- Synthesis of a novel class of β-lactam derivatives of 1-aminophosphonates by staudinger ketene-imine [2+2]-cycloaddition reaction
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A novel class of β-lactam derivatives of 1-aminophosphonates was synthesized by Staudinger [2+2] cycloaddition reaction of ketenes with imines derived from 1-aminophosphonates. Treatment of aromatic aldehydes with ammonia and diethyl phosphite followed by
- Kaboudin, Babak,Afsharinezhad, Mohammad Bagher
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- Synthesis of a Molybdenum Hydrido(hydrogermylene) Complex and Its Conversion to a Germylyne Complex: Another Route through Dehydrogenation with Nitriles
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A molybdenum germylene complex having Mo-H and Ge-H bonds, Cp*(CO)2(H)Mo=Ge(H){C(SiMe3)3} (1), was synthesized by the reaction of a methyl molybdenum complex with a trihydrogermane and was converted to a germylyne complex, Cp*(CO)2MoGe{C(SiMe3)3} (2), via dehydrogenation with aryl isocyanates under mild heating. A similar conversion from the same germylene complex into the germylyne complex also occurred using nitriles instead of isocyanates, while releasing imines via a Mo-Ge-N three-membered ring complex Cp*(CO)2Mo[κ2(N,Ge)Ge-(N=CHR){C(SiMe3)3}] (4, R = Me and aryl groups) as an intermediate. Formation of imines was confirmed by a trapping experiment with BPh3, which afforded a BPh3-imine adduct. In the case of aryl nitriles, the corresponding three-membered ring intermediates were converted into the germylyne complex efficiently by blue LED light irradiation. TD-DFT calculations on the three-membered-ring intermediate suggest that the role of the LED light is to induce CO ligand dissociation from the intermediate via a metal-to-ligand-charge-transfer (MLCT) transition.
- Dhungana, Tara Prasad,Hashimoto, Hisako,Ray, Mausumi,Tobita, Hiromi
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- Structural characteristics and catalytic performance of nanostructured Mn-doped CeO2 solid solutions towards oxidation of benzylamine by molecular O2
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This work reports a thorough investigation of nanosized Mn-doped ceria (Ce0.7Mn0.3O2-δ, CM) as an efficient catalyst for oxidation of benzylamine under solvent-free conditions. These catalysts were prepared by a coprecipitation method followed by calcination at 773 and 1073?K. Effect of Mn doping was examined by a variety of characterization techniques. XRD results confirmed formation of single-phase Ce-O-Mn solid solution, and TEM studies showed nanosized nature of particles. BET surface area of CeO2 was significantly enhanced after Mn incorporation. Raman, XPS and H2-TPR results revealed that Mn cations in ceria lattice increase concentration of structural oxygen vacancies and reducibility of ceria. Among various catalysts, the CM calcined at 773?K exhibited a high conversion (~71%), product selectivity (~99.8%), and excellent stability. The better performance has been proved to be due to synergetic interaction between Ce and Mn ions thereby enhanced surface area, improved reducibility, and increased surface adsorbed oxygen species.
- Rangaswamy, Agolu,Venkataswamy, Perala,Devaiah, Damma,Ramana, Singuru,Reddy, Benjaram M.
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- Catalytic aerobic photooxidation of primary benzylic amines using hindered acridinium salts
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Hindered acridinium cations, simply prepared by the addition of primary amines to the known methylium tris(2,6-dimethoxyphenyl) cation, catalyze the aerobic photooxidation of primary benzyl amines into benzylimines. A mechanistic rationale for the electron-transfer process is proposed.
- Nicolas, Cyril,Herse, Christelle,Lacour, Jér?me
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- Rapid combinatorial access to macrocyclic ansapeptoids and ansapeptides with natural-product-like core structures
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14-Membered ansa-cyclopeptide alkaloids are among the most abundant natural macrocycles and thus valuable templates for diversity-oriented synthesis with biological relevance. A rapid synthesis of the core structure is conceivable by a combination of an Ugi four-component reaction with bifunctional building blocks to form the dipeptoid part, followed by a suitable macrocyclization reaction. The latter step is crucial, and an uncommon macroetherification gave the best results. The use of ammonium salts allows direct access to peptides instead of peptoids. Depending on the substitution pattern, some cyclopeptoids show planar chirality despite free rotation of the phenylene group. Georg Thieme Verlag Stuttgart.
- De Greef, Michiel,Abeln, Sahan,Belkasmi, Khalid,Doemling, Alexander,Orru, Romano V. A.,Wessjohann, Ludger A.
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- The mechanism of pyrolysis of benzyl azide: Spectroscopic evidence for benzenemethanimine formation
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We study the gas-phase pyrolysis of benzyl azide (BA, C6H5CH2N3) using ultraviolet photoelectron spectroscopy (UVPES) and matrix-isolation infrared (IR) spectroscopy, together with electronic structure calculations and Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. It is found that BA decomposes via N2 elimination at ca. 615 K, primarily yielding benzenemethaninime. Other end products include HCN and C6H6. N-Methyleneaniline is not detected, although its formation at higher temperature is foreseen by RRKM calculations.
- Pinto, Rui M.,Guerra, Mauro,Copeland, Grant,Olariu, Romeo I.,Rodrigues, Paula,Teresa Barros,Lourdes Costa,Dias, António A.
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- Kinetics and mechanism of the oxidation of substituted benzylamines by hexamethylenetetramine-bromine
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The oxidation of substituted benzylamines by hexamethylenetetramine-bromine (HABR) to the corresponding aldimines is first order with respect to each the amine and HABR. It is proposed that HABR itself is the reactive oxidizing species. The oxidation of deuterated benzylamine (PhCD2NH2) indicated a substantial kinetic isotope effect (kH/kD = 5.60 at 293 K). This confirmed the cleavage of an α-C-H bond in the rate-determining step. Correlation analyses of the rates of oxidation of 20 monosubstituted benzylamines were performed with various single-and multi-parametric equations. The rates of the oxidation showed excellent correlations in terms of the Yukawa-Tsuno and Brown equations. The polar reaction constants were negative. The oxidation exhibited extensive cross-conjugation, in the transition state, between the electron-donating substituents and the reaction centre. A mechanism involving a hydride ion transfer from the amine to HABR, in the rate-determining step, is proposed. Copyright
- Dubey, Rashmi,Kothari, Seema,Banerji, Kalyan K.
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- Synergistic Nanostructured MnOx/TiO2 Catalyst for Highly Selective Synthesis of Aromatic Imines
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This work reports the development of a synergistic nanostructured MnOx/TiO2 catalyst, with highly dispersed MnOx nanoparticles (4.5±1 nm) on shape-controlled TiO2 nanotubes (8–11 nm width and 120–280 nm length), for selective synthesis of valuable aromatic imines at industrially important conditions. Pristine TiO2 nanotubes exhibited 97 % imine selectivity at a 38.3 % benzylamine conversion, whereas very low imine selectivity was obtained over commercial TiO2 materials, indicating the catalytic significance of shape-controlled TiO2 nanotubes. The MnOx nanoparticle/TiO2 nanotube (10 wt% Mn) catalyst calcined at 400 °C showed the best activity with 95.6 % benzylamine conversion and 99.9 % imine selectivity. This catalyst exhibited good recyclability for four times and is effective for converting numerous benzylamines into higher yields of imines. The high catalytic performance of MnOx/TiO2 nanotubes was attributed to higher number of redox sites (Mn3+), high dispersion of Mn species, and shape-controlled structure of TiO2, indicating that this catalyst could be a promising candidate for selective oxidation reactions.
- Sudarsanam, Putla,K?ckritz, Angela,Atia, Hanan,Amin, Mohamad Hassan,Brückner, Angelika
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- Visible light-induced N-methyl activation of unsymmetric tertiary amines
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In the presence of methylene group, selective N-methyl activation of tertiary amines has been accomplished with the aid of visible light using organic photocatalyst under air. This protocol explores numerous aliphatic and aromatic substituted tetra-hydroquinoline analogues from various tertiary amines and maleimides. Furthermore, this approach was applied to activate the methyl group of N-methyl carbazole to generate the biologically active molecule.
- Perumal, Gopi,Kandasamy, Mohanraj,Ganesan, Balaji,Govindan, Karthick,Sathya, Harsha,Hung, Min-Yuan,Chandru Senadi, Gopal,Wu, Ya-Ching,Lin, Wei-Yu
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- Platinum Nanoparticles Uniformly Dispersed on Covalent Organic Framework Supports for Selective Synthesis of Secondary Amines
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Covalent organic frameworks (COFs) with pore structures are talented supports for active components. In this report, COF has been rationally fabricated and served as host for growing uniformly dispersed platinum nanoparticles with a narrow size distribution (2 nm). The obtained hybrid Pt/COF exhibits high catalytic activity in the reductive amination of benzaldehyde towards secondary amines with a yield of 96 % and good recyclability. The preferable selectivity towards secondary amines could be attributed to synergistic effects of active platinum nanoparticles and COF, in which metallic Pt nanoparticles were uniformly dispersed with a positively charged surface. This work will open an avenue towards controlling the interaction between active metals and support as well as rational design of catalysts for demanding transformations for fine agrochemicals intermediates.
- Li, Xinjun,Liu, Jianguo,Ma, Longlong,Tang, Long,Wang, Chenguang,Wang, Nan
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- NH4I-mediated sp3 C-H cross-dehydrogenative coupling of benzylamines with 2-methylquinoline for the synthesis of E-2-styrylquinolines
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Without any metal catalyst, a simple and efficient method for the synthesis of E-2-styrylquinolines through sp3 C-H cross-dehydrogenative coupling of benzylamines with 2-methylquinolines mediated by NH4I under air is successfully developed. The oxidative olefination proceeded through deamination and sp3 C–H bond activation. A plausible mechanism is proposed for the construction of E-2-styrylquinolines.
- Huang, Bin,Li, Xue,Liao, WeiBo,Wang, JiangWei,Zhang, YuanYuan
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p. 903 - 910
(2021/07/17)
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- RhNPs supported onN-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity
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Amine and nicotinamide groups grafted on ordered mesoporous silica (OMS) were investigated as stabilizers for RhNPs used as catalysts in the hydrogenation of several substrates, including carbonyl and aryl groups. Supported RhNPs on functionalized OMS were prepared by controlled decomposition of an organometallic precursor of rhodium under dihydrogen pressure. The resulting materials were characterized thoroughly by spectroscopic and physical techniques (FTIR, TGA, BET, SEM, TEM, EDX, XPS) to confirm the formation of spherical rhodium nanoparticles with a narrow size distribution supported on the silica surface. The use of nicotinamide functionalized OMS as a support afforded small RhNPs (2.3 ± 0.3 nm), and their size and shape were maintained after the catalyzed acetophenone hydrogenation. In contrast, amine-functionalized OMS formed RhNP aggregates after the catalytic reaction. The supported RhNPs could selectively reduce alkenyl, carbonyl, aryl and heteroaryl groups and were active in the reductive amination of phenol and morpholine, using a low concentration of the precious metal (0.07-0.18 mol%).
- Pulido-Díaz, Israel T.,Serrano-Maldonado, Alejandro,López-Suárez, Carlos César,Méndez-Ocampo, Pedro A.,Portales-Martínez, Benjamín,Gutiérrez-Alejandre, Aída,Salas-Martin, Karla P.,Guerrero-Ríos, Itzel
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p. 3289 - 3298
(2021/03/16)
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- Kinetic Resolution of α-Silyl-Substituted Allylboronate Esters via Chemo- and Stereoselective Allylboration of Aldehydes
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We describe the kinetic resolution of α-silyl-substituted allylboronate esters via chiral phosphoric acid-catalyzed chemo-, diastereo- and enantioselective allylboration of aldehydes. This process provides two synthetically versatile enantioenriched compo
- Park, Jinyoung,Jung, Yongsuk,Kim, Jeongho,Lee, Eunsung,Lee, Sarah Yunmi,Cho, Seung Hwan
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supporting information
p. 2371 - 2376
(2020/12/01)
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- Enantioselective Allylation of Cyclic and In Situ Formed N-Unsubstituted Imines with Tetraol-Protected Allylboronates
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Tetraol-protected α-chiral allylboronates are utilized in diastereo- and enantioselective transformations of cyclic imines (up to 98 %, d.r. 97 : 3, e.r. 99 : 1). An application to in situ formed N-unsubstituted imines gives in a consecutive one-pot sequence selective access to all four stereoisomers of the homoallylamine within minutes (up to 88 %, d.r. 81 : 19, e.r. 99 : 1). These results underline the usability, tuneability and stability of tetraol-based allylboronates.
- Ullrich, Patrick,Schlamkow, Max A.,Choi, Ching-Yi,Kerkenpa?, Hannah,Hen?en, Birgit,Pietruszka, J?rg
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supporting information
p. 6254 - 6257
(2021/11/03)
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- Copper-Catalyzed Aerobic Oxidation of Amines to Benzothiazoles via Cross Coupling of Amines and Arene Thiolation Sequence
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A one-pot three-component synthesis of benzothiazoles has been developed using the copper-catalyzed aerobic cross coupling of amines followed by arene thiolation using elemental sulfur. The dual roles of elemental sulfur and CuCl(OH)-TMEDA in the aerobic amine oxidation and the aniline thiolation enable the facile access to benzothiazole derivatives from readily available starting materials. The operational simplicity of the current promiscuous catalyst system suggests the high synthetic potential in the preparation of heterocyclic compounds. (Figure presented.).
- Kim, Jihyeon,Oh, Kyungsoo
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p. 3576 - 3582
(2020/08/05)
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- A Journey from Thermally Tunable Synthesis to Spectroscopy of Phenylmethanimine in Gas Phase and Solution
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Phenylmethanimine is an aromatic imine with a twofold relevance in chemistry: organic synthesis and astrochemistry. To tackle both aspects, a multidisciplinary strategy has been exploited and a new, easily accessible synthetic approach to generate stable imine-intermediates in the gas phase and in solution has been introduced. The combination of this formation pathway, based on the thermal decomposition of hydrobenzamide, with a state-of-the-art computational characterization of phenylmethanimine laid the foundation for its first laboratory observation by means of rotational electric resonance spectroscopy. Both E and Z isomers have been accurately characterized, thus providing a reliable basis to guide future astronomical observations. A further characterization has been carried out by nuclear magnetic resonance spectroscopy, showing the feasibility of this synthetic approach in solution. The temperature dependence as well as possible mechanisms of the thermolysis process have been examined.
- Melli, Alessio,Potenti, Simone,Melosso, Mattia,Herbers, Sven,Spada, Lorenzo,Gualandi, Andrea,Lengsfeld, Kevin G.,Dore, Luca,Buschmann, Philipp,Cozzi, Pier Giorgio,Grabow, Jens-Uwe,Barone, Vincenzo,Puzzarini, Cristina
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p. 15016 - 15022
(2020/10/19)
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- Concurrent Formation of N-H Imines and Carbonyl Compounds by Ruthenium-Catalyzed C-C Bond Cleavage of β-Hydroxy Azides
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A commercial cyclopentadienylrutenium dicarbonyl dimer ([CpRu(CO)2]2) efficiently catalyzes the formation of N-H imines and carbonyl compounds simultaneously from β-hydroxy azides via C-C bond cleavage under visible light. Density functional theory calculations for the cleavage reaction support the mechanism involving chelation of alkoxy azide species and liberation of nitrogen as the driving force. The synthetic utility of the reaction was demonstrated by a new amine synthesis promoted by chemoselective allylation of imine and synthesis of isoquinoline.
- Lee, Jeong Min,Bae, Dae Young,Park, Jin Yong,Jo, Hwi Yul,Lee, Eunsung,Rhee, Young Ho,Park, Jaiwook
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p. 4608 - 4613
(2020/06/05)
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- Enantioselective Reductive Coupling of Imines Templated by Chiral Diboron
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We herein report a general, practical, and highly efficient method for asymmetric synthesis of a wide range of chiral vicinal diamines via reductive coupling of imines templated by chiral diboron. The protocol features high enantioselectivity and stereospecificity, mild reaction conditions, simple operating procedures, use of readily available starting materials, and a broad substrate scope. The method signifies the generality of diboron-enabled [3,3]-sigmatropic rearrangement.
- Chen, Dongping,Li, Kaidi,Tang, Wenjun,Xu, Guangqing,Xu, Ronghua,Zhou, Mingkang
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supporting information
p. 10337 - 10342
(2020/07/04)
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- Diboron glycol ester as well as preparation method, intermediate and application thereof
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The invention discloses diboron glycol ester as well as a preparation method, an intermediate and application thereof. The diboron glycol ester can be used for inducing reductive coupling reaction with imine as a substrate, and the substrate can be obtained by reaction of aldehyde and ammonia and is very easy to obtain and quite low in cost. The product can be separated from a reaction system onlyby acid-base operation without column chromatography purification, and the post-treatment mode is convenient and easy to operate. The yield of the obtained product is high, and protective group operation is not needed. The diboron glycol ester has chirality, the stereoselectivity of the reductive coupling reaction is generally excellent, and 99% ee chiral diamine can be obtained only through simple recrystallization. The diboron glycol ester can be obtained by reacting diol with diboron glycol ester, the diol is convenient to prepare and easy to amplify, the diol can be recycled from a reaction solution through simple acid-base operation, the recovery rate reaches 95%, and the preparation cost is further saved.
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Paragraph 0130-0132; 0248-0252
(2020/08/02)
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- Enantioselective intramolecular C-H amination of aliphatic azides by dual ruthenium and phosphine catalysis
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The catalytic enantioselective intramolecular C(sp3)-H amination of aliphatic azides represents an efficient method for constructing chiral saturated cyclic amines which constitute a prominent structural motif in bioactive compounds. We report a dual catalytic system involving a chiral-at-metal bis(pyridyl-NHC) ruthenium complex and tris(4-fluorophenyl)phosphine (both 1 mol%), which facilitates the cyclization of aliphatic azides to chiral α-aryl pyrrolidines with enantioselectivities of up to 99% ee, including a pyrrolidine which can be converted to the anti-tumor alkaloid (R)-(+)-crispine. Mechanistically, the phosphine activates the organic azide to form an intermediate iminophosphorane and transfers the nitrene unit to the ruthenium providing an imido ruthenium intermediate which engages in the highly stereocontrolled C-H amination. This dual catalysis combines ruthenium catalysis with the Staudinger reaction and provides a novel strategy for catalyzing enantioselective C-H aminations of unactivated aliphatic azides.
- Qin, Jie,Zhou, Zijun,Cui, Tianjiao,Hemming, Marcel,Meggers, Eric
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p. 3202 - 3207
(2019/03/21)
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- Selective synthesis of mono- and di-methylated amines using methanol and sodium azide as C1 and N1 sources
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A Ru(ii) complex mediated synthesis of various N,N-dimethyl and N-monomethyl amines from organic azides using methanol as a methylating agent is reported. This methodology was successfully applied for a one-pot reaction of bromide derivatives and sodium azide in methanol. Notably, by controlling the reaction time several N-monomethylated and N,N-dimethylated amines were synthesized selectively. The practical applicability of this tandem process was revealed by preparative scale reactions with different organic azides and synthesis of an anti-vertigo drug betahistine. Several kinetic experiments and DFT studies were carried out to understand the mechanism of this transformation.
- Chakrabarti, Kaushik,Mishra, Anju,Panja, Dibyajyoti,Paul, Bhaskar,Kundu, Sabuj
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supporting information
p. 3339 - 3345
(2018/07/29)
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- Synthesis of benzimidazoles by Cul-catalyzed three-component reaction of 2-haloaniline, ammonia and aldehyde in water
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An efficient copper-catalyzed three-component reaction of 2-haloaniline, ammonia and aldehyde for the synthesis of benzimidazoles with 1,10-phenanthroline as the ligand has been developed. A variety of substituted benzimidazole derivatives can be obtained in yields up to 95%.
- Ke, Fang,Zhang, Peng,Lin, Chen,Lin, Xiaoyan,Xu, Jianhua,Zhou, Xiangge
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p. 8090 - 8094
(2018/11/23)
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- Microwave-Assisted Nickel-Catalyzed Synthesis of Benzimidazoles: Ammonia as a Cheap and Nontoxic Nitrogen Source
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An efficient and convenient Ni-catalyzed C-N bond formation for the synthesis of various benzimidazoles from various 2-haloanilines, aldehydes, and ammonia in a concise manner is reported. This protocol uses commercially available, nonhazardous, clean ammonia as a reaction partner instead of other nitrogen sources. Benzimidazoles, as the sole products, were obtained in high to excellent yields (up to 95%).
- Ke, Fang,Zhang, Peng,Xu, Yiwen,Lin, Xiaoyan,Lin, Jin,Lin, Chen,Xu, Jianhua
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p. 2722 - 2726
(2018/12/14)
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- Kinetic Resolution of Secondary Allyl Boronates and Their Application in the Synthesis of Homoallylic Amines
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Highly enantioenriched, chromatographically-stable secondary allyl boronates featuring a 1,1,2,2-tetraethyl-1,2-ethanediol fragment (Epin) were obtained by kinetic resolution of their racemic mixtures. The Epin group at boron considerably improved stability of allyl boronates allowing them to be readily isolated by chromatography on silica. The resolved reagents were applied in stereoselective synthesis of homoallylic amines with an internal double bond employing unprotected imines formed in situ from aldehydes and ammonia. The reactions proceeded with an excellent transfer of chirality.
- Villar, Laura,Orlov, Nikolai V.,Kondratyev, Nikolay S.,Uria, Uxue,Vicario, Jose L.,Malkov, Andrei V.
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supporting information
p. 16262 - 16265
(2018/10/20)
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- A practical oxidative conversion of aldehydes into N-chloroaldimines
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A novel method for the preparation of N-chloroaldimines from commonly available aromatic aldehydes has been developed. The reaction proceeded effectively by two steps: aldehydes were initially transformed into imines and then chloro-substitution with NaClO2 gave the N-chloroaldimines. This simple protocol allows for the preparation of a variety of aromatic N-chloroaldimines in moderate to excellent yields without the isolation of the imine intermediate. We also found that 3-nitrobenzaldehyde and 4-cyanobenzaldehyde were converted into the related benzonitrile directly under the standard conditions.
- Jin, Can,Wang, Feng,Sun, Bin,Zhuang, Xiaohui
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p. 547 - 551
(2018/11/27)
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- Redox reaction between benzyl azides and aryl azides: concerted synthesis of aryl nitriles and anilines
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A unique and novel reaction between benzyl azides and aryl azides is described to synthesize aryl nitriles and anilines concurrently, which is catalyzed with a photoactivated diruthenium complex. N-Unsubstituted imines (N-H imines) are generated first from benzyl azides, followed by the hydrogen transfer reaction between N-H imines and aryl azides. A wide range of aryl nitriles and anilines were synthesized under neutral and mild reaction conditions.
- Kim, Yongjin,Rhee, Young Ho,Park, Jaiwook
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supporting information
p. 1636 - 1641
(2017/02/23)
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- Selective Hydrogenation of Nitriles to Secondary Imines Catalyzed by an Iron Pincer Complex
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Selective hydrogenation of nitriles to secondary imines catalyzed by an iron complex, the pincer complex (iPr-PNP)Fe(H)Br(CO), in the presence of catalytic base, is reported. A wide range of (hetero)aromatic and aliphatic nitriles are hydrogenated to the corresponding secondary imines under mild conditions.
- Chakraborty, Subrata,Milstein, David
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p. 3968 - 3972
(2017/06/19)
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- A practical iodine-catalyzed oxidative conversion of aldehydes to nitriles
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A simple and efficient method for the direct synthesis of nitriles from aldehydes using ammonium acetate as the nitrogen source has been developed. The reactions were performed with iodine as the catalyst and tert-butyl hydroperoxide (TBHP) as the oxidant under mild conditions. A variety of aromatic, heteroaromatic, aliphatic and allylic aldehydes could be converted into their corresponding nitriles in good to excellent yields.
- Fang, Chaojie,Li, Meichao,Hu, Xinquan,Mo, Weimin,Hu, Baoxiang,Sun, Nan,Jin, Liqun,Shen, Zhenlu
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p. 1484 - 1489
(2017/01/21)
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- Mechanochemical Strecker Reaction: Access to α-Aminonitriles and Tetrahydroisoquinolines under Ball-Milling Conditions
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A mechanochemical version of the Strecker reaction for the synthesis of α-aminonitriles was developed. The milling of aldehydes, amines, and potassium cyanide in the presence of SiO2gave the corresponding α-aminonitriles in good to high yields. The high efficiency of the mechanochemical Strecker-type multicomponent reaction allowed the one-pot synthesis of tetrahydroisoquinolines after a subsequent internal N-alkylation reaction.
- Hernández, José G.,Turberg, Mathias,Schiffers, Ingo,Bolm, Carsten
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supporting information
p. 14513 - 14517
(2016/10/03)
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- One-pot reductive amination of carbonyl compounds with ammonia via ‘hydrogen borrowing’ using hydrido- and bis-ammine P,O(Me)-ruthenacycles
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The novel cationic [RuH{PPh2(2-OMeC6H4)}2]BPh4and neutral trans-[Ru(NH3)2{PPh2(2-OC6H4)}2] complexes were isolated from phosphine substitution reactions with [RuH(1,5-cod)(NH2NMe2)3]BPh4and [RuCl(1,5-cod)(NH3)2(NH2NMe2)]BPh4respectively. Ligand induced bisdemethylation of the pendent ether moieties of the phosphines occurred to give rise to the bis-phosphanylphenoxy moieties. Both complexes catalyzed the one-pot reductive amination of carbonyl compounds where excellent selectivity of aryl aldehydes over aryl ketones as precursors to the alcoholic species existed. Through substrate screening and1H NMR studies, both steric and electronic effects of the substrates were found to influence the hydrogenation/amination mechanistic pathway, as well as direct the alcohol:amine selectivity.
- Malan, Frederick P.,Noh, Ji-Hyang,Naganagowda, Gadada,Singleton, Eric,Meijboom, Reinout
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p. 139 - 145
(2016/11/18)
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- Graphene oxide as a metal-free catalyst for oxidation of primary amines to nitriles by hypochlorite
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Graphene oxide catalyzes oxidation by NaClO of primary benzyl and aliphatic amines to a product distribution comprising nitriles and imines. Nitriles are the sole product for long chain aliphatic amines. Spectroscopic characterization suggests that percarboxylic and perlactone groups could be the active sites of the process.
- Primo, Ana,Puche, Marta,Pavel, Octavian D.,Cojocaru, Bogdan,Tirsoaga, Alina,Parvulescu, Vasile,García, Hermenegildo
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p. 1839 - 1842
(2016/02/12)
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- Synthesis, photophysical and acidochromic properties of a series of tetrahydrodibenzo[a,i]phenanthridine chromophores
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A series of luminescent 5-aryl-tetrahydrodibenzo[a,i]phenanthridines was developed through modified synthetic protocol using SnCl2-acetic acid as a catalyst. The synthesis was consistent with various functionalities and significantly improves t
- Balijapalli, Umamahesh,Udayadasan, Sathiskumar,Shanmugam, Easwaramoorthi,Kulathu Iyer, Sathiyanarayanan
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p. 233 - 244
(2016/05/24)
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- Catalytic Manufacturing Method for Imine Having No Substituent Group on the Nitrogen, and Use for the Imine Produced
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The present invention relates to a method for manufacturing an imine having no substituent group on the nitrogen by using, as a catalyst, a metal complex on an organic azide compound, and more specifically relates to a method in which a metal-complex catalyst is used to produce, from an organic azide having an alpha-hydrogen, an imine having no substituent group on the nitrogen via a continuous nitrogen removal and 1,2-hydrogen transfer reaction. The imine having no substituent group on the nitrogen manufactured by means of the method of the present invention can synthesise diverse coupling products comprising amine compounds by means of reactions with diverse nucleophiles.
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Paragraph 0067-0070
(2015/12/23)
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- Factors influencing the regioselectivity of the oxidation of asymmetric secondary amines with singlet oxygen
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Aerobic amine oxidation is an attractive and elegant process for the α functionalization of amines. However, there are still several mechanistic uncertainties, particularly the factors governing the regioselectivity of the oxidation of asymmetric secondary amines and the oxidation rates of mixed primary amines. Herein, it is reported that singlet-oxygen-mediated oxidation of 1° and 2° amines is sensitive to the strength of the α-C-H bond and steric factors. Estimation of the relative bond dissociation energy by natural bond order analysis or by means of one-bond C-H coupling constants allowed the regioselectivity of secondary amine oxidations to be explained and predicted. In addition, the findings were utilized to synthesize highly regioselective substrates and perform selective amine cross-couplings to produce imines.
- Ushakov, Dmitry B.,Plutschack, Matthew B.,Gilmore, Kerry,Seeberger, Peter H.
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supporting information
p. 6528 - 6534
(2015/04/22)
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- PROCESS FOR PRODUCING AMIDE COMPOUNDS
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An efficient and eco-friendly process for producing amide compounds comprising contacting a primary amine with molecular oxygen-containing gas, solvent and ammonia solution in the presence of a non-precious metal-containing ordered, mesoporous solid catalyst is disclosed.
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Paragraph 0050; 0055
(2015/04/15)
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- Flexible synthesis of polyfunctionalised 3-fluoropyrroles
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An efficient and selective approach for the synthesis of polyfunctionalised 3-fluoropyrroles has been developed starting from commercial aldehydes. The methodology is concise, efficient and allows for the modular and systematic assembly of polysubstituted 3-fluoropyrroles. This synthesis provides an alternative and highly convergent strategy for the generation of these chemically and biologically important units.
- Cogswell, Thomas J.,Donald, Craig S.,Marquez, Rodolfo
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supporting information
p. 183 - 190
(2015/12/30)
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- C-H activation guided by aromatic N-H ketimines: Synthesis of functionalized isoquinolines using benzyl azides and alkynes
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Aromatic N-H ketimines were in situ generated from various benzylic azides by ruthenium catalysis for the subsequent Rh-catalyzed annulation reaction with alkynes to give the corresponding isoquinolines. In contrast to conventional synthetic methods for aromatic N-H ketimines, our protocol works under mild and neutral conditions, which enabled the synthesis of isoquinolines having various functionalities such as carbonyl, ester, alkenyl, and ether groups. In addition, the imidates generated from α-azido ethers were successfully used for the synthesis of 1-alkoxyisoquinolines.
- Gupta, Sreya,Han, Junghoon,Kim, Yongjin,Lee, Soon W.,Rhee, Young Ho,Park, Jaiwook
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p. 9094 - 9103
(2014/12/11)
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- Copper nanoparticles from copper aluminum hydrotalcite: An efficient catalyst for acceptor- and oxidant-free dehydrogenation of amines and alcohols
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An efficient and simple process for the preparation of stable nanocopper(0) on alumina [Cu(0)/Al2O3] from the inorganic composite precursor copper aluminum hydrotalcite (Cu-AlHT) by a chemical reduction method is described. Cu(0)/ Al2O3 was employed as an efficient catalyst in the acceptor- and oxidant-free dehydrogenation of various amines and alcohols to their corresponding dehydrogenated products in good to excellent yields. The stability of Cu(0)/Al2O3 was assessed by studying its recoverability and reusability in the dehydrogenation of amines and alcohols for up to five cycles.
- Damodara, Dandu,Arundhathi, Racha,Likhar, Pravin R.
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supporting information
p. 189 - 198
(2014/03/21)
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- Photocatalytic aerobic oxidation of amines to imines on BiVO4 under visible light irradiation
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BiVO4 was found to be an efficient photocatalyst under visible light irradiation for selective oxidation of amines to imines with high activity (99% conversion) and selectivity (up to 99%) using oxygen as an oxidant.
- Yuan, Bo,Chong, Ruifeng,Zhang, Bao,Li, Jun,Liu, Yan,Li, Can
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supporting information
p. 15593 - 15596
(2015/01/08)
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- Homogeneous hydrogenation of nitriles catalyzed by molybdenum and tungsten amides
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Low-valent molybdenum and tungsten amides M(NO)(CO)(PNP) {M = Mo, 1a; W, 1b; PNP = N(CH2CH2PiPr2) 2} were found to be active catalysts for the hydrogenation of various nitriles to the corresponding imines, primary amines, and N-substituted imines with high selectivity for the latter type of product. A wide range of p-and m-substituted aromatic nitriles-p-methyl, p-methoxy, p-bromobenzonitriles; 3-trifluoromethylbenzonitrile, m-and p-disubstituted benzonitrile; the heterocyclic 2-thiophencarbonitrile; and the aliphatic nitriles cyclohexylcarbonitrile and benzylcyanide-could be hydrogenated at 140 °C and 60 bar H2 in THF with high yields. TOFs were found to be between 0.4 and 36 h-1.
- Chakraborty, Subrata,Berke, Heinz
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p. 2191 - 2194
(2014/07/21)
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- Alcohol amination with ammonia catalyzed by an acridine-based ruthenium pincer complex: A mechanistic study
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The mechanistic course of the amination of alcohols with ammonia catalyzed by a structurally modified congener of Milstein's well-defined acridine-based PNP-pincer Ru complex has been investigated both experimentally and by DFT calculations. Several key Ru intermediates have been isolated and characterized. The detailed analysis of a series of possible catalytic pathways (e.g., with and without metal-ligand cooperation, inner- and outer-sphere mechanisms) leads us to conclude that the most favorable pathway for this catalyst does not require metal-ligand cooperation.
- Ye, Xuan,Plessow, Philipp N.,Brinks, Marion K.,Schelwies, Mathias,Schaub, Thomas,Rominger, Frank,Paciello, Rocco,Limbach, Michael,Hofmann, Peter
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supporting information
p. 5923 - 5929
(2014/05/20)
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- Continuous-flow oxidative cyanation of primary and secondary amines using singlet oxygen
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Primary and secondary amines can be rapidly and quantitatively oxidized to the corresponding imines by singlet oxygen. This reactive form of oxygen was produced using a variable-temperature continuous-flow LED-photoreactor with a catalytic amount of tetraphenylporphyrin as the sensitizer. α- Aminonitriles were obtained in good to excellent yields when trimethylsilyl cyanide served as an insitu imine trap. At 25°C, primary amines were found to undergo oxidative coupling prior to cyanide addition and yielded secondary α-aminonitriles. Primary α-aminonitriles were synthesized from the corresponding primary amines for the first time, by an oxidative Strecker reaction at -50 °C. This atom-economic and protecting-group-free pathway provides a route to racemic amino acids, which was exemplified by the synthesis of tert-leucine hydrochloride from neopentylamine. The mild synthesis of imines paves the way to aminonitriles and amino acids. Aerobic oxidation of primary and secondary amines in a continuous photoreactor with singlet oxygen generated insitu led to the rapid formation of imines, which were quantitatively trapped as α-aminonitriles (see scheme; TMS=trimethylsilyl). Benzylic and primary α-aminonitriles, precursors for amino acids, could be efficiently produced in three minutes.
- Ushakov, Dmitry B.,Gilmore, Kerry,Kopetzki, Daniel,McQuade, D. Tyler,Seeberger, Peter H.
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supporting information
p. 557 - 561
(2014/01/23)
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- Metal-free, one-pot oxidative conversion of aldehydes to primary thioamides in aqueous media
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One-pot tandem reactions of a variety of aldehydes with aqueous ammonia, molecular iodine, and O,O-diethyl dithiophosphoric acid readily afford the corresponding primary thioamides. This is an inexpensive, practical, and metal-free way of accessing various thioamides from aldehydes in aqueous media. The pure products are obtained simply by filtration followed by successive washing with aqueous sodium thiosulfate and water. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Yadav, Arvind K.,Srivastava, Vishnu P.,Yadav, Lal Dhar S.
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supporting information
p. 408 - 416
(2014/01/06)
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- New reactions of N-tert-butylimines; Formation of N-heterocycles by methyl radical elimination on flash vacuum thermolysis of N-benzylidene- and N-(2-pyridylmethylidene)-tert-butylamines
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Thermal reactions of N-benzylidene- and N-(2-pyridylmethylidene)-tert- butylamines (5 and 13) under FVT conditions have been investigated. Unexpectedly, at 800 °C, compound 5 yields 1,2-dimethylindole and 3-methylisoquinoline. In the reaction of 13 at 800 °C, 3-methylimidazo[1,5- a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV-photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ. Copyright
- Vu, Thien Y,Chrostowska, Anna,Huynh, Thi Kieu Xuan,Khayar, Said,Dargelos, Alain,Justyna, Katarzyna,Pasternak, Beata,Lesniak, Stanislaw,Wentrup, Curt
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supporting information
p. 14983 - 14988
(2013/11/06)
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- Ruthenium-catalyzed redox-neutral and single-step amide synthesis from alcohol and nitrile with complete atom economy
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A completely atom-economical and redox-neutral catalytic amide synthesis from an alcohol and a nitrile is realized. The amide C-N bond is efficiently formed between the nitrogen atom of nitrile and the α-carbon of alcohol, with the help of an N-heterocyclic carbene-based ruthenium catalyst, without a single byproduct. A utility of the reaction was demonstrated by synthesizing 13C or 15N isotope-labeled amides without involvement of any separate reduction and oxidation step.
- Kang, Byungjoon,Fu, Zhenqian,Hong, Soon Hyeok
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supporting information
p. 11704 - 11707
(2013/09/02)
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- Selective gas-phase hydrogenation of benzonitrile into benzylamine over Cu-MgO catalysts without using any additives
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A clean and mild gas-phase hydrogenation of benzonitrile to benzylamine has been accomplished using Cu-MgO catalysts prepared by impregnating a freshly prepared MgO support using Cu(NO3)2·3H2O as a Cu precursor with Cu loading of 4, 8, 12 and 16%, of which 12% Cu-MgO catalyst exhibited superior activity with 98% conversion of benzonitrile and 70% selectivity of benzylamine even in the absence of any additives at atmospheric pressure. Under these optimized conditions, the selectivity of benzylamine has been significantly elevated to nearly 100% with considerable conversion.
- Marella, Ravi Kumar,Koppadi, Kumara Swamy,Jyothi, Yadagiri,Rama Rao, Kamaraju Seetha,Burri, David Raju
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p. 3229 - 3235
(2013/10/01)
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- PROCESS FOR PRODUCING AMIDE COMPOUNDS
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An efficient and eco-friendly process for producing amide compounds comprising contacting a primary amine with molecular oxygen-containing gas, solvent and ammonia solution in the presence of a non-precious metal-containing ordered, mesoporous solid catalyst is disclosed.
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Page/Page column 11; 12
(2013/09/12)
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- Characterization and utility of N-unsubstituted imines synthesized from alkyl azides by ruthenium catalysis
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Shine a light: A fluorescent light-induced synthetic method for the title compounds has been developed and the chemoselective nature of the reaction is highlighted by the observation of the cis/trans isomers of various N-unsubstituted imines. The synthetic utility of this method is demonstrated by the one-pot imine formation/asymmetric allylation sequence of benzyl azide catalyzed by 1. (Ipc=isopinocampheyl). Copyright
- Lee, Jin Hee,Gupta, Sreya,Jeong, Wook,Rhee, Young Ho,Park, Jaiwook
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supporting information
p. 10851 - 10855
(2013/01/15)
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- Initiators based on benzaldoximes: Bimolecular and covalently bound systems
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Typical bimolecular photoinitiators (PIs) for radical polymerization of acrylates show only poor photoreactivity because of the undesired effect of back electron transfer. To overcome this limitation, PIs consisting of a benzaldoxime ester and various sensitizers based on aromatic ketones were introduced. The core of the photoinduced reactivity was established by laser flash photolysis, photo-CIDNP, and EPR experiments at short time scales. According to these results, the primarily formed iminyl radicals are not particularly active. The polymerization is predominantly initiated by C-centered radicals. Photo-DSC experiments show reactivities comparable to that of classical monomolecular type I PIs like Darocur 1173.
- Griesser, Markus,Rosspeintner, Arnulf,Dworak, Claudia,Hoefer, Michael,Grabner, Gottfried,Liska, Robert,Gescheidt, Georg
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p. 8648 - 8657
(2013/01/15)
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- Selective synthesis of secondary amines by Pt nanowire catalyzed reductive amination of aldehydes and ketones with ammonia
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The process of the reductive amination of aldehydes or ketones in the presence of ammonia using unsupported ultra-thin Pt nanowires has been developed. This catalytic system shows high activity and selectivity under mild reaction conditions.
- Qi, Fenqiang,Hu, Lei,Lu, Shuanglong,Cao, Xueqin,Gu, Hongwei
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p. 9631 - 9633
(2012/10/29)
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- Inhibitors of Serine Proteases
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The present invention relates to compounds that inhibit serine protease activity, particularly the activity of hepatitis C virus NS3-NS4A protease. As such, they act by interfering with the life cycle of the hepatitis C virus and are also useful as antiviral agents. The invention further relates to compositions comprising these compounds either for ex vivo use or for administration to a patient suffering from HCV infection. The invention also relates to methods of treating an HCV infection in a patient by administering a composition comprising a compound of this invention.
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- Solvent-and catalyst-free reaction of (aminomethyl)phosphonates with epoxides: Synthesis of novel {[(2-hydroxyethyl)amino]methyl}phosphonates
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Uncatalyzed reaction of epoxides with (aminomethyl)phosphonates for the synthesis of novel {[(2-hydroxyethyl)amino]methyl}phosphonates is described. Treatment of (aminomethyl)phosphonates with epoxides without any catalyst and under solvent-free condition
- Kaboudin, Babak,Sorbiun, Mina
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experimental part
p. 284 - 289
(2011/04/12)
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- Imine allylation using 2-alkoxycarbonyl allylboronates as an expedient three-component reaction to polysubstituted α-exo-methylene-γ-lactams
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α-exo-Methylene-γ-lactams are key structural units in a wide variety of biologically active natural products. A concise route to the formation of polysubstituted α-exo-methylene-γ-lactams is described. In this three-component reaction, an imine is formed
- Elford, Tim G.,Hall, Dennis G.
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body text
p. 6995 - 6998
(2009/04/10)
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