1208-86-2Relevant articles and documents
Allyl Palladium Complexes of Cycloheptatrienyl-Cyclopentadienyl Phosphane Ligands in Buchwald-Hartwig Amination Reactions
Tr?ndle, Sabrina,Freytag, Matthias,Jones, Peter G.,Tamm, Matthias
, (2019)
A series of well-defined palladium allyl chloride pre-catalysts was synthesized using previously reported troticenyl phosphane ligands [(η7-C7H7)Ti(η5-C5H4PR2)] and [(η7-C7H6PR2)Ti(η5-C5H5)] (R = Cy, tBu) as ancillary ligands. The formation of a dimeric μ-chloro-, μ-allyl-bridged PdI species was observed with the ligand [(η7-C7H7)Ti(η5-C5H4PtBu2)], whereas L2Pd0 {L = [(η7-C7H6PtBu2)Ti(η5-C5H5)]} was formed in presence of KOtPent. In addition, the catalytic activity of the palladium allyl chloride pre-catalysts was investigated in Buchwald-Hartwig amination reactions with various aryl halogenides and N-methylaniline or morpholine. The cyclohexyl derivatives show almost no catalytic activity, whereas for the tert-butyl derivatives a significant difference could be observed, depending on whether the seven-membered ring or the five-membered ring is functionalized.
Mechanistic studies of the palladium-catalyzed amination of aryl halides and the oxidative addition of aryl bromides to Pd(BINAP)2 and Pd(DPPF)2: An unusual case of zero-order kinetic behavior and product inhibition
Alcazar-Roman, Luis M.,Hartwig, John F.,Rheingold, Arnold L.,Liable-Sands, Louise M.,Guzei, Ilia A.
, p. 4618 - 4630 (2000)
Mechanistic studies of the amination of aryl bromides catalyzed by palladium complexes containing the chelating phosphines BINAP and DPPF are reported. The coupling of primary alkyl- and arylamines, secondary cyclic alkylamines, and secondary arylalkylamines with bromoarenes in the presence of stoichiometric base and Pd(BINAP)2 (1a) as catalyst, and the reaction of aniline with 4-Br-C6H4-t-Bu in the presence of base catalyzed by Pd(DPPF)2 (2), were studied. The stoichiometric oxidative additions of PhBr to 1a and to 2 were turnover limiting, and kinetic studies were also conducted on this individual step. The stoichiometric oxidative addition of PhBr to 1a showed an inverse first-order dependence on added ligand when the PhBr concentration was low but depended solely on the rate of chelating ligand dissociation at high [PhBr]. There was no measurable solvent effect. In addition, the rates were indistinguishable in the presence and in the absence of amines and salts that are present in the catalytic amination reactions. Similar qualitative data for the oxidative addition of PhBr to 2 was obtained by 1H NMR spectroscopy. The observed rate constants for the overall amination reactions catalyzed by 1a were shown to be zero order in aryl halide, amine, base, and added ligand, while they were first order in catalyst. These data indicated that the kinetic behavior of the overall reaction was dictated solely by the rate of ligand dissociation from 1a, as observed for the oxidative addition. When secondary amines were used, deviation from this behavior was observed. This anomalous behavior resulted from decay of catalyst rather than a change in the turnover-limiting step. A catalyst decomposition pathway that involves backbone P-C bond cleavage of the chelating bisphosphine ligands was revealed by the stoichiometric oxidative addition studies. Quantitative rate data were also obtained for reaction of 4-Br-C6H4-t-Bu with aniline in the presence of base catalyzed by 2. The observed rate constants were zero order in amine and base, inverse first order in added ligand, and first order in aryl bromide. At low concentration of added ligand, the reaction appeared to be first order in amine. However, this deviation from the expected behavior was due to reversible reaction of the catalyst with product.
Phosphine-functionalised polymer resins as Pd scavengers
Guinó, Meritxell,Hii, King Kuok
, p. 6911 - 6913 (2005)
Three phosphine-functionalised polymer resins were used as scavengers of palladium catalysts from Buchwald-Hartwig aryl amination reactions. The purity of the products was assessed, and residual palladium analysed by ICP-AES. Scavenging efficiencies of up to >98.5% were demonstrated.
An inexpensive cyclodiphosphazane as an efficient ligand for the palladium-catalyzed amination of aryl bromides and chlorides
Rama Suresh,Kumara Swamy
, p. 6004 - 6007 (2009)
An economic and novel ligand, cyclodiphosphazane [ClPN(t-Bu)]2 (1), was introduced in the palladium-catalyzed amination of unactivated aryl halides. The catalyst allows for the amination of aryl chlorides and bromides with secondary cyclic amines and anilines in good yields.
N(2)-Monosubstituted bishydrazides of oxalic acid as new efficient components of the system for the copper-catalyzed C-N cross-coupling in water
Kurandina,Eliseenkov,Petrov,Boyarskiy
, p. 1009 - 1013 (2012)
N(2)-Monosubstituted bishydrazides of oxalic acid in the presence of hexane-2,5-dione in situ form efficient ligands for the copper catalyzed C-N cross-coupling. A scaled pre-parative method for the synthesis of diarylamines was developed based on the results obtained.
Heteroleptic (N-heterocyclic carbene)–Pd–pyrazole (indazole) complexes: Synthesis, characterization and catalytic activities towards C–C and C–N cross-coupling reactions
Yang, Jin
, (2017)
Eight heteroleptic palladium complexes containing both N-heterocyclic carbenes and NH-heterocycle azoles (pyrazole and indazole) were synthesized and characterized, and their structures were unambiguously confirmed using single-crystal X-ray diffraction. Further investigation of the complexes as catalysts in the Suzuki–Miyaura reaction and Buchwald–Hartwig amination revealed good reactivities for aryl chlorides.
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Birch,Jenkins
, p. 119,120-122 (1975)
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Retention of palladium and phosphine ligands using nanoporous polydicyclopentadiene thimbles
Gupta, Abhinaba,Long, Tyler R.,Rethwisch, David G.,Bowden, Ned B.
, p. 10236 - 10238 (2011)
Thimbles composed of polydicyclopentadiene retained Pd and phosphines used in Buchwald-Hartwig and Sonogashira coupling reactions but allowed the products to permeate. The products were isolated in high yields on the exteriors of the thimbles with no detectable contamination from phosphine and with Pd loadings as low as 5.5 ppm.
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Chatterjee,Raychaudhuri
, p. 2546 (1968)
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General and efficient catalytic amination of aryl chlorides using a palladium/bulky nucleophilic carbene system
Huang, Jinkun,Grasa, Gabriella,Nolan, Steven P.
, p. 1307 - 1309 (1999)
(matrix prensented) A combination of palladium and an imidazolium chloride has been used as catalyst precursor in the amination of aryl chlorides. The imidazolium salt IPrHCI (4, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) was found to provide the most efficient transformation rates in this catalytic system. This new system proves general and efficient for aryl chlorides as well as aryl bromides and iodides.
Old and new Aryne precursor, anthranilic acid: Multicomponent reaction of benzyne with quinolines or imines and pronucleophiles
Fujiie, Nonoka,Nagahora, Noriyoshi,Okuma, Kentaro,Qu, Yuxuan
, p. 446 - 449 (2020)
An operationally simple one-pot protocol for the synthesis of a variety of trichloromethylated tertiary amines from anthranilic acid, imines, and chloroform was achieved. This reaction proceeds via in situ imine formation followed by the addition of benzyne prepared from anthranilic acid with concomitant proton abstraction from chloroform. By employing this method, a series of β-trichloromethylated anilines were synthesized in moderate to good yields in gram scale. Basic hydrolysis of trichloromethylated dihydoquinoline gave dichloromethylene-1-phenylquinoline in quantitative yield.
Buchwald–Hartwig Amination of Nitroarenes
Inoue, Fumiyoshi,Kashihara, Myuto,Yadav, M. Ramu,Nakao, Yoshiaki
, p. 13307 - 13309 (2017)
The Buchwald–Hartwig amination of nitroarenes was achieved for the first time by using palladium catalysts bearing dialkyl(biaryl)phosphine ligands. These cross-coupling reactions of nitroarenes with diarylamines, arylamines, and alkylamines afforded the corresponding substituted arylamines. A catalytic cycle involving the oxidative addition of the Ar?NO2 bond to palladium(0) followed by nitrite/amine exchange is proposed based on a stoichiometric reaction.
N-Heterocyclic Carbene Palladium(II) Amine Complexes: The Role of Primary Aryl- or Alkylamine Binding and Applications in the Buchwald-Hartwig Amination Reaction
Hsu, Yu-Cheng,Chen, Ming-Tsz
supporting information, (2021/12/24)
N-heterocyclic carbene-palladium(II) amine complexes bearing primary aryl- or alkylamines were synthesized. The prepared complexes were characterized by single crystal X-ray diffraction as well as NMR spectroscopy. These complexes exhibited good catalytic activities for the Buchwald-Hartwig amination reaction of aryl chlorides to afford arylated anilines under mild conditions. All reactions were carried out in air and all starting materials were used as supplied without purification. 21 expected coupling products were obtained in moderate to high yields under optimum conditions.
Mediator-Enabled Electrocatalysis with Ligandless Copper for Anaerobic Chan-Lam Coupling Reactions
Walker, Benjamin R.,Manabe, Shuhei,Brusoe, Andrew T.,Sevov, Christo S.
supporting information, p. 6257 - 6265 (2021/05/07)
Simple copper salts serve as catalysts to effect C-X bond-forming reactions in some of the most utilized transformations in synthesis, including the oxidative coupling of aryl boronic acids and amines. However, these Chan-Lam coupling reactions have historically relied on chemical oxidants that limit their applicability beyond small-scale synthesis. Despite the success of replacing strong chemical oxidants with electrochemistry for a variety of metal-catalyzed processes, electrooxidative reactions with ligandless copper catalysts are plagued by slow electron-transfer kinetics, irreversible copper plating, and competitive substrate oxidation. Herein, we report the implementation of substoichiometric quantities of redox mediators to address limitations to Cu-catalyzed electrosynthesis. Mechanistic studies reveal that mediators serve multiple roles by (i) rapidly oxidizing low-valent Cu intermediates, (ii) stripping Cu metal from the cathode to regenerate the catalyst and reveal the active Pt surface for proton reduction, and (iii) providing anodic overcharge protection to prevent substrate oxidation. This strategy is applied to Chan-Lam coupling of aryl-, heteroaryl-, and alkylamines with arylboronic acids in the absence of chemical oxidants. Couplings under these electrochemical conditions occur with higher yields and shorter reaction times than conventional reactions in air and provide complementary substrate reactivity.
Cu-Catalyzed Cross-Coupling of Nitroarenes with Aryl Boronic Acids to Construct Diarylamines
Guan, Xinyu,Zhu, Haoran,Driver, Tom G.
, p. 12417 - 12422 (2021/10/12)
The development and study of a simple copper-catalyzed reaction of nitroarenes with aryl boronic acids to form diarylamines that uses phenyl silane as the stoichiometric terminal reductant is described. This cross-coupling reaction requires as little as 2 mol % of CuX and 4 mol % of diphosphine for success and tolerates a broad range of functional groups on either the nitroarene or the aryl boronic acid to afford the amine in good yield. Mechanistic investigations established that the cross-coupling reaction proceeds via a nitrosoarene intermediate and that copper is required to catalyze both the deoxygenation of the nitroarene to afford the nitrosoarene and C-NAr bond formation of the nitrosoarene with the aryl boronic acid.
