bluuebunny/crossref_metadata_2025 huggingface dataset:
DISQUAC characterization of the carbonyl–oxygen interactions in binary liquid organic mixtures containing linear molecules: ketones and a monoether, diether, or triether
Authors: González J.A. , Martínez J.M. Fernández , Fuente I. García de la , Cobos J.C.
Published: May 2006

The available data in the literature on vapour–liquid equilibria, excess Gibbs energies, and excess enthalpies for linear ketones + linear mono- or poly-ether mixtures are examined in terms of the DISQUAC group contribution model. Interaction parameters are reported. The quasichemical interchange coefficients are independent of the compounds in the systems; the dispersive interchange coefficients depend on the intramolecular environment of the carbonyl and (or) oxygen groups. Proximity effects, which seem to lead to an important increase of the interaction parameters, are briefly considered in treating systems including 1-methoxy-2-propanone or dimethyl carbonate molecules. DISQUAC consistently describes the experimental data of the mixtures investigated. The rather good representation obtained for vapour–liquid equilibria at high temperatures is noteworthy. A discussion in terms of effective and reduced dipole moments of binary mixtures containing carbonyl and oxygen groups in the same or different molecules is also presented. Key words: liquids, mixtures, thermodynamics, dipole moments, group contributions.
Synthesis of dimethylplatinum(IV) compounds, [{PtMe2X2}n], [{PtMe2XY}n], and, in solution,fac-[PtMe2X(H2O)3]+, where X and Y are anionic ligands
Authors: Appleton Trevor G. , D'Alton Campbell J. , Hall John R. , Mathieson Michael T. , Williams Mark A.
Published: May 2006

Oxidative addition of X2(X = Cl, Br, I) to cis-[PtMe2L2] (L = pyridine, py, or L2 = N,N,N′,N′-tetramethylethylenediamine (tmen) gave [PtMe2X2L2]. For X = Br, I, treatment with aqueous HClO4gave insoluble [{PtMe2X2}n], but for X = Cl, [PtMe2Cl2(H2O)2] remained in solution, with [{PtMe2Cl2}n] depositing only from concentrated solution. [PtMe2L2] (L = py, 1/2(tmen)) with water gave [PtMe2(OH)2L2], which, on treatment with HClO4gave cis-[PtMe2(H2O)4](ClO4)2in solution. Water also reacted with [PtMe2(nbd)] (nbd = norbornadiene) to give [{PtMe2](OH)2}n]•mH2O. Alcohols ROH (R = Me, Et) with cis-[PtMe2py2] gave [PtMe2(OR)(OH)py2], which reacted with aqueous HClO4solution to give fac-[PtMe2(OR)(H2O)3]ClO4in solution. Addition of chloride to this solution caused precipitation of [{PtMe2(OR)Cl}n]. Reaction of [{PtMe2XY}n] with AgNO3in water gave fac-[PtMe2X(H2O)3](NO3) in solution (X = Y = Cl, Br, I or Y = Cl, X = OR); for X = I added acid was necessary to prevent precipitation of [{PtMe2I(OH)}n]. Reaction of a solution of fac-[PtMe2Br(H2O)3](NO3) with AgNO2gave fac-[PtMe2(NO2)(H2O)3](NO3) in solution, but an analogous reaction with AgSCN gave a complex in solution formulated as fac-[PtMe2(SCN)(H2O)3](NO3) only in low yield. Key words: platinum, methyl, pyridine, aqua, alkoxide, oxidative addition, NMR.
Alkylaluminum complexes containing pyridyl amido ligands. Syntheses and characterization of AlMe2[N(CH2-2-Py)2], Al2Me5[N(CH2-2-Py)2], and Al2Me4[2,3,5,6-tetra(2-pyridyl)piperazyl], an unusual carbon–carbon bond coupling product
Authors: Trepanier Steven J. , Wang Suning
Published: May 2006

The reactions of AlMe3 with di(2-pyridylmethyl)amine have been investigated. Two new complexes, AlMe2[N(CH2-2-Py)2] (1) and Al2Me4[2,3,5,6-tetra(2-pyridyl)piperazyl] (3), were obtained as the major and the minor product, respectively, from the reaction of AlMe3 with di(2-pyridylmethyl)amine in a 1:1 ratio in toluene at 23 °C. The reaction of AlMe3 with di(2-pyridylmethyl)amine in a 2:1 ratio yielded a dinuclear complex Al2Me5[N(CH2-2-Py)2] (2). These complexes were fully characterized by NMR, and elemental and single-crystal X-ray diffraction analyses. Crystal data: 1, C14H18N3Al, monoclinic, P21/m, a = 7.568(2), b = 7.340(1), c = 13.120(8) Å, β = 104.17(3)°, V = 706.6(4) Å3, Z = 2; 2, C14H27N3Al2, triclinic, [Formula: see text], a = 8.422(1), b = 16.711(6), c = 7.659(1) Å, α = 91.94(2)°, β = 113.08(1)°, γ = 85.17(2)°, V = 988.2(4) Å3, Z = 2; 3, C28H32N6Al2, monoclinic, P21/c, a = 7.522(8), b = 15.841(8), c = 11.584(4) Å, β = 98.53(5)°, V = 1365(1) Å3, Z = 2. Compound 1 is a mononuclear complex with the aluminum atom in an approximately trigonal bipyramidal geometry and the amido nitrogen atom in a trigonal planar geometry. Compound 2 contains two aluminum centers bridged by an amido nitrogen atom where one of the aluminum atoms has a tetrahedral geometry while the other has a trigonal bipyramidal geometry. The dinuclear compound 3 can be described as the result of two unusual C—C bonds coupling between the methylene carbon atoms of two molecules of 1. The aluminum coordination environment in 3 is similar to that of 1. Key words: aluminum, amide, pyridyl, 2,3,5,6-tetra(2-pyridyl)piperazine, structure.
Synthesis, characterization, and reactivity of a ruthenium(II)N,N′,N″-tris(2-pyridyl)phosphine complex. X-ray analysis of RuCl2(PPh3)(Ppy3) (py = 2-pyridyl)
Authors: Schutte Richard P. , Rettig Steven J. , James Brian R.
Published: May 2006

Reaction of RuCl2(PPh3)3with Ppy3(py = 2-pyridyl) in benzene produced the N,N′,N″-Ppy3complex RuCl2(PPh3)(Ppy3) 1. Crystals of RuCl2(PPh3)(Ppy3)•2CH2Cl2(C35H31Cl6N3P2Ru) are monoclinic, a = 17.269(2), b = 10.797(1), c = 20.604(1) Å, β = 107.461(6)°, Z = 4, space group P21/c. The structure was solved by the Patterson method and was refined by full-matrix least-squares procedures to R = 0.039 and Rw = 0.035 for 4184 reflections with I ≥ 3σ(I). Complex 1 reacts in MeOH or benzene with two-electron donors (L) to give the chloride-substituted, [RuCl(L)(PPh3)(Ppy3)]PF6, or the triphenylphosphine-substituted products, RuCl2(L)(Ppy3), (L = CO, MeCN, PhCN), respectively. [RuCl(MeOH)(PPh3)(Ppy3)]BPh4was also isolated. The non-coordinated phosphorus atom in 1 was oxidized to form RuCl2(PPh3)(OPpy3). Key words: ruthenium, pyridylphosphines, crystal structure
Preparation and structure of 2-chloro-1,3-dimethyldiaza-2-arsenane, 1,3-dimethyldiaza-2-arsenanium tetrachlorogallate, and butadiene cycloadducts of diazarsenium cations
Authors: Burford Neil , Macdonald Charles L.B. , Parks Trenton M. , Wu Gang , Borecka Borzena , Kwiatkowski Witold , Cameron T. Stanley
Published: May 2006

1,3-Dimethyldiaza-2-arsenanium tetrachlorogallate (crystal data: C5H12AsCl4GaN2, M = 386.61, orthorhombic, space group Pca21, a = 14.432(3) Å, b = 6.7580(14) Å, c = 13.905(3) Å, V = 1356.2(5) Å3) is synthesized by the routine chloride ion abstraction procedure from 2-chloro-1,3-dimethyldiaza-2-arsenane (crystal data: C5H12AsClN2, M = 210.54, monoclinic, space group P21/n, a = 7.206(1) Å, b = 9.650(1) Å, c = 13.021(2) Å, β = 99.61(2)°, V = 892.8(2) Å3). X-ray crystallographic studies of both compounds are described together with that for 2-chloro-1,3-dimethyldiaza-2-arsolidine (crystal data: C4H10AsClN2, M = 196.51, monoclinic, space group P21/n, a = 6.959(7) Å, b = 9.23(2) Å, c = 12.14(2) Å, β = 95.4(1)°, V = 777(4) Å3) providing useful structural comparisons. In contrast to the closely related arsolidinium salts, the diazarsenanium gallate exhibits a monomeric solid state structure. Rapid and quantitative cycloaddition reactions of the diazarsolidinium and diazarsenanium cations with 2,4-dimethylbutadiene give similar cycloadducts. The Diels–Alder type arsolidinium adduct is structurally characterized (crystal data: C10H20AsCl4GaN2, M = 454.73, orthorhombic, space group Pca21, a = 18.471(2) Å, b = 7.000(2) Å, c = 13.738(1) Å, V = 1776.2(8) Å3), and the related structure of the arsenanium cycloadduct is confirmed by 2D NMR. Key words: arsenium, cycloadditions, arsenanium, Diels–Alder, cyclochloroarsines.
An unusually large value of1J(31P,31P) for a solid triphenylphosphine phosphadiazonium cationic complex: determination of the sign ofJfrom 2D spin-echo experiments
Authors: Eichele Klaus , Wasylishen Roderick E. , Schurko Robert W. , Burford Neil , Whitla W. Alex
Published: May 2006

Phosphorus-31 NMR spectra of a solid triphenylphosphine phosphadiazonium salt, [Mes*NP-PPh3][SO3CF3], have been acquired at 4.7 and 9.4 T. Analysis of the spectra obtained with magic-angle spinning indicates that the two phosphorus nuclei are strongly spin–spin coupled, [Formula: see text], despite the unusually long P—P separation, rP,P = 2.625 Å. Two-dimensional spin-echo spectra provide convincing evidence that1J(31P,31P) is negative. Semi-empirical molecular orbital calculations at the INDO level support the negative sign for1J(31P,31P). A large span, 576 ppm, is observed for the chemical shift tensor of the two-coordinate phosphorus centre (δ11 = 307 ppm, δ22 = 174 ppm, δ33 = −269 ppm), which is very similar to the value previously reported for the non-coordinated phosphorus centre in the free Lewis acid, [Mes*NP][AlCl4]. The principal components and orientations of the phosphorus shielding tensors of these compounds are compared with those calculated for [HNP]+and its phosphine adduct using the ab initio Gauge-Including Atomic Orbitals method. The phosphorus chemical shift tensor of the triphenylphosphine moiety has a relatively small span of 33 ppm. Key words: spin–spin coupling constants, solid-state NMR,31P NMR, MO calculations, phosphadiazonium cation, P—P bonds.
Synthesis and characterization of phosphinimine-substituted trifluoro- or trichloro-p-benzoquinones and their cationic Rh(I) complexes. The crystal and molecular structure of 3,5,6-trichloro-2-(triphenylphosphinimino)-p-benzoquinone
Authors: Li Jin , Katti Kattesh V. , Cavell Ronald G. , Pinkerton A. Alan , Nar Herbert
Published: May 2006

Reaction of tetrafluoro- or tetrachloro-p-benzoquinone with silylated phosphoranimines R2R′P=NSiMe3 (R = Ph, Me) yields very highly colored monosubstituted derivatives of the p-quinone that act as two-electron acceptors showing clean, reversible CV traces. The molar absorptivity values are typical of dyes. These ligands also form chelate complexes with Rh(I) precursors using the quinone oxygen and the imine nitrogen donor sites. One of the quinone derivatives, 3,5,6-trichloro-2-(triphenylphosphinimino)-p-benzoquinone, has been structurally characterized. The iminated quinone shows a normal P=N bond length (1.597(2) Å) and P-N-C angle (P-N-C(3) 132.7(2)°). The N—C(3) bond, 1.327(3) Å, is a little shorter as is expected for the establishment of a conjugated structure between the phosphinimine substituent and the quinone ring. Some steric crowding pushes the Cl and N substituents on the quinone ring out of the plane of the ring. Key words: quinones, phosphinimines, fluorine, chlorine, rhodium.
Characterization of humic substances extracted from Canadian lake sediments
Authors: Belzile Nelson , Joly Helen A. , Li Hongbo
Published: May 2006

Humic substances (HS) were extracted from the sediments of four Sudbury area lakes, namely, Tilton, Clearwater, Silver, and Ramsey Lakes, with the aid of 0.1 M Na4P2O7 and 0.5 M NaOH solutions. The HS (humic and fulvic acids) were purified and characterized using the methods of elemental analysis, visible spectroscopy (E4/E6 ratio), FTIR, and solid-state 13C CPMAS NMR. A substantial amount of information with regard to the composition and chemical nature of lake sediment HS was obtained. The results obtained for the Sudbury area lake sediments were compared with one another and with HS from other sources, such as soils. The elemental composition, atomic ratios, E4/E6 ratios, and FTIR and NMR features of the samples from the above lakes were found to be nearly identical, suggesting that HS formed in the Sudbury area have similar chemical properties. Compared with soil HS, the Sudbury lake sediments HS have undergone a low degree of aromatic condensation and are considerably more aliphatic in nature. Keywords: humic substances, characterization, lake sediments, extraction, 13C NMR.
FTIR spectroscopic investigation of matrix-isolated isomerization and decomposition products of ionized acetone: generation and characterization of 1-propen-2-ol
Authors: Zhang Xiaokui K. , Parnis J. Mark , Lewars Errol G. , March Raymond E.
Published: May 2006

An electron bombardment – matrix isolation apparatus was used to generate and isolate products from acetone isomerization and decomposition for infrared spectroscopic examination. Bombardment of a dilute acetone/argon gas mixture (1:400) above a 12 K matrix isolation substrate leads to the direct observation of neutral fragmentation and isomerization products. A major product is 1-propen-2-ol, the enolic tautomer of acetone, whose IR absorption spectrum, and that of its perdeutero analog, are interpreted with the aid of ab initio computations. The observation of matrix-isolated decomposition products of acetone such as acetyl radicals, ketene, methane, and CH3• is interpreted in terms of ion and neutral decomposition processes occurring in the gas phase above the matrix surface and during matrix condensation. The detection of matrix-isolated 1-propen-2-ol is consistent with a process involving acetone ionization, isomerization, neutralization, and stabilization, an approach that may have general utility in the generation of other thermodynamically unfavourable neutral isomers of organic molecules. Keywords: enol, isomerization, acetone, infrared, ionization, 1-propen-2-ol.
Comparison of crystal and solution structures and 1H and 13C chemical shifts for grandiflorenic acid, kaurenoic acid, and monoginoic acid
Authors: Enriquez Raul G. , Barajas Julie , Ortiz Benjamin , Lough Alan J. , Reynolds William F. , Yu Margaret , Leon Ismael , Gnecco Dino
Published: May 2006

The crystal structure of monoginoic acid, 3, is determined and compared with previously reported structures of kauradienoic acid, 1, and kaurenoic acid, 2. 1H and 13C chemical shifts are assigned for all three diterpenes and solution and crystal structure conformations are confirmed with the aid of solution NOE measurements. The overall shapes of 2 and 3 are very similar while 1 is significantly dissimilar. These differences may be partially responsible for the reported greater in vitro uterotropic activity of 1, relative to 2 and 3. Keywords: monoginoic acid, kaurodienoic acid, kaurenoic acid.
Metal hydride mediated reduction of 1,3-dimethyl-3(methylthio)oxindole
Authors: Connolly Terrence J. , Durst Tony
Published: May 2006

The metal hydride mediated reduction of 4-carboethoxy-1,3-dimethyl-3-(methylthio)oxindole with lithium aluminum hydride and lithium triethylborohydride was studied. The results show that reduction of the oxindole carbonyl group is competitive with reduction of the pendant ester. The hemi-aminal that results from initial addition of hydride to the oxindole carbonyl may follow a number of reaction pathways, one of which is an unprecedented rearrangement. A mechanism is proposed that accounts for all observed products. Keywords: oxindole, reduction, rearrangement.
Copper(I) chloride-mediated oxidative coupling of alkenyltrialkylstannyl functions: efficient stereocontrolled syntheses of uniquely functionalized conjugated diene systems
Authors: Piers Edward , McEachern Ernest J. , Romero Miguel A. , Gladstone Patricia L.
Published: May 2006

Treatment of the β-trialkylstannyl α,β-unsaturated esters 1–9 with 2.5 equivalents of copper(I) chloride in N,N-dimethylformamide at room temperature results in the efficient, stereocontrolled production of the highly functionalized conjugated dienes 10–18, respectively. In each of these oxidative couplings, production of 1 equivalent of product is accompanied by the formation of 2 equivalents of both the trialkylstannyl chloride and copper metal. Keywords: alkenyltrialkylstannanes, copper(I) chloride, transmetalation, conjugated dienes, oxidative coupling, β-trialkylstannyl α,β-unsaturated esters, substituted dialkyl muconates, organostannane, organocopper.
On a new synthesis of sterpurene and the bioactivity of some related Chondrostereumpurpureum sesquiterpene metabolites
Authors: Strunz George M. , Bethell Richard , Dumas Michael T. , Boyonoski Nick
Published: May 2006

Sterpurene, a sesquiterpene hydrocarbon metabolite of Chondrostereumpurpureum, a plant pathogen and potential mycoherbicide, was synthesized by a six-step sequence, in 33% overall yield. The key steps were a thermal [4 + 2] (Diels–Alder) cycloaddition of a ketene acetal diene with a conjugated ester dienophile, and a remarkably stereoselective [2 + 2] photocycloaddition of ethylene with the resulting conjugated ketone. Several related, more highly oxygenated, metabolites isolated from culture filtrates of C. purpureum (cf. Ayer) were tested for toxicity to cells of a hybrid aspen, Populusdeltoides X nigra. Their phytotoxicity, at concentrations as low as 10 ppm, suggests that, like the endo-polygalacturonase produced by the fungus, these sesquiterpenes may be partially responsible for the foliar lesions associated with infection of deciduous species by the pathogen. Keywords: Chondrostereumpurpureum, mycoherbicide, metabolites, sterpurenes, synthesis, Diels–Alder, photocycloaddition, pyramidalization, phytotoxicity.
New antifungal metabolites from the coprophilous fungus Cercophorasordarioides
Authors: Whyte Authrine C. , Gloer Katherine B. , Gloer James B. , Koster Brenda , Malloch David
Published: May 2006

A chemical investigation of the coprophilous fungus Cercophorasordarioides has led to the isolation of arthrinone (1), a known fungal metabolite, and three new related compounds: 1-dehydroxyarthrinone (2), 3a,9a-deoxy-3a-hydroxy-1-dehydroxyarthrinone (3), and cerdarin (4). These metabolites were obtained from antifungal ethyl acetate extracts of liquid cultures of C. sordarioides through bioassay-guided fractionation, and their structures were assigned on the basis of 1D-NMR, HMQC, and HMBC results. Compounds 2 and 4 exhibited anti-Candida activity. Key words: antifungal, fungal metabolite, natural product, Cercophorasordarioides.
Preparation, biotransformation, and antifungal activity of methyl benzyldithiocarbamates
Authors: Pedras M. Soledade C. , Khan Abdul Q. , Smith Kevin C. , Stettner Shawndra L.
Published: May 2006

The biotransformation of three methyl benzyldithiocarbamates by the blackleg fungus (Leptosphaeriamaculans (Desm.) Ces. et de Not., asexual stage Phomalingam (Tode ex Fr.) Desm) was investigated. The main biotransformation products were isolated and their chemical structures were determined by spectroscopic methods. Similarly to our previous studies with the phytoalexin brassinin, these results suggest that virulent blackleg isolates are significantly more effective in metabolizing benzyldithiocarbamates than the related avirulent isolates. Keywords: benzyldithiocarbamates, brassinin, Leptosphaeriamaculans, Phomalingam, phytoalexins.
NMR kinetic study of ligand exchange on a (µ-oxo)bis(µ-acetato)diruthenium(III) complex. A special kinetic case of introduction of a more labile ligand
Authors: Santos Joana Mara , Cipriano Cecília , Faria Roberto B. , Figueroa-Villar J. Daniel
Published: May 2006

We have prepared the new [Ru2(μ-O)(μ-O2CCH3)2(4-pic)6](PF6)2 complex and followed the kinetics of exchange of the 4-picoline ligands, trans to the oxo bridge, with dimethyl sulfoxide (DMSO-d6) by 1H NMR at 30, 40, 50, and 60 °C. The 1H NMR spectra of this complex in DMSO gradually change in the acetyl methyl region as solvent substitution of the 4-picoline trans to the oxo bridge takes place. This substitution is in accordance with the lability of the ligands trans to the RuIII-O-RuIII bridge in this kind of complex. The kinetic data fit in a series of double reversible reactions, pseudo first order in the forward direction and second order in the reverse direction, with ΔH≠ = 115, 105, 116, and 106 kJ mol−1 and ΔS≠ = 35.7, 17.2, 38.8, and 16.9 JK−1 mol−1 associated with k1, k−1, k2, and k−2 rate constants, respectively.[Formula: see text]A, B and C stand for the nonexchanged, monoexchanged, and diexchanged complexes, respectively. The large ΔH≠ and positive ΔS≠ values agree with the dissociative nature of the mechanism in both forward and reverse reactions. The differences in 1H and I3C NMR chemical shifts of the three complexes are explained in terms of the effect of the ligand exchange on the N—Ru bond lengths and the geometry of the dimetal core. It is evident from our data that the exchange on one metallic site modifies the reactivity at the other site in this kind of dinuclear complex. Keywords: diruthenium complex, variable temperature NMR, ligand exchange kinetics.
A spectral displacement study of the binding constants of cyclodextrin–hydrocarbon and –fluorocarbon surfactant inclusion complexes
Authors: Wilson Lee D. , Siddall Stephanie R. , Verrall Ronald E.
Published: May 2006

The spectral displacement technique with phenolphthalein as the chromophore has been used to obtain 1:1 equilibrium binding constants (K2) for a homologous series of hydrocarbon (hc) (CnH2n+1COONa, n = 5–13) and fluorocarbon (fc) anionic surfactants (CnF2n+1COONa, n = 3–8) with β-cyclodextrin (β-CD). The magnitude of K2 increases as the alkyl chain length increases in each homologous series. K2 values in the ranges of 102–105 M−1 and 101–104 M−1 were obtained for the β-CD–fc and for the β-CD–hc surfactant complexes, respectively. The different binding affinity of β-CD with hc and fc surfactants is discussed in terms of such physicochemical properties of the guest species as hydrophobicity, geometrical size, conformational effects, molecular polarizability, and solvation of the head group. Keywords: spectral displacement, phenolphthalein, cyclodextrin, surfactant, binding constant.
cis-2,3-Di-tert-butylcyclopropanones
Authors: Sorensen T.S. , Sun F.
Published: May 2006

The preparation of the strained cis-2,3-di-tert-butylcyclopropanone 2 from the acyclic compound, α,α′-dibromodineopentyl ketone 1, using a previously reported methodology, is dramatic evidence of both the existence of oxyallyl intermediates in the mechanism of this reaction, and of the integrity with which oxyallyls ring-close to cyclopropanones by a disrotatory route. Because of the bulky cis substituents, cyclopropanone 2 exhibits a number of unusual spectroscopic features (as compared to the trans isomer 5). With the aid of ab initio calculations on 2 and 5, it can be shown that the C2—C3 bond in 2 interacts with the carbonyl π-orbitals, thus causing the carbonyl oxygen to bend 12° out of the plane; this interaction is absent in 5 and the latter has a planar carbonyl group. As with other cyclopropanones, 2 can be photochemically decarbonylated. This process itself appears to be stereospecific even though highly strained alkenes are produced. Cyclopropanone 2 is thermally rearranged to the trans isomer 5 and the kinetics for this are reported; our favoured mechanism involves oxyallyl intermediates. Other reactions of 2 also appear to proceed through these oxyallyl species; for example, alcohols initially add to 2 to give α-alkoxy ends, solutions of 2 enter into very facile diene cycloadditions, and the dimerization of neat 2 also appears to involve these oxyallyl species. Keywords: cyclopropanones, oxyallyl, stereomutation, stereospecific decarbonylation, nonplanar carbonyl.
Asymmetric synthesis of lignans using oxazolidinones as chiral auxiliaries
Authors: Charlton James L. , Chee Gaik-Lean
Published: May 2006

A simple procedure for the asymmetric synthesis of lignans via chiral β-benzyl-γ-butyrolactones has been developed. The key benzylbutyrolactone intermediates were efficiently synthesized using a six-step procedure, starting from 3,4-(methylenedioxy)cinnamic acid. The key step in this sequence was a highly diastereoselective alkylation of an N-acyloxazolidinone enolate. The resulting β-benzyl-γ-butyrolactones were subsequently transformed into the benzylidene lignans gossypifan and savinin (hibalactone) via aldol condensation–dehydration reactions, and into the dibenzylbutyrolactone lignan 4′-demethylyatein, through alkylation. Oxidation of 4′-demethylyatein with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) afforded cis-and trans-benzylidenebenzylbutyrolactones, whereas oxidation with DDQ/TFA gave 4′-demethyl-deoxyisopodophyllotoxin. Keywords: lignans, synthesis, asymmetric, biosynthesis, oxidation, benzylbutyrolactones.
Synthesis of 2-methyl-2-[1-(3-benzoyl-4-phenyl-1,4-dihydropyridyl)]acetic acid methyl ester, acetic acid, and acetamide analogs as potential antiarthritic agents
Authors: Agudoawu Sammy A. , Yiu Sai-hay , Knaus Edward E.
Published: May 2006

The cuprous iodide catalyzed reaction of 2-methyl-2-[1-(3-benzoyl-4-phenylpyridinium)]acetic acid methyl ester bromide (5), prepared by reaction of 3-benzoylpyridine (4) with racemic methyl 2-bromopropionate, with phenylmagnesium chloride at −23 °C afforded the 2-methyl-2-[1-(3-benzoyl-4-phenyl-1,4-dihydropyridyl)acetic acid methyl ester (6, 74%), which was a mixture of four diastereomers. Recrystallization of this diastereomeric mixture from diethyl ether afforded a solid product (6a-solid, 30%, 4R*,2R* and 4S*,2S*) and an oil product (6b-oil, 39%, 4R*,2S* and 4S*,2R*), each consisting of a mixture of two diastereomers that differ in relative configuration (R* or S*) at the 1,4-dihydropyridine C-4 position and the-CH(Me)CO2Me moiety. Addition of the Grignard reagent from either of the two diastereotopically different faces of the planar pyridinium salt (5) gives rise to two diastereomeric products 6a-solid and 6b-oil in which the C-4 phenyl substituent is pseudo-axial to the boat-shaped 1,4-dihydropyridine ring. Alkaline hydrolysis, or ammonolysis, of the acetic acid methyl ester (6) afforded the respective acetic acid (7), or acetamide (8), derivative. Keywords: 1,4-dihydropyridines, diastereomers.
Sedimentation of fine colloidal particles adsorbed onto a long polymer chain
Authors: Nowicki Waldemar , Nowicka Grażyna
Published: May 2006

A system containing aggregates composed of several fine colloidal particles attached to a single very long polymer molecule is considered. It is shown that the sedimentation equilibrium of the system depends on the extent of restriction over the Brownian motions of particles. On the basis of analysis of sedimentation equilibrium, a simple stability model for such systems is developed. The model elucidates the deterioration of the ability of ultralarge polymers to flocculate fine suspensions. Keywords: high polymers, fine colloidal particles, sedimentation, diffusion, flocculation, stabilization of suspensions.
Theory of electrochemical impedance of surface reactions: second-harmonic and large-amplitude response
Authors: Harrington David A.
Published: May 2006

The theory for the electrochemical impedance of surface reactions involving a single adsorbed species is presented. A new methodology is used, in which many harmonics are considered, and the differential equations are reduced to algebraic matrix equations. The amplitude of the ac potential perturbation is not assumed to be small, and nonlinear effects are taken into account. The amplitude dependence of the impedance and the second-harmonic response are investigated. The quasi-reversible electrosorption reaction and the hydrogen evolution reaction are considered in detail, assuming that the adsorbed species obeys the Langmuir isotherm. Keywords: electrochemistry, impedance, adsorption, hydrogen evolution reaction, second harmonic.
MIRROR SYMMETRY FOR TOPOLOGICAL SIGMA MODELS WITH GENERALIZED KÄHLER GEOMETRY
Authors: CHIANTESE STEFANO , GMEINER FLORIAN , JESCHEK CLAUS
Published: May 2006

We consider topological sigma models with generalized Kähler target spaces. The mirror map is constructed explicitly for a special class of target spaces and the topological A and B model are shown to be mirror pairs in the sense that the observables, the instantons and the anomalies are mapped to each other. We also apply the construction to open topological models and show that A branes are mapped to B branes. Furthermore, we demonstrate a relation between the field strength on the brane and a two-vector on the mirror manifold.
HGF synthesis in human lung fibroblasts is regulated by oncostatin M
Authors: Cohen Murielle , Marchand-Adam Sylvain , Lecon-Malas Véronique , Marchal-Somme Joëlle , Boutten Anne , Durand Geneviève , Crestani Bruno , Dehoux Monique
Published: May 2006

Oncostatin M (OSM) is a IL-6 family cytokine locally produced in acute lung injury. Its profibrotic properties suggest a role in lung wound repair. Hepatocyte growth factor (HGF), produced by fibroblasts, is involved in pulmonary epithelial repair. We investigated the role of OSM in HGF synthesis by human lung fibroblasts. We showed that OSM upregulated HGF mRNA in MRC5 cells and in human lung fibroblasts, whereas IL-6 and leukemia inhibitory factor did not. OSM induced HGF secretion to a similar extent as IL-1β in both a time- and dose-dependent manner. HGF was released in its cleaved mature form, and its secretion was completely inhibited in the presence of cycloheximide, indicating a de novo protein synthesis. OSM in combination with prostaglandin E2, a powerful HGF inductor, led to an additive effect. OSM and indomethacin in combination further increased HGF secretion. This could be explained, at least in part, by a moderate upregulation of specific OSM receptor β mRNA expression through cyclooxygenase inhibition.These results demonstrate that OSM-induced HGF synthesis did not involve a PGE2pathway. OSM-induced HGF secretion was inhibited by PD-98059 (a specific pharmacological inhibitor of ERK1/2), SB-203580 (a p38 MAPK inhibitor), and SP-600125 (a JNK inhibitor) by 70, 82, and 100%, respectively, whereas basal HGF secretion was only inhibited by SP-600125 by 30%. Our results demonstrate a specific upregulation of HGF synthesis by OSM, most likely through a MAPK pathway, and support the suggestion that OSM may participate in lung repair through HGF production.
Modulation of CD4
+
CD28
null
T Lymphocytes by Tumor Necrosis Factor-α Blockade in Patients With Unstable Angina
Authors: Rizzello Vittoria , Liuzzo Giovanna , Brugaletta Salvatore , Rebuzzi Antonio , Biasucci Luigi M. , Crea Filippo
Published: May 2006

Background—

Tumor necrosis factor-α (TNF-α) is a proinflammatory cytokine that favors the expansion of CD4
+
CD28
null
T cells, an aggressive and unusual proinflammatory lymphocyte subset frequently observed in patients with unstable angina (UA). The purpose of the present ex vivo study was to evaluate whether inflammation in patients with UA may be modulated by selective blockade of TNF-α.

Methods and Results—

Peripheral blood samples were collected from 17 patients with UA (Braunwald’s class IIIB). CD4
+
CD28
null
T cells were assessed by flow cytometry and expressed as a percentage of all CD4
+
T cells after 24 hours of incubation of whole blood with and without increasing doses (0.1, 1, 10, and 100 μg/mL) of infliximab, an anti–TNF-α monoclonal antibody. In addition, CD28 expression was assessed and expressed as mean fluorescence intensity (geometric mean of the CD28 fluorescence value on all CD4
+
T cells). CD4
+
CD28
null
T-cell percentage decreased from a median of 6.2% (range, 1.2% to 23.9%) to 4.9% (range, 1.1% to 21.9%), 4.5% (range, 1.1% to 21.6%), and 4.1% (range, 0.4% to 21.4%) after incubation with 1, 10, and 100 μg/mL of infliximab (
P
for trend=0.043). Analysis of CD28 mean fluorescence intensity showed that the expression of CD28 on cell surface significantly increased after incubation with increasing doses of infliximab (
P
for trend=0.03).

Conclusions—

The findings of this ex vivo study show that CD4
+
CD28
null
T-cell expansion in patients with UA may be reduced by selective TNF-α blockade. Further studies are warranted to evaluate the clinical benefit of CD4
+
CD28
null
T-cell modulation.
Percutaneous Septal Sinus Shortening
Authors: Rogers Jason H. , Macoviak John A. , Rahdert David A. , Takeda Patricia A. , Palacios Igor F. , Low Reginald I.
Published: May 2006

Background—

The septal-to-lateral (SL) mitral annular diameter is increased in functional mitral regurgitation (MR). We describe a novel percutaneous technique (the percutaneous septal sinus shortening system) that ameliorates functional MR in an ovine model.

Methods and Results—

Sheep underwent rapid right ventricular pacing to obtain moderate to severe functional MR with SL enlargement. The percutaneous septal sinus shortening system was placed via standard interventional techniques consisting of a bridge (suture) element between interatrial septal wall and great cardiac vein anchors. Through progressive tensioning of the bridge element, direct SL shortening was achieved. Sheep underwent short-term (n=19) and long-term (n=4) evaluation after device implantation. In short-term studies, SL diameter decreased an average of 24% (32.5±3.5 to 24.6±2.4 mm;
P
<0.001), and MR grade significantly improved (2.1±0.6 to 0.4±0.4;
P
<0.001). Despite continued rapid pacing, chronic device implantation resulted in durable SL shortening (30.4±1.9 mm before implantation to 25.3±0.8 mm at 30 days;
P
=0.01) and MR reduction (1.8±0.5 before implantation to 0.2±0.1 at 30 days;
P
=0.01). Increased cardiac output, decreased wedge pressure, and decreased brain natriuretic peptide levels were observed in animals undergoing long-term device implantation.

Conclusions—

The percutaneous septal sinus shortening system is effective in ameliorating functional MR in an ovine tachycardia model. The procedure, which uses standard catheter techniques, can be deployed largely under fluoroscopic guidance. The unique bridge element appears durable and allows direct and precise SL shortening to a diameter optimal for MR reduction.
Role of transcription factor Sp1 and CpG methylation on the regulation of the human podocalyxin gene promoter
Authors: Butta Nora , Larrucea Susana , Alonso Sonia , Rodriguez Ramón B , Arias-Salgado Elena G , Ayuso Matilde S , González-Manchón Consuelo , Parrilla Roberto
Published: May 2006

Background

Podocalyxin (podxl) is a heavily glycosylated transmembrane protein mainly found on the apical membrane of rat podocytes and also in endothelial, hematopoietic, and tumor cells. Despite of its interest no much is known about the transcriptional regulation of podxl in different cells. Thus, we aimed at studying the functional features of the 5'-regulatory region of the human Podxl gene.

Results

The promoter region of the human Podxl gene has been cloned and its structure and function were analyzed. The primary DNA sequence is rich in G+C and is devoid of TATA or CAAT boxes. The sequence contains recognition sites for several putative transcription factors; however, the basic promoter activity seems to rely entirely on Sp1 transcription factor since supershift analysis was positive only for this factor. The region encompassed by 66 to -111 nts conferred the minimal transcriptional activity that increases as the number of Sp1 sites augmented with the length of the promoter fragment. In Sp1-lacking insect cells the Podxl promoter constructs showed activity only if cotransfected with an Sp1 expression plasmid. Finally, mutation of the Sp1 sites reduced the promoter activity.

We analyzed whether methylation of the CpG dinucleotides present in the first ~600 nts of the promoter region of Podxl could explain the variable rates of expression in different types of cells. Inactivation of methyltransferases by 5'-aza-2'deoxicitidine showed a dose-dependent increase in the podxl content. Moreover, in vitro methylation of the promoter constructs -111,-181 and -210 led to an almost complete reduction of the promoter activity. A correlation was found between the degree of methylation of the CpG promoter dinucleotides and the rate of podxl expression in different cell lines.

Conclusion

Our results indicate that transcriptional regulation of Podxl is supported primarily by Sp1 site(s) and that DNA-methylation of the CpG promoter islands contributes to control the tissue specific expression of podxl.
HER 2/neu protein expression in colorectal cancer
Authors: Schuell B , Gruenberger T , Scheithauer W , Zielinski Ch , Wrba F
Published: May 2006

Background

Conflicting data exist about the prevalence of HER-2/neu overexpression in colorectal cancer ranging from 0 to 83 %. In our study we tried to clarify the extent of expression and its relationship to clinicopathological parameters.

Methods

This study involved 77 specimens of malignant colorectal cancer lesions of surgically resected patients. HER-2/neu immunohistochemistry was performed using the Hercep-Test Kit.

Results

Out of 77 specimens, 56 were Her-2/neu negative (70%), 20 (26%) showed a barely immunostaining (1+), only 1 (1%) was moderately (2+) and 2 (3%) were strongly positive (3+). Her-2/neu staining (moderately and strongly positive) was only detected in primary tumours of patients with confirmed metastases. No relationship was found between membranous HER-2 expression and patients' gender or differentiation. The median survival time of patients with positive HER-2/neu immunostaining was 21 versus 39 months in patients without HER-2/neu expression (p = 0.088).

Conclusion

The c-erbB protein expression was observed in colorectal cancer but rarely in the therapeutic range (2+ and 3+). There was no significant association with tumour grade, gender, localization of the primary tumour or survival. These data indicate that c-erbB-2 is unlikely to play a major role in the therapeutic management of colorectal cancer.
Laser-assisted blastocyst dissection and subsequent cultivation of embryonic stem cells in a serum/cell free culture system: applications and preliminary results in a murine model
Authors: Tanaka Noriko , Takeuchi Takumi , Neri Queenie V , Sills Eric Scott , Palermo Gianpiero D
Published: May 2006

Background

To evaluate embryonic stem cell (ESC) harvesting methods with an emphasis on derivation of ESC lines without feeder cells or sera. Using a murine model, laser-assisted blastocyst dissection was performed and compared to conventional immunosurgery to assess a novel laser application for inner cell mass (ICM) isolation.

Methods

Intact blastocysts or isolated ICMs generated in a standard mouse strain were plated in medium with or without serum to compare ESC harvesting efficiency. ESC derivation was also undertaken in a feeder cell-free culture system.

Results

Although ICM growth and dissociation was comparable irrespective of the media components, an enhanced ESC harvest was observed in our serum-free medium (p < 0.01). ESC harvest rate was not affected by ICM isolation technique but was attenuated in the feeder cell-free group.

Conclusion

Achieving successful techniques for human ESC research is fundamentally dependent on preliminary work using experimental animals. In this study, all experimentally developed ESC lines manifested similar features to ESCs obtained from intact blastocysts in standard culture. Cell/sera free murine ESC harvest and propagation are feasible procedures for an embryology laboratory and await refinements for translation to human medical research.
Molecular diagnosis of Theileria and Babesiaspecies infecting cattle in Northern Spain using reverse line blot macroarrays
Authors: García-Sanmartín Josune , Nagore Daniel , García-Pérez Ana L , Juste Ramón A , Hurtado Ana
Published: May 2006

Background

Piroplasmosis in cattle is caused by tick-borne haemoprotozoan parasites of the genera Theileria and Babesia. Molecular detection techniques offer higher sensitivity and specificity than microscopy examination methods and serological tests. A reverse line blot (RLB) macroarray that included generic and species-specific probes for Theileria annulata, Theileria buffeli, Babesia bovis, Babesia bigemina, Babesia divergens and Babesia major was used to study the presence and identity of the piroplasm species infecting 263 bovine blood samples from 79 farms, most of them in Northern Spain. Microscopy examination of blood smears and haematology were also performed whenever possible to identify animals with parasitaemia.

Results

RLB hybridisation identified infection in 54.0% of the samples, whereas only 28.8% were positive by microscopy examination. The most frequently found species was T. buffeli, present in 42.6% of the samples. T. annulata was found in 22 samples (8.4%) from 12 farms, including 9 farms (14 samples) located in Northern Spain where presence of the vector is not very common. Babesia infections were less frequently detected: B. major was found in 3.0% of the samples, B. bigemina in 2.7%, B. bovis in 2.3% and B. divergens in 1.1%. Mixed infections were detected in 14 samples, accounting for six different combinations of species.

Conclusion

This is the first report in which B. major and B. divergens have been detected in Spain using molecular identification techniques and the first time that B. bovis has been detected in Northern Spain. The detection of T. annulata in Northern Spain suggests that the distribution of Mediterranean theileriosis might be changing. Samples with positive RLB hybridisation but negative microscopy had haematology values within the normal ranges suggesting that they corresponded to chronic carriers that may serve as reservoirs of the infection. In this sense, sensitive and specific laboratorial tests like RLB that clearly identify the parasite and can detect subclinical infections are essential to establish good control measures.
Cost-Effectiveness of Adding Granulocyte Colony-Stimulating Factor to Primary Prophylaxis With Antibiotics in Small-Cell Lung Cancer
Authors: Timmer-Bonte Johanna N.H. , Adang Eddy M.M. , Smit Hans J.M. , Biesma Bonne , Wilschut Frank A. , Bootsma Gerben P. , de Boo Theo M. , Tjan-Heijnen Vivianne C.G.
Published: May 2006

Purpose

Recently, a Dutch, randomized, phase III trial demonstrated that, in small-cell lung cancer patients at risk of chemotherapy-induced febrile neutropenia (FN), the addition of granulocyte colony-stimulating factor (GCSF) to prophylactic antibiotics significantly reduced the incidence of FN in cycle 1 (24% v 10%; P = .01). We hypothesized that selecting patients at risk of FN might increase the cost-effectiveness of GCSF prophylaxis.

Methods

Economic analysis was conducted alongside the clinical trial and was focused on the health care perspective. Primary outcome was the difference in mean total costs per patient in cycle 1 between both prophylactic strategies. Cost-effectiveness was expressed as costs per percent-FN-prevented.

Results

For the first cycle, the mean incremental costs of adding GCSF amounted to 681 euro (95% CI, −36 to 1,397 euro) per patient. For the entire treatment period, the mean incremental costs were substantial (5,123 euro; 95% CI, 3,908 to 6,337 euro), despite a significant reduction in the incidence of FN and related savings in medical care consumption. The incremental cost-effectiveness ratio was 50 euro per percent decrease of the probability of FN (95% CI, −2 to 433 euro) in cycle 1, and the acceptability for this willingness to pay was approximately 50%.

Conclusion

Despite the selection of patients at risk of FN, the addition of GCSF to primary antibiotic prophylaxis did not result in cost savings. If policy makers are willing to pay 240 euro for each percent gain in effect (ie, 3,360 euro for a 14% reduction in FN), the addition of GCSF can be considered cost effective.
Excellent Reversible Photochromic Behavior of 4-Octyl-4′-(5-carboxylpentamethyleneoxy)-azobenzene in Organized Monolayer Assemblies
Authors: Liu Zhong-Fan , Loo Boon H , Baba Ryo , Fujishima Akira
Published: May 2006

We report the first observation of a photochromic behavior of an amphiphilic azobenzene derivative in the close-packing LB films on a solid support. The excellent reversibility was achieved only after the LB films were ‘pretreated’ with UV irradiation.
Time Courses of the Numbers of Ion Radicals Produced in a Ternary System of a Decationated Y-Type Zeolite and Two Organic Compounds
Authors: Kashiwagi Hiroshi
Published: May 2006

The number of ion radicals formed from a single organic compound or two organic compounds adsorbed on a zeolite was time-dependent. Cation radicals from a stronger electron donor adsorbed in advance were replaced by those from a weaker donor. The coexistence of donor and acceptor molecules increased the spin-generating sites of both cation and anion radicals.
Silver-promoted Cobalt Oxide Catalysts for Direct Decomposition of Nitrogen Monoxide
Authors: Hamada Hideaki , Kintaichi Yoshiaki , Sasaki Motoi , Ito Takehiko
Published: May 2006

Silver as a catalyst additive showed an excellent effect to improve the catalytic activity of cobalt oxide for the decomposition of nitrogen monoxide below 773 K. Reaction inhibition by oxygen was very much relieved by using Ag–Co oxide catalysts.
Photolysis of 1,1,1-Triphenyl-2-alkenes and Methyl Triphenylacetate
Authors: Shi Min , Okamoto Yoshiki , Takamuku Setsuo
Published: May 2006

Upon UV irradiation in methanol 1,1,1-triphenyl-2-alkene or methyl triphenylacetate underwent two kinds of α,α-elimination of two phenyl groups and phenyl-alkenyl groups or phenyl-methoxycarbonyl groups to give biphenyl, 1-phenylalkene or methyl benzoate, and two kinds of corresponding carbene intermediates, which inserted into the O–H bond of methanol to afford two kinds of methyl ethers, respectively.
Photoreaction of the Adduct between (η-Cyclopentadienyl)(1,2-dicyano-1,2-ethylenedithiolato)cobalt(III) and Tributylphosphine. Oxygenation of Coordinated Phosphine by Singlet Oxygen
Authors: Hatano Hiroshi , Kajitani Masatsugu , Akiyama Takeo , Sakaguchi Yoshio , Nakamura Junko , Hayashi Hisaharu , Sugimori Akira
Published: May 2006

The title complex [Co(cp)(S2C2(CN)2)(PBu3)] gives [Co(cp)(S2C2(CN)2)] and phosphine oxide (O=PBu3) under irradiation with methylene blue or rose bengal as sensitizer in the presence of oxygen. This reaction proceeds via oxidative elimination of the coordinated phosphine by singlet oxygen. Under irradiation with 254 nm light, the adduct plays the role of a triplet sensitizer.
Silver(l) Ion Selective Electrode Based on Dithlamacrocycles
Authors: Casabo Jaume , Perez-Jimenez Consuelo , Escriche Lluis , Alegret Salvador , Martinez-Fabregas Esteve , Teixidor Francesc
Published: May 2006

Poly(vinyl chloride) membrane all solid state electrode based on the macrocyclic polythiaether 6-oxa-3,9-dithiabicycle[9,3,1]-pentadeca-1(15)-11,13-triene, has been developped. The electrode exhibits a Nernstian linear response to silver(l) ion from 10−6 to 10−1 M, good selectivity (no response for Hg(ll)) and short response time (<10 s).
Formation of Two Exciplexes in Cadmium-Photosensitized Reaction of Aliphatic Diamines
Authors: Yamamoto Shunzo , Itami Masato , Sueishi Yoshimi , Nishimura Norio
Published: May 2006

Two emission bands have been observed during irradiation of mixtures of some aliphatic diamines and cadmium vapor with cadmium 326.1 nm radiation. From the temperature and pressure dependences of emission intensities of the two bands, we have concluded that they are assigned to two kinds of 1:1 exciplexes between an excited cadmium atom and a diamine molecule.
Charge Transfer Reaction Inverse Photoemission Spectroscopy (CTRIPS) at a Gold/Acetonitrile Solution Interface. Evidence for Photon Emission via Surface States
Authors: Uosaki Kohei , Murakoshi Kei , Kita Hideaki
Published: May 2006

The emission of light caused by electron transfer reaction at a gold electrode in acetonitrile solution containing one of three aromatic redox compounds (benzophenone, t-stilbene and benzonitrile) was studied. From the potential dependence of the spectrum, we proposed that the emission is due to charge transfer reaction inverse photoemission (CTRIP) process which takes place via surface states.
Mixed Oxide Capacitor of BaTiO3–PbO as a New Type CO2 Gas Sensor
Authors: Ishihara Tatsumi , Kometani Kazuhiro , Hashida Masayo , Takita Yusaku
Published: May 2006

Mixed oxide capacitor of BaTiO3–PbO is studied as the sensor for CO2 detection. The oxide gave the large capacitance change on exposure to CO2. The CO2 sensing characteristics strongly depended on the operation temperature as well as the operation frequency. A linear relationship exists between the sensitivity and the concentration of CO2 below 6%.