- Minimization of Back-Electron Transfer Enables the Elusive sp3 C?H Functionalization of Secondary Anilines
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Anilines are some of the most used class of substrates for application in photoinduced electron transfer. N,N-Dialkyl-derivatives enable radical generation α to the N-atom by oxidation followed by deprotonation. This approach is however elusive to monosubstituted anilines owing to fast back-electron transfer (BET). Here we demonstrate that BET can be minimised by using photoredox catalysis in the presence of an exogenous alkylamine. This approach synergistically aids aniline SET oxidation and then accelerates the following deprotonation. In this way, the generation of α-anilinoalkyl radicals is now possible and these species can be used in a general sense to achieve divergent sp3 C?H functionalization.
- Zhao, Huaibo,Leonori, Daniele
-
supporting information
p. 7669 - 7674
(2021/03/08)
-
- Mild deprotection of the: N-tert -butyloxycarbonyl (N -Boc) group using oxalyl chloride
-
We report a mild method for the selective deprotection of the N-Boc group from a structurally diverse set of compounds, encompassing aliphatic, aromatic, and heterocyclic substrates by using oxalyl chloride in methanol. The reactions take place under room temperature conditions for 1-4 h with yields up to 90percent. This mild procedure was applied to a hybrid, medicinally active compound FC1, which is a novel dual inhibitor of IDO1 and DNA Pol gamma. A broader mechanism involving the electrophilic character of oxalyl chloride is postulated for this deprotection strategy. This journal is
- Awuah, Samuel G.,George, Nathaniel,Ofori, Samuel,Parkin, Sean
-
p. 24017 - 24026
(2020/07/23)
-
- Telescoped Sequence of Exothermic and Endothermic Reactions in Multistep Flow Synthesis
-
A multistep sequential flow synthesis of isopropyl phenol is demonstrated, involving 4-step exothermic, endothermic, and temperature sensitive reactions such as nitration, reduction, diazotization, and high temperature hydrolysis. Nitration of cumene with fuming nitric acid produces 2- A nd 4-nitrocumene which are converted into respective cumidines by the hydrogenation using Pd/Ni catalyst in H-cube with gravity separation. Hydrolysis of in situ generated diazonium salts in the boiling acidic conditions is carried out using integration of flow and microwave-assisted synthesis. 58% of 4-isopropyl phenol was obtained. The sequential flow synthesis can be applied to synthesize other organic compounds involving this specific sequence of reactions.
- Sharma, Yachita,Nikam, Arun V.,Kulkarni, Amol A.
-
p. 170 - 176
(2019/02/01)
-
- NITROGEN-CONTAINING BIOPOLYMER-BASED CATALYSTS, THEIR PREPARATION AND USES IN HYDROGENATION PROCESSES, REDUCTIVE DEHALOGENATION AND OXIDATION
-
The present invention relates to a process for the preparation of a nitrogen containing biopolymer-based catalyst by pyrolysis of a metal complex with a nitrogen-containing biopolymer and to the nitrogen containing biopolymer-based catalysts obtainable by this process. In particular, the invention relates to a nitrogen containing biopolymer-based catalyst comprising metal particles and at least one nitrogen containing carbon layer. The invention also relates to the use of a nitrogen containing biopolymer-based catalyst in a hydrogenation process, preferably in a process for hydrogenation of nitroarenes, nitriles or imines; in a reductive dehalogenation process of C-X bonds, wherein X is CI, Br or I, preferably in a process for dehalogenation of organohalides or in a process for deuterium labelling of arenes via dehalogenation of organohalides; or in an oxidation process. Further, the invention relates to a metal complex with the nitrogen containing biopolymer, wherein the metal is a transition metal selected from the group consisting of manganese, ruthenium, cobalt, rhodium, nickel, palladium and platinum, preferably cobalt or nickel, and wherein the nitrogen containing biopolymer is selected from chitosan, chitin and a polyamino acid, preferably chitosan or chitin.
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Page/Page column 16; 31
(2018/07/29)
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- Selective Cross-Coupling of (Hetero)aryl Halides with Ammonia to Produce Primary Arylamines using Pd-NHC Complexes
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Herein we report the first example of (hetero)arylation of ammonia using a monoligated palladium-NHC complex. The new, rationally designed, precatalyst (DiMeIHeptCl)Pd(allyl)Cl featuring highly branched alkyl chains has been shown to be effective in selective aminations across a range of challenging substrates, including nitrogen-containing heterocycles and those featuring base-sensitive functionality. The less bulky Pd-PEPPSI-IPentCl precatalyst performs well for ortho-substituted aryl halides, giving monoarylated products in high yield with good selectivity.
- Lombardi, Christopher,Day, Jonathan,Chandrasoma, Nalin,Mitchell, David,Rodriguez, Michael J.,Farmer, Jennifer L.,Organ, Michael G.
-
supporting information
p. 251 - 254
(2017/04/26)
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- Biomass-Derived Catalysts for Selective Hydrogenation of Nitroarenes
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Development of catalytically active materials from biowaste represents an important aspect of sustainable chemical research. Three heterogeneous materials were synthesized from inexpensive biomass-based chitosan and abundant Co(OAc)2 using complexation followed by pyrolysis at various temperatures. These materials were applied in the catalytic hydrogenation of nitroarenes using molecular hydrogen. A variety of diversely functionalized nitroarenes including some pharmaceutically active compounds were converted into aromatic amines in high yields, with high selectivity, and with excellent functional group tolerance. This green protocol has also been implemented for the synthesis of a biologically important TRPC3 inhibitor.
- Sahoo, Basudev,Formenti, Dario,Topf, Christoph,Bachmann, Stephan,Scalone, Michelangelo,Junge, Kathrin,Beller, Matthias
-
p. 3035 - 3039
(2017/08/18)
-
- Co-based heterogeneous catalysts from well-defined Α-diimine complexes: Discussing the role of nitrogen
-
Ar-BIANs and related α-diimine Co complexes were wet impregnated onto Vulcan XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800?°C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110?°C, 50 bar H2) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen.
- Formenti, Dario,Ferretti, Francesco,Topf, Christoph,Surkus, Annette-Enrica,Pohl, Marga-Martina,Radnik, J?rg,Schneider, Matthias,Junge, Kathrin,Beller, Matthias,Ragaini, Fabio
-
-
- Electron-Transfer and Hydride-Transfer Pathways in the Stoltz–Grubbs Reducing System (KOtBu/Et3SiH)
-
Recent studies by Stoltz, Grubbs et al. have shown that triethylsilane and potassium tert-butoxide react to form a highly attractive and versatile system that shows (reversible) silylation of arenes and heteroarenes as well as reductive cleavage of C?O bonds in aryl ethers and C?S bonds in aryl thioethers. Their extensive mechanistic studies indicate a complex network of reactions with a number of possible intermediates and mechanisms, but their reactions likely feature silyl radicals undergoing addition reactions and SH2 reactions. This paper focuses on the same system, but through computational and experimental studies, reports complementary facets of its chemistry based on a) single-electron transfer (SET), and b) hydride delivery reactions to arenes.
- Smith, Andrew J.,Young, Allan,Rohrbach, Simon,O'Connor, Erin F.,Allison, Mark,Wang, Hong-Shuang,Poole, Darren L.,Tuttle, Tell,Murphy, John A.
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p. 13747 - 13751
(2017/10/12)
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- Reduction of nitroarenes using CO and H2O in the presence of a nanostructured cobalt oxide/Nitrogen-Doped Graphene (NGr) catalyst
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The most common route to anilines is based on the reduction of the corresponding nitroarenes. In general, hydrogen is preferred as reducing agent and numerous catalytic systems are known to achieve such transformations. Besides, the use of CO/H2O as hydrogen source offers interesting possibilities for reductions. Carbon monoxide is a cheap and abundant chemical used on industrial scale for a variety of transformations. Although the reduction of nitroarenes with CO/H2O is known in the presence of noble-metal catalysts, earth-abundant inexpensive catalysts showing high selectivity have not yet been developed. In this respect, herein we present the use of a heterogeneous cobalt oxide catalyst (Co3O4/NGr@C), which is modified by nitrogen-doped graphene layers. Using this non-noble metal catalyst nitroarenes are reduced in high yields and good chemoselectivities.
- Westerhaus, Felix A.,Sorribes, Ivn,Wienh?fer, Gerrit,Junge, Kathrin,Beller, Matthias
-
supporting information
p. 313 - 317
(2015/03/05)
-
- USE OF THERMALLY-TREATED SUPPORTED COBALT CATALYSTS COMPRISING A POLYCYCLIC AROMATIC STRUCTURE CONSISTING OF NITROGEN LIGANDS FOR HYROGENATING AROMATIC NITRO COMPOUNDS
-
The invention relates to the use of thermally-treated supported cobalt catalysts for hydrogenating aromatic nitro compounds, the cobalt catalysts having been prepared by in situ immobilization of a cobalt-amine complex on an inorganic porous support and subsequent pyrolysis, and, in the cobalt-amine complex used, cobalt being present bonded to an aromatic or heterocyclic nitrogen ligand L, the nitrogen ligand being selected so as to form a polyaromatic structure with the cobalt atom.
- -
-
Paragraph 0031; 0032
(2015/11/16)
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- The ortho effect on the acidic and alkaline hydrolysis of substituted formanilides
-
The kinetics of formanilides hydrolysis were determined under first-order conditions in hydrochloric acid (0.01-8 M, 20-60°C) and in hydroxide solutions (0.01-3 M, 25 and 40°C). Under acidic conditions, second-order specific acid catalytic constants were used to construct Hammett plots. The ortho effect was analyzed using the Fujita-Nishioka method. In alkaline solutions, hydrolysis displayed both first- and second-order dependence in the hydroxide concentration. The specific base catalytic constants were used to construct Hammett plots. Ortho effects were evaluated for the first-order dependence on the hydroxide concentration. Formanilide hydrolyzes in acidic solutions by specific acid catalysis, and the kinetic study results were consistent with the AAC2 mechanism. Ortho substitution led to a decrease in the rates of reaction due to steric inhibition of resonance, retardation due to steric bulk, and through space interactions. The primary hydrolytic pathway in alkaline solutions was consistent with a modified BAC2 mechanism. The Hammett plots for hydrolysis of meta- and para-substituted formanilides in 0.10 M sodium hydroxide solutions did not show substituent effects; however, ortho substitution led to a decrease in rate constants proportional to the steric bulk of the substituent.
- Desai, Salil Dileep,Kirsch, Lee E.
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p. 471 - 488
(2015/06/30)
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- Transition-metal-free access to primary anilines from boronic acids and a common +NH2 equivalent
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Diversely substituted anilines are prepared by treatment of functionalized arylboronic acids with a common, inexpensive source of electrophilic nitrogen (H2N-OSO3H, HSA) under basic aqueous conditions. Electron-rich substrates are found to be the most reactive by this method. However, even moderately electron-poor substrates are well tolerated under the room temperature conditions. Sterically hindered substrates appear to be equally effective compared to unhindered ones. Highly electron-deficient substrates afford product in very low yields at room temperature, but moderate to good yields are obtained at refluxing temperatures. Our method is also amenable to electrophilic amination of several common boronic acid derivatives (e.g., pinacol esters). We demonstrate that it can be combined with metal-halogen exchange reactions or a variety of directed ortho metalation protocols in a "one-pot" sequence for the synthesis of aromatic amines with unique substitution patterns. DFT studies, in combination with experimental results, suggest that the reaction occurs via base-mediated activation of HSA, followed by 1,2 aryl B-N migration. This mode of activation appears to be critical for the success of the reaction and allows, for the first time, a general, electrophilic amination of boronic acids at ambient temperature.
- Voth, Samantha,Hollett, Joshua W.,Mccubbin, J. Adam
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p. 2545 - 2553
(2015/03/18)
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- Heterogenized cobalt oxide catalysts for nitroarene reduction by pyrolysis of molecularly defined complexes
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Molecularly well-defined homogeneous catalysts are known for a wide variety of chemical transformations. The effect of small changes in molecular structure can be studied in detail and used to optimize many processes. However, many industrial processes require heterogeneous catalysts because of their stability, ease of separation and recyclability, but these are more difficult to control on a molecular level. Here, we describe the conversion of homogeneous cobalt complexes into heterogeneous cobalt oxide catalysts via immobilization and pyrolysis on activated carbon. The catalysts thus produced are useful for the industrially important reduction of nitroarenes to anilines. The ligand indirectly controls the selectivity and activity of the recyclable catalyst and catalyst optimization can be performed at the level of the solution-phase precursor before conversion into the active heterogeneous catalyst.
- Westerhaus, Felix A.,Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Pohl, Marga-Martina,Radnik, Joerg,Surkus, Annette-Enrica,Rabeah, Jabor,Junge, Kathrin,Junge, Henrik,Nielsen, Martin,Brueckner, Angelika,Beller, Matthias
-
p. 537 - 543
(2013/07/19)
-
- Hydrogenation of nitroarenes using defined iron-phosphine catalysts
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A novel iron-catalyzed hydrogenation of nitroarenes to the corresponding amines is reported. An in situ combination of Fe(BF4) 2·6H2O and phosphine allows for highly selective hydrogenation of a broad range of aromatic and nitroarenes tolerating different functional groups.
- Wienhoefer, Gerrit,Baseda-Krueger, Mario,Ziebart, Carolin,Westerhaus, Felix A.,Baumann, Wolfgang,Jackstell, Ralf,Junge, Kathrin,Beller, Matthias
-
supporting information
p. 9089 - 9091
(2013/09/24)
-
- Gold nanoparticles assisted formation of cobalt species for intermolecular hydroaminomethylation and intramolecular cyclocarbonylation of olefins
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The intermolecular hydroaminomethylation and the intramolecular cyclocarbonylation efficiently proceeded on cobalt oxide supported gold nanoparticles. The intermolecular reaction employing terminal olefins and N-isopropylaniline afforded hydroaminomethylated products as a mixture of regioisomers via a common reaction path consisting of hydroformylation, imine formation, and hydrogenation. In contrast, indolinone derivatives were exclusively obtained in the case of 2-alkenylanilines based on the intramolecular cyclocarbonylation mechanism. Both of these reactions were catalyzed by cobalt species derived from cobalt oxide. The active cobalt species were formed via reduction of the oxide support promoted by deposited gold nanoparticles. Characterization of the catalysts before and after the reaction was also performed.
- Liu, Xiaohao,Hamasaki, Akiyuki,Yamane, Yoshihiro,Aikawa, Shohei,Ishida, Tamao,Haruta, Masatake,Tokunaga, Makoto
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p. 3000 - 3006
(2013/11/06)
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- Elusive metal-free primary amination of arylboronic acids: Synthetic studies and mechanism by density functional theory
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Herein, we disclose the first metal-free synthesis of primary aromatic amines from arylboronic acids, a reaction that has eluded synthetic chemists for decades. This remarkable transformation affords structurally diverse primary arylamines in good chemical yields, including a variety of halogenated primary anilines that often cannot be prepared via transition-metal-catalyzed amination. The reaction is operationally simple, requires only a slight excess of aminating agent, proceeds under neutral or basic conditions, and, importantly, can be scaled up to provide multigram quantities of primary anilines. Density functional calculations reveal that the most likely mechanism involves a facile 1,2-aryl migration and that the presence of an ortho nitro group in the aminating agent plays a critical role in lowering the free energy barrier of the 1,2-aryl migration step.
- Zhu, Chen,Li, Gongqiang,Ess, Daniel H.,Falck, John R.,Kürti, László
-
supporting information
p. 18253 - 18256
(2013/01/15)
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- Highly selective amination of o-and p-alkyl phenols over Pd/Al 2O3-BaO
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A series of Pd-based catalysts were prepared and examined for the amination of 2,6-dimethylphenol in a fixedbed reactor. The best results were obtained for Pd/Al2O3-BaO with a conversion of 99.89% and a selectivity of 91.16%. These catalysts were characterized using BET, XRD, XPS, TEM and NH3-TPD. Doped BaO not only improved the dispersion of the Pd particles but also decreased the acidity of the catalyst, which remarkably enhanced the selectivity and stability of the catalyst. The generality of Pd/Al 2O3-BaO for this kind of reaction was demonstrated by catalytic aminations of o- and p-alkyl phenols.
- Ma, Jianchao,Wang, Huabang,Sun, Meng,Yang, Fan,Wu, Zhiwei,Wang, Donghua,Chen, Ligong
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experimental part
p. 387 - 392
(2012/05/04)
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- A convenient and general ruthenium-catalyzed transfer hydrogenation of nitro- and azobenzenes
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An easily accessible in situ catalyst composed of [{RuCl 2(p-cymene)}2] and terpyridine has been developed for the selective transfer hydrogenation of aromatic nitro and azo compounds. The procedure is general and the selectivity of the catalyst has been demonstrated by applying a series of structurally diverse nitro and azo compounds (see scheme).
- Jagadeesh, Rajenahally V.,Wienhoefer, Gerrit,Westerhaus, Felix A.,Surkus, Annette-Enrica,Junge, Henrik,Junge, Kathrin,Beller, Matthias
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experimental part
p. 14375 - 14379
(2012/01/14)
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- Palladium-catalyzed coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates: A general method for the preparation of primary arylamines
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We report that the complex generated from Pd[P(o-tol)3] 2 and the alkylbisphosphine CyPF-t-Bu is a highly active and selective catalyst for the coupling of ammonia with aryl chlorides, bromides, iodides, and sulfonates. The couplings of ammonia with this catalyst conducted with a solution of ammonia in dioxane form primary arylamines from a variety of aryl electrophiles in high yields. Catalyst loadings as low as 0.1 mol % were sufficient for reactions of many aryl chlorides and bromides. In the presence of this catalyst, aryl sulfonates also coupled with ammonia for the first time in high yields. A comparison of reactions in the presence of this catalyst versus those in the presence of existing copper and palladium systems revealed a complementary, if not broader, substrate scope. The utility of this method to generate amides, imides, and carbamates is illustrated by a one-pot synthesis of a small library of these carbonyl compounds from aryl bromides and chlorides, ammonia, and acid chlorides or anhydrides. Mechanistic studies show that reactions conducted with the combination of Pd[P(o-tol)3]2 and CyPF-t-Bu as catalyst occur with faster rates and higher yields than those conducted with CyPF-t-Bu and palladiun(II) as catalyst precursors because of the low concentration of active catalyst that is generated from the combination of palladium(II), ammonia, and base.
- Vo, Giang D.,Hartwig, John F.
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supporting information; experimental part
p. 11049 - 11061
(2009/12/05)
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- Efficient copper-catalyzed coupling of aryl chlorides, bromides and iodides with aqueous ammonia
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The copper(i)-catalyzed synthesis of a range of primary anilines from electron-rich and electron-deficient aryl halides including aryl chlorides has been achieved with aqueous ammonia, avoiding the need for inert atmosphere, expensive catalysts and ligands, anhydrous solvents, and additional base or other additives. The Royal Society of Chemistry 2009.
- Xu, Hanhui,Wolf, Christian
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supporting information; experimental part
p. 3035 - 3037
(2009/12/01)
-
- Rhodium(I)-catalyzed hydroaminomethylation of 2-isopropenylanilines as a novel route to 1,2,3,4-tetrahydroquinolines
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A new atom economical approach for the preparation of 1,2,3,4- tetrahydroquinolines can be achieved by means of the intramolecular hydroaminomethylation of 2-isopropenylanilines, mediated by an ionic diamino rhodium catalyst that does not require phosphine - this reaction is highly chemo- and regioselective, and it occurs in good isolated yields. The Royal Society of Chemistry.
- Vieira, Tiago O.,Alper, Howard
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p. 2710 - 2711
(2008/02/08)
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- PROCESS FOR THE SYNTHESIS OF ARYLAMINES FROM THE REACTION OF AN AROMATIC COMPOUND WITH AMMONIA OR A METAL AMIDE
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A catalytic process for the synthesis of aromatic primary amines, reagent compositions for effecting the process, and transition metal complexes useful in the process, are provided.
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Page/Page column 44; 45; 47
(2008/06/13)
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- Palladium-catalyzed coupling of ammonia and lithium amide with aryl halides
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A mild, palladium-catalyzed coupling of aryl halides with ammonia or lithium amide to form primary arylamines as the major product is described. These reactions occurred with excellent selectivity for formation of the primary arylamine over formation of the diarylamine (9.5:1 to over 50:1 ratios of arylamine to diarylamine). In addition, the first organopalladium complex with a terminal -NH2 ligand has been isolated. This complex reductively eliminates to form arylamines. Copyright
- Shen, Qilong,Hartwig, John F.
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p. 10028 - 10029
(2007/10/03)
-
- New ammonia equivalents for the Pd-catalyzed amination of aryl halides.
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[reaction: see text]. LiN(SiMe3)2, Ph3SiNH2, and LiNH2 can be be used as ammonia equivalents for the Pd-catalyzed coupling of aryl halides. Using these amine derivatives, simple anilines, including ortho-substituted ones, as well as di- and triarylamines can be readily prepared.
- Huang,Buchwald
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p. 3417 - 3419
(2007/10/03)
-
- Alkylation of aniline over base zeolites
-
Vapour phase alkylation of aniline with 2-propanol over Li, Na, K, Ca, Sr and Ba ion exchanged zeolites at atmospheric pressure gives N-alkylated and C-alkylated anilines. The N-alkylation selectivity increases with increase in basicity of the zeolite. The major product is the ortho-isomer. The effect of the basic nature of catalyst on the conversion and product selectivity has been evaluated. Co-existence of the acidic and basic sites in the alkali cation exchanged zeolites enhances the N-alkylation rather than the ring alkylation.
- Pillai
-
p. 490 - 491
(2007/10/03)
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- Isomerisation of N-isopropylaniline and N-n-propylaniline over zeolites
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Reactions of N-isopropylaniline and N-n-propylaniline over, Ce, H and Na forms of ZSM-5 and Y type zeolites at 200-400° have been investigated. Both the secondary amines isomerised on zeolites to produce o-isopropylaniline and p-isopropylaniline through SN1 mechanism and also dealkylated to give aniline and propene. The ortho-isomer is the major C-alkylated product. Effects of temperature and flow rate on activity and selectivity have been studied.
- Pillai
-
p. 157 - 158
(2007/10/03)
-
- Synthesis of functionalized carbamates through a palladium-catalyzed reductive carbonylation of substituted nitrobenzenes
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The palladium-catalyzed reductive carbonylation of ortho and para-substituted nitrobenzenes has proven to be an attractive route for the synthesis of functionalized carbamates. For the Pd(1,10-phenanthroline)2(triilate}2 catalyst system, the scope of the reaction has been studied. Substrates with electron-donating substituents at the para position were found to decrease the catalytic activity, most probably as a result of their relatively low oxidizing capacity. The selectivity towards the desired carbamate, however, was increased for these substrates. Under the influence of electron-withdrawing substituents the azoxybenzene and azobenzene derivatives became important side products. Introduction of large steric hindrance at the ortho position of the nitro substrates gave rise to an interesting side reaction, viz. methoxylation of the aromatic ring. The methoxylation reaction appeared to occur on an intermediate species in the catalytic cycle. Several functionalities have shown to be resistant to the reaction conditions required for the conversion of the nitro group. Especially with 4-nitrobenzoic acid, an extremely high activity and selectivity was found, thus yielding a very convenient synthesis for N-protected amines containing carboxylic acid functions. VCH Verlagsgesellschaft mbH.
- Wchman, Petra,Borst, Leo,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
-
-
- Direct Aromatic Amination by Azides: Reactions of Hydrazoic Acid and Butyl Azides with Aromatic Compounds in the Presence of Both Trifluoromethanesulfonic Acid and Trifluoroacetic Acid
-
Reactions of hydrazoic acid with aromatic compounds in the presence of both trifluoromethanesulfonic acid (TFSA) and trifluoroacetic acid (TFA) efficiently gave primary arylamines without diamine contaminants.The reactions provide mainly the ortho- and para-monoamines wven for readily oxidised aromatic compounds such as cumene, mesitylene, durene, isodurene and anisole.The mechanistic investigation demonstrates that the reactions proceed via a concerted process involving both arene attack on a conjugate acid of the azide and elimination of N2 from the conjugate acid.The reaction of butyl azide with benzene and mesitylene in the presence of both TFSA and TFA produced N-butylarylamines in low yields together with high yields of butanal via a butylnitrenium ion intermediate; a similar reaction with tert-butyl azide gave no tert-butylarylamines.
- Takeuchi, Hiroshi,Adachi, Taki,Nishiguchi, Hideaki,Itou, Katsutaka,Koyama, Kikuhiko
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p. 867 - 870
(2007/10/02)
-
- Alkylation of aniline by 2-propanol over zeolites
-
The reaction of aniline with 2-propanol over Y and ZSM-5 zeolites in the vapour phase have been studied.N-alkylation selectively decreases as contact time/temperature is increased.The main C-alkyl product is the ortho-isomer.
- Pillai, R B C,Pillai, C N
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p. 592 - 594
(2007/10/02)
-
- NiCl2(dppe)-Catalyzed Geminal Dialkylation of Dithioacetals and Trimethylation of Ortho Thioesters
-
NiCl2(dppe)-catalyzed cross-coupling of cinnamaldehyde dithioacetals gave the corresponding geminal dimethylation products in excellent yields.Allylic ortho thioesters afforded regioselectively the corresponding trimethylation products.The reaction may occur via an 18-electron ?-allyl intermediate, which undergoes facile reductive elimination to afford the geminal dimethylation product.Benzylic dithioacetals having an ortho amino group gave 2-isopropylanilines exclusively.The reaction of benzylic dithioacetals with EtMgBr under the same conditions yielded geminal diethylation products.
- Tzeng, Yih-Ling,Yang, Ping-Fan,Mei, Nai-Wen,Yuan, Tien-Min,Yu, Chun-Chi,Luh, Tien-Yau
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p. 5289 - 5293
(2007/10/02)
-
- Para-bromination of ortho-alkyl anilines
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A process of selectively preparing p-bromo-o-alkylanilines (e.g. 4-bromo-2-methylaniline) by reacting o-alkylanilines (e.g., 2-methylaniline) with unadsorbed bromine in a solvent selected from the group consisting of an inert di- tri- or tetrahaloaliphatic hydrocarbon (e.g., dichloromethane and dibromomethane), an alkyl nitrile (e.g., acetonitrile) and mixtures thereof.
- -
-
-
- New diamines and a process for their production
-
New aminoalkyl anilines having the formula: STR1 wherein k is 0 or 1; QNH2 is a residue of formula STR2 which is situated in one of the positions of the benzene ring ortho or para to the amino group and wherein n is an integer from 1 to 15, R1 is C1 -C8 alkyl, R2 is C1 -C4 alkyl or R1 and R2, together with the carbon atom to which they are attached, form a C5 -C8 cycloalkylene residue, R3 is H or C1 -C6 alkyl, C3 -C8 cycloalkyl, or C6 -C10 aryl; and R4 and R5 are H or C1 -C4 alkyl; as well as the corresponding salts of compounds of formula I with organic or inorganic acids and metal salt complexes; process for their production; and their use as intermediates for polyamides.
- -
-
-
- Intramolecular Selectivity of the Alkylation of Substituted Anilines by Gaseous Cations
-
The intramolecular selectivity of the electrophilic reactions of Et(1+), i-Pr(1+), and Me2F(1+) cations with substituted anilines, including m-toluidine, m-anisidine, and m- and p-fluoroaniline, has been investigated in the dilute gas state at pressures ranging from 100 to 720 torr by a radiolytic technique, complemented by chemical ionization mass spectrometry.The results indicate an appreciable kinetic bias for the nitrogen atom, leading to predominant N-methylation by Me2F(1+).The reactivity of the carbenium ions is complicated by the simultaneous occurrence of proton transfer, in particular to the NH2 group, which increases the relative extent of ring alkylation.The positional selectivity is characterized, aside from the usual orienting effects of the substituents, by the enchanced reactivity of the ring positions ortho to an n-type substituent, irrespective of its activating or deactivating properties.The effect is traced to the preliminary formation of an electrostatic adduct between the aniline and the gaseous electrophile.
- Attina, Marina,Cacace, Fulvio,de Petris, Giulia
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p. 1556 - 1561
(2007/10/02)
-
- 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)
-
- Selectivity in the Hydrogenation of 6- and 8-Substituted-quinolines
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Quinoline (1) and the 6- or 8-substituted-quinolines (2)-(14) (R = Me, Pri, But, Ph, OMe, OH, CF3, or F) were hydrogenated catalytically on platinum under either weakly basic (solvent MeOH) or strongly acidic (solvent CF3CO2H) conditions.In methanol the only product was the corresponding 1,2,3,4-tetrahydro-compound.In trifluoroacetic acid, compounds hydrogenated in the benzene ring were isolated as major products; both electron-withdrawing and electron-donating substituents at C-6 or C-8 cause (sometimes drastic) reduction in yield.The products were characterized by their 1H and 13C n.m.r. spectra.
- Hoenel, Michael,Vierhapper, Friedrich W.
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p. 1933 - 1939
(2007/10/02)
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