- N,N-Chelate nickel(II) complexes bearing Schiff base ligands as efficient hydrogenation catalysts for amine synthesis
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Five N, N-chelate nickel (II) complexes bearing N-(2-pyridinylmethylene)-benzylamine ligands with different substituent groups were synthesized in good yields. The nickel complexes exhibited prominent catalytic efficiency toward amine synthesis from nitro compounds by using NaBH4 or H2 as hydrogen source through two catalytic systems. Various amines with different substituents were obtained in moderate to excellent yields. All substrates with electron-donating and electron-withdrawing properties were tolerated in the two reduction systems. Given the efficient catalytic activity, broad substance scope, and mild reduction conditions, the nickel catalysts have potential applications in industrial production.
- Xu, Mengyin,Wang, Yang,Zhou, Yifeng,Yao, Zi-Jian
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- Synthesis, characterization, and antimicrobial studies of half-sandwich η6-toluene ruthenium complexes with N,N′-bidentate ligands
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Nine new complexes [(η6-C6H5-CH3)RuLCl]+(PF6)ˉ (where L = N,N′-bidentate ligand; (C5H4NCH = N-Ar) where Ar = 4-methylphenyl (C20H20ClF6N2PRu, 1); 3,4-dimethylphenyl (C21H22ClF6N2PRu, 2); 2,4,6-trimethylphenyl (C21H24ClF6N2PRu, 3); 4-bromophenyl (C19H17ClBrF6N2PRu, 4); 2,5-dimethylphenyl (C21H22ClF6N2PRu, 5); 2-flourophenyl (C19H17ClF7N2PRu, 6), (4-methoxyphenyl)methylene (C21H22ClF6N2OPRu, 7); phenylmethylene (C20H20ClF6N2PRu, 8); and 3,5-dimethylphenyl (C21H22ClF6N2PRu, 9) were synthesized by reacting the corresponding N,N′-bidentate ligands with the ruthenium arene dimer in a 2:1 ratio. The compounds were fully characterized via 1H NMR and 13C NMR, IR, and UV-vis spectroscopy and elemental analyses. The molecular structures of representative complexes (1, 7, and 8) were established by single-crystal X-ray diffraction studies. In the molecular structures of the complexes, the ligands coordinate to the Ru(II) centers via the pyridine nitrogen atom and the imine N atom in a bidentate manner. The other coordination sites of the Ru(II) center are occupied by the tolyl system in an η6 manner resulting in geometry often referred to as “pseudo-octahedral piano-stool.” All compounds were evaluated for their in?vitro antibacterial activity by the disk diffusion method against a panel of Gram-negative and Gram-positive bacteria. The complexes showed promising bactericidal activity against methicillin-resistant Staphylococcus aureus ATCC 43300.
- Gichumbi, Joel M.,Friedrich, Holger B.,Omondi, Bernard,Chenia, Hafizah Y.
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p. 1833 - 1847
(2020/08/05)
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- Diastereoselective Control of Tetraphenylethene Reactivity by Metal Template Self-Assembly
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The reaction of 4,4′,4′′,4′′′-(ethene-1,1,2,2-tetrayl)tetraaniline with 2-pyridinecarboxaldehyde and iron(II) chloride resulted, after aqueous workup, in the diastereoselective formation of an [Fe2L3]4+ triple-stranded hel
- Kennedy, Aaron D. W.,de Haas, Nicholas,Iranmanesh, Hasti,Luis, Ena T.,Shen, Chao,Wang, Pi,Price, Jason R.,Donald, William A.,Andréasson, Joakim,Huang, Feihe,Beves, Jonathon E.
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supporting information
p. 5708 - 5718
(2019/04/03)
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- Ruthenium-cymene containing pyridine-derived aldiimine ligands: Synthesis, characterization and application in the transfer hydrogenation of aryl ketones and kinetics studies
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Five electron-rich N[sbnd]N′?pyridylimine ligands, which form five-membered chelate ring when coordinate to a metal center, have been synthesized by the easily accessible condensation between 2-pyridinecarboxyaldhehyde and the corresponding substituted an
- Ramos, Thiago S.,Luz, Diego M.,Nascimento, Rebecca D.,Silva, Andressa K.,Li?o, Luciano M.,Miranda, Victor M.,Deflon, Victor M.,de Araujo, Márcio P.,Ueno, Leonardo T.,Machado, Francisco B.C.,Dinelli, Luís R.,Bogado, André L.
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- Experimental and mechanistic insights into copper(ii)-dioxygen catalyzed oxidative: N -dealkylation of N -(2-pyridylmethyl)phenylamine and its derivatives
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A di-(2-pyridylmethyl)phenylamine ((PyCH2)2NPh) supported Cu(ii)/O2 catalytic system was explored with the synthesis of pyridylmethyl-based compounds of carboxylate (PyCOOH), amide (PyC(O)NHPh), and imine (PyCHNPh) from the oxidative N-dealkylation of N-(2-pyridylmethyl)phenylamine (PyCH2NHPh) and its derivatives, by means of controlling the addition of a base and/or water to the reaction system under a dioxygen atmosphere at room temperature. Experimental studies showed that the imine and amide species could be precursors in succession in the way to the final oxidation state of carboxylates. A cyclic catalytic mechanism was proposed including the base triggered C-H bond activation of the 2-pyridylmethyl group (PyCH2-) and the intermolecular Cu-OOH α-hydrogen atom abstraction from the coordinated imine substrate (PyCHNPh).
- Wang, Yang,Liu, Haixiong,Zhang, Xiaofeng,Zhang, Zilong,Huang, Deguang
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p. 9164 - 9168
(2017/11/15)
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- Quantitative Reactivity Scales for Dynamic Covalent and Systems Chemistry
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Dynamic covalent chemistry (DCC) has become a powerful tool for the creation of molecular assemblies and complex systems in chemistry and materials science. Herein we developed for the first time quantitative reactivity scales capable of correlation and prediction of the equilibrium of dynamic covalent reactions (DCRs). The reference reactions are based upon universal DCRs between imines, one of the most utilized structural motifs in DCC, and a series of O-, N-, and S- mononucleophiles. Aromatic imines derived from pyridine-2-carboxyaldehyde exhibit capability for controlling the equilibrium through distinct substituent effects. Electron-donating groups (EDGs) stabilize the imine through quinoidal resonance, while electron-withdrawing groups (EWGs) stabilize the adduct by enhancing intramolecular hydrogen bonding, resulting in curvature in Hammett analysis. Notably, unique nonlinearity induced by both EDGs and EWGs emerged in Hammett plot when cyclic secondary amines were used. This is the first time such a behavior is observed in a thermodynamically controlled system, to the best of our knowledge. Unified quantitative reactivity scales were proposed for DCC and defined by the correlation log K = SN (RN + RE). Nucleophilicity parameters (RN and SN) and electrophilicity parameters (RE) were then developed from DCRs discovered. Furthermore, the predictive power of those parameters was verified by successful correlation of other DCRs, validating our reactivity scales as a general and useful tool for the evaluation and modeling of DCRs. The reactivity parameters proposed here should be complementary to well-established kinetics based parameters and find applications in many aspects, such as DCR discovery, bioconjugation, and catalysis.
- Zhou, Yuntao,Li, Lijie,Ye, Hebo,Zhang, Ling,You, Lei
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supporting information
p. 381 - 389
(2016/01/26)
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- Dual Role of Acetate in Copper(II) Acetate Catalyzed Dehydrogenation of Chelating Aromatic Secondary Amines: A Kinetic Case Study of Copper-Catalyzed Oxidation Reactions
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Copper(II) acetate is a frequent empirical choice of the copper source in copper(II)-mediated redox reactions. The effect of the acetate counterion appears crucial but has not been adequately investigated. Herein, we report that copper(II) acetate catalyz
- Sreenath, Kesavapillai,Yuan, Zhao,Macias-Contreras, Miguel,Ramachandran, Vasanth,Clark, Ronald J.,Zhu, Lei
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supporting information
p. 3728 - 3743
(2016/08/19)
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- Palladium(II) complexes with N,N′-bidentate N-methyl-N-(pyridin-2-ylmethyl)aniline and its derivatives: Synthesis, characterization, and methyl methacrylate polymerization
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The N,N′-bidentate [(N,N′)PdCl2] complexes [i.e., [LnPdCl2] (Ln = L1-L5)] were synthesized by the reaction of [Pd(CH3CN)2Cl2] with N-methyl-N-(pyridin-2-ylmethyl)aniline (L1) and its derivatives (L2-L5) in ethanol. The molecular structures of [LnPdCl2] (Ln = L1-L3) were characterized using X-ray crystallography, which showed that the Pd atom in the Pd(II) complexes had a square planar geometry involving two nitrogen atoms of N,N′-bidentate and two chlorido ligands. The complexes [LnPdCl2] (Ln = L1-L5) were investigated for methyl methacrylate (MMA) polymerization in the presence of modified methylaluminoxane (MMAO) at 60°C. Specifically, complex [L1PdCl2] showed moderate catalytic activity toward MMA polymerization with an activity of 3.03 × 104 g poly(methylmethacrylate) (PMMA)/mol Pd·h and PMMA syndiotacticity (characterized by 1H NMR spectroscopy) of ~0.68.
- Kim, Sunghoon,Song, Yujin,Lee, Ha-Jin,Jeon, Jongho,Park, Sang Hyun,Lee, Hyosun
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p. 609 - 617
(2015/05/05)
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- Dynamic aminal-based TPA ligands
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The use of dynamic covalent reactions (DCRs) is gaining popularity for the construction of self-assembling architectures. We have recently introduced DCRs that exchange alcohols and aldehydes to create hemiaminal ethers within tri(2-picolyl)amine (TPA) li
- Zhou, Yuntao,Yuan, Yaofeng,You, Lei,Anslyn, Eric V.
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supporting information
p. 8207 - 8213
(2015/05/27)
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- Chloro-ruthenium complexes with carbonyl and N-(aryl)pyridine-2-aldimines as ancillary ligands. Synthesis, characterization and catalytic application in C-C cross-coupling of arylaldehydes with arylboronic acids
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Reaction of N-(aryl)pyridine-2-aldimines (L-R, R = OCH3, CH 3, H, Cl and NO2) with [Ru(CO)2Cl 2]n in refluxing ethanol affords a group of complexes of type [Ru(L-R)(CO)2Cl2]. In these complexes the diimine ligands (L-R) are coordinated to the metal center as NN-donors forming five-membered chelate rings, the carbonyls are mutually cis and the two chlorides are trans. Crystal structure of [Ru(L-OCH3)(CO) 2Cl2] has been determined. All the complexes show characteristic 1H NMR signals, and in dichloromethane solution they display intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows an irreversible oxidation of the metal center within 1.15-1.23 V vs SCE, and reduction(s) of the diimine ligand within -0.70 to -0.96 V vs SCE. The [Ru(L-R)(CO)2Cl2] complexes efficiently catalyze cross-coupling of arylaldehydes with arylboronic acids yielding diaryl ketones.
- Dey, Bikash Kali,Dutta, Jayita,Drew, Michael G.B.,Bhattacharya, Samaresh
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p. 176 - 184
(2014/01/06)
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- Synthesis of di-nitrogen Schiff base complexes of methyltrioxorhenium(VII) and their application in epoxidation with aqueous hydrogen peroxide as oxidant
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Several di-nitrogen Schiff bases were synthesized through the condensation of 2-pyridinecarboxaldehyde with primary amines. The Schiff bases as ligands coordinated with methyltrioxorhenium (MTO) smoothly to afford the correspondent complexes which were characterized by IR, 1H NMR, 13C NMR, MS and elemental analysis. One of the complexes was analyzed by X-ray crystallography as well. The results revealed that the complexes display distorted octahedral geometry in the solid state with a trans-position of Schiff base. Catalytic results indicated that the complexes as catalysts increased the selectivity of epoxides remarkably compared with MTO in the epoxidation of alkenes with 30% hydrogen peroxide as oxidant and the increasing rate depended on the structure of the Schiff base ligands of the complexes. The results indicated that the stronger the donating ability of the ligand, the higher selectivity of epoxides the complex gave in the epoxidation of alkenes with 30% hydrogen peroxide as oxidant. Copyright
- Gao, Yu,Zhang, Yuecheng,Qiu, Chuanjiang,Zhao, Jiquan
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scheme or table
p. 54 - 60
(2011/09/16)
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- Synthesis and electrochemical studies of nickel -diketonate complexes incorporating asymmetric diimine ligands
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The reaction of ppaX {(4-X-phenyl)-pyridin-2-ylmethylene-amine; X = H, Me, Et, OMe, F, Cl, Br, and I} with [Ni(β-diketonate) 2(H2O)2] {β-diketonate = 1,3-diphenylpropanedionate (dbm), 2,2,6,6-tetramethyl-3,5-hep
- Harding, Phimphaka,Harding, David J.,Soponrat, Nitisastr,Tinpun, Kittiya,Samuadnuan, Sirirat,Adams, Harry
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experimental part
p. 75 - 82
(2010/05/18)
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- Multicomponent reaction of imidazo[1,5- a ]pyridine carbenes with aldehydes and dimethyl acetylenedicarboxylate or allenoates: A straightforward approach to fully substituted furans
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The facile three-component reactions of N,N-substituted imidazo[1,5-a]pyridine carbenes, namely imidazo[1,5-a]pyridin-3-ylidenes, with aldehydes and DMAD or allenoates were disclosed. Both reactions proceeded via tandem nucleophilic addition, [3 + 2]-cycloaddition, and ring transformation to produce different 4-[(2-pyridyl)methyl]aminofuran derivatives generally in moderate yields. This work not only 'rovided the first example of the application of imidazo[1,5-a]pyridin-3-ylidenes in organic synthesis but also developed a straightforward approach to fully substituted furans that are not easily accessible by other methods.
- Pan, Huan-Rui,Li, Yong-Jia,Yan, Cai-Xia,Xing, Juan,Cheng, Ying
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supporting information; experimental part
p. 6644 - 6652
(2010/11/17)
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- 4-N-aryl(benzyl)amino-4-hetaryl-1-butenes as building blocks in heterocyclic synthesis. 1. New route to 4,6-dimethyl-2-pyridylquinolines from the 4-N-p-methylphenylamino-4-pyridyl-1-butenes
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Mediated-acid intramolecular cyclisation of 4-N-p-methylphenylamino-4-pyridyl-1-butenes 4-6 was used to obtain new C-2 pyridyl substituted 4,6-dimethyl-1,2,3,4-tetrahydroquinolines 7-9, which were oxidised then to their aromatic analogues 10-12 in good yi
- Vargas Mendez, Leonor Y.,Kouznetsov, Vladimir,Stashenko, Elena,Bahsas, Al,Amaro-Luis, Juan
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p. 323 - 326
(2007/10/03)
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