Home About us Contact
|
Home About us Contact | ||
|
|
||
Methoxy
Terms modified by Methoxy Selected AbstractsSynthesis of Hexabromo, Hydroxy, Epoxy, Methoxy and Nitroxy Derivatives of Tetralins and Naphthalenes.CHEMINFORM, Issue 7 2005Ramazan Erenler No abstract is available for this article. [source] Synthesis of Methoxy and Hydroxy Containing Tetralones: Versatile Intermediates for the Preparation of Biologically Relevant Molecules.CHEMINFORM, Issue 34 2003Anjan Ghatak Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis and crystal structure determination of 6,7-dihydro-2-methoxy-4-(substituted)-5H -benzo[6,7]cyclohepta[1,2- b ]pyridine-3-carbonitrileCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2007A. M. Moustafa Abstract The compounds 6,7-dihydro-2-methoxy-4-(4-methylphenyl)-5H -benzo[6.7]cyclohepta[1,2 -b ]pyridine-3-carbonitrile (compound IIIa) and 4-(4-chlorophenyl)-6,7-dihydro-2-methoxy-5H -benzo[6,7]cyclohepta[1,2- b ]pyridine-3-carbonitrile (compound IIIb) were synthesized and their structures have been determined from three dimensional X-ray data using direct method and refined by full matrix least squares with anisotropic thermal parameters for non-hydrogen atoms to conventional R(gt) of 0.036 and 0.038 for the two compounds respectively. For compound (IIIa) the crystals are monoclinic, space group Cc, with a=11.2909 (5) Å, b=17.7755(8) Å, c=9.1437(4) Å and ,=95.428(3)°, while the crystals of the second compound (IIIb) are triclinic, space group P1, with a=8.7465(3)Å, b=10.3958(3)Å, c=10.9011(4)Å, ,= 108.3870(10)°, ,=101.3741(12)°, ,=97.9594(12)°. The molecular structure of the two compounds have nearly the same configuration, where the cyclohepta ring takes the boat shape and the methoxy and the carbonitrile groups are attached at the same position C2 and C8. The difference occurs only at the position C4, where the substituent is methylphenyl for compound (IIIa) and chlorophenyl for the other. The bond lengths, valency angles and the hydrogen bonding were calculated and fully discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Rh(I) and Pd(II) complexes of methoxy functionalized heterocyclic carbene: Synthesis and characterizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2006M. E. Günay Abstract A new methoxy functionalized 2-(trichloromethyl)-1,3-diarylimidazolidin (6) was synthesized as the precursor for N-heterocyclic carbene complexes of Pd(II) and Rh(I) by the condensation of N,N'-bis(2,4-dimethoxyphenyl)-1,2-diaminoethane with chloral. The structures of all compounds have been elucidated by a combination of multinuclear NMR spectroscopy, elemental analysis and in one instance, by single crystal X-ray diffraction. Compound 8, C27H34N2O4ClRh, crystallizes in the triclinic space group P-1 with cell dimensions a = 9.7642(12)Å, b = 11.1914(11)Å, c = 13.0102(14)Å, , = 104.034(9)°, , = 106.658(9)°, , = 99.658(9)° with Z = 2. The molecular structure of 8 shows the geometry around the Rh metal to be a slightly distorted square planar. The crystal structure shows the formation of centrosymmetric dimers via intermolecular C-H...Cl hydrogen bonds. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Capillary electrophoresis of liposomes functionalized for protein bindingELECTROPHORESIS, Issue 20 2006Gerhard Bilek Abstract CE enabled assessing the attachment of hexa-histidine-tagged proteins to functionalized phospholipid liposomes. The liposomes were made of 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphocholine, phosphatidyl-ethanolamine, cholesterol and distearoyl-glycero-3-phosphoethanolamine- N -methoxy(polyethylene glycol) in a molar ratio of 29:26:40:5. The unilamellar vesicles, which had an average diameter of 170,nm, were labelled by inclusion of FITC-dextran for fluorescence detection. CE was carried out in poly(vinyl alcohol) (PVA)-coated capillaries at 25°C with a BGE consisting of Tris-HCl (50,mM, pH,8.0). For conjugation of the liposomes with the proteins (soluble synthetic receptor fragments with molecular mass of 60 and 70,kDa, respectively), Ni2+ was implanted into the vesicle surface by an anchor lipid containing a nitrilotriacetate acid (NTA) group as complexation agent for the metal ions. The difference in surface charge enabled the separation of the different species of interest by CE: plain vesicles, vesicles functionalised with Ni-NTA, vesicle,protein complexes and the species formed upon removal of the Ni-ions by complexation with EDTA. Loss of the Ni-ions resulted in the release of the proteins and the reappearance of the plain Ni-free NTA-liposome species in the electropherograms. [source] Chiral ion-exchange capillary electrochromatography of arylglycine amides with dextran sulfate as a pseudostationary phaseELECTROPHORESIS, Issue 4-5 2005Yi Chen Abstract A low-cost tunable chiral ion-exchange capillary electrochromatographic method has been developed for the separation of arylglycine amide racemic mixtures with dextran sulfate (DS) as an anionic and chiral pseudostationary phase and Tris-tartrate as a buffer system. The concentrations of DS and Tris had opposite influences on retention and resolution and could serve as ideal factors to finely tune the running speed and chiral resolution. Tartrate and pH largely impact the separation but pH should be confined within 3.0,5.5, only suitable for coarse tuning, while tartrate was preserved as the key buffering reagent, normally maintained at 40 mmol/L. With a working system composed of 0.1,1.0% DS, 20,60 mmol/L Tris, and 40 mmol/L tartrate at pH 3.50,4.50, the enantioresolution of arylglycine amides was shown to be dependent on their chemical structure: The chiral resolution increased when the hydrogen at the ,-amino group or at the p -position of phenyl ring was replaced by other larger group(s) but the resolution decreased when the group at the o- or m- site on the phenyl ring was enlarged. Further, the electronegative substitute of -Cl had larger resolution increment than methyl or methoxy at the position p- of phenyl ring but much lower increment at position m- . It is possible to well explain the resolution variation phenomenon by considering the group resistance and the variation of hydrogen-bonds formed inside the amino amides and between the solutes and DS. The amido group was shown irreplaceable to have chiral resolution with DS alone as an ionic and chiral pseudostationary phase. [source] Sponge halogenated natural products found at parts-per-million levels in marine mammalsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2002Walter Vetter Abstract Several unknown, abundant brominated compounds (BCs) were recently detected in the blubber of dolphins and other marine mammals from Queensland (northeast Australia). The BCs were interpreted as potential natural products due to the lack of anthropogenic sources for these compounds. This study investigated whether some of the BCs accumulated by diverse marine mammal species are identical with natural BCs previously isolated from sponges (Dysidea sp.) living in the same habitat. Isolates from sponges and mollusks (Asteronotus cespitosus) were compared with the signals detected in the mammals' tissue. Mass spectra and gas chromatography retention times on four different capillary columns of the isolates from sponges and mammals were identical in all respects. This proves that the chemical name of the compound previously labeled BC-2 is 4,6-dibromo-2-(2,,4,-dibromo)phenoxyanisole and that the chemical name of BC-11 is 3,5-dibromo-2-(3,,5,-dibromo,2,-methoxy)phenoxyanisole. Using a quantitative reference solution of BC-2, we established that the concentrations of the brominated metabolites found in the marine mammals are frequently >1 mg/kg. The highest concentration (3.8 mg/kg), found in a sample of pygmy sperm whale (Kogia breviceps), indicates that BC-2 is a bioaccumulative, natural organohalogen compound. This is supported by the concentrations of the BCs in our samples being equal to the highest concentrations of anthropogenic BCs in any environmental sample. The quantitative determination of BC-2 in blubber of marine mammals from Africa and the Antarctic suggests that BC-2 is widespread. These results are direct proof that marine biota can produce persistent organic chemicals that accumulate to substantial concentrations in higher trophic organisms. [source] Nucleophilic Addition of Water and Alcohols to Dicyanonitrosomethanide: Ligands with Diverse Bonding Modes in Magnetically Coupled d-Block ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2010Anthony S. R. Chesman Abstract Ligands resulting from the transition-metal-promoted nucleophilic addition of water or an alcohol to dicyanonitrosomethanide ions (dcnm) have been utilised in the formation of a large series of polynuclear complexes. Addition of water to dcnm results in formation of carbamoylcyanonitrosomethanide (ccnm); deprotonation of this ligand gives amidocarbonyl(cyano)nitrosomethanide (acnm), which has been incorporated into the trinuclear complex [Cu3(acnm)2(dmae)2(H2O)2] [dmae = 2-(dimethylamino)ethoxide] (1) which shows strong antiferromagnetic coupling with an exchange coupling constant, J = ,500 cm,1. [Cu(acnm)(NH3)2], (2) marks the first instance of acnm facilitating the formation of a coordination polymer, namely a 1D chain with intramolecular hydrogen bonding. Attempts to synthesise 2 through different reaction conditions instead resulted in the mononuclear [Cu(acnm)(NH3)2(py)] (py = pyridine) (3). The addition of ethanol to dcnm results in cyano[imino(ethoxy)methyl]nitrosomethanide (cenm) which features in the mononuclear [Cu(cenm)2(H2O)2] (4) and polymeric {[Cu(cenm)2]2·H2O}, (5). The latter is the first example of the cenm ligand in a coordination polymer and has a highly unusual coordination mode through the nitrile groups and extremely weak antiferromagnetic coupling. {[Mn3(ccnm)2(EtOH)2(OAc)4]·2EtOH}, (6) and (Et4N)2[Cu(ccnm)4] (7) contain previously unobserved coordination modes of the ccnm ligand while the complex [Mn(cmnm)3Mn(bipy)(MeOH)](ClO4) (8) {cmnm = cyano[imino(methoxy)methyl]nitrosomethanide, bipy = 2,2,-bipyridine} displays weak antiferromagnetic coupling between manganese atoms with J = ,1.44 cm,1. A change in the solvent systems used in the synthesis of 7 results in the formation of the mononuclear complexes [Mn(bipy)2(dcnm)2] (9) or [Mn(bipy)2(H2O)(dcnm)](dcnm)·H2O (10) and [Mn(bipy)2(dcnm)(H2O)](dcnm) (11). The addition of ethlyene glycol monomethyl ether to dcnm gives cyano[imino(2-methoxyethoxy)methyl]nitrosomethanide (cgnm) and the formation of [Cu(cgnm)2(H2O)2] (12). [source] Pseudo-Octahedral Schiff Base Nickel(II) Complexes: Does Single Oxidation Always Lead to the Nickel(III) Valence Tautomer?EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2008Olaf Rotthaus Abstract With the aim of establishing correlations between the ligand structure and the oxidation site in nickel complexes from Schiff base ligands, five ligands and their nickel complexes have been synthesized. The prototypical asymmetric Schiff base ligand HL1 contains both phenol and pyridine pendant arms with a pivotal imine nitrogen atom. Ligands HL2,5 differ from HL1 by either their phenolate para substituent, the hybridization of the pivotal nitrogen atom, and/or the N-donor properties of the pyridine moiety. The five complexes [Ni(L1,5)2] are obtained by treating the corresponding ligands with 0.5 equiv. of Ni(OAc)2·4H2O in the presence of NEt3. X-ray crystal-structure diffraction studies as well as DFT calculations reveal that [Ni(L1,5)2] involves a high-spin nickel(II) ion within a pseudo-octahedral geometry. The two ligands are arranged in a meridional fashion when the pivotal nitrogen atom is an imine {as in [Ni(L1,2)2] and [Ni(L4,5)2]}, while the fac isomer is preferred in [Ni(L3)2] (amino pivotal nitrogen atom). [Ni(L1)2] is characterized by an oxidation potential at ,0.17 V vs. Fc+/Fc. The one-electron-oxidized species [Ni(L1)2]+ exhibits an EPR signal at g = 2.21 attributed to a phenoxyl radical that is antiferromagnetically coupled to a high-spin NiII ion. [Ni(L2)2] differs from [Ni(L1)2] by the phenolate para substituent (a tert -butyl instead of the methoxyl group) and exhibits an oxidation potential that is ca. 0.16 V higher. Compared to [Ni(L1)2]+ the cation [Ni(L2)2]+ exhibits a SOMO that is more localized on the metal atom. The EPR and electrochemical signatures of [Ni(L3)2]+ are similar to those of [Ni(L1)2]+, thus showing that an imino to amino substitution compensates for a methoxy to tert -butyl one. Replacement of the pyridine by a quinoline group in [Ni(L4,5)2] makes the complexes slightly harder to oxidize. The EPR signatures of the cations [Ni(L4,5)2]+ are roughly similar to those of the pyridine analogs [Ni(L1,2)2]+. The oxidation site is thus not significantly affected by changes in the N-donor properties of the terminal imino nitrogen atom.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Oxime Carbonates: Novel Reagents for the Introduction of Fmoc and Alloc Protecting Groups, Free of Side ReactionsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010Sherine N. Khattab Abstract Fmoc and Alloc protecting groups represent a consistent alternative to classical Boc protection in peptide chemistry. The former was established in the last decades as the ,-amino protecting group of choice, whereas the latter allows a fully orthogonal protection strategy with Fmoc and Boc. Usually, the introduction of the Fmoc and Alloc moieties takes place through their halogenoformates, azides, or activated carbonates. This rather simple reaction is accompanied by several side reactions, specially the formation of Fmoc/Alloc dipeptides and even tripeptides. The present work describes new promising Fmoc/Alloc-oxime reagents, which are easy to prepare, stable, and highly reactive crystalline materials that afford almost contaminant-free Fmoc/Alloc-amino acids in high yields by following a conventional procedure. Amongst the Fmoc-oxime derivatives, the N -hydroxypicolinimidoyl cyanide derivative (N -{[(9H-fluoren-9-yl)methoxy]carbonyloxy}picolinimidoyl cyanide) gave the best results for the preparation of Fmoc-Gly-OH, which is the most predisposed to give side reactions. The same Alloc-oxime analogue afforded the preparation of Alloc-Gly-OH in good yield, purity, and extremely low dipeptide formation, as analyzed by reverse-phase HPLC and NMR spectroscopy. [source] Stable Ion and Electrophilic Substitution (Nitration and Bromination) Study of A-Ring Substituted Phenanthrenes: Novel Carbocations and Substituted Derivatives; NMR, X-ray Analysis, and Comparative DNA BindingEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2007Cédric Brulé Abstract Persistent carbocations were generated from five A-ring mono- and di-substituted phenanthrenes [3-OMe; 4-OMe, 1,3-bis(OMe), 2,4-bis(OMe), and 1,3-bis(Me)]. In all cases protonation occurs in the A-ring, ortho/para relative to methoxy or methyl substituent(s). Complete NMR assignments of the resulting carbocations are reported and their charge delocalization modes are discussed. Mild nitration (with 20,50,% aqueous HNO3 at ,10 °C or at room temp.) and bromination (NBS/MeCN/room temp.) of these substrates resulted in the synthesis of several novel mononitro-/dinitro- as well as monobromo/dibromo derivatives, including those with nitro or bromo substituent in the bay-region. Correspondence between the site of attack in low-temperature protonation study and nitro substitution in ambient mild nitrations are examined. Complete NMR assignments for the new derivatives are reported as well as X-ray structures for 2,4-dimethoxy-1-nitro- and 1,3-dimethyl-4-nitrophenanthrenes. A comparative DNA binding study with MCF cells on three of the synthesized mononitro and one dinitro derivative showed that 1,3-dimethyl-9-nitro- (nitro at the meso position), 3-methoxy-4-nitro- (nitro in bay-region), and 1,3-dimethoxy-4,9-dinitrophenanthrenes (nitro in both meso and bay-regions) formed DNA adducts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Chondrochloren A and B, New ,-Amino Styrenes from Chondromyces crocatus (Myxobacteria)EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2003Rolf Jansen Abstract In a screening for biologically active metabolites of the genus Chondromyces, two novel metabolites, chondrochloren A (1) and B (2), were isolated from several strains of C. crocatus. Compounds 1 and 2 are unique chloro-hydroxy-styryl amides of a highly modified C14 carboxylic acid, which comprises an unsaturated ketone, two hydroxy, two methoxy and three methyl groups. After assignment of the absolute configuration of both carbinol stereocenters by Mosher's method, NMR spectroscopic data combined with MM2 calculations allowed the prediction of the preferred conformation in solution. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis, Photophysical, and Electroluminescent Device Properties of Zn(II)-Chelated Complexes Based on Functionalized Benzothiazole DerivativesADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Soo-Gyun Roh Abstract New Zn(II)-chelated complexes based on benzothiazole derivatives, including substituted functional groups such as methyl (MeZn), methoxy (MeOZn), or fluorenyl unit (FuZn), are investigated to produce white-light emission. 2-(2-Hydroxyphenyl)benzothiazole derivatives in toluene and DMSO exhibit excited-state intramolecular proton transfer (ESIPT), leading to a large Stokes shift of the fluorescence emission. However, in methanol they exhibit no ESIPT due to the intermolecular hydrogen bonding between the 2-(2-hydroxyphenyl)benzothiazole derivative and methanol. Their Zn(II)-chelated complexes exhibit the absorption band red-shifted at 500,nm in nonpolar solvent and the absorption band blue-shifted at about 420,nm in protic solvent. In multilayer electroluminescent devices, methyl-substituted Zn(II)-chelated complex (MeZn) exhibits excellent power efficiency and fluorene-substituted Zn(II)-chelated complex (FuZn) has a high luminance efficiency (1,cd,m,2 at 3.5,V, 10,400,cd,m,2 at 14,V). The EL spectra of Zn(II)-chelated complexes based on benzothiazole derivatives exhibit broad emission bands. In addition, their electron-transport property for red,green,blue (RGB) organic light-emitting diodes (OLEDs) is systematically studied, in comparison with that of Alq3. The results demonstrate the promising potential of MeZn as an electron-transporting layer (ETL) material in preference to Alq3, which is widely used as an ETL material. [source] Dramatic Morphology Control in the Fabrication of Porous Polymer Films,ADVANCED FUNCTIONAL MATERIALS, Issue 22 2008Luke A. Connal Abstract Highly ordered, porous honeycomb films are prepared by the breath-figure (BF) technique using dendron-functionalized star polymers as precursors. By changing the nature of the dendritic end groups, dramatically different porous morphologies can be produced. Three series of star polymers are prepared with both the size of the 2,2-bis(methoxy)propionic acid (bis-MPA)-based dendron end group and the dendron functionality being varied. Star polymers end-functionalized with acetonide-protected dendrons (generations 1 to 4) are initially prepared and the acetonide groups subsequently deprotected to yield hydroxyl-functionalized star polymers. Modification of these hydroxyl groups with pentadecafluorooctanoyl chloride yields a third series of functionalized star polymers. The resulting star polymers have surface groups with very different polarity and by utilizing these star polymers to form honeycomb films by the BF technique, the morphology produced is dramatically different. The star polymers with amphiphilic character afford interconnected porous morphologies with multiple layers of pores. The star polymers with pentadecafluorooctanoyl end groups show highly ordered monolayers of pores with extremely thin walls and represent a new porous morphology that has previously not been reported. The ability to prepare libraries of different dendronized star polymers has given further insights into the BF technique and allows the final porous morphology to be controllably tuned utilizing the functional chain ends and generation number of the dendronized star polymers. [source] New Monofunctionalized Fluorescein Derivatives for the Efficient High-Throughput Screening of Lipases and Esterases in Aqueous MediaHELVETICA CHIMICA ACTA, Issue 3 2006Yongzheng Yang Abstract Monoalkylation or acylation of fluorescein (1) with various acyloxymethyl or acyl halides afforded, respectively, a series of ether- (2) and ester-functionalized (3) fluorogenic probes. The highly reactive and water-soluble substrates release fluorescein (1) upon reaction with lipases and esterases within seconds or minutes, both under fully aqueous conditions or in the presence of DMSO (20%) as a co-solvent. The most-reactive substrates in the two series were the octanoic acid derivatives 2f (=,2-{6-[(octanoyloxy)methoxy]-3-oxo-3H -xanthen-9-yl}benzoic acid) and 3a (=,2-[6-(octanoyloxy)-3-oxo-3H -xanthen-9-yl]benzoic acid). Esterases were found to generally react faster under aqueous conditions, while lipases were more reactive in the presence of DMSO as a co-solvent. [source] Crystal and molecular structures of atropisomeric N -aryl-1,2,3,4-tetrahydro-3,3-dimethyl-2,4-quinolinedionesHETEROATOM CHEMISTRY, Issue 3 2008Mario Cetina The crystal structures of N -aryl-1,2,3,4-tetrahydro-3,3-dimethyl-2,4-quinolinediones bearing methoxy- (1), methyl- (2), and chloro- (3) substituents in 2,-position of the phenyl ring have been determined by X-ray crystal structure analysis. The heterocyclic ring in 1,3 adopts an envelope conformation, with the smallest ring puckering in the ortho-chloro derivative 3. The N -aryl ring is almost perpendicular with respect to the quinoline-2,4-dione ring. The corresponding dihedral angle values are 83.2(1)°, 80.0(9)°, and 83.4(2)° in 1, 2 and 3, respectively. The hydrogen bond of CH,,,O type joins the molecules of the ortho-methoxy derivative 1 into dimers. The supramolecular structure also contains two CH,,,, interactions that link the hydrogen-bonded dimers into sheets. In ortho-methyl derivative 2, one CH,,,, interaction generates infinite chains, whereas two CH,,,O hydrogen bonds and three CH,,,, interactions in the ortho-chloro derivative 3 form three-dimensional framework. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:325,331, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20436 [source] Iron-Catalyzed Oxidative Mono- and Bis-Phosphonation of N,N -DialkylanilinesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Wei Han Abstract The dehydrogenative ,-phosphonation of substituted N,N -dialkylanilines by dialkyl H -phosphonates was achieved under mild conditions by using environmentally benign iron(II) chloride as catalyst and tert -butyl hydroperoxide as oxidant. The reaction proceeded in the presence of electron-donating (methoxy, methyl, benzyl) and electron-withdrawing ring-substitutents (bromo, carbonyl, carboxyl, m -nitro) in moderate to good yields. The X-ray crystal structure of N -(5,5-dimethyl-2-oxo-2,5 -[1,3,2]dioxaphosphinan-2-yl-methyl)- N -methyl- p -toluidine was determined. Bis-(4-(dimethylamino)phenyl)methane and bis-4,4,-(dimethylamino)benzophenone underwent bisphosphonation selectively by respective monophosphonation at the remote dimethylamino groups. Furthermore, the use of excess dialkyl H -phosphonate and oxidant allowed us to functionalize both methyl groups of N(CH3)2 in N,N -dimethyl- p -toluidine and N,N -dimethylaminomesidine, respectively, to obtain ,,,,-bisphosphonatoamines in high yield. [source] Various ,-Oxygen Functionalizations of ,-Dicarbonyl Compounds Mediated by the Hypervalent Iodine(III) Reagent p -Iodotoluene Difluoride with Different Oxygen-Containing NucleophilesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 2-3 2010Jun Yu Abstract p -Iodotoluene difluoride (p -Tol-IF2) has been found to be a general reagent for the effective introduction of various oxygen-containing functionalities including tosyloxy, mesyloxy, acetoxy, phosphoryloxy, methoxy, ethoxy and isopropoxy at the ,-position of ,-dicarbonyl compounds. These transformations can be readily realized by the use of the combined reagent of p -iodotoluene difluoride and various oxygen-containing nucleophilic compounds such as p -toluenesulfonic acid, methanesulfonic acid, acetic acid, diphenyl phosphate, methanol, ethanol and propan-2-ol under mild conditions, respectively. And, the in situ generated hypervalent iodine(III) species via ligand exchange between p -iodotoluene difluoride and the respective oxygen-containing nucleophiles are believed to be the real oxidizing agents in such transformations. [source] Regioselective C-2 or C-5 Direct Arylation of Pyrroles with Aryl Bromides using a Ligand-Free Palladium CatalystADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2009Julien Roger Abstract A simple and atom-economical procedure for the regioselective C-2 or C-5 arylation of pyrroles via a CH bond activation is reported. Only 0.5,0.01 mol% of commercially available and air-stable ligand-free palladium(II) acetate [Pd(OAc)2] was employed as the catalyst. The presence of electron-withdrawing substituents such as formyl, acetyl or ester at the C-2 position of the pyrrole is tolerated. This environmentally attractive procedure has also been found to be tolerant to a very wide variety of functional groups on the aryl bromides such as formyl, acetyl, propionyl, ester, nitrile, nitro, fluoro, methoxy, amino or trifluoromethyl. [source] Reaction mechanism of methanol decomposition on Pt-based model catalysts: A theoretical studyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 10 2010Cui-Yu Niu Abstract The decomposition mechanisms of methanol on five different Pt surfaces, the flat surface of Pt(111), Pt-defect, Pt-step, Pt(110)(1 × 1), and Pt(110)(2 × 1), have been studied with the DFT-GGA method using the repeated slab model. The adsorption energies under the most stable configuration of the possible species and the activation energy barriers of the possible elementary reactions involved are obtained in this work. Through systematic calculations for the reaction mechanism of methanol decomposition on these surfaces, we found that such a reaction shows the same reaction mechanism on these Pt-based model catalysts, that is, the final products are all H (Hads) and CO (COads) via OH bond breaking in methanol and CH bond scission in methoxy. These results are in general agreement with the previous experimental observations. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010. [source] New derivatives of dibenzo[b,e][1,4]diazepin-1-ones by an efficient synthesis and spectroscopyJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2007Eduardo Cortés Cortés An efficient synthesis of four steps to obtain twelve new derivatives of 3,3-dimethyl-2,3,4,5,10,11-hexahydro-8-[(o -; and p -methoxy)phenoxy]-11-[(o -; and p -R)phenyl]-1H -dibenzo[b,e][1,4]diazepin-1-ones IV, 1-12 with possible biological and pharmacological activity as anticonvulsant and schizophrenia treatment in the central nervous system (CNS). The final products were obtained by condensation and cyclization between 3-{4-[(o -; and p -methoxy)phenoxy]-1,2-phenylenediamine}-5,5-dimethyl-2-cyclohexenone with (o -; and p -R)benzaldehyde. The structure of all products was corroborated by spectroscopy of ir, 1H-nmr, 13C-nmr, with bidimensional experiments and MS in Low and high resolution with Collision-Induced Dissociation experiments (CID). [source] Syntheses and photophysical properties of some 4-arylpyridinium saltsJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2001Charles J. Kelley A number of 4-arylpyridines, many methoxy substituted, were prepared by an efficient two-step method involving aryl Grignard addition to 1-methyl-4-piperidone and direct aromatization of the resulting 4-aryl-4-piperidinols. The pyridines were N -alkylated to give sulfonate salts desired for their fluorescent properties. Study of selected compounds as laser dyes revealed several structures to be efficient dyes lasing in the 530-550 nm range. Two new diazaquaterphenyls were prepared and were quaternized. These salts exhibited intense fluorescence in the 420-450 nm range, but would not lase. A phenolic azaterphenyl suitably substituted for excited state intramolecular proton transfer (ESIPT) did not fluoresce at all. [source] Synthesis of deuterium-labelled (,)-galanthamineJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2008Julien Rouleau Abstract The synthesis of deuterium-labelled galanthamine is reported. 6-[2H3]methoxy- N -[2H3]methyl-(,)-galanthamine was obtained in seven steps from galanthamine. The synthesis was carried out by selective O - and N -demethylations. The [2H3]- N -methyl and [2H3]- O -methyl-groups were introduced by selective aminoreduction and O -methylation. Copyright © 2008 John Wiley & Sons, Ltd. [source] Radiosynthesis of (±)-(2-((4-(2-[18F]fluoro-ethoxy)phenyl)bis(4-methoxy-phenyl)methoxy)ethylpiperidine-3-carboxylic acid: a potential GAT-3 PET ligand to study GABAergic neuro-transmission in vivoJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 9 2001Ralf Schirrmacher Abstract A dysfunction of GABAergic neurotransmission is related to diseases such as epilepsy, Huntington-disease and Parkinson-syndrome. A new 18F-fluorine labelled GABA transporter ligand for the GABA-transporter subtype GAT-3 was developed which may allow the in vivo visualisation of GABAergic neurotransmission. The precursors ethyl (2-(4-hydroxyphenyl)bis(4-methoxyphenyl)-methoxy)ethyl)-piperidine-3-carboxylate and ethyl(2-((4-(2-tosylethoxy)phenyl)-bis(4-methoxyphenyl)-methoxy) ethyl)-piperidine3-carboxylate were synthesised and labelled by the use of 2-[18F]fluoroethyltosylate or [18F]fluoride. Subsequent cleavage of the ester moiety gave the final product (±)-(2-((4-(2-[18F]fluoroethoxy)phenyl)bis(4-methoxy-phenyl)methoxy)ethyl)piperidine-3-carboxylic acid in a decay corrected yield of 33,36%. Preliminary biodistribution kinetics were determined with BALB/c mice ex vivo for brain, liver, kidney, spleen, blood and bone. (2-((4-(2-[18F]fluoroethoxy)-phenyl)bis(4-methoxyphenyl)methoxy)-ethyl) piperidine-3-carboxylic acid showed a maximum brain uptake after 1 h p.i. of about 0.3% ID/g. Copyright © 2001 John Wiley & Sons, Ltd. [source] Implication of Rho-associated kinase in the elevation of extracellular dopamine levels and its related behaviors induced by methamphetamine in ratsJOURNAL OF NEUROCHEMISTRY, Issue 2 2003Minoru Narita Abstract A growing body of evidence suggests that several protein kinases are involved in the expression of pharmacological actions induced by a psychostimulant methamphetamine. The present study was designed to investigate the role of the Rho/Rho-associated kinase (ROCK)-dependent pathway in the expression of the increase in extracellular levels of dopamine in the nucleus accumbens and its related behaviors induced by methamphetamine in rats. Methamphetamine (1 mg/kg, subcutaneously) produced a substantial increase in extracellular levels of dopamine in the nucleus accumbens, with a progressive augmentation of dopamine-related behaviors including rearing and sniffing. Methamphetamine also induced the decrease in levels of its major metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanilic acid (HVA). Both the increase in extracellular levels of dopamine and the induction of dopamine-related behaviors by methamphetamine were significantly suppressed by pretreatment with an intranucleus accumbens injection of a selective ROCK inhibitor Y-27632. In contrast, Y-27632 had no effect on the decrease in levels of DOPAC and HVA induced by methamphetamine. Under these conditions, there were no changes in protein levels of membrane-bound RhoA in the nucleus accumbens following methamphetamine treatment. It is of interest to note that the microinjection of Y-27632 into the nucleus accumbens failed to suppress the increases in extracellular levels of dopamine, DOPAC, and HVA in the nucleus accumbens induced by subcutaneous injection of a prototype of µ-opioid receptor agonist morphine (10 mg/kg). Furthermore, perfusion of a selective blocker of voltage-dependent Na+ channels, tetrodotoxin (TTx) into the rat nucleus accumbens did not affect the increase in extracellular levels of dopamine in the rat nucleus accumbens by methamphetamine, whereas the morphine-induced dopamine elevation was eliminated by this application of TTx. The extracellular level of dopamine in the nucleus accumbens was also increased by perfusion of a selective dopamine re-uptake inhibitor 1-[2-[bis(4-fluorophenyl)methoxy]-4-(3-phenylpropyl)piperazine (GBR-12909) in the nucleus accumbens. This effect was not affected by pretreatment with intranucleus accumbens injection of Y-27632. These findings provide first evidence that Rho/ROCK pathway in the nucleus accumbens may contribute to the increase in extracellular levels of dopamine in the nucleus accumbens evoked by a single subcutaneous injection of methamphetamine. In contrast, this pathway is not essential for the increased level of dopamine in this region induced by morphine, providing further evidence for the different mechanisms of dopamine release by methamphetamine and morphine in rats. [source] Post-synthesis incorporation of a lipidic side chain into a peptide on solid supportJOURNAL OF PEPTIDE SCIENCE, Issue 11 2002Céline Douat Abstract A new strategy for the synthesis of lipopeptides has been developed. Using Weinreb (N -methoxy, N -methyl) amide as an aldehyde function precursor on the side chains of Asp or Glu residues, this new strategy avoids the synthesis of a lipidic amino acid residue before its incorporation in the peptide sequence. The aldehyde generated on the solid support can react with ylides leading to unsaturated or saturated side chains or with various nucleophiles to yield non-coded amino acid residues incorporated into the sequence. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] Stability studies of oxazolidine-based compounds using 1H NMR spectroscopyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2010Gerard P. Moloney Abstract A series of oxazolidine-based compounds with a variety of substituents in positions 2 and 3 was synthesized and their stability studied. Ring opened intermediates formed on addition of limiting amounts of D2O to oxazolidine solutions, as observed by NMR. As the hydrolysis reactions proceeded, a series of novel dimeric ,-amino alcohol compounds formed via an internal reaction between ephedrine and the ring opened intermediates. 2-Phenyl substituted oxazolidine compounds containing electron withdrawing nitro substituents were more rapidly hydrolyzed than the unsubstituted derivative and methoxy substituted compounds, with the nitro substituents appearing to stabilize the ring opened intermediates. Two oxazolidine derivatives, with a methyl and proton at position 2, were found to be more stable to oxazolidine hydrolysis than the 2-phenyl substituted compounds. Oxazolidines incorporating phenyl substituents at position 3 were synthesized and found to be less stable than those incorporating a methyl substituent at position 3. These fundamental structure,activity relationships may be useful when choosing oxazolidine derivatives as synthetic intermediates and as prodrugs for the delivery of compounds containing either ,-amino alcohol or aldehyde components. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3362,3371, 2010 [source] Biodegradable polymers based on renewable resources.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005Abstract Novel polycarbonates, with pendant functional groups, based on 1,4:3,6-dianhydrohexitols and L -tartaric acid derivatives were synthesized. Solution polycondensations of 1,4:3,6-dianhydro-bis- O -(p -nitrophenoxycarbonyl)hexitols and 2,3-di- O -methyl- L -threitol or 2,3- O -isopropylidene- L -threitol afforded polycarbonates having pendant methoxy or isopropylidene groups, respectively, with number average molecular weight (Mn) values up to 3.61 × 104. Subsequent acid-catalyzed deprotection of isopropylidene groups gave well-defined polycarbonates having pendant hydroxyl groups regularly distributed along the polymer chain. Differential scanning calorimetry (DSC) demonstrated that all the polycarbonates were amorphous with glass transition temperatures ranging from 57 to 98 °C. Degradability of the polycarbonates was assessed by hydrolysis test in phosphate buffer solution at 37 °C and by biochemical oxygen demand (BOD) measurements in an activated sludge at 25 °C. In both tests, the polycarbonates with pendant hydroxyl groups were degraded much faster than the polycarbonates with pendant methoxy and isopropylidene groups. It is noteworthy that degradation of the polycarbonates with pendant hydroxyl groups was remarkably fast. They were completely degraded within only 150 min in a phosphate buffer solution and their BOD-biodegradability reached nearly 70% in an activated sludge after 28 days. The degradation behavior of the polycarbonates is discussed in terms of their chemical and physical properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3909,3919, 2005 [source] Synthesis of polyesters by the polyaddition of bis(oxetane)s with active di(ester)sJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2004Hiroto Kudo Abstract The polyaddition of bis(oxetane)s 1,4-bis[(3-ethyl-3-oxetanylmethoxymethyl)]benzene (BEOB), 4,4,-bis[(3-ethyl-3-oxetanyl)methoxy]benzene (4,4,-BEOBP), 1,4-bis[(3-ethy-3-oxetanyl)methoxy] -benzene (1,4-BEOMB), 1,2-bis[(3-ethyl-3-oxetanyl)methoxy]benzene (1,2-BEOMB), 4,4-bis[(3-ethyl-3-oxetanyl)methoxy]biphenyl (4,4,-BEOMB), 3,3,,5,5,-tetramethyl-[4,4,-bis(3-ethyl-3-oxetanyl)methoxy]biphenyl (TM-BEOBP) with active diesters di- s -phenylthioterephthalate (PTTP), di- s -phenylthioisoterephthalate (PTIP), 4,4,-di(p -nitrophenyl)terephthalate (NPTP), 4,4,-di(p -nitrophenyl)isoterephthalate (NPIP) were carried out in the presence of tetraphenylphosphonium chloride (TPPC) as a catalyst in NMP for 24 h, affording corresponding polyesters with Mn's in the range 2200,18,200 in 41,98% yields. The obtained polymers would soluble in common organic solvents and had high thermal stabilities. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1528,1536, 2004 [source] Atom Transfer Radical Polymerization and Third-Order Nonlinear Optical Properties of New Azobenzene-Containing Side-Chain PolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2007Najun Li Abstract The atom transfer radical polymerization (ATRP) technique has been successfully applied to synthesize a series of nonlinear optically (NLO) active homopolymers, 4-(4-nitrophenyl-diazenyl) phenyl acrylate (P - NPAPA) and 4-(4-methoxyphenyl-diazenyl) phenyl acrylate (P - MPAPA), containing azobenzene groups on the side chain. The third-order NLO properties of the polymer films were measured by the degenerated four-wave mixing (DFWM) technique. A dependence of the ,(3) values and response times of polymers on their number-average molecular weight and the electronic effect of the substituent (nitro- or methoxy-) on the azobenzene group have been evidenced. The increasing ,(3) value of the polymer films at the magnitude of about 10,10 was displayed with increasing molecular weight and the presence of the push-pull electronic system contributes much in enhancing the third-order NLO susceptibility of polymers. [source] | ||||||||||||||||||||||||||||||||||