bluuebunny/crossref_metadata_2025 huggingface dataset:
Postsecondary education and some dimensions of literacy development: An exploration of longitudinal evidence
Authors: BRAY GAYLE BABBITT , PASCARELLA ERNEST T. , PIERSON CHRISTOPHER T.
Published: July 2004

ABSTRACTS

This exploratory study analyzed longitudinal data from 18 institutions to track the literacy development of 1,054 students during the first three years of college. Reading comprehension and attitude toward literacy activities were assessed at the beginning and end of the study. Students responded annually to questionnaires about college experiences and provided background data. Linear regression procedures were used to predict growth on the outcome measures. With potential confounding influences on literacy growth controlled, students of color made smaller reading comprehension gains than white students, and women made smaller improvements in literacy attitude than men. For the overall sample, growth in comprehension was predicted by credit hours completed, number of assigned books read, instruction perceived as effective, and the number of natural sciences and engineering courses taken. Number of assigned and unassigned books read and involvement in course learning and library experiences predicted improved attitude toward literacy activities. However, the major finding of the study was that the college‐experience factors associated with literacy growth varied depending on students' race, sex, and levels of reading comprehension and attitude toward literacy activities prior to college.
Adaptive control with selective memory
Authors: Hill Jennifer Hsu , Ydstie B. Erik
Published: July 2004

Adaptive control with selective memory updates the parameter estimates only when there is new information present. The information content increases and the estimator eventually stops. In this paper we use the Fisher information matrix and a variance estimator to measure the information content. The parameter estimates are updated only when the Information Matrix and/or the estimated variance of the prediction error increases. This gives an algorithm for adaptive control which converges to a linear time invariant controller. The resulting controller is robust with respect to bounded disturbances and small model/plant mismatch. Knowledge about overbounding sets for the parameter estimates or the disturbances are not needed. Simulation results using theoretical test cases illustrate near optimal performance for the converged parameters. Copyright © 2004 John Wiley & Sons, Ltd.
Identification of dual‐rate systems based on finite impulse response models
Authors: Ding Feng , Chen Tongwen
Published: July 2004

Two identification algorithms, a least squares and a correlation analysis based, are developed for dual‐rate stochastic systems in which the output sampling period is an integer multiple of the input updating period. The basic idea is to use auxiliary FIR models to predict unmeasurable noise‐free (true) outputs, and then use these and system inputs to identify parameters of underlying fast single‐rate models. The simulation results indicate that the proposed algorithms are effective. Copyright © 2004 John Wiley & Sons, Ltd.
Effects of vapor–liquid mass transfer on feasibility of reactive distillation
Authors: Nisoli Alberto , Doherty Michael F. , Malone Michael F.
Published: July 2004

A cascade model including the Stefan–Maxwell model for mass transfer is developed to assess the feasibility of reactive distillation. The model fixed points are determined as a function of the Peclet number and other parameters, using a pseudo arc‐length continuation method. The approach is illustrated with two examples: a parametric study of an idealized ternary system, and the esterification of acetic acid to produce isopropyl acetate. In the limit of little or no reaction, the fixed points are independent of the mass‐transfer resistance, and a model based on phase equilibrium can be used for feasibility. When the chemical reaction rates or extents are more significant, the fixed points do depend on the Peclet number, and mass transfer can influence the feasible products. However, best estimates of the mass‐transfer parameters and the processing conditions typical of reactive distillation indicate that these effects are small for the examples studied. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1795–1813, 2004
Investigations on pulse broadening for catalyst screening in gas/liquid systems
Authors: Pennemann H. , Hessel V. , Kost H.‐J. , Löwe H. , de Bellefon C.
Published: July 2004

In connection with the development of a complete screening setup for organometallic catalysis, a micromixer–tube setup was investigated to optimize its serial transient operation mode. Because homogeneously dissolved catalysts and substrates in the liquid phase of a gas/liquid system are pulse‐injected into the two‐phase system, our investigations aim in finding a minimum in the signal broadening and maximizing the number of experiments per unit of time. Within this context, investigations of the residence time distribution of the whole setup, as well as the individual contributions of its respective components toward signal broadening, were undertaken by determining the effects on the residence time distribution by the gas/liquid ratio, the orientation of the residence time loop and the total flow rate. © 2004 American Institute of Chemical Engineers AIChE J, 50:1814–1823, 2004
Functional implications of a novel EA2 mutation in the P/Q‐type calcium channel
Authors: Spacey Sian D. , Hildebrand Michael E. , Materek Luke A. , Bird Thomas D. , Snutch Terrance P.
Published: July 2004

Episodic ataxia type 2 (EA2) is an autosomal dominant condition characterized by paroxysmal attacks of ataxia, vertigo, and nausea, typically lasting minutes to days in duration. These symptoms can be prevented or significantly attenuated by the oral administration of acetazolamide; however, the mechanism by which acetazolamide ameliorates EA2 symptoms is unknown. EA2 typically results from nonsense mutations in the CACNA1A gene that encodes the α1A (Cav2.1) subunit of the P/Q‐type calcium (Ca2+) channel. We have identified a novel H1736L missense mutation in the CACNA1A gene associated with the EA2 phenotype. This mutation is localized near the pore‐forming region of the P/Q‐type Ca2+ channel. Functional analysis of P/Q‐type channels containing the mutation show that the H1736L alteration affects several channel properties, including reduced current density, increased rate of inactivation, and a shift in the voltage dependence of activation to more positive values. Although these findings are consistent with an overall loss of P/Q‐type channel function, the mutation also caused some biophysical changes consistent with a gain of function. We also tested the direct effect of acetazolamide on both wild‐type and H1736L mutated P/Q‐type channels and did not observe any direct action on channel properties of this pharmacological agent used to treat EA2 patients. Ann Neurol 2004
Bilateral globus pallidus stimulation for Huntington's disease
Authors: Moro Elena , Lang Anthony E. , Strafella Antonio P. , Poon Yu‐Yan W. , Arango Pablo M. , Dagher Alain , Hutchison William D. , Lozano Andres M.
Published: July 2004

Bilateral globus pallidus internus (GPi) deep brain stimulation (DBS) was performed in a patient with Huntington's disease (HD) with severe chorea. Stimulation at 40 and 130Hz improved chorea. Stimulation at 130Hz slightly worsened bradykinesia overall, whereas 40Hz had little effect. A [15O] H2O positron emission tomography showed increased regional cerebral blood flow in motor decision making and execution areas more evident at 40Hz. Adjustment of stimulation parameters in GPi DBS may have the potential to optimize the motor response in HD, improving chorea without aggravating bradykinesia. Ann Neurol 2004
Titelbild: Die Cobalt(I)‐katalysierte asymmetrische [2+2+2]‐Cycloaddition von Alkinen und Nitrilen: Synthese von enantiomerenangereicherten Atropisomeren von 2‐Arylpyridinen (Angew. Chem. 29/2004)
Authors: Gutnov Andrey , Heller Barbara , Fischer Christine , Drexler Hans‐Joachim , Spannenberg Anke , Sundermann Bernd , Sundermann Corinna
Published: July 2004

Unter Lichteinwirkung entsteht in der Natur im Beispiel der linksgewundenen Hopfenpflanze nur eines der beiden möglichen Spiegelbilder. Dagegen können beide Enantiomere von atropisomeren Biaryl‐Stickstoffheterocyclen im Labor gezielt in einer [2 + 2 + 2]‐Cycloaddition erhalten werden, die A. Gutnov und B. Heller et al. in der Zuschrift auf S. 3883 ff. vorstellen. Die Reaktion verläuft photochemisch und wird durch einen chiralen Cobaltkomplex katalysiert. (Das Hintergrundbild stammt aus Rechts oder links. In der Natur und anderswo. von H. Brunner, Wiley‐VCH, 1999.)
Cover Picture: Cobalt(I)‐Catalyzed Asymmetric [2+2+2] Cycloaddition of Alkynes and Nitriles: Synthesis of Enantiomerically Enriched Atropoisomers of 2‐Arylpyridines (Angew. Chem. Int. Ed. 29/2004)
Authors: Gutnov Andrey , Heller Barbara , Fischer Christine , Drexler Hans‐Joachim , Spannenberg Anke , Sundermann Bernd , Sundermann Corinna
Published: July 2004

Nature decided in favor of the left‐handed helical isomer for the hop vine shown in the cover picture. In contrast, the [2 + 2 + 2] cycloaddition yielding biaryl nitrogen heterocycles gives access to both enantiomers. In their Communication on p. 3795 ff. A. Gutnov, B. Heller et al. describe this photochemical reaction which is conducted with a chiral cobalt catalyst. (The picture of the hop plant is taken from the book by H. Brunner, Rechts oder Links. In der Natur und anderswo, Wiley‐VCH, 1999.)
Breast surgery in the ‘Arimidex, Tamoxifen Alone or in Combination’ (ATAC) trial
Authors: Locker Gershon Y. , Sainsbury J. Richard , Cuzick Jack
Published: July 2004

BACKGROUND

Various factors affect patients' decisions regarding whether to undergo surgery for the treatment of early‐stage breast carcinoma. The ‘Arimidex, Tamoxifen Alone or in Combination’ (ATAC) trial, the largest multinational randomized trial of adjuvant therapy for patients with operable breast carcinoma to date, offers the opportunity to investigate whether nationality is one such factor.

METHODS

After receiving primary therapy for early‐stage breast carcinoma, 9366 women (from a total of 21 countries) were randomized to receive anastrozole, tamoxifen, or anastrozole plus tamoxifen for 5 years. In the current study, mastectomy and breast conservation rates were compared among participating countries. The possibility that variations from country to country could be explained by inequalities in terms of pathologic, clinical, and hospital‐related correlates of surgical choice was explored first on univariate analysis and then on multivariate logistic analysis.

RESULTS

National mastectomy rates ranged from 20% to 97%; 51% of the 2222 enrollees from the United States had undergone mastectomy, compared with 42% of the 3228 enrollees from the United Kingdom (odds ratio [OR], 1.43; 95% confidence interval [CI], 1.28–1.60;P< 0.001). On univariate analysis, larger tumor size, positive lymph node status, higher tumor grade, older age, and adjuvant chemotherapy use were found to be correlated with mastectomy use. In contrast, positive hormone receptor status, increased body weight, and enrollment at a center that had more than 40 enrollees were found to be associated with breast conservation. The same correlates were identified on multivariate logistic analysis (P< 0.05), except that the number of enrollees at a patient's treatment center no longer possessed predictive value. After correction for these correlated factors, residence in the United States (compared with residence in the United Kingdom) remained an independent predictor of mastectomy use (OR, 1.44; 95% CI, 1.26–1.64;P< 0.001).

CONCLUSIONS

American women enrolled in the ATAC trial were more likely to undergo aggressive surgery compared with their counterparts from the United Kingdom. More generally, nationality was found to be an independent determinant of surgical choice in the current study. Cancer 2004. © 2004 American Cancer Society.
Increasing evidence for a human breast carcinoma virus with geographic differences
Authors: Levine Paul H. , Pogo Beatriz G.‐T. , Klouj Afifa , Coronel Stephanie , Woodson Karen , Melana Stella M. , Mourali Nejib , Holland James F.
Published: July 2004

BACKGROUND

An early immunologic study suggesting that a virus similar to the mouse mammary tumor virus (MMTV) was associated highly with breast carcinoma in Tunisian patients, compared with patients in the United States, led the authors to examine different breast carcinoma populations by using more current molecular techniques.

METHODS

Thirty‐nine paraffin blocks were selected for sequencing of the 250‐base pair segment of the MMTV from patients with breast carcinoma who were seen and treated at the Institut Salah Azaiz in Tunisia. Fifteen of those blocks were examined under code by a second laboratory, which used a different methodology and was blinded to the results of the first laboratory, and 14 blocks were analyzed successfully.

RESULTS

The comparison of Tunisian patients and patients from other countries clearly showed a significantly higher proportion of tumors with MMTV‐like sequences in the Tunisian series of patients. There was complete reproducibility of data between the two laboratories. Using the results from the first laboratory and similar studies from the literature, detection of the MMTV‐like env gene sequence showed an important geographic pattern with a significantly higher percentage of positive patients with breast carcinoma in Tunisia (74%) compared with patients with breast carcinoma in the United States (36%), Italy (38%), Australia (42%), Argentina (31%), and Vietnam (0.8%)

CONCLUSIONS

The findings provided increased evidence for a human breast carcinoma virus with geographic differences in prevalence. The geographic differences were compatible with studies of MMTV in wild mice; thus, the data were plausible biologically. Cancer 2004. © 2004 American Cancer Society.
Internal tandem duplication of fms‐like tyrosine kinase 3 is associated with poor outcome in patients with myelodysplastic syndrome
Authors: Shih Lee‐Yung , Lin Tung‐Liang , Wang Po‐Nan , Wu Jin‐Hou , Dunn Po , Kuo Ming‐Chung , Huang Chein‐Fuang
Published: July 2004

BACKGROUND

The prognostic significance of internal tandem duplication (ITD) of the fms‐like tyrosine kinase 3 gene (FLT3) for patients with myelodysplastic syndrome (MDS) is not clearly defined. In the current study, the authors sought to assess the value of FLT3/ITD mutation status as a prognostic genetic marker for patients with MDS.

METHODS

FLT3/ITD mutation status was evaluated by performing DNA polymerase chain reaction assays on 198 bone marrow samples obtained from patients with MDS at initial diagnosis. All aberrant products were sequenced, and GeneScan analysis was performed to measure FLT3/ITD mutant levels.

RESULTS

Five patients (2.5%)—2 of the 99 patients who had refractory anemia with excess blasts and 3 of the 51 patients who had chronic myelomonocytic leukemia—had FLT3/ITD mutations. FLT3/ITD was not observed in any of the 48 patients who had refractory anemia (with or without ringed sideroblasts). There was no significant difference in clinicohematologic characteristics, cytogenetic characteristics, or International Prognostic Scoring System score between the FLT3/ITD‐positive group and the FLT3/ITD‐negative group. Four of the 5 patients carrying the FLT3/ITD mutation experienced progression of disease to acute myeloid leukemia (AML), compared with 70 of the 193 patients who did not have FLT3/ITD (P = 0.066). In addition, progression to AML was more rapid in patients with FLT3/ITD‐positive disease than in patients with FLT3/ITD‐negative disease (mean ± standard error, 3.0 ± 0.5 months vs. 62.8 ± 5.6 months; P < 0.0001). Patients with FLT3/ITD‐positive disease also had significantly shorter survival compared with patients who had FLT3/ITD‐negative disease (mean ± standard error, 5.2 ± 1.4 months vs. 33.7 ± 3.1 months; P < 0.0001). On multivariate analysis, FLT3/ITD was identified as an independent predictor of reduced time to development of AML (P = 0.0001) and reduced overall survival (P = 0.002).

CONCLUSIONS

The results of the current study demonstrate that FLT3/ITD is associated with a high risk of transformation to AML, rapid progression of AML, and poor survival in patients with MDS. Cancer 2004. © 2004 American Cancer Society.
The J2EE ECperf benchmark results: transient trophies or technology treasures?
Authors: Brebner Paul , Gosper Jeffrey
Published: July 2004

ECperf, the widely recognized industry standard J2EE benchmark, has attracted a large number of results submissions and their subsequent publications. However, ECperf places little restriction on the hardware platforms, operating systems and databases utilized in the benchmarking process. This, combined with the existence of only two primary metrics, makes it difficult to accurately compare the performance of the Application Server products themselves. By mining the full‐disclosure archives for trends and correlations, we have discovered that J2EE technology is very scalable both in a scale‐up and scale‐out manner. Other observed trends include a linear correlation between middle‐tier total processing power and throughput, as well as between J2EE Application Server license costs and throughput. However, the results clearly indicate that there is an increasing cost per user with increasing capacity systems and scale‐up is proportionately more expensive than scale‐out. Finally, the correlation between middle‐tier processing power and throughput, combined with results obtained from a different ‘lighter‐weight’ benchmark, facilitates an estimate of throughput for different types of J2EE applications. Copyright © 2004 John Wiley & Sons, Ltd.
Monocarbaborane Chemistry: Cage Opening of nido‐1‐CB8H12 by Tertiary Bases − an Example of a Straightforward nido → arachno Transformation; Isolation of a New Series of 4‐L‐arachno‐5‐CB8H12 Compounds (L = NMe3, NEt3, and Quinoline)
Authors: Štíbr Bohumil , Holub Josef , Bakardjiev Mario , Milius Wolfgang , Wrackmeyer Bernd
Published: July 2004

Room‐temperature reactions between the carborane nido‐1‐CB8H12 (1) and selected tertiary Lewis bases [L = NMe3, NEt3, and quinoline (quin)] in CH2Cl2 at room temperature for 24 h resulted in the isolation of a series of 4‐L‐arachno‐5‐CB8H12 compounds (2; L = NMe3, 2a, L = NEt3, 2b and L = quin, 2c). This main reaction mode can be classified as a straightforward nido → arachno transformation and was characterized by a cage opening of the original pentagonal face in 1 by L at the bridging site adjacent to the carbon apex with the formation of a hexagonal open face. The formation of 2a was clean, whereas that of 2c was accompanied by formation of the closo‐[4‐CB8H9]− (3) anion as a side‐product. The first representative of the zwitterionic 1‐L‐closo‐4‐CB8H8 (4) series, 1‐quin‐closo‐4‐CB8H8 (4c), was isolated as another side product from the quinoline reaction. The structure of compound 2b was determined by an X‐ray diffraction analysis and the constitution of all compounds is consistent with the results of mass spectrometry. Multinuclear (1H, 11B, and 13C), two‐dimensional [11B‐11B]‐COSY, and 1H{11B(selective)} magnetic resonance measurements lead to complete assignments of all resonances and are in excellent agreement with the structures proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Rational Design of Metal‐Organic Frameworks Based on 5‐(4‐Pyridyl)tetrazolate: From 2D Grids to 3D Porous Networks
Authors: Jiang Chao , Yu Zhaopeng , Wang Sujing , Jiao Chao , Li Jiaming , Wang Zhiyong , Cui Yong
Published: July 2004

The hydrothermal reactions of Zn(ClO4)2·6H2O/Cu(NO3)2·6H2O with 5‐(4‐pyridyl)tetrazole in an ethanol/water or ethanol/water/pyridine medium yield one 2D and one 3D metal‐organic coordination framework [Zn2(OH)(4‐ptz)3] (1) and [Cu(4‐ptz)·0.5(py)] (3) [4‐ptz = 5‐(4‐pyridyl)tetrazolate, py = pyridine], respectively. Complex 1 possesses two identical and independent rectangular grid sheets with twofold parallel interpenetration, in which the four‐connected nodes of the net are provided by Zn2(OH) units connected to one another through 4‐ptz and (4‐ptz)2 bridges. These composite sheets are stacked one on top of another by hydrogen‐bonding interactions to afford a 3D structure. There are many structural similarities between complex 1 and the recently reported 2D layered network [Zn(OH)(4‐ptz)(H2O)] (2), in particular the components of the network, the coordination mode of the 4‐ptz ligand and the in situ formation of hydroxy groups. Complex 2 can be synthesized by the hydrothermal reaction of Zn(ClO4)2·6H2O and 5‐(4‐pyridyl)tetrazole in an ethanol/water/pyridine medium. The structural characterization of complex 3 shows a porous structure that contains the guest pyridine molecules. Additionally, compounds 1 and 2 exhibit strong fluorescence at room temperature in the solid state. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Catalytic Activity of (η6‐p‐Cymene)(phosphane)ruthenium(II) Complexes Supported on Poly(biphenoxyphosphazene) or Chiral Poly(binaphthoxyphosphazene) Copolymers
Authors: Carriedo Gabino A. , Crochet Pascale , Alonso Francisco J. García , Gimeno José , Presa‐Soto Alejandro
Published: July 2004

The polyphosphazene random copolymer containing diphenylphosphane ligands {[NP(OC6H4PPh2)2]0.4[NP(O2C12H8)]0.6}n (1a) (O2C12H8 = 2,2′‐dioxy‐1,1′‐biphenyl), and the chiral binaphthoxy analogues {[NP(OC6H4PPh2)2]0.1[NP(O2C20H12)]0.9}n [O2C20H12 = (R)‐2,2′‐dioxy‐1,1′‐binaphthyl] (1b) and {[NP(OC6H4PPh2)2]0.2[NP(O2C20H10Br2)]0.8}n [O2C20H10Br2 = (R)‐2,2′‐dioxy‐6,6′‐dibromo‐1,1′‐binaphthyl] (1c), reacted in dichloromethane at room temperature with appropriate amounts of the dimeric complex [Ru(η6‐p‐cymene)Cl(μ‐Cl)]2 to give the corresponding polymeric (phosphane)RuII complexes {[NP(OC6H4PPh2[RuCl2(η6‐p‐cymene)]x)2]0.4[NP(O2C12H8)]0.6}n [x = 0.5 (2a), 1 (2b)], {[NP(OC6H4PPh2[RuCl2(η6‐p‐cymene)])2]0.1[NP(O2C20H12)]0.9}n (3) and {[NP(OC6H4PPh2[RuCl2(η6‐p‐cymene)])2]0.2[NP(O2C20H10Br2)]0.8}n (4). The isolated products are soluble reddish solids, and are thermally very stable with very high glass transition temperatures. The reaction of 1b or 1c with the cationic precursor [RuCl(PPh3)2(η6‐p‐cymene)][PF6] in refluxing THF gave the crosslinked insoluble cationic polymeric complexes {[NP(OC6H4PPh2)2]0.1[NP(O2C20H12)]0.9[RuCl(η6‐p‐cymene)(PF6)]0.05}n (5) and {[NP(OC6H4PPh2)2]0.2[NP(O2C20H10Br2)]0.8[RuCl(η6‐p‐cymene)(PF6)]0.08}n (6). All the complexes were active catalysts in transfer hydrogenation of acetophenone by propan‐2‐ol, but the C2‐pockets containing the catalytic centers gave no enantioselectivity because of the conformational behavior of the chiral derivatives. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Formation of Novel 1‐D Chains by μ‐Amido Bridging of Dinuclear Manganese(III)‐Schiff Base Complexes
Authors: Bermejo Manuel R. , González‐Noya Ana M. , Abad Víctor , Fernández M. Isabel , Maneiro Marcelino , Pedrido Rosa , Vázquez Miguel
Published: July 2004

Three novel neutral manganese(III) complexes of stoichiometry Mn(R‐amsal‐3,5‐di‐tBu)(H2O)n [H3‐R‐amsal‐3,5‐di‐tBu = 3‐aza‐4‐(2‐hydroxyphenyl)‐N‐(2‐hydroxyphenyl)but‐3‐enamide; (R = H, 4‐Me, 5‐tBu)] have been synthesised using potentially trianionic and pentadentate Schiff‐base ligands containing an amide group. Complexes were thoroughly characterised by elemental analysis, FAB mass spectrometry, infrared spectroscopy, magnetic susceptibility measurements and molar conductivities. Recrystallisation of these complexes from methanol yielded single crystals of [Mn2(amsal‐3,5‐di‐tBu)2(MeOH)2]n 1, [Mn2(4‐Me‐amsal‐3,5‐di‐tBu)2(MeOH)2]n 2 and [Mn2(5‐tBu‐amsal‐3,5‐di‐tBu)2(MeOH)2]n 3 with methanol as solvate. Their X‐ray characterisation shows that these complexes consist of infinite one‐dimensional chains with a repeating cyclic dimeric unit, where the amide oxygen atom is bridging two neighbouring manganese(III) ions. Paramagnetic 1H NMR spectroscopy confirmed the presence of MnIII in these complexes, while the cyclic voltammetry studies suggest the possibility of obtaining polynuclear MnIV complexes with this kind of ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Metalation of 2‐Propenylphenol
Authors: Wippert Rodrigues Cristina , Limberg Christian , Pritzkow Hans
Published: July 2004

In order to generate 2‐propenylphenolate, PO−, as a potential ligand for oxomolybdenum compounds, the lithiation of the parent phenol derivative, POH, was investigated. Treatment of POH with BuLi in THF yielded a tetramer of the corresponding alkoxide “POLi” with a heterocubane structure in which the coordination spheres of the Li centres are completed by THF molecules, i.e. {Li(THF)[μ3‐OC6H4(CH=CH−CH3)‐2]}4 (1). Compound 1 proved to be rather unreactive and unsuitable as a starting material for the introduction of the corresponding aryloxide ligands into the coordination sphere of molybdenum by salt metathesis. The latter did occur, however, when “POLi” was synthesised in the presence of 12‐crown‐4 and subsequently treated with molybdenyl chloride. This led to an unidentified aryloxide compound as well as to a hitherto unknown chlorooxomolybdate anion in the complexes [Li(12‐crown‐4)][MoO2Cl3(THF)] (2) and [{Li(12‐crown‐4)}2Cl][MoO2Cl3(THF)] (2′) with an octahedral coordination sphere at the molybdenum centre in each case. An Mo(PO) complex was finally isolated for the first time when MoO2(OtBu)2 was employed as a starting material and treated with “POLi” prepared in situ in the presence of the crown ether. This led to the isolation of [Li(12‐crown‐4)2][MoO2(PO)3] (3), which represents a rare example of a five‐coordinate dioxomolybdenum(VI) complex as well as being the first example among these complexes with a square‐pyramidal ligand arrangement. Comparison of 2 with 3 suggests that the low coordination number of the 14‐electron compound 3 originates from the bulkiness of the PO− ligands. The crystal structures of all three compounds 1−3 are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Plasma‐Enhanced CVD Synthesis and Structural Characterization of Ta2N3
Authors: Ganin Alexei Yu. , Kienle Lorenz , Vajenine Grigori V.
Published: July 2004

Microcrystalline tantalum nitride films were prepared on various substrates from TaCl5 precursor and nitrogen gas using the plasma‐enhanced chemical vapor deposition (PECVD) method. Syntheses carried out at 600−650 °C led to single‐phase samples of the tantalum nitride Ta2N3 with a defect fluorite‐type structure. The anion vacancies were found to order resulting in a 2 × 2 × 2 cubic superstructure of the C‐Ln2O3 type (space group Ia$\bar 3$
, Z = 16) with a = 9.8205(4) Å according to a Rietveld refinement of the X‐ray powder diffraction data. At higher deposition temperatures (650−700 °C) formation of highly textured orthorhombic Ta3N5 was observed. The samples were additionally studied by high‐resolution transmission electron microscopy (HRTEM) and selected‐area electron diffraction (SAED). The details of the new crystal structure for Ta2N3 as well as a possible nitrogen nonstoichiometry are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of Serine‐Linked Phosphatidylinositol Mannosides (PIMs)
Authors: Stadelmaier Andreas , Biskup Moritz B. , Schmidt Richard R.
Published: July 2004

The 6‐O‐allyl group of inositol mannoside (D)‐6 was used for the generation of O‐linked serine residues via a sequence of dihydroxylation, selective 3′′‐O‐protection, introduction of the 2′′‐amino group, deprotection, and oxidation of the 3′′‐position. Attachment of the phosphatidyl residue to 1‐O of the inositol moiety and complete deprotection furnished target molecules (D)‐1 and (D)‐2. Alternatively, instead of introduction of a 6‐O‐allyl group, 2′′,3′′‐dihydroxy propanylation of the 6‐O‐position of the inositol moiety using a silyl‐protected cyclic sulfate of glycerol was possible. Thus, target molecule (L)‐3 was obtained. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Convenient Synthesis of (−)‐Paroxetine
Authors: Czibula László , Nemes András , Sebök Ferenc , Szántay Csaba , Mák Marianna
Published: July 2004

A convenient synthesis of the antidepressant paroxetine starting from 1‐benzyl‐4‐piperidone (2) is reported. A stereoselective reduction resulted in cis‐piperidine‐3‐methanol [(+)‐6]. The reaction between cis‐piperidine‐3‐methanol mesylate (7) and sesamol led to benzyl‐protected trans‐paroxetine (9) through an inversion reaction of the stereogenic center at position 3. The latter compound was deprotected by hydrogenolysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Octadentate Ligands Containing 2,3‐Dihydroxybenzamide and 2,3‐Dihydroxyterephthalamide Coordinating Subunits on a Tetrapodal Amine Backbone for Chelation of Actinides
Authors: Xu Jide , Gorden Anne E. V. , Raymond Kenneth N.
Published: July 2004

The linear octadentate ligand 3,4,3‐LICAM(C) (2) is one of the most effective chelating agents for PuIV that is not acutely toxic; however, at physiological pH, due to the weak acidity of the catechol hydroxy groups and the large proton dependence of the complexation reaction, only three of the four catecholate subunits are coordinated to PuIV. To overcome this disadvantage, a new topological class of octadentate ligands based on tetrapodal amine backbones and 2,3‐dihydroxyterephthalamide (3) (TAM) binding units were designed and synthesized. The amide substituents provide a handle by which the functionality of the ligand can be readily modified, and this synthetic strategy and procedure can be extended to prepare a variety of new multidentate metal‐coordination and extraction agents. A streamlined synthesis for the terephthalamides, both symmetric and asymmetric, was recently reported. In this work, the synthetic details of their incorporation into octadentate systems for use as coordination or extraction agents for PuIV or other metals in the +4 oxidation state are described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Comparative Cyclotrimerisation of Enantiopure vic‐Bromo(trimethylstannyl)bicycloalkenes Derived from (+)‐Camphor, (+)‐Fenchocamphorone and (−)‐Epicamphor: Effect of the Bridgehead Methyl Group on the syn/anti Product Ratios
Authors: Fabris Fabrizio , Zambrini Laura , Rosso Enrico , De Lucchi Ottorino
Published: July 2004

The influence of the bridgehead methyl group on syn/anti diastereoselectivity in the cyclotrimerisation of polycyclic alkenes was investigated. To this end, three different enantiopure vic‐bromo(trimethylstannyl)‐substituted bicyclic olefins were prepared and used as probes. The effects of different copper(II) or ‐(I) salts were studied, and most dimeric intermediates were independently synthesised and characterised. Some indications of the mechanism of cyclotrimerisation were furnished by experiments aimed at determining the relative rates of dimerisation. The results gave useful indications of how to achieve highly effective syn‐cyclotrimerisation reactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Self‐Assembly of Octaaminoamido Derivatives of Resorcin[4]arene in Water − A “Cell‐Like” Submicron‐Scale Hydrogel Structure
Authors: Kazakova Ella K. , Morozova Julia E. , Prosvirkin Alexander V. , Pich Andrij Z. , Gubanov Eduard P. , Muslinkin Abdurakhim A. , Habicher Wolf D. , Konovalov Alexander I.
Published: July 2004

We have prepared four new octaaminoamide resorcin[4]arenes having hydrocarbon chains of different lengths (1, 2: R = CH3; 3, 4: R = C11H23) and different terminal groups (1, 3: NH2; 2, 4: NMe2). The surface tension and self‐assembly of aqueous solutions of 2−4 were studied and their critical micelle concentrations (CMC) were determined. At the water/air interface, compound 2 forms a multilayer structure, whereas compound 3 forms a bilayer and compound 4 a monolayer structure. In addition, we found that compound 3 has a second CMC (CMC2). A dynamic light scattering study indicated that, at a concentration of 0.1 wt% (i.e., > CMC2), 3 forms nanodimensional aggregates; increasing the concentration up to 1.2 wt% results in the formation of strong transparent gels. For hydrogels having 5 wt% of 3, SEM images demonstrated the formation of submicron‐scale “cell‐like” aggregates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Cyclic Vicinal Bis(tetraketone) and Structural Investigations of Formoins
Authors: Peter Matthias , Gleiter Rolf , Rominger Frank , Oeser Thomas
Published: July 2004

Investigations of simple formoins such as 2,5‐bis(1,1‐dimethyl‐2‐phenylethyl)‐2,4‐dihydroxyfuran‐3(2H)‐one (17), benzoylformoin (18), p‐toluoylformoin (19), pivaloylformoin (20), and the 2,4‐dihydroxy‐2,5‐bis(heterocycl‐2‐yl)furan‐3‐ones 21−23 (heterocycle = furan, thiophene, selenophene) by NMR spectroscopy in DMSO showed the dihydroxyfuranone skeleton and not an enediol structure. The formoin 17 was oxidized to the corresponding tetraketone 10. The intermolecular double benzoin condensation of 1,4‐bis(2,2dimethyl‐3,4‐dioxobutyl)benzene (27) affords, in low yield, the bis(formoin) 29, and this could be oxidized to provide 2,2,2′,2′,7,7,7′,7′‐octamethyl[8.8]paracyclophan‐3,3′,4,4′5,5′6,6′‐octaone (9). The molecular structures of 17 and 29, the monohydrate of 10 (30), and also the dihydrate of 9 (31) are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Stereoselective Synthesis of Enantiomerically Pure Piperidine Derivatives by N‐Galactosylation of Pyridones
Authors: Klegraf Ellen , Follmann Markus , Schollmeyer Dieter , Kunz Horst
Published: July 2004

Stereoselective desymmetrization of 4‐pyridone has been achieved through selective N‐galactosylation, activation of the N‐(galactosyl)pyridone by O‐silylation and immediate addition of Grignard compounds. Chiral piperidine derivatives, e.g. (S)‐(+)‐coniine and (5S,9S)‐(+)‐indolozidine 167B, were synthesised in enantiomerically pure form using these highly regio‐ and stereoselective reactions. After N‐galactosylation of 2‐pyridone and O‐silylation of the N‐galactosyl‐2‐pyridone, addition of a Grignard compound proceeded with high 1,4‐regioselectivity and complete diastereoselectivity, to furnish 4‐substituted 5,6‐dehydro‐2‐piperidones. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
pH Effects on Ethanolysis of Some Arenediazonium Ions: Evidence for Homolytic Dediazoniation Proceeding through Formation of Transient Diazo Ethers
Authors: Pazo‐Llorente Roman , Bravo‐Diaz Carlos , Gonzalez‐Romero Elisa
Published: July 2004

The effects of pH on the observed rate constants (kobsd.) and on the solvolytic dediazoniation product distributions of ethanolysis of 2‐, 3‐, and 4‐methylbenzenediazonium ions (2MBD, 3MBD, and 4MBD, respectively) were determined by a combination of spectrophotometric (UV/Vis) and chromatographic (HPLC) techniques. The variation of both kobsd. and product yields with pH follow S‐shaped curves with inflection points at pH ≈︁ 3.6, depending on solvent composition. With increasing pH, kobsd. values increase by factors of up to about 4 (2MBD), about 3 (3MBD), and about 50 (4MBD) with respect to the kobsd. values at low pH. HPLC analyses of the reaction mixtures show that only heterolytic products are obtained at low pH, indicating that solvolytic dediazoniation takes place through an ionic mechanism, but an increase in pH favors homolytic dediazoniation, with quantitative conversion into the reduction product toluene being obtained at pH ⩾ 6 (4MBD), indicating that a turnover from the heterolytic to the homolytic mechanisms is taking place under experimental conditions under which insignificant amounts of EtO− or OH− should be present in solution. The obtained S‐shaped profiles suggest that the initiation process of the homolytic pathway is the result of the formation of a highly unstable transient diazo ether complex and not by direct electron transfer from the solvent (EtOH) to the arenediazonium ions as is currently believed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Short Synthesis of New 23‐Vinyl Steroid Derivatives from Sapogenins by the Action of 9‐BBN on Vinylogous Esters
Authors: Sandoval‐Ramírez Jesús , Meza‐Reyes Socorro , del Rio Rosa E. , Vazques Fabiola Reyes‐ , Santillán Rosa Luisa , Achab Said , Bohé Luis
Published: July 2004

Some new 16β‐acetoxy‐22,26‐epoxy‐23‐vinylcholest‐22‐ene steroid derivatives have been synthesized from sapogenins via a two‐step sequence involving the reduction of a vinylogous ester moiety by 9‐BBN, a reaction with few precedents and for which a coherent mechanistic interpretation has not been given before now. Some mechanistic insight into this reaction was gained from NMR spectroscopic evidence. A plausible general mechanistic interpretation of the action of 9‐BBN on vinylogous esters is proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
An Original Approach to the Synthesis of Phosphorus‐Carbon Heterocycles − The 3‐Oxo‐2,3‐dihydro‐1,3‐oxaphospholes
Authors: Virieux David , Ciptadi Ciptadi , Bekro Yves‐Alain , Cristau Henri‐Jean
Published: July 2004

The synthesis of new highly functionalized phosphorus heterocycles, the 3‐oxo‐2,3‐dihydro‐1,3‐oxaphospholes, was achieved by a cyclization reaction involving malonic enolates as 1,3‐O,C‐dinucleophiles and phosphorus compounds, such as (chloromethyl)phosphinic chlorides or alkyl (chloromethyl)phosphonochloridates, as 1,2‐dielectrophiles. Owing to the structural restriction that results from the cyclic structure, the 1H NMR spectra reveal extreme values of 2JP,H coupling constants that are sensitive to the HCPO dihedral angle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Iodinated Indole Alkaloids From Plakortis simplex − New Plakohypaphorines and an Evaluation of Their Antihistamine Activity
Authors: Borrelli Francesca , Campagnuolo Claudio , Capasso Raffaele , Fattorusso Ernesto , Taglialatela‐Scafati Orazio
Published: July 2004

Three new iodinated tryptophan derivatives, plakohypaphorines D−F (4−6), have been isolated from the Caribbean sponge Plakortis simplex. Their structures have been determined by applying spectroscopic methods and microwave‐assisted selective dehalogenation. Compound 5 is the first naturally occurring triiodinated indole, while compound 6 is a unique metabolite because it possesses both chlorine and iodine atoms on the indole nucleus. We have evaluated the antihistamine activity of the whole series of plakohypaphorines A−F, but only the diiodinated analogues proved to be active: they display a specific antagonism of the noncompetitive type. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Synthesis and Reactivity of Group 4 Zwitterionic Complexes of the Type Mt+CH2AlCl3−: One‐Component Stereoselective Polymerization and Oligomerization Catalysts for Olefins and Acetylenes
Authors: Eisch John J. , Otieno Peter O.
Published: July 2004

A reinvestigation of the interaction of TiCl4 with 2 equiv. of Me3Al in toluene between −78 °C and 25 °C over 24 h has now established that the ultimate black product obtained is an associated zwitterion of the type [Ti+−CH2−AlCl3−]n, supported by multinuclear NMR spectroscopy and mass spectrometric and gasometric analyses of the gases evolved (CH4, H2) upon its protolysis. Chemical reactions of the zwitterion have corroborated specific aspects of its proposed structure: 1) its methylene character, by its transformation of benzophenone into 1,1‐diphenylethylene; 2) its divalent titanium content, by the substantial reductive dimerization of benzophenone to tetraphenylethylene, and 3) its Lewis acidic Ti center, by its catalytic isomerization of trans‐stilbene oxide to 1,1‐diphenylacetaldehyde. Similar individual reactions of ZrCl4 or HfCl4 with Me3Al have led to the analogous zwitterions [Zr+−CH2−AlCl3−]n and [Hf+−CH2−AlCl3−]n, respectively. These zwitterions of Ti, Zr and Hf have been proven to be capable of the cyclotrimerization and/or polymerization of acetylenes with varying facility, as evidenced by their catalytic action on 1‐hexyne, phenylacetylene, di‐n‐butylacetylene, and diphenylacetylene. Furthermore, all three zwitterions were able to polymerize ethylene, without any added cocatalyst, with an activity following the order Zr > Ti > Hf. The Ti and Zr zwitterions effected the stereoselective polymerization of propylene to yield 50% of isotactic polymer, and all three catalysts induced the polymerization of 1‐hexene to yield 85% (Zr, Hf) or 100% (Ti) of isotactic polymer. These oligomerizations and stereoselective polymerizations of acetylenes and olefins can be rationalized through a model for the active site resembling a three‐membered metallacyclopropa(e)nium ion intermediate formed from the attack of the Group 4 metal zwitterion on the unsaturated hydrocarbon. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
C‐Glycosidic UDP‐GlcNAc Analogues as Inhibitors of UDP‐GlcNAc 2‐Epimerase
Authors: Stolz Florian , Blume Astrid , Hinderlich Stephan , Reutter Werner , Schmidt Richard R.
Published: July 2004

The first step in the biosynthesis of neuraminic acid, the “epimerisation” of UDP‐GlcNAc to ManNAc, is catalyzed by UDP‐GlcNAc 2‐epimerase. In this paper we report the synthesis of the C‐glycosidic UDP‐GlcNAc analogues 1−5 as substrate‐based inhibitors of this enzyme. The focus is on the optimal distance and geometry of the connection between the sugar and the UDP‐moiety, which are both important for recognition by UDP‐GlcNAc 2‐epimerase. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Enantiocontrolled Synthesis of 3‐Pyrrolines from α‐Amino Allenes
Authors: Horváth Attila , Benner Jessica , Bäckvall Jan‐E.
Published: July 2004

Cyclization of α‐amino allenes in the presence of N‐bromosuccinimide afforded pyrrolines in good yields. The products were obtained with high enantiomeric excesses when optically active allenes were used as substrates. The synthesis of a 2,5‐dehydroprolinol derivative is also presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Highly Functionalised Cyclobutanols by Samarium(II) Iodide Induced Radical Cyclisations of Carbohydrate‐Derived Unsaturated Ketones
Authors: Williams D. Bradley G. , Blann Kevin
Published: July 2004

Certain carbohydrates have been found to be excellent precursors for the samarium diiodide‐mediated 4‐exo‐trig cyclisation reaction of their keto‐olefin derivatives, which were readily prepared in a few easy steps. The cyclisation was found to be stereoselective, affording cis products, the diastereoselective excesses of which were influenced by the nature of the protecting group employed at C5−O of the furanose sugar. The major chiral cyclobutane product of the cyclisation step was converted into an advanced intermediate for the synthesis of a nucleoside anti‐viral analogue. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The First Enantioselective Halo Aldol Reaction of Ethyl Propiolate and Aldehydes
Authors: Chen Dianjun , Timmons Cody , Liu Junying , Headley Allan , Li Guigen
Published: July 2004

The first enantioselective halo aldol reaction of ethyl propiolate with aldehydes has been established by using Jacobsen’s chiral cyclohexylsalen ligand. The reaction was conducted at −20 °C in dichloromethane with Et2AlI as the source of halogen and Lewis acid promoter. Excellent geometric selectivity (only the Z isomer) has been achieved for all 14 examples examined. The reaction works well with aromatic aldehydes; it also works with aliphatic aldehydes and α,β‐unsaturated aldehydes, albeit with diminished yields and ee. This method provides the first enantioselective synthesis of β‐iodo Morita−Baylis−Hillman (MBH) esters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
TMSCl‐Mediated Catalytic Carbocupration of Alkynoates: An Unprecedented and Remarkable Effect of Catalyst Loading on Highly Selective Stereochemical Induction via a TMS‐Allenoate Intermediate
Authors: Jennings Michael P. , Sawant Kailas B.
Published: July 2004

The TMSCl‐mediated catalytic carbocupration of alkynoates has been investigated. It has been shown that catalyst loadings as low as 30 mol% readily allow for high yields and diastereoselectivities for a series of Grignard reagents. In addition, an unprecedented and remarkable effect of catalyst loading on stereochemical induction has been observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Allylsilanes in Organic Synthesis − Recent Developments (Eur. J. Org. Chem. 15/2004)
Authors: Chabaud Laurent , James Philippe , Landais Yannick
Published: July 2004

The cover picture shows the “Dune of Pyla”, the highest sand dune in Europe (105 m high, 2.7 km long and 500 m wide). It is situated 70 km away from Bordeaux, where part of the research described in the Microreview by Landais et al. on p. 3173 ff. was performed. The dune is composed of 60 million m3 of sand (silicates). Silicon is the second most abundant element inside the earth crust [O2 (46%), Si (28%), Al (8%)] and is essentially present in nature as its oxidized form (SiO2). Synthetic organosilicon compounds, and more particularly allylsilanes, are very common and useful organometallic intermediates for organic synthesis. Such synthons are of economical importance due to the abundance of silicon, and are of environmental concern due to the low toxicity of organosilicon by‐products.
Genetic and Epigenetic screening for gene alterations of the chromatin‐remodeling factor, SMARCA4/BRG1, in lung tumors
Authors: Medina Pedro P. , Carretero Julian , Fraga Mario F. , Esteller Manel , Sidransky David , Sanchez‐Cespedes Montserrat
Published: July 2004

The SMARCA4/BRG1 gene product is a component of the SWI‐SNF chromatin‐remodeling complex and regulates gene expression by disrupting histone‐DNA contacts in an ATP‐dependent manner. Inactivating mutations of the SMARCA4 gene, on chromosome arm 19p, are present in several human cancer cell lines, including cell lines derived from lung cancers. Interestingly, loss of heterozygosity (LOH) at 19p and absence of the SMARCA4 protein have been reported in lung tumors. To evaluate further the possible contribution of SMARCA4 gene inactivation to lung carcinogenesis, we performed a complete analysis of the SMARCA4 gene to search for (a) point mutations in all 35 coding exons, including an existing splicing variant and the intron–exon boundaries, and (b) abrogation of gene expression through promoter hypermethylation by using the methylation‐specific polymerase chain reaction (MSP) assay. We selected genomic DNA from 20 lung primary tumors with LOH on 19p for the screening of point mutations and 10 lung cancer cell lines and 52 lung primary tumors for the MSP analysis. Through our mutational screening, we identified an in‐frame and germ‐line insertion of 24 bp in exon 4 whose biological relevance is unknown. This variant was not detected in the germ line of the 62 additional individuals analyzed, indicating it is not a common polymorphism. Moreover, two missense alterations were identified in the tumors of 2 patients, a somatic Gly1160Arg mutation and a Ser1176Cys mutation. Neither was present in the germ line of the 51 additional lung cancer individuals tested. Because these mutations lead to substitution of highly conserved amino acids, they may affect the ATPase function of the protein. Finally, no promoter hypermethylation was observed in any lung primary tumor or cancer cell line, indicating that this is not a major mechanism for SMARCA4 inactivation during lung carcinogenesis. In conclusion, our data revealed that somatic point mutations of the SMARCA4 gene are present in a small subset of lung tumors, although mutations affecting the ATPase domain may be a hot‐spot for SMARCA4 gene inactivation. We cannot rule out that other mechanisms, such as complete or partial deletions of the SMARCA4 gene, are contributing to the loss of the SMARCA4 protein in lung cancer. © 2004 Wiley‐Liss, Inc.