bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lack of change in serum angiotensin-converting enzyme activity during the menstrual cycle
Authors: Sanders Julie , Harris Joanna , Cooper Jackie , Gohlke Peter , Humphries Steve E , Montgomery Hugh , Woods David R 
Published: May 2007

Introduction. The Deletion (D) rather than Insertion (I) variant of the angiotensin-converting enzyme (ACE) gene is associated with higher circulating ACE activity. Meanwhile, coronary risk rises with the menstrual nadir in oestrogen levels, exogenous oestrogen reduces serum ACE activity (with a greater reduction the higher the baseline ACE activity), and pharmacological reduction in ACE activity is cardioprotective. Alterations in coronary risk associated with the menstrual cycle may thus be mediated through (genotype-dependent) changes in ACE activity. We have examined this hypothesis. Materials and methods. Twenty-three healthy female subjects (12 II, 11 DD genotype) were studied. None were taking oral contraceptive agents. Blood was assayed for oestrogen, follicle stimulating hormone (FSH), luteinising hormone (LH), progesterone and ACE activity every three days throughout their menstrual cycle. Results ACE activity was unrelated to oestrogen, FSH or LH during the menstrual cycle, irrespective of ACE genotype. Conclusions. The increase in myocardial ischaemia during low oestrogen phases of the menstrual cycle does not appear mediated through a fall in serum ACE activity.
Variable structure control with sliding sector based on hybrid switching law
Authors: Pan Yaodong , Furuta Katsuhisa 
Published: May 2007

AbstractIn general, a variable structure (VS) control system should be designed such that a sliding mode (or a boundary layer, or a high‐order sliding mode, or a sliding sector), where the reduced‐order system is stable, is reached in finite time, i.e. a reaching movement is necessary for VS control systems. This paper proposes a VS controller without the requirement of reaching movement. With the proposed controller, a system is stabilized by switching the system control input among a set of feedback control laws no matter whether a sliding mode happens or not. Each feedback control law is easy to be designed, because it uses only one of state variables with a fixed plus or minus feedback gain. For ann‐order system, 2nfeedback control laws are needed to realize the proposed VS control. The concept of the sliding sector is used in the paper to show that there exists an area for each feedback control law, inside which a Lyapunov function decreases with the control law although the system may not be stabilized by it alone. A common Lyapunov function for all control laws exists if the system is controllable. Based on the extremum seeking control algorithm, a switching function is defined as the variation between the Lyapunov function and a pre‐determined decrease function. Then a VS control rule is designed such that a series of sliding modes happen with the switching function being a constant and the Lyapunov function decreases in every period after switching once through all control laws. The proposed VS control system is quadratically stable. Simulation results are given to show the convergence of the proposed VS control algorithm. Copyright © 2007 John Wiley & Sons, Ltd.
MOP‐Type Binaphthyl Phosphite and Diamidophosphite Ligands and Their Application in Catalytic Asymmetric Transformations
Authors: Gavrilov Konstantin N. , Lyubimov Sergey E. , Zheglov Sergey V. , Benetsky Eduard B. , Petrovskii Pavel V. , Rastorguev Eugenie A. , Grishina Tatiana B. , Davankov Vadim A. 
Published: May 2007

AbstractMonodentate phosphite and diamidophosphite ligands have been developed based on O‐methyl‐BINOL. These chiral ligands are easy to prepare from readily accessible phosphorylating reagents – (Sa or Ra)‐2‐chlorodinaphtho[2,1‐d:1′,2′‐f][1,3,2]dioxaphosphepine and (2R,5S)‐2‐chloro‐3‐phenyl‐1,3‐diaza‐2‐phosphabicyclo[3.3.0]octane. The new ligands have demonstrated excellent enantioselectivity in the palladium‐catalysed allylic substitution reactions of (E)‐1,3‐diphenylallyl acetate with sodium p‐toluenesulfinate (up to 99 % ee), pyrrolidine (up to 97 % ee), dipropylamine (up to 95 % ee) and dimethyl malonate (up to 99 % ee). In the palladium‐catalysed deracemization of ethyl (E)‐1,3‐diphenylallyl carbonate, up to 96 % enantioselectivity has been achieved. The diamidophosphite ligands have exhibited very good enantioselectivity in the Rh‐catalysed asymmetric hydrogenation of dimethyl itaconate (up to 90 % ee).
Stereoselective Prostereogenic 3‐Oxo Ester Reduction Mediated by a Novel Yeast Alcohol Dehydrogenase Derived from Kluyveromyces marxianus CBS 6556
Authors: Perrone Maria Grazia , Santandrea Ernesto , Scilimati Antonio , Syldatk Christoph 
Published: May 2007

AbstractA yeast alcohol dehydrogenase (ADH) has been purified up to a purification factor value of 21,731‐fold from Kluyveromyces marxianus CBS 6556. The purification procedure consisted of two chromatographic steps (DEAE‐anion exchange and affinity chromatography). The optimal pH was 7, its optimal temperature was 40 °C and its co‐factor was NADPH. This novel ADH efficiently mediated the reduction of 3‐oxo esters with a high degree of stereoselectivity, providing chiral alcohols having the (S) absolute configuration at the newly formed stereogenic centre by delivering the hydride from the re‐face of the prochiral carbonyl compounds.
Gallium Trichloride‐Catalyzed Exhaustive α‐Ethynylation Reaction of 1‐Silylacetylenes
Authors: Amemiya Ryo , Yamaguchi Masahiko 
Published: May 2007

AbstractGallium trichloride (GaCl3) catalyzes the ethynylation reaction of a 1,4‐enyne with chlorosilylacetylene at the propargyl position giving a triethynylvinylmethane. This catalytic method can be applied to the exhaustive α‐ethynylation of 1‐silylacetylenes possessing less acidic propargyl protons, and mono‐, di‐, and triethynylated products are obtained depending on the structure of the starting materials.
Transesterification of Vegetable Oil to Biodiesel using a Heteropolyacid Solid Catalyst
Authors: Chai Fang , Cao Fenghua , Zhai Fengying , Chen Yang , Wang Xiaohong , Su Zhongmin 
Published: May 2007

AbstractA clean, facile, and ecologically friendly method for the production of biodiesel has been developed. A solid acid, namely the heteropolyacid (HPA) Cs2.5H0.5PW12O40, has been used as a heterogeneous catalyst for the production of biodiesel from Eruca sativa Gars. oils (ESG oil) with methanol at a certain temperature. A study for optimizing the reaction conditions such as the reaction time, temperature, the oil to methanol ratio, the amount of catalyst, and the usage times of the catalyst, has been performed. The Cs2.5H0.5PW12O40 heterogeneous acid catalyst shows almost the same activity under the optimized reaction conditions as compared to a conventional homogeneous catalyst such as sodium hydroxide or sulfuric acid, and can easily be separated from the products and can be used for several more runs. The most important features of this catalyst are that the catalytic activity is not effected by the content of free fatty acids and content of water in the vegetable oil and that the esterification can occur at a lower temperature (room temperature) and be finished within a shorter time. The results illustrate that the Cs2.5H0.5PW12O40 is an excellent, water‐tolerant and environmentally benign solid acid catalyst for the production of biodiesel. The fuel properties of ESG biodiesel were found to be in agreement with the ASTM standard.
Quinine‐Catalyzed Enantioselective Michael Addition of Diphenyl Phosphite to Nitroolefins: Synthesis of Chiral Precursors of α‐Substituted β‐Aminophosphonates
Authors: Wang Jian , Heikkinen Lora D. , Li Hao , Zu Liansuo , Jiang Wei , Xie Hexin , Wang Wei 
Published: May 2007

AbstractA quinine‐promoted, enantioselective Michael addition reaction of diphenyl phosphite with nitroalkenes has been developed. This methodology affords a facile access to enantiomerically enriched β‐nitrophosphates, precursors for the preparation of synthetically and biologically useful β‐aminophosphonates.
Amine‐Catalyzed Asymmetric Epoxidation of α,β‐Unsaturated Aldehydes
Authors: Zhao Gui‐Ling , Ibrahem Ismail , Sundén Henrik , Córdova Armando 
Published: May 2007

AbstractThe direct organocatalytic enantioselective epoxidation of α,β‐unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid‐derived imidazolidinones catalyze the asymmetric epoxidation of α,β‐unsaturated aldehydes. In particular, protected commercially available α,α‐diphenyl‐ and α,α‐di(β‐naphthyl)‐2‐prolinols catalyze the asymmetric epoxidation reactions of α,β‐unsaturated aldehydes with high diastereo‐ and enantioselectivities to furnish the corresponding 2‐epoxy aldehydes in high yield with up to 97:3 dr and 98 % ee. The use of non‐toxic catalysts, water and hydrogen peroxide, urea hydroperoxide or sodium percarbonate as the oxygen sources could make this reaction environmentally benign. In addition, one‐pot direct organocatalytic asymmetric tandem epoxidation‐Wittig reactions are described. The reactions were highly diastereo‐ and enantioselective and provide a rapid access to 2,4‐diepoxy aldehydes. Moreover, a highly stereoselective one‐pot organocatalytic asymmetric cascade epoxidation‐Mannich reaction, which proceeds via the combination of iminium and enamine activation, is presented. The mechanism and stereochemistry of the amino acid‐ and chiral pyrrolidine‐catalyzed direct asymmetric epoxidation of α,β‐unsaturated aldehydes are also discussed.
Tandem Catalysis: Access to Ketones from Aldehydes and Arylboronic Acids via Rhodium‐Catalyzed Addition/Oxidation
Authors: Mora Guilhem , Darses Sylvain , Genet Jean‐Pierre 
Published: May 2007

AbstractDirect cross‐coupling reactions of aromatic aldehydes with arylboronic acids afforded ketones in high yields and under mild conditions in the presence of a rhodium catalyst, acetone and a base. This new reaction, involving a formal aldehyde CH bond activation, is believed to proceed via a tandem process involving addition of the organometallic species to the aldehyde followed by oxidation by β‐hydride transfer.
Epoxide Hydrolase‐Catalysed Kinetic Resolution of a Spiroepoxide, a Key Building Block of Various 11‐Heterosteroids
Authors: Bottalla Anne‐Lise , Ibrahim‐Ouali Malika , Santelli Maurice , Furstoss Roland , Archelas Alain 
Published: May 2007

AbstractTwo microbial epoxide hydrolases – i.e., Aspergillus niger (AnEH) and Rhodococcus erythropolis (the so‐called “Limonene EH”: LEH) were used to achieve, for the first time, the biocatalysed hydrolytic kinetic resolution (BHKR) of spiroepoxide rac‐1. This compound is a strategic key building block allowing the synthesis of 11‐heterosteroids. Interestingly enough, the two enzymes exhibited opposite and therefore complementary enantioselectivity allowing us to isolate the residual (R,R)‐1 (from AnEH) and the residual (S,S)‐1 (from LEH) in nearly enantiopure forms (>98 %). Their absolute configurations were determined by X‐ray crystallography. An opposite regioselectivity of the oxirane ring opening for both enantiomers of substrate 1, determined using H218O labelling and chiral GC‐MS analysis, was also observed, corresponding to an attack at the less substituted carbon atom using AnEH, and at the most substituted carbon atom using LEH. A chemical process‐improving methodology was also developed. This allowed us to obtain both enantiomers of the substrate in high enantiomeric purity (99 %) and optimised quantity. In the case of the AnEH, the use of a biphasic (water/isooctane) reaction medium allowed us to increase the global substrate concentration up to 200 g/ L. The preparation of both enantiomers of 1 clearly paves the way to the preparative scale synthesis and biochemical evaluation of the corresponding 11‐heterosteroid enantiomers.
Organocatalytic Enantioselective Decarboxylative Addition of Malonic Half Thioesters to Imines
Authors: Ricci Alfredo , Pettersen Daniel , Bernardi Luca , Fini Francesco , Fochi Mariafrancesca , Herrera Raquel Perez , Sgarzani Valentina 
Published: May 2007

AbstractWe describe a biomimetic organocatalytic enantioselective decarboxylative addition of malonic acid half thioesters to imines. This simple protocol makes use of readily available Cinchona‐derived organocatalysts and nucleophiles at the carboxylate oxidation state. The resulting β‐amino thioesters, being attractive precursors for the preparation of optically active β‐amino acids, are formed in good yields and in up to 79 % ee. As suggested by several mechanistic insights the desired products are formed via initial formation of a thioester acetate enolate via decarboxylation of the malonic acid half thioester, followed by addition to the imine.
Synthesis of Pyrrolizidine, Indolizidine, and Quinolizidine Derivatives Using Ruthenium‐Catalyzed Ring‐Opening Metathesis and Ring‐Closing Metathesis of Cycloalkene‐ynes
Authors: Wakamatsu Hideaki , Sato Yoshihiro , Fujita Reiko , Mori Miwako 
Published: May 2007

AbstractRing‐opening metathesis and ring‐closing metathesis (ROM‐RCM) of a cyclopentene‐yne having an ester moiety was demonstrated using first‐ and second‐generation Grubbs’ catalysts. When the reaction of cycloalkene‐yne was carried out in the presence of 5 mol % of a ruthenium carbene complex under an ethylene atmosphere at room temperature, ROM‐RCM proceeded smoothly to give a pyrrolidine derivative in good yield, which could be converted to a pyrrolizidine derivative. Furthermore, ROM‐RCM of azabicyclo[2.2.1]heptene‐ynes using the second‐generation Grubbs’ catalyst was investigated. When an azabicycloheptene derivative was exposed to a catalytic amount of a ruthenium carbene complex, pyrrolizidine and indolizidine derivatives were obtained in good yields. The distribution of these products depends on the substituents on the alkyne. When azabicyclo[2.2.1]heptene‐ynes bearing large substituents on the alkyne were treated with ruthenium catalyst 1b, a pyrrolizidine derivative was obtained as the major product. ROM‐RCM of azabicyclo[2.2.2]octene‐ynes with 1b afforded quinolizidine derivative 20, although the yield was moderate.
Bioreactors Based on Monolith‐Supported Ionic Liquid Phase for Enzyme Catalysis in Supercritical Carbon Dioxide
Authors: Lozano Pedro , García‐Verdugo Eduardo , Piamtongkam Rungtiwa , Karbass Naima , De Diego Teresa , Burguete M. Isabel , Luis Santiago V. , Iborra José L. 
Published: May 2007

AbstractBioreactors with covalently supported ionic liquid phases (SILP) were prepared as polymeric monoliths based on styrene–divinylbenzene or 2‐hydroxyethyl methacrylate–ethylene dimethacrylate, and with imidazolium units loadings ranging from 54.7 to 39.8 % wt IL per gram of polymer. The SILPs were able to absorb Candida antarctica lipase B (CALB), leading to highly efficient and robust heterogeneous biocatalysts. The bioreactors were prepared as macroporous monolithic mini‐flow systems and tested for the continuous flow synthesis of citronellyl propionate in supercritical carbon dioxide (scCO2) by transesterification. The catalytic activity of these mini‐flow‐bioreactors remained practically unchanged for seven operational cycles of 5 h each in different supercritical conditions. The best results were obtained when the most hydrophobic monolith, M‐SILP‐8‐CALB, was assayed at 80 °C and 10 MPa, reaching a total turnover number (TON) of 35.8×104 mol product/mol enzyme. The results substantially exceeded those obtained for packed‐bed reactors with supported silica‐CALB‐Si‐4 catalyst under the same experimental conditions.
An Unprecedented Rhodium‐Catalyzed Asymmetric Intermolecular Hydroacylation Reaction with Salicylaldehydes
Authors: Stemmler René T. , Bolm Carsten 
Published: May 2007

AbstractAn unprecedented enantio‐ and diastereoselective rhodium‐catalyzed intermolecular hydroacylation reaction of salicylaldehydes with norbornenes is reported in which the corresponding aryl ketones are obtained in high diastereomeric and moderate enantiomeric excesses. It was found that monodentate phosphoramidite ligands gave rise to endo products, while bidentate phosphine ligands catalyzed the reaction to form exo products predominantly.
Convenient Preparation of Chiral α,β‐Epoxy Ketones via Claisen–Schmidt Condensation‐Epoxidation Sequence
Authors: Wang Yongcan , Ye Jinxing , Liang Xinmiao 
Published: May 2007

AbstractA novel Clasisen–Schmidt condensation‐epoxidation sequence of aldehydes and ketones was developed to produce a series of chiral α,β‐epoxy ketones under asymmetric phase‐transfer catalytic conditions. The organocatalytic method reported here can afford chiral α,β‐epoxy ketones under mild conditions with moderate to good yields and up to 96 % ee.
Efficient Heterogeneously Palladium‐Catalysed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3‐Arylpropionic Esters
Authors: Noël Sébastien , Luo Ciahong , Pinel Catherine , Djakovitch Laurent 
Published: May 2007

AbstractA heterogeneous tetrakis(ammine)palladium‐NaY zeolite {[Pd(NH3)4]/NaY} catalyst was applied successfully to the Heck arylation of acrolein diethyl acetal using a large variety of aryl and heteroaryl bromides. Depending on the reaction conditions (Heck versus Cacchi) good to high selectivities toward the 3‐arylpropionic esters or to the cinnamaldehydes were achieved, respectively. Under classical Heck conditions, while the catalyst was found to be stable over the two first runs, it showed significant loss of activity from the third cycle. Under Cacchi conditions, the catalyst could not be reused as it led to high dehalogenation rates. All results indicate that the reactions proceed through dissolved palladium species in the bulk solution (leaching). As observed by transmission electronic microscopic (TEM) analyses, while these species can be trapped and stabilised by the zeolite framework under the Heck conditions, they tend to form large palladium(0) aggregates under the Cacchi conditions leading to dehalogenation rather than to the expected Heck coupling.
Cyclopropyl Building Blocks for Organic Synthesis, 139. Ethyl Cyclopropylidenepyruvate as a Novel Multifunctional Cyclopropyl Building Block: Facile Preparation and Basic Reaction Patterns
Authors: Bagutski Viktor , de Meijere Armin 
Published: May 2007

Abstract1 Tin(II) chloride‐mediated Barbier‐type coupling of ethyl glyoxylate with 2,3‐dibromopropene followed by Simmons–Smith cyclopropanation and subsequent Dess–Martin oxidation, afforded ethyl 3‐(1‐bromocycloprop‐1‐yl)‐2‐oxopropionate (5), a stable precursor of ethyl cyclopropylidenepyruvate (1j), in good overall yield (65 %), even on a multi‐gram scale. The potentially rich chemistry of this novel cyclopropyl building block was illustrated by some basic transformations such as Michael additions of N‐, S‐, O‐ and C‐nucleophiles (10–91 % yields), Diels–Alder reactions with cyclopentadiene (65 %) and 2,3‐dimethylbuta‐1,3‐diene (66 %) as well as [4+2] cycloadditions across the enone moiety of 1j (hetero‐Diels–Alder reactions) with furan and enol ethers (65–79 %), thus opening up a ready access to a wide range of new variously functionalized cyclopropane derivatives.
Palladium‐Catalyzed Cross‐Coupling Reaction Using Arylgermanium Sesquioxide
Authors: Endo Mayuko , Fugami Keigo , Enokido Tatsuki , Sano Hiroshi , Kosugi Masanori 
Published: May 2007

AbstractPowdery reagents obtained by complete alkaline hydrolysis of arylgermanium trichlorides were found to undergo the palladium‐catalyzed cross‐coupling reaction with aryl bromides and iodides in good yields. The reaction is performed in an aqueous medium taking sodium hydroxide as an activator. Some base‐sensitive functionalities such as acetyl and trifluoromethyl groups survived the reaction.
Dopaminergic candidate genes in Tourette syndrome: Association between tic severity and 3′ UTR polymorphism of the dopamine transporter gene
Authors: Tarnok Zsanett , Ronai Zsolt , Gervai Judit , Kereszturi Eva , Gadoros Julia , Sasvari‐Szekely Maria , Nemoda Zsofia 
Published: May 2007

AbstractMultiple evidence suggests an involvement of the dopamine neurotransmitter system in Tourette syndrome (TS). Therefore, dopaminergic candidate genes are in the center of genetic association analyses of TS. In this study, 103 TS patients and their parents have been characterized for different dopamine‐related polymorphisms including the 48 bp variable number of tandem repeats (VNTR) of the dopamine D4 receptor (DRD4) gene, the 40 bp VNTR of the dopamine transporter (DAT1, SLC6A3) gene and the Val158Met polymorphism of the catechol‐O‐methyltransferase (COMT) gene. In addition, the 120 bp duplication and three single nucleotide polymorphisms (SNPs) were assessed in the promoter region of the DRD4 gene. The −616G allele and the 2‐G‐A‐C haplotype (i.e., the 2‐repeat form of the 120 bp sequence ∼ −616G ∼ −615A ∼ −521C combination) were preferentially transmitted, however, these results did not remain significant after correction for multiple testing. Case‐control analyses have also been carried out, resulting in negative findings. On the other hand, using a dimensional approach, the DAT1 40 bp VNTR showed an association with the peak tic‐severity as measured by the Yale Global Tic Severity Scale. Patients with at least one copy of the 9‐repeat allele had significantly more severe symptoms than individuals with the homozygous 10/10 genotype (P = 0.002). In summary, allele frequencies did not differ between cases and controls, but DAT1 genotype accounted for variations of tic severity within the TS group. © 2007 Wiley‐Liss, Inc.
A review of association and linkage studies for genetical analyses of learning disorders
Authors: Caylak Emrah 
Published: May 2007

AbstractLearning disorders (LD) commonly comprise of a heterogeneous group of disorders manifested by unexpected problems in some children's experiences in the academic performance arena. These problems especially comprise of a variety of disorders which may be subclassified to attention‐deficit hyperactivity disorder (ADHD), reading disability (RD), specific language impairment (SLI), speech‐sound disorder (SSD), and dyspraxia. The aim of this review is to summarize the current molecular studies and some of the most exciting recent developments in molecular genetic research on LD. The findings for the association and linkage of LD with candidate genes will help to set the research agendas for future studies to follow. © 2007 Wiley‐Liss, Inc.
Catechol‐O‐methyltransferase polymorphism (COMT) in suicide attempters: A possible gender effect on anger traits
Authors: Baud Patrick , Courtet Philippe , Perroud Nader , Jollant Fabrice , Buresi Catherine , Malafosse Alain 
Published: May 2007

AbstractAnger‐related personality traits are considered contributory risk factors for suicidal behavior. According to twin studies, they are partially under genetic control and their various clinical expressions have been associated with serotonergic and catecholaminergic activities. A functional polymorphism on the human catechol‐O‐methyltransferase (COMT) gene, which codes for the catecholamines inactivating enzymeCOMT, has been shown to influence aggressive and anger‐related traits in various clinical populations. The aim of the present study was to investigate the association between anger traits (as characterized by the State‐Trait Anger Expression Inventory, STAXI) andCOMTVal158Met polymorphism in suicide attempters (n = 427) and control subjects (n = 185). Results showed that the high activity genotype (Val/Val) was more frequent in suicide attempters than in normal controls. Moreover, the Val/Val genotype markedly affected the scores on two STAXI subscales—Trait Anger and Anger Control—in female suicide attempters, thus suggesting a possible gender effect of theCOMTgenotype on a stable personality trait. These results are discussed in the light of recently published data on the effect ofCOMTVal158Met polymorphism on different cognitive and behavioral traits. © 2007 Wiley‐Liss, Inc.