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Showing 1 to 20 of 23 for “"Nitrone"”.
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Cyclic nitrones: oxidation studies and the synthesis of a heterocyclic nitrone
Part I: The synthesis of the heterocyclic nitrone, Δ³-dihydro-1,4-oxazine 4-oxide, by the oxidation of solutions of 4-hydroxymorpholine is described. The UV and IR spectra of the solutions were consistent with the structure proposed. Removal of the solvent gave linear polymers with the N-O-C …
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Interfacial Nitrone 1,3-Dipolar Cycloadditions for Modification of Monolayer Protected Gold Nanoparticles
… cycloaddition reaction with a series of nitrones under ambient and high-pressure conditions. Expanding the scope of this reaction to the investigation in synthesizing a nitrone modified-MPN and examine its ability to undergo the 1,3-dipolar cycloaddition reaction with a series of …
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The Design and Synthesis of Novel Chiral Z-Nitrones with Applications Towards the Syntheses of Enantiomerically Pure 4-Hydroxy Amino Acids
… via 1,3-dipolar cycloadditions of novel Z-nitrones and substituted olefins. Three achiral nitrones were synthesized in pursuit of a conformationally stable yet reactive Z-nitrone. The carboisopropoxynitrone was determined to be the best synthon in cycloadditions that favored a Z-nitrone …
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THE PHOTOISOMERIZATION OF 2-PHENYL-3H-INDOL-3-ONE N-OXIDE (2- PHENYLISATOGEN) TO 2-PHENYL-4H-3,1-BENZOXAZIN-4-ONE
The use of nitrones is an important synthetic tool for the organic chemist. An unusual reaction of these nitrones is a photochemical ring expansion under proper conditions that allows the nitrone oxygen to migrate past a carbon atom in a ring and insert itself into a ring that is expanded by the …
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Enantioenriched Homoaldol Products, Beta-Substituted Ketones, Isoxazolines, and Beta-Lactams Through Elaboration of Allylamine Asymmetric Homoenolate Equivalents: Synthesis and Elucidation of Reaction Pathways
A stereocontrolled intramolecular nitrone/olefin dipolar cycloaddition reaction of enantioenriched enals provides cyclopentyl isoxazoline products in 64--81% yields and with diastereomeric ratios of 78:22 to 84:16. An isoxazoline was converted into an enantiomerically pure beta-lactam via a …
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1-Aza-1'-Oxa(3,3)sigmatropic rearrangement: Synthesis of N-alkylindoles and 2,3-Dihydro-1h-Pyrrolo (1,2-A) Indole-9-Carboxylates
… with an arylhydroxylamine and reduction of the nitrone so formed with sodium cyanoborohydride. This procedure affords high yields of N-alkyl-N-arylhydroxylamines and is tolerant of a wide variety of substituents.
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Asymmetric Synthesis of Homotropinone and Tropane Alkaloids using Enantiopure Sulfinimines and the Synthesis and Applications of Methanoprolines
… sulfinimine-derived α,ß-unsaturated pyrrolidine nitrone was utilized in the development of a Lewis acid catalyzed [3+2] nitrone cycloaddition reaction for the asymmetric synthesis of the tropane alkaloid (+)-cocaine. The masked oxo sulfinimine was treated with an excess of the sodium enolate of …
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Integration Of Fermentation And Organic Synthesis: Studies Of Roquefortine C And Biosynthetic Derivatives
… synthesis of these compounds, namely through a nitrone-promoted transannular rearrangement. This type of internal rearrangement has never been carried out synthetically and would provide an efficient stereoselective synthesis of triazaspirocycles. This work encompasses efforts towards …
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Tandem Cycloaddition Chemistry: Part I. Synthesis and Crystallographic Analysis of 1-Azafenestranes. Part II. Synthesis and Reactivity of N-Vinyl Nitrones
… of a new type of heterodiene, the N-vinyl nitrone. The tandem [4+2]/[3+2] cycloaddition of a nitrocyclopentene was applied as the key step in the synthesis of c,c,c,c-[5.5.5.4]-1-azafenestrane·BH 3, which was completed in only 5 steps and 26% overall yield from 1-nitrocyclopentene. …
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Scope and stereochemistry of carbon-carbon bond formation via addition of carbon nucleophiles to nitrones
… and silyl ketene acetals to acyclic and cyclic nitrones have been studied. A 4:1 selectivity favoring axial addition was observed in the reactions of cis-3,5-dimethyl-2,3,4,5-tetrahydropyridine N-oxide with both methyl and phenyl Grignard reagents and the silyl ketene acetal of t-butyl acetate. …
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Alpha-Oxygenation by Acylation-Rearrangement of Nitrones
The acylation-rearrangement of N-alkylnitrones with acid chlorides and triethylamine affords a new method for the (alpha)-oxygenation of aldehydes and cyclic ketones via (alpha)-acyloxy imines. The reaction apparently proceeds by initial acylation of the nitrone oxygen, proton removal, and …
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Doubly Bonded Derivatives of Si and Ge: Cycloaddition Reactions and Polymer Chemistry
… Si, Ge) reactivity. The addition of a series of nitrone and nitro compounds to the group 14 (di)tetrelenes Mes2Si=SiMes2, Mes2Ge=GeMes2 and Mes2Ge=CH(CH2-t-Bu), was examined. In general, the addition of the 1,3-dipolar nitrogen oxides to the (di)tetrelene gave 5-membered ring adducts via a formal …
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Recherche et synthèse d'un piège à radicaux libres d'interet biologique: le (5-méthyl-1-oxyde-D-1-pyrrolin-5-yl) méthyl phosphonate diéthylique
… libres, le laboratoire SREP a développé une nitrone pyrrolidinique α-phosphorylée, la DEPMPO, dont les performances dans le piégeage des radicaux oxygénés (hydroxyle, superoxyde) s'avèrent supérieures à celles de la DMPO couramment utilisée. Dans le but de mieux cerner l'influence du …
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Computational Investigation of Spin Traps Using Hybrid Solvation Models.
<p>The cyclic nitrone 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), and the lesser known linear phenyl-N-tert-butylnitrone (PBN) and its phosphorylated analogues have been used as spin traps for the investigation of free radicals in biological systems. Theoretical work on these molecules suggests that …
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Photoassisted Generation of Complex N, O, S Polyheterocycles
… a [3+2] nitrile oxide addition, and a [3+2] nitrone cyclization. These reactions were applied first to a model system, and then to a new scaffold that contained the biologically relevant beta-lactam fragment.</p> <p>A summation of engineering work is also included to detail the development …
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Funktionalisierung von 6H-1,2-Oxazinen durch 1,3-dipolare Cycloadditionen und Halogenierungen
… ylides, diazoalkanes, azomethine ylides and a nitrone. High diastereoselectivity was observed, induced by the steric hindrance of the ethoxy group at the 6H-1,2-oxazines. The cycloadditions occur with high regioselectivity. In addition, the constitutions of the bicycles were predicted by the …
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Synthèse de Nouvelles Nitrones du Type Pyrroline-N-Oxyde et leur Utilisation en Spin-Trapping
… a récemment mis au point une nouvelle nitrone, le 2-diéthoxyphosphoryl-2-méthyl-3,4-dihydro- 2H-pyrrole-1-oxyde (DEPMPO), qui présente les avantages suivants par rapport au 2,2- diméthyl-3,4-dihydro-2H-pyrrole-1-oxyde (DMPO) couramment utilisé : meilleure persistance de l'adduit du …
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Chemical probes for the study of mitochondrial oxidative stress
… precursor ii. Three new pyridinium salt nitrone spin traps iv-vi, designed to accumulate in mitochondria, were synthesised using the Zincke reaction as the key pyridinium salt forming reaction. The compatibility of nitrones with the Zincke reaction was demonstrated for the first time. The …
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The chemistry of some organotellurium compounds
… experiments with PhCH=N(O)But (phenyl-t-butyl-nitrone) have provided evidence that the oxidative addition of an alkyl halide (RX=Mei, BunBr, BusecBr, ButBr, BrCH2-CH=CHCH2Br, and Br(CH2)4Br) to diphenyltelluride and reductive elimination of CH3SCN from Ph2(CH3)Te(NCS) proceeds via radical …
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