bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Characterization of Lanthanide(III) Bis(guanidinate) Derivatives and the Catalytic Activity of Methyllanthanide Bis(guanidinate) Complexes for the Polymerization of ϵ‐Caprolactone and Methyl Methacrylate
Authors: Luo Yunjie , Yao Yingming , Shen Qi , Yu Kaibei , Weng Linhong
Published: June 2004

The synthesis and structure of new lanthanide complexes with the guanidinate ligand [(Me3Si)2NC(NiPr)2−] are described. Reaction of a THF slurry of LnCl3 with a hexane solution of [(SiMe3)2NC(NiPr)2]Li (1) in a 1:2 molar ratio afforded the new soluble organolanthanide complexes [(SiMe3)2NC(NiPr)2]Ln(μ‐Cl)2Li(THF)2 [Ln = Yb (2), Nd (3)]. Alkylation of 2 and 3 with 2 equiv. of MeLi in hexane gave [(SiMe3)2NC(NiPr)2]Ln(μ‐Me)2Li(TMEDA) [Ln = Yb (4), Nd (5)] in good yield as crystalline solids. The molecular structures of 2 and 5 were determined by single‐crystal X‐ray analysis. The lanthanide ions in these complexes display a distorted pseudo‐octahedral coordination geometry. Complexes 4 and 5 exhibited extremely high activity for the ring‐opening polymerization of ϵ‐caprolactone to give high molecular weight polymers. Complex 5 also showed good catalytic activity for the syndiotactic polymerization of methyl methacrylate. (© Wiley‐VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2002)
The Effect of Phenyl Substituents on the Activity of Some Zirconocene Photoinitiators
Authors: Polo Eleonora , Barbieri Andrea , Traverso Orazio
Published: June 2004

In this paper we report the synthesis of several unbridged zirconocenes, 1a−c, 2 and 5, each bearing a phenyl substituent in the 2‐position of the cyclopentadienyl ring. We also report their photochemical behaviour and we compare the results with those obtained with the corresponding unsubstituted metallocenes 3a−c and 4. Study of their electronic spectra and EPR/spin trapping experiments showed photogeneration of ligand‐ and zirconium‐centred radicals, thus making these complexes suitable as photoinitiators for radical polymerisation processes. The substitution of the hydrogen atom in the 2‐position with a phenyl group had positive effects both on the absorption coefficients, improving the light absorption efficiency, and on the reaction yields of tert‐butyl acrylate polymerisation. These results can be explained in terms of the combined effects of greater persistence of the radical in solution and/or increased efficiency of the radical in initiating the polymerisation process. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Photochromic Properties of a Spirooxazine and a Spiropyran in Alcoholic Solutions of Zirconium and Aluminium Alkoxides: Influence of the Ethyl Acetoacetate Chelating Agent on the Optical Properties
Authors: Lafuma Aurélie , Chodorowski‐Kimmes Sandrine , Quinn Francis X. , Sanchez Clément
Published: June 2004

The photochromism of two spiro compounds, a spiropyran and a spirooxazine, dissolved in alcoholic solutions of metal alkoxides M(OR)n (M = Zr, Al) has been studied. In the case of the aluminium alkoxide Al(OsBu)3, special photochromic behaviour is observed characteristic of complexation between the coloured form of the dyes and the aluminium. This chemical interaction induces a considerable shift in the absorption spectra and a significant retardation rate in the dark. Addition of ethyl acetoacetate, a bidentate chelate of aluminium, leads to the disappearance of this particular photochromic behaviour. (© Wiley‐VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003)
Alkylzinc Complexes with Achiral and Chiral Monoanionic N,N,O Heteroscorpionate Ligands
Authors: Hegelmann Ina , Beck Alexander , Eichhorn Christian , Weibert Bernhard , Burzlaff Nicolai
Published: June 2004

The synthesis of the new chiral ligand (3,5‐di‐tertbutylpyrazol‐1‐yl)(3′,5′‐dimethylpyrazol‐1‐yl)aceticacid (bpaHtBu2,Me2) (4) has been achieved. Two different synthetic routes to its precursor 3,5‐di‐tert‐butyl‐1‐[(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methyl]‐1H‐pyrazole (bpmtBu2,Me2) (3) are reported. Deprotonation at the methylene group, followed by reaction with carbon dioxide, yielded a racemic mixture of 4. The chemical behaviour of bis(3,5‐di‐tert‐butylpyrazol‐1‐yl)acetic acid (bdtbpzaH) (2) and the new chiral N,N,O scorpionate ligand 4 involving their coordination to zinc ions was studied. [Zn(bpatBu2,Me2)Cl] (5) was formed from a mixture of ZnCl2, 4 and base. Reaction of bis(3,5‐di‐tert‐butylpyrazol‐1‐yl)acetic acid (bdtbpzaH) (2) with Zn(CH3)2 or Zn(CH2CH3)2 gave the alkylzinc complexes [Zn(bdtbpza)(CH3)] (6) and [Zn(bdtbpza)(CH2CH3)] (7). [Zn(bpatBu2,Me2)(CH3)] (8) was obtained from a synthesis analogous to that of 6 with 4. The further reactions of 6 and 8 with acetic acid resulted in the acetato complexes [Zn(OAc)(bdtbpza)] (9) and [Zn(OAc)(bpatBu2,Me2)] (10). The chiral methyl complex 8 may serve as a precursor for structural model complexes of the active sites of zinc enzymes, such as thermolysin or carboxypeptidase A. [Zn(bpatBu2,Me2)2] (11) was formed from a side reaction. Crystal structures of 4, 5, 8 and 11 were obtained; 5 crystallised as the dimer [Zn(bpatBu2,Me2)Cl]2; 11 presents an unusual zinc binding geometry. (© Wiley‐VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2003)
New Dinuclear Palladium Phosphane Complexes Stabilised by 8‐Thiotheophylline
Authors: Romerosa Antonio , López‐Magaña Carlos , Saoud Mustapha , Mañas Sonia
Published: June 2004

The new purine derivatives SS‐bis‐8‐(thio)‐theophylline (8‐BTTH2) and 8‐phenylthiotheophylline (8‐PhTTH), have been synthesised and characterised by elemental analysis, mass spectrometry and standard spectroscopic measurements. Reaction of 8‐BTTH2 with cis‐[PdCl2(PPh3)2] leads to the formation of the binuclear palladium complex [Pd(PPh3)(μ‐Cl)(8‐TT)]2 (8‐TTH2 = 8‐thiotheophylline) in which PPh3‐induced cleavage of the S−S bridge takes place. This complex reacts with pyridine to give a different dimeric palladium complex, [Pd(μ‐S,N‐8‐TT)(PPh3)Py]2, in which each of the two 8‐thio‐(theophylline) anions binds two metals through the N7 and S atoms. The process leading to the palladium complex has also been elucidated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure, and Reactivity of a New Mononuclear Molybdenum(VI) Complex Resembling the Active Center of Molybdenum Oxotransferases
Authors: Dinda Rupam , Sengupta Parbati , Ghosh Saktiprosad , Sheldrick William S.
Published: June 2004

The design, synthesis, and structure determination of a pentacoordinate square‐pyramidal molybdenum(VI) complex MoO2L (where LH2 is a diacidic tridentate ONO donor ligand) is reported. The substrate binding capacity of MoO2L has been demonstrated by the formation and isolation of six‐coordinate octahedral complexes [MoO2L(B)] (where B = imidazole, 1‐methylimidazole, pyridine, or γ‐picoline) and the structures of [MoO2L(Imz)] and [MoO2L(Py)] have been solved by X‐ray crystallography. Oxo transfer of MoO2L to the substrate PPh3 has been demonstrated by the formation of MoOL and [MoOL(bipy)]. Thus, the complex MoO2L behaves as a model for the active center of oxotransfer molybdoenzymes and is of interest in bioinorganic chemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Regio‐ and Stereoselective Copper‐Catalyzed Synthesis of Vicinal Haloamino Ketones from α,β‐Unsaturated Ketones
Authors: Chen Dianjun , Timmons Cody , Chao Steven , Li Guigen
Published: June 2004

The regio‐ and stereoselective aminochlorination of α,β‐unsaturated ketones has been developed. The reaction was conducted with N,N‐dichloro‐p‐toluenesulfonamide (4‐TsNCl2) as the nitrogen/halogen source and CuOTf as the catalyst, at 0 °C to room temperature. This method provides an easy access to vicinal haloamino ketones, with excellent regioselectivity and up to quantitative yields. Both aromatic and aliphatic enones react well with 4‐TsNCl2 under the present system, but give opposite regioselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of 1‐Hydroxymethylene‐1,1‐bis(phosphonic acids) from Acid Anhydrides: Preparation of a New Cyclic 1‐Acyloxymethylene‐1,1‐bis(phosphonic acid)
Authors: Guenin Erwann , Degache Estelle , Liquier Jean , Lecouvey Marc
Published: June 2004

In continuing with our work to find new pathways to bis(phosphonate) structures we report on their synthesis from tris(trimethylsilyl) phosphite and acid anhydride. This new synthesis allows a direct access to a 1‐hydroxymethylene‐1,1‐bis(phosphonic acid) functionalised by a carboxylic function on the side chain. Moreover, we describe the formation of an original cyclic bis(phosphonate) obtained from phthalic anhydride. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Thermal Hydrogenolysis of Nitrogen‐Containing (Hetero)arenes at Elevated Temperature and Pressure
Authors: Cieplik Mariusz K. , Louw Robert
Published: June 2004

The behaviour of the aromatic nitrogen derivatives pyridine P and quinoline Q − and for comparison benzonitrile and azobenzene − was studied under elevated pressure (20 to 30 bar) in a flow reactor with an atmosphere of hydrogen at temperatures ranging from 773 to 1173 K. Compounds were introduced into the reactor admixed with benzene. Efficient removal of the heteroelement was observed, accompanied by deep gasification of the carbon skeletons, at higher temperatures. P reacts much faster than benzene, while Q is a little less reactive than P. The main products were methane, hydrogen cyanide and ammonia. Mechanisms are discussed based on induced decomposition by hydrogen atoms. The facile reaction of P is explained by hydrogen abstraction to give the 2‐pyridyl radical followed by ring opening, a reaction with much better thermochemistry than that for benzene and the phenyl radical. Reaction via (partially) hydrogenated intermediates may also play a part. “Exocyclic” nitrogen − such as in benzonitrile − is readily displaced by hydrogen, while for azobenzene spontaneous fission of the rather weak C−N bond is the major rate‐ (and product‐) determining step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Versatile Route to syn‐ and anti‐α‐Amino β‐Hydroxy Esters from β‐Keto Esters by Dynamic Kinetic Resolution with Ru‐SYNPHOS® Catalyst
Authors: Mordant Céline , Dünkelmann Pascal , Ratovelomanana‐Vidal Virginie , Genet Jean‐Pierre
Published: June 2004

A general and practical synthesis of both syn‐ and anti‐α‐amino β‐hydroxy esters with high levels of selectivity by the use of Ru‐SYNPHOS® catalysts is reported. The key transformations include asymmetric hydrogenations of α‐N‐substituted β‐keto esters protected as α‐amido or α‐amino hydrochloride derivatives, respectively. The RuII‐catalyzed hydrogenation of α‐amino β‐keto ester hydrochlorides affords the corresponding anti‐α‐amino β‐hydroxy esters with high diastereoselectivities (up to 99%) and enantioselectivities (up to 97%) through dynamic kinetic resolution (DKR). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Chemical Fixation of Carbon Dioxide Co‐Catalyzed by a Combination of Schiff Bases or Phenols and Organic Bases
Authors: Shen Yu‐Mei , Duan Wei‐Liang , Shi Min
Published: June 2004

Binaphthyldiamino, ethyldiamino and cyclohexyldiamino Schiff bases can catalyze the reaction of epoxides with carbon dioxide in the presence of catalytic amounts of various organic bases to give the corresponding cyclic carbonates in high yields. The simplest binaphthyldiamino Schiff base, derived from the reaction of binaphthyldiamine with salicylaldehyde, gave the highest yield of cyclic carbonate. This catalytic system can be further simplified by use of a phenol instead of the Schiff base to give the corresponding cyclic carbonates in high yields as well. Mechanistic insights were obtained based on a deuterium labeling experiment. The reaction of aziridines with CO2 and epoxide with CS2 were also examined under the same reaction conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Diastereoselective Radical Tandem Addition‐Cyclization Reactions of Aromatic Tertiary Amines by Semiconductor‐Sensitized Photochemical Electron Transfer
Authors: Marinković Siniša , Hoffmann Norbert
Published: June 2004

The diastereoselective radical tandem addition‐cyclization reaction ofN,N‐dimethylaniline (2) with menthyloxyfuranone1was initiated by photochemically induced electron transfer using inorganic semiconductors (TiO2, ZnS, SiC and SnO2) as sensitizers. The rearomatization step, which also causes the partial reduction of1, was studied by isotopic labeling experiments using deuterated derivatives of2. The influence of the semiconductor surface on these processes has been characterized and compared with the results obtained under homogeneous conditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Tandem Cleavage of Hydrogenated β‐ and γ‐Carbolines − New Practical Synthesis of Tetrahydroazocino[4,5‐b]indoles and Tetrahydroazocino[5,4‐b]indoles Showing Acetylcholinesterase Inhibitory Activity
Authors: Voskressensky Leonid G. , Borisova Tatiana N. , Kulikova Larisa N. , Varlamov Alexej V. , Catto Marco , Altomare Cosimo , Carotti Angelo
Published: June 2004

Hydrogenated γ‐carbolines underwent tandem piperidine ring cleavage on treatment with dimethyl acetylenedicarboxylate (DMAD) or ethyl propiolate (EP) in the presence of alcohols, producing 3‐alkoxymethyl‐substituted indoles in high yields. These compounds were cyclized to tetrahydroazocino[4,5‐b]indoles in the presence of AlCl3. Hydrogenated β‐carbolines produced tetrahydroazocino[5,4‐b]indoles directly upon treatment with EP in ethanol. The resulting azocinoindole derivatives were subjected to a preliminary evaluation of their in vitro acetylcholinesterase (AChE) inhibitory activities. Most of them were found to inhibit AChE with IC50 values in the micromolar range, compound 17 being the most potent (IC50 = 8.7 μM). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Catalytic Cyclopropanation of Fluorine‐Containing Alkenes and Dienes with Diazomethane and Methyl Diazoacetate
Authors: Guseva Ekaterina V. , Volchkov Nikolay V. , Tomilov Yury V. , Nefedov Oleg M.
Published: June 2004

The reactivities of various double bonds in fluorine‐containing unsaturated compounds toward cyclopropanation with diazomethane and methyl diazoacetate with catalysis by copper, rhodium and palladium compounds were studied. In general, the presence of fluorine atoms attached to the double bond or arranged at neighbouring positions exerted a suppressive effect on the cyclopropanation of this bond. As would be expected, diazomethane in the presence of palladium compounds primarily cyclopropanated less highly substituted double bonds. In the case of 2‐fluoro‐3‐methylbutadiene, the reaction took place at both of the double bonds. When methyl diazoacetate was used, [Rh2(OAc)4] was an efficient catalyst, yielding cyclopropanation products on monofluoro‐substituted double bonds in alkenes and cycloalkenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Fluorinated β‐Diketones in Reactions with Diazocyclopropane Generated in situ
Authors: Tomilov Yury V. , Guseva Ekaterina V. , Kostuchenko Irina V. , Ugrak Bogdan I. , Shulishov Evgeny V. , Nefedov Oleg M.
Published: June 2004

Treatment of 1,1‐di‐ and 1,1,1‐trifluoroalkane‐2,4‐diones 10−13 with cyclopropyldiazonium intermediates 2 and 3, generated in situ through the decomposition of N‐cyclopropyl‐N‐nitrosourea 1 by treatment with moist K2CO3, did not result in the expected azo coupling of the cyclopropyldiazonium ion, but afforded the corresponding oxaspiropentanes 14−17 as products of the addition of diazocyclopropane (3) onto one of the carbonyl groups. In addition, the reaction proceeded selectively on the carbonyl groups adjacent to the di‐ or trifluoromethyl substituents. 1,1‐Difluoroacetone reacted analogously with diazocyclopropane (3) generated in situ, giving stable 2‐(difluoromethyl)‐2‐methyloxaspiropentane in approximately 50% yield. The resulting oxaspiropentanes 14−17, on heating or in the presence of lithium iodide, rearranged selectively into cyclobutanones 20−23, while in the presence of Al2O3 they formed mixtures of approximately equal amounts of the corresponding cyclobutanones and the 1‐vinylcyclopropanols 24−27. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Galactosylated 5‐Hydroxylysine Mimetics for Glycopeptide Synthesis
Authors: Marin Julien , Violette Aude , Briand Jean‐Paul , Guichard Gilles
Published: June 2004

The design and synthesis of four galactosylated 5‐hydroxylysine mimetic building blocks (2−5), conveniently protected for solid‐phase glycopeptide synthesis, is described. Our approach features: i) a short and divergent route to the corresponding protected amino acid aglycons 6−9 that involves selective ring‐opening of enantiopure 5‐hydroxylated 6‐oxo‐1,2‐piperidinedicarboxylate 10 and 11 with sodium borohydride in ethanol with formation of the corresponding 1,2‐diol; ii) a common δ‐lactam precursor 12, readily accessible from Boc‐Asp‐OtBu (3 steps, 74% yield), that can be hydroxylated with a high level of asymmetric induction; iii) the use of tetra‐pivaloylated galactosyl bromide as galactosyl donor to avoid or limit orthoester formation. The four galactosylated hydroxylysine analogues 2−5 are suitable building blocks for incorporation into immunodominant peptides derived from type II collagen (CII) and for future investigations aimed at determining the fine specificity of arthritogenic T‐cells in collagen‐induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
New Chiral 1,2‐Diamines and Their Use in Zinc‐Catalyzed Asymmetric Hydrosilylation of Acetophenone
Authors: Bette Virginie , Mortreux André , Ferioli Federico , Martelli Gianluca , Savoia Diego , Carpentier Jean‐François
Published: June 2004

The preparation of two new series of chiral 1,2‐diamines and their use in the [ZnR2‐diamine]‐catalyzed asymmetric hydrosilylation of acetophenone with poly(methylhydrosiloxane) (PMHS) in an aprotic medium is reported. The effect of structural modifications of the secondary diamine ligand, in particular a possible cooperative effect of two different types of chiral centers, on the N‐benzylic side‐arms and on the ethylene bridge of the diamine skeleton, has been investigated. A new diamine ligand giving up to 91% ee is described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synergistic Effect of Pybox Substituents and Lanthanide Cations in Reversing the Asymmetric Induction in the Catalysed Diels−Alder Reaction between 3‐Acryloyl‐1,3‐oxazolidin‐2‐one and Cyclopentadiene
Authors: Desimoni Giovanni , Faita Giuseppe , Guala Matilde , Laurenti Anna
Published: June 2004

The enantioselectivity in the pybox/lanthanide(III) triflate catalysed Diels−Alder reaction between cyclopentadiene and 3‐acryloyl‐1,3‐oxazolidin‐2‐one is profoundly influenced by the presence of a phenyl group in the 5′‐position of the ligand, since it sometimes amplifies, and sometimes reverses the enantioselectivity induced by the 4′‐substituent. The results can be summarised in three points. Of the catalysts derived from (4′R,5′R)‐4‐Me‐5‐Ph‐pybox (6), the ScIII‐based one is both strongly endo‐selective and strongly enantioselective. Several catalysts derived from (4′R,5′R)‐trans‐diphenyl‐pybox (9) give up to 50% yields of exo‐4 and, at least with PrIII and LaIII, induce excellent ee values in both endo and exo adducts. The (4′R,5′S)‐cis‐diphenyl‐pybox (8) is a novel and valuable ligand, since opposite enantiomers can be obtained with good selectivity simply by changing the cation from ScIII to LaIII. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Construction of a Fused Polycyclic Wall within the Cyclodextrin Belt To Ensure a Distorted Cavity: An Unusual trans‐Diequatorial Ring‐Opening Reaction of Cyclodextrin Epoxide Rings
Authors: Fujita Kahee , Fujioka Toshihiro , Shimada Hideaki , Ohta Kazuko , Yoshino Akitoshi , Okabe Yuji , Fukudome Makoto , Yuan De‐Qi
Published: June 2004

In the nucleophilic ring‐opening reaction of 2X,3X‐manno‐epoxides, the incoming nucleophiles attack the 3X‐C position of the epoxide almost exclusively. However, a quite unusual but very interesting reversed regioselectivity is observed when intramolecular hydroxy groups act as nucleophiles, that is, only the attack by 3X−1‐OH at the 2X‐C position of the epoxide is observed. The reaction affords the apparent trans‐diequatorial products and ensures an efficient construction of fused heterocycles within the cyclodextrin belt. In the case of 2I,3I:2II,3II‐di‐manno‐epoxy‐β‐cyclodextrin, a tandem‐type reaction is initiated by the attack by the 3VII‐OH group at the 2I‐C position to generate a fused pentacycle. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Preparation of Sugar Amino Acids by Claisen‐Johnson Rearrangement: Synthesis and Incorporation into Enkephalin Analogues
Authors: Montero Ana , Mann Enrique , Herradón Bernardo
Published: June 2004

We have developed a convenient route for the synthesis of an unsaturated branched sugar bearing a carboxylic acid and an amino group (masked as an azide group) by employing a totally stereoselective Claisen−Johnson rearrangement as the key step. Several Met‐ and Leu‐enkephalin analogues with different substitution patterns at the N‐ and C‐termini were prepared by incorporating this sugar amino acid (SAA) as a substitute for the central Gly−Gly fragment of the parent pentapeptides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Model Compound of the Novel Organic Cofactor CTQ (Cysteine Tryptophylquinone) of Quinohemoprotein Amine Dehydrogenase
Authors: Murakami Yoko , Tachi Yoshimitsu , Itoh Shinobu
Published: June 2004

A model compound of the novel organic cofactor CTQ (cysteine tryptophylquinone) of quinohemoprotein amine dehydrogenase (QH‐AmDH) has been synthesized for the first time by the Michael addition of phenylmethanethiol to the 3‐methyl‐6,7‐indolequinone derivative as a key step. The model compound replicates the characteristic absorption spectrum of native CTQ as well as its redox potential in the γ subunit of QH‐AmDH. Detailed structural and spectroscopic characterizations of the model compound have provided important insights into the substituent effects of the thioether group of CTQ. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A Polymer‐Supported Phosphoramide as a Lewis‐Base Catalyst for the Catalytic Aldol Reaction
Authors: Flowers Robert A. , Xu Xin , Timmons Cody , Li Guigen
Published: June 2004

The aldol reactions between trichlorosilyl enol ethers and aldehydes were catalyzed by an environmentally benign polymer‐supported phosphoramide organocatalyst. Eight examples are reported with moderate to good chemical yields and stereoselectivity. Significant rate enhancements were observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Synthesis of Phenylacetylene Dendrimers Having Sterically Congested Diazo Units and Characterization of Their Photoproducts (Eur. J. Org. Chem. 14/2004)
Authors: Itoh Tetsuji , Maemura Toshiyuki , Ohtsuka Yusuke , Ikari Yoshiyuki , Wildt Holger , Hirai Katsuyuki , Tomioka Hideo
Published: June 2004

The cover picture shows a phenylacetylene dendrimer having 12 diazo units, from which a dodecakiscarbene is generated. Diazo functional groups are usually labile and hence cannot be used as building blocks to prepare more complicated poly(diazo) compounds. We have shown that a diphenyldiazomethane prepared to generate a persistent triplet diphenylcarbene is also stable and can be used as a building block to construct poly(diazo) compounds, which can generate high‐spin polycarbenes. Details are discussed in the article by H. Tomioka et al. on page 2991 ff.
Improved Biodegradability of Ligninsulfonic Acid and Wastewater after Ozonation
Authors: Gorenflo A. , Li Y. , Frimmel F.H.
Published: June 2004

A considerable amount of the constituents in wastewater of the pulp and paper mill industry is not biodegradable. As an alternative to the usual coagulation, flocculation, and sedimentation of the substances, the combination of ozonation and a subsequent biological treatment step has been proposed. Ozonation in combination with microbiological treatment was employed to remove ligninsulfonic acid and refractory organic substances from the effluent of a paper mill wastewater treatment plant. Laboratory experiments showed that ligninsulfonic acid was converted into low‐molecular‐weight acids which were biodegradable.
Experimental Investigation of Drying Behavior of Carrots in a Fluidized Bed with Energy Carrier
Authors: Hatamipour M.S. , Mowla D.
Published: June 2004

A pilot scale fluidized bed dryer with inert particles as energy carrier was used to investigate the drying characteristics of carrot in this type of dryer. Glass beads, hollow steel balls and pieces of dry carrot were used as inert materials. The effects of sample diameter, inert material type, inert material diameter, amount of inert material, air velocity and temperature on the rate of drying were studied. It was found that the presence of inert particles enhances the rate of drying. The results of this study also revealed that, although the rate of drying increased with decreasing sample diameter, increasing of inert material thermal conductivity, and increasing of air temperature, but the inert material diameter and air velocity did not have any significant effect on the rate of drying. The independence of the rate of drying on air velocity in well fluidized systems, indicates that external diffusion is not the controlling step in this process. It was also found that the presence of inert materials caused the drying material to reach its final internal temperature more rapidly. The internal temperature of the drying material, also increased with increasing diameter and thermal conductivity of the inert materials.
Generalized‐α methods for seismic structural testing
Authors: Bonelli A. , Bursi O. S.
Published: June 2004

This paper presents novel predictor–corrector time‐integration algorithms based on the Generalized‐α method to perform pseudo‐dynamic tests with substructuring. The implicit Generalized‐α algorithm was implemented in a predictor–one corrector form giving rise to the implicit IPC–ρ∞ method, able to avoid expensive iterative corrections in view of high‐speed applications. Moreover, the scheme embodies a secant stiffness formula that can closely approximate the actual stiffness of a structure. Also an explicit algorithm endowed with user‐controlled dissipation properties, the EPC–ρb method, was implemented. The resulting schemes were tested experimentally both on a two‐ and on a six‐degrees‐of‐freedom system, using substructuring. The tests indicated that the numerical strategies enhance the fidelity of the pseudo‐dynamic test results even in an environment characterized by considerable experimental errors. Moreover, the schemes were tested numerically on severe non‐linear substructured multiple‐degrees‐of‐freedom systems reproduced with the Bouc–Wen model, showing the reliability of the seismic tests under these conditions. Copyright © 2004 John Wiley & Sons, Ltd.
Three‐dimensional models of reservoir sediment and effects on the seismic response of arch dams
Authors: Maeso O. , Aznárez J. J. , Domínguez J.
Published: June 2004

The important effects of bottom sediments on the seismic response of arch dams are studied in this paper. To do so, a three‐dimensional boundary element model is used. It includes the water reservoir as a compressible fluid, the dam and unbounded foundation rock as viscoelastic solids, and the bottom sediment as a two‐phase poroelastic domain with dynamic behaviour described by Biot's equations. Dynamic interaction among all those regions, local topography and travelling wave effects are taken into account. The results obtained show the important influence of sediment compressibility and permeability on the seismic response. The former is associated with a general change of the system response whereas the permeability has a significant influence on damping at resonance peaks. The analysis is carried out in the frequency domain considering time harmonic excitation due to P and S plane waves. The time‐domain results obtained by using the Fourier transform for a given earthquake accelerogram are also shown. The possibility of using simplified models to represent the bottom sediment effects is discussed in the paper. Two alternative models for porous sediment are tested. Simplified models are shown to be able to reproduce the effects of porous sediments except for very high permeability values. Copyright © 2004 John Wiley & Sons, Ltd.
Pseudo‐dynamic testing of bridges using non‐linear substructuring
Authors: Pinto A. V. , Pegon P. , Magonette G. , Tsionis G.
Published: June 2004

Pseudo‐dynamic tests on a large‐scale model of an existing six‐pier bridge were performed at the ELSA laboratory using the substructuring technique. Two physical pier models were constructed and tested in the laboratory, while the deck, the abutments and the remaining four piers were numerically modeled on‐line. These tests on a large‐scale model of an existing bridge are the first to have been performed considering non‐linear behavior for the modeled substructure. Asynchronous input motion, generated for the specific bridge site, was used for the abutments and the pier bases. Three earthquake tests with increasing intensities were carried out, aimed at the assessment of the seismic vulnerability of a typical European motorway bridge designed prior to the modern generation of seismic codes. The experimental results confirm the poor seismic behavior of the bridge, evidenced by irregular distribution of damage, limited deformation capacity, tension shift effects and undesirable failure locations. Copyright © 2004 John Wiley & Sons, Ltd.
Semi‐empirical model for site effects on acceleration time histories at soft‐soil sites. Part 1: formulation and development
Authors: Bárcena Armando , Esteva Luis
Published: June 2004

A criterion is developed for the simulation of realistic artificial ground motion histories at soft‐soil sites, corresponding to a detailed ground motion record at a reference firm‐ground site. A complex transfer function is defined as the Fourier transform of the ground acceleration time history at the soft‐soil site divided by the Fourier transform of the acceleration record at the firm‐ground site. Working with both the real and the imaginary components of the transfer function, and not only with its modulus, serves to keep the statistical information about the wave phases (and, therefore, about the time variation of amplitudes and frequencies) in the algorithm used to generate the artificial records. Samples of these transfer functions, associated with a given pair of soft‐soil and firm‐ground sites, are empirically determined from the corresponding pairs of simultaneous records. Each function included in a sample is represented as the superposition of the transfer functions of the responses of a number of oscillators. This formulation is intended to account for the contributions of trains of waves following different patterns in the vicinity of both sites. The properties of the oscillators play the role of parameters of the transfer functions. They vary from one seismic event to another. Part of the variation is systematic, and can be explained in terms of the influence of ground motion intensity on the effective values of stiffness and damping of the artificial oscillators. Another part has random nature; it reflects the random characteristics of the wave propagation patterns associated with the different events. The semi‐empirical model proposed recognizes both types of variation. The influence of intensity is estimated by means of a conventional one‐dimensional shear wave propagation model. This model is used to derive an intensity‐dependent modification of the values of the empirically determined model parameters in those cases when the firm‐ground earthquake intensity used to determine these parameters differs from that corresponding to the seismic event for which the simulated records are to be obtained. Copyright © 2004 John Wiley & Sons, Ltd.
Delirium in elderly hospitalised patients: protective effects of chronic rivastigmine usage
Authors: Dautzenberg Paul L. J. , Mulder Leonie J. , Olde Rikkert Marcel G. M. , Wouters Cees J. , Loonen Anton J. M.
Published: June 2004

Objectives

To investigate the efficacy of the chronic usage of the cholinesterase inhibitor rivastigmine in patients with dementia in the prevention of delirium in case of hospitalisation.

Design

Retrospective cohort study.

Setting

Non‐geriatric wards of an 1120 bed general teaching hospital in s‐Hertogenbosch, The Netherlands.

Participants

Of a group of 366 hospitalised patients, treated by the geriatric consultation team from January 2002 until June 2003, the patients who used rivastigmine chronically were compared with a randomly selected subgroup of all patients not treated with rivastigmine.

Measurements

The occurrence and duration of a delirium, co‐morbidity, use of medication, length of hospitalisation and psychosocial data were collected from the medical charts of the geriatric consultation team.

Results

11 patients (3%) were chronic rivastigmine users. A control group of 29 subjects was randomly selected from the non‐rivastigmine users of the patient population. In the group that used rivastigmine five patients (45.5%) developed a delirium, compared with 8 (88.9%) in the control group (p < 0.05).

Conclusions

Chronic rivastigmine use may contribute to the prevention of a delirium in a high‐risk group of elderly hospitalised patients suffering from dementia. Copyright © 2004 John Wiley & Sons, Ltd.
Competence to consent to treatment of geriatric patients: judgements of physicians, family members and the vignette method
Authors: Vellinga A. , Smit J. H. , van Leeuwen E. , van Tilburg W. , Jonker C.
Published: June 2004

Objective

In absence of a gold standard of methods to assess competence, three judgements of competency of geriatric patients are evaluated: the judgements of a physician, the judgement of a family member, and the judgement of an instrument.

Methods

Competence of 80 geriatric patients was judged both by a physician and a family member. Decision making capacity was assessed with a vignette. A vignette describes a treatment choice, after which the following abilities are evaluated: evidencing a choice, understanding, reasoning and appreciating a situation. Cognitive functioning was measured with the Mini‐Mental State Examination.

Results

Most of the geriatric patients were judged competent by all three methods. Disagreement between the three judgements was found for 25 patients. Agreement about incompetence was only reached for one patient. Physicians appeared to be most lenient in their incompetency judgement: only three patients were judged incompetent. These patients scored significantly lower than competent patients on cognitive functioning, the decisional ability of understanding, and the total vignette score. Family members appeared to be most stringent in their judgement: they considered 22 patients incompetent. Incompetent patients scored significantly lower than competent patients on cognitive functioning, reasoning and the total vignette score.

Conclusions

The disagreement between the judgements suggests a difference in factors given emphasis by the three methods. The finding that both the judgement of physicians and family members are associated with the assessment of the vignette, suggests that the vignette method has more than a legal theoretical base and is associated with daily life experience and knowledge as well. Physicians can be helped to assess competence by the vignette method to evaluate decisional abilities and by family members who can provide more information about patients' values. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of combined support for people with dementia and carers versus regular day care on behaviour and mood of persons with dementia: results from a multi‐centre implementation study
Authors: Dröes Rose‐Marie , Meiland Franka , Schmitz Mirjam , van Tilburg Willem
Published: June 2004

Background

A previous study in Amsterdam showed that combined family support in the Meeting Centres Support Programme, in which dementia patients and their carers are both supported by one professional staff member, is more effective in influencing behaviour problems and mood of dementia patients living in the community than non‐integrated support, such as day care only.

Objective

A multi‐centre implementation study tests if similar effects are achieved in other regions of The Netherlands.

Methods

A pretest–posttest control group design was applied. 112 dementia patients who visited psychogeriatric day care in eight community centres across the country and in three nursing homes, and their carers participated in the study. The patients in the experimental group (n = 89) received support from the Meeting Centres Support Programme together with their carers, while the control group (n = 23) received day care only. Behaviour problems (agressive behaviour, inactivity, non‐social behaviour) and mood (dissatisfaction, depressive behaviour) were assessed using standardized observation scales. Quality of life was assessed by interviewing the patients.

Results

After 7 months the Meeting Centres Support Programme, compared to regular day care, showed a moderately positive effect on the degree of total behaviour problems (effect size = 0.52), especially on inactivity (effect size = 0.37) and non‐social behaviour (effect size = 0.60), a large effect on depressive behaviour (effect size = 0.92) and a moderate effect on self‐esteem (effect size = 0.43).

Conclusions

The Meeting Centres Support Programme proves to be more effective than regular day care in influencing behaviour problems, especially inactivity and non‐social behaviour, and depressed mood. Participation in the programme also seems to have a positive effect on self‐esteem, an important aspect of quality of life. These findings surpass the results of the Amsterdam study and confirm the surplus value of the combined family support in the Meeting Centres Support Programme as compared to regular day care for people with mild to severe dementia. Copyright © 2004 John Wiley & Sons, Ltd.
Scoring clock tests for dementia screening: a comparison of two scoring methods
Authors: van der Burg Marjoke , Bouwen Anne , Stessens Johan , Ylieff Michel , Fontaine Ovide , de Lepeleire Jan , Buntinx Frank
Published: June 2004

Objective

To compare the dementia screening performance of two scoring systems of the clock drawing test.

Methods

A sample of 1199 elderly subjects was administered the clock drawing test as part of a study on aging and dementia. The clock drawings were scored using published criteria for the two scoring systems that were compared. Additionally, a selection of 103 drawings was scored by three different raters to evaluate inter‐rater agreement within each of the two methods. For a selection of 473 drawings the final diagnosis on the presence or absence of dementia was known. For these drawings accuracy for the detection of dementia was compared between the two methods.

Results

The four‐item scoring system (Kappa 0.76; sensitivity 0.97; specificity 0.32; PPV 0.53; NPV 0.93) was found to be a little more reliable and as accurate as the six‐item scoring system (Kappa 0.67; sensitivity 0.96; specificity 0.42; PPV 0.56; NPV 0.94).

Conclusion

Since both scoring systems showed largely similar results, primary care physicians and other health care providers should be encouraged to use the four‐item scoring checklist as it is easier and requires less time than the more elaborate checklist of the six‐item system. Copyright © 2004 John Wiley & Sons, Ltd.
Association between subcortical vascular disease on CT and neuropathological findings
Authors: Rossi Roberta , Joachim Catherine , Geroldi Cristina , Combrinck Marc , Esiri Margaret M. , Smith A. David , Frisoni Giovanni B.
Published: June 2004

Background

Small vessel cerebrovascular disease (svCVD) causes cognitive impairment and predicts poorer outcomes in elderly persons. The demonstration of svCVD by structural imaging such as computed tomography (CT) is central to the clinical diagnosis but its accuracy is uncertain.

Objective

The aim of this study was to assess the validity of CT to detect pathologically verified svCVD.

Methods

Leukoaraiosis, patchy lesions, and lacunes were assessed separately in different cerebral regions on CT scans of 87 elderly persons with Mini‐Mental State Examination scores between 0 and 30 enrolled in the OPTIMA project. We rated small vessel disease on pathology separately in the white matter and basal ganglia as absent/mild, moderate, and severe. The presence of microinfarcts was also noted.

Results

The severity of all types of CT lesions was associated with pathological findings. Subjects with absent/mild leukoaraiosis on CT decreased and those with severe leukoaraiosis increased with increasing severity of subcortical small vessel ratings on pathology (31, 18 and 0%; 17, 23 and 50%, respectively; p = 0.028). A similar association was present for patchy lesions (73, 59 and 17%; 7, 18 and 33%, respectively; p = 0.004) and lacune (83, 77 and 50%; 0, 4 and 17%, respectively; p = 0.023). Leukoaraiosis, patchy lesions, and lacunes on CT were associated also with microinfarcts on pathology (p < 0.05).

Conclusion

The standardized assessment of svCVD on CT films at the time of the diagnosis correlates with small vessel disease on pathology at death. Copyright © 2004 John Wiley & Sons, Ltd.
Measuring inequality in self‐reported health—discussion of a recently suggested approach using Finnish data
Authors: Lauridsen Jorgen , Christiansen Terkel , Häkkinen Unto
Published: June 2004

Health surveys often include a general question on self‐assessed health (SAH), usually measured on an ordinal scale with three to five response categories, from ‘very poor’ or ‘poor’ to ‘very good’ or ‘excellent’. This paper assesses the scaling of responses on the SAH question. It compares alternative procedures designed to impose cardinality on the ordinal responses. These include OLS, ordered probit and interval regression approaches. The cardinal measures of health are used to compute and decompose concentration indices for income‐related inequality in health. Results are provided using Finnish data on 15D and the SAH questions. Further evidence emerges for the internal validity of a method used in a pioneering study by van Doorslaer and Jones which was based on Canadian data on the McMaster Health Utility Index Mark III (HUI) and SAH. The study validates the conclusions drawn by van Doorslaer and Jones. It confirms that the interval regression approach is superior to OLS and ordered probit regression in assessing health inequality. However, regarding the choice of scaling instrument, it is concluded that the scaling of SAH categories and, consequently, the measured degree of inequality, are sensitive to characteristics of the chosen scaling instrument. Copyright © 2003 John Wiley & Sons, Ltd.
Primary Productivity in a Polymictic Lake – Temporal Dynamics, Controlling Factors and Trophic State
Authors: Gervais Frank , Behrendt Horst
Published: June 2004

The seasonal and interannual dynamics of phytoplankton biomass, underwater light climate and primary productivity were studied in a phytoplankton‐dominated, polymictic lake (Müggelsee, Berlin, Germany) from 1994 to 1998. Turbidity was relatively high (k0 between 0.4 and 2.5 m–1) and the mixing depth often exceeded the euphotic depth. Therefore light was the most important factor limiting primary productivity. 82% of the observed variability in photosynthetic carbon uptake could be explained by a linear regression of carbon uptake against the product of chlorophyll a concentration and mean underwater irradiance. Annual productivity showed a rather large interannual variability (carbon uptake: 233–358 g C m–2 y–1; net oxygen productivity: 730–1150 g O2 m–2 y–1) that was clearly related to algal biomass and global radiation. Compared to the 1980s, the mean annual primary productivity has decreased by 33%.
A Comparative Analysis of Evenness Index Sensitivity
Authors: Beisel Jean‐Nicolas , Usseglio‐Polatera Philippe , Bachmann Vincent , Moreteau Jean‐Claude
Published: June 2004

Evenness indices are numerous but the lack of knowledge of their properties is a limitation to their biological usefulness. 15 evenness indices, two of them being recently proposed, were studied in this work. We investigated the sensitivity of each index using (1) 189 macroinvertebrate communities sampled in the field, and (2) a set of communities modified in a controlled way.

There is no single way to measure evenness. We demonstrated that a measure should be chosen considering (1) the kind of data analysed and, (2) the index properties wanted by users. Depending on the ecological data set the index should be more sensitive to variations in rare, median or abundant species. For most of macroinvertebrate community analyses, a convenient evenness index requirs to be symmetric, unsensitive to variation on rare taxa, with a large range of variation and can be compared with a diversity index. Depending on diversity measure used, five indices correspond to these criteria: EPielou, EHurlbert, E–ln(D), E1–D, EMI. Our results were summarized in a table which may help users to select a convenient evenness measure according to their specific data. Concerning index properties, three main features that an evenness index should meet are briefly discussed: dependence with richness, symmetry criteria and variation range. A revue of this controversial subject allowed a best understanding of values obtained with evenness measures depending on their own features.
Influence of Bed‐Sediment Features on the Interstitial Habitat Available for Macroinvertebrates in 15 French Streams
Authors: Gayraud Sebastien , Philippe Michel
Published: June 2004

The interstitial space of bed‐sediments is a major component of the stream system as it influences both physical and biological processes and patterns, such as exchanges between surface water and groundwater or the assemblage of invertebrates. To investigate the influence of grain‐size distribution and vertical bed‐packing on the interstitial habitat, we used 99 frozen cores collected from 15 French streams. On our data, overall invertebrate density, density of Chironomidae and taxon richness were more strongly related to effective porosity than to other physical variables describing bed‐sediments. We built two models to quantify the influence of grain‐size distribution and vertical bed‐packing on effective porosity. The effective porosity decreased with increasing grain‐size heterogeneity and was strongly related to grain‐size distribution. These relationships differed with vertical bed‐packing, but were consistent across three geologic types of sediments that varied in particle shape and particle texture. These general relationships suggest that effective porosity could be helpful to better understand the distribution patterns of invertebrates in bed‐sediments.