- Implication of a Silyl Cobalt Dihydride Complex as a Useful Catalyst for the Hydrosilylation of Imines
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Here, we describe the formation and use of silyl cobalt (III) dihydride complexes as powerful catalysts for the hydrosilylation of a variety of imines starting from a low-valent well-defined cobalt (I) complex. The reaction is efficient at low catalyst loadings with a diverse range of imines bearing various protecting groups, as well as aliphatic ketimines and quinoline. Kinetics, DFT calculations, NMR spectroscopic studies, deuteration experiments, and X-ray diffraction analyses allowed us to propose a catalytic cycle based on silyl dihydrocobalt (III) complexes performing a hydrocobaltation.
- Barbazanges, Marion,Bories, Cassandre C.,Derat, Etienne,Petit, Marc
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p. 14262 - 14273
(2021/11/27)
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- Iron-catalysed 1,2-aryl migration of tertiary azides
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1,2-Aryl migration of α,α-diaryl tertiary azides was achieved by using the catalytic system of FeCl2/N-heterocyclic carbene (NHC) SIPr·HCl. The reaction generated aniline products in good yields after one-pot reduction of the migration-resultant imines.
- Wei, Kaijie,Yang, Tonghao,Chen, Qing,Liang, Siyu,Yu, Wei
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p. 11685 - 11688
(2020/10/19)
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- Borane-Catalyzed Chemoselectivity-Controllable N-Alkylation and ortho C-Alkylation of Unprotected Arylamines Using Benzylic Alcohols
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An unprecedented protocol for the efficient and highly chemoselective alkylation of unprotected arylamines using alcohols catalyzed by B(C6F5)3 has been developed. The reaction gives N-alkylated products and ortho C-alkylated products in different solvents in good chemoselectivities and yields. Control experiments and DFT calculations indicated that the borane underwent alcohol/arylamine exchange to ensure catalytic activity, and a possible mechanism involving a carbocation is proposed.
- Meng, Shan-Shui,Tang, Xiaowen,Luo, Xiang,Wu, Ruibo,Zhao, Jun-Ling,Chan, Albert S. C.
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p. 8397 - 8403
(2019/09/03)
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- Improving C=N bond reductions with (Cyclopentadienone)iron complexes: Scope and limitations
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Herein, we broaden the application scope of (cyclo-pentadienone)iron complexes 1 in C=N bond reduction. The catalytic scope of pre-catalyst 1b, which is more active than the “Kn?lker complex” (1a) and other members of its family, has been expanded to the catalytic transfer hydrogenation (CTH) of a wider range of aldimines and ketimines, either pre-isolated or generated in situ. The kinetics of 1b-promoted CTH of ketimine S1 were assessed, showing a pseudo-first order profile, with TOF = 6.07 h–1 at 50 % conversion. Moreover, the chiral complex 1c and its analog 1d were employed in the enantioselective reduction of ketimines and reductive amination of ketones, giving fair to good yields and moderate enantioselectivity.
- Cettolin, Mattia,Bai, Xishan,Lübken, Dennis,Gatti, Marco,Facchini, Sofia Vailati,Piarulli, Umberto,Pignataro, Luca,Gennari, Cesare
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p. 647 - 654
(2018/10/24)
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- Efficient Synthesis of Amines by Iron-Catalyzed C=N Transfer Hydrogenation and C=O Reductive Amination
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Here we report the catalytic transfer hydrogenation (CTH) of non-activated imines promoted by a Fe-catalyst in the absence of Lewis acid co-catalysts. Use of the (cyclopentadienone)iron complex 1, which is much more active than the classical ‘Kn?lker complex’ 2, allowed to reduce a number of N-aryl and N-alkyl imines in very good yields using iPrOH as hydrogen source. The reaction proceeds with relatively low catalyst loading (0.5–2 mol%) and, remarkably, its scope includes also ketimines, whose reduction with a Fe-complex as the only catalyst has little precedents. Based on this methodology, we developed a one-pot CTH protocol for the reductive amination of aldehydes/ketones, which provides access to secondary amines in high yield without the need to isolate imine intermediates. (Figure presented.).
- Facchini, Sofia Vailati,Cettolin, Mattia,Bai, Xishan,Casamassima, Giuseppe,Pignataro, Luca,Gennari, Cesare,Piarulli, Umberto
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supporting information
p. 1054 - 1059
(2018/01/27)
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- Enhanced Catalytic Activity of Oxygen-Tethered IrIII NHC Complexes in Aqueous Transfer Hydrogenative Reductive Amination Reactions: Experimental Kinetic and Mechanistic Study
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The synthesis and characterization of seven new IrIII complexes containing o-phenoxide or o-naphthoxide chelated N-heterocyclic carbene ligands is reported herein. The crystal structures of six of the complexes have been determined. These complexes efficiently catalyze the transfer hydrogenative reductive amination (RA) of carbonyls and amines in water. Amongst the complexes tested, the introduction of o-naphthoxide on a nitrogen atom of imidazole based NHC ligand greatly increased the catalytic activity. The catalytic system has a broad substrate scope, which allows the synthesis of a variety of amines in excellent yields and with high turnover numbers up to 490 (for ketones) and 14800 (for aldehydes). The mechanism of aqueous RA reaction with an o-aryloxide chelated NHC-IrIII catalyst has been investigated by NMR spectroscopy and kinetic measurements. These studies suggest that the transfer hydrogenation (TH) is turnover-limited by the hydride formation step. As a result of the 1H NMR studies, the higher catalytic activity of o-naphthoxide chelated catalyst (3 g) over o-phenoxide chelated one (3 b) can be attributed partly due to the faster formation of an iridium hydride, the key intermediate in the RA reactions.
- ?zbozkurt, ?brahim Kayahan,Gülcemal, Derya,Günnaz, Salih,G?k?e, Ayta? Gürhan,?etinkaya, Bekir,Gülcemal, Süleyman
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p. 3593 - 3604
(2018/08/03)
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- Cyclometalated palladium pre-catalyst for N-alkylation of amines using alcohols and regioselective alkylation of sulfanilamide using aryl alcohols
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Simple pyrazole based palladacycle-phosphine with a high turnover has been developed and applied for the N-alkylation of amines and sulfanilamide using alcohols as substrates by hydrogen borrowing strategy. N-alkylation of primary and secondary amines resulted in high isolated yields at 100–130 °C, under solvent free conditions. More challenging secondary aliphatic as well as aromatic alcohols were also successfully utilized as alkylating agents under similar reaction conditions. The turn over number reached up to 43000 for N-benzylation of aniline using benzyl alcohol. Notably, regioselective N-alkylation of 2-aminobenzothiazole and 4-aminobenzenesulfonamide to the corresponding 2-N-(alkylamino)azoles and 4-amino-(N-alkyl)benzenesulfonamides using alcohols as alkylating agents have been achieved using our new pre-catalyst-phosphine system.
- Mamidala, Ramesh,Mukundam, Vanga,Dhanunjayarao, Kunchala,Venkatasubbaiah, Krishnan
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supporting information
p. 2225 - 2233
(2017/03/24)
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- Solvent- and catalyst-free direct reductive amination of aldehydes and ketones with Hantzsch ester: Synthesis of secondary and tertiary amines
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A facile and rapid method for the parallel synthesis of a series of secondary and tertiary amines by the direct reductive amination of aldehydes and ketones with Hantzsch ester under solvent- and catalyst-free has been developed. The scope and limitation of this method are described.
- Nguyen, Quynh Pham Bao,Kim, Taek Hyeon
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p. 4938 - 4943
(2013/07/25)
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- S-benzyl isothiouronium chloride as a recoverable organocatalyst for the direct reductive amination of ketones with Hantzsch ester
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The direct reductive amination of ketones using the Hantzsch ester in the presence of S-benzyl isothiouronium chloride as a recoverable organocatalyst is reported. A wide range of ketones as well as amines were found to give the expected products in moder
- Nguyen, Quynh Pham Bao,Kim, Taek Hyeon
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experimental part
p. 1977 - 1982
(2012/08/07)
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- Trifluoromethanesulfonic acid as an efficient catalyst in the reduction of ketimines
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Trifluoromethanesulfonic acid was found to be highly efficient catalyst in the reduction of ketimines with Hantzsh esters as the hydrogen source. The catalyst loading could be decreased to 1 mol %. Moderate to excellent isolated yields (up to 99 %) were obtained under mild conditions.
- Li, Jianhui,Wang, Zhouyu,Jiang, Zhenju,Jiang, Shengqian
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experimental part
p. 3101 - 3103
(2012/01/06)
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- Palladium-catalyzed asymmetric hydrogenation of simple ketimines using a Bronsted acid as activator
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Using a catalytic amount of a Bronsted acid as activator of simple imines, the highly enantioselective homogeneous palladium-catalyzed asymmetric hydrogenation of simple ketimines was successfully developed with up to 95% ee.
- Zhou, Xiao-Yu,Bao, Ming,Zhou, Yong-Gui
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supporting information; experimental part
p. 84 - 88
(2011/03/23)
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- An easy and general iron-catalyzed reductive amination of aldehydes and ketones with anilines
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A will of iron: An iron-catalyzed reductive amination of aldehydes and ketones with anilines using molecular hydrogen is presented. Under mild conditions, high yields for a broad range of aryl, alkyl, and heterocyclic ketones as well as aldehydes are achieved. Copyright
- Fleischer, Steffen,Zhou, Shaolin,Junge, Kathrin,Beller, Matthias
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experimental part
p. 2240 - 2245
(2012/06/18)
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- Multicomponent C-alkylation reactions of aromatic aldimines with trialkylboranes reagents
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The one-pot three-component reaction of an aryl aldehyde, an arylamine, and a trialkylborane in the presence of hydrogen peroxide afforded the alkylated arylamines 1 in good yields via oxidized imine-borane complexes. In addition, the versatility of our procedure has been confirmed by the use of enolizable aldehydes, alkylic amines, and cyclic imines.
- Valpuesta, Maria,Munoz, Carmen,Diaz, Amelia,Torres, Gregorio,Suau, Rafael
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experimental part
p. 1934 - 1942
(2010/06/13)
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- Zinc(II)-catalyzed addition of grignard reagents to ketones
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(Figure presented) The addition of organometallic reagents to carbonyl compounds has become a versatile method for synthesizing tertiary and secondary alcohols via carbon-carbon bond formation. However, due to the lack of good nucleophilicity or the presence of strong basicity of organometallic reagents, the efficient synthesis of tertiary alcohols from ketones has been particularly difficult and, thus, limited. We recently developed highly efficient catalytic alkylation and arylation reactions to ketones with Grignard reagents (RMgX: R = alkyl, aryl; X = Cl, Br, I) using ZnCl2, Me3SiCH 2MgCl, and LiCl, which effectively minimize problematic side reactions. In principle, RMgBr and RMgI are less reactive than RMgCl for the addition to carbonyl compounds. Therefore, this novel method with homogeneous catalytic ZnCl2·Me3SiCH2MgCl·LiCl is quite attractive, since RMgBr and RMgI, which are easily prepared and/or commercially available, like RMgCl, can be applied successfully. As well as ketones and aldehydes, aldimines were effectively applied to this catalysis, and the corresponding secondary amines were obtained in high yield. With regard to mechanistic details concerning β-silyl effect and salt effect, in situ-prepared [R(Me3SiCH2)2Zn] -[Li]+[MgX2]m[LiCl]n (X = Cl/Br/I) is speculated to be a key catalytic reagent to promote the reaction effectively. The simplicity of this reliable ZnCl2·Me 3SiCH2MgCl·LiCl system in the addition of Grignard reagents to carbonyl compounds might be attractive for industrial as well as academic applications.
- Hatano, Manabu,Ito, Orie,Suzuki, Shinji,Ishihara, Kazuaki
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supporting information; experimental part
p. 5008 - 5016
(2010/10/04)
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- Enantioselective radical addition reactions to imines using binaphthol-derived chiral N-triflyl phosphoramides
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Binaphthol-derived chiral phosphoric acid catalysts were applied to enantioselective radical addition reactions of imines and provided chiral amines with good enantioselectivities (73-84% ee). Furthermore, the enantioselectivities were not affected by eit
- Lee, Sunggi,Kim, Sunggak
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experimental part
p. 3345 - 3348
(2009/09/05)
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- Triazole-Au(I) complexes: A new class of catalysts with improved thermal stability and reactivity for intermolecular alkyne hydroamination
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(Chemical Equation Presented) A series of 1,2,3-triazole-bound cationic Au(I) catalysts have been synthesized, and their structures have been characterized by X-ray crystallography. Variable-temperature NMR studies revealed dynamic triazole-Au cation coor
- Duan, Haifeng,Sengupta, Sujata,Petersen, Jeffrey L.,Akhmedov, Novruz G.,Shi, Xiaodong
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supporting information; experimental part
p. 12100 - 12102
(2009/12/30)
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- Novel one-pot synthesis of N-alkyl arylamines from oxime ethers using organometallic reagents
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A novel one-pot synthesis of α,α-disubstituted secondary arylamines from oxime ethers has been developed by two separate additions of organometallic reagents. As a related arylamine construction, very efficient synthesis of N-(diallyl)methyl arylamines is
- Mukhopadhyay, Partha P.,Miyata, Okiko,Naito, Takeaki
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p. 1403 - 1406
(2008/02/13)
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- Cerium(IV)-promoted ethylation of Schiff bases by triethylaluminum
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Schiff bases Ar1CH=NAr2 that are refractory towards Et3Al are activated at room temperature by cerium(IV) compounds. The ethylation takes place selectively at the methine moiety of the imine. The process is strongly influe
- Tsvelikhovsky, Dmitry,Schumann, Herbert,Blum, Jochanan
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p. 1819 - 1822
(2007/10/03)
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- Diphenylphosphanylsulfoximines as ligands in iridium-catalyzed asymmetric imine hydrogenations
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(Chemical Equation Presented) Easily accessible phosphine-substituted sulfoximines 2 have been applied in Ir-catalyzed asymmetric hydrogenations of acylic N-arylated imines 1. The amines 3 are formed under mild conditions in high yields with excellent ee
- Moessner, Christian,Bolm, Carsten
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p. 7564 - 7567
(2007/10/03)
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- Br?nsted acid catalysis: Organocatalytic hydrogenation of imines
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A new Br?nsted acid catalysed hydrogenation of imines with Hantzsch dihydropyridine as the hydrogen source has been developed. Diphenyl phosphate (DPP) and various other acids catalyse this first metal-free hydrogen transfer to give various amines under m
- Rueping, Magnus,Azap, Cengiz,Sugiono, Erli,Theissmann, Thomas
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p. 2367 - 2369
(2007/10/03)
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- Addition of trialkylalanes to imines under zirconium catalysis
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Trialkylalanes, which are inert toward imines, undergo addition to them in the presence of a catalytic amount of dichlorodicyclopentadienylzirconium(IV) (Cp2ZrCl2). The reaction tolerates the presence of several functional groups in the starting imine such as halo, amide, nitrile, and hydroxy groups. A possible reaction pathway is proposed involving metallacyclic intermediates. Georg Thieme Verlag Stuttgart.
- Denhez, Clement,Vasse, Jean-Luc,Szymoniak, Jan
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p. 2075 - 2079
(2007/10/03)
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- A selective reductive amination of aldehydes by the use of Hantzsch dihydropyridines as reductant
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Direct reductive amination of an aldehyde was carried out using a Hantzsch dihydropyridine as the reductant in the presence of a catalytic amount of scandium triflate. The reaction was highly selective towards aldehydes over ketones, and other reducible functional groups did not affect the reaction.
- Itoh, Takashi,Nagata, Kazuhiro,Miyazaki, Michiko,Ishikawa, Hiroyuki,Kurihara, Ayako,Ohsawa, Akio
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p. 6649 - 6655
(2007/10/03)
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- Reductive amination of aldehydes and ketones by a Hantzsch dihydropyridine using scandium triflate as a catalyst
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Direct reductive amination of aldehydes and ketones was carried out using a Hantzsch dihydropyridine as a reducing agent in the presence of a catalytic amount of a Lewis acid.
- Itoh, Takashi,Nagata, Kazuhiro,Kurihara, Ayako,Miyazaki, Michiko,Ohsawa, Akio
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p. 3105 - 3108
(2007/10/03)
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- Arylative amination of aldehydes promoted by aqueous titanium trichloride
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Free-radical decomposition of arene-diazonium salts 1, catalyzed by aqueous TiCl3, in the presence of aldehydes 2 and anilines 3 leads to secondary amines 4. A mechanism is proposed, according to which the aryl radical adds to the C-atom of the intermediate protonated imine.
- Clerici,Porta
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p. 2069 - 2072
(2007/10/02)
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