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Ether Derivatives (ether + derivative)

Distribution by Scientific Domains

Chemistry	92%

Selected Abstracts

Phase-Transfer-Catalyzed Intramolecular Cyclization of ortho -Alkynyl Phenyl Ether Derivatives for Synthesis of 2,3-Disubstituted Benzo[b]furans

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010
Jie Hu
Abstract A variety of substituted benzo[b]furans are readily prepared in good to excellent yields under the mild reaction conditions from o -(1-alkynylphenoxy)-1-phenylethanone under phase-transfer catalysis (PTC). This methodology accommodates simple experimental operations, inexpensive and environmentally benign catalysts, metal catalyst-free conditions, facile reagents and the possibility to conduct large-scale preparations. The development of carbon-carbon bond formation processes via an overall structural isomerization represents the most atom-economical approach. [source]

ChemInform Abstract: Regiodivergent Carbometalation Reactions of Ynol Ether Derivatives.

CHEMINFORM, Issue 22 2010
Anat Levin
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Search for Histamine H3 Receptor Antagonists with Combined Inhibitory Potency at N, -Methyltransferase: Ether Derivatives.

CHEMINFORM, Issue 22 2005
J. Apelt
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Chirally Modified Platinum Generated by Adsorption of Cinchonidine Ether Derivatives: Towards Uncovering the Chiral Sites

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007
Norberto Bonalumi
Abstract The adsorption behavior of O -methyl and O -trimethylsilyl derivatives of cinchonidine (CD), employed as chiral modifiers for heterogeneous enantioselective hydrogenations on supported Pt catalysts, has been investigated by using attenuated total reflection infrared spectroscopy (ATR-IR) and density functional theory (DFT) electronic structure calculations. The ATR-IR spectroscopic investigation provided detailed insight of the adsorbed modifiers under conditions close to those employed during catalytic processes, and electronic structure calculations were used as a complement to the experiments to uncover the implications of conformational changes in generating the topology of the surface chiral site. The structural investigation of the adsorbed modifiers revealed a relationship between the spatial positions of the ether substituents and the enantiodifferentiation induced by the modified catalyst observed in the hydrogenation of ,-activated ketones. Experiments and calculations corroborate a model, according to which the addition of a bulky ether group to CD reshapes the chiral sites, thus generating catalytic chiral surfaces with different and, in some cases (e.g. hydrogenation of ketopantolactone), even opposite enantioselective properties to those obtained with CD without altering the absolute configuration of the modifier. The study also confirms that active surface conformations of cinchona modifiers are markedly different from those existing in vacuum and in solution, thus underlying the necessity of investigating the surface-modifier interaction in order to understand enantioselectivity. [source]

Synthesis and Electrochemical Properties of Tetrasubstituted Tetraphenylethenes

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2006
Alina Schreivogel
Abstract Tetrakis(4-acetoxyphenyl and 4-benzoyloxyphenyl)ethenes 1f and 1g were obtained by acylation of tetrakis(4-hydroxyphenyl)ethene 1b. Ullmann etherification of 4,4,-dihydroxybenzophenone 2b and subsequent McMurry coupling yielded tetrakis(phenoxyphenyl)ethene 1i. The tetrakis(acetamidophenyl)ethene 1h was prepared in three steps from tetraphenylethene 1c by nitration, Raney-Ni reduction and subsequent acetylation. Alternatively, trifluoroacetamide 1j, 2-methylhexanamide 1k and 2,4-dimethylbenzamide 1l, with less tendency to form 2D hydrogen bonding networks and thus increased solubility as compared to 1h, were prepared by acylation of 4,4,-diaminobenzophenone 2a and subsequent McMurry coupling. Compounds 1f,l were investigated by cyclic voltammetry. While the phenyl ether derivative 1i displays single-electron processes during oxidation, a two-electron process was discovered for trifluoroacetamide 1j as was also supposed for the esters 1f and 1g. In addition, comproportionation constants were shown to be dependent on the solvent. In situ IR spectroelectrochemistry provided evidence for quinoidal type substructures in the dioxidized forms of tetraphenylethenes 1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Absorption and fluorescence properties of acridinones, thioacridinones, aminoacridines and related crown ethers

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2001
Anne-Marie Patellis
We report a study on the absorptive and emissive properties of 9-acridinones, 9-thioacridinones and 9-aminoacridines including six crown ether derivatives. The effect of solvents and of the addition of cations (Na+, K+, Ca2+ and Mg2+) on these properties has been studied. The absorption of the crown ether derivative of 9-thioacridinone is sensitive to solvents while the fluorescence of crown ethers derived from 9-aminoacridines shows some specificity towards cations. Empirical modeling was used to discuss the emission characteristics of these compounds. [source]

Structure elucidation, conformational analysis and thermal effects on membrane bilayers of an antimicrobial myricetin ether derivative

JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2001
C. Demetzos
The membrane perturbing 3,7,4,,5,-tetramethyl ether of myricetin 1 was isolated from Cistus monspelien-sis L. Its structure was elucidated and its conformational properties were explored using a combination of 2D NMR spectroscopy and computational chemistry. The obtained results showed that compound 1 adopts four enantiomeric pairs of low energy conformers characterized: (a) by an aromatic ring B twisted through rotation about C2-C1, bond from the rigid isoflavone ring; (b) a 4,-O-CH3 bond oriented out of the plane with equal probability upwards or downwards the phenyl ring B, while all the other O-CH3 bonds are oriented in the plane of the aryl ring. Two of these enantiomeric pairs are lowest in energy. These possible bioactive con-formers are possibly stabilized by van Der Waals interactions. The 3,,5-diacetyl derivative 2 of compound 1 was synthesized and its structure elucidation was achieved based on the chemical shift assignment of the parent compound 1. The Differential Scanning Calorimetry (DSC) results revealed that the degree of the thermal effects exerted by the flavonoids at dipalmitoylphosphatidyl choline (DPPC) bilayers followed the order 1 > 2 > myricetin. Their antimicrobial activity against Gram positive bacteria followed the same order. [source]

Design and synthesis of chemiluminescent substrates with high luminescent efficiency in an aqueous system: 5- tert -butyl-4,4-dimethyl-2,6,7-trioxabicyclo[3.2.0]heptanes bearing a 3-hydroxy-4-(1-iminoethyl)phenyl moiety at the 1-position

LUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 4 2001
Masakatsu Matsumoto
Abstract A CIEEL-active dioxetane bearing a 4-acetyl-3-hydroxyphenyl moiety has very recently been found to emit light effectively, even in an aqueous system, albeit with a very slow CIEEL decay rate. As an attempt to improve the CIEEL decay rate of this type of dioxetane, three dioxetanes, in which a carbonyl in the 4-acetyl-3-hydroxyphenyl moiety was modified into an oxime, oxime O -methyl ether, or semicarbazone, were synthesized. These three dioxetanes decomposed to emit light far more rapidly than the parent 4-acetyl-3-hydroxyphenyl-substituted dioxetane. Among them, a dioxetane bearing a 3-hydroxy-4-(1-methoxyiminoethyl) phenyl, namely an oxime O -methyl ether derivative, gave high chemiluminescent efficiency. As for a semicarbazone derivative, decrease of the chemiluminescent yield was minimal, even in an aqueous system. Copyright © 2001 John Wiley & Sons, Ltd. [source]

An Efficient Synthesis of Substituted meta -Halophenols and Their Methyl Ethers: Insight into the Reaction Mechanism

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2010
Faiz Ahmed Khan
Abstract An expeditious synthetic methodology leading to substituted meta -halophenols and their corresponding methyl ether derivatives through acid-mediated fragmentation of suitably substituted dihalonorbornyl ketones has been devised. The reaction sequence consists of TBTH-mediated (TBTH is tri- n -butyltin hydride) selective bridgehead halogen reduction of easily accessible Diels,Alder adducts derived from 1,2,3,4-tetrahalo-5,5-dimethoxycyclopentadiene and ,-substituted vinyl acetates, with subsequent conversion into the requisite bicyclic ketones by a two-step hydrolysis/oxidation approach. An extensive mechanistic investigation based on isotope labeling and cross experiments has been carried out and plausible mechanistic pathways based on these results have been proposed. The absence of halogen atoms at the bridgehead positions steers the reaction through a novel pathway involving the incorporation of proton (or deuterium) followed by elimination of HX (or DX), so the described methodology also provides a reliable route to ortho-para dideuteratedphenolic derivatives. [source]

Radical Addition of Ethers to Terminal Alkynes with High E -Selectivity

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 30 2009
Zili Chen
Abstract Direct radical additions of ethers to terminal alkynes were investigated by using Me2Zn/O2 as radical initiator to afford 2-vinyl ether derivatives with high E -selectivity, while reversed E/Z selectivity is obtained with Et3B/O2. Two competitive pathways are suggested for the formation of vinyl radical B: zinc-radical exchange (route a) followed by protonation provides E -configuration products exclusively through Zn(II) complexation. Hydrogen abstraction by vinyl radicals (route b) yields mainly Z isomers.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Absorption and fluorescence properties of acridinones, thioacridinones, aminoacridines and related crown ethers

Analysis of alcohols, as dimethylglycine esters, by electrospray ionization tandem mass spectrometry

JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2001
Dr David W. Johnson
Abstract Dimethylglycine (DMG) esters are new derivatives for the rapid, sensitive and selective analysis of primary and secondary alcohols, in complex mixtures, by electrospray ionization tandem mass spectrometry (ESI-MS/MS). Their development was inspired by the use of the complementary dimethylaminoethyl esters for the trace, rapid analysis of fatty acids. DMG esters are simply prepared by heating a dichloromethane solution of the imidazolide of dimethylglycine, containing triethylamine, and an alcohol. DMG esters of long-chain fatty alcohols, isoprenoidal alcohols and hydroxy-acids are analysed by electrospray ionization tandem mass spectrometry with a precursor ion of m/z 104 scan. Diols, glyceryl esters, glyceryl ethers and some sterols are analysed by a neutral loss of 103 Da scan. Trimethylglycine (TMG) ester iodides, prepared by alkylation of DMG esters with methyl iodide, are more sensitive derivatives for molecules containing secondary alcohol groups, such as cholesterol and gibberellic acid. They are analysed by a precursor ion of m/z 118 scan. DMG or TMG derivatives were shown to be at least comparable and sometimes an order of magnitude more sensitive than N -methylpyridyl ether derivatives for ESI-MS/MS analysis of the different classes of alcohols. Applications of these derivatives for the diagnosis of inherited disorders and the analysis of natural products are presented. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Synthesis and characterization of ether derivatives of brominated poly(isobutylene- co -isoprene)

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2006
Sergio A. Guillén-Castellanos
Abstract Variations of the Williamson ether synthesis were employed to prepare a range of new derivatives of brominated poly(isobutylene- co -isoprene) (BIIR). Unambiguous characterization of the polymeric products was accomplished by spectroscopic comparisons to low-molecular-weight analogues derived from brominated 2,2,4,8,8-pentamethyl-4-nonene, which served as a model for the reactive functionality found within BIIR. The substitution of bromide from BIIR occurred at moderate temperatures with stoichiometric amounts of quaternary ammonium phenoxide to yield O-alkylation products in high yields. Simple mixtures of BIIR, KOH, and aliphatic alcohols generated the desired allylic ethers when heated above 110 °C in the absence of quaternary ammonium salts. Knowledge gained from these small-molecule alkylations was used to prepare graft copolymers from BIIR and poly(ethylene oxide) through the exploitation of the apparent ability of polyethers to activate potassium alkoxides in nucleophilic substitutions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 983,992, 2006 [source]

Synthesis and Antineoplastic Activity of O -Alkylated Derivatives of 7-Hydroximinoandrost-5-ene Steroids

ARCHIV DER PHARMAZIE, Issue 7 2010
Ranju Bansal
Abstract Varied positioning of the hydroximino group on the parental steroid skeleton results in remarkable changes in the antineoplastic activity profile of the compounds. Here, the compound 7-oximino-5-androstene and its O -alkylated derivatives have been prepared and screened for cytotoxic and aromatase inhibitory activity. The steroidal 7-oximino ether derivatives exhibited insignificant cytotoxic effects when screened against three cancer cell lines, MCF-7 (breast), NCl-H460 (lung), and SF-268 (CNS) at 100 ,M. However, the imidazolyl-substituted steroidal oxime ethers displayed moderate inhibition of cytochrome P450 aromatase. [source]