- Selective Carbon-Carbon Bond Amination with Redox-Active Aminating Reagents: A Direct Approach to Anilines?
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Amines are among the most fundamental motifs in chemical synthesis, and the introduction of amine building blocks via selective C—C bond cleavage allows the construction of nitrogen compounds from simple hydrocarbons through direct skeleton modification. Herein, we report a novel method for the preparation of anilines from alkylarenes via Schmidt-type rearrangement using redox-active amination reagents, which are easily prepared from hydroxylamine. Primary amines and secondary amines were prepared from corresponding alkylarenes or benzyl alcohols under mild conditions. Good compatibility and valuable applications of the transformation were also displayed.
- Qiu, Xu,Wang, Yachong,Su, Lingyu,Jin, Rui,Song, Song,Qin, Qixue,Li, Junhua,Zong, Baoning,Jiao, Ning
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supporting information
p. 3011 - 3016
(2021/09/13)
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- Method for synthesizing aromatic ketone by catalytic oxidation of aromatic benzylic secondary C-H bonds through metalloporphyrin (by machine translation)
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A method for synthesizing aromatic ketone by catalytic oxidation of aromatic benzylic secondary C-H bonds through metalloporphyrin, the method comprising: (1 ×10) preparing metalloporphyrin-4 % - 1%, Mol / mol are dispersed in the aromatic hydrocarbon, the reaction system is sealed, the temperature is raised to 80 - 150 °C by stirring, the oxidant is introduced to 0.20 - 2.0 mpa, the set temperature and pressure are maintained, ?datdatdate? is stirred 3.0-24 . 0h, and the reaction liquid is subjected to post-treatment to obtain the product aromatic ketone compound. The method has the advantages of low reaction temperature, low catalyst consumption, high selectivity of the aromatic ketone compound, low peroxide content and high production safety factor, and has the potential of overcoming the defects of high reaction temperature, low corrosive solvent and auxiliary agent in the catalytic oxidation process of the aromatic benzylic secondary C-H bonds in the industry. The method is efficient, feasible and safe. (by machine translation)
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Paragraph 0082-0083
(2020/09/20)
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- Pyridine mediated transition-metal-free direct alkylation of anilines using alcohols: via borrowing hydrogen conditions
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Herein, we report pyridine and other similar azaaromatics as efficient biomimetic hydrogen shuttles for a transition-metal-free direct N-alkylation of aryl and heteroaryl amines using a variety of benzylic and straight chain alcohols. Mechanistic studies including deuterium labeling and the isolation of dihydro-intermediates of the benzannulated pyridine confirmed the role of pyridine and a borrowing hydrogen process operating in these reactions. In addition, we have extended this methodology for the development of dehydrogenative synthesis of quinolines and indoles, as well as the transfer hydrogenation of ketones. This journal is
- Pothikumar, Rajagopal,Bhat, Venugopal T,Namitharan, Kayambu
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supporting information
p. 13607 - 13610
(2020/11/17)
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- Transfer Hydrogenation of Ketones and Imines with Methanol under Base-Free Conditions Catalyzed by an Anionic Metal-Ligand Bifunctional Iridium Catalyst
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An anionic iridium complex [Cp*Ir(2,2′-bpyO)(OH)][Na] was found to be a general and highly efficient catalyst for transfer hydrogenation of ketones and imines with methanol under base-free conditions. Readily reducible or labile substituents, such as nitro, cyano, and ester groups, were tolerated under present reaction conditions. Notably, this study exhibits the unique potential of anionic metal-ligand bifunctional iridium catalysts for transfer hydrogenation with methanol as a hydrogen source.
- Han, Xingyou,Li, Feng,Liu, Peng,Wang, Rongzhou,Xu, Jing
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p. 2242 - 2249
(2020/03/13)
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- Method for synthesizing secondary alcohol
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The invention discloses a method for synthesizing secondary alcohol, which utilizes transition metal catalysis and uses isopropanol as a hydrogen source to synthesize the secondary alcohol. The reaction not only uses inexpensive and environmentally friendly isopropanol as the hydrogen source and a solvent, but also has the advantages of high yield, environmental protection, and the like, and therefore the reaction has broad development prospects.
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Paragraph 0040; 0041; 0042; 0043
(2019/03/15)
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- Mild palladium-catalysed highly efficient hydrogenation of CN, C-NO2, and CO bonds using H2 of 1 atm in H2O
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Here we present the first example of a mild and high-efficiency protocol enabling a process in water using 1 atm of H2 for the efficient and selective hydrogenation of nitriles, nitro compounds, ketones, and aldehydes to yield primary amines and alcohols with satisfactory yields of up to >99%. Several palladium-based nanoparticle catalysts were prepared from K2PdCl4 and ligands, and one of them was found to be the best and most suitable for the hydrogenation of CN, C-NO2, and CO bonds. In addition, the catalyst Pd-NPs can be easily recycled and reused without losing their activity and selectivity. A plausible mechanism for the hydrogenation of a CN bond was also proposed, representing the first example that possesses great potential for sustainable industrial purposes.
- Liu, Yaxu,He, Shaopo,Quan, Ziyi,Cai, Huizhuo,Zhao, Yang,Wang, Bo
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supporting information
p. 830 - 838
(2019/02/27)
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- Half-sandwich Ru (II) complexes containing (N, O) Schiff base ligands: Catalysts for base-free transfer hydrogenation of ketones
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Two new half-sandwich Ru (II)(p-cymene) complexes (1 and 2) containing dopamine-based (N, O) Schiff base ligands (L1H and L2H) were synthesized and characterized by FT-IR, UV–Visible and 1H & 13C NMR spectral techniques, and elemental analyses. The spectroscopic and analytical data revealed monobasic bidentate coordination of the ligands with Ru ion. The molecular structures of L1H, L2H and 2 were further confirmed by single crystal X-ray diffraction study. Complexes 1 and 2?have been employed as catalysts in the transfer hydrogenation of ketones using 2-propanol as a hydrogen source at 85?°C under base-free condition. Good to the excellent yield of secondary alcohols, gram scale synthesis, and high TON and TOF made this catalytic system interesting.
- Satheesh,Sathish Kumar, Pushpanathan N.,Kumara, P. Raghavendra,Karvembu, Ramasamy,Hosamani, Amar,Nethaji
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- FLP-Catalyzed Transfer Hydrogenation of Silyl Enol Ethers
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Herein we report the first catalytic transfer hydrogenation of silyl enol ethers. This metal free approach employs tris(pentafluorophenyl)borane and 2,2,6,6-tetramethylpiperidine (TMP) as a commercially available FLP catalyst system and naturally occurring γ-terpinene as a dihydrogen surrogate. A variety of silyl enol ethers undergo efficient hydrogenation, with the reduced products isolated in excellent yields (29 examples, 82 % average yield).
- Khan, Imtiaz,Reed-Berendt, Benjamin G.,Melen, Rebecca L.,Morrill, Louis C.
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p. 12356 - 12359
(2018/09/18)
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- Transformation of Alkynes into Chiral Alcohols via TfOH-Catalyzed Hydration and Ru-Catalyzed Tandem Asymmetric Hydrogenation
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A novel full atom-economic process for the transformation of alkynes into chiral alcohols by TfOH-catalyzed hydration coupled with Ru-catalyzed tandem asymmetric hydrogenation in TFE under simple conditions has been developed. A range of chiral alcohols was obtained with broad functional group tolerance, good yields, and excellent stereoselectivities.
- Liu, Sensheng,Liu, Huan,Zhou, Haifeng,Liu, Qixing,Lv, Jinliang
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p. 1110 - 1113
(2018/02/23)
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- Molecular Defined Molybdenum-Pincer Complexes and Their Application in Catalytic Hydrogenations
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A family of low-valent molybdenum complexes, supported by the pincer ligand (iPr2PCH2CH2)2NH, was prepared and characterized. After activation by NaBHEt3 coordination compounds 2 and 3-Cl were found to be suitable catalysts for the hydrogenation of ketones and olefins.
- Leischner, Thomas,Spannenberg, Anke,Junge, Kathrin,Beller, Matthias
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supporting information
p. 4402 - 4408
(2019/01/03)
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- Chemoselective transfer hydrogenation of nitroarenes, ketones and aldehydes using acylthiourea based Ru(II)(p-cymene) complexes as precatalysts
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A new series of Ru(II)(η6-p-cymene) complexes (1–5) was synthesized from pyridine based acylthiourea ligands (L1-L5) and [Ru(η6-p-cymene)Cl2]2. All the ligands and complexes were well characterized by UV-Visible, FT-IR, mass and 1H & 13C NMR spectroscopic techniques. The molecular structures of the ligands (L1, L2, L4 and L5) and complex 1 were confirmed using single crystal X-ray diffraction study. The Ru(II)(η6-p-cymene) complexes (1–5) were proved to be efficient precatalysts for the transfer hydrogenation of carbonyl compounds and nitroarenes in the presence of 2-propanol as a hydrogen donor and KOH as a base. The catalytic transfer hydrogenation reactions were chemoselective towards the nitro group in presence of carbonyl group, which is a rare scenario in homogeneous catalysis. The catalyst was compatible with broad range of substrates which include furfural, quinone and many heterocycles. The catalytic reactions exhibited very high conversions (upto 100%) and excellent yields (upto 99%). Turn Over Number (TON) was found upto 990.
- Sathishkumar, Pushpanathan N.,Raveendran, Neethi,Bhuvanesh, Nattamai S.P.,Karvembu, Ramasamy
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- Aluminum Monohydride Catalyzed Selective Hydroboration of Carbonyl Compounds
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The well-defined aluminum monohydride compound [{(2,4,6-Me3-C6H2)NC(Me)}2(Me)(H)]AlH·(NMe2Et) (1) catalyzes hydroboration of a wide range of aldehydes and ketones under mild reaction conditions. Moreover, compound 1 displayed chemoselective hydroboration of aldehydes over ketones at rt.
- Jakhar, Vineet Kumar,Barman, Milan Kr.,Nembenna, Sharanappa
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supporting information
p. 4710 - 4713
(2016/09/28)
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- Stable and Inert Cobalt Catalysts for Highly Selective and Practical Hydrogenation of C≡N and C=O Bonds
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Novel heterogeneous cobalt-based catalysts have been prepared by pyrolysis of cobalt complexes with nitrogen ligands on different inorganic supports. The activity and selectivity of the resulting materials in the hydrogenation of nitriles and carbonyl compounds is strongly influenced by the modification of the support and the nitrogen-containing ligand. The optimal catalyst system ([Co(OAc)2/Phenα-Al2O3]-800 = Cat. E) allows for efficient reduction of both aromatic and aliphatic nitriles including industrially relevant dinitriles to primary amines under mild conditions. The generality and practicability of this system is further demonstrated in the hydrogenation of diverse aliphatic, aromatic, and heterocyclic ketones as well as aldehydes, which are readily reduced to the corresponding alcohols.
- Chen, Feng,Topf, Christoph,Radnik, J?rg,Kreyenschulte, Carsten,Lund, Henrik,Schneider, Matthias,Surkus, Annette-Enrica,He, Lin,Junge, Kathrin,Beller, Matthias
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supporting information
p. 8781 - 8788
(2016/08/02)
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- New Type of 2,6-Bis(imidazo[1,2-a]pyridin-2-yl)pyridine-Based Ruthenium Complexes: Active Catalysts for Transfer Hydrogenation of Ketones
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Neutral and cationic ruthenium(II) complexes bearing a symmetrical 2,6-bis(imidazo[1,2-a]pyridin-2-yl)pyridine were synthesized and structurally characterized by NMR analysis and X-ray crystallographic determinations. These complexes have exhibited good catalytic activity in the transfer hydrogenation of ketones. In refluxing isopropyl alcohol, the conversion of the substrates reached up to 99%, and a TOF value of 356400 h-1 with 0.1 mol % catalyst was achieved. (Figure Presented).
- Li, Ke,Niu, Jun-Long,Yang, Ming-Ze,Li, Zhen,Wu, Li-Yuan,Hao, Xin-Qi,Song, Mao-Ping
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p. 1170 - 1176
(2015/04/27)
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- Mechanistic basis for the enantioselectivity of the anaerobic hydroxylation of alkylaromatic compounds by ethylbenzene dehydrogenase
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The enantioselectivity of reactions catalyzed by ethylbenzene dehydrogenase, a molybdenum enzyme that catalyzes the oxygen-independent hydroxylation of many alkylaromatic and alkylheterocyclic compounds to secondary alcohols, was studied by chiral chromatography and theoretical modeling. Chromatographic analyses of 22 substrates revealed that this enzyme exhibits remarkably high reaction enantioselectivity toward (S)-secondary alcohols (18 substrates converted with > 99% ee). Theoretical QM:MM modeling was used to elucidate the structure of the catalytically active form of the enzyme and to study the reaction mechanism and factors determining its high degree of enantioselectivity. This analysis showed that the enzyme imposes strong stereoselectivity on the reaction by discriminating the hydrogen atom abstracted from the substrate. Activation of the pro(S) hydrogen atom was calculated to be 500 times faster than of the pro(R) hydrogen atom. The actual hydroxylation step (i.e., hydroxyl group rebound reaction to a carbocation intermediate) does not appear to be enantioselective enough to explain the experimental data (the calculated rate ratios were in the range of only 2-50 for pro(S): pro(R)-oriented OH rebound).
- Szaleniec, Maciej,Dudzik, Agnieszka,Kozik, Bart?omiej,Borowski, Tomasz,Heider, Johann,Witko, Ma?gorzata
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- TRANSITION METAL CATALYSTS FOR HYDROGENATION AND HYDROSILYLATION
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Phosphoranimide-metal catalysts and their role in hydrogenation and hydrosilylation are disclosed. The catalysts comprise first row transition metals such as nickel, cobalt or iron. The catalysts have a metal to anionic phosphoranimide ratio of 1:1. This disclosure presents a process for catalytic hydrogenation and hydrosilylation of a range of unsaturated organic compounds under lower temperature and pressure conditions than conditions associated with industrial hydrogenation and hydrosilylation.
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Paragraph 0138
(2014/07/08)
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- Two-component supramolecular helical architectures: Creation of tunable dissymmetric cavities for the inclusion and chiral recognition of the third components
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The inclusion and chiral recognition of racemic arylalkanols by supramolecular helical architectures consisting of enantiopure primary amines and achiral carboxylic acids were thoroughly studied. Among the architectures examined, a supramolecular helical architecture composed of the salt of enantiopure erythro-2-amino-1.2-diphenylethanol (1b) and benzoic acid (2a) was found to include a wide variety of racemic arylalkanols with recognition of their chirality. The helical architecture gave a dissymmetric 1D groove in the salt crystal, and the arylalkanols were enantioselectively included in the groove. The size and shape of the groove were tunable by proper selection of the achiral carboxylic acid component. The origin of the chiral recognition with the combination 1b/2a is discussed on the basis of X-ray crystallographic analyses.
- Kodama, Koichi,Kobayashi, Yuka,Saigo, Kazuhiko
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p. 2144 - 2152
(2008/02/04)
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- Benzylic oxidation of aromatics with cerium(IV) triflate; Synthetic scope and mechanistic insight
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The synthetic utility of cerium(IV) triflate Ce(OTf)4 as a reagent for benzylic oxidation has been tested for a variety of aromatic compounds. Insight is provided into various factors that govern these oxidations and their progress. It has been shown that the mode of preparation of Ce(OTf)4 and the % H2O present in the sample have a marked influence on oxidation ability. A variety of mono- and dialkylbenzenes, haloalkylbenzenes, bicyclic and tricyclic ring systems, and alkoxybenzenes have been surveyed. The method offers an easy to perform one-pot reaction for the room temperature synthesis of aromatic ketones and aldehydes from aromatics and has the potential to find wider application.
- Laali, Kenneth K.,Herbert, Mark,Cushnyr, Brad,Bhatt, Anand,Terrano, David
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p. 578 - 583
(2007/10/03)
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- New water-soluble diamine complexes as catalysts for the hydrogenation of ketones under hydrogen pressure
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New water-soluble rhodium and iridium complexes of 2,2'-bipyridines, functionalized with PO3Na2 groups, show very good catalytic activities in the reduction of various substituted acetophenones under hydrogen pressure in basic aqueous media. No significant loss of catalyst activity is observed after one use.
- Penicaud, Virginie,Maillet, Celine,Janvier, Pascal,Pipelier, Muriel,Bujoli, Bruno
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p. 1745 - 1748
(2007/10/03)
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- Reduction of Alkyl Alkyl, Aryl Alkyl and Cyclic Ketones by Catalytic Hydrogen Transfer over Magnesium Oxide
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The reduction of a series of alkyl alkyl, aryl alkyl and cyclic ketones by catalytic hydrogen transfer (CTR) from isopropyl alcohol over magnesium oxide has been investigated.CTR over MgO was found to be an effective and selective route to the corresponding methanols.At temperatures above 523 K parasubstituted phenylmethanols underwent consecutive dehydration leading to the formation of the corresponding styrene derivative with satisfying yields.These processes were studied in a flow system working continuously.A long-time stability of the catalyst activity has been demonstrated.
- Kijenski, Jacek,Glinski, Marek,Czarnecki, Jacek
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p. 1695 - 1698
(2007/10/02)
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