- Tandem imine formationviaauto-hydrogen transfer from alcohols to nitro compounds catalyzed by a nanomagnetically recyclable copper catalyst under solvent-free conditions
-
A direct imination reaction was developed by tandem reaction of alcohols and nitro compounds in the presence of Cu-isatin Schiff base-γ-Fe2O3as a nanomagnetically recyclable catalyst under solvent-free conditions. By this method, various imines were prepared in good to high yields from one-pot reaction of various alcohols (primary aromatic and aliphatic) and nitro compounds (aromatic and aliphatic)viaan auto-hydrogen transfer reaction. Use of an inexpensive and easily reusable catalyst, without requiring any additives or excess amounts of benzyl alcohol as the reaction solvent are the other advantages of this method. This catalytic system has the merits of cost effectiveness, environmental benignity, excellent recyclability and good reproducibility.
- Derakhshan, Seyed Ruhollah,Hosseini Moghadam, Hadis,Sansano, José Miguel,Sobhani, Sara
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p. 19121 - 19127
(2021/06/03)
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- Metal- and oxidant-free electrochemically promoted oxidative coupling of amines
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The selective oxidation of amines into imines is a priority research topic in organic synthesis and has attracted much attention over the past few decades. However, the oxidation of amines generally suffers from the drawback of transition-metal, even noble-metal catalysts. Thus, the strategy of metal- and oxidant-free selective synthesis of imines is highly desirable yet largely unmet. This paper unravels a metal-free and external oxidant-free electrochemical strategy for the oxidative coupling methodology of amines. This general transformation is compatible with various functional amines and led to functionalized imines in moderate to satisfactory yields.
- Chen, Hengyu,Hu, Xiude,Huang, Xianqiang,Li, Jiashuai,Li, Zhen,Liu, Gang,Liu, Sen,Shen, Guodong,Yang, Bingchuan,Zhang, Yalin
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p. 118 - 122
(2022/01/19)
-
- Discovery of tert-amine-based RORγt agonists
-
The nuclear receptor retinoic acid receptor-related orphan receptor gamma-t (RORγt) is a transcription factor regulating Th17 cell differentiation and proliferation from naive CD4+ T cells. Since Th17 cells have demonstrated the antitumor efficacy by eliciting remarkable activation of CD8+ T cells, RORγt agonists could be applied as potential small molecule therapeutics for cancer immunotherapy. Based on the previously reported RORγt agonist 1 and its resolved co-crystal structure, a series of new tertiary amines were designed, synthesized and biologically evaluated, yielding optimal moieties with improved chemical properties and biological responses. The combination of these optimal moieties resulted in identification of novel RORγt agonists such as 8b with further elevated RORγt agonism responses at a target-based level as well as in cell-based assays, which provided some structural knowledge for further optimization of RORγt agonists as small molecule therapeutics for cancer immunotherapy.
- Qiu, Ruomeng,Yu, Mingcheng,Gong, Juwen,Tian, Jinlong,Huang, Yafei,Wang, Yonghui,Xie, Qiong
-
-
- Efficient Co-Catalyzed Double Hydroboration of Nitriles: Application to One-Pot Conversion of Nitriles to Aldimines
-
The commercially available and bench-stable Co(acac)2/dpephos system is employed as a precatalyst for selective and efficient room temperature hydroboration of organic nitriles with HBPin to produce a series of N,N-diborylamines [RN(BPin)2], which react in situ with aldehydes to give aldimines. Formation of aldimines from N,N-diborylamines does not require a dehydrating agent, is applicable to a wide range of N,N-diborylamine and aldehyde substrates and is highly chemoselective, being unaffected by various common functional groups, such as alkenes, alkynes, secondary amines, ketones, esters, amides, carboxylic acids, pyridines, nitriles, and nitro compounds. The overall transformation represents a synthetically valuable approach to aldimines from nitriles and can be performed in a sequential one-pot manner, tolerating ester, lactone, carboxamide and unactivated alkene functionalities.
- Gudun, Kristina A.,Slamova, Ainur,Hayrapetyan, Davit,Khalimon, Andrey Y.
-
supporting information
p. 4963 - 4968
(2020/04/17)
-
- Tunable Synthesis of α-Amino Boronic Esters from Available Aldehydes and Amines through Sequential One-Pot Dehydration and Copper-Catalyzed Borylacylation
-
Copper-catalyzed multicomponent borylacylation of imines with acid chlorides and bis(pinacolato)diboron was developed for the preparation of synthetically useful and pharmacologically relevant α-amino boronic acid derivatives. Starting from a range of acid chlorides and imines with aryl, heteroaryl, and alkyl substituents, most of these ligand-free reactions proceeded smoothly at room temperature in moderate to good yields. Furthermore, a facile and convenient one-pot, multistep access to the direct synthesis of α-amino boronic acid derivatives from available aldehydes and amines was also developed.
- Xia, Qi,Chang, Hua-Rong,Li, Juan,Wang, Jia-Yi,Peng, Yan-Qing,Song, Gong-Hua
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p. 2716 - 2724
(2020/01/31)
-
- Selective Synthesis of Secondary and Tertiary Amines by Reductive N-Alkylation of Nitriles and N-Alkylation of Amines and Ammonium Formate Catalyzed by Ruthenium Complex
-
A new ruthenium catalytic system for the syntheses of secondary and tertiary amines via reductive N-alkylation of nitriles and N-alkylation of primary amines is proposed. Isomeric complexes 8 catalyze transfer hydrogenation and N-alkylation of nitriles in ethanol to give secondary amines. Unsymmetrical secondary amines can be produced by N-alkylation of primary amines with alcohols via the borrowing hydrogen methodology. Aliphatic amines were obtained with excellent yields, while only moderate conversions were observed for anilines. Based on kinetic and mechanistic studies, it is suggested that the rate determining step is the hydrogenation of intermediate imine to amine. Finally, ammonium formate was applied as the amination reagent for alcohols in the presence of ruthenium catalyst 8. Secondary amines were obtained from primary alcohols within 24 hours at 100 °C, and tertiary amines can be produced after prolonged heating. Secondary alcohols can only be converted to secondary amines with moderate yield. Based on mechanistic studies, the process is suggested to proceed through an ammonium alkoxy carbonate intermediate, where carbonate acts as an efficient leaving group.
- Alshakova, Iryna D.,Nikonov, Georgii I.
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p. 5370 - 5378
(2019/06/14)
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- The preparation and photocatalytic activity of Ag-Pd/g-C3N4 for the coupling reaction between benzyl alcohol and aniline
-
In this study, the carrier g-C3N4 was prepared by melamine, and the Ag-Pd/g-C3N4 catalyst was synthesized by the NaBH4 reduction method. Different characterization techniques, including SEM, TEM, XRD, UV–vis DRS, XPS, photoluminescence spectra (PL) and BET, were employed to investigate the morphology and optical properties of the as-prepared samples. The Ag-Pd/g-C3N4 catalyst was used for the synthesis of imine from a benzyl alcohol and aniline. The results show that when the total loading of Ag and Pd is 2 wt%, and the mass ratio of Ag and Pd is 1:1, the activity of the catalyst is the highest (The highest conversion of aniline is 86.7% and the product selectivity is >99%.). The reaction is optimized by changing the type of solvent, the type and amount of base, the type of catalyst, and the amount of reactants. The optimal reaction conditions are 6 ml of n-hexane, 1.4 mmol of Cs2CO3, 50 mg of the Ag-Pd/g-C3N4 (2 wt%, 1:1), and 2:1 mol ratio of benzyl alcohol and aniline. Under optimal reaction conditions, alcohol derivatives and amine derivatives were investigated to determine the suitable range of the catalyst for alcohols and amines. Then, the effects of different light intensities and wavelengths on the reaction were explored. Additionally, the catalyst's recycling ability was tested, and it was found to be relatively stable. The effect of reactive groups on the mechanism shows that the reaction is mainly achieved by the synergy between h+, e? and ·O2?.
- Ma, Jingjing,Yu, Xiujuan,Liu, Xiaoling,Li, Haiying,Hao,Li, Jingyi
-
-
- A visible-light-responsive metal-organic framework for highly efficient and selective photocatalytic oxidation of amines and reduction of nitroaromatics
-
Photocatalysis is a green synthetic method for organics transformation. We present here the synthesis of a novel visible-light-responsive metal-organic framework and its photocatalytic application. The prepared MOF is highly efficient for the self-coupling of primary amines and oxidative dehydrogenation of secondary amines to selectively produce imines assisted by the green and economic oxidant of molecular oxygen. Studies reveal that both energy transfer and electron transfer from the photoexcited MOF to molecular oxygen are important for amine oxidation, where the highly reactive species of superoxide radicals and singlet oxygen together account for the high catalytic performance. The photogenerated electrons of the MOF have also been utilized for the reduction of aromatic nitroarenes. Results show that they are highly selective for the reduction of nitroarenes to produce anilines in the presence of hydrazine hydrate. The work demonstrates the enormous potential of photoactive MOFs for converting organic substrates into valuable chemicals.
- Chen, Peiqi,Guo, Zhifen,Liu, Xin,Lv, Hui,Che, Yan,Bai, Rong,Chi, Yanhong,Xing, Hongzhu
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p. 27074 - 27080
(2019/12/11)
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- Synthesis and evaluation of Zn(II) dithiocarbamate complexes as potential antibacterial, antibiofilm, and antitumor agents
-
Four complexes having the formula [Zn(L)2] [L1 = (C18H20NS2 –), N-(4-isopropyl-benzyl)-(benzyl)-dithiocarbamate], [L2 = (C10H12NS2 –), N-(benzyl)-(ethyl)-dithiocarbamate], [L3 = (C19H22ONS2 –), N-(4-isopropyl-benzyl)-(4-methoxy-benzyl)-dithiocarbamate], and [L4 = (C16H16NS2 –), N-(benzyl)-(4-methyl-benzyl)-dithiocarbamate] have been contemplated, synthesized, and characterized by elemental analysis and IR, 1H, 13C NMR and UV–visible absorption spectra. All Zn(II) complexes have similar geometry and coordination number. Complex A2 (with ligand L2) crystallizes in triclinic system with space group P-1 having distorted square pyramidal geometry which was stabilized by weak C–H···π and C–H···S intramolecular interactions. The antibacterial, antibiofilm, and antitumor activities of the complexes have been screened and A2 and A3 showed their prominence. Interestingly, both A2 and A3 showed more killing potential against multi-drug resistant gram-positive isolates with MIC indices of 16 μg mL?1 and 16 μg mL?1, respectively, against both MRSA and MSSA, while the antitumor agent A3 showed its prominence with GI50 and LC50 41.15 and 133.73 μg mL?1, respectively.
- Maurya, Vinay Kumar,Singh, Ashish Kumar,Singh, Ravi Pratap,Yadav, Shivangi,Kumar, Krishna,Prakash, Pradyot,Prasad, Lal Bahadur
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p. 3338 - 3358
(2019/11/26)
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- Method for synthesizing imine by catalytic oxidation of asymmetric secondary amine in presence of visible light
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The invention belongs to the technical field of chemical engineering and pharmaceutical industry, and particularly relates to a method for synthesizing imine by catalytic oxidation of asymmetric secondary amine in the presence of visible light. With aza-metalloporphyrin containing sulfur as a visible light catalyst, 1,8-diazabicycloundecene-7-alkene as an auxiliary agent, and oxygen as an oxidant,asymmetric secondary amine is subjected to catalytic oxidation under irradiation of visible light of lambda being larger than or equal to 420nm, so as to obtain the oxidation product imine. A new andefficient imine production way is provided.
- -
-
Paragraph 0025-0026; 0060-0064
(2018/11/22)
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- A telescopic one-pot synthesis of β-lactam rings using amines as a convenient source of imines
-
A facile synthetic approach to substituted β-lactams was designed, using secondary benzylic amines and acid chlorides as starting materials. The reactions proceeded smoothly and all the products were obtained in good yields.
- Rajam?ki, Suvi H. M.,De Luca, Lidia,Capitta, Francesca,Porcheddu, Andrea
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p. 38553 - 38557
(2016/06/01)
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- 1-Cyanoformamidines. Formation during the RuO4-mediated oxidation of secondary amines
-
When performed in the presence of cyanide and at pH smaller than 5, the RuO4-mediated oxidation of secondary amines Bn-NH-R (1a-b; R=Me, Et) gave mainly 1-cyanoformamidines Bn-NR-C(=NH)-CN (2a-b) and their hydrolysis products Bn-NR-COCN (3a-b), Bn-NR-CN (4a-b), Bn-NR-CONH2 (5a-b). Carboxamides 5a-b can result also directly from 1a-b. (Chemical Equation Presented).
- Florea, Cristina,Stavarache, Cristina,Petride, Horia
-
p. 319 - 325
(2016/10/11)
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- RuO4-mediated oxidation of secondary amines. Part 1. Are hydroxylamines the main intermediates?
-
The RuO4-catalyzed oxidation of secondary amines Bn-NH-CH2R (1a and b; R=H, Me) gave mainly amides, but minute amounts of nitrones PhCH=N(O)-CH2R (9a and b) and traces of Bn-N(OH)-CH2R (R=H, 4a) were also detect
- Florea, Cristina A.,Petride, Horia
-
p. 475 - 486
(2016/07/20)
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- Lamellar Ni/Al-SBA-15 fibers: Preparation, characterization, and applications as highly efficient catalysts for amine and imine syntheses
-
A novel Ni/Al-SBA-15 fiber catalyst with a lamellar structure was prepared by the urea precipitation method and successfully utilized in the environmental-friendly reduction of nitro functionality. The applications of the catalyst in highly efficient one-pot amine and imine syntheses were developed; the physicochemical properties of the samples were evaluated with ICP-OES, N2 adsorption, XRD, HRTEM, and EDX. This new catalyst highlights potent catalytic activities and a simple recycling process as an important environmentally-friendly feature.
- Ren, Ren,Ma, Jiantai
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p. 74802 - 74810
(2015/09/21)
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- Aerobic oxidative N-dealkylation of secondary amines in aqueous solution catalyzed by rhodium porphyrins
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N-dealkylation demonstrates an important biochemical oxidation reaction by cytochrome P450 and other monooxygenases. In this article, catalytic oxidative N-dealkylation of secondary amines was achieved using rhodium(III) tetra (p-sulfonato-phenyl) porphyrin ((TSPP)RhIII) in aqueous solution with oxygen as the sole oxidant. Addition of benzaldehyde to trap primary amine product inhibited catalyst deactivation and dramatically increased reaction turnover numbers (TONs). Substrate scope examination suggested the reaction was performed with a preference for bulkier secondary amines. Kinetic study exhibited first-order kinetics with regard of (TSPP)RhIII catalyst. Results from the Hammett study gave a σ value of -1.38, suggesting formation of an iminium ion intermediate in the rate determining step.
- Yun, Lin,Zhen, Ling,Wang, Zikuan,Fu, Xuefeng
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p. 937 - 943
(2015/05/27)
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- Aerobic oxidative N-dealkylation of secondary amines in aqueous solution catalyzed by rhodium porphyrins
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N-dealkylation demonstrates an important biochemical oxidation reaction by cytochrome P450 and other monooxygenases. In this article, catalytic oxidative N-dealkylation of secondary amines was achieved using rhodium(III) tetra (p-sulfonato-phenyl) porphyrin ((TSPP)RhIII) in aqueous solution with oxygen as the sole oxidant. Addition of benzaldehyde to trap primary amine product inhibited catalyst deactivation and dramatically increased reaction turnover numbers (TONs). Substrate scope examination suggested the reaction was performed with a preference for bulkier secondary amines. Kinetic study exhibited first-order kinetics with regard of (TSPP)RhIII catalyst. Results from the Hammett study gave a ρ value of -1.38, suggesting formation of an iminium ion intermediate in the rate determining step.
- Yun, Lin,Zhen, Ling,Wang, Zikuan,Fu, Xuefeng
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p. 937 - 943
(2015/06/16)
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- Highly efficient aerobic oxidation of various amines using Pd3Pb intermetallic compounds as catalysts
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Intermetallic Pd3Pb supported on Al2O3 can act as a highly efficient heterogeneous catalyst for the oxidation of various amines including primary, secondary, aromatic, aliphatic, and cyclic amines. The Royal Society of Chemistry 2014.
- Furukawa, Shinya,Suga, Akifusa,Komatsu, Takayuki
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p. 3277 - 3280
(2014/03/21)
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- Direct synthesis of amides from amines using mesoporous Mn-SBA-12 and Mn-SBA-16 catalysts
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Manganese incorporated SBA-12 and SBA-16 catalyze the tandem reaction of aliphatic primary amine, aerial oxygen and ammonia solution at moderate conditions producing amide in yields as high as 50 mol%. The Mn-SBA-12 and Mn-SBA-16 catalysts with Si/Mn outp
- Kumar, Anuj,Nepak, Devadutta,Srinivas, Darbha
-
-
- Aromatic aldehyde-catalyzed gas-phase decarboxylation of amino acid anion via imine intermediate: An experimental and theoretical study
-
It is generally appreciated that carbonyl compound can promote the decarboxylation of the amino acid. In this paper, we have performed the experimental and theoretical investigation into the gas-phase decarboxylation of the amino acid anion catalyzed by the aromatic aldehyde via the imine intermediate on the basis of the tandem mass spectrometry (MS/MS) technique and density functional theory (DFT) calculation. The results show that the aromatic aldehyde can achieve a remarkable catalytic effect. Moreover, the catalytic mechanism varies according to the type of amino acid: (i) The decarboxylation of α-amino acid anion is determined by the direct dissociation of the C-C bond adjacent to the carboxylate, for the resulting carbanion can be well stabilized by the conjugation between α-carbon, C=N bond and benzene ring. (ii) The decarboxylation of non-α-amino acid anion proceeds via a SN2-like transition state, in which the dissociation of the C-C bond adjacent to the carboxylate and attacking of the resulting carbanion to the C=N bond or benzene ring take place at the same time. Specifically, for β-alanine, the resulting carbanion preferentially attacks the benzene ring leading to the benzene anion, because attacking the C=N bond in the decarboxylation can produce the unstable three or four-membered ring anion. For the other non-α-amino acid anion, the C=N bond preferentially participates in the decarboxylation, which leads to the pediocratic nitrogen anion.
- Xiang, Zhang
-
p. 149 - 156
(2013/10/22)
-
- 2-ARYL IMIDAZO[1,2-A]PYRIDINE-3-ACETAMIDE DERIVATIVES, PREPARATION METHODS AND USE THEREOF
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Disclosed are 2-arylimidazo[1,2-a]pyridine-3-acetamide derivatives represented by formula I, their tautomer, racemate or optical isomer, their pharmaceutically acceptable salt, or their solvates, wherein R1, R2, R3 and R4 are defined as in the specification. Preparation methods of said compounds and use of said compounds in treating and/or preventing central nervous system disease associated with TSPO functional disorder
- -
-
Paragraph 0060
(2013/05/09)
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- Nitrous oxide as a primary product in base-mediated β-elimination reactions of diazeniumdiolated benzylamine derivatives
-
We report an unexpected β-elimination pathway by which diazeniumdiolated benzylamines of structure Bn-N(R)-N(O)N-OR′ undergo base-mediated fragmentation to generate N2O as the only gaseous product. The reaction is especially rapid for R = 2-hydroxyethyl, in which the hydroxyl group anchimerically assists benzylic proton removal with concomitant expulsion of PhCHNR and R′OH.
- Biswas, Debanjan,Cao, Zhao,Keefer, Larry K.,Saavedra, Joseph E.
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supporting information; experimental part
p. 5931 - 5933
(2012/08/14)
-
- Nucleophilic and acid catalyst behavior of a protic ionic liquid in a molecular reaction media. Part 1
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This work presents a new approach using ionic liquids, namely ethylammonium nitrate. The aim was to analyze how the addition of small amounts of a protic ionic liquid to a pure molecular solvent, modifies the microscopic characteristics of a reaction medium. In order to achieve this, a kinetic study of nucleophilic aromatic substitution reactions between 1-fluoro-2, 4-dinitrobenzene and 1-butylamine or piperidine was developed in this type of binary mixtures. We have detected nucleophiles competition originated by the presence of the ionic solvent at very low concentrations, observing the ethylamine derivative as the main substitution product. Moreover, in the light of previous results we have confirmed that the protic ionic liquid can act as both Broensted acid and/or nucleophile. In this connection, we have selected the nucleophilic addition of amines to carbonyl compounds as reaction model. The protic ionic liquid in the presence of aromatic aldehydes substituted by electron-donating groups makes possible the formation of the corresponding imines with good yields. The results demonstrated that the influence of the protic ionic liquid is very important in the course of both reaction systems. Copyright
- Adam, Claudia G.,Fortunato, Graciela G.,Mancini, Pedro M.
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scheme or table
p. 460 - 465
(2010/04/30)
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- Synthesis of 2-alkyl-1-aryl-1,2-dihydrochromeno[2,3-c]pyrrole-3,9-dione derivatives
-
A preparative procedure for the synthesis of 2-alkyl-1-aryl-1,2- dihydrochromeno[2,3-c]pyrrole-3,9-diones from methyl 4-(o-hydroxyphenyl)-2,4- dioxobutanoate, aromatic aldehyde, and aliphatic amine is described.
- Vydzhak,Panchishin, S. Ya.
-
experimental part
p. 2391 - 2397
(2009/05/30)
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- Cobalt-catalyzed carbonylation of N-alkylbenzaldimines to 'N-alkylphthalimidines' (=2,3-dihydro-1H-isoindol-1-ones) via tandem C-H activation and cyclocarbonylation
-
The reaction of N-alkylbenzaldimines with carbon monoxide (CO) in the presence of cobalt (Co) catalysts resulted in the formation of N-alkylphthalimidines (Table 1). Their formation is proposed to occur by C-H activation of the aryl ring, migratory insertion of the hydride species into the benzaldimine functionality, CO coordination, and insertion into the Co-C bond, followed by reductive elimination of the N-alkylphthalimidine and regeneration of the starting Co species (Scheme 4). Deuterium (2H)-labeling NMR studies are consistent with this mechanism (Scheme 5).
- Funk, Jeffrey K.,Yennawar, Hemant,Sen, Ayusman
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p. 1687 - 1695
(2007/10/03)
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- Reductive amination of aldehydes and ketones with sodium borohydride supported onto HZSM-5 zeolite under microwave irradiation in a solvent free system
-
Sodium borohydride supported onto a HZSM-5 zeolite is presented as a general reducing agent for the reductive amination of aldehydes and ketones under microwave irradiation in solventless system. Copyright Taylor & Francis Inc.
- Oskooie, Hossein A.,Amiri, Somaih Solemani,Heravi, Majid M.,Ghassemzadeh, Mitra
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p. 2047 - 2050
(2007/10/03)
-
- Spin trapping chemistry of iminyl free radicals
-
The iminyl radicals formed from hydrogen atom abstraction between tert-butoxyl radicals and benzylidene-N-alkyl-or N-arylamines were trapped by 2-methyl-2-nitrosopropane and investigated by EPR spectroscopy. The compounds investigated were benzylidene N-methyl, ethyl, 1-propyl, 1-butyl, 2-methylpropyl, 1-methylethyl, 1-methylpropyl, 1-ethylpropyl, 1-methylbutyl and cyclohexyl derivative and also benzylidene N-phenyl, 4-tolyl, 4-fluorophenyl, 4-methoxyphenyl, 4-chlorophenyl, 4-nitrophenyl and 4-trifluoromethylphenyl derivatives. In every case the iminyl nitroxide (aminoxyl) was produced in benzene at room temperature. The nitrogen hyperfine splitting constants were in the ranges 3.39-3.56 and 9.68-9.77 G for the iminyl and nitroxyl nitrogens, respectively, for the benzylidene-N-alkylamines and 3.60-3.77 and 8.45-9.15 G for the iminyl and nitroxyl nitrogens, respectively, for the benzylidene-N-arylamines. Very little evidence was found for hydrogen atom abstraction from the alkyl groups attached to the imine function. The absolute rate constant for hydrogen atom abstraction of the iminyl hydrogen was estimated to be 1.2 × 104 M-1 s-1 based on competitive experiments with addition of tert-butoxyl radicals to 2-methyl-2-nitrosopropane (1.5 × 106 M-1 s-1). This value is considerably slower than that for benzaldehyde (2.4 × 107 M-1 s-1).
- Janzen, Edward G.,Nutter, Dale E.
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p. 131 - 140
(2007/10/03)
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- Reaction of 2-Azaallyl Anions with Hydrazonyl Chlorides
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2-Azaallyl anions, obtained from N-benzylidenebenzylamine and potassium carbonate in the presence of tetrabuylammonium bromide as phase-transfer catalyst, regioselectively react with N-phenylhydrazonyl chlorides, yielding only cyclic products, Δ2-1,2,4-triazolines. 2-Azaallyl anions give the same products with nitrilimines generated from hydrazonyl chlorides.
- Abramov, M. A.,Petrov, M. L.
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p. 264 - 266
(2007/10/03)
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- Three-Component Cyclocondensations. Two Methods for the Efficient Preparation of 5-Aminothiazolium Salts via the Reaction of Isocyanides Either with Dimethylthioformamide and Imino Chloro Sulfides or Benyaldimines and Aryl Chlorothioformates
-
Treatment of imino chloro sulfides with dimethylthioformamide and isocyanides at room temperature provides selectively the 5-amino-4-(dimethylamino)-2-(methylthio) (or phenylthio)thiazolium salts.Similarly, the reactions of p-tolyl chlorothionoformate and phenyl chlorodithioformate with a mixture of benzaldimine and isocyanide afford rapidly the 5-amino-4-phenylthiazolium salts.We suggest that these reactions involve the N-(thiocarbonyl)formamidinium and benzylideniminium chlorides as transient intermediates, which are trapped by isocyanides according to a cycloaddition process.The structure of the thiazolium salts and some of their reactivities are discussed.
- Berree, Fabienne,Malvaut, Yvelise,Marchand, Evelyne,Morel, Georges
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p. 6022 - 6029
(2007/10/02)
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- A Facile Oxidation of Secondary Amines to Imines by Iodosobenzene or by a Terminal Oxidant and Manganese or Iron Porphyrins and Manganese Salen as the Catalysts
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The oxidation of secondary amines to imines by iodosobenzene or catalysed by either manganese(III) or iron(III) porphyrins, or by a manganese(III) salen complex with iodosobenzene as the oxygen donor has been investigated.Both aromatic and aliphatic amines can be oxidized smoothly to the corresponding imines with iodosobenzene as the oxidant and the elimination of hydrogen takes place towards the least substituted carbon.Manganese(III) and iron(III) porphyrins and manganese(III) salen are found to catalyse the oxidation of secondary amines to imines with iodosobenzene as the terminal oxidant.Those amines that are less reactive when iodosobenzene is the oxidant, can be converted to the imines in higher yields if a catalyst is added, compared with the uncatalysed reaction.By-products such as carbonyls and nitrones are found in some of these reactions.The manganese(III) salen complex is found to be the best catalyst, followed by manganese(III) porphyrin and iron(III) porphyrin.On the basis of Hammett plots, isotopic labelling studies and other experimental investigations the mechanisms for the uncatalysed and catalysed amine-to-imine oxidations are discussed.
- Larsen, Jan,Joergensen, Karl Anker
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p. 1213 - 1217
(2007/10/02)
-
- Reactions of N-(arylsulfonoxy)-N-alkylbenzylamines with MeONa-MeOH. Steric effect on the structure of the imine-forming transition state
-
Elimination reactions of N-(arylsulfonoxy)-N-alkylbenzylamines 1-5 with MeONa-MeOH have been studied kinetically. The elimination reactions are regiospecific, producing only corresponding benzylidenalkylamines. The rate equation for the reactions is kobs = k0 + k2[MeONa], indicating that the reactions proceed by competing solvolytic- and base-promoted pathways. The relative rates of elimination for the k2 and k0 pathways are 1, 0.67, 0.53, 0.35, and 0.27 for R = Me, Et, i-Pr, s-Bu, and t-Bu and 1, 4.1, 5.1, and 8.7 for R = Et, i-Pr, s-Bu, and t-Bu, respectively. For MeONa-promoted elimination from 1-5, Hammett ρ and kH/kD decrease but ρ1g and |β1g| increase with a bulkier alkyl substituent. However, the values for the solvolytic eliminations are nearly the same for all substrates and are similar to those for the base-promoted pathway, except for the ρ values, which have opposite signs. From these results, the changes in transition-state structure wrought by variation of N-alkyl substituents are assessed.
- Cho, Bong Rae,Pyun, Sang Yong
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p. 3920 - 3924
(2007/10/02)
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- 1-(Triphenylphosphorylideneaminomethyl)benzotriazole (BETMIP) a Novel +CH2N= Synthetic Equivalent: Its Application to the Synthesis of Carbodiimides, Imines, Isothiocyanates, Aziridines, and Secondary Amines
-
One-carbon homologation has been achieved in novel syntheses of the title compounds by one-pot reaction of 1-(triphenylphosphorylideneaminomethyl)benzotriazole (1) with Grignard reagents followed by in situ transformations of the phosphorazene functionality with isocyanates, aldehydes, carbon disulfide, ethylene oxide, and alkyl halides, respectively.
- Katritzky, Alan R.,Jiang, Jinglong,Urogdi, Laszlo
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p. 565 - 567
(2007/10/02)
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- Reactions of N-Chloro-N-alkylbenzylamines with Amines in Acetonitrile. Origin of Steric Effect in Imine-Forming Elimination
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Reaction of N-chloro-N-alkylbenzylamines in which the alkyl group is Me, Et, i-Pr, sec-Bu, and t-Bu with MeNH2 and Et2NH in MeCN have been studied kinetically.The eliminations are quantitative and regiospecific, producing only N-benzylidenealkylamines.The relative rates of elimination for Me/Et/i-Pr/sec-Bu/t-Bu alkyl substituents are 1/0.6/0.4/0.3/0.1 with MeNH2 and 1/0.5/0.3/0.2/0.03 with Et2NH, respectively.Comparison with published data reveals that Charton's value for the imine-forming elimination decreases with the variation of the base-solvent from MeONa-MeOH to MeNH2-MeCN but increases when the base is changed from MeNH2 to Et2NH.For a given base, Hammett ρ and kH/kD values decrease and the ΔH(excit.) and ΔS(excit.) values increase with bulkier alkyl substituents.From these results, the origin of the steric effect in imine-forming elimination is attributed to the repulsive interaction between the alkyl group and the base in the transition state.
- Cho, Bong Rae,Suh, Young Wook
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p. 2855 - 2858
(2007/10/02)
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- Reactions of N-Chlorobenzylalkylamines with Sodium Methoxide in Methanol. Steric Effects in Elimination Reactions
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Reactions of N-chlorobenzylalkylamines in which the alkyl group is Me, Et, i-Pr, t-Bu, and sec-Bu with MeONa-MeOH have been investigated kinetically.The eliminations are quantitative and regiospecific, producing only benzylidenealkylamines.The reactions are first order in base and first order in substrate, and an E2 mechanism is evident.The relative rates of elimination at 25 deg C are 1/0.5/0.3/0.2/0.01 for Me/Et/i-Pr/sec-Bu/t-Bu alkyl substituents, respectively.The results are attributed to repulsive interaction between the alkyl group and the base in the transition state.Hammett ρ and kH/kD values decreased, but the ΔH(excit.) and ΔS(excit.) values increased with bulkier alkyl substituents.Changes in the transition-state parameters with the substrate steric effect are interpreted with variation in structure of the imine-forming transition states.
- Cho, Bong Rae,Maeng, Jun Ho,Yoon, Jong Chan,Kim, Tae Rin
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p. 4752 - 4756
(2007/10/02)
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- Benzylamines: Synthesis and evaluation of antimycobacterial properties
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The synthesis of benzylamines with various N-alkyl chains and substituents in the aromatic system as well as their evaluation on Mycobacterium tuberculosis H 37 Ra are described. The most active compounds in this test, N-methyl-3-chlorobenzylamine (MIC 10.2 μg/mL), N-methyl-3,5-dichlorobenzylamine (93, MIC 10.2 μg/mL), and N-butyl-3,5-difluorobenzylamine (MIC 6.4 μg/mL), also exhibited a marked inhibitory effect on Mycobacterium marinum and Mycobacterium lufu used for the determination of antileprotic properties. The combination of 93 with aminosalicylic acid, streptomycin, or dapsone exert marked supra-additive effects on M. tuberculosis H 37 Ra.
- Meindl,Von Angerer,Schonenberger,Ruckdeschel
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p. 1111 - 1118
(2007/10/02)
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- Is Oxygen Abstraction by Nucleophilic Reagents a Characteristic Reaction of Oxaziridines ?
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The reaction of oxaziridines with nucleophilic reagents was studied.The summarized results are as follows. (1) The nucleophilic reactions occur preferentially on the nitrogen atom and the oxaziridine decomposes into a carbonyl compound and an ylide. (2) The reaction site shifts from nitrogen toward oxygen as the bulk of the ring substituents increases. (3) Cis isomers show faster reaction than trans isomers. (4) The carbon atom of the oxaziridine ring is completely inert to nucleophilic reagents.
- Hata, Yoshiteru,Watanabe, Masamichi
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p. 610 - 614
(2007/10/02)
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