bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis ofbis‐3‐alkyl‐5‐arylhydantoins andbis‐3‐alkyl‐5‐arylthiohydantoins separated by two and four carbon atoms
Authors: Salerni O. Leroy , Van Tyle W. Kent , Mustra David J. , Emerich Kevin S. , Fuerst Douglas E. , Zia‐Ebrahimi M. 
Published: February 2009

AbstractSynthesis of 1,2‐ and 1,4‐bis‐thiohydantoins and hydantoins employing ethylenediamine and 1,4‐diaminobutane as spacers is described. Compounds containing a two carbon bridge were synthesized by alkylation of ethylenediamine with two equivalents of N‐t‐butyl‐α‐(p‐toluenesulfonyloxy)phenylacetamide3. The phenyl isothiocyanate adduct of 3 cyclized in refluxing toluene to form1a. Other isothiocyanate or isocyanate adducts derived from alkylation product 4 required hydrolysis to induce cyclization. Compounds1b‐1fwere obtained in this way. Compounds with a four carbon bridge were obtained by reaction of two equivalents of methyl α‐bromophenyl acetate and 1,4‐diaminobutane to produceN,N'‐bis‐[(α‐phenyl‐α‐methoxycarbonyl)methyl]butylenediamine6. The isothiocyanate or isocyanate adducts from 6 cyclized, without hydrolysis, to form compounds2a‐2e.
A facile synthesis of 3,5‐diaminopyrazole‐4‐carbothioamides and 3,5‐diaminopyrazole‐4‐carboxylates
Authors: Cocco Maria Teresa , Congiu Cenzo , Onnis Valentina , Bernard Angela Maria , Piras Pier Paolo 
Published: February 2009

AbstractSimple and convenient synthesis of hitherto unknown 3,5‐diaminopyrazole‐4‐carbothioamides 3 as well as new ethyl 3,5‐diaminopyrazole‐4‐carboxylates 7 is reported. The key intermediates were 2‐cyano‐propenethioamides 2 and 2‐(ethoxycarbonyl)propenethioamides 5 which were readily obtained by reaction of phenyl isothiocyanate with 3‐(2‐acylhydrazino)‐3‐aminopropenenitriles 1 and ethyl 3‐(2‐acylhydrazino)‐3‐aminopropenoates 4 respectively. Intramolecular cyclization of compounds 2 afforded pyrazole‐4‐carbothioamides 3 while propenethioamides 5 gave pyrazole‐4‐carboxylates 7.
Convenient synthesis of 1,6,7,8‐substituted 2‐(3′,4′‐substituted‐phenyl)‐4‐quinolones via a 4‐ethoxyflavylium salt
Authors: Sato Shingo , Watanabe Takeshi , Kumagai Hironobu , Kitamura Nobuo , Matsuba Shigeru , Kumazawa Toshihiro , Onodera Jun‐Ichi , Suzuki Masanobu 
Published: February 2009

AbstractCondensation of 2‐hydroxyacetophenone with benzaldehyde in the presence of 70% perchloric acid in ethyl orthoformate gave the corresponding 4‐ethoxyflavylium perchlorate, which was treated with aqueous ammonia or methylamine solution to afford 1,6,7,8‐substituted 2‐(3′,4′‐substituted‐phenyl)‐4‐quinolone in fair to good yield.
1,2,3‐Triazolo[4,5‐e]‐1,2,4‐triazolo[3,4‐c]pyrimidines
Authors: Biagi Giuliana , Giorgi Irene , Livi Oreste , Manera Clementina , Scartoni Valerio 
Published: February 2009

AbstractSome new 1,2,3‐triazolo[4,5‐e]‐1,2,4‐triazolo[3,4‐c]pyrimidmes were prepared starting from the corresponding 1,2,3‐triazolo[4,5‐d]pyrimidines via the formation of the 1,2,4‐triazole ring. Thus suitable hydrazino derivatives 6 were condensed with triethyl orthoformate, triethyl orthoacetate and triethyl orthobenzoate to give the expected tricyclic derivatives 7, 8 and 9. Intramolecular cyclization of the ethoxycarbonylhydrazino derivatives 10 gave the tricyclic compounds 11 bearing an hydroxyl group in the 3 position. The v‐triazolo‐s‐triazolopyrimidine derivatives were tested towards the A1 and A2A adenosine receptors in binding assays, but they did not show any receptor affinity.
Ring transformations of heterocyclic compounds. XVIII . Spiro[cyclohexadiene‐indolines] with three stereocenters from pyrylium salts and chiral methyleneindolines — an example of a high diastereoselective ring transformation
Authors: Zimmermann Thomas , Abram Ulrich 
Published: February 2009

AbstractThe diastereoselective synthesis of 6‐aroyl‐3,5‐diarylspiro[cyclohexa‐2,4‐diene‐1,2′‐indolines] 4 possessing three stereocenters from 2,4,6‐triarylpyrylium perchlorates 1 and chiral methyleneindolines 3 (generated in situ by deprotonation of the corresponding 3H‐indolium perchlorates 2) in the presence of triethylamine/acetic acid in ethanol by a 2,5‐[C4+C2] pyrylium ring transformation is reported. Structure elucidation is performed by X‐ray structure determinations of the spiro[cyclohexadiene‐indolines] 4a, 4p and 4t. The influence of various substituents at C‐3 of the methyleneindolines 3 on the stereochemistry of the transformation, mechanistic details as well as spectroscopic data of the products 4 are discussed.
Behaviour of 5,6‐dihydrothieno[2,3‐h]cinnolin‐3(2H)‐one and 5,6‐dihydrothieno[3,2‐h]cinnolin‐3(2H)‐one towards hydrazine. Synthesis of thienocinnolinones and of 4‐aminothienocinnolinones
Authors: Villa Stefania , Cignarella Giorgio , Curzu Michela M. , Pinna Gérard A. , Pini Elena , Toma Lucio 
Published: February 2009

AbstractThe isomeric compounds 5,6‐dihydrothieno[2,3‐h]cinnolin‐3(2H)‐one (7a) and 5,6‐dihydrothieno‐[3,2‐h]cinnolin‐3(2H)‐one (7b) rapidly tautomerise to the corresponding 1,4‐dihydrothienocinnolinones 8a,b when kept in refluxing hydrazine hydrate. With longer reaction times the initially formed 8a,b dehydrogenate to the thienocinnolinones 9a,b which eventually are aminated to 4‐aminothienocinnolinones 10a,b. This behaviour recalls that reported for the related 5,6‐dihydrobenzocinnolin‐3(2H)‐one (1) which under the same conditions undergoes dehydrogenation to benzo[h]cinnolin‐3(2H)‐one (2) followed by 4‐amination to 3, but differs for the stability of the intermediates, for the mechanism of the final amination, and for the higher reaction rate. All these differences can be rationalised in terms of the heats of formation of the intermediates and products of the two series of transformations.
2,4,6‐Trichloropyrimidine. Reaction with sodium amide
Authors: Delia Thomas J. , Meltsner Bernard R. , Schomaker Jennifer M. 
Published: February 2009

AbstractThe first reaction between 2,4,6‐trichloropyrimidine 1 and anionic nitrogen nucleophiles is described. Treatment of 1 with one equivalent of sodium amide gave mixtures of 4‐amino‐2,6‐dichloropyrimidine 2 and 2‐amino‐4,6‐dichloropyrimidine 3. Additional quantities of sodium amide failed to provide either diamino‐ or triaminopyrimidines. Instead, the strongly basic nature of sodium amide led to higher molecular products that were not characterized.
Synthesis of novel quinoxaline‐5‐carboxylic acid derivatives
Authors: Kornberg Brian E. , Nikam Sham S. , Rafferty Michael F. 
Published: February 2009

AbstractThis paper describes the synthesis of several new 2,3‐dimethoxy‐6‐methyl‐7‐nitro‐quinoxaline‐5‐carboxylic acid derivatives (13a‐m) via a multistep synthetic route from 5‐methyl‐1H‐benzo[d][1,3]oxazine‐2,4‐dione (1).
Synthesis of 4,5‐dichloro‐1‐(4,5‐dichloropyridazin‐3‐yl)pyridazin‐6‐one
Authors: Kweon Deok‐Heon , Kang Young‐Jin , Chung Hyun‐A , Park Jung‐Won , Lee Woo Song , Yoon Yong‐Jin , Kim Sung‐Kyu , Shiro Motoo 
Published: February 2009

AbstractThis paper presents the synthesis of 4,5‐dichloro‐1‐(4,5‐dichloropyridazin‐3‐yl)pyridazin‐6‐one from 4,5‐dichloropyridazin‐6‐one.
Synthesis and X‐ray structure of new spiro‐imidazo[2,1‐b]thiazole
Authors: Feng Yaqing , Zhang Weihong , Chen Ligong , Froelich J. , Meretter K. , Sauter F. 
Published: February 2009

AbstractSpiro[5,5]undecane‐3‐one 1 was converted to 4,7‐dihydrospiro[benzo[d]thiazole‐6(5H),1′‐cyclohexane]‐2‐amine 3, which is condensed with bromomethyl (halo)phenyl ketones and cyclized to compounds 5a‐5c. The X‐ray crystallography of the 5b reveals that formation route for 5 is via 3‐position‐substituted‐spiro‐iminothiazole 4.
Synthesis of 5‐cyanopyrazolo[3,4‐b]pyridines in the reaction of 5‐amino‐3‐methyl‐1‐phenylpyrazole with arylidene derivatives of malonodinitrile and ethyl cyanoacetate
Authors: Quiroga Jairo , Alvarado Mario , Insuasty Braulio , Moreno Rodolfo , Raviña Enrique , Estevez Isabel , De Almeida S. Regina H. 
Published: February 2009

AbstractThis paper describes the synthesis of a new series of 6‐amino‐4‐aryl‐5‐cyanopyrazolo[3,4‐b]pyridines 4 and 4‐aryl‐5‐cyano‐6H‐pyrazolo[3,4‐b]pyridin‐6‐ones 5 from the reaction of 5‐amino‐3‐methyl‐1‐phenylpyrazole 1 with arylidene derivatives of malonodinitrile 2 and ethyl cyanoacetate 3. The structure of the final compounds was determined on the basis of nmr measurements, especially by 1H, 1H‐, 1H, 13C‐COSY, DEPT and X‐ray diffraction.
A new selective preparation of ethyl 7‐aminopteridine‐6‐ carboxylate derivatives and related compound
Authors: Yamada Yoichi , Yasuda Heinosuke , Yoshihara Yuichi , Yoshizawa Kazue 
Published: February 2009

AbstractA series of ethyl 7‐amino‐2,4‐dioxopteridine‐6‐carboxylates 4 and ethyl 7‐amino‐4‐oxo‐2‐thioxopteridine‐6‐carboxylates 5, of interest biologically, has been prepared in one step from the reaction of such vicinal‐diamines as 1,3‐dialkyl‐5,6‐diaminouracils 2 or 1,3‐dialkyl‐5,6‐diamino‐2‐thiouracils 3 with diethyl (E)‐2,3‐dicyanobutenedioate (1). Moreover, ethyl 3‐amino[1,2,4]triazino[2,3‐a]‐1H‐benzimidazole‐2‐carboxylate (11) was also obtained from the reaction between 1,2‐diamino‐1H‐benzimidazole (10) and 1. The structural studies of 4, 5, and 11 prepared were carried out by nmr experiments in some details.
Synthesis and reactivity of 1,2,4‐triazolo[1,5‐c]quinazolines
Authors: Pfeiffer Wolf‐Diethard , Bodtke Anja , Mücke Jana , Hetzheim Annemarie , Pazdera Pavel 
Published: February 2009

AbstractThe preparation of 1,2,4‐triazolo[1,5‐c]quinazolines 4a‐d, 5, 8a‐d by cyclocondensation of 1a‐c with carboxylic acids and carboxylic anhydrides, respectively, is described. By different pathways, the 5‐thioxo‐5,6‐dihydro‐1,2,4‐triazolo[1,5‐c]quinazolines 4a‐d react with hydrazine hydrate or amines with the formation of 5‐substituted 1,2,4‐triazolo[1,5‐c]quinazolines 9 and 10a‐d. Cyclocondensation of 9 with carboxylic acids, carboxylic anhydrides, and nitrous acid, respectively, leads to the new anellated heterocycles bis‐1,2,4‐triazolo[4,3‐a:1,5‐c]quinazoline 13 and tetrazolo [1,5‐a]‐1,2,4‐triazolo[1,5‐c]quinazoline (14).
New synthesis of substituted isoindolines from furans via epoxyisoindolines
Authors: Mance A. D. , Borovička B. , Karaman B. , Jakopčić K. 
Published: February 2009

AbstractThe preparation of substituted N‐arylisoindolines 3 from simple furan derivatives 1 is reported. Oxatricycloadducts 2, readily accessible by intramolecular Diels‐Alder reaction are susceptible to acidic reagents yielding aromatized products 3 by a ring‐opening reaction via intermediate carbocation.
Thermal‐ and Sun‐Promoted Generation of Silver Nanoparticles Embedded into Poly(vinyl alcohol) Films
Authors: Bernabò Marco , Pucci Andrea , Galembeck Fernando , Leite Carlos Alberto de Paula , Ruggeri Giacomo 
Published: February 2009

AbstractNanocomposites based on poly(vinyl alcohol) and silver nanoparticles were efficiently prepared by sun‐ and thermal‐promoted reduction processes. Uniaxial drawing of the Ag/PVA nanocomposites favoured the anisotropic distribution of silver particles, providing oriented films with polarisation‐dependent tunable optical properties. These dichroic properties were more pronounced for nanocomposites produced by sun exposition, which provided more compact and interacting metal clusters. The results obtained suggest the nanocomposite films could find potential applications as colour polarising filters, radiation responsive polymeric objects and smart flexible films in packaging applications.magnified image
Vibrational spectroscopy of bare and solvated ionic complexes of biological relevance
Authors: Polfer Nick C. , Oomens Jos 
Published: February 2009

AbstractThe low density of ions in mass spectrometers generally precludes direct infrared (IR) absorption measurements. The IR spectrum of an ion can nonetheless be obtained by inducing photodissociation of the ion using a high‐intensity tunable laser. The emergence of free electron lasers (FELs) and recent breakthroughs in bench‐top lasers based on nonlinear optics have now made it possible to routinely record IR spectra of gas‐phase ions. As the energy of one IR photon is insufficient to cause dissociation of molecules and strongly bound complexes, two main experimental strategies have been developed to effect photodissociation. In infrared multiple‐photon dissociation (IR‐MPD) many photons are absorbed resonantly and their energy is stored in the bath of vibrational modes, leading to dissociation. In the “messenger” technique a weakly bound van der Waals atom is detached upon absorption of a single photon. Fundamental, historical, and practical aspects of these methods will be presented. Both of these approaches make use of very different methods of ion preparation and manipulation. While in IR‐MPD ions are irradiated in trapping mass spectrometers, the “messenger” technique is generally carried out in molecular beam instruments. The main focus of this review is the application of IR spectroscopy to biologically relevant molecular systems (amino acids, peptides, proteins). Particular issues that will be addressed here include gas‐phase zwitterions, the (chemical) structures of peptides and their collision‐induced dissociation (CID) products, IR spectra of gas‐phase proteins, and the chelation of metal–ligand complexes. Another growing area of research is IR spectroscopy on solvated clusters, which offer a bridge between the gas‐phase and solution environments. The development of state‐of‐the‐art computational approaches has gone hand‐in‐hand with advances in experimental techniques. The main advantage of gas‐phase cluster research, as opposed to condensed‐phase experiments, is that the systems of interest can be understood in detail and structural effects can be studied in isolation. It will be shown that IR spectroscopy of mass‐selected (bio)molecular systems is now well‐placed to address specific questions on the individual effect of charge carriers (protons and metal ions), as well as solvent molecules on the overall structure. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:468–494, 2009
Hyperglycemic choreoathetosis: Role of the putamen in pathogenesis
Authors: Kandiah Nagaendran , Tan Kevin , Lim C.C. Tchoyoson , Venketasubramanian Narayanaswamy 
Published: February 2009

AbstractHyperglycemic choreoathetosis (HC) is an uncommon syndrome often associated with hyperintensity of the basal ganglia on MRI. We performed a retrospective review of cases with HC to characterize the clinical, biochemical, and neuroimaging (CT, MRI, and MR spectroscopy) findings and to propose a mechanism for this syndrome. Seven HC patients with a mean age of 75.1 years, mean blood glucose of 27.4 mmol/L, and mean plasma osmolarity of 313.4 mmol/L were studied. All had MR‐T1 hyperintensity of the putamen on the side contralateral to the choreoathetosis. Two patients had additional hyperintensity of the globus pallidus while one also had involvement of the caudate. On MR‐T2, 2 patients showed hyperintensity, 2 isointensity, and 3 hypointensity in the putamen. MR spectroscopy showed elevated choline and reduced N‐acetylaspartate; two patients also had elevated myoinositol levels. Our findings suggest that the putamen has a central role in HC, and MR spectroscopy supports neuronal dysfunction in the putamen. Biochemical and neuroimaging findings support hyperviscosity as the most plausible mechanism. © 2009 Movement Disorder Society
Cysteine elevation in levodopa‐treated patients with Parkinson's disease
Authors: Müller Thomas , Kuhn Wilfried 
Published: February 2009

AbstractHomocysteine, cysteine, and cysteinyl‐glycine are all metabolically interrelated. Levodopa/decarboxylase inhibitor (LD/DCI) administration increases total homocysteine (tHcy) plasma levels. Objectives were to investigate associations between LD/DCI intake, concentrations of tHcy, cysteine, and cysteinyl‐glycine in PD patients and healthy controls. Cysteine levels were significant lower in controls and PD patients with tHcy below the treshold of 15 [μmol/L] when compared with PD patients with tHcy above 15. Cysteinyl‐glycine did not significantly differ between the three cohorts. Significant associations appeared between tHcys and cysteine in PD patients. tHcy and cysteine concentrations correlated to LD/DCI intake and severity of PD. The cysteine increase may be due to the significant higher dosing of daily LD/DCI and the significant higher morning LD/DCI dose 1 hour before blood sampling in PD patients with tHcy above 15 when compared with the remaining PD patients and the controls. The correlation outcomes support the view that LD/DCI intake may also increase cysteine. © 2009 Movement Disorder Society
Technical note: Traffic intensity estimation
Authors: Kiessler Peter C. , Lund Robert 
Published: February 2009

AbstractThis note examines estimation of the traffic intensity in an M/G/1 queue. We show that the ratio of sample mean service times to the sample mean interarrival times has undesirable sampling properties. To remedy this, two alternative estimators are introduced. © 2009 Wiley Periodicals, Inc. Naval Research Logistics 2009
Space‐Mapping and Optimal Shape Design
Authors: Marburger Jan 
Published: February 2009

AbstractOptimal shape design is a common problem in practice. In most cases this means that a complex geometry has to be optimized such that it satisfies a desired quantity. The direct optimization is very difficult and time consuming, if it is possible at all. Therefore, often only simplified models are derived and optimized. In general this does not yield an optimal solution. For this reason the space–mapping method is introduced, which combines the results of the complex model, e.g. a 3D model, and a simplified model, e.g. a 1D or 2D model. The derivation of a simplified model of a filter device and the following optimization is presented. Finally, the advantages of the space–mapping method applied to this example is shown. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimal PID controller of robots under stochastic uncertainty
Authors: Schacher Michael 
Published: February 2009

AbstractIn practice often it is not possible to specify exact model parameters. Hence, precomputed controller based on some parameter estimates can produce bad results.In this presentation the aim is to combine classical PID control theory and stochastic optimisation methods in order to obtain robust optimal feedback control.The method works with cost functions being minimized and takes into account stochastic parameter varations.After Taylor expansion to calculate expected cost functions and a few transformations an approximate deterministic substitute PID control problem follows. Here, retaining only linear terms, approximation of expectations and variances of the expected cost functions can be calculated explicitly. By means of splines, numerical approximations of the objective function and the differential equations are obtained then.Using stochastic optimization methods, random parameter variations are incorporated into the optimal control process. Hence, robust optimal feedback controls are obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Projection‐Based Model Reduction for Time‐Varying Descriptor Systems Using Recycled Krylov Subspaces
Authors: Hossain Mohammad‐Sahadet , Benner Peter 
Published: February 2009

AbstractWe will present a projection approach for model reduction of linear time–varying descriptor systems based on earlier ideas in the work of Philips and others. The idea behind the proposed procedure is based on a multipoint rational approximation of the monodromy matrix of the corresponding differential–algebraic equation. This is realized by orthogonal projection onto a rational Krylov subspace. The algorithmic realization of the method employs recycling techniques for shifted Krylov subspaces and their invariance properties. The proposed method works efficiently for macromodels, such as time varying circuit systems and models arising in network interconnection, on limited frequency ranges. Bode plots and step response are used to illustrate the performance of the reduced order models. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Horizontale Positionierung des Plasmagefäßes des Fusionsexperimentes Wendelstein 7‐X
Authors: Bartkowiak René , Woernle Christoph , Schauer Felix , Tereshchenko Andrey , Missal Bernd 
Published: February 2009

AbstractAm Institut für Plasmaphysik (IPP) in Greifswald soll in den nächsten Jahren das Fusionsexperiment Wendelstein 7‐X (W7‐X) durchgeführt werden, welches als Ziel hat, einen Nachweis über die Eignung des Stellarators als Herzstück eines Fusionskraftwerkes zu erbringen. Das Plasmagefäß des W7‐X muss vertikal abgestützt sowie horizontal zentriert und justiert werden, um u.a. Kollisionen des Plasmagefäßes mit dem Plasma oder umgebenden Komponenten zu verhindern. Das Designkonzept für die horizontale Abstützung und Zentrierung sieht ein System von einstellbaren Pendelstützen und Stellschrauben vor. Auf Grundlage eines elastokinematischen FE‐Modells wird für die Stellgrößen ein Optimierungsalgorithmus entwickelt, der es ermöglicht, in Abhängigkeit von einer zu wählenden Gewichtung die Lageabweichung sowie den Verspannungszustand zu minimieren. Unter Ausnutzung der geometrischen Symmetrieeigenschaften des Systems kann die Anzahl der Messungen zur Identifikation der benötigten Systemparameter stark verringert werden. Die Ergebnisse werden mittels des FE‐Modells validiert. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Matrix formulation of the motion equations of a rigid body and identification of the ten inertia characteristics
Authors: Atchonouglo K. , Dumitriu D. , Monnet T. , Vallée C. 
Published: February 2009

AbstractThe motion equations of a rigid body involve ten inertial characteristics: the mass, the mass center position and the inertia matrix. In order to identify these ten inertia characteristics, we propose an approach unifying them in a 4 × 4 positive definite symmetric matrix. The translation vector and the rotation matrix of the rigid body are also gathered in a 4 × 4 matrix. Therefore the motion equations are formulated as an equality between 4 × 4 skew–symmetric matrices: one representing the sum of external forces and torques, the second representing the dynamic force and torque. The identification is performed by a projected conjugate gradient algorithm developped in the 10–dimensional linear space of 4 × 4 symmetric matrices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An approach for optimization of robot‐generated rigid‐body interpolation using dynamic criteria
Authors: Geu Flores Francisco , Kecskeméthy Andrés 
Published: February 2009

AbstractThe present paper describes an approach for generating spatial trajectories in multibody systems including rigid–body rotations such that dynamic criteria such as forces, accelerations, velocities, etc. as well as limiting restrictions for the motion–generating mechanical device, e.g., a robot, can be considered. The task is to find a rigid–body interpolation that fulfills optimality criteria at the target trajectory as well as in the mechanical system. Application of general optimization methods fails due to the difficulty of finding feasible initial guesses that will converge. The present approach proposes to decouple the general problem into two stages, a first stage in which a pure trajectory optimization is carried out without regard of the mechanical system, and a second stage in which the carrying mechanical system is incorporated. The trajectory planning involves the use of splines of 5–th order as well as an SQP optimization for determining the spline support points as design variables. The approach is illustrated for the example of the generalized waiter problem. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)