- Effects of molecular conformation on the spectroscopic properties of 4,4′-disubstituted benzylideneanilines
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The relationship between the molecular conformation and spectroscopic properties of unsymmetrical 4,4′-disubstituted benzylideneanilines, was explored by the combination of experiment and reference data. Crystal structure information and spectroscopic beh
- Fang, Zhengjun,Wu, Feng,Yi, Bing,Cao, Chenzhong,Xie, Xin
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
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Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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- Cooperative catalysis of molybdenum with organocatalysts for distribution of products between amines and imines
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Multi-amino groups and nitrogen donors compound was discovered as an organocatalyst for N-alkylation of alcohols with amines in the presence of Mo(CO)6. The Mo(CO)6/organocatalyst binary system has shown to be a highly active catalyst for the N-alkylation reaction between alcohols and amines with excellent tolerance of variable starting materials bearing different functional groups. Of particular note, this method possessing a superiority selectivity in the synthesis of N-alkylated amines or imines, which can be controlled by the reaction temperature. The cooperative catalysis mechanism in combination of Mo(CO)6 with organocatalyst was elucidated by control experiments.
- Wu, Di,Bu, Qingqing,Guo, Cheng,Dai, Bin,Liu, Ning
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- Insight into the Modes of Activation of Pyridinium and Bipyridinium Salts in Non-Covalent Organocatalysis
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A series of pyridinium and bipyridinium salts were prepared and their catalytic properties were evaluated in the aza-Diels-Alder reaction between imines and Danishefsky diene. Depending on the substituents of the pyridinium/bipyridinium rings and on the nature of the counterion, two mechanisms of activation were demonstrated. In case of non-substituted rings, the substrate is activated through charge transfer involving the aryl ring on the C-side of the imine. When halogen atoms were introduced on the catalysts, the activation mode switched to halogen bond involving the imine nitrogen lone pair. Moreover, alternative activation modes based on hydrogen bonding and radical cation were ruled out. This work allowed us to develop two families of catalysts whose potential was demonstrated in the cycloaddition of various imines with Danishefsky diene. The first family is composed of the simple methyl pyridinium triflate and dioctyl bipyridinium triflate. The former is active only with imines bearing a p-methoxyphenyl group on the C-side and the latter was found to be efficient with imines bearing different substituents on both the N- and C-sides of the imines. The second family is based on halogenated pyridinium salts which proved active with almost all considered imines. (Figure presented.).
- Weiss, Robin,Golisano, Tamara,Pale, Patrick,Mamane, Victor
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supporting information
p. 4779 - 4788
(2021/09/06)
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- A Highly Selective Manganese-Catalyzed Synthesis of Imines under Phosphine-Free Conditions
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An efficient and highly selective phosphine-free NN-manganese(I) complex catalyst system was developed for the acceptorless dehydrogenative coupling of alcohols with amines to form imines. The coupling reactions underwent at 3 mol % catalyst loading, and a large range of alcohols and amines with diverse functional groups was applied, including challenging diol and diamine. The target imine products were obtained in good to excellent yields. The present work provides an alternative method to construct highly active nonprecious metal complex catalysts based on phosphine-free ligands.
- Chai, Huining,Yu, Kun,Liu, Bo,Tan, Weiqiang,Zhang, Guangyao
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p. 217 - 226
(2020/01/31)
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- Synthesis and Reactivity of Fluorinated Triaryl Aluminum Complexes
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The addition of the Grignard 3,4,5-ArFMgBr to aluminum(III) chloride in ether generates the novel triarylalane Al(3,4,5-ArF)3·OEt2. Attempts to synthesize this alane via transmetalation from the parent borane with trimethylaluminum gave a dimeric structure with bridging methyl groups, a product of partial transmetalation. On the other hand, the novel alane Al(2,3,4-ArF)3 was synthesized from the parent borane and trimethylaluminum. Interestingly, the solid-state structure of Al(2,3,4-ArF)3 shows an extended chain structure resulting from neighboring Al···F contacts. Al(3,4,5-ArF)3·OEt2 was then found to be an effective catalyst for the hydroboration of carbonyls, imines, and alkynes with pinacolborane.
- Ould, Darren M. C.,Carden, Jamie L.,Page, Rowan,Melen, Rebecca L.
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supporting information
p. 14891 - 14898
(2020/10/02)
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- Ruthenium N-Heterocyclic Carbene Complexes for Chemoselective Reduction of Imines and Reductive Amination of Aldehydes and Ketones
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Chemoselective reduction of imines to secondary amines is catalyzed efficiently by tethered and untethered, half-sandwich ruthenium N-heterocyclic carbene (NHC) complexes at room temperature. The untethered Ru-NHC complexes are more efficient as catalysts for the reduction of aldimines and ketimines than the tethered complexes. Using the best untethered complex as a catalyst, electronic and steric demands on the reaction was probed using a series of imines. Chemoselectivity of the catalyst towards imine reduction was tested by performing inter and intramolecular competitive reactions in a variety of ways. The catalyst exhibits a very high TON and TOF under anaerobic conditions.
- Kathuria, Lakshay,Samuelson, Ashoka G.
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supporting information
(2020/06/17)
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- Micropores Induced Stereoselective Synthesis of E-imines: Synergistic Effect between Cerium Species and Micropores in CeAlPO-5 Molecular Sieves
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Metal-doped zeolitic microporous materials are often viewed as something extremely negative as catalysis for the reactions involving aromatic molecules because of severe diffusion limitation. For these reasons, many chemists aim to development of the large microporous or hierarchical micro-mesoporous zeolites as supports that allow for the access of the “bulky” reactants. But the “small” micropore with respect to an aromatic molecules-involving reaction is not always a negative point. Here we employed a hierarchical micro-mesoporous CeAlPO-5 molecular sieve (HP-CeAlPO-5) as the catalyst that can catalyze stereoselective synthesis of E-imines through the reaction of alcohols with amines. Control reactions, DFT calculations and GC-MS analyses demonstrated that the feature of the uniform “small” micropore in the HP-CeAlPO-5 catalyst play a key role in the stereoselective synthesis of E-imines. In addition, the reaction tolerates a broad range of alcohols and amines, and can be performed with as little as 0.89 mole percent catalyst in more than 90.6 percent yield and about 99.7 : 0.3 stereoselective ratio. This zeolitic catalyst provides a conceptually new and practical protocol to stereoselective synthesis of E-imine compounds.
- Jin, Yangxin,Cao, Yali,Fang, Guoyong,Ruan, Fei,Ke, Qingping
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p. 3178 - 3181
(2019/07/04)
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- Phosphine-Free Well-Defined Mn(I) Complex-Catalyzed Synthesis of Amine, Imine, and 2,3-Dihydro-1 H-perimidine via Hydrogen Autotransfer or Acceptorless Dehydrogenative Coupling of Amine and Alcohol
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The application of nontoxic, earth-abundant transition metals in place of costly noble metals is a paramount goal in catalysis and is especially interesting if the air- and moisture-stable ligand scaffold is used. Herein, we report the synthesis of amines/imines directly from alcohol and amines via hydrogen autotransfer or acceptorless dehydrogenation catalyzed by well-defined phosphine-free Mn complexes. Both imines and amines can be obtained from the same set of alcohols and amines using the same catalyst, only by tuning the reaction conditions. The amount and nature of the base are found to be a highly important aspect for the observed selectivity. Both the primary and secondary amines have been employed as substrates for the N-alkylation reaction. As a highlight, we showed the chemoselective synthesis of resveratrol derivatives. Furthermore, the Mn-catalyzed dehydrogenative synthesis of structurally important 2,3-dihydro-1H-perimidines has also been demonstrated. Density functional theory calculations were also carried out to model the reaction path and to calculate the reaction profile.
- Das, Kalicharan,Mondal, Avijit,Pal, Debjyoti,Srivastava, Hemant Kumar,Srimani, Dipankar
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supporting information
p. 1815 - 1825
(2019/04/30)
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- Halo-1,2,3-triazolium salts as halogen bond donors for the activation of imines in dihydropyridinone synthesis
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In the past decade halogen bond (XB) catalysis has gained considerable attention. Halo-triazoles are known XB donors, yet few examples detail their use as catalysts. As a continuation of our previous work the catalytic properties of substituted enantiomerically pure halo-triazolium salts were explored in the reaction between an imine and Danishefsky's diene leading to the formation of dihydropyridinone. The catalytic activity of the XB donors was highly dependent on the choice of the halogen atom and on the counterion. Also, it was found that impurities in the diene affected the rate of the reaction.
- Kaasik, Mikk,Metsala, Andrus,Kaabel, Sandra,Kriis, Kadri,J?rving, Ivar,Kanger, Tonis
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p. 4295 - 4303
(2019/03/29)
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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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supporting information
p. 647 - 654
(2018/10/24)
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- Nucleophilic Imines and Electrophilic o-Quinone Methides, a Three-Component Assembly of Assorted 3,4-Dihydro-2 H-1,3-benzoxazines
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A one-pot method for joining three separate components leading to an assortment of N-substituted 3,4-dihydro-2H-1,3-benzoxazines is described. The method involves the addition of a Grignard reagent to an o-OBoc salicylaldehyde in the presence of an imine. With a variety of components, 15 examples are presented, including the diastereoselective incorporation of chiral imines.
- Chen, Peishan Kc,Wong, Yuk Fai,Yang, Derek,Pettus, Thomas R. R.
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supporting information
p. 7746 - 7749
(2019/10/11)
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- Rhodium-catalyzed synthesis of imines and esters from benzyl alcohols and nitroarenes: Change in catalyst reactivity depending on the presence or absence of the phosphine ligand
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The [Rh(COD)Cl]2/xantphos/Cs2CO3 system efficiently catalyzes the reductive N-alkylation of aryl nitro compounds with alcohols by a borrowing-hydrogen strategy to afford the corresponding imine products in good to excellent yields. In the absence of xantphos, the [Rh(COD)Cl]2/Cs2CO3 catalytic system behaves as an effective catalyst for the dehydrogenative coupling of alcohols to esters, with nitrobenzene as a hydrogen acceptor. The reactivity of the rhodium catalytic system can be easily manipulated to selectively afford the imine or ester.
- Song, Taemoon,Park, Ji Eun,Chung, Young Keun
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p. 4197 - 4203
(2018/04/14)
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- Iron-Catalyzed Reductive Ethylation of Imines with Ethanol
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The borrowing hydrogen strategy has been applied to the ethylation of imines with an air-stable iron complex as precatalyst. This approach opens new perspectives in this area as it enables the synthesis of unsymmetric tertiary amines from readily available substrates and ethanol as a C2 building block. A variety of imines bearing electron-rich aryl or alkyl groups at the nitrogen atom could be efficiently reductively alkylated without the need for molecular hydrogen. The mechanism of this reaction, which shows complete selectivity for ethanol over other alcohols, has been studied experimentally and by means of DFT computations.
- Vayer, Marie,Morcillo, Sara P.,Dupont, Jennifer,Gandon, Vincent,Bour, Christophe
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supporting information
p. 3228 - 3232
(2018/03/13)
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- Photo-induced reductive cross-coupling of aldehydes, ketones and imines with electron-deficient arenes to construct aryl substituted alcohols and amines
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Umpolung reactions of C=X bonds (X = O, N) are valuable ways of constructing new C–C bonds, which are sometimes difficult to be constructed using traditional synthetic pathways. Classical polarity inversion of C=X bonds (X = O, N) usually requires air or moisture-sensitive and strong reducing agents, which limit the feasibility of substrate scope. Herein we describe a photo-induced reductive cross-coupling reaction of aldehydes, ketones and imines with electron-deficient arenes (aromatic nitriles) using fac-Ir(ppy)3 as a photocatalyst and diisopropylethylamine (DIPEA) as a terminal reductant under visible light irradiation. Mild conditions and high yields mean that this new polarity inversion strategy can be used with aryl-substituted alcohols and amines. Spectroscopic studies and control experiments have demonstrated the oxidative quenching of Ir(ppy)3* by electron-deficient arenes involved in the key step for the C–C bond formation.
- Liu, Zan,Nan, Xiaolei,Lei, Tao,Zhou, Chao,Wang, Yang,Liu, Wenqiang,Chen, Bin,Tung, Chenho,Wu, Lizhu
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p. 487 - 494
(2018/03/22)
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- Higher Order Constitutional Dynamic Networks: [2×3] and [3×3] Networks Displaying Multiple, Synergistic and Competitive Hierarchical Adaptation
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The present study investigates the constitutional dynamic networks (CDNs) underlying dynamic covalent libraries (DCLs) that extend beyond the [2×2] case toward higher orders, namely [2×3] and [3×3] CDNs involving respectively six and nine constituents generated from the recombination of five and six components linked through reversible chemical reactions. It explores the behavior of such systems under the action of one or two effectors. More specifically and for the sake of proof of principle, it makes use of DCLs involving dynamic organic ligands and analyzes their single and double adaptive response under the action of one and two metal cation effectors. Thus, interconversions within [2×3] DCLs of six constituents (hydrazone, acylhydrazone, and imine ligands) give access to the generation of [2×3] CDNs of 3D trigonal prismatic type consisting of three [2×2] sub-networks and presenting specific responses to the application of Cu+ and Zn2+ metal cation effectors, in particular double agonistic amplification. More complex [3×3] CDNs based on nine ligand constituents of imine, hydrazone, and acylhydrazone types were also designed and subjected to the application of one or two effectors, e.g., Cu+ and Fe2+ metal cations, revealing novel types of adaptive behavior: (i) agonistic amplification between a single constituent and a full [2×2] sub-network, and (ii) agonistic amplification along a single diagonal connecting three constituents. Of special interest is also the dependence of the response of the system to hierarchical sequence of effector application, whereby initial interaction with Cu+ ions results in the destruction of the network, whereas the sequence Fe2+ followed by Cu+ yields a clean three-constituent DCL. Finally and strikingly, the present results also demonstrate that the increase in complexity of the system by introduction of an additional entity leads to a simpler output through dynamic competition between components.
- Men, Guangwen,Lehn, Jean-Marie
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supporting information
p. 2474 - 2483
(2017/02/23)
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- Tris(2,4,6-trifluorophenyl)borane: An Efficient Hydroboration Catalyst
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The metal-free catalyst tris(2,4,6-trifluorophenyl)borane has demonstrated its extensive applications in the 1,2-hydroboration of numerous unsaturated reagents, namely alkynes, aldehydes and imines, consisting of a wide array of electron-withdrawing and donating functionalities. A range of over 50 borylated products are reported, with many reactions proceeding with low catalyst loading under ambient conditions. These pinacol boronate esters, in the case of aldehydes and imines, can be readily hydrolyzed to leave the respective alcohol and amine, whereas alkynyl substrates result in vinyl boranes. This is of great synthetic use to the organic chemist.
- Lawson, James R.,Wilkins, Lewis C.,Melen, Rebecca L.
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supporting information
p. 10997 - 11000
(2017/08/22)
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- β-Selective Reductive Coupling of Alkenylpyridines with Aldehydes and Imines via Synergistic Lewis Acid/Photoredox Catalysis
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Umpolung (polarity reversal) strategies of aldehydes and imines have dramatically expanded the scope of carbonyl and iminyl chemistry by facilitating reactions with non-nucleophilic reagents. Herein, we report the first visible light photoredox-catalyzed β-selective reductive coupling of alkenylpyridines with carbonyl or iminyl derivatives with the aid of a Lewis acid co-catalyst. Our process tolerates complex molecular scaffolds (e.g., sugar, natural product, and peptide derivatives) and is applicable to the preparation of compounds containing a broad range of heterocyclic moieties. Mechanistic investigations indicate that the key step involves single-electron-transfer reduction of aldehydes or imines followed by the addition of resulting ketyl or α-aminoalkyl radicals to Lewis acid-activated alkenylpyridines.
- Lee, Katarzyna N.,Lei, Zhen,Ngai, Ming-Yu
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supporting information
p. 5003 - 5006
(2017/05/04)
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- Combination of Enabling Technologies to Improve and Describe the Stereoselectivity of Wolff-Staudinger Cascade Reaction
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A new, single-mode bench-top resonator was evaluated for the microwave-assisted flow generation of primary ketenes by thermal decomposition of α-diazoketones at high temperature. A number of amides and β-lactams were obtained by ketene generation in situ and reaction with amines and imines, respectively, in good to excellent yields. The preferential formation of trans-configured β-lactams was observed during the [2+2] Staudinger cycloaddition of a range of ketenes with different imines under controlled reaction conditions. Some insights into the mechanism of this reaction at high temperature are reported, and a new web-based molecular viewer, which takes advantage from Augmented Reality (AR) technology, is also described for a faster interpretation of computed data.
- Musio,Mariani,?liwiński,Kabeshov,Odajima,Ley
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supporting information
p. 3515 - 3526
(2016/10/18)
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- Enantioselective and Regiodivergent Functionalization of N-Allylcarbamates by Mechanistically Divergent Multicatalysis
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A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel-catalyzed isomerization of N-allylcarbamates and subsequent phosphoric-acid-catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene-carbamates are mechanistically partitioned to yield opposing functionalized products. Formal α-functionalization to give protected α-arylamines is achieved upon enantioselective Friedel–Crafts reaction with arene nucleophiles, whereas formal β-functionalization is achieved upon reaction with diarylimine electrophiles in an enantioselective Povarov-[4+2] cycloaddition.
- Richmond, Edward,Khan, Ismat Ullah,Moran, Joseph
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supporting information
p. 12274 - 12277
(2016/08/24)
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- O-Naphthoquinone-Catalyzed Aerobic Oxidation of Amines to (Ket)imines: A Modular Catalyst Approach
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A modular aerobic oxidation of amines to imines has been achieved using an ortho-naphthoquinone (o-NQ) catalyst. The cooperative catalyst system of o-NQ and Cu(OAc)2 enabled the formation of homocoupled imines from benzylamines, while the presence of TFA helped the formation of cross-coupled imines in excellent yields. The current mild aerobic oxidation protocol could also be applied to the oxidation of secondary amines to imines or ketimines with the help of cocatalyst, Ag2CO3, with excellent yields.
- Goriya, Yogesh,Kim, Hun Young,Oh, Kyungsoo
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supporting information
p. 5174 - 5177
(2016/10/14)
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- Solvent-free synthesis of azomethines, spectral correlations and antimicrobial activities of some E-benzylidene-4-chlorobenzenamines
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Some azomethines including substituted benzylidene-4-chlorobenzenamines (E-imines) have been synthesized by fly-ash: PTS catalyzed microwave assisted condensation of 4-chloroaniline and substituted benzaldehydes under solvent-free conditions. The yield of the imines has been found to be more than 85%. The purity of all imines has been checked using their physical constants and UV, IR and NMR spectral data. These spectral data have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral data has been studied. The antimicrobial activities of all imines have been studied using standard methods.
- Suresh,Sakthinathan,Kamalakkannan,Ranganathan,Sathiyamoorthi,Mala,Arulkumaran,Vijayakumar,Sundararajan,Vanangamudi,Subramanian,Thirunarayanan,Vanaja,Kanagambal
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p. 275 - 290
(2015/07/27)
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- Stereoselective peterson olefinations from bench-stable reagents and N-phenyl imines
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The synthesis of bench-stable α,α-bis(trimethylsilyl)toluenes and tris(trimethylsilyl)methane is described and their use in stereoselective Peterson olefinations has been achieved with a wide substrate scope. Product stereoselectivity was poor with carbonyl electrophiles (E/Z ~1:1 to 4:1) though this was significantly improved by employing the corresponding substituted N-benzylideneaniline (up to 99:1) as an alternative electrophile. The olefination byproduct was identified as N,N-bis(trimethylsilyl)aniline and could be easily separated from product by aqueous acid extraction. Evidence for an autocatalytic cycle has been obtained.
- Das, Manas,Manvar, Atul,Jacolot, Ma?wenn,Blangetti, Marco,Jones, Roderick C.,O'Shea, Donal F.
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supporting information
p. 8737 - 8740
(2015/06/08)
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- Access to 1,2-dihydroisoquinolines through gold-catalyzed formal [4+2] cycloaddition
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A new synthetic route to the privileged 1,2-dihydroisoquinolines is reported. This method, which relies on a gold-catalyzed formal [4+2] cycloaddition between ynamides and imines, provides a new retrosynthetic disconnection of the 1,2-dihydroisoquinoline core by installing the 1,8a C-C and 2,3 C-N bonds in one step. Both aldimines and ketimines can be used as substrates. In addition, one example of dihydrofuropyridine synthesis is also demonstrated. Heterocycles: A new synthetic route to the privileged 1,2-dihydroisoquinolines is reported. This method, which relies on a gold-catalyzed formal [4+2] cycloaddition between ynamides and imines, provides a new retrosynthetic disconnection of the 1,2-dihydroisoquinoline core by installing the 1,8a C-C and 2,3 C-N bonds in one step. Both aldimines and ketimines can be used as substrates. In addition, one example of dihydrofuropyridine synthesis is also demonstrated (see scheme).
- Xin, Zhuo,Kramer, Soren,Overgaard, Jacob,Skrydstrup, Troels
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supporting information
p. 7926 - 7930
(2014/07/07)
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- Mn-catalyzed three-component reactions of imines/nitriles, grignard reagents, and tetrahydrofuran: An expedient access to 1,5-amino/keto alcohols
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An expedient Mn-catalyzed three-component synthesis of 1,5-amino/keto alcohols from Grignard reagents, imines/nitriles, and tetrahydrofuran (THF) is described, which deviates from the classic Grignard addition to imines/nitriles in THF solvent. THF is split and sewn in an unprecedented manner in the reaction, leading to the formation of two geminal C-C bonds via C-H and C-O cleavage. Mechanistic experiments and DFT calculations reveal radical and organo-Mn intermediates in the catalytic cycle and the α-arylative ring-opening of THF as the key reaction step.
- He, Ruoyu,Jin, Xiqing,Chen, Hui,Huang, Zhi-Tang,Zheng, Qi-Yu,Wang, Congyang
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supporting information
p. 6558 - 6561
(2014/05/20)
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- Stereoselective synthesis of α-alkylidene β-oxo amides by palladium-catalyzed carbonylation
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A direct method to obtain α-alkylidene β-oxo amides by the palladium-catalyzed carbonylation of α-chloro ketones in the presence of aromatic imines has been described. The methodology can be applied to a variety of C-aryl imines bearing N-aryl or N-alkyl substituents. The entire process is highly stereoselective and affords the α-alkylidene β-oxo amides only as (Z) isomers. A mechanistic hypothesis involving an acyl-β-lactam intermediate has also been proposed.
- Perrone, Serena,Salomone, Antonio,Caroli, Antonio,Falcicchio, Aurelia,Citti, Cinzia,Cannazza, Giuseppe,Troisi, Luigino
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p. 5932 - 5938
(2015/03/30)
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- Aerobic oxidative coupling of alcohols and amines over Au-Pd/resin in water: Au/Pd molar ratios switch the reaction pathways to amides or imines
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A facile switch of the reaction pathways of aerobic oxidative coupling of alcohols and amines from amidation to imination was realized for the first time by tuning the Au/Pd ratios in ion-exchange resin supported Au-Pd alloy catalysts (Au-Pd/resin). Amides were obtained with high yields on Au6Pd/resin while imines were obtained over AuPd4/resin. Various alcohols and amines underwent oxidative coupling smoothly in water to afford the desired products with good to excellent yields. Further investigation on the reaction mechanism suggested the synergistic effect between Au and Pd determined the adsorption strength of the aldehyde intermediate, which in turn dictated the reaction pathways. That is, on Au-rich alloys (e.g., Au6Pd) absorbed aldehyde species was formed, followed by further oxidation to yield amides, while on Pd-rich alloys (e.g., AuPd4), free aldehyde was generated, which then underwent condensation with amines to produce imines. The discovery might provide avenues to develop new efficient catalysts for the green synthesis of special chemicals.
- Zhang, Leilei,Wang, Wentao,Wang, Aiqin,Cui, Yitao,Yang, Xiaofeng,Huang, Yanqiang,Liu, Xiaoyan,Liu, Wengang,Son, Jin-Young,Oji, Hiroshi,Zhang, Tao
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p. 2680 - 2684
(2013/10/08)
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- Straightforward synthesis of aromatic imines from alcohols and amines or nitroarenes using an impregnated copper catalyst
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The impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines. This catalyst does not require any type of expensive and difficult to handle organic ligand or typical transition metals, and provides excellent yields achievable under mild reaction conditions. Moreover, the catalyst is very easy to remove from the reaction medium by simply using a magnet. The one-pot process of dehydrogenation of alcohols in the presence of aniline followed by aqueous hydrolysis gave pure alcohols in excellent yields. In addition to amines, nitroarenes could be used as the nitrogen-containing reagent. In the case of primary amines the expected imines were successfully prepared under similar reaction conditions. The impregnated copper on magnetite catalyst is a versatile system for the synthesis of imines starting from alcohols and amines or nitroarenes. A similar synthesis of imines was accomplished using only primary amines. This catalyst avoids the use of expensive organic ligands and other transition metals while enabling excellent yields under mild reaction conditions. Copyright
- Perez, Juana M.,Cano, Rafael,Yus, Miguel,Ramon, Diego J.
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p. 4548 - 4554
(2012/11/07)
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- A new Yb3+-catalyzed pinacol and imine-coupling reaction
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Ytterbium triflate, Yb(OTf)3, catalyzes the intermolecular reductive homocouplings of imines, aldehydes, and ketones at loadings of 5 mol % in the presence of Mg and Me3SiCl to give isolated yields of up to 95%. Diastereoselectivity of up to 4/96 (dl/meso) is achieved for aromatic aldehydes, up to 100% dl for aliphatic aldehydes, and 100% dl for an intramolecular imine coupling.
- Aspinall, Helen C.,Greeves, Nicholas,Hin, Shane Lo Fan
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experimental part
p. 1558 - 1561
(2010/06/13)
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- Heterogeneously catalyzed one-pot synthesis of aldimines from primary alcohols and amines by supported ruthenium hydroxides
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The one-pot synthesis of aldimines from primary alcohols and amines via sequential reactions of alcohol oxidation and dehydrative condensation could efficiently be promoted by supported ruthenium hydroxide catalysts, in particular Ru(OH)x/TiO2. The observed catalysis was truly heterogeneous and the retrieved catalyst could be reused without an appreciable loss of high catalytic performance. Copyright
- Kim, Jung Won,He, Jinling,Yamaguchi, Kazuya,Mizuno, Noritaka
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supporting information
p. 920 - 921,2
(2020/08/31)
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- Tandem catalysis: Direct catalytic synthesis of imines from alcohols using manganese octahedral molecular sieves
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Tandem processes involving catalysts can offer unique and powerful strategies for converting simple starting materials into more complex products in a single reaction vessel. Imines were synthesized directly from alcohols via a tandem catalytic process using manganese octahedral molecular sieves (OMS-2) as catalyst. The synthesis proceeds through two steps: an oxidation of the alcohols to carbonyls followed by the nucleophilic attack by an amine on the carbonyl to form the imine. OMS-2 acts as a bifunctional catalyst and catalyzes two mechanistically distinct processes in a single reaction vessel under the same conditions. Conversions up to 100% were obtained for benzylic alcohols with this efficient, environmentally friendly catalytic reaction. The advantages of this process are that the intermediates need not be isolated and the catalysts can be reused upon simple filtration without loss of activity.
- Sithambaram, Shanthakumar,Kumar, Ranjit,Son, Young-Chan,Suib, Steven L.
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p. 269 - 277
(2008/09/17)
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- Fast and efficient synthesis of pyrano[3,2-c]quinolines catalyzed by niobium(V) chloride
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A highly efficient two-step method for the synthesis of pyranoquinoline derivatives from imino-Diels-Alder reactions between aldimines and 3,4-dihydro-2H-pyran using niobium(V) chloride as catalyst under mild conditions is described. Georg Thieme Verlag Stuttgart.
- Da Silva-Filho, Luiz Carlos,Lacerda Jr., Valdemar,Constantino, Mauricio Gomes,Da Silva, Gil Valdo Jose
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experimental part
p. 2527 - 2536
(2009/04/04)
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- Antifungal and cytotoxic activities of some N-substituted aniline derivatives bearing a hetaryl fragment
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Diverse N-substituted anilines bearing hetaryl fragments were easily prepared from corresponding aldimines derived from commercially available aromatic aldehydes and anilines. 2-Furyl substituted anilines showed very good antifungal activities against dermatophytes, particularly against Trichophyton rubrum (MIC = 3.12-6.25 μg/mL). In addition, all active compounds, 45-47, 73, and 74, were tested for cytotoxic activities against breast (MCF-7), lung (H-460), and central nervous system (SF-268) human cancer cell lines with the NCI-anticancer-drug screen. The activity of amines described in this paper, along with the low toxicity of most of them, shows promise for the future development of non-toxic new antimycotic agents.
- Kouznetsov, Vladímir V.,Vargas Méndez, Leonor Y.,Sortino, Maximiliano,Vásquez, Yelkaira,Gupta, Mahabir P.,Freile, Mónica,Enriz, Ricardo D.,Zacchino, Susana A.
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p. 794 - 809
(2008/09/17)
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- Alkoxy substituted (E,E)-3,6-bis(styryl)pyridazine-a photosensitive mesogen for liquid crystals
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(E,E)-3,6-Bis(styryl)pyridazines (3a-t) bearing 2, 4 or 6 alkoxy chains were prepared by applying the Siegrist reaction of 3,6-dimethylpyridazine (13) and the corresponding azomethines 10a-t. The transversal dipole moment of these calamitic compounds effe
- Lifka, Thorsten,Zerban, Georg,Seus, Peter,Oehlhof, Annette,Meier, Herbert
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p. 6551 - 6560
(2008/09/21)
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- Oxidation of secondary amines catalyzed by dirhodium caprolactamate
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The dirhodium caprolactamate [Rh2(cap)4] catalyzed oxidation of secondary amines to imines by tert-butyl hydroperoxide (TBHP) occurs with high chemo- and regioselectivity. The Royal Society of Chemistry.
- Choi, Hojae,Doyle, Michael P.
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p. 745 - 747
(2007/10/03)
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- π-π Stacking versus steric effects in stereoselectivity control: Highly diastereoselective synthesis of syn-1,2-diarpropylamines
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N-Arylarylideneamines react with sulfinylbenzyl carbanions derived from 2-(p-tolylsulfinyl)toluenes (S)-1 and (S)-2, affording epimeric mixtures at C1 of 1,2-diarylethyl- and 1,2-diarylpropylamine derivatives. The sulfinyl group completely controls the configuration at C2 in the reactions of (S)-2. The configuration at Cl depends on the electron density of the ring adjacent to the iminic carbon atom which is modulated by π-π stacking interactions with the ring joined to the carbanionic centre. The stereoselectivity was controlled by modifying the acceptor character of the arylideneamine ring with appropriate substituents, the formation of the highly selective (R) configuration at C1 being made possible by electron-donating groups. N-(2,4,6-Trimethoxyphenyl) arylideneamines have been shown to be suitable starting materials for the preparation of (R)-1,2-diarylethyl- and (1R,2S)-1,2-diarylpropylamines (syn epimers) in a highly stereoselective manner.
- Garcia Ruano, Jose L.,Aleman, Jose,Alonso, Ines,Parra, Alejandro,Marcos, Vanesa,Aguirre, Jose
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p. 6179 - 6195
(2008/02/13)
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- Preparation of tri- and difluoromethylated amines from aldimines using (trifluoromethyl)trimethylsilane
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Addition of a trifluoromethyl group into aldimines was accomplished using (trifluoromethyl)trimethylsilane with tetraalkylammonium fluorides as initiators, and the resulting adducts were converted to difluoromethylated imines in the presence of excess flu
- Surya Prakash,Mogi, Ryo,Olah, George A.
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p. 3589 - 3592
(2007/10/03)
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- Supramolecular catalysis of Strecker reaction in water under neutral conditions in the presence of β-cyclodextrin
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An environmentally benign and highly efficient procedure for the nucleophilic addition of trimethylsilyl cyanide to imines (Strecker reaction) has been developed under biomimetic conditions in water in the presence of β-cyclodextrin to afford α-aminonitriles in quantitative yields. The use of cyclodextrin precludes the use of either acid or base, and the catalyst can be recycled a number of times without loss in activity.
- Surendra,Srilakshmi Krishnaveni,Mahesh,Rama Rao
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p. 2532 - 2534
(2007/10/03)
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- Isoprene-catalyzed lithiation of imidazole: Synthesis of 2-(hydroxyalkyl)- and 2-(aminoalkyl)imidazoles
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2-Lithioimidazole was prepared by means of a new protocol, which consists of a slight excess of lithium metal in the presence of a substoichiometric amount of isoprene (20 mol%) in THF at room temperature. By reacting this organolithium with carbonyl elec
- Torregrosa, Rosario,Pastor, Isidro M.,Yus, Miguel
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p. 11148 - 11155
(2007/10/03)
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- Highly stereoselective reactions of γ-sulfinyl carbanions with achiral imines
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Lithium 2-p-tolylsulfinylbenzyl carbanions react with different N-substituted imines affording 1,2-diaryl ethyl (and propyl) amines with a high stereoselectivity control at both benzyllic (only dependent of the sulfur configuration) and iminic carbons. The anti:syn ratio, ranging between >96:98, dependent on the electronic density at nitrogen. Copyright Taylor & Francis Inc.
- Ruano, Jose Luis Garcia,Aleman, Jose,Parra, Alejandro
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p. 1209 - 1215
(2007/10/03)
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- Some studies on nucleophilic trifluoromethylation using the shelf-stable trifluoromethylacetophenone-N,N-dimethyltrimethylsilylamine adduct
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The simple thermal addition product of N,N-dimethyltrimethylsilylamine with 2,2,2-trifluoroacetophenone provides a shelf-stable reagent for nucleophilic trifluoromethylation of both the carbonyl and the imine group.
- Motherwell, William B.,Storey, Lynda J.
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p. 491 - 498
(2007/10/03)
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- Torsional vibration and central bond length of N-benzylideneanilines
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The crystal structures of N-benzylideneaniline (1), N-benzylidene-4- carboxyaniline (2), N-(4-methylbenzylidene)-4-nitroaniline (3), N-(4-nitrobenzylidene)-4-methoxyaniline (4), N-(4-nitrobenzylidene)-4- methylaniline (5), W-(4-methoxybenzylidene)aniline (6) and N-(4- methoxybenzylidene)-4-methylaniline (7) were determined by X-ray diffraction analyses at various temperatures. In the crystal structures of all the compounds, an apparent shortening of the central C=N bond was observed at room temperature. As the temperature was lowered, the observed bond lengths increased to approximately 1.28 A at 90 K, irrespective of substituents in the molecules. The shortening and the temperature dependence of the C=N bond length are interpreted in terms of an artifact caused by the torsional vibration of the C - Ph and N - Ph bonds in the crystals. In the crystal structures of (1) and (7), a static disorder around the C=N bond was observed, which is also responsible for the apparent shortening of the C=N bond.
- Harada, Jun,Harakawa, Mayuko,Ogawa, Keiichiro
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p. 578 - 588
(2007/10/03)
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- Synthesis of β-lactams and β-aminoesters via high intensity ultrasound-promoted Reformatsky reactions
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Reformatsky reactions of an imine, an α-bromoester, zinc dust and a catalytic amount of iodine in dioxane under high intensity ultrasound (HIU) irradiation from an ultrasonic probe are explored. A series of 16 aldimines with varying electronic demands is
- Ross, Nathan A.,MacGregor, Robert R.,Bartsch, Richard A.
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p. 2035 - 2041
(2007/10/03)
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- Comparison of the electronic structures of imine and hydrazone side-chain functionalities with the aid of 13C and 15N NMR chemical shifts and PM3 calculations. The influence of C=N-substitution on the sensitivity to aromatic substitution
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Benzaldehyde derivatives possessing a C=N double bond in the side-chain of the aromatic ring exhibit a reverse dependence of the 13C NMR chemical shifts of the C=N carbon on the benzylidenic substituents X. Thus, electron-withdrawing substituents cause shielding (shift is reduced), while electron-donating ones cause deshielding. The origin of this phenomenon, which is in contrast with the idea of the generalized electronic effect, is extensively studied here by comparing the behavior of sets of benzaldehyde derivatives bearing various substitutents Y on the C=N nitrogen (Y-N= CH-C6H4-X). The effects of substituents X on the C=N unit change when Y is varied. Combination of the influences of the substituents X and Y gives a sensitive balance between the different resonance structures of the compounds. Our graphical treatment, where the ρI and ρR values observed for substituent X are plotted against the σp+ value of substituent Y, is a novel use of Hammett-type substituent parameters. The justification of this method and our conclusions could be verified, for instance, by the fair correlation between the ρI or ρR values and the atomic charges of the imine carbon of the unsubstitued phenyl derivatives as well as by the correlations of the relevant bond orders and/or bond lengths both with the substituent parameters and with the atomic charges.
- Neuvonen,Fueloep,Neuvonen,Koch,Kleinpeter,Pihlaja
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p. 2151 - 2160
(2007/10/03)
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- Catalytic, Three-Component Assembly Reaction for the Synthesis of Pyrrolidines
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Equation presented. Copper(I) salts catalyze the three-component assembly reaction between an α-diazo ester, an imine, and various alkenes and alkynes to form substituted pyrrolidines with excellent to good diastereoselectivities in high yields. The transition metal-catalyzed decomposition of the α-diazo compound in the presence of the imine likely generates a transient azomethine ylid that undergoes addition with various dipolarophiles in a highly convergent manner.
- Galliford, Chris V.,Beenen, Melissa A.,Nguyen, Sonbinh T.,Scheidt, Karl A.
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p. 3487 - 3490
(2007/10/03)
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- Oxidative carbon-carbon bond cleavage reaction of 1,2-diamines and 1,2-amino alcohols under an oxygen atmosphere
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Under an atmosphere of oxygen 1,2-diamines underwent clean oxidative cleavage in the presence of BF3·OEt2 to give imines in good to excellent yields. 1,2-Amino alcohols were also cleaved under the same conditions to give imines and a
- Shimizu, Makoto,Makino, Hiroaki
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p. 8865 - 8868
(2007/10/03)
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- Electrochemistry of aminoazines and nitrones: Electrochemical reductions of 2-amino-1,4-pyrazine with nitrones to form amide compounds and electrochemical oxidations of anilines with nitrones to form imine compounds and benzaldehydes
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Electrochemical reductions of 2-amino-1,4-pyrazine in the presence of nitrone derivatives afforded two types of amide compounds, one of which was derived from both the pyrazine and the nitrones and the other from only the nitrones. The analogous reactions
- Saito, Katsuhiro,Kawamura, Ayako,Kanie, Takashi,Ueda, Yosuke,Kondo, Satoru
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p. 1071 - 1080
(2007/10/03)
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- Zr4+-catalyzed efficient synthesis of α-aminophosphonates
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Aldimines undergo nucleophilic addition with diethyl phosphite in the presence of a catalytic amount of zirconium tetrachloride at ambient temperature to afford the corresponding α-aminophosphonates in high yields with high selectivity.
- Yadav,Reddy,Raj,Reddy,Prasad
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p. 2277 - 2280
(2007/10/03)
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- Synthesis and antimicrobial activity of 1,4-diaryl-2-azetidinones
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Cycloaddition of substituted 4,4-benzylidene-anilines to in situ prepared dichloroketenes in the presence of dichloroacetyl chloride and triethylamine affords a variety of 2-azetidinones. All the compounds were characterized by IR and 1H NMR. Their antimicrobial activity, against Gram(+) and Gram(-) bacteria and fungi, was tested. Copyright (C) 2000 Elsevier Science S.A.
- Guener, Vildan,Yildirir, Sueleyman,Oezcelik, Berrin,Abbasoglu, Ufuk
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p. 147 - 150
(2007/10/03)
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