- 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
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supporting information
p. 7669 - 7674
(2021/03/08)
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- Tertiary butylation of aniline over nanosized zeolite beta catalyst
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In the current paper, we report nanosized zeolite beta to be a robust and potent catalyst for tertbutylation of aniline. Nanocrystals of beta zeolite having spherical morphology were prepared via a one-pot strategy that is based on vacuum-concentration coupled hydrothermal method. The catalyst could be used in the as-synthesized form, without any further modifications. In the presence of the as-prepared catalyst, liquid-phase tert-butylation of aniline using tert-butanol as alkylating agent proceeded successfully. Reaction parameters like duration of reaction, temperature, mole ratio of substrates and quantity of catalyst were optimized. Time-dependent data obtained was subjected to kinetic studies. Detailed studies on product selectivity were conducted. The catalyst could selectively direct the formation of C–C bonds and no N-alkylated products were detected. It also demonstrated good selectivity towards mono-substitution. The catalyst could be recovered by a simple work-up plan and could then be re-used. No appreciable loss in activity was detected in consecutive runs. Thus, the nanosized beta mediated route to introduce tert-butyl group on aniline ring can be an environment-friendly alternative to the use of homogeneous catalysts.
- Radhika,Selvin, Rosilda,Kakkar, Rita,Selva Roselin,Hsu, Hsiu-Ling
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p. 7960 - 7968
(2018/08/09)
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- Synthesis method of 4,4-diamino 3,3-di-tert-butyl diphenylmethane
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The invention aims at providing a synthesis method of 4,4-diamino 3,3-di-tert-butyl diphenylmethane. According to the process, o-tert-butyl aniline is used as raw materials to perform further a condensation reaction with formaldehyde under the effect of solid acid catalysts to obtain the 4,4-diamino 3,3-di-tert-butyl diphenylmethane. The reaction temperature is 90 to 150 DEG C; the reaction time is 1 to 8 hours. The o-tert-butyl aniline can be obtained through methyl tertiary butyl ether or tert-butyl alcohol alkylation reaction via aniline; the raw material cost is greatly reduced; the huge possibility is provided for the industrial application of the 4,4-diamino 3,3-di-tert-butyl diphenylmethane. The catalyst is montmorillonoid or kaolin with layered structures sold in the market. The catalyst can be cyclically used. High activity is realized on the synthesis of 4,4-diamino 3,3-di-tert-butyl diphenylmethane from the o-tert-butyl and the formaldehyde. The process belongs to a green environment-friendly and efficient synthesis process for the 4,4-diamino 3,3-di-tert-butyl diphenylmethane.
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Paragraph 0012; 0013; 0014
(2017/03/18)
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- Catalytic transfer reductive cleavage of azo compounds to amines using chitosan-supported formate and zinc
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A convenient method for the cleavage of azo derivatives to the corresponding amines using chitosan-supported formate as hydrogen donors in conjunction with zinc is described.
- Han,Yu,Xu,Song,Yan,Ma,Zhen
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- Rh2(II)-catalyzed intramolecular aliphatic C-H bond amination reactions using aryl azides as the N-atom source
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Rhodium(II) dicarboxylate complexes were discovered to catalyze the intramolecular amination of unactivated primary, secondary, or tertiary aliphatic C-H bonds using aryl azides as the N-atom precursor. While a strong electron-withdrawing group on the nitrogen atom is typically required to achieve this reaction, we found that both electron-rich and electron-poor aryl azides are efficient sources for the metal nitrene reactive intermediate.
- Nguyen, Quyen,Sun, Ke,Driver, Tom G.
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supporting information; experimental part
p. 7262 - 7265
(2012/06/16)
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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 novel naphthylmethyleneimino-type photocleavable protecting group for primary amines
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A novel naphthylmethyleneimino-type protecting group for aliphatic and aromatic primary amines including α-amino acids was devised and its introduction was accomplished in good to excellent yields. This type of protecting group was found to be cleanly removed photochemically to regenerate the primary amines in good to high yields, regardless of steric and electronic properties. Georg Thieme Verlag Stuttgart.
- Igarashi, Tetsutaro,Shimokawa, Masaru,Iwasaki, Miyuki,Nagata, Kensaku,Fujii, Masato,Sakurai, Tadamitsu
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p. 1436 - 1440
(2008/02/13)
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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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- 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.
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- 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.
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- Screw Sense Selective Polymerization of Achiral Isocyanides Catalysed by Optically Active Nickel(II) Complexes
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Poly(isocyanides), (RN=Cn, can be prepared from isocyanides, , by the catalytic action of nickel(II) compounds.The main chain of these polymers is a rigid helix.This helical conformation results from a restricted rotation around the single bonds that connect the main-chain carbon atoms.Polymerization of achiral isocyanides generally gives a racemic mixture of left- and right-handed helices, whereas polymerization of optically active isocyanides results in helices with an excess of one screw sense.We describe a procedure for obtaining poly(isocyanides) with predominantly one screw sense, starting from an achiral monomer.A catalyst is prepared by adding an optically active amine to a tetrakis(isocyanide)nickel(II) perchlorate complex.Polymerization of various achiral isocyanides with this catalist yields optically active polymers with an enantiomeric excess up to 83percent.
- Kamer, Paul C. J.,Nolte, Roeland J. M.,Drenth, Wiendelt
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p. 6818 - 6825
(2007/10/02)
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- Polar Effects in Free Radical Reactions. Homolytic Aromatic Amination by the Amino Radical Cation, +NH3: Reactivity and Selectivity
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Small amounts of Fe(II) salt initiate redox chains with hydroxyamino-O-sulfonic acid (HSA) and aromatic compounds leading to the amination of the aromatic ring.The positional and substrate selectivity with a variety of substituted benzenes show the important role of the electrophilic character of the radical +NH3.Hammett relationships with ? and ?+ are roughly observed.The lower sensitivity to polar effects of the radical +NH3 compared with (CH3)2+NH is explained by the different reaction enthalpies.The different positional selectivity obtained with anisole and the redox system +NH3OH/Ti(III) is discussed.
- Citterio, Attilio,Gentile, Anna,Minisci, Francesco,Navarrini, Valter,Serravalle, Marco,Ventura, Susanna
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p. 4479 - 4482
(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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- Chemical process
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Aromatic amines (e.g., aniline) are selectively alkylated in an ortho nuclear position by reaction with an olefin (e.g., ethylene) in the presence of an aluminum anilide catalyst. Hydrogen halides (e.g., HCl) are added to increase the reaction rate.
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