescence quantum yields up to 0.81(2) and lifetimes to 117(1) ns. Although the 4f ? 5d absorptive transitions for these complexes were all found at ca. 420 nm, their emission bands exhibited large Stokes shifts with maxima occurring at 553 nm for 1-N, 518 nm for 2-N, 508 nm for 3-N, and 459 nm for 4, featuring yellow, lime-green, green, and blue light, respectively. Combined time-dependent density functional theory (TD-DFT) calculations and spectroscopic studies suggested that the long-lived 2D excited states of these complexes corresponded to singly occupied 5d 2 orbitals. The observed difference in the Stokes shifts was attributed to the relaxation of excited states through vibrational processes facilitated by the ligands. The photochemistry of the sterically congested complex 4 was demonstrated by C-C bond forming reaction between 4-fluoroiodobenzene and benzene through an outer sphere electron transfer pathway, which expands the capabilities of cerium photosensitizers beyond our previous results that demonstrated inner sphere halogen atom abstraction reactivity by 1-N.
Coordination Properties of Perfluoroethyl- and Perfluorophenyl-Substituted Phosphonous acids, RfP(OH)2
Allefeld, Nadine,Kurscheid, Boris,Neumann, Beate,Stammler, Hans-Georg,Ignat'Ev, Nikolai,Hoge, Berthold
, p. 13666 - 13675 (2015)
Phosphinic acids, RfP(O)(OH)H (Rf=CF3, C2F5, C6F5), turned out to be excellent preligands for the coordination of phosphonous acids, RfP(OH)2. Addition of C2F5P(O)(OH)H to solid PtCl2 under different reaction conditions allows the isolation and full characterization of the mononuclear complexes [ClPt{P(C2F5)(OH)O}{P(C2F5)(OH)2}2] and [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}] containing hydrogen-bridged [RfP(OH)O]- and RfP(OH)2 units. Further deprotonation of [Pt{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] leads to the formation of the dianionic platinate, [Pt{P(C2F5)(OH)O}4]2-, revealing four intramolecular hydrogen bridges. With PdCl2 the dinuclear complex [Pd2(μ-Cl)2{[P(C2F5)(OH)O]2H}2] was isolated and characterized. The Cl- free complex [Pd{P(C2F5)(OH)O}2{P(C2F5)(OH)2}2] was also prepared and deprotonated to the dianionic palladate, [Pd{P(C2F5)(OH)O}4]2-. Both compounds were characterized by NMR spectroscopy, IR spectroscopy, and X-ray analyses. In addition, the C6F5 derivatives [ClPt{P(C6F5)(OH)O}{P(C6F5)(OH)2}2] and [Pd2(μ-Cl)2{[P(C6F5)(OH)O]2H}2] as well as the CF3 derivative [Pd2(μ-Cl)2{[P(CF3)(OH)O]2H}2] were synthesized and fully characterized. Phosphonous acid complexes are inert towards air and moisture and can be stored for several months without decomposition. The catalytic activity of the palladium complexes in the Suzuki cross-coupling reaction between 1-bromo-3-fluorobenzene and phenyl boronic acid was demonstrated. A tautomeric equilibrium between phosphinic, RP(O)(OH)H, and phosphonous acids, RP(OH)2, is evidenced by this work (see figure). The coordination properties of phosphonous acids with electron-withdrawing CF3, C2F5, and C6F5 groups is also described.
Organocatalytic synthesis of (Het)biaryl scaffoldsviaphotoinduced intra/intermolecular C(sp2)-H arylation by 2-pyridone derivatives
Das, Tapas Kumar,Kundu, Mrinalkanti,Mondal, Biswajit,Ghosh, Prasanjit,Das, Sajal
, p. 208 - 218 (2021/12/29)
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.
Efficient and Economical Preparation of Hypercrosslinked Polymers-palladium Based on Schiff Base as Recyclable Catalyst for Suzuki-Miyaura Reactions
Gao, Xiyue,Lin, Hongwei,Liu, Shasha,Luo, Qionglin,Ouyang, Yuejun,Xiang, Bailin,Xiang, Dexuan,Yao, Huan,Zhang, Li
supporting information, p. 1879 - 1882 (2021/10/29)
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.
Anchored PdCl2 on fish scale: an efficient and recyclable catalyst for Suzuki coupling reaction in aqueous media
Yang, Quanlu,Yang, Fawang,Zhang, Ying,Hou, Juanjuan,Li, Jiankun,Cheng, Jinkui,Wu, Shang,Zhan, Huiying,Zhang, Xinghui,Shi, Haixiong
supporting information, (2020/12/25)
PdCl2 anchored on fish scale (FS) complex were intended to a heterogeneous catalyst for ligand-free Suzuki coupling reaction in aqueous media. The catalyst FS-PdCl2 was characterized by FT-IR, powder XRD, XPS and SEM. FS-PdCl2 complex has been successfully implemented for Suzuki coupling reactions of various halogenated aromatics with arylboronic acid to provide the corresponding biaryl compounds under environmentally friendly conditions (40 °C, water solvent). Moreover, the efficient catalyst shows excellent stability and recyclability, and its catalytic activity without any decrease after 8 times consecutive reused.
Sulfonate Versus Sulfonate: Nickel and Palladium Multimetallic Cross-Electrophile Coupling of Aryl Triflates with Aryl Tosylates
Kang, Kai,Huang, Liangbin,Weix, Daniel J.
supporting information, p. 10634 - 10640 (2020/07/08)
While phenols are frequent and convenient aryl sources in cross-coupling, typically as sulfonate esters, the direct cross-Ullmann coupling of two different sulfonate esters is unknown. We report here a general solution to this challenge catalyzed by a combination of Ni and Pd with Zn reductant and LiBr as an additive. The reaction has broad scope, as demonstrated in 33 examples (65% ± 11% average yield). Mechanistic studies show that Pd strongly prefers the aryl triflate, the Ni catalyst has a small preference for the aryl tosylate, aryl transfer between catalysts is mediated by Zn, and Pd improves yields by consuming arylzinc intermediates.
