- Inverse Hydroboration of Imines with NHC-Boranes Is Promoted by Diphenyl Disulfide and Visible Light
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We describe a simple and efficient procedure for nucleophilic borylation of imines in the absence of a photoredox catalyst. Visible light irradiation of an acetonitrile solution of an imine, an NHC-borane, and diphenyl disulfide (10 mol %) provides various stable α-amino NHC-boranes in good yields. The reaction proceeds via addition of a nucleophilic boryl radical to an imine, followed by hydrogen abstraction from thiophenol, which is generated from NHC-borane and diphenyl disulfide.
- Kawamoto, Takuji,Morioka, Tsubasa,Noguchi, Kohki,Curran, Dennis P.,Kamimura, Akio
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supporting information
p. 1825 - 1828
(2021/03/08)
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- A novel water-dispersible and magnetically recyclable nickel nanoparticles for the one-pot reduction-Schiff base condensation of nitroarenes in pure water
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In this work, a heterogeneous nanocatalyst called Ni-Fe3O4@Pectin~PPA ~ Piconal was first synthesized, which was investigated as a bifunctional catalyst containing nickel functional groups. On the other hand, this Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst in aqueous solvents shows a very effective performance at ambient temperature for the nitroarene reduction reaction with sodium borohydride, for which NaBH4 is considered as a reducing agent. This is a novelty magnetic catalyst that was approved by various methods, including Fourier-transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), Dynamic light scattering (DLS), Transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), Inductively coupled plasma (ICP), Energy-dispersive X-ray spectroscopy (EDX), and Field emission scanning electron microscopy (FESEM) analyses. From the satisfactory results obtained from the reduction of nitrogen, this catalytic system is used for a one-pot protocol containing a reduction-Schiff base concentration of diverse nitroarenes. It was corroborated with the heterogeneous catalytic experiments on the one-pot tandem synthesis of imines from nitroarenes and aldehydes. Finally, the novel Ni-Fe3O4@Pectin~PPA ~ Piconal catalyst could function as a more economically desirable and environmentally amicable in the catalysis field. The favorable products are acquired in good to high performance in the attendance of Ni-Fe3O4@Pectin~PPA ~ Piconal as a bifunctional catalyst. This catalyst can be recycled up to six steps without losing a sharp drop.
- Ghamari Kargar, Pouya,Ravanjamjah, Asiye,Bagherzade, Ghodsieh
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p. 1916 - 1933
(2021/07/10)
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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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- Mechanochemical Transformation of CF3 Group: Synthesis of Amides and Schiff Bases
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We communicate two mild, solvent-free mechanochemical coupling transformations of CF3 group with nitro compounds into amides or Schiff bases employing Ytterbia as a catalyst. This process proceeds via C?F bond activation, accompanied with utilisation of Si-based reductants/oxygen scavengers – reductants of the nitro group. The scope and limitations of the disclosed methodologies are thoroughly studied. To the best of our knowledge, this work is the first example of mechanical energy promoted transformation of the inert CF3 group into other functionalities. (Figure presented.).
- Mkrtchyan, Satenik,Jakubczyk, Micha?,Lanka, Suneel,Yar, Muhammad,Ayub, Khurshid,Shkoor, Mohanad,Pittelkow, Michael,Iaroshenko, Viktor O.
-
supporting information
p. 5448 - 5460
(2021/10/19)
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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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- Application of a catalyst-free Domino Mannich/Friedel-Crafts alkylation reaction for the synthesis of novel tetrahydroquinolines of potential antitumor activity
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A useful and efficient method to construct diversely substituted 1,2,3,4-tetrahydroquinolines in good to excellent yields has been developed through a catalyst-free Domino Mannich and intramolecular Friedel-Crafts alkylation reactions of N-arylamines with
- Castillo, Juan-Carlos,Jiménez, Elizabeth,Portilla, Jaime,Insuasty, Braulio,Quiroga, Jairo,Moreno-Fuquen, Rodolfo,Kennedy, Alan R.,Abonia, Rodrigo
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p. 932 - 947
(2018/02/09)
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- Synergistic Photoredox Catalysis and Organocatalysis for Inverse Hydroboration of Imines
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The first catalytic inverse hydroboration of imines with N-heterocyclic carbene (NHC) boranes has been realized by means of cooperative organocatalysis and photocatalysis. This catalytic combination provides a promising platform for promoting NHC-boryl radical chemistry under sustainable and radical-initiator-free conditions. The highly important functional-group compatibility and possible application in late-stage hydroborations represent an important step forward to an enhanced α-amino organoboron library.
- Zhou, Nengneng,Yuan, Xiang-Ai,Zhao, Yue,Xie, Jin,Zhu, Chengjian
-
supporting information
p. 3990 - 3994
(2018/03/21)
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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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- 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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- 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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- 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
-
supporting information
p. 12274 - 12277
(2016/08/24)
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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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- 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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- 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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- Asymmetric synthesis of indolines through intramolecular shifting of aromatic sulfinyl groups. Role of the π,π-stacking interactions in these unusual SNAr processes
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Cyclization of N-aryl substituted 1-aryl-2[2-p-tolylsulfinyl]phenyl propylamines under LDA, LHMDS, or KHMDS provides a new approach for synthesizing optically pure 2,3-disubstituted indolines. Both the scope and the limitations of this method have been investigated. The π,π-stacking interactions are crucial for these unprecedented intramolecular SNAr processes, in which a sulfinyl group located on a slightly deactivated ring is substituted by amide anions under mild conditions. X-ray and NMR proofs supporting these π,π-stacking interactions are presented.
- Ruano, Jose L. Garcia,Parra, Alejandro,Marcos, Vanesa,Del Pozo, Carlos,Catalan, Silvia,Monteagudo, Silvia,Fustero, Santos,Poveda, Ana
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supporting information; experimental part
p. 9432 - 9441
(2009/12/06)
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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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- 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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- 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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- METHOD OF PRODUCING IMINES
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A method for forming an imine comprises reacting a first reactant comprising a hydroxyl functionality, a carbonyl functionality, or both a hydroxyl functionality and a carbonyl functionality with a second reactant having an amine functionality in the presence of ordered porous manganese-based octahedral molecular sieves and an oxygen containing gas at a temperature and for a time sufficient for the imine to be produced.
- -
-
Page/Page column 3; 7
(2008/06/13)
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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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- Scandium triflate catalyzed cycloaddition of imines with 1,1-cyclopropanediesters: Efficient and diastereoselective synthesis of multisubstituted pyrrolidines
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A tandem ring-opening-cyclization reaction of cyclopropanes with imines in the presence of 5 mol% of scandium triflate was developed for the highly diastereoselective synthesis of multisubstituted pyrrolidines. The Royal Society of Chemistry 2006.
- Kang, Yan-Biao,Tang, Yong,Sun, Xiu-Li
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p. 299 - 301
(2007/10/03)
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- Synthesis of highly substituted unsymmetrical 1,2-diamines, 1,2-diimines, imidazolium salts and imidazolylidenes by aldimine cross-coupling
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α-Aminonitriles derived from aromatic aldehydes and primary amines can be deprotonated quantitatively without the use of protecting groups. The 1,2-addition of the resulting stabilized α-aminocarbanions to imines yields α-aminoimines and the tautomeric enediamines. These unstable compounds can directly be oxidized to 1,2-diimines or reduced to 1,2-diamines in a one-pot reaction. 1,2-Diamines can be obtained in high diastereoselectivity by reduction of the 1,2-diimines. In this case, the relative configuration of the products can be chosen depending on the reduction conditions. Cyclization of the unsymmetrical diimines with halomethyl ethers or esters leads to 1,3,4,5-tetrasubstituted imidazolium salts which can serve as starting materials for the preparation of highly substituted nucleophilic carbenes. Georg Thieme Verlag Stuttgart.
- Kison, Coralie,Opatz, Till
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p. 3727 - 3738
(2008/09/17)
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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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- Thiazolidin-4-one formation. Mechanistic and synthetic aspects of the reaction of imines and mercaptoacetic acid under microwave and conventional heating
-
Microwave irradiation of a mixture of benzylidene-anilines and mercaptoacetic acid in benzene gives 1,3-thiazolidin-4-ones in very high yield (65-90%), whereas the same reaction performed through using the conventional method, at reflux temperature, requires a much longer time and gives a much lower yield (25-69%). This difference seems to be due to some intermediates and by-products formed during the conventional reaction. On the basis of 1H NMR studies, two different mechanisms, acting in benzene and in DMF, respectively, have been hypothesized for the thiazolidin-4-one system formation.
- Bolognese, Adele,Correale, Gaetano,Manfra, Michele,Lavecchia, Antonio,Novellino, Ettore,Barone, Vincenzo
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p. 2809 - 2813
(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)
-
- 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
-
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)
-
- Catalytic, Three-Component Assembly Reaction for the Synthesis of Pyrrolidines
-
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)
-
- Clay/water mixtures - A heterogeneous and ecologically efficient catalyst for the three-component stereoselective synthesis of tetrahydroquinolines
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The three-component synthesis of tetrahydroquinolines 5 from aromatic amines 1, aromatic aldehydes 2 and cyclopentadiene (4) can be efficiently performed in water in the presence of the commercially available bentonite Bieliaca. The overall process involv
- Sartori, Giovanni,Bigi, Franca,Maggi, Raimondo,Mazzacani, Alessandro,Oppici, Giovanni
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p. 2513 - 2518
(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)
-
- Catalytic preparation of aziridines with an iron lewis acid
-
The iron Lewis acid, [(;75-C5H5)Fe(CO)2(THF)]+[BF4]-) was found to be an effective catalyst for the preparation of aziridines. This new method provides a facile, one-step route to predominantly cisaziridines, with yields up to 95%, from compounds with a diazo functionality and a variety of substituted AT-benzylidene imines with N-aryl or AT-alkyl groups. The reaction mechanism is believed to proceed through an electrophilic iminium ion intermediate. To support this idea, the iron Lewis acid-imine complex [(?75-C5H5)Fe(CO)2(PhCH=NPh)]+[BF.j]- was prepared, characterized, and reacted with different diazo compounds to provide the resultant czs-aziridines. Alternatively, it may be possible that the aziridines were derived from an electrophilic carbenoid intermediate, as is often proposed. Thus, the iron carbene [(2-CsIWFeCCOMCHPhOl+LSOaCFg]- was prepared and treated with AT-benzylideneaniline; however, the resultant aziridine was not formed.
- Mayer, Michael F.,Mahmun Hossain
-
p. 6839 - 6844
(2007/10/03)
-
- Copper-Catalyzed Reaction of Terminal Alkynes with Nitrones. Selective Synthesis of 1-Aza-1-buten-3-yne and 2-Azetidinone Derivatives
-
Reaction of arylacetylenes with C,N-diarylnitrones using a catalyst system of CuI-dppe (dppe = 1,2-bis(diphenylphosphino)ethane) in the presence of potassium carbonate in DMF predominantly affords the corresponding 1,2,4-triaryl-1-aza-1-buten-3-ynes in good yields.In contrast, the catalytic reaction using CuI in the presence of an excess amount of pyridine as the ligand gives 1,3,4-triaryl-2-azetidinones as the major products.The reaction with aliphatic terminal alkynes in place of arylacetylenes produces the latter products irrespective of the catalyst system used.Asymmetric induction is also observed in the reaction of phenylacetylene with α,N-diphenylnitrone to give 1,2,4-triphenyl-2-azetidinone in the presence of chiral bisoxazoline-type ligands.
- Miura, Masahiro,Enna, Masahiro,Okuro, Kazumi,Nomura, Masakatsu
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p. 4999 - 5004
(2007/10/03)
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- Benzylideneaniline derivatives
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This invention describes a method of treating inflammation in warm blooded animals by topically administering an effective amount of benzylideneaniline or its derivatives.
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