bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synthesis of 3‐alkyl‐ and 3‐aryl‐β‐lactams from zinc enolates and imines
Authors: van Maanen Hendrik L. , Kleijn Henk , Jastrzebski Johann T. B. H. , van Koten Gerard 
Published: September 2010

AbstractChlorozinc enolates of (hetero)aryl‐, alkyl‐ and silyl‐substituted acetates were reacted with imines and α‐diimines. The zinc‐mediated reaction of (hetero)aryl‐substituted acetates with imines afforded trans‐β‐lactams in good yields and with excellent selectivity. Zinc enolates of non‐functionalized alkanoates yielded the corresponding 3‐alkyl‐β‐lactams (predominantly trans) in moderate yields. Bulky substituents increase the rate and enhance the cis‐trans selectivity of the reaction. Methyl 2‐(trimethylsilyl)acetate does not afford 3‐(trimethylsilyl)‐β‐lactams via the zinc‐mediated reaction with imines, but N‐(trimethylsilyl)‐β‐amino esters, which are formed via an intramolecular silyl shift. The desilylated β‐amino esters were obtained from the zinc enolate of methyl acetate, albeit in moderate conversion, and careful control of the reaction conditions was necessary to avoid side‐reactions. The substituent effects are discussed in terms of pre‐equilibria involving the enolate and six‐membered cyclic transition states.
Amination of dinitrobenzenes with liquid methylamine/potassium‐permanganate
Authors: Woźniak Marian , Grzegożek Maria , Roszkiewicz Witold , Szpakiewicz Barbara 
Published: September 2010

Abstract1,3‐Dinitrobenzene (1a) and some simple monosubstituted derivatives (1b–g) were aminated with a liquid methylamine solution of potassium permanganate (LMA/PP) to give the corresponding mono‐ and bis(methylamino)‐substituted compounds (3a‐e and 4a). 1,2‐Dinitrobenzene (1i) was aminated with LMA/PP to give 2‐(methylamino)‐1‐nitrobenzene (3f) in high yield. The intermediacy of 4‐(methylamino) σ‐adducts of 1,3‐dinitrobenzene (2a), 2‐chloro‐ (2b) and 2‐amino‐1,3‐dinitrobenzene (2c) was established by 1H‐NMR spectroscopy. Quantum‐chemical calculations for the dinitrobenzenes suggest that, in general, the experimentally observed regioselectivity of the methylamination is satisfactorily described by frontier molecular orbital (FMO) interaction of the reagents.
Metallation and functionalization of N‐vinylpyrrole
Authors: Mal'Kina A. G. , Tarasova O. A. , Trofimov B. A. , Verkruijsse H. D. , van der Kerk A. C. H. T. M. , Brandsma L. 
Published: September 2010

AbstractMetallation of N‐vinylpyrrole under presumed kinetic conditions, using n‐butyllithium in THF/hexane mixtures, n‐butyllithium/N,N,N′,N′‐tetramethylethanediamine in hexane, or n‐butyllithium/potassium tert‐butoxide (1:1 molar ratio) in THF/hexane mixtures gives almost equal amounts of derivatives metallated at the α‐vinyl or 2‐pyrrole position. In the presence of 7–10 mol% diisopropylamine the α‐vinyl‐lithiated compound is transformed relatively slowly into the pyrrole‐lithiated derivative at ∼ +30°c. The combined use of catalytic amounts of diisopropylamine and equivalent amounts of n‐butyllithium and potassium tert‐butoxide gives rise to a fast and almost complete conversion into the pyrrole‐metallated derivative at temperatures in the range ‐60 to –80°c. A number of 2‐substituted N‐vinylpyrroles have been obtained in good yields by reaction with various electrophilic reagents, in most cases preceded by the addition of anhydrous lithium bromide. N‐Deprotection is successful only in the case of N‐vinyl‐2‐pyrrole‐carboxaldehyde.
Redox behavior of trimanganese tetraoxide catalysts
Authors: Weimin Wang , Yongnian Yang , Jiayu Zhang 
Published: September 2010

AbstractNew methods were used to prepare a nearly stoichiometric Mn3O4 catalyst. The redox behavior of two kinds of Mn3O4 (i.e. the non‐ and nearly stoichiometric Mn3O4) were compared. The relations between the IR parameters, Mn/O stoichiometry and redox properties of Mn3O4 were established. It was found that the Mn/O stoichiometry but not IR parameters was closely related to the redox behavior of the compounds.
Transformations of the tetracyclic skeleton of eudistomins by neighboring‐group participation in the Mitsunobu reaction
Authors: van Maarseveen Jan H. , Oberyé Elna H. H. , Bolster Marjon B. , Scheeren Hans W. , Kruse Chris G. 
Published: September 2010

AbstractMitsunobu reaction mediated introduction of nitrogen nucleophiles into trans 1‐hydroxy eudistomins afforded in high yields rearranged products instead of the anticipated cis eudistomins due to neighboring group participations. Transannular interaction in the 6,5,6,7‐membered tetracyclic ring system of the sulfur atom in the 1,6,2‐oxathiazepine ring, to give a thiiranium ion containing intermediate, was followed by intermolecular attack of the present nucleophiles to give a 6,5,6,6‐membered tetracyclic ring system, now with a 1,5,2‐oxathiazine ring. Substitution of the hydroxyl group in a trans 1‐hydroxy dethia carba eudistomin derivative (i.e. with a 1,2‐oxazepine ring) also gave rearranged products due to transannular interaction from the bridgehead nitrogen atom, to give via an aziridinium ion intermediate, products with a 6,5,7,6‐membered tetracyclic ring system containing an 1,2‐oxazine ring.
Chiral basket‐shaped host compounds derived from diphenylglycoluril
Authors: Coolen H. K. A. C. , Engelkamp H. , Reek J. N. H. , Priem A. H. , Nolte R. J. M. , van Leeuwen P. W. N. M. 
Published: September 2010

AbstractThe design and synthesis of two novel chiral receptors derived from diphenylglycoluril are described. The chirality in these molecules is due to the unsymmetrical positioning of amino functions in the crown ether rings with respect to the diphenylglycoluril subunit.
Chemical properties of butadienyl anions in the gas‐phase
Authors: de Visser Sam P. , de Koning Leo J. , van der Hart Wim J. , Nibbering Nico M. M. 
Published: September 2010

AbstractProton abstraction from 1,3‐butadiene by strong anionic bases in a Fourier‐transform ion‐cyclotron resonance mass spectrometer at relatively low pressure, yields an isomeric mixture of 1‐ and 2‐butadienyl anions. The gas‐phase acidity, ΔG°acid, of 1,3‐butadiene, associated with proton abstraction from the 2‐position, leading to 2‐butadienyl anions, is determined as 1627 ± 2 kJ/mol. 1‐Butadienyl anions, formed by proton abstraction from the 1‐position in 1,3‐butadiene, are found to be about 10 kJ/mol less stable than 2‐butadienyl anions. This stability difference is confirmed by high‐level ab‐initio calculations, which predict a planar, charge‐localized structure for the 1‐butadienyl anions, in which the butadiene π‐system is still intact. Additional stabilization of the 2‐butadienyl anion is realized by a 100° rotation of the central CC bond, which breaks up the butadiene π‐system in order to achieve allylic charge delocalization leading to a structure with two nearly orthogonal π‐systems. The isomeric 1‐ and 2‐butadienyl anions can be distinguished and identified conveniently and unambiguously by a probe reaction with nitrous oxide, which clearly reveals the distinct chemical nature of the two isomeric butadienyl anions.
Intramolecular hydrogen bonding in acylated 2,2′‐bipyridine‐3,3′‐diamines
Authors: Palmans A. R. A. , Vekemans J. A. J. M. , Meijer E. W. 
Published: September 2010

AbstractVarious di‐ and monoacylated 2,2′‐bipyridine‐3,3′‐diamines (amides 1a‐f, 8, 9, ureas 1g‐h, 8b and acylureas 1i‐j) have been synthesized and characterized. All molecules show strong intramolecular hydrogen bonding between the acyl NH of one ring and the pyridine N‐1 of the other (and vice versa), as is deduced from the low field 1H NMR resonances of the acyl NH protons, which range from δ 12.6 to 15.0 ppm in CDCl3. The nature of the secondary structure of the (di)acylated 2,2′‐bipyridine‐3,3′‐diamines has been investigated using a variety of techniques including variable‐temperature 1H NMR and CD spectroscopy.
Peptides from chiral Cαα‐disubstituted glycines. On the helical screw sense of isovaline peptides
Authors: Crisma M. , Valle G. , Pantano M. , Formaggio F. , Bonora G. M. , Toniolo C. , Kamphuis J. 
Published: September 2010

AbstractThe preferred conformation of three Nα‐acetylated Aib/Iva host/guest pentapeptide esters and their Nα‐benzyloxycarbonylated synthetic precursors, prepared by solution methods and fully characterized, were examined in chloroform solution using FT‐IR absorption and 1H‐NMR and in the crystal state by X‐ray diffraction. All these peptides are folded in a 310‐helix structure, irrespective of the experimental conditions used in the conformational analysis. In the crystal state the screw sense preference of the helical structure that is formed seems to be governed by the position of the single Iva residue in the peptide main chain, the ethyl side‐chain disposition, and the nature of the Nα‐blocking group.
Gilvocarcins
Authors: Hua Duy H. , Saha Shankar 
Published: September 2010

AbstractSyntheses of the aglycones of gilvocarcins, gilvocarcin‐related C‐glycosides, and (+)‐gilvocarcin M are described. Variety of methodologies have been reported for the construction of the aglycones of gilvocarcins including Meerwein and Diels‐Alder reactions, nucleophilic aromatic substitution, palladium‐catalyzed coupling, Suzuki biaryl coupling, Dotz carbene chromium benzannulation, conjugate addition to naphthoquinone ketals, and Pechmann condensation. In the syntheses of gilvocarcin‐related C‐glycosides, only those reactions involving palladium‐mediated coupling, Lewis‐acid‐mediated condensation, cuprate reagents, and reductive aromatization of quinol ketals were surveyed.
The analysis of very small samples of repeated measurements I: An adjusted sandwich estimator
Authors: Skene Simon S. , Kenward Michael G. 
Published: September 2010

AbstractThe statistical analysis of repeated measures or longitudinal data always requires the accommodation of the covariance structure of the repeated measurements at some stage in the analysis. The general linear mixed model is often used for such analyses, and allows for the specification of both a mean model and a covariance structure. Often the covariance structure itself is not of direct interest, but only a means to producing valid inferences about the response. Existing methods of analysis are often inadequate where the sample size is small. More precisely, statistical measures of goodness of fit are not necessarily the right measure of the appropriateness of a covariance structure and inferences based on conventional Wald‐type procedures do not approximate sufficiently well their nominal properties when data are unbalanced or incomplete. This is shown to be the case when adopting the Kenward–Roger adjustment where the sample size is very small. A generalization of an approach to Wald tests using a bias‐adjusted empirical sandwich estimator for the covariance matrix of the fixed effects parameters from generalized estimating equations is developed for Gaussian repeated measurements. This is shown to attain the correct test size but has very low power. Copyright © 2010 John Wiley & Sons, Ltd.
Seiltausch unter Verkehr an der Rheinbrücke Flehe
Authors: Gurtmann Stefan , Hamme Markus , Marzahn Gero , Sieberth Sven 
Published: September 2010

AbstractEs wird über den Seiltausch an der Rheinbrücke Flehe berichtet. Auf Grund umfangreicher Schäden an der Seilabspannung mussten neun Tragseile der Rheinbrücke Flehe im Zuge der Bundesautobahn A46 getauscht werden. Wegen der sehr hohen täglichen Verkehrsbelastung waren Eingriffe in den laufenden Verkehr weitgehend zu verhindern, so dass der Seiltausch bei laufendem Verkehr durchgeführt wurde. Diese komplexe Aufgabe stellte höchste Anforderungen an alle Beteiligten, wurde aber letztlich mit einem erfolgreichen Abschluss der Maßnahme belohnt.Replacing stay‐cables of the Rhine River crossing Rheinbrücke Flehe, Germany. The paper reports on the replacement works of nine stay cables of the Rhine River Bridge Flehe, a cable‐stayed bridge south of Düsseldorf, Germany. Due to a long service life the stay cables showed some signs of damage and needed to be repaired. Because of foremost damages of nine cables especially open fractures of single wires, they had to be replaced instead. The replacement not only required enormous structural and technical skills, but also engagement of all involved in. This was mainly due to the necessity of keeping the traffic uninterrupted and to prevent any closures of lanes. This administrational demand was successfully mastered. Besides slightly narrowed lanes widths, the bridge's traffic area remained unaffected by this replacement work with traffic able to continue flowing throughout the project.
Minitab
Authors: Alin Aylin 
Published: September 2010

AbstractStatistical software is an inevitable part of statistical analyses. Minitab is a well‐known statistical software, which was developed in 1972 by three university instructors as a teaching tool for introductory statistics courses. But, today it has strengthened its position not only in introductory statistics courses but also in advance statistical courses at universities, and even in government, business, and industry. In this article, some properties of the software and some of the improvements made by its latest version are presented and its importance as a teaching tool has been emphasized. WIREs Comp Stat 2010 2 723–727 DOI: 10.1002/wics.113This article is categorized under:

Software for Computational Statistics > Software/Statistical Software
A Heterotetranuclear Metal Complex {Ni2Na2} with Azido Bridges
Authors: Ge Cheng‐Min , Zhang Shu‐Hua , Feng Chao , Wang Yin‐Guang , Li Wei 
Published: September 2010

AbstractThe reaction of Ni(ClO4)2·6H2O with 3‐ethoxy‐2‐hydroxybenzaldehyde (Hemp), methylamine, and NaN3 in DMF solution, under solvothermal conditions, leads to the formation of the heterotetrametallic cluster [Ni2Na2(μ1,1,1‐N3)2(emimp)4(DMF)2] (I) (emimp = 2‐ethoxy‐6‐formyl‐phenolate anion, DMF = N,N‐dimethyl‐formamide). Compound I displays dominant ferromagnetic interactions through μ1,1,1‐N3 bridging mode.
Syntheses, Structures, and Luminescent Properties of Two Novel Coordination Polymers with Dipicolinate and Diimidazole Ligands
Authors: Liu Tong‐Fei , Wu Wan‐Fei , Zhang Wei‐Guo , Cui Guang‐Hua 
Published: September 2010

AbstractTwo novel coordination polymers, [Zn(dpc)(bmix)0.5]n (1), [Pb(dpc)(bmix)0.5]n (2), [dpc = dipicolinate, bmix = 1,4‐bis(2‐methylimidazole‐1‐ylmethyl)benzene], were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, TGA, and X‐ray single crystal diffraction. In both complexes, the dipicolinate and bmix ligands act as spacers to link metal ions to give a 2D corrugated (6,3) network of 1 and a 3D microporous framework of 2, respectively. The difference in the architectures is due to a diverging coordination mode of the carboxylate function. Furthermore, solid state fluorescence properties of the two complexes were investigated at room temperature.
PERIODIC SOLUTIONS OF SINGULAR DIFFERENTIAL EQUATIONS WITH SIGN-CHANGING POTENTIAL
Authors: CHU JIFENG , ZHANG ZIHENG 
Published: September 2010

AbstractIn this paper we study the existence of positive periodic solutions to second-order singular differential equations with the sign-changing potential. Both the repulsive case and the attractive case are studied. The proof is based on Schauder’s fixed point theorem. Recent results in the literature are generalized and significantly improved.
PRONORMALITY IN GENERALIZEDFC-GROUPS
Authors: ROMANO E. , VINCENZI G. 
Published: September 2010

AbstractWe extend some results known forFC-groups to the classFC*of generalizedFC-groups introduced in de Giovanniet al.[‘Groups with restricted conjugacy classes’,Serdica Math. J.28(3) (2002), 241–254]. The main theorems pertain to the join of pronormal subgroups. The relevant role that the Wielandt subgroup plays in anFC*-group is pointed out.
Effects of bite size and duration of oral processing on retro-nasal aroma release – features contributing to meal termination
Authors: Ruijschop Rianne M. A. J. , Zijlstra Nicolien , Boelrijk Alexandra E. M. , Dijkstra Annereinou , Burgering Maurits J. M. , Graaf Cees de , Westerterp-Plantenga Margriet S. 
Published: September 2010

The brain response to a retro-nasally sensed food odour signals the perception of food and it is suggested to be related to satiation. It is hypothesised that consuming food either in multiple small bite sizes or with a longer durations of oral processing may evoke substantial oral processing per gram consumed and an increase in transit time in the oral cavity. This is expected to result in a higher cumulative retro-nasal aroma stimulation, which in turn may lead to increased feelings of satiation and decreased food intake. Using real-time atmospheric pressure chemical ionisation-MS, in vivo retro-nasal aroma release was assessed for twenty-one young, healthy and normal-weight subjects consuming dark chocolate-flavoured custard. Subjects were exposed to both free or fixed bite size (5 and 15 g) and durations of oral processing before swallowing (3 and 9 s) in a cross-over design. For a fixed amount of dark chocolate-flavoured custard, consumption in multiple small bite sizes resulted in a significantly higher cumulative extent of retro-nasal aroma release per gram consumed compared with a smaller amount of large bite sizes. In addition, a longer duration of oral processing tended to result in a higher cumulative extent of retro-nasal aroma release per gram consumed compared with a short duration of oral processing. An interaction effect of bite size and duration of oral processing was not observed. In conclusion, decreasing bite size or increasing duration of oral processing led to a higher cumulative retro-nasal aroma stimulation per gram consumed. Hence, adapting bite size or duration of oral processing indicates that meal termination can be accelerated by increasing the extent of retro-nasal aroma release and, subsequently, the satiation.
Borderline personality disorder co-morbidity: relationship to the internalizing–externalizing structure of common mental disorders
Authors: Eaton N. R. , Krueger R. F. , Keyes K. M. , Skodol A. E. , Markon K. E. , Grant B. F. , Hasin D. S. 
Published: September 2010

BackgroundBorderline personality disorder (BPD) shows high levels of co-morbidity with an array of psychiatric disorders. The meaning and causes of this co-morbidity are not fully understood. Our objective was to investigate and clarify the complex co-morbidity of BPD by integrating it into the structure of common mental disorders.MethodWe conducted exploratory and confirmatory factor analyses on diagnostic interview data from a representative US population-based sample of 34 653 civilian, non-institutionalized individuals aged ⩾18 years. We modeled the structure of lifetime DSM-IV diagnoses of BPD and antisocial personality disorder (ASPD), major depressive disorder, dysthymic disorder, panic disorder with agoraphobia, social phobia, specific phobia, generalized anxiety disorder, post-traumatic stress disorder, alcohol dependence, nicotine dependence, marijuana dependence, and any other drug dependence.ResultsIn both women and men, the internalizing–externalizing structure of common mental disorders captured the co-morbidity among all disorders including BPD. Although BPD was unidimensional in terms of its symptoms, BPD as a disorder showed associations with both the distress subfactor of the internalizing dimension and the externalizing dimension.ConclusionsThe complex patterns of co-morbidity observed with BPD represent connections to other disorders at the level of latent internalizing and externalizing dimensions. BPD is meaningfully connected with liabilities shared with common mental disorders, and these liability dimensions provide a beneficial focus for understanding the co-morbidity, etiology and treatment of BPD.
Epigenetic and inflammatory marker profiles associated with depression in a community-based epidemiologic sample
Authors: Uddin M. , Koenen K. C. , Aiello A. E. , Wildman D. E. , de los Santos R. , Galea S. 
Published: September 2010

BackgroundRecent work suggests that epigenetic differences may be associated with psychiatric disorders. Here we investigate, in a community-based sample, whether methylation profiles distinguish between individuals with and without lifetime depression. We also investigate the physiologic consequences that may be associated with these profiles.MethodUsing whole blood-derived genomic DNA from a subset of participants in the Detroit Neighborhood Health Study (DNHS), we applied methylation microarrays to assess genome-wide methylation profiles for over 14 000 genes in 33 persons who reported a lifetime history of depression and 67 non-depressed adults. Bioinformatic functional analyses were performed on the genes uniquely methylated and unmethylated in each group, and inflammatory biomarkers [interleukin (IL)-6 and C-reactive protein (CRP)] were measured to investigate the possible functional significance of the methylation profiles observed.ResultsUniquely unmethylated gene sets distinguished between those withversuswithout lifetime depression. In particular, some processes (e.g. brain development, tryptophan metabolism) showed patterns suggestive of increased methylation among individuals with depression whereas others (e.g. lipoprotein) showed patterns suggestive of decreased methylation among individuals with depression. IL-6 and CRP levels were elevated among those with lifetime depression and, among those with depression only, IL-6 methylation showed an inverse correlation with circulating IL-6 and CRP.ConclusionsGenome-wide methylation profiles distinguish individuals withversuswithout lifetime depression in a community-based setting, and show coordinated signals with pathophysiological mechanisms previously implicated in the etiology of this disorder. Examining epigenetic mechanisms in concert with other dynamic markers of physiologic functioning should improve our understanding of the neurobiology of depression.
A comprehensive review and model of putative prodromal features of bipolar affective disorder
Authors: Howes O. D. , Lim S. , Theologos G. , Yung A. R. , Goodwin G. M. , McGuire P. 
Published: September 2010

BackgroundIdentifying prodromal features that predate the onset of bipolar disorder (BD) may enable the prevention of BD and aid early intervention. This review addresses two key questions: Is there a bipolar prodrome? And, if there is, what are its characteristic features?MethodA comprehensive search of databases (PubMed, Medline, EMBASE and PsycINFO) supplemented by hand searches was used to identify studies of symptoms preceding the onset of BD.ResultsFifty-nine studies were identified, of which 14 met inclusion criteria. Symptoms can predate the onset of BD by months to years and can be categorized as attenuated forms of BD symptoms, general symptoms common to a range of mental disorders, and personality traits, particularly cyclothymia. Two studies provided sufficient data to enable sensitivity and specificity to be calculated. Specificity of several of the features was high (>90%) but sensitivity was generally low (all <60%). We propose a model based on the findings in the studies reviewed to illustrate the potential trajectory to BD and the points at which it may be possible to intervene.ConclusionsClinical features preceding the onset of BD can be identified. However, conclusions about whether there is a distinct prodrome to BD are restricted by the limitations of current evidence. The high specificity of some features suggests they may be useful in clinical practice. Large-scale longitudinal studies are needed to validate these features and characterize their specificity and sensitivity in independent samples.