77 results on '"Attila Bényei"'
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2. 'Inverted' Cyclic(Alkyl)(Amino)Carbene (CAAC) Ruthenium Complex Catalyzed Isomerization Metathesis (ISOMET) of Long Chain Olefins to Propylene at Low Ethylene Pressure
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Vajk Farkas, Dániel Csókás, Ádám Erdélyi, Gábor Turczel, Attila Bényei, Tibor Nagy, Sándor Kéki, Imre Pápai, and Róbert Tuba
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inverted CAAC ,ISOMET ,metathesis ,propylene ,ruthenium ,Science - Abstract
Abstract Isomerization Metathesis (ISOMET) reaction is an emerging tool for “open loop” chemical recycling of polyethylene to propylene. Novel, latent N‐Alkyl substituted Cyclic(Alkyl)(Amino)Carbene (CAAC)–ruthenium catalysts (5a‐Ru, 3b‐Ru – 6c‐Ru) are developed rendering “inverted” chemical structure while showing enhanced ISOMET activity in combination with (RuHCl)(CO)(PPh3)3 (RuH) double bond isomerization co‐catalyst. Systematic investigations reveal that the steric hindrance of the substituents on nitrogen and carbon atom adjacent to carbene moiety in the CAAC ligand have significantly improved the catalytic activity and robustness. In contrast to the NHC‐Ru and CAAC‐Ru catalyst systems known so far, these systems show higher isomerization metathesis (ISOMET) activity (TON: 7400) on the model compound 1‐octadecene at as low as 3.0 bar optimized pressure, using technical grade (3.0) ethylene. The propylene content formed in the gas phase can reach up to 20% by volume. more...
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- 2024
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3. Half-Sandwich Type Platinum-Group Metal Complexes of C-Glucosaminyl Azines: Synthesis and Antineoplastic and Antimicrobial Activities
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István Kacsir, Adrienn Sipos, Evelin Major, Nikolett Bajusz, Attila Bényei, Péter Buglyó, László Somsák, Gábor Kardos, Péter Bai, and Éva Bokor
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ruthenium ,osmium ,iridium ,rhodium ,half-sandwich complex ,C-glucosaminyl heterocycles ,Organic chemistry ,QD241-441 - Abstract
While platinum-based compounds such as cisplatin form the backbone of chemotherapy, the use of these compounds is limited by resistance and toxicity, driving the development of novel complexes with cytostatic properties. In this study, we synthesized a set of half-sandwich complexes of platinum-group metal ions (Ru(II), Os(II), Ir(III) and Rh(III)) with an N,N-bidentate ligand comprising a C-glucosaminyl group and a heterocycle, such as pyridine, pyridazine, pyrimidine, pyrazine or quinoline. The sugar-containing ligands themselves are unknown compounds and were obtained by nucleophilic additions of lithiated heterocycles to O-perbenzylated 2-nitro-glucal. Reduction of the adducts and, where necessary, subsequent protecting group manipulations furnished the above C-glucosaminyl heterocycles in their O-perbenzylated, O-perbenzoylated and O-unprotected forms. The derived complexes were tested on A2780 ovarian cancer cells. Pyridine, pyrazine and pyridazine-containing complexes proved to be cytostatic and cytotoxic on A2780 cells, while pyrimidine and quinoline derivatives were inactive. The best complexes contained pyridine as the heterocycle. The metal ion with polyhapto arene/arenyl moiety also impacted on the biological activity of the complexes. Ruthenium complexes with p-cymene and iridium complexes with Cp* had the best performance in ovarian cancer cells, followed by osmium complexes with p-cymene and rhodium complexes with Cp*. Finally, the chemical nature of the protective groups on the hydroxyl groups of the carbohydrate moiety were also key determinants of bioactivity; in particular, O-benzyl groups were superior to O-benzoyl groups. The IC50 values of the complexes were in the low micromolar range, and, importantly, the complexes were less active against primary, untransformed human dermal fibroblasts; however, the anticipated therapeutic window is narrow. The bioactive complexes exerted cytostasis on a set of carcinomas such as cell models of glioblastoma, as well as breast and pancreatic cancers. Furthermore, the same complexes exhibited bacteriostatic properties against multiresistant Gram-positive Staphylococcus aureus and Enterococcus clinical isolates in the low micromolar range. more...
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- 2023
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4. Synthesis of Multifunctional Aryl(trifloxyalkenyl)iodonium Triflate Salts
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Balázs L. Tóth, Ferenc Béke, Orsolya Egyed, Attila Bényei, András Stirling, and Zoltán Novák
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Chemistry ,QD1-999 - Published
- 2019
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5. Investigation of the Drug Carrier Properties of Insoluble Cyclodextrin Polymer Microspheres
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Ádám Haimhoffer, Alexandra Vas, Gabriella Árvai, Éva Fenyvesi, László Jicsinszky, István Budai, Attila Bényei, Géza Regdon, Ágnes Rusznyák, Gábor Vasvári, Judit Váradi, Ildikó Bácskay, Miklós Vecsernyés, and Ferenc Fenyvesi more...
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insoluble cyclodextrin polymer ,cyclodextrin beads ,curcumin ,estradiol-glow ,complexation ,drug delivery ,Microbiology ,QR1-502 - Abstract
The investigation of the usability of solid insoluble β-cyclodextrin polymers (βCDP) in micro-sized, controlled drug delivery systems has only recently attracted interest. Our aim was to form complexes with poorly soluble active pharmaceutical ingredients (APIs) with two types of βCDP for drug delivery applications. Solid insoluble cyclodextrin polymer of irregular shape (βCDPIS) and cyclodextrin microbeads (βCDPB) were used in the experiments. Morphology, surface area, size distribution and swelling capacity of carriers were investigated. We created complexes with two APIs, curcumin and estradiol, and applied powder X-ray diffraction, FTIR and thermal analysis (TGA/DSC) to prove the complexation. Finally, the dissolution, biocompatibility and permeation of APIs on Caco-2 cells were investigated. The size of the beads was larger than 100 µm, their shape was spherical and surfaces were smooth; while the βCDPIS particles were around 4 µm with irregular shape and surface. None of the polymers showed any cytotoxic effect on Caco-2 cells. Both carriers were able to extract curcumin and estradiol from aqueous solutions, and the dissolution test showed prolonged estradiol release. Caco-2 permeability tests were in accordance with the complexation abilities and dissolution of the complexes. This study offers useful data for further pharmaceutical applications of insoluble cyclodextrin polymers. more...
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- 2022
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6. Highly Selective Synthesis of 6-Glyoxylamidoquinoline Derivatives via Palladium-Catalyzed Aminocarbonylation
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Sami Chniti, László Kollár, Attila Bényei, and Attila Takács
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double carbonylation ,palladium ,aminocarbonylation ,6-iodoquinoline ,carbon monoxide ,Organic chemistry ,QD241-441 - Abstract
The aminocarbonylation of 6-iodoquinoline has been investigated in the presence of large series of amine nucleophiles, providing an efficient synthetic route for producing various quinoline-6-carboxamide and quinoline-6-glyoxylamide derivatives. It was shown, after detailed optimization study, that the formation of amides and ketoamides is strongly influenced by the reaction conditions. Performing the reactions at 40 bar of carbon monoxide pressure in the presence of Pd(OAc)2/2 PPh3, the corresponding 2-ketocarboxamides were formed as major products (up to 63%). When the monodentate triphenylphosphine was replaced by the bidentate XantPhos, the quinoline-6-carboxamide derivatives were synthesized almost exclusively under atmospheric conditions (up to 98%). The isolation and characterization of the new carbonylated products of various structures were also accomplished. Furthermore, the structure of three new mono- and double-carbonylated compounds were unambiguously established by using a single-crystal XRD study. more...
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- 2021
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7. Syntheses and Study of a Pyrroline Nitroxide Condensed Phospholene Oxide and a Pyrroline Nitroxide Attached Diphenylphosphine
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Mostafa Isbera, Balázs Bognár, Ferenc Gallyas, Attila Bényei, József Jekő, and Tamás Kálai
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lithiation ,McCormac reaction ,nitroxides ,protecting groups ,reduction ,Organic chemistry ,QD241-441 - Abstract
The reaction of a diene nitroxide precursor with dichlorophenylphosphine in a McCormac procedure afforded 1,1,3,3-tetramethyl-5-phenyl-1,2,3,4,5,6-hexahydrophospholo[3,4-c]pyrrole-5-oxide-2-oxyl. Lithiation of the protected 3-iodo-pyrroline nitroxide followed by treatment with chlorodiphenylphosphine after deprotection afforded (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine oxide, and after reduction, (1-oxyl-2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-3-yl)diphenylphosphine was realized, which was also supported by X-ray single crystal diffraction measurements. This pyrroline diphenylphosphine derivative was converted to hexadecylphosphonium salt, which is an analogue of antineoplastic agent, MITO-CP. more...
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- 2021
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8. Synthesis and HPLC-ECD Study of Cytostatic Condensed O,N-Heterocycles Obtained from 3-Aminoflavanones
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Ádám Szappanos, Attila Mándi, Katalin Gulácsi, Erika Lisztes, Balázs István Tóth, Tamás Bíró, Anita Kónya-Ábrahám, Attila Kiss-Szikszai, Attila Bényei, Sándor Antus, and Tibor Kurtán
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neber rearrangement ,3-aminoflavanones ,antiproliferative activity ,TDDFT-ECD calculations ,HPLC-ECD ,3-(N-chloroacetylamino)-flavan-4-ol ,Microbiology ,QR1-502 - Abstract
Racemic chiral O,N-heterocycles containing 2-arylchroman or 2-aryl-2H-chromene subunit condensed with morpholine, thiazole, or pyrrole moieties at the C-3-C-4 bond were synthesized with various substitution patterns of the aryl group by the cyclization of cis- or trans-3-aminoflavanone analogues. The 3-aminoflavanone precursors were obtained in a Neber rearrangement of oxime tosylates of flavanones, which provided the trans diastereomer as the major product and enabled the isolation of both the cis- and trans-diastereomers. The cis- and trans-aminoflavanones were utilized to prepare three diastereomers of 5-aryl-chromeno[4,3-b][1,4]oxazines. Antiproliferative activity of the condensed heterocycles and precursors was evaluated against A2780 and WM35 cancer cell lines. For a 3-(N-chloroacetylamino)-flavan-4-ol derivative, showing structural analogy with acyclic acid ceramidase inhibitors, 0.15 μM, 3.50 μM, and 6.06 μM IC50 values were measured against A2780, WM35, and HaCat cell lines, and apoptotic mechanism was confirmed. Low micromolar IC50 values down to 2.14 μM were identified for the thiazole- and pyrrole-condensed 2H-chromene derivatives. Enantiomers of the condensed heterocycles were separated by HPLC using chiral stationary phase, HPLC-ECD spectra were recorded and TDDFT-ECD calculations were performed to determine the absolute configuration and solution conformation. Characteristic ECD transitions of the separated enantiomers were correlated with the absolute configuration and effect of substitution pattern on the HPLC elution order was determined. more...
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- 2020
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9. Phosphine(III)‐Triggered One‐Pot Domino Sequences towards 5,6‐Dihydropyridine‐2‐(1 H )‐One and Pyridine‐2(1 H )‐One Scaffolds
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Zsófia Makra, Ramóna Madácsi, Tamás A. Martinek, Attila Bényei, László G. Puskás, Márió Gyuris, and Iván Kanizsai
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03.01. Általános orvostudomány ,General Chemistry - Published
- 2022
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10. Effect of Molecular Weight on the Dissolution Profiles of PEG Solid Dispersions Containing Ketoprofen
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Ha Pham Le Khanh, Ádám Haimhoffer, Dániel Nemes, Liza Józsa, Gábor Vasvári, István Budai, Attila Bényei, Zoltán Ujhelyi, Pálma Fehér, and Ildikó Bácskay
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Polymers and Plastics ,General Chemistry ,solid dispersion ,polyethylene glycol ,PEG ,ketoprofen ,solubility ,dissolution - Abstract
Solid dispersions are typically binary systems with a hydrophilic matrix polymer and a lipophilic active substance. During formulation, the drug undergoes a crystalline to amorphous phase transition, which leads to a supersaturated solution providing enhanced bioavailability. The interaction of the active substance and the polymer is unique and influences the level of supersaturation. We aimed to investigate the relationship between low molecular weight polyethylene glycol derivates PEG 1000, 1500, and 2000 and ketoprofen regarding the effect of molecular weight. The physicochemical properties of solid dispersions prepared with hot melt homogenization and their respective physical mixtures were investigated with Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy techniques. A phase solubility study was carried out in hydrochloric acid media which showed no difference between the three polymers, but the dissolution curves differed considerably. PEG 1000 had higher percentage of released drug than PEG 1500 and 2000, which had similar results. These results indicate that when multiple low molecular weight PEGs are suitable as matrix polymers of solid dispersions, the molecular weight has only limited impact on physicochemical characteristics and interactions and further investigation is needed to select the most applicable candidate. more...
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- 2023
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11. Highly Chemoselective One‐Step Synthesis of Novel N ‐Substituted‐Pyrrolo[3,4‐b]quinoline‐1,3‐diones via Palladium‐Catalyzed Aminocarbonylation/Carbonylative Cyclisation Sequence
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Sami Chniti, László Kollár, Attila Bényei, Ágnes Dörnyei, and Attila Takács
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Organic Chemistry ,Physical and Theoretical Chemistry - Published
- 2023
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12. Z ‐Selective Fluoroalkenylation of (Hetero)Aromatic Systems by Iodonium Reagents in Palladium‐Catalyzed Directed C−H Activation
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Attila Domján, Zoltán Novák, Zsombor Gonda, Gergő Sályi, Balázs L. Tóth, Orsolya Egyed, and Attila Bényei
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chemistry ,Reagent ,chemistry.chemical_element ,General Chemistry ,Combinatorial chemistry ,Palladium ,Catalysis - Published
- 2021
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13. The ortho effect in directed C–H activation†
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Attila Domján, Zoltán Novák, Orsolya Egyed, Balázs L. Tóth, Anna Monory, Bálint Szathury, András Stirling, and Attila Bényei
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Steric effects ,Reaction conditions ,Reaction rate ,Work (thermodynamics) ,Chemistry ,Computational chemistry ,Metalation ,Substrate (chemistry) ,Reactivity (chemistry) ,General Chemistry ,Dihedral angle - Abstract
The success of transition metal-catalysed ortho-directed C–H activation is often plagued by the effects of undesirable interactions between the directing group (DG) and other groups introduced into the aromatic core of the substrate. In particular, when these groups are in neighbouring positions, their interactions can affect profoundly the efficacy of the C–H activation by transition metals. In this work we introduce a simple substrate-only-based model to interpret the influence of steric hindrance of a group in ortho position to the DG in directed ortho-C–H bond activation reactions, and coined the term Ortho Effect (OE) for such situations. We consider simple descriptors such as torsion angle and torsional energy to predict and explain the reactivity of a given substrate in directed C–H activation reactions. More than 250 examples have been invoked for the model, and the nature of the ortho effect was demonstrated on a wide variety of structures. In order to guide organic chemists, we set structural and energetic criteria to evaluate a priori the efficiency of the metalation step which is usually the rate-determining event in C–H activations, i.e. we provide a simple and general protocol to estimate the reactivity of a potential substrate in C–H activation. For borderline cases these criteria help set the minimum reaction temperature to obtain reasonable reaction rates. As an example for the practical applicability of the model, we performed synthetic validations via palladium-catalysed 2,2,2-trifluoroethylation reactions in our lab. Furthermore, we give predictions for the necessary reaction conditions for several selected DGs., The term and concept of Ortho Effect (OE) is introduced for the description of steric effects in transition metal catalyzed directed ortho C–H activation reactions to explain and predict reactivities of substrates. more...
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- 2021
14. Catalytic Decomposition of Long-Chain Olefins to Propylene via Isomerization-Metathesis Using Latent Bicyclic (Alkyl)(Amino)Carbene-Ruthenium Olefin Metathesis Catalysts
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Márton Nagyházi, Ádám Lukács, Gábor Turczel, Jenő Hancsók, József Valyon, Attila Bényei, Sándor Kéki, and Róbert Tuba
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General Medicine ,General Chemistry ,Catalysis - Abstract
One of the most exciting scientific challenges today is the catalytic degradation of non-biodegradable polymers into value-added chemical feedstocks. The mild pyrolysis of polyolefins, including high-density polyethylene (HDPE), results in pyrolysis oils containing long-chain olefins as major products. In this paper, novel bicyclic (alkyl)(amino)carbene ruthenium (BICAAC-Ru) temperature-activated latent olefin metathesis catalysts, which can be used for catalytic decomposition of long-chain olefins to propylene are reported. These thermally stable catalysts show significantly higher selectivity to propylene at a reaction temperature of 75 °C compared to second generation Hoveyda-Grubbs or CAAC-Ru catalysts under ethenolysis conditions. The conversion of long-chain olefins (e.g., 1-octadecene or methyl oleate) to propylene via isomerization-metathesis is performed by using a (RuHCl)(CO)(PPh more...
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- 2022
15. Regio‐ and Stereoselective Synthesis of Benzoquinolizidines
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Anna Alekszi‐Kaszás, Klára Käfer‐Beke, Tamás R. Varga, Attila Bényei, Tibor Kovács, Attila Mándi, Tibor Kurtán, András Simon, and Péter Nemes
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General Chemistry - Published
- 2022
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16. Reactive Oxygen Species Production Is Responsible for Antineoplastic Activity of Osmium, Ruthenium, Iridium and Rhodium Half-Sandwich Type Complexes with Bidentate Glycosyl Heterocyclic Ligands in Various Cancer Cell Models
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Bokor, István Kacsir, Adrienn Sipos, Attila Bényei, Eszter Janka, Péter Buglyó, László Somsák, Péter Bai, and Éva
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osmium complex ,iridium complex ,ruthenium complex ,rhodium complex ,half-sandwich ,cooperative binding ,reactive oxygen species production ,glycosyl heterocycle ,oxadiazole ,triazole ,ovarian cancer ,Hodgkin’s lymphoma ,osteosarcoma - Abstract
Platinum complexes are used in chemotherapy, primarily as antineoplastic agents. In this study, we assessed the cytotoxic and cytostatic properties of a set of osmium(II), ruthenium(II), iridium(III) and rhodium(III) half-sandwich-type complexes with bidentate monosaccharide ligands. We identified 5 compounds with moderate to negligible acute cytotoxicity but with potent long-term cytostatic activity. These structure-activity relationship studies revealed that: (1) osmium(II) p-cymene complexes were active in all models, while rhodium(III) and iridium(III) Cp* complexes proved largely inactive; (2) the biological effect was influenced by the nature of the central azole ring of the ligands—1,2,3-triazole was the most effective, followed by 1,3,4-oxadiazole, while the isomeric 1,2,4-oxadiazole abolished the cytostatic activity; (3) we found a correlation between the hydrophobic character of the complexes and their cytostatic activity: compounds with O-benzoyl protective groups on the carbohydrate moiety were active, compared to O-deprotected ones. The best compound, an osmium(II) complex, had an IC50 value of 0.70 µM. Furthermore, the steepness of the inhibitory curve of the active complexes suggested cooperative binding; cooperative molecules were better inhibitors than non-cooperative ones. The cytostatic activity of the active complexes was abolished by a lipid-soluble antioxidant, vitamin E, suggesting that oxidative stress plays a major role in the biological activity of the complexes. The complexes were active on ovarian cancer, pancreatic adenocarcinoma, osteosarcoma and Hodgkin’s lymphoma cells, but were inactive on primary, non-transformed human fibroblasts, indicating their applicability as potential anticancer agents. more...
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- 2022
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17. Synthesis and Characterization of Novel PEPPSI type Pd–BICAAC Complexes
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Márton Nagyházi, Balázs Almási, Ádám Lukács, Attila Bényei, Tibor Nagy, Sándor Kéki, and Róbert Tuba
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A series of bicyclic alkylamino carbenes (BICAAC) (where N-aryl = dipp, mes, 2,6-dimethyl-4-(dimethylamino)phenyl, 5a-d) and their novel air- and moisture-resistant pyridine (pyridine, 4 dimethylaminopyridine) containing palladium PEPPSI-type Pd(II) complexes (6a-e) were synthetized and characterized. The new palladium complexes have shown high activity in Mizoroki–Heck coupling reaction even at as low as 100 ppm loading (TON up to 10000). Kinetic studies revealed that reactions carried out in the presence of elemental mercury resulted in decrease in activity. It indicates that the coupling reaction may have both molecular and Pd(0)-mediated catalytic paths. more...
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- 2022
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18. Synthesis of Hydrofluoroolefin‐based Iodonium Reagent via Dyotropic Rearrangement and Its Utilization in Fluoroalkylation
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János T. Csenki, Balázs L. Tóth, Ferenc Béke, Bálint Varga, Péter P. Fehér, András Stirling, Zsuzsanna Czégény, Attila Bényei, and Zoltán Novák
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General Medicine ,General Chemistry ,Catalysis - Abstract
[1,2]-shift of atoms in alkyl fragments belongs to the class of dyotropic rearrangements. Various atoms, including halogens can be involved in the migration, however participation of iodine is unprecedented. Herein, we report our experimental and DFT studies on the oxidation triggered dyotropic rearrangement of iodo and chloro functions via butterfly-type transition state to demonstrate the migrating ability of λ more...
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- 2022
19. Combined NMR, DFT and X-ray studies highlight structural and hydration changes of [Ln(AAZTA)]− complexes across the series
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Attila Bényei, Carlos Platas-Iglesias, David Esteban-Gómez, Daniela Delli Castelli, Mauro Botta, Zsolt Baranyai, and Lorenzo Tei
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Inorganic Chemistry ,Lanthanide ,Metal ,Steric effects ,Paramagnetism ,Dodecahedron ,Crystallography ,Structural change ,Chemistry ,visual_art ,visual_art.visual_art_medium ,Proton NMR ,Molecule - Abstract
We report a detailed structural study of [Ln(AAZTA)]− complexes by using a combination of experimental and theoretical tools. The analysis of the 1H NMR paramagnetic shift of the methyl peak across the series suggests that a structural change occurs between Ho and Er. Chemical exchange saturation transfer experiments were subsequently used to determine the number of coordinated water molecules and their corresponding exchange rates kex at 278 K. The Z-spectra recorded for the Ho(III) complex present two signals that confirm the presence of two coordinated water molecules, which are endowed with rather different exchange rates: 5.8(±3.0) × 103 and 8.1(±0.5) × 104 s−1. On the contrary, the Er(III) and Tm(III) complexes present a single signal in the Z-spectra. The exchange rate of the coordinated water molecule(s) decreases markedly across the series from Gd(III) to Yb(III). DFT calculations support the change in hydration number by the end of the lanthanide series, which is the result of an increased steric compression around one of the coordinated water molecules on decreasing the size of the metal ion. X-ray diffraction studies on the Er(III) complex confirm the presence of a single inner-sphere water molecule and the dodecahedral coordination environment of the metal ion. more...
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- 2020
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20. Reactions of 1-C-acceptor-substituted glycals with nucleophiles under acid promoted (Ferrier-rearrangement) conditions
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Levente Homolya, Dávid Antal, Máté Nagy, Éva Juhász-Tóth, Marietta Tóth, Attila Bényei, László Somsák, and László Juhász
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History ,Polymers and Plastics ,Thioglycosides ,Alcohols ,Organic Chemistry ,Carbohydrates ,Stereoisomerism ,Sulfhydryl Compounds ,General Medicine ,Business and International Management ,Biochemistry ,Industrial and Manufacturing Engineering ,Analytical Chemistry - Abstract
The reactivity of O-peracetylated and O-perbenzoylated 1-COOMe, 1-CONH
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- 2022
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21. Testing the role of the backbone length using bidentate and tridentate ligands in manganese-catalyzed asymmetric hydrogenation
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Zsófia Császár, Regina Kovács, Máté Fonyó, József Simon, Attila Bényei, György Lendvay, József Bakos, and Gergely Farkas
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Process Chemistry and Technology ,Physical and Theoretical Chemistry ,Catalysis - Published
- 2022
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22. Synthesis and characterization of novel PEPPSI type bicyclic (alkyl)(amino)carbene (BICAAC)-Pd complexes
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Márton Nagyházi, Balázs Almási, Ádám Lukács, Attila Bényei, Tibor Nagy, Sándor Kéki, and Róbert Tuba
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Inorganic Chemistry ,Organic Chemistry ,Spectroscopy ,Analytical Chemistry - Published
- 2022
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23. Effect of the replacement of tripodal 4N donors by two 2N chelators on the redox and cytotoxic activity of maltolato and deferipronato containing Co(III) complexes
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Sándor Nagy, Emese Tóth, István Kacsir, Attila Makai, Attila Bényei, and Péter Buglyó
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Tris ,Antineoplastic Agents ,010402 general chemistry ,Ligands ,01 natural sciences ,Biochemistry ,Medicinal chemistry ,Redox ,Inorganic Chemistry ,HeLa ,chemistry.chemical_compound ,Drug Stability ,Coordination Complexes ,Octahedral molecular geometry ,Pyridine ,medicine ,Molecule ,Humans ,Chelating Agents ,Cisplatin ,biology ,Molecular Structure ,010405 organic chemistry ,Cobalt ,biology.organism_classification ,0104 chemical sciences ,chemistry ,Amine gas treating ,Drug Screening Assays, Antitumor ,medicine.drug ,HeLa Cells - Abstract
Fourteen novel CoIII ternary complexes with the general formula [Co(4 N)(2O)]X2 or [Co(2 N)2(2O)]X2 where 4 N = tris(2-aminoethyl)amine (tren) or tris(2-pyridylmethyl)amine (tpa); 2 N = 1,10-phenantroline (phen), 2,2′-bipyridine (bipy), 1,2-diaminoethane (en) or 2-(aminomethyl)pyridine (ampy) and 2O = 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhpH), 3-hydroxy-2-methyl-4-pyrone (maltH) or 2-ethyl-3-hydroxy-4H-pyran-4-one (etmaltH) were synthesized, characterized and their redox features explored. Molecular structure of some selected [Co(2 N)2(2O)](ClO4)2 (2 N = phen, bipy, en; 2O = dhp, malt) or [Co(4 N)(2O)](ClO4)2 (4 N = tpa; 2O = etmalt) type complexes were assessed by X-ray diffraction and showed the expected octahedral geometry. Replacement of the 4 N donor ligands by two 2 N donor ligands resulted in the decrease of the cathodic peak potential of the complexes indicating easier reduction and allowing therefore the tailoring of the redox properties of the complexes. Screening of selected compounds against a human derived cancer cell line, HeLa, showed that, unlike the [Co(4 N)(2O)]X2 derivatives, the complexes containing 2 N = bipy or phen ligands have better anticancer activity than cisplatin or carboplatin. more...
- Published
- 2020
24. Design and application of diimine-based copper(<scp>i</scp>) complexes in photoredox catalysis
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Réka Adamik, Tamás Földesi, Attila Demeter, Krisztina J. Szekeres, Attila Bényei, Gellért Sipos, Bálint Nagy, Győző G. Láng, Timothy J. Peelen, Zoltán Novák, and Balázs L. Tóth
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chemistry.chemical_classification ,010405 organic chemistry ,Organic Chemistry ,chemistry.chemical_element ,Photoredox catalysis ,Halide ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Copper ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,chemistry ,Physical and Theoretical Chemistry ,Diimine ,Alkyl - Abstract
Structurally different bis(imino)copper(i) complexes were prepared in a highly modular manner and utilized as copper-based photocatalysts in the ATRA reactions of styrenes and alkyl halides. The new photocatalysts showed good catalytic activity and ensured efficient chemical transformations. more...
- Published
- 2019
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25. Tuning the redox potentials of ternary cobalt(III) complexes containing various hydroxamates
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Imre Zs.-Nagy, Etelka Farkas, Éva Kováts, István Kacsir, Máté Kozsup, Attila Bényei, Sándor Nagy, and Péter Buglyó
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010405 organic chemistry ,Stereochemistry ,Ligand ,Substituent ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Medicinal chemistry ,Redox ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Deprotonation ,Természettudományok ,chemistry ,Oxidation state ,Materials Chemistry ,Nitro ,Moiety ,Physical and Theoretical Chemistry ,Kémiai tudományok ,Cobalt - Abstract
Sixteen cobalt(III) complexes incorporating one of the investigated 4N donor tripodal amines in the presence or absence of differently substituted hydroxamates have been synthesized and the effect of the nature of the N-donor, size of the chelates formed and the effect of the type of the substituent(s) at the hydroxamate moiety on the redox properties of the complexes have been studied. The crystal and molecular structures of the new complexes, [Co(uns-penp)(H 2 O)Cl]Cl 2 ·H 2 O ( 4 ), [Co(tren)(phebha)](ClO 4 ) 2 ( 11 ), [Co(tpa)(bha)](ClO 4 ) 2 ·C 2 H 5 OH·H 2 O ( 15 ) and [Co(tpa)(phebha)](ClO 4 ) 2 ( 16 ) have also been determined by single crystal X-ray diffraction method. Cyclic voltammetric (CV) results indicated the irreversible reduction of Co(III) in all the investigated complexes. Out of the four studied tripodal amines, abap was found to decrease the Co(III/II) reduction potential far below the region of bioreductants. Decreasing of two of the chains by one CH 2 in tren compared to abap resulted in less negative reduction potential of the corresponding complex. Further positive shift was observed by introducing two (uns-penp), and especially three (tpa) π-back-bonding pyridyl rings into the chains of tetramines. In agreement with literature results, the 3+ oxidation state of the central cobalt ion was found to be extremely stabilized in the ternary complexes containing the doubly deprotonated benzohydroximate, but the metal ion is significantly more reducible in the ternary complexes with mono-deprotonated benzohydroxamate/derivative ligands. Measurable effect was not found on the redox potential via introduction of chloro or nitro substituents in para position into the phenyl moiety of bha − (Cl-bha − and NO 2 -bha − ). Significant positive shift (ca. 200 mV) was obtained, however, when R N = H was replaced by a phenyl ring in phebha − therefore complexes with this latter ligand can be likely candidates for the in vitro releasing of hydroxamates with proven biological activity. more...
- Published
- 2018
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26. Steric effects enforce double stereoselective N-coordination in twelve-membered binuclear palladium(II)-complexes containing chiral bridging aminoalkyl-phosphine ligands
- Author
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Kristóf Stágel, József Bakos, Szabolcs Balogh, György Lendvay, Zsófia Császár, Attila Bényei, and Gergely Farkas
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Steric effects ,010405 organic chemistry ,Ligand ,Stereochemistry ,Organic Chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Stereocenter ,Inorganic Chemistry ,chemistry.chemical_compound ,Stereospecificity ,chemistry ,Materials Chemistry ,Stereoselectivity ,Physical and Theoretical Chemistry ,Two-dimensional nuclear magnetic resonance spectroscopy ,Phosphine ,Palladium - Abstract
The configuration of the ligand's N-substituent was found to determine the stoichiometry and strict stereoselectivity of N-coordination in twelve-membered palladium dimers 2a-b. The novel palladium(II)-complexes 2a-b have been synthesized in the reaction of [Pd(COD)Cl2] and optically pure (S,S)-pentane-2,4-diyl based aminoalkyl-phosphine ligands Ph2PCH(CH3)CH2CH(CH3)NHR 1a-b (R = (R)-α-phenylethyl 1a, R = (R)-α-(1-naphthyl)ethyl 1b) with stereogenic nitrogen atom, and studied by various 1D and 2D NMR techniques in solution and in the case of 2a by single-crystal X-ray diffraction. As an unprecedented case, ligands 1a-b were found to yield exclusively 12-membered cyclic dinuclear Pd(II)-complexes with stereospecific coordination of both of the donor nitrogen atoms. Formation of the 12-membered ring is shown to reduce the steric hindrance of the bulky substituents with respect to the six-membered ring. more...
- Published
- 2018
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27. Novel Pd(PN,S)-complexes: Highly active catalysts designed for asymmetric allylic etherification
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Szabolcs Balogh, Attila Bényei, Máté M. Major, József Bakos, Gergely Farkas, Mária Guóth, and József Simon
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chemistry.chemical_classification ,Allylic rearrangement ,Process Chemistry and Technology ,Ring (chemistry) ,Combinatorial chemistry ,Catalysis ,Coordination complex ,chemistry ,Stereoselectivity ,Chelation ,Physical and Theoretical Chemistry ,Selectivity ,Two-dimensional nuclear magnetic resonance spectroscopy - Abstract
Six novel thioether-aminophosphine type ligands with a general formula (Ar1)2PN(R1)CHR2(CH2)nCH(R3)SAr2 has been synthesized. The modular structure of the ligands and the new methodologies developed for their preparation enabled the systematic variation of their bridge length (n = 0 or 1), the substitution pattern of the backbone (R2, R3 = H or Me) as well as the P-, N- and S-substituents (Ar1 = Ph or 3,5-Me2C6H3, R1 = Et or iPr and Ar2 = Ph, 4-MeC6H4, or 4-MeOC6H4, respectively). The ligands proved to be effective in Pd-catalyzed asymmetric allylic etherification reactions providing the products in high yields (up to 95%) and with good enantioselectivities (up to 86%) using unprecedentedly low (0.2 mol%) loadings of the chiral Pd-catalyst. Based on these findings, a new scalable protocol has been developed for the preparation of chiral allylic ethers. Furthermore, the Pd(II) coordination chemistry of the ligands was thoroughly investigated by 1D and 2D NMR methods as well as by X-ray crystallography with special attention to the conformation of the chelate ring and the stereoselectivity of the sulfur coordination. Based on these studies, the main factors determining activity and selectivity of the catalytic system have been identified. more...
- Published
- 2021
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28. Efficient stereochemical communication in phosphine-amine palladium-complexes: Exploration of N-substituent effects in coordination chemistry and catalysis
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Szabolcs Balogh, Evelin Nemes, Gergely Farkas, József Bakos, Zsófia Császár, György Lendvay, Attila Bényei, Kristóf Stágel, and Imre Tóth
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Steric effects ,chemistry.chemical_classification ,Coordination sphere ,010405 organic chemistry ,Stereochemistry ,Organic Chemistry ,Substituent ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Coordination complex ,Inorganic Chemistry ,chemistry.chemical_compound ,Tsuji–Trost reaction ,chemistry ,Materials Chemistry ,Moiety ,Physical and Theoretical Chemistry ,Phosphine ,Palladium - Abstract
Six-membered chelate complexes of type [Pd(1a-e)Cl2] (2a-e) and [Pd(1a-e)(η3-PhCHCHCHPh)]BF4 (3a-e) of a series of systematically varied chiral phosphine-amine ligands (S,S)-Ph2PCH(CH3)CH2CH(CH3)NHR 1a-e (R = benzyl 1a, R = ethyl 1b, R = (S)-α-phenylethyl 1c, R = isopropyl 1d, R = methyl 1e) have been studied. The complexes 2a-e were characterized by X-ray crystallography, DFT analysis and in solution by 1D and 2D NMR spectroscopy. A very good correlation has been observed between the steric demand of the N-substituent and the distortion of the chelate. Furthermore, it has been proved that sterically more demanding N-substituents are capable of distorting the chelate to a larger extent along one single, well defined conformational pathway. The careful variation of the N-substituent thus allows a precise stereochemical fine tuning of the metal's coordination sphere. As a substantiation of this concept, the investigation of complexes 3a-e revealed that the exo/endo ratio as well as the twisting of the allyl moiety around the Pd-allyl axis can easily be modified by the proper choice of the nitrogen substituent. Furthermore, Pd-catalysts with ligands 1a-e provided high enantioselectivities (up to 96%) in asymmetric allylic alkylation reactions. more...
- Published
- 2017
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29. Stereoselective Thioconjugation by Photoinduced Thiol-ene Coupling Reactions of Hexo- and Pentopyranosyl d- and l-Glycals at Low-Temperature-Reactivity and Stereoselectivity Study
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Viktor, Kelemen, Miklós, Bege, Dániel, Eszenyi, Nóra, Debreczeni, Attila, Bényei, Tobias, Stürzer, Pál, Herczegh, and Anikó, Borbás
- Subjects
Carbohydrate Chemistry | Hot Paper ,thiyl radical addition ,Full Paper ,photoactivation ,glycal ,Full Papers ,stereoselective synthesis ,thioglycoside - Abstract
A comprehensive optimization and mechanistic study on the photoinduced hydrothiolation of different d‐ and l‐ hexo‐ and pentoglycals with various thiols was performed, at the temperature range of RT to −120 °C. Addition of thiols onto 2‐substituted hexoglycals proceeded with complete 1,2‐cis‐α‐stereoselectivity in all cases. Hydrothiolation of 2‐substituted pentoglycals resulted in mixtures of 1,2‐cis‐α‐ and ‐β‐thioglycosides of varying ratio depending on the configuration of the reactants. Hydrothiolation of unsubstituted glycals at −80 °C proceeded with excellent yields and, except for galactal, provided the axially C2‐S‐linked isomers with high selectivity. Cooling was always beneficial to the efficacy, increased the yields and in most cases significantly raised the stereoselectivity. The suggested mechanism explains the different conformational preferences of the intermediate carbon‐centered radicals, which is a crucial factor in the stereoselectivity of the reactions., Three types of acetylated glycals were reacted with various thiols under UV‐irradiation at the temperature range of RT to −120 °C. Cooling proved always beneficial to the reaction efficacy, being −80 °C the optimal temperature in most cases. The low‐temperature thiol‐ene coupling of glycals was found to provide an easy access to 1,2‐cis‐α‐1‐thio‐hexosides up to tetrasaccharides, 1,2‐cis‐α‐ and β‐1‐thio‐pentosides and axially C2‐S‐linked glycomimetics. more...
- Published
- 2019
30. Characterization of the ionic liquid obtained by chlorosulfonation of 1-methylimidazole: 1-methyl-3-sulfonic acid imidazolium chloride, 1-methylimidazolium chlorosulfate or a zwitterionic salt?
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Máté Papp, Csaba Fehér, Rita Skoda-Földes, Béla Urbán, Attila Bényei, and Gábor Szalontai
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chemistry.chemical_classification ,Salt (chemistry) ,02 engineering and technology ,Nuclear magnetic resonance spectroscopy ,Sulfonic acid ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Catalysis ,chemistry.chemical_compound ,Hydrolysis ,chemistry ,Organic reaction ,Ionic liquid ,Polymer chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,0210 nano-technology ,1-Methylimidazole ,Spectroscopy - Abstract
A great number of organic reactions catalyzed by the ionic liquid product of chlorosulfonation of 1-methylimidazole have been reported recently. At the same time controversial assumptions have appeared on the real structure of the catalyst. In the present report the primarily formed chlorosulfonation product is proved to be 1-methylimidazolium chlorosulfate ([HMim]+[SO3Cl]−) instead of 1-methyl-3-sulfonic acid imidazolium chloride, reported previously. The former structure is confirmed by X-ray crystallography and NMR spectroscopy, including 1H-, 13C-, 17O- and 15N–1H HSQC measurements. 1H and 17O NMR experiments support fast hydrolysis of [HMim] [SO3Cl] resulting in the formation of [HMim][HSO4] in the presence of traces of water. more...
- Published
- 2021
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31. Control of structure, stability and catechol oxidase activity of copper(<scp>ii</scp>) complexes by the denticity of tripodal platforms
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Tamás Gajda, Nóra V. May, Ferenc Matyuska, and Attila Bényei
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Denticity ,biology ,010405 organic chemistry ,Stereochemistry ,Potentiometric titration ,chemistry.chemical_element ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Copper ,Catalysis ,Square pyramidal molecular geometry ,0104 chemical sciences ,Trigonal bipyramidal molecular geometry ,Deprotonation ,chemistry ,Tripodal ligand ,Polymer chemistry ,Materials Chemistry ,biology.protein ,Catechol oxidase - Abstract
Copper(II) complexes of a new polydentate tripodal ligand trenpyz (L, tris[2-(5-pyrazolylmethyl)aminoethyl]amine) were characterized in both solution and solid states. A combined evaluation of potentiometric UV-Vis and EPR data provided both thermodynamic and structural information on the complexes formed in solution. In equimolar solution the highly stable square pyramidal CuHL and trigonal bipyramidal CuL are the dominant species at around pH 3 and 5–8, respectively. Above pH 8 further deprotonation was observed (pK = 9.56), which is related to the formation of a copper(II)-bound pyrazolate anion. This creates the possibility for the formation of oligonuclear complexes, through pyrazolate bridges, and at a 3/2 Cu(II)/L ratio three trinuclear complexes were identified, similar to the copper(II)–tachpyz (N,N′,N′′-tris(5-pyrazolylmethyl)-1,3,5-cis,cis-triamino-cyclohexane) system studied earlier. The trinuclear complexes of the two ligands have considerably different speciations, due to the different denticities of tripodal platforms. At the optimal pH the catechol oxidase activities of the triply deprotonated trinuclear complexes of trenpyz and tachpyz are similar, but the pH-rate constant profiles are significantly different, as a consequence of the deviations in their speciation. Consequently, the H2dtbc oxidation promoted by these trinuclear complexes can be easily controlled by the denticity of the tripodal ligands, since it affects the coordination environment of the central metal ion, which is proposed to be the main actor during the reaction. more...
- Published
- 2017
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32. Synthesis ofC-2- andC-3-SulfonatomethylO- andS-Glycosides by Horner-Wadsworth-Emmons Olefination
- Author
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István Komáromi, Attila Mándi, Dániel Eszenyi, Mihály Herczeg, Attila Bényei, and Anikó Borbás
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chemistry.chemical_classification ,010405 organic chemistry ,Stereochemistry ,Organic Chemistry ,Glycoside ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Molecular dynamics ,chemistry ,Glucoside ,Nucleophilic substitution ,Moiety ,Physical and Theoretical Chemistry - Abstract
The applicability of the Horner–Wadsworth–Emmons olefination to the introduction of the sulfonatomethyl moiety at the 2- and 3-positions of orthogonally protected O- and S-glycosides has been studied. The conformational preferences and relative energies of the exo- and endocyclic alkenesulfonic acids obtained were analysed by high-temperature molecular dynamics and DFT calculations. Thioglycosides bearing a sulfonatomethyl moiety at the secondary position have been prepared for the first time. Finally, the attempted synthesis of 2-sulfonatomethyl glucoside by nucleophilic substitution reaction is also described. more...
- Published
- 2016
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33. Synthesis, Structural Analysis and Application of Aryl‐Diadamantyl Phosphine ligands in Palladium Catalyzed Cross‐Coupling Reactions
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András Kotschy, Fruzsina Szabó, Dániel Csaba Simkó, Tamás Gáti, Ádám Sinai, Attila Paczal, Attila Bényei, and Zoltán Novák
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Tosylhydrazone ,chemistry.chemical_compound ,chemistry ,Aryl ,Organic Chemistry ,chemistry.chemical_element ,Physical and Theoretical Chemistry ,Combinatorial chemistry ,Amination ,Coupling reaction ,Phosphine ,Catalysis ,Palladium - Published
- 2020
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34. Backbone effects in the synthesis, coordination chemistry and catalytic properties of new chiral heterobidentate ligands with P,N and S,N donor sets
- Author
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Gergely Farkas, József Bakos, Máté M. Major, Zsófia Császár, Szabolcs Balogh, and Attila Bényei
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chemistry.chemical_classification ,010405 organic chemistry ,Stereochemistry ,Organic Chemistry ,Enantioselective synthesis ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Coordination complex ,Catalysis ,Inorganic Chemistry ,Tsuji–Trost reaction ,chemistry ,Materials Chemistry ,Stereoselectivity ,Physical and Theoretical Chemistry ,Spectroscopy ,Two-dimensional nuclear magnetic resonance spectroscopy ,Palladium - Abstract
Novel alkane-diyl based heterobidentate P,N and S,N ligands with the general formula R1R2NCH(R3)(CH2)nCH(R4)Q (R1 = Me or iPr; R2 = H or Me; R3, R4 = H or Me; n = 0, 2; Q = PPh2 or SPh) have been prepared starting from cyclic sulfate esters or naturally occurring compounds with C1 symmetry. The length of the ligands’ backbone and the reaction conditions applied strongly affected the stereochemical outcome of the synthesis when using cyclic sulfates as starting materials. Palladium(II)-complexes of the new ligands were characterized by 1D and 2D NMR spectroscopy in solution and in several cases by X-ray crystallography in the solid phase. The structural versatility of the ligands enabled the straightforward comparison of the stereoselectivity of their coordination as a function of their tether length, backbone substitution pattern, donor sets and relative carbon atom configuration in their backbone. The catalytic features of the novel compounds were investigated in asymmetric allylic alkylation reactions where the tether length proved to be a crucial factor in determining enantioselectivity. more...
- Published
- 2020
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35. Synthesis of Multifunctional Aryl(trifloxyalkenyl)iodonium Triflate Salts
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Attila Bényei, Balázs L. Tóth, András Stirling, Orsolya Egyed, Ferenc Béke, and Zoltán Novák
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lcsh:Chemistry ,chemistry.chemical_compound ,lcsh:QD1-999 ,chemistry ,Trimethylsilyl trifluoromethanesulfonate ,General Chemical Engineering ,Aryl ,General Chemistry ,Benzene ,Medicinal chemistry ,Trifluoromethanesulfonate ,Article - Abstract
A convenient procedure for the synthesis of aryl(trifloxyalkenyl)iodonium triflate salts from commercially available (diacetoxyiodo)benzene, trimethylsilyl trifluoromethanesulfonate, and acetylenes under mild conditions was developed. The obtained multifunctional hypervalent vinyliodonium salts equipped with electrophilic and nucleophilic functions could serve as novel C2 synthons for organic transformations. The structure of the iodonium salts was identified by multidimensional NMR spectroscopy and X-ray crystallography. more...
- Published
- 2019
36. Bivalent glycoconjugates based on 1,5-diazabicyclo[3.3.0]octa-3,6-diene-2,8-dione ('bimane') as a central scaffold
- Author
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Attila Bényei, László Szilágyi, and Tamás Szabó
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chemistry.chemical_classification ,Glycosylation ,Diene ,010405 organic chemistry ,Chemistry ,Stereochemistry ,Glycoconjugate ,Organic Chemistry ,Disaccharide ,Thio ,General Medicine ,010402 general chemistry ,Bridged Bicyclo Compounds, Heterocyclic ,01 natural sciences ,Biochemistry ,Fluorescence ,Cycloaddition ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Bimane ,Természettudományok ,Glycosyl ,Kémiai tudományok ,Glycoconjugates - Abstract
The heteroaromatic fused diazabicyclic "bimane" ring system, discovered four decades ago, is endowed with remarkable chemical and photophysical properties. No carbohydrate derivatives of bimanes have, however, been described thus far. Here we report on the syntheses of a range of bimanes decorated with various glycosyl residues. Mono- and disaccharide residues were attached to syn- or anti-bimane central cores via thio-, disulfido- or selenoglycosidic linkages to obtain novel fluorescent or nonfluorescent glycoconjugates. Cu(I)-catalyzed cycloaddition of glycosyl azides to a bimane diethynyl derivative furnished further bivalent glycoconjugates with sugar residues linked to the central bimane core via 1,2,3-triazole rings. We have determined the crystal and molecular structures of several glycosylated and non-glycosylated bimanes and report fluorescence data for the new compounds. more...
- Published
- 2018
37. Development and Characterisation of Modified Release Hard Gelatin Capsules, Based on In Situ Lipid Matrix Formation
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Géza Regdon, Ferenc Fenyvesi, Zoltán Ujhelyi, Dávid Sinka, Pálma Fehér, Bence Csontos, Gábor Vasvári, Tamás Sovány, Ildikó Bácskay, Judit Váradi, Attila Bényei, Miklós Vecsernyés, and Thi Le Phuong Nguyen more...
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Drug Liberation ,Diclofenac ,Cetostearyl alcohol ,Drug Compounding ,Pharmaceutical Science ,Capsules ,02 engineering and technology ,Aquatic Science ,030226 pharmacology & pharmacy ,Fats ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Drug Discovery ,Technology, Pharmaceutical ,Thermal analysis ,Dissolution ,Softening ,Ecology, Evolution, Behavior and Systematics ,Active ingredient ,Chromatography ,Ecology ,Chemistry ,Capsule ,General Medicine ,Diclofenac Sodium ,021001 nanoscience & nanotechnology ,Lipids ,Solubility ,Gelatin ,0210 nano-technology ,Agronomy and Crop Science ,Oils - Abstract
A new technology was developed to form extended release hard gelatin capsules, based on the lipid matrix formation of Gelucire 50/13 and cetostearyl alcohol. Matrices were formed in situ by filling pulverised lipids, ethylcellulose and active ingredients such as diclofenac sodium, acetaminophen and metronidazol into capsules and heating at 63°C for 11 min. Effects of heating were investigated also on the brittleness of capsule shells. Inhibition of the evaporation of water reduced capsule damage. Dissolution tests and texture analysis were performed to discover the release and mechanical profiles of the matrices. Tests were repeated after 1 month storage and results were compared. Gelucire 50/13 alone prolonged drug release but cetostearyl alcohol slowed drug liberation even further. Drug release from all compositions was found to follow first-order kinetic. Significant softening of the matrices was detected during storage in composition containing only Gelucire 50/13, ethylcellulose and diclofenac sodium. Thermal analysis and IR tests were also performed to discover physicochemical interactions between active pharmaceutical ingredients and excipients. Thermal analysis confirmed a notable interaction between diclofenac sodium and Gelucire 50/13 which could be the cause of the observed softening. In conclusion, modified release hard gelatin capsules were developed by a simple and fast monolithic lipid matrix formation method. more...
- Published
- 2018
38. A novel 1,3,5-triaminocyclohexane-based tripodal ligand forms a unique tetra(pyrazolate)-bridged tricopper(<scp>ii</scp>) core: solution equilibrium, structure and catecholase activity
- Author
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Robert K. Szilagyi, Attila Szorcsik, Nóra Veronika Nagy, Ferenc Matyuska, Attila Bényei, and Tamás Gajda
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Bridged-Ring Compounds ,Denticity ,Coordination sphere ,Stereochemistry ,Catechols ,chemistry.chemical_element ,Crystal structure ,Pyrazole ,Ligands ,010402 general chemistry ,01 natural sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Természettudományok ,Biomimetic Materials ,Coordination Complexes ,Kémiai tudományok ,Cyclohexylamines ,010405 organic chemistry ,Hydrogen-Ion Concentration ,Copper ,Square pyramidal molecular geometry ,0104 chemical sciences ,Crystallography ,chemistry ,Tripodal ligand ,Pyrazoles ,Density functional theory ,Oxidation-Reduction ,Catechol Oxidase - Abstract
Copper(II) complexes of a polydentate tripodal ligand L × 3HCl (L = N,N′,N′′-tris(5-pyrazolylmethyl)-cis,cis-1,3,5-triaminocyclohexane) were characterized in both solution and solid states. Combined evaluation of potentiometric, UV-VIS, and EPR data indicated the formation of two mononuclear (CuHL, CuL) and three trinuclear (Cu3H−xL2, x = 2, 3, 4) complexes. The high stability and spectroscopic properties of the CuL species indicate a coordination of two pyrazole rings in addition to the three secondary amino groups of L in a square pyramidal geometry. In parallel with the formation of trinuclear species, intense charge transfer bands appear at around 400–500 nm, which indicate the formation of pyrazolate-bridged complexes. The crystal structure of [Cu3H−4L2](ClO4)2·5H2O (1) reveals the formation of a unique trinuclear complex that features a tetra(pyrazolate)-bridged linear tricopper(II) core. The Cu⋯Cu interatomic distances are around 3.8 A. The two peripheral copper(II) ions have a slightly distorted square pyramidal geometry. The four pyrazole rings bound to the peripheral copper(II) ions are deprotonated and create a flattened tetrahedral environment for the central copper(II), i.e. the formation of the trinuclear complexes is under the allosteric control of the two peripheral copper(II) ions. The triply deprotonated trinuclear complex is an efficient catechol oxidase mimic with a surprisingly low pH optimum at pH = 5.6. Since the mononuclear CuL species is not able to promote the oxidation of 3,5-di-tert-butylcatechol, we assume that the central copper(II) ion of the trinuclear complex with an unsaturated coordination sphere has a fundamental role in the binding and oxidation of the substrate. The experimental and structural details were further elaborated by a series of hybrid density functional theory calculations that support the presence of an antiferromagnetically coupled ground state. However, the magnitude and the pattern of spin coupling are dependent on the composition of the functionals. The optimized theoretical structures highlight the role of the crystal packing effects in inducing asymmetry between the two peripheral copper(II) sites. more...
- Published
- 2016
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39. Application of zwitterionic phosphapalladacycles in aqueous phase Suzuki-Miyaura coupling
- Author
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Gergely Farkas, Attila Bényei, László Szi-Ferenc, József Bakos, and Zsófia Császár
- Subjects
Aqueous solution ,010405 organic chemistry ,Chemistry ,Ligand ,Organic Chemistry ,Aqueous two-phase system ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Combinatorial chemistry ,0104 chemical sciences ,Catalysis ,Inorganic Chemistry ,Coupling (electronics) ,Metal ,Negative charge ,visual_art ,visual_art.visual_art_medium - Abstract
The catalytic application of novel six-membered zwitterionic palladacycles with formal negative charge on the metal center and positive charge on the ancillary ligand is reported in the aqueous phase Suzuki-Miyaura coupling. The novel catalysts provide excellent activities with high functional group tolerance in the carbon-carbon bond forming reaction yielding substituted biaryls in high yields. more...
- Published
- 2018
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40. Stereoselective coordination: a six-membered P,N-chelate tailored for asymmetric allylic alkylation
- Author
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Zs. Császár, József Bakos, Imre Tóth, György Lendvay, Attila Bényei, and Gergely Farkas
- Subjects
Inorganic Chemistry ,chemistry.chemical_classification ,Tsuji–Trost reaction ,Stereospecificity ,chemistry ,Stereochemistry ,Stereoselectivity ,Ring (chemistry) ,Medicinal chemistry ,Two-dimensional nuclear magnetic resonance spectroscopy ,Isopropyl ,Alkyl ,Catalysis - Abstract
Six-membered chelate complexes [Pd(1a-b)Cl2], (2a-b) and [Pd(1a-b)(η(3)-PhCHCHCHPh)]BF4, (3a-b) of P,N-type ligands 1a, ((2S,4S)-2-diphenyl-phosphino-4-isopropylamino-pentane) and 1b, ((2S,4S)-2-diphenyl-phosphino-4-methylamino-pentane) have been prepared. The Pd-complexes have been characterized in solution by 1D and 2D NMR spectroscopy. The observed structures were confirmed by DFT calculations and in the case of 2a also by X-ray crystallography. Unexpectedly, the coordination of the all-carbon-backbone aminophosphine 1a resulted in not only a stereospecific locking of the donor nitrogen atom into one of the two possible configurations but also the conformation of the six-membered chelate rings containing three alkyl substituents was forced into the same single chair structure showing the axially placed isopropyl group on the coordinated N-atom. The stereodiscriminative complexation of 1a led to the formation of a palladium catalyst with a conformationally rigid chelate having a configurationally fixed nitrogen and electronically different coordination sites due to the presence of P and N donors. The stereochemically fixed catalyst provided excellent ee's (up to 96%) and activities in asymmetric allylic alkylation reactions. In contrast, the chelate rings formed by 1b exist in two different chair conformations, both containing axial methyl groups, but with the opposite configurations of the coordinated N-atom. Pd-complexes of 1b provided low enantioselectivities in similar alkylations, therefore emphasizing the importance of the stereoselective coordination of N-atoms in analogous P-N chelates. The factors determining the coordination of the ligands were also studied with respect to the chelate ring conformation and the nitrogen configuration. more...
- Published
- 2015
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41. Half-sandwich complexes of ruthenium, osmium, rhodium and iridium with <scp>dl</scp>-methionine or S-methyl-<scp>l</scp>-cysteine: a solid state and solution equilibrium study
- Author
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Jana Kasparkova, Tereza Radosova Muchova, János Patalenszki, Attila Bényei, Linda Bíró, and Péter Buglyó
- Subjects
Aqueous solution ,Chemistry ,Stereochemistry ,General Chemical Engineering ,Diastereomer ,chemistry.chemical_element ,General Chemistry ,Medicinal chemistry ,Rhodium ,Ruthenium ,Stereocenter ,Metal ,chemistry.chemical_compound ,Thioether ,visual_art ,visual_art.visual_art_medium ,Osmium - Abstract
[(η6-p-cym)Ru(H2O)3]2+ binding strength of the thioether ligands DL-methionine (H2met+) or S-methyl-L-cysteine (H2mecys+) was studied with the combined use of pH-potentiometry, NMR and mass spectrometry in aqueous solution. Both ligands were found to form stable [(η6-p-cym)RuA]+ complexes with [S, NH2, COO−] coordination of the amino acids over a wide pH-range. A log βRuA value of 17.2(2) was obtained from NMR titrations for the met system by a competition reaction with hydroxide ions. Comparison of the [(η6-p-cym)Ru(H2O)3]2+ binding strength of the [O, O, O] (citrate), [O, N, O] (isoserine) and [S, N, O] (met) donor sets at pH = 7.4 reveals the exclusive formation of a [S, N, O] chelated metal complex. Synthesis and characterisation of [(η6-p-cym)Ru(L)]X, [(η6-p-cym)Os(L)]Cl or [(η5-Cp*)M′(L)]Cl (L = mecys, DL-met, L-met; X = Cl, NO3, CF3SO3; M′ = Rh, Ir) complexes together with the molecular structures of the [(η6-p-cym)Ru(mecys)]NO3 (10) and [(η6-p-cym)Ru(met)]NO3 (11) obtained by the X-ray diffraction method are reported. Both tridentate ligands form chiral-at-metal complexes in which the configuration of the metal centre is determined by the ligands containing a stereogenic centre (αC) as well. Diffraction data indicate that 10 contains the RRuRαCSS stereoisomer while 11 consists of the RRuSαCRS and SRuRαCSS enantiomers in the lattice. Owing to the labile configuration of the thioether sulfurs epimerisation in both systems was detected and the ratio of the diastereomers was estimated. 11 together with [(η6-p-cym)Ru(L-met)]Cl (3), [(η5-Cp*)Rh(DL-met)]Cl (7) and [(η5-Cp*)Ir(DL-met)]Cl (9) were tested for their in vitro cytotoxicity using human-derived ovarian cancer lines (A2780) and showed no anti-proliferative activity in the concentration range (0–50 μM) studied. more...
- Published
- 2015
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42. Tricyclanos: conformationally constrained nucleoside analogues with a new heterotricycle obtained from a d-ribofuranose unit
- Author
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Gyula Batta, Szabolcs Varga, Attila Bényei, Anikó Borbás, Máté Kicsák, Pál Herczegh, Attila Mándi, and Mihály Herczeg
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Silylation ,010405 organic chemistry ,Stereochemistry ,Gyógyszerészeti tudományok ,Organic Chemistry ,Enantioselective synthesis ,Absolute configuration ,Cytidine ,Orvostudományok ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Stereocenter ,chemistry.chemical_compound ,chemistry ,Reagent ,Hydroxymethyl ,Physical and Theoretical Chemistry ,Nucleoside - Abstract
A novel type of nucleoside analogue in which the sugar part is replaced by a new tricycle, 3,7,10-trioxa-11-azatricyclo[5.3.1.05,11]undecane has been prepared by substrate-controlled asymmetric synthesis. 1,5-Dialdehydes obtained from properly protected or unprotected uridine, ribothymidine, cytidine, inosine, adenosine and guanosine by metaperiodate oxidation reacted readily with tris(hydroxymethyl)aminomethane to provide the corresponding tricyclic derivatives with three new stereogenic centers. Through a double cyclisation cascade process the tricyclic compounds were obtained in good to high yields, with very high diastereoselectivity. Formation of one stereoisomer, out of the eight possible, was observed in all cases. The absolute configuration of the new stereotriad-containing tricyclic systems was aided by conventional NMR experiments followed by chemical shift calculations using an X-ray crystal structure as reference that was in good agreement with H–H distances obtained from a new ROESY NMR method. The synthesis was compatible with silyl, trityl and dimethoxytrityl protecting groups. A new reagent mixture containing ZnCl2, Et3SiH and hexafluoroisopropanol was developed for detritylation of the acid-sensitive tricyclano nucleosides. more...
- Published
- 2017
43. Tailoring the local environment around metal ions: a solution chemical and structural study of some multidentate tripodal ligands
- Author
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Tamás Gajda, Éva Kováts, Ferenc Matyuska, Ágnes Dancs, Nóra V. May, Attila Bényei, and Attila Szorcsik
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Denticity ,010405 organic chemistry ,Ligand ,Metal ions in aqueous solution ,Inorganic chemistry ,chemistry.chemical_element ,Zinc ,010402 general chemistry ,01 natural sciences ,Copper ,Square pyramidal molecular geometry ,0104 chemical sciences ,Inorganic Chemistry ,Trigonal bipyramidal molecular geometry ,Crystallography ,chemistry ,Chelation - Abstract
Manganese(II), copper(II) and zinc(II) complexes of four polydentate tripodal ligands (tachpyr (N,N′,N′′-tris(2-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane), trenpyr (tris[2-(2-pyridylmethyl)aminoethyl]amine, tach3pyr (N,N′,N′′-tris(3-pyridylmethyl)-cis,cis-1,3,5-triaminocyclohexane) and tren3pyr (tris[2-(2-pyridylmethyl)aminoethyl]amine)) were characterized in both solution and solid states. A combined evaluation of potentiometric, UV-VIS, NMR and EPR data allowed the conclusion of both thermodynamic and structural information about the complexes formed in solution. The four tailored polydentate tripodal ligands studied here exhibit a high thermodynamic stability, and a variety of coordination environments/geometries for the studied transition metal ions. Our data indicate that tachpyr is a more efficient zinc(II) chelator and a similar copper(II) chelator compared to trenpyr. Considering the higher number of N-donors and conformational flexibility of trenpyr, as well as the energy demanding switch to the triaxial conformation required for metal ion binding of tachpyr, the above observation is surprising and is very likely due to the encapsulating effect of the more rigid tachpyr skeleton. This relative binding preference of tachpyr for zinc(II) may be related to the observation that zinc(II) is one of the principal metals targeted by tachpyr in cells. In contrast, trenpyr is a considerably more efficient manganese(II) chelator, since it acts as a heptadentate ligand in the aqueous Mn(trenpyr) complex. The crystal structures of copper(II) and zinc(II) complexes of tachpyr indicated important differences in the ligand conformation, induced by the position of counter ions, as compared to earlier reports. The closely related new ligands, tach3pyr and tren3pyr, have been designed to form oligonuclear complexes. Indeed, we obtained a three dimensional polymer with a copper(II)/tren3pyr ratio of 11/6. Within this metal–organic framework, three distinctly different copper geometries can be identified: square pyramidal, trigonal bipyramidal and tetrahedral. Two square pyramidal and four trigonal bipyramidal copper centres create a hexanuclear subunit with a large inside cavity. These moieties are linked by tetrahedral copper(II) centres, constructing the three-dimensional polymer structure. The formation of such polynuclear complexes was not detected in solution. Both tach3pyr and tren3pyr form only mononuclear complexes with square pyramidal and trigonal bipyramidal geometries, respectively. more...
- Published
- 2017
44. Vanadate complexes of 3-hydroxy-1,2-dimethyl-pyridinone: Speciation, structure and redox properties
- Author
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Karoly Kozma, Attila Bényei, Éva A. Enyedy, Zsófia Paár, Tamás Jakusch, and Tamás Kiss
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Ligand ,Trans effect ,Inorganic chemistry ,Vanadium ,chemistry.chemical_element ,Protonation ,Nuclear magnetic resonance spectroscopy ,Ascorbic acid ,Medicinal chemistry ,Redox ,Inorganic Chemistry ,NMR spectra database ,Természettudományok ,chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Kémiai tudományok - Abstract
Several articles were published about the vanadate–3-hydroxy-1,2-dimethyl-pyridinone (Hdhp) system, however, the results are contradictory and not complete: pH-potentiometry and 51V NMR spectroscopy were used to clarify this complicated system. The eleven peaks in the spectra at different chemical shifts were assigned to ten stoichiometrically different compounds; four of them are new, never identified or assigned before. Besides the simple mono (in two different protonation states) and bis complexes (in three different protonation states) a tris complex, three dinuclear and a trinuclear complex were found based on the 51V NMR spectra measured at different pH values and various metal ion concentrations and metal-to-ligand ratios. As a joint evaluation of the two methods, overall stability constants were calculated for all species. X-ray structure of the potassium salt of the bis complex, [V(V)O2(dhp)2]− was also determined. The trans effect of the oxido-oxygens results in maltolato-type coordination of the ligand instead of the catecholate-like chelation. The redox properties of [V(V)O2(dhp)2]− and some other prodrug vanadium(V) bis complexes were investigated by spectrophotometry in aqueous solution via their reduction by glutathione (GSH) and l -ascorbic acid (ASC) under strictly anaerobic conditions and by cyclic voltammetry at physiological pH. The reduction was found to be much faster by ASC in all cases as compared with GSH and the reaction rate of the reduction of [V(V)O2(dhp)2]− was prominently high most probably due to the formation of the significantly higher stability of the corresponding vanadium(IV) complex. more...
- Published
- 2014
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45. α-Azido Ketones, Part 8: Base-Induced Coupling of α-Azido Ketones with a 1,2-Diaza-1,3-diene as a Michael Acceptor
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Éva Juhász-Tóth, Gianfranco Favi, Tamás Patonay, Orazio A. Attanasi, and Attila Bényei
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chemistry.chemical_classification ,Diene ,Base (chemistry) ,Stereochemistry ,Organic Chemistry ,Diastereomer ,Adduct ,chemistry.chemical_compound ,Természettudományok ,chemistry ,Michael reaction ,Hydrazoic acid ,Kémiai tudományok ,Carbanion - Abstract
Carbanions generated from various acyclic and cyclic α-azido ketones in the presence of bases were reacted with ethyl 3-[(carbamoylimino)amino]but-2-enoate as a Michael acceptor to give the corresponding adducts. The adducts of acyclic azides were unstable and eliminated hydrazoic acid to give the corresponding ethyl 2-[1-[(carbamoylamino)imino]ethyl]-4-oxo-4-phenylbut-2-enoates as (E,E/Z,E)-diastereomeric mixtures. The relative configuration of these diastereomers was determined by X-ray analysis. Adducts of cyclic α-azido ketones were obtained in diastereomerically pure form, with the exception of 2-azidobenzosuberone. more...
- Published
- 2014
- Full Text
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46. Cover Feature: Stereoselective Thioconjugation by Photoinduced Thiol‐ene Coupling Reactions of Hexo‐ and Pentopyranosyl <scp>d</scp> ‐ and <scp>l</scp> ‐Glycals at Low‐Temperature—Reactivity and Stereoselectivity Study (Chem. Eur. J. 64/2019)
- Author
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Dániel Eszenyi, Attila Bényei, Anikó Borbás, Pál Herczegh, Miklós Bege, Tobias Stürzer, Nóra Debreczeni, and Viktor Kelemen
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chemistry.chemical_classification ,chemistry ,Glycal ,Stereochemistry ,Organic Chemistry ,Thiol ,Stereoselectivity ,Reactivity (chemistry) ,General Chemistry ,Catalysis ,Ene reaction ,Coupling reaction - Published
- 2019
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47. Solid-state structure of pharmaceutically important coumarin derivatives from in-house collected XRPD data
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Tibor Eszenyi, Ákos Pogácsás, Nikoletta B. Báthori, and Attila Bényei
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Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Structural Biology ,General Materials Science ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Coumarin ,Biochemistry ,Solid state structure ,Powder diffraction ,Nuclear chemistry - Published
- 2019
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48. Out of cross-conjugation: the unexpected structure of tetrazinones
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Beatrix Bostai, András Kotschy, K. Lőrincz, A. Stirling, and Attila Bényei
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Steric effects ,Dipole ,Chemical physics ,Chemistry ,Computational chemistry ,General Chemical Engineering ,Single bond ,Molecule ,Aromaticity ,General Chemistry ,Cross-conjugation ,Ring (chemistry) ,Single crystal - Abstract
Detailed structural and computational investigations have been carried out to elucidate the unprecedented structural properties of NHC-derived tetrazinones. The provocative structural contradictions featured by this class of molecules as emerged from single crystal X-ray diffraction studies include the non-coplanar core ring system with an inter-ring C–C single bond indicating aromaticity but a pattern of bond alteration consistent with an overall quinoidal structure. Combination of periodic and gas-phase calculations identified two key factors affecting the overall structure. The first is a strong tendency to avoid cross-conjugation resulting in a coupled aromatic–quinoidal system whereas the second is the steric demand of the substituents determining the conformational behaviour of the rings. The peculiar electron distribution yields remarkably large polarizations and dipole moments for these molecules which can be key in their potential applications. more...
- Published
- 2014
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49. The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime
- Author
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Attila Sipos, Attila Bényei, Antal Udvardy, and Sándor Berényi
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Cyprodime ,Chemistry ,medicine.drug_class ,Stereochemistry ,Biological activity ,reduction ,General Chemistry ,Serotonergic ,cyprodime ,Materials Chemistry ,medicine ,oripavine ,10-deoxyaporphines ,acid-catalyzed rearrangement ,QD1-999 ,Opioid antagonist - Abstract
The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields. more...
- Published
- 2013
50. The dual role of cis-[RuCl2(dmso)4] in the synthesis of new water-soluble Ru(II)–phosphane complexes and in the catalysis of redox isomerization of allylic alcohols in aqueous–organic biphasic systems
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Attila Bényei, Antal Udvardy, and Ágnes Kathó
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Allylic rearrangement ,Aqueous solution ,Chemistry ,organic chemicals ,Organic Chemistry ,chemistry.chemical_element ,Biochemistry ,Medicinal chemistry ,Redox ,Ruthenium ,Catalysis ,Inorganic Chemistry ,Természettudományok ,Materials Chemistry ,Organic chemistry ,Physical and Theoretical Chemistry ,Kémiai tudományok ,Selectivity ,Single crystal ,Isomerization - Abstract
New air-stable, water-soluble Ru(II)–phosphane complexes were synthesized in high purity by the reaction of cis-[RuCl2(dmso)4] with 2 equivalents of 1,3,5-triaza-7-phosphaadamantane (pta) and its N-methyl and N-benzyl derivatives (pta-Me and pta-Bn, respectively). All new complexes were characterized by elementary analysis and spectroscopic methods (NMR, ESI-MS) and the molecular structures of cis-cis-trans-[RuCl2(dmso)2(pta)2], cis-cis-trans-[RuCl2(dmso)2(pta-H)2]Cl2 (obtained in acidic solutions) and that of cis-cis-trans-[RuCl2(dmso)2(pta-Me)2](CF3SO3)2 were determined by single crystal X-ray diffraction. Under mild conditions, cis-[RuCl2(dmso)4] actively catalyzed the transformation of allylic alcohols into the corresponding ketones with 100% selectivity while in the same reaction the new Ru(II)–pta complexes showed moderate activity and selectivity. more...
- Published
- 2012
- Full Text
- View/download PDF
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