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Letteratura scientifica selezionata sul tema "Radicaux carbamoyles"

Autore: Grafiati

Pubblicato: 25 gennaio 2025

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Articoli di riviste sul tema "Radicaux carbamoyles"

Safiulina, A. M., A. V. Lizunov, E. I. Goryunov, G. V. Bodrin, I. B. Goryunova, T. V. Strelkova, M. S. Grigor'ev, V. K. Brel' e I. G. Tananaev. "Derivatives of (2-carbamoyl ethyl)diphenylphosphine oxides: synthesis and extraction properties with respect to actinides and lanthanides". Журнал неорганической химии 69, n. 1 (15 gennaio 2024): 99–109. http://dx.doi.org/10.31857/s0044457x24010124.

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Abstract (sommario):

A series of (2–carbamoyl ethyl)diphenylphosphine oxides (KFO) has been synthesized from commercially available reagents — diphenyl chlorophosphine and acrylamides. The influence of the number of ligand fragments of Ph2P(O)(CH2)2C(O), the nature of the oligoyl radical binding these fragments, as well as the presence of additional coordination centers in the KEFO molecule on the extraction properties of KEFO with respect to actinides and lanthanides was investigated. It was found that N,N′-methylene-bis[3-(diphenylphosphoryl) has the greatest efficiency in the extraction of actinidespropionamide] (III), in which two diphenylphosphorylpropionyl radicals are bound by a rigid HNCH2NH linker (the degree of extraction of U(VI) reaches ~73%, and Th(IV) — ~85%), while in the case of lanthanides, on the contrary, ligand V, containing the maximum amount of this kind of phosphoryl carbonyl radicals attached to a conformationally non-rigid nitrogenous heterocyclic matrix, as well as KEFO (II), containing an additional C=O group in an alkyl radical attached to a nitrogen atom, has significant advantages carbamoyl fragment (when using this compound, gadolinium extraction is close to 92%). The obtained data show that highly effective and selective extractants of both 4fand 5felements can be created on the basis of (2-carbamoyl ethyl)diphenylphosphine oxide structure.

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Xie, Long-Yong, Sha Peng, Li-Hua Yang e Xiao-Wen Liu. "Metal-Free Synthesis of Carbamoylated Chroman-4-Ones via Cascade Radical Annulation of 2-(Allyloxy)arylaldehydes with Oxamic Acids". Molecules 27, n. 20 (19 ottobre 2022): 7049. http://dx.doi.org/10.3390/molecules27207049.

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Abstract (sommario):

An efficient and straightforward approach for the synthesis of carbamoylated chroman-4-ones has been well-developed. The reaction is triggered through the generation of carbamoyl radicals from oxamic acids under metal-free conditions, which subsequently undergoes decarboxylative radical cascade cyclization on 2-(allyloxy)arylaldehydes to afford various amide-containing chroman-4-one scaffolds with high functional group tolerance and a broad substrate scope.

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Koshiishi, Ichiro, Kazunori Tsuchida, Tokuko Takajo e Makiko Komatsu. "Radical scavenger can scavenge lipid allyl radicals complexed with lipoxygenase at lower oxygen content". Biochemical Journal 395, n. 2 (28 marzo 2006): 303–9. http://dx.doi.org/10.1042/bj20051595.

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Lipoxygenases have been proposed to be a possible factor that is responsible for the pathology of certain diseases, including ischaemic injury. In the peroxidation process of linoleic acid by lipoxygenase, the E,Z-linoleate allyl radical–lipoxygenase complex seems to be generated as an intermediate. In the present study, we evaluated whether E,Z-linoleate allyl radicals on the enzyme are scavenged by radical scavengers. Linoleic acid, the content of which was greater than the dissolved oxygen content, was treated with soya bean lipoxygenase-1 (ferric form) in the presence of radical scavenger, CmP (3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl). The reaction rate between oxygen and lipid allyl radical is comparatively faster than that between CmP and lipid allyl radical. Therefore a reaction between linoleate allyl radical and CmP was not observed while the dioxygenation of linoleic acid was ongoing. After the dissolved oxygen was depleted, CmP stoichiometrically trapped linoleate-allyl radicals. Accompanied by this one-electron redox reaction, the resulting ferrous lipoxygenase was re-oxidized to the ferric form by hydroperoxylinoleate. Through the adduct assay via LC (liquid chromatography)–MS/MS (tandem MS), four E,Z-linoleate allyl radical–CmP adducts corresponding to regio- and diastereo-isomers were detected in the linoleate/lipoxygenase system, whereas E,E-linoleate allyl radical–CmP adducts were not detected at all. If E,Z-linoleate allyl radical is liberated from the enzyme, the E/Z-isomer has to reach equilibrium with the thermodynamically favoured E/E-isomer. These data suggested that the E,Z-linoleate allyl radicals were not liberated from the active site of lipoxygenase before being trapped by CmP. Consequently, we concluded that the lipid allyl radicals complexed with lipoxygenase could be scavenged by radical scavengers at lower oxygen content.

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Tang, Jia-Jun, Meng-Yang Zhao, Ying-Jun Lin, Li-Hua Yang e Long-Yong Xie. "Persulfate-Promoted Carbamoylation/Cyclization of Alkenes: Synthesis of Amide-Containing Quinazolinones". Molecules 29, n. 5 (25 febbraio 2024): 997. http://dx.doi.org/10.3390/molecules29050997.

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The incorporation of amide groups into biologically active molecules has been proven to be an efficient strategy for drug design and discovery. In this study, we present a simple and practical method for the synthesis of amide-containing quinazolin-4(3H)-ones under transition-metal-free conditions. This is achieved through a carbamoyl-radical-triggered cascade cyclization of N3-alkenyl-tethered quinazolinones. Notably, the carbamoyl radical is generated in situ from the oxidative decarboxylative process of oxamic acids in the presence of (NH4)2S2O8.

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Raviola, Carlotta, Stefano Protti, Davide Ravelli e Maurizio Fagnoni. "Photogenerated acyl/alkoxycarbonyl/carbamoyl radicals for sustainable synthesis". Green Chemistry 21, n. 4 (2019): 748–64. http://dx.doi.org/10.1039/c8gc03810d.

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Minisci, Francesco, Fausta Coppa e Francesca Fontana. "Reactivity of carbamoyl radicals: the first general and convenient free-radical synthesis of isocyanates". Journal of the Chemical Society, Chemical Communications, n. 6 (1994): 679. http://dx.doi.org/10.1039/c39940000679.

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Petersen, Wade F., Richard J. K. Taylor e James R. Donald. "Photoredox-catalyzed procedure for carbamoyl radical generation: 3,4-dihydroquinolin-2-one and quinolin-2-one synthesis". Organic & Biomolecular Chemistry 15, n. 27 (2017): 5831–45. http://dx.doi.org/10.1039/c7ob01274h.

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de Pedro Beato, Eduardo, Daniele Mazzarella, Matteo Balletti e Paolo Melchiorre. "Photochemical generation of acyl and carbamoyl radicals using a nucleophilic organic catalyst: applications and mechanism thereof". Chemical Science 11, n. 24 (2020): 6312–24. http://dx.doi.org/10.1039/d0sc02313b.

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An organic catalyst uses low-energy photons to generate acyl and carbamoyl radicals upon activation of the corresponding chlorides via a nucleophilic acyl substitution path. The synthetic potential and the mechanism of this strategy are discussed.

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Osmanoğlua, Şemsettin, Murat Aydın e M. Halim Başkana. "EPR of Gamma-irradiated L-Glutamine Hydrochloride and N-Carbamoyl-L-glutamic Acid". Zeitschrift für Naturforschung A 60, n. 7 (1 luglio 2005): 549–53. http://dx.doi.org/10.1515/zna-2005-0715.

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The electron paramagnetic resonance spectra of γ -irradiated L-glutamine hydrochloride and N-carbamoyl- L-glutamic acid single crystals have been investigated at room temperature. Radiation damage centres are attributed to ĊH, ṄH2 and CH2Ċ(NH2)COOH radicals.

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MINISCI, F., F. COPPA e F. FONTANA. "ChemInform Abstract: Reactivity of Carbamoyl Radicals: The First General and Convenient Free-Radical Synthesis of Isocyanates." ChemInform 25, n. 31 (19 agosto 2010): no. http://dx.doi.org/10.1002/chin.199431121.

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Più fonti

Tesi sul tema "Radicaux carbamoyles"

Badufle, Margaux. "Nouvelle méthode pour la synthèse d'acides N-aryloxamiques et applications". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0365.

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Ce manuscrit présente un nouveau procédé de synthèse d’acides oxamiques aromatiques et leur utilisation en tant que précurseurs de radicaux carbamoyles, pour promouvoir une chimie plus verte et plus sûre des isocyanates. La première étape de ce procédé consiste en une réaction de couplage croisé d’Ullmann-Goldberg entre un iodure d’aryle et un oxamate primaire. Son optimisation a mis en évidence l’influence significative du substituant de l’oxamate sur le rendement de la réaction, et différents modes de désactivation du catalyseur. Un grand nombre d’oxamates aromatiques ont ainsi été synthétisés, et plusieurs bis(oxamates) ont été obtenus, élargissant les possibilités d'utilisation de cette méthode pour la synthèse de polymères. Ensuite, quelques-uns de ces oxamates ont été déprotégés en milieu acide pour former les acides oxamiques correspondants. Par une décarboxylation oxydante en conditions thermiques ou photocatalytiques, ces derniers ont enfin été utilisés comme précurseurs de radicaux carbamoyles dans le cadre de deux applications : la génération in situ d’isocyanates par leur oxydation pour la synthèse d’uréthanes, et leur addition sur des imines pour la synthèse d’amides d’α-aminoacides
This manuscript describes a new process for the synthesis of aromatic oxamic acids and their use as carbamoyl radical precursors, aiming to promote a greener and safer chemistry of isocyanates. The first step of this synthesis consists in an Ullmann-Goldberg cross-coupling reaction between an aryl iodide and a primary oxamate. Its optimization highlighted the significant influence of the oxamate substituent on the reaction yield, and the different modes of catalyst deactivation. A large number of aromatic oxamates were synthesized, and several bis(oxamates) were obtained, expanding the potential use of this method for polymer synthesis. Subsequently, some of these oxamates were deprotected under acidic conditions to obtain corresponding oxamic acids. Through oxidative decarboxylation under thermal or photocatalytic conditions, the latter were finally used as carbamoyl radical precursors for two applications : the in situ generation of isocyanates through their oxidation for urethanes synthesis, and their addition to imines for the synthesis of α-aminoacid amides

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Carrière, Anne. "Cyclisations tandem de radicaux alpha-alcoxycarbonyle, alpha-carbamoyle et alpha-carbonyle : application à la synthèse de composés bicycliques". Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30084.

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La cyclisation de radicaux alpha-alcoxycarbonyle permet l'obtention de lactones. De meme, la cyclisation de radicaux alpha-carbamoyle et alpha-carbonyle conduit a des lactames et des cycloalcanones. Notre but etait de preparer des composes bicycliques via une cyclisation tandem de ces intermediaires radicalaires. Pour atteindre cet objectif, nous avons utilise diverses methodologies de production de ces radicaux a partir de precurseurs varies. La cyclisation oxydante d'esters allyliques actives ne permet d'obtenir ni des 2-oxo-3-oxa-bicyclo3. 1. 0hexanes ni des 2-oxo-3-oxa-bicyclo3. 3. 0octanes. La formation de 2-oxo-3-oxa-bicyclo3. 1. 0hexanes et de leurs analogues azotes a pu etre effectuee par la reduction d'alpha-dichloroesters ou amides avec cucl. Nous avons montre que l'enchainement d'une cyclisation radicalaire 5-exo avec la cyclopropanation d'un enolate de cuivre peut etre realisee sous ces conditions experimentales. Les memes composes peuvent etre prepares en deux etapes en utilisant, dans la deuxieme etape, de l'iodure de samarium comme agent reducteur. Le rearrangement de vinylcyclopropanes catalyse par le radical phenylthiyle conduit a des 2-oxo-3-oxa-bicyclo3. 3. 0octanes et a leurs analogues azotes. Les rendements et la chimioselectivite sont controles par la regio- et la stereoselectivite de la premiere cyclisation radicalaire. Les produits majoritaires sont des bicycles accoles a jonction cis, toutefois des bicycles a jonction trans ont ete isoles et caracterises. Nous avons montre que sous ces conditions experimentales, les cyclisations conduisant a des gamma-lactones et des gamma-lactames a partir de radicaux alpha-alcoxycarbonyle et alpha-carbamoyle stabilises ne sont pas reversibles. Le rearrangement de vinylcyclopropylcetones conduit a des bicyclo3. 2. 1octanones comme produit majoritaire, sauf dans le cas ou le radical alpha-carbonyle s'additionne sur une double liaison portant deux groupes methyle sur le carbone terminal

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Potin-Gautier, Martine. "Photoamidation d'olefines fluorees, en milieu homogene et en milieux microemulsions non aqueux". Toulouse 3, 1987. http://www.theses.fr/1987TOU30011.

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Les amides perfluores et mixtes (a doubles chaines hydrogenee et perfluoree) sont des precurseurs de tensioactifs susceptibles d'ameliorer les proprietes des mousses extinctrices, par diminution de la tension interfaciale entre l'eau et l'huile par un meilleur etalement de la mousse. Ces amides sont synthetises par photoamidation d'olefines : r::(f)-ch=ch::(2), r::(f)-ch=ch-r::(h), r::(f)-ch::(2)-ch=ch-r::(h) dans le t-butanol et dans des microemulsions de formamide

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Chan, Chien-Ching, e 詹前慶. "Substituent and Solvent Effects on Keto-Enol Tautomerism of Acetyl, Carbamoyl Derivatives, and Their Radical Cations". Thesis, 1999. http://ndltd.ncl.edu.tw/handle/41560203078684144988.

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碩士
國立清華大學
化學系
87
Abstract The results of DFT study of the substituent effects on molecular structures, relative stabilities, and mechanisms of intramolecular proton transfer in isolated acetyl and carbamoyl drivatives, for both neutral molecules and their radical cations, are reported. The reaction in the presence of one and two water molecules is also investigated. Furthermore, the effect of bulk water is considered for the system with two water molecules using the PCM continuum models. All of geometries of the local minima and transition states were optimized without symmetry restrictions at the B3YLP level of theory with D95++(d,p) basis sets and were verified by second derivative calculations. The DFT theory predicts the substituents with π-donating ability tend to reduce the energy barriers of enolization and ketonization in both drivatives and their radical cations. The relative stabilities of acetyl drivative tautomers exhibit that enolization is endothermic in the neutral molecules but exothermic in the radical cations. However, it shows that only endothermic process can be observed in carbamoyl drivative. The influence of water molecules largely reduce the barrier of the proton transfer by about 30 kcal/mol in striking contrast to the minor changes in the relative stability of keto and enol forms. In addition, the present of water molecules has the transfer of C-hydrogen or N-hydrogen onto the water-oxygen advance than the transfer of the hydrogen from this water to the oxygen of the acetaldehyde or formamide.

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Capitoli di libri sul tema "Radicaux carbamoyles"

"The Chemical Logic for Major Reaction Types". In Natural Product Biosynthesis, 22–46. The Royal Society of Chemistry, 2022. http://dx.doi.org/10.1039/bk9781839165641-00022.

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This chapter defines a core set of central metabolites that are thermodynamically activated but sufficiently stable kinetically to serve as diffusible molecules that power coupled reaction equilibria to drive biosynthesis in both primary and secondary pathways. Three such molecules are adenosine triphosphate (ATP), acetyl-coenzyme A (CoA), and the reduced nicotinamide coenzymes NADH and NADPH, which serve as cellular currencies for phosphoryl-, acetyl-, and electron transfers, respectively. ATP's thermodynamic activation arises from its kinetically stable side chain phosphoric anhydride linkages; acetyl-CoA from its acyl thioester grouping, and NAD(P)H from the dihydropyridinium ion linkage. S-Adenosylmethionine, with its activated sulfonium cation group, can transfer methyl, aminobutyryl, and adenosyl groups to cosubstrates as electrophilic or as radical fragments. Carbamoyl phosphate is a biologic carbamoylating reagent due to its mixed acyl phosphoric anhydride core. UDP-glucose and congeneric NDP-hexoses are fragmentable enzymatically into C1-glucosyl electrophiles for capture by cosubstrate nucleophiles. The delta 2- and 3-double bonds in isopentenyl-PP isomers serve as electrophilic and nucleophilic partners, respectively, for C–C bond-forming alkylations at the start of all isoprenoid biosynthetic pathways. Adenosine-5′-phosphosulfate is activated for sulfuryl group transfer via its mixed sulfuric-phosphoric acid side chain linkage. Molecular oxygen (O2) is kinetically stable enough to comprise 21% of Earth's atmosphere, but is thermodynamically activated to be the terminal electron acceptor in aerobic metabolism. Its controlled reductive cleavage is the driving force for introduction of diverse oxygen functional groups in a plethora of natural product maturations.

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