bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absolute Conformation Revisited: Experimental Approach
Authors: Ōki Michinori , Toyota Shinji 
Published: January 2004

AbstractWe propose that the term “absolute conformation” be used when one of the chiroptical properties is correlated with one of a pair of enantiomeric conformations. We present examples of compounds for which absolute conformations are known, as well as their syntheses, enantiomer resolution, and determination of absolute conformations, and discuss specifications of those conformations. The examples were selected from molecules for which one conformation is optically inactive but, by internal rotation about a C(sp3)−C(sp3) bond, optically active conformers are produced. There are some problems, which we discuss as Future Problems, that arise when conformations are taken into account, even though the classical treatment of stereochemistry is well established in such areas. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cyrmenins, Novel Antifungal Peptides Containing a Nitrogen‐Linked β‐Methoxyacrylate Pharmacophore: Isolation and Structural Elucidation
Authors: Leibold Thomas , Sasse Florenz , Reichenbach Hans , Höfle Gerhard 
Published: January 2004

AbstractThe novel antifungal metabolites cyrmenin A, B1, and B2 (1−3) were isolated from Archangium gephyra and Cystobacter armeniaca strains (myxobacteria). The cyrmenins are modified N‐acyldipeptide esters containing a didehydroalanine, a 3‐O‐methyl‐didehydroserine and a (2E,4Z)‐undecadienoic or ‐dodecadienoic acid residue. These compounds represent the first bacterial counterparts of strobilurins that are characterized by an α‐substituted β‐methoxyacrylate pharmacophore. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Dinuclear Metal Complexes Based on all‐cis‐2,4,6‐Triaminocyclohexane‐1,3,5‐triol as Catalysts for Cleavage of Phosphate Esters
Authors: Mancin Fabrizio , Rampazzo Enrico , Tecilla Paolo , Tonellato Umberto 
Published: January 2004

AbstractTwo dimetallic ligands 2 and 3 for transition metal ions were obtained by connecting two all‐cis‐2,4,6‐triamino‐cyclohexane‐1,3,5‐triol (TACI, 1) subunits via 1,3‐ or 1,4‐xylyl linkers. Their dimetallic CuII and ZnII complexes were investigated as catalysts for the cleavage of the phosphate diesters 2,4‐dinitrophenyl ethyl phosphate (DNPEP) and 2‐hydroxypropyl p‐nitrophenyl phosphate (HPNP) and the triester 2,4‐dinitrophenyl diethyl phosphate (DNPDEP). The results of a comparative kinetic study using the monometallic complexes of TACI as a reference indicate that the CuII complexes of 2 and 3 are virtually inert; this finding is ascribed to the formation of intra‐complex μ‐hydroxo bridges that prevent the required interactions with the substrate. On the other hand, the dimetallic ZnII complexes produce remarkable accelerations, particularly in the case of the HPNP transesterification. The dimetallic systems are more efficient than the TACI·ZnII complex in promoting the hydrolysis of HPNP at pH values close to neutrality (7.0−7.8). In this case, the effects of cooperativity between the two metal centers were highlighted in a detailed kinetic study; the catalytic efficiency seems to be related to the stronger binding of the substrate to the dimetallic ZnII complexes. Additionally, in this case, although to a much lesser extent than in the case of the CuII counterparts, the formation of μ‐hydroxo bridges apparently hampers the catalytic efficiency, as indicated also by the observation that the activity of the dimetallic complexes increases as the distance between the two metal centers increases, which, thus, thwarts the formation of intermetallic bridges. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Organometallics in Cyanine Chemistry − Synthesis, Reactivity and Photophysical Properties of some Heptamethine Merocyanine Dyes
Authors: Viteva Lilia , Gospodova Tzveta , Stefanovsky Yuri , Petrova Krasimira , Timtcheva Iliana , Mazières Marie‐Rose , Wolf Jean‐Gerard 
Published: January 2004

AbstractA one‐pot reaction between lithium reagents of ketones and pentamethine cyanine dyes affords a series of seven‐carbon merocyanines in good to excellent yields. In subsequent reactions with “soft” organolithium reagents they can be easily converted into anionic cyanine dyes, oxonols. The synthetic potential and limitations of this reaction are discussed. Absorption and fluorescence behavior of the studied merocyanines were found to depend on their substitution patterns and the solvent used. Based on the relationship between the absorption maxima and ET(30) (= solvent polarity parameter) constants, a different nature of the absorbing state in protic and non‐protic solvents can be assumed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Hydrostannylation of Propargylic Alcohols Using Mixed Tin Hydrides
Authors: Thiele Christina M. , Mitchell Terence N. 
Published: January 2004

AbstractThe hydrostannylation of a series of alkynols and propargylic ethers with mixed tin hydrides Bu2SnHCl and Bu2SnHBr has been studied. These highly reactive tin hydrides undergo radical chain reactions at low to ambient temperatures (−78 °C to 25 °C). Their higher Lewis acidity (in comparison with the most commonly used hydrostannylation reagent Bu3SnH) leads to much better regio‐ and stereoselectivities irrespective of the size and nature of the substituents in the propargylic position. Hydrostannylation of terminal propargylic alcohols and ethers gives almost solely (> 90 %) the products of anti‐addition; these are stabilized by intramolecular coordination. When non‐terminal propargylic alcohols are used, the isomerisation to the thermodynamically favoured syn‐addition product, which normally takes place in free radical hydrostannylations, can be prevented by choosing appropriate reaction conditions. Hydrostannylation of allyl propargyl ether shows that these reagents are highly chemoselective towards C−C triple bonds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Ring‐Expansion of MCPs in the Presence of DIAD or DEAD and Lewis Acids
Authors: Shao Li‐Xiong , Shi Min 
Published: January 2004

AbstractTreatment of methylenecyclopropanes (MCPs) with DIAD or DEAD in MeCN under mild conditions in the presence of Lewis acid Zr(OTf)4 gave the cyclobutanone ring‐expansion products in good to high yields based on the employed DIAD or DEAD. From a deuterium labeling experiment, the oxygen atom is derived from ambient water. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The C‐4 Configuration as a Probe for the Study of Glycosidation Reactions
Authors: Bülow Anne , Meyer Tine , Olszewski Tomasz Krzysztof , Bols Mikael 
Published: January 2004

AbstractThe difference in the electron‐withdrawing powers of axial and equatorial OBn was used as a probe to investigate the glycosidation reaction. The reactivity of perbenzylated glucosyl and galactosyl donors were compared under a range of glycosidation conditions that involved variations in catalyst, solvent, and glycosyl acceptor. Generally, the galactosyl donor had a reactivity four to five times higher than the glucosyl donor, which is in accord with the transition state having positive character. In certain cases, however, particularly when triflate was present, equal reactivity of glucosyl and galactosyl donors were found. The results are explained in terms of changes in the rate‐determining steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis and Biological Activity of Point‐Fluorinated Pheromone Analogues of Eldana saccharina
Authors: Itoh Toshiyuki , Kudo Kazutoshi , Yokota Kazuhisa , Tanaka Naoko , Hayase Shuichi , Renou Michel 
Published: January 2004

AbstractSubstitution of fluorine atoms on an organic molecule makes it possible to modify the molecular orbital and electron density of the surface without changing its molecular shape. Point‐fluorinated analogues of the sex pheromone of the male African sugarcane borer were synthesized in optically active forms and their pheromone activities were investigated using an EAG test. The EAG activity of these point‐fluorinated pheromone analogues indicates that the point of fluorination has a critical influence on the pheromone activity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Studies on the Origin of 1,5‐anti Induction in Boron‐Mediated Aldol Reactions
Authors: Stocker Bridget L. , Teesdale‐Spittle Paul , Hoberg John O. 
Published: January 2004

AbstractA model for the origin of selectivity in boron‐mediated 1,5‐anti‐aldols is presented. This model involves π‐stacking between the boron enolate and a remote aromatic ring. A short, facile method for the synthesis of the C‐12 to C‐22 segment of peloruside A and its 1,5‐anti‐aldol coupling using the proposed model is also presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Decelerating Effect of Alkynes in the Oxidative Addition of Phenyl Iodide to Palladium(0) Complexes in Palladium‐Catalyzed Multicomponent Reactions and Sonogashira Reactions
Authors: Amatore Christian , Bensalem Samia , Ghalem Said , Jutand Anny , Medjour Youcef 
Published: January 2004

AbstractThe oxidative addition of PhI to [Pd0(PPh3)4] in DMF is slower when performed in the presence of the terminal alkynes (PhC≡CH, EtO2C−C≡CH) that are reagents in palladiumcatalyzed Sonogashira or multicomponent reactions. The concentration of the reactive [Pd0(PPh3)2] complex decreases because of its partial coordination to the alkyne to form [(η2‐RC≡CH)Pd0(PPh3)2] (R = Ph, EtCO2), which is in equilibrium with [Pd0(PPh3)2]. The complex [(η2‐PhC≡CH)Pd0(PPh3)2] was found to be unreactive whereas [(η2‐EtO2C− C≡CH)Pd0(PPh3)2] was found to be the unique reactive complex at high concentrations of EtO2C−C≡CH. As has been reported for alkenes, terminal alkynes play an unexpected role because they interfere in the oxidative addition before their usual reactions in the carbopalladation and transmetallation steps that follow it. Decreasing the rate of the fast oxidative addition with PhI may promote the efficiency of the catalytic cycle by bringing its rate closer to that of the slower carbopalladation or transmetallation steps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The Three‐Component Reaction between Isatin, α‐Amino Acids, and Dipolarophiles
Authors: Rehn Stanley , Bergman Jan , Stensland Birgitta 
Published: January 2004

Abstract3‐Spiro[pyrrolidino‐oxindoles] were prepared in high yields from a three‐component reaction between isatin, an α‐amino acid, and a dipolarophile. BothN‐substituted andN‐unsubstituted α‐amino acids were used as the amine component. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
The essential oils composition of Phlomis herba‐venti L. leaves and ﬂowers of Iranian origin
Authors: Morteza‐Semnani Katayoun , Azadbakht Mohammad , Goodarzi Afsaneh 
Published: January 2004

AbstractThe composition of the essential oils obtained from the dried leaves and ﬂowers of Phlomis herba‐venti L. (Labiatae) was analysed by GC and GC–MS. The major constituents of the leaf essential oil were germacrene D (33.9%), hexadecanoic acid (12.9%) and α‐pinene (9.4%). The major constituents of the ﬂower essential oil were hexadecanoic acid (33.1%), 6,10,14‐trimethylpentadecan‐2‐one (16.2%), 3‐methyltetradecane (6.7%) and germacrene D (6.7%). Copyright © 2003 John Wiley & Sons, Ltd.
Volatile constituents of Malay rose apple [Syzygium malaccense (L.) Merr. & Perry]
Authors: Pino Jorge A. , Marbot Rolando , Rosado Arístides , Vázquez Carlos 
Published: January 2004

AbstractThe volatile constituents of Malay rose apple fruits [Syzygium malaccense (L.) Merr. & Perry] growing in Cuba were analysed by GC–MS and GC; 133 compounds were identiﬁed in the aroma concentrate, of which 2‐phenylethanol and its esters (2‐phenylethyl acetate, 2‐phenylethyl isopentanoate, 2‐phenylethyl benzoate and 2‐phenylethyl phenylacetate) were found to be the major constituents. By correlating odour thresholds with the concentrations of volatiles (odour unit values), the relative contribution of individual compounds in fruit aroma was assessed. The exotic aroma character of Malay rose apple is the interaction of rose (2‐phenylethanol and its esters) and herbaceous (1‐octen‐3‐ol) notes contributing to the complexity of the aroma. Copyright © 2003 John Wiley & Sons, Ltd.
Constituents of the essential oils of four micropropagated Solidago species
Authors: Kalemba Danuta , Thiem Barbara 
Published: January 2004

AbstractIn vitro shoot culture of four Solidago species, S.virgaurea L., S.canadensis L., S.gigantea Ait. and S.graminifolia (L.) Salisb. were established from aseptically germinated seedlings. Proliferated axillary shoots were multiplied rapidly on Murashige and Skoog's medium, supplemented with 9.3 µm kinetin and 11.4 µm indole‐3‐acetic acid. Rooted plantlets were transferred to the soil, then grown in the ﬁeld. Aerial parts were collected from clonal‐propagated Solidago species during the ﬂowering stage. The essential oils, obtained from air‐dried plant material by hydrodistillation, were studied by GC and GC–MS. Slight differences were found in the yield and composition of essential oils between the micropropagated plants and wild plants growing in natural sites. Copyright © 2003 John Wiley & Sons, Ltd.
Inﬂuence of transplanting time on essential oil yield and composition in Artemisia annua plants grown under the climatic conditions of sub‐tropical north India
Authors: Haider Flora , Dwivedi Premdutt , Singh Sarita , Naqvi Ali Arif , Bagchi Gurudas 
Published: January 2004

AbstractThe yield and composition of the essential oil obtained by hydrodistillation of inﬂorescences from different populations of Artemisia annua L. (Asteraceae), transplanted during different months, was analysed using a combination of GC and GC–MS. Oil yield was found to range from 0.5 to as high as 1.6% (w/v), in which 24 constituents were identiﬁed, representing 84.4–92.2% of the total oil. Camphor was identiﬁed as the most abundant component in all the samples examined, followed by 1,8‐cineole, except in June‐transplanted plants, where b‐caryophyllene was found to be the second most abundant compound. Camphor and 1,8‐cineole alone constituted 44.7–65% of the total oil. The percentage occurrence of rest of the compounds was found to vary in different populations. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of aroma‐active compounds of Abies nephrolepis (Khingan ﬁr) needles using aroma extract dilution analysis
Authors: Yu Eun Jeong , Kim Tae Hwan , Kim Kyoung Heon , Lee Hyong Joo 
Published: January 2004

AbstractVolatile components in the needles of Abies nephrolepis (Khingan ﬁr), a conifer native to Korea, were extracted by simultaneous distillation–extraction. Gas chromatography–mass spectrometry using two types of capillary column with different polarities (DB‐5MS and DB‐WAX) revealed that α‐pinene (23.2%) is the most abundant compound, followed by limonene (12.7%), bornyl acetate (9.9%) and β‐caryophyllene (10.8%). Aroma‐active compounds of A. nephrolepis were determined using gas chromatography–olfactometry by aroma extract dilution analysis. a‐Pinene showed the highest ﬂavour dilution factors, ranging from 38 to 39 with characteristic pine aroma. (Z)‐3‐Hexenal and γ‐terpinene were also identiﬁed as important aroma‐active compounds. Copyright © 2004 John Wiley & Sons, Ltd.
The persistence of neuropsychiatric symptoms in dementia: the Cache County Study
Authors: Steinberg Martin , Tschanz JoAnn T. , Corcoran Christopher , Steffens David C. , Norton Maria C. , Lyketsos Constantine G. , Breitner John C.S. 
Published: January 2004

AbstractObjectiveTo estimate the 18‐month persistence of neuropsychiatric symptoms in dementia in a population‐based sample, and to compare the severity of neuropsychiatric symptoms at baseline to the severity at 18‐month follow‐up.MethodsA population‐based sample of 329 residents of Cache County, Utah, diagnosed with dementia was rated on the Neuropsychiatric Inventory (NPI). Of the 204 participants with neuropsychiatric symptoms at baseline (defined as total NPI score >0), NPI data were obtained approximately 18 months later on 117 who were alive and available for follow‐up.ResultsEighty‐one percent of those with neuropsychiatric symptoms at baseline (defined as total NPI score>0) continued to have at least one symptom at follow‐up. Sixty‐seven percent of participants with a clinically significant total NPI score (defined as ≥;4) at baseline continued to have a clinically significant total NPI score at follow‐up. Among the ten neuropsychiatric domains assessed at baseline, delusions persisted in 65.5% of individuals, followed by depression (58.3%), and aberrant motor behavior (55.6%), while hallucinations and disinhibition persisted in only 25.0% and 11.1% respectively. In participants who were symptomatic at both baseline and follow‐up, the mean severity scores at the two observation points were comparable in all ten neuropsychiatric domains.ConclusionsNeuropsychiatric symptoms in dementia overall were highly persistent. Among those in whom symptoms did persist, symptom severity a year and a half later appeared to be comparable. Copyright © 2004 John Wiley & Sons, Ltd.
Poor mental and physical health differentially contributes to disability in hospitalized geriatric patients of different ages
Authors: Marengoni Alessandra , Agüero‐Torres Hedda , Cossi Stefania , Ghisla Maria Karin , De Martinis Monica , Leonardi Roberto , Fratiglioni Laura 
Published: January 2004

AbstractObjectiveTo evaluate the relationship between depressive symptoms, cognition and somatic diseases on functional status of geriatric patients at hospital discharge.MethodPatients 65+ years consecutively admitted to the acute care geriatric ward of the Internal Medicine Department I, Civil Hospital of Brescia, Italy, from February 1998 to December 2000 (n = 830) were examined. Functional disability was defined as need of physical assistance in at least one of the basic Activities of Daily Living (ADL). The Greenfield Index of Disease Severity (IDS) and the Geriatric Index of Comorbidity (GIC) were used to measure number and severity of diseases. The Mini‐Mental State Examination (MMSE) assessed cognitive status and the Geriatric Depression Scale (GDS) measured depressive symptoms.ResultsPrevalence of functional disability at discharge was 29.3% in the younger age group (65–74 years) and 55.2% in the older age group (75+ years). Using logistic regression models, older age, poorer cognitive status, and depressive symptoms were independently associated with functional disability in the younger and older age group, respectively. Additionally cognitive impairment and depressive symptoms showed an additive association with disability, especially in younger patients, while comorbidity was correlated with functional status only in the oldest old, in particular among those who were cognitively impaired.ConclusionFunctional disability after acute hospitalization is highly prevalent in geriatric patients. Depressive symptoms, comorbidity, and cognitive impairment often coexist, interact and are differentially associated with function depending on age. Considering that depressive symptoms are a modifiable problem, their detection in hospital settings may help clinicians in targeting subjects at high risk of functional disability. Copyright © 2004 John Wiley & Sons, Ltd.
Knowledge of Alzheimer's disease in four ethnic groups of older adults
Authors: Ayalon Liat , Areán Patricia A. 
Published: January 2004

AbstractObjectivesThe present study evaluated knowledge of Alzheimer's disease (AD) in four ethnic groups of older adults.MethodsNinety‐six Anglo, 37 Latino, 30 Asian, and 30 African American older adults completed a short survey about AD.ResultsResults indicated that Anglo older adults are significantly more knowledgeable about AD than African American, Asian, and Latino older adults. Level of education partially accounted for differences in knowledge of AD between Latino to Anglo older adults. After controlling for age, number of years of speaking English was associated with knowledge of AD in Asian older adults.ConclusionsThe results suggest that certain ethnic minority groups do not have sufficient information about AD, and this may explain the lack of AD service use by minorities. Extensive evaluation of barriers to knowledge of AD is needed in order to specifically target minority groups and educate them about AD and the importance of early intervention. Copyright © 2004 John Wiley & Sons, Ltd.
The 15‐item Geriatric Depression Scale (GDS‐15) detects changes in depressive symptoms after a major negative life event. The Leiden 85‐plus Study
Authors: Vinkers David J. , Gussekloo Jacobijn , Stek Max L. , Westendorp Rudi G. J. , van der Mast Roos C. 
Published: January 2004

AbstractBackgroundThe 15‐item Geriatric Depression Scale (GDS‐15) is a widely used screening instrument for depressive symptoms in the elderly, but its ability to detect alterations in depressive symptoms over time has not been established.ObjectiveTo assess the change of the GDS‐15 score after a major negative life event.MethodsWithin the Leiden 85‐plus Study, we prospectively followed a population‐based cohort of 599 subjects from 85 years onwards. The GDS‐15 was applied annually to participants with a Mini‐Mental State Examination (MMSE) score above 18 points. The change in GDS‐15 score of 32 subjects who had lost their partner during follow‐up was compared with a control group of 32 subjects who had not lost their partner, matched for age, sex, and initial GDS‐15 score.ResultsAt baseline, 241 subjects lived together with a partner. During a mean follow‐up of 3.2 years, 55 participants (23%) lost their partner. Of those, 32 subjects completed the GDS‐15 before and after the loss of their partner. All subjects reported the bereavement to be a major negative life event. The mean increase of the GDS‐15 score after the death of a partner was 1.2 points (paired t‐test, p = 0.013). This was significantly higher than the mean change of −0.06 points in the matched control group (independent t‐test, p = 0.032), and independent of sex, level of education, pre‐bereavement GDS‐15 score, and time period since the loss of a partner.ConclusionThis study shows that the GDS‐15 detects change in depressive symptoms after loss of a partner, a negative life event that is the most important risk factor for depression in the elderly. Therefore, it may be concluded that the GDS‐15 has the ability to measure longitudinal alterations in depressive symptomatology. Copyright © 2004 John Wiley & Sons, Ltd.