- C–N Cross-coupling Reactions of Amines with Aryl Halides Using Amide-Based Pincer Nickel(II) Catalyst
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Abstract: An approach to C–N cross-coupling reactions of aryl halides with amines in the presence of an amide-based pincer nickel(II) catalyst (2) is described. For 3?h reactions at 110?°C with 0.2?mol% catalyst, aryl bromides gave higher turnover numbers (TON) than the corresponding chlorides or iodides. Both primary and secondary amines could be used with the former giving higher TON. However, sterically hindered amines showed lower TON. In elucidating the mechanism of this nickel complex-catalyzed C–N cross coupling reaction it was found that the rate of reaction was unchanged in the presence of radical quenchers and a plausible Ni(I)–Ni(III) pathway is proposed. Graphic Abstract: [Figure not available: see fulltext.]Nickel pincer catalyst proved to be excellent catalyst for the C-N cross-coupling reaction with the high turnover number (TON) for 1° and 2° amines and different nonactivated aryl halides under optimum conditions.
- Albkuri, Yahya M.,RanguMagar, Ambar B.,Brandt, Andrew,Wayland, Hunter A.,Chhetri, Bijay P.,Parnell, Charlette M.,Szwedo, Peter,Parameswaran-Thankam, Anil,Ghosh, Anindya
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p. 1669 - 1678
(2019/12/27)
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- Practical and regioselective amination of arenes using alkyl amines
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The formation of carbon–nitrogen bonds for the preparation of aromatic amines is among the top five reactions carried out globally for the production of high-value materials, ranging from from bulk chemicals to pharmaceuticals and polymers. As a result of this ubiquity and diversity, methods for their preparation impact the full spectrum of chemical syntheses in academia and industry. In general, these molecules are assembled through the stepwise introduction of a reactivity handle in place of an aromatic C–H bond (that is, a nitro group, halogen or boronic acid) and a subsequent functionalization or cross-coupling. Here we show that aromatic amines can be constructed by direct reaction of arenes and alkyl amines using photocatalysis, without the need for pre-functionalization. The process enables the easy preparation of advanced building blocks, tolerates a broad range of functionalities, and multigram scale can be achieved via a batch-to-flow protocol. The merit of this strategy as a late-stage functionalization platform has been demonstrated by the modification of several drugs, agrochemicals, peptides, chiral catalysts, polymers and organometallic complexes.
- Ruffoni, Alessandro,Juliá, Fabio,Svejstrup, Thomas D.,McMillan, Alastair J.,Douglas, James J.,Leonori, Daniele
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p. 426 - 433
(2019/05/01)
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- PEt3-mediated deoxygenative C–N coupling of nitroarenes and boronic acids
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A method for the preparation of aryl- and heteroarylamine products by triethylphosphine-mediated deoxygenative coupling of nitroarenes and boronic acids is reported. This method provides access to an array of functionalized (hetero)arylamine products from readily available starting materials under the action of an inexpensive commercial reagent. The developed triethylphosphine-mediated transformation highlights the capability of organophosphorus compounds to carry out this useful deoxygenative transformation without the necessity of any transition metal additives.
- Nykaza, Trevor V.,Yang, Junyu,Radosevich, Alexander T.
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supporting information
p. 3248 - 3252
(2019/04/25)
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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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- Cu-Catalyzed Three-Component Carboamination of Alkenes
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Copper-catalyzed intermolecular carboamination of alkenes with α-halocarbonyls and amines is presented with 42 examples. Electron rich, electron poor, and internal styrenes, as well as α-olefins, are functionalized with α-halocarbonyls and aryl or aliphat
- Gockel, Samuel N.,Buchanan, Travis L.,Hull, Kami L.
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supporting information
p. 58 - 61
(2018/01/17)
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- Synthesis of Polyfunctional Secondary Amines by the Reaction of Functionalized Organomagnesium Reagents with Tertiary Nitroalkanes
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Addition of polyfunctionalized aryl, heteroaryl, and tertiary alkylmagnesium reagents to tertiary nitroalkanes at 25A"°C in tetrahydrofuran produces, after reductive workup with FeCl2 and NaBH4 in ethanol, the corresponding polyfunctional secondary amines in high yields.
- Dhayalan, Vasudevan,Knochel, Paul
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p. 3246 - 3256
(2015/10/19)
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- Synthesis of polyfunctional secondary amines by the addition of functionalized zinc reagents to nitrosoarenes
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Addition of functionalized aryl, heteroaryl or adamantyl zinc reagents to various nitroso-arenes in the presence of magnesium salts and LiCl in THF produces after a reductive work-up with FeCl2 and NaBH4 in ethanol the corresponding polyfunctional secondary amines in high yields. This journal is
- Dhayalan, Vasudevan,S?mann, Christoph,Knochel, Paul
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supporting information
p. 3239 - 3242
(2015/06/01)
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- Palladium-catalyzed amination of aryl sulfides with aliphatic amines
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Conditions for the palladium-NHC-catalyzed amination of aryl sulfides with aliphatic as well as aromatic amines were established. The KHMDS-mediated amination of heteroaryl sulfides could proceed without palladium. Based on the distinct difference in reactivity of C-Br and C-S bonds, a sequential amination of bromothioanisole can take place to install two different alkylamino groups onto the aromatic ring in one pot. A palladium-NHC precatalyst shows high efficiency for C-S bond cleavage for the amination of aryl sulfides with aliphatic amines or aromatic amines.
- Gao, Ke,Yorimitsu, Hideki,Osuka, Atsuhiro
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supporting information
p. 2678 - 2682
(2015/04/27)
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- Copper-catalyzed N- tert -butylation of aromatic amines under mild conditions using tert -butyl 2,2,2-trichloroacetimidate
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A variety of aromatic amines have been found to expediently undergo copper-catalyzed N-tert-butylation in the presence of tert-butyl 2,2,2-trichloroactimidate at room temperature. Georg Thieme Verlag Stuttgart New York.
- Cran, John W.,Vidhani, Dinesh V.,Krafft, Marie E.
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p. 1550 - 1554
(2014/07/08)
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- Ligand-free copper(i) oxide nanoparticle-catalysed amination of aryl halides in ionic liquids
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In the following, we present a simple and feasible methodology for a C-N coupling reaction using nanoscale Cu2O catalysts incorporated in n-Bu4POAc ionic liquid media. It is shown that a wide range of amines and aryl halides can be coupled selectively in high yields, without the use of ligands or additives (bases) and without precautions against water or air. All catalyses can be carried out with a nanoparticle catalyst loading as low as 5 mol%, based on the used precursor.
- Kessler, Michael T.,Robke, Silas,Sahler, Sebastian,Prechtl, Martin H. G.
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p. 102 - 108
(2014/01/06)
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- New phosphine-functionalized NHC ligands: Discovery of an effective catalyst for the room-temperature amination of aryl chlorides with primary and secondary amines
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We report convenient and high-yielding syntheses of new phosphine-functionalized dihydroimidazolium salts and demonstrate their utility as ligand precursors for Buchwald-Hartwig amination. Several examples of the general formula [1-Mes-3-{2-(PR2)phenyl}imidazolidin-2-ylium][BF 4] have been prepared, where phosphines of varying steric and electronic properties (R = Ph (9), Cy (10), 1-Ad (11)) are tethered by an o-phenylene group. The synthesis was not adaptable to N-aryl groups other than mesityl, giving unexpected phosphonium salt species instead. The synthesis was adapted to flexible benzyl-linked variants of the formula [1-Ar-3-{2-(PCy 2)benzyl}imidazolidin-2-ylium][BF4], which allowed more steric variation of the dihydroimidazolium N-aryl group (Ar = Mes (21), Dipp (22)). A preliminary study of these hybrid NHC/P ligands in Buchwald-Hartwig amination catalysis (in situ precatalyst formation) revealed 11 to be the most active of the series. Premixing the isolated free NHC ligand 1-Mes-3-{2-(PAd2)phenyl}imidazolidin-2-ylidene (23) with [Pd(cinnamyl)Cl]2 provided a highly active precatalyst that performed well at room temperature and 1 mol % catalyst loading. The system was shown to have an unprecedented ability to arylate both primary alkylamines (monoarylation) and secondary dialkylamines with aryl chlorides at room temperature. Electron-rich and -poor aryl and heteroaryl halides, as well as those featuring ortho substitution, were well tolerated, while substrates featuring both primary and secondary amine groups were selectively arylated at the NH2 position. Furthermore, a preliminary examination of performance in ammonia arylation and acetone α-arylation showed promising results, giving good conversion and high selectivity for monoarylation in both cases.
- Wheaton, Craig A.,Bow, John-Paul J.,Stradiotto, Mark
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p. 6148 - 6161
(2013/12/04)
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- Catalysts, Methods of Makting Catalysts, and Methods of Use
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Embodiments of the present disclosure provide for acyclic diaminocarbenes (ADCs) catalysts such as those shown in FIG. 1.1 and in the Examples, methods of making catalysts, methods of using catalysts, and the like. Catalyst of the present disclosure can b
- -
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Page/Page column 8
(2012/03/26)
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- Efficient catalytic aryl amination of bromoarenes using 3-iminophosphine palladium(II) chloride
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While pursuing the development of new hydroamination catalysts, a 3-iminophosphine palladium(II) chloride complex [(3IP)PdCl2] was synthesized that has subsequently proven to be an effective precatalyst for the aryl amination of bromoarenes. This (3IP)PdCl2 complex has been utilized in the catalytic aryl amination of both bromobenzene and bromopyridine derivatives, specifically yielding excellent activity in coupling reactions involving bromobenzene, 4-bromotoluene, and 2-bromopyridine. Using a standard set of catalytic conditions, many alkyl and aryl amines have been investigated as coupling partners in the aryl amination of bromoarenes. In general, secondary alkyl amines and ortho-substituted anilines proved to be the best substrates for this reaction, commonly giving quantitative conversion to products, while primary amines and other anilines gave only poor to moderate results. Catalytic screening data, product yields, and full characterization of isolated products are included.
- Samblanet, Danielle C.,Schmidt, Joseph A. R.
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p. 7 - 18,12
(2012/12/12)
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- A highly versatile catalyst system for the cross-coupling of aryl chlorides and Amines
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The syntheses of 2-(di-tertbutylphosphino)-N,N-dimethylaniline (L1, 71%) and 2-(di-1-adamantylphosphino)-N,N-dimethylaniline (L2, 74%), and their application in BuchwaldHartwig amination, are reported. In combination with [Pd(allyl)Cl]2 or [Pd(cinnamyl)Cl]2, these structurally simple and air-stable P,N ligands enable the cross-coupling of aryl and heteroaryl chlorides, including those bearing as substituents enolizable ketones, ethers, esters, carboxylic acids, phenols, alcohols, olefins, amides, and halogens, to a diverse range of amine and related substrates that includes primary alkyl- and arylamines, cyclic and acyclic secondary amines, N-H imines, hydrazones, lithium amide, and ammonia. In many cases, the reactions can be performed at low catalyst loadings (0.5-0.02 mol % Pd) with excellent functional group tolerance and chemoselectivity. Examples of cross-coupling reactions involving 1,4-bromochlorobenzene and iodobenzene are also reported. Under similar conditions, inferior catalytic performance was achieved when using Pd(OAc)2, PdCl2, [PdCl2(cod)] (cod = 1,5-cyclooctadiene), [PdCl 2(MeCN)2], or [Pd2(dba)3] (dba = dibenzylideneacetone) in combination with L1 or L2, or by use of [Pd(allyl)Cl]2 or [Pd(cinnamyl)Cl]2 with variants of L1 and L2 bearing less basic or less sterically demanding substituents on phosphorus or lacking an ortto-dimethylamino fragment. Given current limitations associated with established ligand classes with regard to maintaining high activity across the diverse possible range of C-N coupling applications, L1 and L2 represent unusually versatile ligand systems for the cross-coupling of aryl chlorides and amines
- Lundgren, Rylan J.,Sappong-Kumankumah, Antonia,Stradiotto, Mark
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supporting information; experimental part
p. 1983 - 1991
(2010/07/03)
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- Novel acyclic diaminocarbene ligands with increased steric demand and their application in gold catalysis
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Sterically demanding and conformationally stable N,N′- ditertiaryalkyl-N,N′-diphenyl acyclic diaminocarbenes (ADCs) were developed. Bulky ADC-Au catalysts not only showed competitive reactivities in hydroamination and enyne cyclization but also demonstrat
- Seo, Hwimin,Roberts, Benjamin P.,Abboud, Khalil A.,Merz Jr., Kenneth M.,Hong, Sukwon
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supporting information; experimental part
p. 4860 - 4863
(2011/02/22)
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- Efficient palladium-catalyzed amination of aryl chlorides using dicyclo-hexylamino[(2,6-dimethyl)morpholino]phenylphosphine as a PN2 ligand
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The palladium-catalyzed amination of aryl chlorides with various amines is accomplished using dicyclohexyl- amino[(2,6-dimethyl)morpholino]phenylphosphine as a bulky electron-rich monoaryl phosphine ligand. The optimized reaction conditions required the use of 1 mol% each of catalyst and ligand. Georg Thieme Verlag Stuttgart.
- Park, Song-Eun,Kang, Seung Beom,Jung, Kwang-Ju,Won, Ju-Eun,Lee, Sang-Gyeong,Yoon, Yong-Jin
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experimental part
p. 815 - 823
(2009/07/11)
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- Para-alkylation of aromatic primary amines
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A method is provided for producing primarily para alkyl aromatic amines by alkylating a primary aromatic amine with an olefin in the presence of an acid activated clay.
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Page/Page column 1-2
(2008/06/13)
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- Efficient palladium catalysts for the amination of aryl chlorides: A comparative study on the use of phosphium salts as precursors to bulky, electron-rich phosphines
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Alkyl-di-(1-adamantyl)phosphonium salts are practical ligand precursors for the palladium-catalyzed amination of aryl chlorides. In the presence of typically 0.5 mol% Pd(OAc)2 and 1 mol% of ligand precursor a variety of activated and deactivated aryl chlorides can be aminated in good to excellent yield (73-99%). Applying optimized conditions catalyst turnover numbers up to 10,000 have been achieved.
- Tewari, Amit,Hein, Martin,Zapf, Alexander,Beller, Matthias
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p. 9705 - 9709
(2007/10/03)
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- Ligand- and Base-Free Copper(II)-Catalyzed C-N Bond Formation: Cross-Coupling Reactions of Organoboron Compounds with Aliphatic Amines and Anilines
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(Equation presented) A ligandless and base-free Cu-catalyzed protocol for the cross-coupling of arylboronic acids and potassium aryltrifluoroborate salts with primary and secondary aliphatic amines and anilines is described. The process utilizes catalytic copper(II) acetate monohydrate and 4 A molecular sieves in dichloromethane at slightly elevated temperatures under an atmosphere of oxygen. A broad range of functional groups are tolerated on both of the cross-coupling partners.
- Quach, Tan D.,Batey, Robert A.
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p. 4397 - 4400
(2007/10/03)
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- Copper-catalyzed amination of aromatic halides with 2-N,N-dimethylaminoethanol as solvent
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A copper-catalyzed amination of aromatic halides under mild conditions using N,N-dimethylaminoethanol as solvent is described. We have studied this reaction in some detail varying the copper source, base, water content and other parameters including the scope of useful amine and aromatic halide structures. A variety of 4-halo-N,N-cycloalkylanilines and 2-N,N-cycloalkylaminothiophenes were synthesized for further elaboration into chromophores for optoelectronic applications.
- Lu, Zhikuan,Twieg, Robert J.,Huang, Songping D.
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p. 6289 - 6292
(2007/10/03)
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- Reductive activation of arenes: XIV.Effect of medium on the products ratio in the alkylation of nitrobenzene radical anion sodium salt
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The product of nitrobenzene reduction by 1 equiv of sodium reacted with tert-butyl iodide in liquid ammonia and its mixtures with tetrahydrofuran and hexamethylphosphoramide to afford a mixture of compounds alkylated either by the functional group (N-alkylation) or at the benzene ring (C-alkylation). The ratio of N-and C-alkylation products decreases in the solvents series NH3-THF (5.7) > NH3 (1.0) > NH3-HMPA (0.6).
- Selivanov,Shteingarts
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p. 1719 - 1722
(2007/10/03)
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- Synthesis and reactivity of pentavalent biphenyl-2,2′-ylenebismuth derivatives
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Phenylbiphenyl-2,2′-ylenebismuth diacetate reacted with nucleophiles under basic conditions to give modest to good yields of the C-phenylated substrates. Under copper catalysis, it reacted with hydroxy or amino groups to give the products of O- or N-phenylation. In both sets of reaction conditions, this reagent showed a reduced reactivity compared to the analogous triphenylbismuth diacetate reagent. It showed also a high regioselectivity as only the phenyl derivatives were detected and isolated. The Royal Society of Chemistry 2000.
- Fedorov, Alexey Yu.,Finet, Jean-Pierre
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p. 3775 - 3778
(2007/10/03)
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- Scope and Limitations of the Pd/BINAP-Catalyzed Amination of Aryl Bromides
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Mixtures of Pd2(dba)3 or Pd(OAc)2 and BINAP catalyze the cross-coupling of amines with a variety of aryl bromides. Primary amines are arylated in high yield, and certain classes of secondary amines are also effectively transformed. The process tolerates the presence of several functional groups including methyl and ethyl esters, enolizable ketones, and nitro groups provided that cesium carbonate is employed as the base. Most reactions proceed to completion with 0.5-1.0 mol % of the palladium catalyst; in some cases, catalyst levels as low as 0.05 mol % Pd may be employed. Reactions are considerably faster if Pd(OAc)2 is employed as the precatalyst, and the order in which reagents are added to the reaction has a substantial effect on reaction rate. It is likely that the catalytic process proceeds via bis(phosphine)palladium complexes as intermediates. These complexes are less prone to undergo undesirable side reactions which lead to diminished yields or catalyst deactivation than complexes of the corresponding monodentate triarylphosphines.
- Wolfe, John P.,Buchwald, Stephen L.
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p. 1144 - 1157
(2007/10/03)
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- The chemistry of pentavalent organobismuth reagents. Part 14. Recent advances in the copper-catalyzed phenylation of amines
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A reinvestigation of the copper-mediated phenylation of amines by Bi(V) reagents is reported. The influence of the ligands bound to bismuth and the basicity of the amines have been examined. These results, combined with our previous observations, led to the development of a new system for the quantitative phenylation of selected hindered aliphatic and aromatic amines.
- Arnauld, Thomas,Barton, Derek H.R.,Doris, Eric
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p. 4137 - 4144
(2007/10/03)
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- Preparation and solvolysis kinetics of trimethylsilyl N-alkyl-N-phenyl-carbamates
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Some trimethylsilyl esters of N-phenyl-N-alkyl- (methyl-, ethyl-, npropyl-, ipropyl-, nbutyl-, tbutyl-) carbamic acids were prepared by a novel method.Their solvolysis with isopropanol was studied.UV spectrophot
- Szalay, R.,Knausz, D.,Szakacs, L.,Ujszaszy, K.,Sohar, P.
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p. 267 - 272
(2007/10/02)
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- Reductive Activation of Arenes. X. Effect of the Cation and Crown-Ether Additions on the Direction of tert-Butylation of Products of One-Electron Reduction of Nitrobenzene by Alkali Metals in Liquid Ammonia
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Reaction of tert-butyl iodide with products of one-electron reduction of nitrobenzene by alkali metals (Li, Na, K, Rb, Cs) in liquid ammonia results in formation of compounds alkylated at the nitro group (N-alkylation) and the benzene ring (C-alkylation).The ratio of the N- and C-alkylated products (N/C) increases with increasing size of the alkali metal cation.Additions of crown ethers or sodium bromide and iodide, as well as variation of the concentration of the reduction product have almost no effect on the N/C value.Increased overall yield of the alkylation products and reduced N/C ratio were observed when the product of nitrobenzene reduction with potassium reacted with tert-butyl iodide in the presence of dicyclohexano-18-crown-6.
- Selivanov, B. A.,Shteingarts, V. D.
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p. 1276 - 1283
(2007/10/03)
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- REDUCTIVE ACTIVATION OF ARENES. VI. REACTION OF THE PRODUCT OF THE ONE-ELECTRON REDUCTION OF NITROBENZENE BY SODIUM IN LIQUID AMMONIA WITH ISOMERIC BUTYL IODIDES
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The reaction of the product of the reduction of nitrobenzene by one equivalent of sodium in liquid ammonia with n-butyl, sec-butyl, and isobutyl iodides leads to the corresponding N,O-dialkylphenylhydroxylamines as the major products through an SN2 mechanism.The analogous reaction with tert-butyl iodide gives approximately equal amounts of products of butylation in the benzene ring, namely, 4-tert-butylnitrobenzene and 4-tert-butylaniline, and at the nitro-group, namely, N-tert-butylaniline and N-tert-butylphenylhydroxylamine.The formation of these N-tert-butyl produ cts is probably the result of the transfer of an electron from the nitrobenzene radical-anion to the alkyl iodide and subsequent recombination of the tert-butyl radical with the nitrobenzene radical-anion.The increase in the fraction of tert-butylation at the nitro group in going from hexamethylphosphorotriamide or its mixture with tetrahydrofuran as the solvent to liquid nitrogen is probably a consequence of a greater role for interaction with the medium, which affects the distribution of the spin density in the nitrobenzene radical-anion or on the relative stability of the transition states responsible for the competing recombination pathways.
- Selivanov, V. A.,Shteingarts, V. D.
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p. 1654 - 1662
(2007/10/02)
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- Oxoiminium Ions for N-Demethylation: 1-Oxo-2,2,6,6,-tetramethylpiperidinium Chloride
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In an attempt to assess the synthetic utylity of oxoiminium ions as oxidizing agents and to delineate their reaction mechanisms, we reacted 1-oxo-2,2,6,6-tetramethylpiperidinium chloride (1) with several N,N-dialkylanilines.With N,N-dimethylaniline the only basic product was N-nethylaniline while N- methylformanilide was the only neutral product.The relative amounts of base and neutral product proved to be sensitive to the amount of water present in the reaction medium.With N-alkyl-N-methylanilines, the basic products were N-alkylanilines from exlusive loss of the N-methyl group.The neutral products were the N-alkylformanilides.The alkyl groups studied were ethyl, n-butyl, isopropyl, and benzyl.With N-tert-butyl-N-methylaniline, there was no observed reaction, and N,N-diethylaniline was found to be significantly less reactive than N,N-dimethylaniline.This study has shown that 1 is selective in N-demethylation of anilines in the presence of other alkyl groups either on the same nitrogen or on separate nitrogens.These results have been interpreted in terms of important steric interactions resulting from formation of an adduct en route to an intermediate iminium ion.
- Hunter, Duncan H.,Racok, Julie S.,Rey, Allan W.,Ponce, Yolanda Zea
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p. 1278 - 1281
(2007/10/02)
-
- RADICAL-ANIONS OF AROMATIC COMPOUNDS. VII. REACTION OF THE PRODUCTS FROM THE REDUCTION OF NITROBENZENE BY SODIUM WITH ISOPROPYL AND tert-BUTYL IODIDES
-
The reaction of the products from the reduction of nitrobenzene by one and two equivalents of sodium with isopropyl iodides leads to the formation of N,O-diisopropylphenylhydroxylamine, while the reaction with tert-butyl iodide leads to p-(tert-butyl)nitrobenzene.Such a change in the nature of the reaction product in the transition from the primary and secondary alkyl halides to the tertiary alkyl halides clearly results from a change in the SN2 mechanism to the SRN1 mechanism, involving transfer of an electron from the radical-anion or dianion of nitrobenzene to the alkyl halide.The formation of considerable amounts of azoxybenzene in the reaction with tert-butyl iodide shows that the dianion and, to a lesser degree, the radical-anion of nitrobenzene exhibit basic characteristics.
- Danilova, N. K.,Shteingarts, V. D.
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p. 701 - 708
(2007/10/02)
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- The Pyrolysis of N-Allyl Compounds: Free-radical and Retro-ene Mechanisms
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Flash vacuum pyrolysis of N-alkyl-N-allylanilines gives imines by free radical cleavage of the allyl group followed by loss of an atom (or group of atoms) from the α-carbon atom of the alkyl group.The corresponding N-propargyl derivatives also give imines on pyrolysis, but the mechanism is a concerted retro-ene process which may lead to different products from the corresponding N-allyl compound.N-Allyl-N,N-dialkylamines also decompose thermally by a retro-ene process
- Cadogan, J. I. G.,Hickson, Clare L.,McNab, Hamish
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p. 2247 - 2273
(2007/10/02)
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- Aromatic Substitution in the Gas Phase. Intramolecular Selectivity of the Reaction of Aniline with Charged Electrophiles
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The intramolecular selectivity of the electrophilic reactions of radiolytically formed C2H5+, i-C3H7+, t-C4H9+, (CH3)2F+, and CH3CO+ cations with aniline has been investigated in the gas phase at nearly atmospheric pressure.Under conditions of kinetic control of products, the reactivity of the N atom and of the aromatic ring is comparable, a mixture of ring- and N-substituted products being invariably formed in proportions that depend on the nature of the electrophile.The relative rate of N-substitution increases in the order: C2H5+ ca. i-C3H7++++.The positional selectivity of the gaseous electrophiles, except CH3CO+, is characterized by predominant ortho substitution.
- Attina, Marina,Cacace, Fulvio
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p. 1122 - 1126
(2007/10/02)
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- Nitrous Acid Deamination of 1,1-Disubstituted Aromatic Hydrazines
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The nitrous acid deamination of N-methyl-N-phenylhydrazine, 1,1-diphenylhydrazine, and 9-aminocarbazole gave as products N-methylaniline, diphenylamine, and carbazole, respectively.N-tert-Butyl-N-phenylhydrazine gave N-tert-butylaniline and phenyl azide as products.These reactions were carried out in methanol, n-butanol, and benzene with isoamyl nitrite-HBF4 and isoamyl nitrite-acetic acid as the deamination reagents.Nitrous oxide was produced in all reactions.This demonstrates that secondary amines are formed in two processes.It is proposed that the initially formed N-nitrosohydrazines can also give an N-diazonium ion.This species can decompose to give a nitrenium ion and nitrogen or phenyl azide and a carbonium ion.When the deamination of N-tert-butyl-N-phenylhydrazine was carried out in methanol, the carbonium ion fragment was trapped as the methyl ether.The formation of phenyl azide and methyl-tert-butyl ether is evidence for the existence of an N-diazonium ion.The products expected from a singlet nitrenium ion derived from N-tert-butyl-N-phenylhydrazine were prepared.No evidence was found for their formation.Evidence is presented that nitrogen-centered radicals are not formed.The results indicate that the nitrenium ions generated by deamination are different from similar species produced from N-chloroanilines.This difference appears to be related to the manner in which the positive charge develops.It is proposed that the decomposition of the N-diazonium ion generates a nitrenium ion in which the positive charge is localized on nitrogen and that this leads to an enhanced rate of spin inversion.The secondary amines observed are formed by hydrogen atom abstraction by a triplet nitrenium ion and, as previously observed, with the formation of nitrous oxide.
- Rosa, Michael De,Haberfield, Paul
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p. 2639 - 2643
(2007/10/02)
-
- Photochemical Reactions of Substituted Benzenes with Aliphatic Amines
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The products arising from the irradiation of diethylamine and t-butylamine with toluene, chlorobenzene, anisole, benzonitrile, benzyl fluoride, benzotrifluoride (α,α,α-trifluorotoluene), m-fluorobenzotrifluoride (α,α,α,m-tetrafluorotoluene), p-fluorotoluene, m-fluorotoluene, p-fluoroanisole, m-fluoroanisole, and 1,3-bis(trifluoromethyl)benzene, and of triethylamine with toluene, benzotrifluoride and 1,3-bis(trifluoromethyl)benzene, all at 254 nm, are described.Reaction pathways involving both substitution and 1,2- and 1,4-acyclic addition processes are observed and which predominates depends upon the arene substituent.The novel acyclic adduct, Me2C=CH-CH=CH-CH=NBut, is obtained from toluene and t-butylamine and, contrary to previous reports, chlorobenzene yields arene-amine 1:1 adducts as well as the amine α-substitution product (16); benzonitrile gives aniline derivatives with the primary and secondary amines.
- Gilbert, Andrew,Krestonosich, Stefan,Westover, David L.
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p. 295 - 302
(2007/10/02)
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- Exited State Substitution and Addition Reactions of Aryl Fluorides with Aliphatic Amines
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Fluorobenzene and the difluorobenzenes undergo photochemical reaction with t-butylamine and diethylamine to give both 1:1 adducts and substitution products but only the latter are formed from hexafluorobenzene and diethylamine.Both cine and 'normal' substitution products are observed from the difluoro-compounds and the mechanism to account for this is considered to involve a polar excited-state complex between the addends and an addition-elimination process rather than benzyne intermediates. 1,2-Acyclic amine photoadducts are produced from most systems but the corresponding 1,4-isomers are the major adducts from p-difluorobenzene and that from diethylamine is unique in undergoing thermal retro-addition to the starting materials rather than conversion into the aniline derivative.
- Gilbert, Andrew,Krestonosich, Stefan
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p. 1393 - 1399
(2007/10/02)
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- Novel N-Alkylation of Amines with Organocopper Reagents
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A mild and efficient method for the N-alkylation of amines is described, based on the oxidative coupling of lithium alkylcopper amide, which is derived from lithium dialkylcuprates and primary or secondary amines.The high chemospecificity of the method was demonstrated.
- Yamamoto, Hisashi,Maruoka, Keiji
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p. 2739 - 2740
(2007/10/02)
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