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Showing 1 to 20 of 63 for “"Aromatic Substitution"”.
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Nucleophilic aromatic substitution of metallabenzenes
… a new benzenelike reaction - nucleophilic aromatic substitution of hydrogen (SN H) (Scheme 0-1). In this process, the nucleophile (Nu) first attacks the cationic metallabenzene (A) at the γ position to the neutral metallacyclohexadiene compound (B). Oxidation with an external oxidant [O] …
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Reinventing Aromatic Substitution: A Novel Look
<p>Electrophilic aromatic substitution (EAS) and directed <em>ortho</em>-metalation (DoM) involve the direct substitution of an arene hydrogen. A major drawback involving EAS is the necessity for harsh forcing conditions for the reaction to proceed. Catalysts such as Lewis acids FeBr<sub>3</sub> …
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Molecular Orbital Calculations on Electrophilic Aromatic Substitution
… point during the course of an electrophilic aromatic substitution reaction. Although the calculations were made using a proton as an electrophile, the method should be applicable to other electrophiles with only slight modification. A modification of the Pariser-Parr-Pople technique was …
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PART I PREPARATION OF NOVEL LACTONES AND THEIR PRECURSORS DERIVED FROM METHYL SALICYLATE PART II NUCLEOPHILIC AROMATIC SUBSTITUTION IN A DINITROSALICYLIC LACTONE WITH RING OPENING AND ELIMINATION VIA MEISENHEIMER INTERMEDIATES
… described. The influence of substituents on the aromatic nucleus in affecting ring closure reactions was examined. Experimental results show that ring closure is enhanced when nitro groups are incorporated in the aromatic ring. Investigations were conducted in the preparation of compounds …
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Directed Ortho-Metalation of Dimethylarylamines
… can be synthesized directly, i.e., by substitution of a proton, using either of two procedures: electrophilic aromatic substitution (EAS) or directed ortho-metalation (DoM). Directed ortho-metalation (DoM) is an alternative aromatic substitution process initiated by organolithium …
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Interactions of Nitrated Aromatics With Electron Rich Species: Chiral and Achiral
… of the first enantioselective nucleophilic aromatic substitution reactions.
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Utilization of Rationally Designed Small Molecule Chiral Selectors in Novel Enantioselective Processes
… racemic amides containing electron-deficient aromatic moieties are described. The method revolves around forming Meisenheimer adducts which are stabilized by quaternary ammonium salts in a nonpolar medium. When run in the presence of a chiral selector, one enantiomer is effectively shielded …
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Synthesis of indoles via a tandem benzannulation-cyclization strategy
… the second step in this tandem strategy included aromatic substitution, palladium-catalyzed oxidative amination, and nucleophilic cyclization. This thesis discusses the scope and limitations of this tandem strategy.
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On the way to molecular optical switches : a solid state NMR study of trans-cinnamic acids
… In this work, the influence of polymorphism and aromatic substitution on the photoreaction of cinnamic acid is studied. For this purpose several cinnamic acid derivatives have been chosen, starting with the two photoactive cinnamic acid polymorphs, alpha and beta. Within the alpha-polymorphs, …
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Metalation of the Di- and Tri-Methoxybenzenes
… 1,2,3-system affords an interesting nucleophilic aromatic substitution reaction. This autocatalytic mode of ortho-metalation offers additional insight into the controversy regarding the participation of a dimer intermediate in the mechanism of the directed ortho-metalation reaction.
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Directed Ortho-Metalation of the Three Methyl Anisoles in Various Media
… is a very useful alternative to electrophillic aromatic substitution (EAS) for the synthesis of substituted aromatic compounds. DoM is highly regiospecific providing metalation chiefly in the ortho-position. However, lateral (a-) metalation of an alkyl side-chain and ortho-metalation of a second …
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Synthesis of pyridines via [4 + 2] cycloadditions of vinylallenes with azadienophiles
… of these 2- sulfonylpyridines via nucleophilic aromatic substitution reactions. Overall, annulation strategies based on [4 + 2] cycloadditions of vinylallenes with azadienophiles have been developed for the preparation of highly substituted pyridines in an efficient, convergent, and …
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Synthesis, properties, and modifications of engineering polymers
… systematically synthesized via nucleophilic, aromatic substitution reactions using the potassium carbonate/N-methylpyrrolidone synthesis route. In particular, deuterated poly(arylene ether sulfones) were synthesized in order to investigate molecular motion via deuterium NMR. The mechanical, …
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The SRN1 reactivity of halobenzenesulfonamides and related compounds
… investigation of the application of nucleophilic aromatic substitution by the SRN 1 mechanism of halobenzenesulfonamides and related compounds towards the synthesis of 1,2-benzothiazine I,I-dioxides is reported. 3-Substituted and 3,4- disubstituted 2<i>H</i>-l,2-benzothiazine l,l-dioxides were …
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Synthesis of poly(arylene ether sulfone)-polyimide segmented copolymers
… oligomers have been synthesized by nucleophilic aromatic substitution using potassium carbonate as base and N-methyl pyrrolidinone (NMP) as solvent. m-Aminophenol was used as an endcapper to control the molecular weight of the oligomers and to provide functional amine termination. These amine …
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Synthesis of Chiral Benzimidazolylidenes from 1,10-Phenathrolines and 1,10-Phenathroline-2,9-dione /
… 2,9- position of phenanthroline by nucleophilic aromatic substitution, followed by a reduction-resolution sequence; and 3) use of the protected octahydrophenanthroline as a substrate for chiral induction a to nitrogen.
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Synthesis and Characterization of Phosphorus Containing Poly(arylene ether)s
… thermoplastics. Phosphorus containing activated aromatic dihalides and bisphenols were synthesized in high purity. These monomers were successfully polymerized via nucleophilic aromatic substitution to afford high molecular weight polymers. It was determined that by incorporating the phosphine …
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Macrocyclic Monomers: Synthesis, Characterization and Ring-opening Polymerization
… of macrocycles were synthesized by nucleophilic aromatic substitution cyclization reactions under pseudo-high dilution conditions. Pure individual macrocycles as well as cyclic mixtures were characterized by NMR, HPLC, GPC, FABMS, MALDI-TOF-MS, DSC and TGA. Comparison study suggests that the …
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Functional Activity and Switching of Novel Cannabinergic Ligands
… analogues, we have shown that presence of an aromatic substitution at C-1' imparts a CB1 agonist, CB2 antagonist. This is a unique mechanism and one of the first examples of an agent with dual affinity and opposing activity.</p> <p>In the triaryl series of compounds, more insight is gained for …
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Palladium-Imidazolium Carbene Catalyzed Heck Coupling Reactions and Synthesis of a Novel Class of Fluoroanthracenylmethyl PTC Catalysts
… the challenging electron-deficient electrophilic aromatic substitution step. These new catalysts proved to have high selectivities for glycine alkylation under mild conditions.</p>
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