- Radical and ionic mechanisms in rearrangements of o-tolyl aryl ethers and amines initiated by the Grubbs-stoltz reagent, et3SiH/KOtbu
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Rearrangements of o-tolyl aryl ethers, amines, and sulfides with the Grubbs-Stoltz reagent (Et3SiH + KOtBu) were recently announced, in which the ethers were converted to o-hydroxydiarylmethanes, while the (o-tol)(Ar)NH amines were transformed into dihydroacridines. Radical mechanisms were proposed, based on prior evidence for triethylsilyl radicals in this reagent system. A detailed computational investigation of the rearrangements of the aryl tolyl ethers now instead supports an anionic Truce-Smiles rearrangement, where the initial benzyl anion can be formed by either of two pathways: (i) direct deprotonation of the tolyl methyl group under basic conditions or (ii) electron transfer to an initially formed benzyl radical. By contrast, the rearrangements of o-tolyl aryl amines depend on the nature of the amine. Secondary amines undergo deprotonation of the N-H followed by a radical rearrangement, to form dihydroacridines, while tertiary amines form both dihydroacridines and diarylmethanes through radical and/or anionic pathways. Overall, this study highlights the competition between the reactive intermediates formed by the Et3SiH/KOtBu system.
- Kolodziejczak, Krystian,Murphy, John A.,Stewart, Alexander J.,Tuttle, Tell
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- 1,2-Difunctionalization of Aryl Triflates: A Direct and Modular Access to Diversely Functionalized Anilines
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ortho-Amino difunctionalization of aryl triflates has been achieved via a three-component reaction. The cascade reaction proceeds through a zincate base-mediated deprotonative formation of a reactive aryne intermediate, in situ nucleophilic addition, and coupling with electrophilic partners. This strategy leverages the advantageous reactivity of organozincate intermediates, enabling the installation of various functionalities such as amine, azide, oxygen, sulfur, halide, alkynyl, aryl, vinyl, and alkyl groups in a modular manner for the synthesis of diverse aniline skeletons.
- Cho, Seoyoung,Wang, Qiu
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supporting information
(2020/02/28)
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- A Highly Active Ylide-Functionalized Phosphine for Palladium-Catalyzed Aminations of Aryl Chlorides
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Ylide-functionalized phosphine ligands (YPhos) were rationally designed to fit the requirements of Buchwald–Hartwig aminations at room temperature. This ligand class combines a strong electron-donating ability comparable to NHC ligands with high steric demand similar to biaryl phosphines. The active Pd species are stabilized by agostic C?H???Pd rather than by Pd–arene interactions. The practical advantage of YPhos ligands arises from their easy and scalable synthesis from widely available, inexpensive starting materials. Benchmark studies showed that YPhos-Pd complexes are superior to the best-known phosphine ligands in room-temperature aminations of aryl chlorides. The utility of the catalysts was demonstrated by the synthesis of various arylamines in high yields within short reaction times.
- Weber, Philip,Scherpf, Thorsten,Rodstein, Ilja,Lichte, Dominik,Scharf, Lennart T.,Goo?en, Lukas J.,Gessner, Viktoria H.
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supporting information
p. 3203 - 3207
(2019/01/09)
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- Direct arylation of tertiary amines via aryne intermediates using diaryliodonium salts
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With a strategy by using diaryliodonium salts as the precursors of benzynes, direct N-arylation of tertiary amines with diaryliodonium salts was reported. Thus, the desired aromatic tertiary amines with a wide range of substituents were synthesized in moderate to excellent yields of 55–91%.
- Zhang, Zhiang,Wu, Xunshen,Han, Jianwei,Wu, Wenjun,Wang, Limin
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supporting information
p. 1737 - 1741
(2018/04/02)
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- Solvent-free mechanochemical Buchwald-Hartwig amination of aryl chlorides without inert gas protection
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A solvent-free Buchwald-Hartwig amination had been developed under high-speed ball-milling conditions, which afforded the desired products with moderate to high yields. The addition of sodium sulfate was found to be crucial for improving both the performance and the reproducibility. Comparative solvent-free stirring experiments implicated the importance of mechanical interaction for the transformation, and the inert gas was proved to be unnecessary for this amination.
- Shao, Qiao-Ling,Jiang, Zhi-Jiang,Su, Wei-Ke
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supporting information
p. 2277 - 2280
(2018/05/16)
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- NIXANTPHOS: A highly active ligand for palladium catalyzed Buchwald-Hartwig amination of unactivated aryl chlorides
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Xantphos is one of the two most common ligands used in palladium catalyzed Buchwald-Hartwig amination reactions, because of its broad scope and high probability of success. It does not, however, work well with unactivated aryl chlorides. Herein NIXANTPHOS is compared to Xantphos and an array of mono- and bidentate phosphines. NIXANTPHOS outperforms Xantphos and all other bidentate ligands examined. Under the optimal reaction conditions, unactivated aryl chlorides afford the expected products in good to excellent yield with as low as 0.05 mol% (500 ppm) palladium loading.
- Mao, Jianyou,Zhang, Jiadi,Zhang, Shuguang,Walsh, Patrick J.
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supporting information
p. 8690 - 8696
(2018/07/13)
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- A mechanical to urge the enters the carbon - [...] forming method (by machine translation)
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The invention discloses a mechanical to urge the enters the carbon - [...] forming method, said method comprising: in order to type 2 shown in formulae of organic amine 3 shown the chlorinated aromatic hydrocarbon as the raw material, the catalyst, ligand, in the presence of alkali and additive, the reaction is carried out by the mechanical grinding method, after the reaction mixture after the separation and purification, obtains the type 1 compound shown; in the present invention relates to mechanical grinding promotion to the chlorinated aromatic hydrocarbon as the substrate of the Buchwald - Hartwig reaction mainly adopts the organic phosphonate ligands, in the palladium catalyst under the action of the organic amine compound with the chlorinated aromatic hydrocarbon of the between the coupling, so as to obtain high yield of the target product, the majority of the reaction can be 90% or more yield. The mild reaction conditions, can be in the 1 - 2 H to complete the reaction. (by machine translation)
- -
-
Paragraph 0042; 0043; 0044; 0046; 0047
(2018/09/21)
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- Flexible Steric Bulky Bis(Imino)acenaphthene (BIAN)-Supported N-Heterocyclic Carbene Palladium Precatalysts: Catalytic Application in Buchwald-Hartwig Amination in Air
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To achieve efficient palladium-catalyzed cross-coupling reaction under mild reaction conditions with the flexible steric bulk strategy, a series of Pd-PEPPSI (PEPPSI: pyridine-enhanced precatalyst preparation, stabilization, and initiation) complexes C1-C6 were synthesized and characterized, in which unsymmetric flexible steric bulk was introduced on the N-aryl of ancenaphthyl skeleton. These well-defined palladium complexes were found to be excellent precatalysts for Buchwald-Hartwig amination of aryl chlorides with amines in air. The electronic effect of the Pd-PEPPSI complexes and the effect of ancillary pyridine ligands were evaluated, among which complex C3 exhibited the most efficiency. It was demonstrated that the cross-coupling products were obtained in excellent yields in the presence of 0.5-0.1 mol % palladium loading. A wide range of aryl- and heteroaryl chlorides as well as various amines were compatible. The oxidative addition of aryl chlorides is revealed to be the rate-determining step in the catalytic cycle. The catalytic activity can be enhanced by introducing electron-donating groups to the Pd-PEPPSI complexes. This type of Pd-PEPPSI precatalyst showed the most efficiency reported to date for the challenging C-N cross-coupling reactions requiring no anhydrous and inert atmosphere protections, suggesting flexible steric bulk as a promising catalyst design strategy.
- Lan, Xiao-Bing,Li, Yinwu,Li, Yan-Fang,Shen, Dong-Sheng,Ke, Zhuofeng,Liu, Feng-Shou
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p. 2914 - 2925
(2017/03/23)
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- Application of a 2-aryl indenylphosphine ligand in the Buchwald-Hartwig cross-coupling reactions of aryl and heteroaryl chlorides under the solvent-free and aqueous conditions
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An efficient solvent-free protocol for the Buchwald-Hartwig cross-coupling reaction of aryl and heteroaryl chlorides with primary and secondary amines using the Pd(dba)2/ligand 1 catalytic system has been developed. Notably, the catalytic system also efficiently catalyzed the reaction under aqueous conditions.
- Liu, Yan,Yuan, Jia,Wang, Zi-Fei,Zeng, Si-Hao,Gao, Meng-Yue,Ruan, Mei-Lin,Chen, Jian,Yu, Guang-Ao
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supporting information
p. 5805 - 5810
(2017/07/22)
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- An Expedient Synthesis of Carbazoles through Potassium tert-Butoxide-Promoted Intramolecular Direct C–H Bond Arylation
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Transition-metal-free access to carbazoles was achieved through base-mediated intramolecular C–C bond formation. Reactions of N-substituted o-halodiarylamines with potassium tert-butoxide in the presence of ethylene glycol or 1,10-phenanthroline provided carbazoles in moderate to excellent yields. This transformation may proceed through a radical pathway according to a control experiment with a radical scavenger.
- Lin, Songbo,He, Xingrui,Meng, Jinpeng,Gu, Haining,Zhang, Peizhi,Wu, Jun
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p. 443 - 447
(2017/02/05)
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- Water-soluble palladacycles containing hydroxymethyl groups: Synthesis, crystal structures and use as catalysts for amination and Suzuki coupling of reactions
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Two water-soluble monophosphine [PPh3 and 2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl(Sphos)]-palladacycles containing hydroxymethyl groups 2-3 were prepared by cyclopalladation and chloride bridge-splitting reactions. The complexes were characterized by elemental analysis, ESI-MS and NMR. In addition, single-crystal X-ray analysis reveals that they have one-dimensional lamellar structures involving intermolecular hydrogen bonds and π-π interactions. The use of these palladacycles as catalysts for amination and Suzuki coupling of aryl chlorides in water was investigated. Complex 3 was found to be very efficient for these coupling reactions. Additionally, it was also successfully used in Suzuki coupling of (hydroxymethyl)phenylboronic acid for the synthesis of substituted 2-N-heterocyclic biarylmethanols.
- Han, Xin,Li, Hong-Mei,Xu, Chen,Xiao, Zhi-Qiang,Wang, Zhi-Qiang,Fu, Wei-Jun,Hao, Xin-Qi,Song, Mao-Ping
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p. 403 - 411
(2016/04/19)
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- An easily available N-heterocyclic carbene–palladium(II) catalyst for Buchwald–Hartwig amination of aryl chlorides
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Abstract: An easily available N-heterocyclic carbene–palladium(II) complex was found to be an efficient catalyst for the Buchwald–Hartwig amination of aryl chlorides. Both secondary and primary amines were tolerated under the same reaction conditions. Under the optimal conditions, all reactions proceeded successfully to give the desired products in good to high yields within hours. Graphical Abstract: [Figure not available: see fulltext.]
- Wang, Tao,Xu, Kai,Liu, Lantao,Xie, Huanping,Li, Ying,Zhao, Wen-Xian
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p. 525 - 529
(2016/07/20)
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- Solvent-free Buchwald-Hartwig reaction of aryl and heteroaryl halides with secondary amines
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A highly efficient solvent-free protocol for the Buchwald-Hartwig amination of (hetero)aryl halides by secondary amines was developed. The reaction is mediated by a Pd(OAc)2/RuPhos catalytic system in air. Various (hetero)aryl halides were coupled with diaryl, alkyl-aryl, and dialkylamines in good to excellent yields (51 examples, 50-99% yield). Copyright
- Topchiy, Maxim A.,Asachenko, Andrey F.,Nechaev, Mikhail S.
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p. 3319 - 3322
(2014/06/09)
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- SYNTHESES OF N-HETEROCYCLIC CARBENES AND INTERMEDIATES THEREFOR
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A method of preparing a 2,6 disubstituted anilines includes, reacting a 2-amino isophtha!ic acid diester with sufficient Grignard reagent R2CH2MgX to form the corresponding diol product, dehydrating the diol product to the corresponding dialkene; and hydrogenating the diol product to form the corresponding aniline. The 2,6 disubstituted anilines can be used to produce N-Heterocyciic Carbenes (NHCs). The NHCs can find application in various fields such as organic synthesis, catalysis and macromolecular chemistry. Palladium catalysts containing the NHCs are also described.
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Page/Page column 46; 47
(2014/07/23)
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- Modular synthesis of functionalisable alkoxy-tethered N-heterocyclic carbene ligands and an active catalyst for buchwald-hartwig aminations
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Modular syntheses of functionalised, alkoxy-tethered 1,3-bis(2,4,6- trimethylphenyl)imidazolium (IMes*H+) and 1,3-bis(2,6- diisopropylphen-l)imidazolium (IPr*H+) derivatives 1,3-bis(4-alkyl- -2,4,6-trimethylphenyl)imidazolium (IXyOR*H+) and 1,3-bis(4-alkyl-oxy-2,6-diisopropylphenyl)imidazolium (IPrOR*H +) are reported. A reliable synthesis of the key starting material 4-amino-3,5-diisopropylphenol is also described. Etherification of hydroxydecorated ligand intermediates before formation of the imidazolium core and subsequent modification, or direct etherification of the versatile synthon IPrOH·HCl, allowed access to various linker types including triethoxysilyl, primary amino and norbornenyl, which are not accessible by other methods. An IPrOR-palladium(II) complex was prepared, and its catalytic activity was evaluated in challenging Buchwald- Hartwig aminations of aryl chlorides. This precatalyst displayed excellent activity and selectivity under mild reaction conditions, achieving in some cases a 10-fold improvement in TOF relative to the IPr-based version. An unexpected activity profile was observed wherein sterically demanding anilines were coupled more easily than those lacking orthosubstitution.
- Krinsky, Jamin L.,Martinez, Alberto,Godard, Cyril,Castillon, Sergio,Claver, Carmen
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supporting information
p. 460 - 474
(2014/05/20)
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- [Pd(IPr*OMe)(acac)Cl]: Tuning the N-heterocyclic carbene in catalytic C-N bond formation
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A new N-heterocyclic ligand IPr*OMe [N,N′-bis(2,6- bis(diphenylmethyl)-4-methoxyphenyl)imidazol-2-ylidene] has been synthesized and compared with its earlier methyl-substituted congener IPr* [N,N′-bis(2,6-bis(diphenylmethyl)-4-methylphenyl)imidazol-2-ylidene]. IPr*OMe was successfully bound to palladium, and the catalytic activity of the resulting complex [Pd(IPr*OMe)(acac)Cl] was investigated in Buchwald-Hartwig arylamination. Catalytic activity was compared to that of [Pd(IPr*)(acac)Cl].
- Meiries, Sebastien,Speck, Klaus,Cordes, David B.,Slawin, Alexandra M. Z.,Nolan, Steven P.
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p. 330 - 339
(2013/02/25)
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- Effect of electronic enrichment of NHCs on the catalytic activity of [Pd(NHC)(acac)Cl] in Buchwald-Hartwig coupling
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A series of [Pd(NHC)(acac)Cl] (NHC = N-heterocyclic carbene) complexes have been synthesized and characterized to investigate the electronic and steric effects of NHC ligands in catalysis. Their reactivity in Buchwald-Hartwig coupling has been explored an
- Le Duc, Gaetan,Meiries, Sebastien,Nolan, Steven P.
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supporting information
p. 7547 - 7551
(2014/04/03)
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- Buchwald-Hartwig amination of (hetero)aryl chlorides by employing Mor-DalPhos under aqueous and solvent-free conditions
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We report on the application of the [Pd(cinnamyl)Cl]2/Mor- DalPhos catalyst system in the Buchwald-Hartwig amination of (hetero)aryl chlorides with primary or secondary amines conducted either under aqueous conditions without the use of co-solvents and/or surfactants or under solvent-free conditions (52 examples). We have established that reactions of this type can be conducted without the rigorous exclusion of air, and in the case of the solvent-free reactions, we have demonstrated that appropriately selected liquid and solid reagents can be employed successfully.
- Tardiff, Bennett J.,Stradiotto, Mark
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supporting information; experimental part
p. 3972 - 3977
(2012/08/27)
-
- Synthesis and X-ray structure determination of highly active Pd(II), Pd(I), and Pd(0) complexes of Di(tert -butyl)neopentylphosphine (DTBNpP) in the arylation of amines and ketones
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The air-stable complex Pd(eta;3-allyl)(DTBNpP)Cl (DTBNpP = di(tert-butyl)neopentylphosphine) serves as a highly efficient precatalyst for the arylation of amines and enolates using aryl bromides and chlorides under mild conditions with yields ranging from 74% to 98%. Amination reactions of aryl bromides were carried out using 1-2 mol % Pd(η3-allyl)(DTBNpP)Cl at 23-50 °C without the need to exclude oxygen or moisture. The C-N coupling of the aryl chlorides occurred at relatively lower temperature (80-100 °C) and catalyst loading (1 mol %) using the Pd(eta;3-allyl) (DTBNpP)Cl precatalyst than the catalyst generated in situ from DTBNpP and Pd2(dba)3 (100-140 °C, 2-5 mol % Pd). Other Pd(DTBNpP)2-based complexes, (Pd(DTBNpP)2 and Pd(DTBNpP)2Cl2) were ineffective precatalysts under identical conditions for the amination reactions. Both Pd(DTBNpP)2 and Pd(DTBNpP)2Cl2 precatalysts gave nearly quantitative conversions to the product in the α-arylation of propiophenone with p-chlorotoluene and p-bromoanisole at a substrate/catalyst loading of 100/1. At lower substrate/ca'alyst loading (1000/1), the conversions were lower but comparable to that of Pd(t-Bu3P)2. In many cases, the tri-tert-butylphosphine (TTBP) based Pd(I) dimer, [Pd(μ-Br)(TTBP)] 2, stood out to be the most reactive catalyst under identical conditions for the enolate arylation. Interestingly, the air-stable Pd(I) dimer, Pd2(DTBNpP)2(μ-Cl)(μ-allyl), was less active in comparison to [Pd(μ-Br)(TTBP)]2 and Pd(eta;3-allyl) (DTBNpP)Cl. The X-ray crystal structures of Pd(eta;3-allyl)(DTBNpP) Cl, Pd(DTBNpP)2Cl2, Pd(DTBNpP)2, and Pd 2(DTBNpP)2(μ-Cl)(μ-allyl) are reported in this paper along with initial studies on the catalyst activation of the Pd(eta;3-allyl)(DTBNpP)Cl precatalyst.
- Hill, Lensey L.,Crowell, Jason L.,Tutwiler, Strudwick L.,Massie, Nicholas L.,Hines, C. Corey,Griffin, Scott T.,Rogers, Robin D.,Shaughnessy, Kevin H.,Grasa, Gabriela A.,Johansson Seechurn, Carin C. C.,Li, Hongbo,Colacot, Thomas J.,Chou, Joe,Woltermann, Christopher J.
-
supporting information; experimental part
p. 6477 - 6488
(2010/12/24)
-
- Transition metal-free amination of aryl halides-A simple and reliable method for the efficient and high-yielding synthesis of N-arylated amines
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A simple and reliable reaction protocol for the clean, fast, and high-yielding synthesis of various N-arylated amines derived from reactions of aryl halides with various (also sterically hindered) amines under transition metal-free reaction conditions is presented. Dioxane and KN(Si(CH3)3)2 were found to be the ideal solvent and base for this transformation. The conversion rates and yields observed are excellent and in the majority of the reactions performed significantly higher than that obtained in their catalyzed versions. Furthermore, the selective synthesis of 6-halopyridin-2-amines and asymmetric pyridine-2,6-diamines (derived from consecutive reactions of 2,6-dibromopyridine and 2,6-dichloropyridine, respectively, with different amines) is possible in almost quantitative yields (relative to 2,6-dihalopyridine) within very short reaction times. Purification of the 6-halopyridin-2-amine intermediates is not necessary, allowing the synthesis of pyridine-2,6-diamines in 'one-pot'. However, catalysts are in many cases not required to efficiently and selectively couple aryl halides with amines, making transition metal-free versions of the Buchwald-Hartwig reaction extremely attractive for the synthesis of N-arylated amines with substrates containing substituents on the aryl halide, which either promote regioselectivity and/or do not require regioselective aminations.
- Bolliger, Jeanne L.,Frech, Christian M.
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supporting information; experimental part
p. 1180 - 1187
(2009/04/10)
-
- Neopentylphosphines as effective ligands in palladium-catalyzed cross-couplings of aryl bromides and chlorides
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The use of neopentylphosphine ligands in the palladium-catalyzed Suzuki, Sonogashira, Heck, and Hartwig-Buchwald couplings of aryl bromides and chlorides are reported. Di-tert-butylneopentylphosphine (DTBNpP) provided highly active catalysts for the coupling of aryl bromides at mild temperatures. Trineopentylphosphine, an air-stable trialkylphosphine, gave inactive catalysts at room temperature, but showed good activity in the H-B amination of aryl chlorides at elevated temperatures.
- Hill, Lensey L.,Smith, Joanna M.,Brown, William S.,Moore, Lucas R.,Guevera, Paul,Pair, Emily S.,Porter, Jake,Chou, Joe,Wolterman, Christopher J.,Craciun, Raluca,Dixon, David A.,Shaughnessy, Kevin H.
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p. 6920 - 6934
(2008/09/21)
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- Carbene adduct of cyclopalladated ferrocenylimine as an efficient catalyst for the amination of aryl chlorides
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A novel air- and moisture-stable carbene adduct of cyclopalladated ferrocenylimine has been synthesized and characterized. The structure of this compound was determined by X-ray crystal structure analysis. This adduct has been applied as an efficient catalyst for the amination of aryl chlorides.
- Li, Jingya,Cui, Mengjun,Yu, Ajuan,Wu, Yangjie
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p. 3732 - 3742
(2008/02/08)
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- A novel (2,2-diarylvinyl)phosphine/palladium catalyst for effective aromatic amination
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A new series of diarylvinylphosphine ligands was designed and synthesized. A catalyst system, consisting of the ligands and palladium species, effectively catalyzed the coupling reaction of aryl bromides and chlorides with amines to afford the corresponding products in good to excellent yields. The efficiency is likely derived from an interaction between the palladium center and the cisaryl moiety on the diarylvinylphosphine ligand stabilizing a catalytic intermediate during the coupling reaction.
- Suzuki, Ken,Hori, Yoji,Nishikawa, Takenobu,Kobayashi, Tohru
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p. 2089 - 2091
(2008/09/18)
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- Bulky alkylphosphines with neopentyl substituents as ligands in the amination of aryl bromides and chlorides
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Di(tert-butyl)neopentylphosphine (DTBNpP) in combination with palladium sources provided catalysts with comparable or better activity for the Hartwig-Buchwald amination of aryl bromides than tri(tert-butyl)phosphine (TTBP) under mild conditions. DTBNpP also provided effective catalysts for amination reactions of aryl chlorides at elevated temperatures. Further replacement of tert-butyl groups with neopentyl substituents resulted in less effective ligands for amination reactions. Computationally derived cone angles showed that replacement of a tert-butyl group with a neopentyl group significantly increased the cone angle of the phosphine. The larger cone angle of DTBNpP than TTBP appears to correlate with the higher activity of catalysts derived from DTBNpP in the amination of aryl bromides. TTBP is a stronger electron donor than DTBNpP, which may explain the higher activity for TTBP-derived catalysts toward aryl chlorides.
- Hill, Lensey L.,Moore, Lucas R.,Huang, Rongeai,Craciun, Raluca,Vincent, Andrew J.,Dixon, David A.,Chou, Joe,Woltermann, Christopher J.,Shaughnessy, Kevin H.
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p. 5117 - 5125
(2007/10/03)
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- CLICKPHOSPHINES FOR TRANSITION METAL-CATALYZED REACTIONS
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Phosphine triazole ligand compounds, prepared through click chemistry, complex with transition metals to form transition metal-phosphine triazole ligand complexes. These complexes are useful catalysts in coupling reactions such as Suzuki-Miyaura coupling, Stille coupling, Negishi coupling, Sonagashira coupling, carbon-heteroatom bond-forming reactions (C-O and C-N), alpha alkylation of carbonyls, Heck coupling reactions, and hydrogenation reactions.
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Page/Page column 28-29; 39
(2010/11/25)
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- Phospha-adamantanes as ligands for organopalladium chemistry: Aminations of aryl halides
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The use of Pd2dba3·CHCl3 and 1,3,5,7-tetramethyl-2,4,8-trioxa-6-phenyl-6-phospha-adamantane has been shown to facilitate the effective amination of aryl halides with aromatic or aliphatic amines in high yields.
- Gerristma, David,Brenstrum, Timothy,McNulty, James,Capretta, Alfredo
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p. 8319 - 8321
(2007/10/03)
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- New ligands for a general palladium-catalyzed amination of aryl and heteroaryl chlorides
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The synthesis and application of monodentate N-substituted heteroarylphosphines is described. In general, the ligands are conveniently prepared by selective metallation at the 2-position of the respective N-substituted heterocycle (pyrrole, indole) by using n-butyllithium/ tetramethylethylenediamine (TMEDA) followed by quenching with dialkyl- or diarylchlorophosphines. Of the different ligands prepared, the new dialkyl-2-(N-arylindolyl)phosphines (cataCXium P) perform excellently in the palladium-catalyzed amination of aryl and heteroaryl chlorides. Coupling of both activated and deactivated chloroarenes proceeds under mild conditions (room temperature to 60°C). By using optimized conditions remarkable catalyst productivity (total turnover number, TON, up to 8000) and activity (turnover frequency, TOF = 14000 h-1 at 75% conversion) are observed.
- Rataboul, Franck,Zapf, Alexander,Jackstell, Ralf,Harkal, Surendra,Riermeier, Thomas,Monsees, Axel,Dingerdissen, Uwe,Beller, Matthias
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p. 2983 - 2990
(2007/10/03)
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- NITROGEN-CONTAINING MONODENTATE PHOSPHINES AND THEIR USE IN CATALYSIS
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The present invention relates to novel nitrogen-containing monodentate phosphane ligands of formula (I) and to their use in catalytic reactions, especially in the improvement of haloaromatic compounds.
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- Catalyst for aromatic C—O, C—N, and C—C bond formation
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The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.
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- Air stable, sterically hindered ferrocenyl dialkylphosphines for palladium-catalyzed C-C, C-N, and C-O bond-forming cross-couplings
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Pentaphenylferrocenyl di-tert-butylphosphine has been prepared in high yield from a two-step synthetic procedure, and the scope of various cross-coupling processes catalyzed by complexes bearing this ligand has been investigated. This ligand creates a remarkably general palladium catalyst for aryl halide amination and for Suzuki coupling. Turnovers of roughly 1000 were observed for aminations with unactivated aryl bromides or chlorides. In addition, complexes of this ligand catalyzed the formation of selected aryl ethers under mild conditions. The reactions encompassed electron-rich and electron-poor aryl bromides and chlorides. In the presence of catalysts containing this ligand, these aryl halides coupled with acyclic or cyclic secondary alkyl- and arylamines, with primary alkyl- and arylamines, and with aryl- and primary alkylboronic acids. These last couplings provide the first general procedure for reaction of terminal alkylboronic acids with aryl halides without toxic or expensive bases. The ligand not only generates highly active palladium catalysts, but it is air stable in solution and in the solid state. Palladium(0) complexes of this ligand are also air stable as a solid and react only slowly with oxygen in solution.
- Kataoka, Noriyasu,Shelby, Quinetta,Stambuli, James P.,Hartwig, John F.
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p. 5553 - 5566
(2007/10/03)
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- High turnover number and rapid, room-temperature amination of chloroarenes using saturated carbene ligands
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Pd(dba)2, 0.02-2 mol% Ligand 1, 0.08-2 mol% ArCl + NHRR′ → Ar-NRR′ NaO-t Bu, DME Ar = unactivated aryl, rt-100°C (71%-quant.) heteroaryl NHRR′ = 1° and 2° aryl; 2° acyclic and cyclic alkyl; imino A catalytic system for the mild amination of aryl chlorides is described. This system consists of a Pd(0) precursor and a dihydroimidazoline carbene ligand, which is generated in situ from its protonated tetrafluoroborate salt (2). Using this catalyst, aryl and heteroaryl chlorides react with secondary amines and anilines within hours at room temperature. Turnover numbers as high as 5000 are obtained at elevated temperatures for reaction of morpholine with an unactivated aryl chloride.
- Stauffer, Shaun R.,Lee, Sunwoo,Stambuli, James P.,Hauck, Sheila I.,Hartwig, John F.
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p. 1423 - 1426
(2007/10/03)
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