bluuebunny/crossref_metadata_2025_split huggingface dataset:
Peptidic Amidomonophosphane Ligand for Copper‐Catalyzed Asymmetric Conjugate Addition of Diorganozincs to Cycloalkenones
Authors: Soeta Takahiro , Selim Khalid , Kuriyama Masami , Tomioka Kiyoshi 
Published: March 2007

AbstractPeptidic modification of (S)‐2‐[(diphenylphosphino)methyl]pyrrolidine gave a dipeptide‐connected amidomonophosphane ligand for the highly efficient, copper‐catalyzed asymmetric conjugate addition reaction of organozinc reagents with cycloalkenones, giving 3‐alkylated cycloalkanones in high enantioselectivity of up to 98 % ee. A model that predicts the stereochemistry of the reaction is discussed.
Polymer Incarcerated Ruthenium Catalyst for Oxidation of Alcohols with Molecular Oxygen
Authors: Matsumoto Tsutomu , Ueno Masaharu , Kobayashi Juta , Miyamura Hiroyuki , Mori Yuichiro , Kobayashi Shū 
Published: March 2007

AbstractA polymer incarcerated ruthenium (PI Ru) catalyst for the oxidation of alcohols with molecular oxygen has been developed. The catalyst was prepared from a polystyrene‐based copolymer with ruthenium chloride hydrate as the metal source. The choice of ruthenium species was important to obtain high catalytic activity as well as for the suppression of leaching of ruthenium. In the presence of 5 mol % of PI Ru and 15 mol % of 2,2,6,6‐tetramethylpiperidine N‐oxyl (TEMPO), alcohols were oxidized using molecular oxygen at atmospheric pressure to afford the corresponding aldehydes or ketones in good to excellent yields. The catalyst could be recovered and reused at least ten times without loss of activity.
Catalytic Asymmetric Aldol Reactions of Enolizable Carbon Pronucleophiles with Formaldehyde and Ethyl Glyoxylate
Authors: Fukuchi Isao , Hamashima Yoshitaka , Sodeoka Mikiko 
Published: March 2007

AbstractWe herein describe novel catalytic asymmetric aldol reactions of acidic carbon pronucleophiles including β‐keto esters and specific ketones with reactive electrophiles such as formaldehyde and ethyl glyoxylate. In the presence of a catalytic amount of chiral Pd(II)‐BINAP complexes, the hydroxymethylation of β‐keto esters with paraformaldehyde or formalin was examined, and the corresponding adducts were obtained in good yields with good to high enantioselectivity (ca. 86 % ee). In some cases, the similar Pt(II) complex also worked well to give the products with better enantioselectivity. Furthermore, these complexes were found to promote the aldol reactions of less acidic ketones, and ethyl glyoxylate underwent reaction with 3‐coumaranone and β‐tetralone, affording the aldol products with a significant level of enantioselectivity of up to 83 % ee.
Asymmetric Total Synthesis of Nigerone and ent‐Nigerone: Enantioselective Oxidative Biaryl Coupling of Highly Hindered Naphthols
Authors: Kozlowski Marisa C. , Dugan Elizabeth C. , DiVirgilio Evan S. , Maksimenka Katja , Bringmann Gerhard 
Published: March 2007

AbstractAn enantioselective synthesis of the chiral bisnaphthopyrone natural product nigerone and its enantiomer, ent‐nigerone, has been realized. The use of constrained 2‐naphthol substrates was critical to producing highly functionalized chiral 1,1′‐binaphthols via asymmetric oxidative biaryl coupling with 1,5‐diaza‐cis‐decalin copper complexes. The final natural product was formed via a key eight‐step isomerization process of the coupling product, bisisonigerone, and proceeded with retention of the biaryl configuration. The axial configurations of bisisonigerone and nigerone were definitively established by a combination of circular dichroism (CD) measurements and quantum chemical CD calculations.
Reaction of Tetrahydropyranyl Ethers with Triethylsilyl Trifluoromethanesulfonate–2,4,6‐Collidine Combination: Speculation on the Intermediate, Efficient Deprotection, and Application to Efficient Ring‐Closing Metathesis as a Tether
Authors: Fujioka Hiromichi , Okitsu Takashi , Ohnaka Takuya , Sawama Yoshinari , Kubo Ozora , Okamoto Kazuhisa , Kita Yasuyuki 
Published: March 2007

AbstractThe reaction of tetrahydropyranyl (THP) ethers with triethylsilyl trifluoromethanesulfonate (TESOTf)–2,4,6‐collidine proceeded via collidinium salt intermediates to give the alcohol and 4‐triethylsiloxybutanal in good yields. The structure of the intermediate was confirmed by 1H NMR and FAB‐MS studies and by trapping it with EtOH. The reaction was applied for mild, efficient, and highly chemoselective deprotection method of THP ethers. The characteristic feature of the reaction is that the reaction conditions are weakly basic. Then, the reaction can proceed without affecting acid‐labile protecting groups. Furthermore, the intermediates from alkenol–THP ether were trapped with other alkenols to give acyclic mixed acetals, which were subjected to efficient ring‐closing metathesis by using the tetrahydropyranyl unit as a tether.
A Direct Organocatalytic Entry to Selectively Protected Aldopentoses and Derivatives
Authors: Grondal Christoph , Enders Dieter 
Published: March 2007

AbstractThe proline‐catalysed aldol reaction of 2,2‐dimethyl‐1,3‐dioxan‐5‐one with dimethoxyacetaldehyde is used as the key reaction according to the biomimetic C3+Cn strategy for de novo carbohydrate synthesis. Based on the Whitesides inversion strategy, protected D‐erythro‐pentos‐4‐ulose (de>96 %, ee=94 %) was employed for a rapid and divergent entry to various selectively and partly orthogonal protected aldopentoses and derivatives, like amino sugars, thio sugars, deoxy sugars, 4‐C‐substituted (alkylated) aldopentoses and epoxy sugars.
Effects of Aromatic Substituents on Binaphthyl‐Based Chiral Spiro‐Type Ammonium Salts in Asymmetric Phase‐Transfer Reactions
Authors: Kano Taichi , Lan Quan , Wang Xisheng , Maruoka Keiji 
Published: March 2007

AbstractSpiro‐type phase‐transfer catalysts prepared from two equivalents of a single binaphthyl subunit were designed and applied to the asymmetric alkylation and direct aldol reactions of a glycine derivative. The effects of the substitution pattern of the binaphthyl subunits on the enantioselectivity were also investigated.
Catalytic Enantioselective Tandem Carbonyl Ylide Formation/1,3‐Dipolar Cycloaddition Reactions of α‐Diazo Ketones with Aromatic Aldehydes using Dirhodium(II) Tetrakis[N‐benzene‐fused‐phthaloyl‐(S)‐valinate]
Authors: Tsutsui Hideyuki , Shimada Naoyuki , Abe Takumi , Anada Masahiro , Nakajima Makoto , Nakamura Seiichi , Nambu Hisanori , Hashimoto Shunichi 
Published: March 2007

AbstractThe first successful example of the enantioselective intermolecular 1,3‐dipolar cycloaddition of a chiral dirhodium(II) catalyst‐associated carbonyl ylide with an aromatic aldehyde dipolarophile is described. The tandem carbonyl ylide formation/cycloaddition reactions of 1‐diazo‐5‐aryl‐2,5‐pentanediones with aromatic aldehydes using dirhodium(II) tetrakis[N‐benzene‐fused‐phthaloyl‐(S)‐valinate] as a catalyst provide exclusively exo cycloadducts in up to 92 % ee.
Enantioselective Reduction of 4‐Fluoroacetophenone at High Substrate Concentration using a Tailor‐Made Recombinant Whole‐Cell Catalyst
Authors: Gröger Harald , Rollmann Claudia , Chamouleau Francoise , Sebastien Isabelle , May Oliver , Wienand Wolfgang , Drauz Karlheinz 
Published: March 2007

AbstractA practical and highly efficient biocatalytic synthesis of optically active (R)‐4‐fluorophenylethan‐1‐ol has been developed based on reduction of the corresponding 4‐fluoroacetophenone in the presence of a tailor‐made recombinant whole‐cell biocatalyst, containing an alcohol dehydrogenase and a glucose dehydrogenase. The reaction proceeds in a pure aqueous solvent media at a substrate concentration of ca. 0.5 M, and gives the desired product with high conversion (>95 %), good yield (87 %) and with an excellent enantioselectivity of >99 % ee. In addition, activity tests further showed that also the analogous 2‐ and 3‐fluoroacetophenones are promising substrates.
Dynamic Kinetic Resolution for the Catalytic Asymmetric Total Synthesis of Antithrombotic Agents M58163 and M58169
Authors: Saitoh Fumihiko , Nishida Hidemitsu , Mukaihira Takafumi , Aikawa Kohsuke , Mikami Koichi 
Published: March 2007

AbstractDynamic kinetic resolution is one of the most synthetically useful phenomena for asymmetric synthesis. Dynamic kinetic resolution for the catalytic asymmetric synthesis of a spiro[imidazo[1,2‐a]pyrazine‐2(3H),4′‐piperidin]‐5(1 H)‐one scaffold with a lanthanum‐linked BINOL complex is described. It is also clarified that starting materials, diamine 1 and keto ester 2, play important roles not only as substrates but also as additives to modify an active species of the lanthanum complex. The catalytic asymmetric total syntheses of our antithrombotic agents M58163 and M58169 have thus been achieved via dynamic kinetic resolution.
Asymmetric 1,4‐Addition of Organoboron Reagents to Quinone Monoketals Catalyzed by a Chiral Diene/Rhodium Complex: A New Synthetic Route to Enantioenriched 2‐Aryltetralones
Authors: Tokunaga Norihito , Hayashi Tamio 
Published: March 2007

AbstractA novel synthetic approach to 2‐aryltetralones with high ee has been developed through asymmetric 1,4‐addition of arylboronic acids to naphthoquinone monoketals catalyzed by a rhodium complex with the (R,R)‐Ph‐bod* ligand. The asymmetric addition proceeded in high yields with excellent enantioselectivity.
Metallocene Sulfoxides as Precursors of Metallocenes with Planar Chirality
Authors: Ferber Benoit , Kagan Henri B. 
Published: March 2007

AbstractThe preparation of metallocene sulfoxides and their ortho‐diastereoselective functionalization are described. The applications of enantiopure 1,2‐ and 1,3‐disubstituted metallocenes are reviewed, with special emphasis on the preparation of ligands for asymmetric catalysis. The sulfoxide functionality is a useful, traceless, chiral diastereoselective ortho‐directing group, as explained in the article. It allows one to synthesize a wide range of enantiopure metallocenes with planar chirality and predictible configuration. Most of the examples are related to the ferrocene area.
Distaler Ladungstransport in Peptiden
Authors: Schlag Edward W. , Sheu Sheh‐Yi , Yang Dah‐Yen , Selzle Heinrich L. , Lin Sheng Hsien 
Published: March 2007

AbstractBiologische Systeme transportieren Ladungen und reaktive Prozesse häufig über beträchtliche Entfernungen. Traditionelle Modelle der chemischen Kinetik können solche extremen distalen Prozesse gewöhnlich nicht beschreiben. In diesem Aufsatz betrachten wir ein atomares Modell für eine distale Informationsübertragung, das speziell für Peptide entwickelt wurde. Dabei wird die chemische Reaktivität als Ergebnis distaler Wirkungen betrachtet, die auf einer difunktionalen Zwei‐Stufen‐Kinetik, verbunden mit Bewegungen von Peptiden auf der Sub‐Pikosekundenskala beruht. Das difunktionale Modell ergibt einen hocheffizienten Transport von Ladung und Reaktivität über eine beträchtliche Entfernung in einem isolierten Peptid; in einer wässrigen Umgebung wird dagegen eine sehr niedrige Effizienz gefunden. Dem Modell zufolge findet in einer Peptidumgebung eine ultraschnelle Übertragung von Ladung und Reaktivität über eine beträchtliche Entfernung statt. In einem Protein können viele solcher Domänen aktiv sein.
Distal Charge Transport in Peptides
Authors: Schlag Edward W. , Sheu Sheh‐Yi , Yang Dah‐Yen , Selzle Heinrich L. , Lin Sheng Hsien 
Published: March 2007

AbstractBiological systems often transport charges and reactive processes over substantial distances. Traditional models of chemical kinetics generally do not describe such extreme distal processes. In this Review, an atomistic model for a distal transport of information, which was specifically developed for peptides, is considered. Chemical reactivity is taken as the result of distal effects based on two‐step bifunctional kinetics involving unique, very rapid motional properties of peptides in the subpicosecond regime. The bifunctional model suggests highly efficient transport of charge and reactivity in an isolated peptide over a substantial distance; conversely, a very low efficiency in a water environment was found. The model suggests ultrafast transport of charge and reactivity over substantial molecular distances in a peptide environment. Many such domains can be active in a protein.
The Algorithmically Structured Systematic Exploration of Subject's State of Mind: II Reliability and Construct Validity
Authors: Le Mer Marie‐Noëlle , Stoléru Serge 
Published: March 2007

AbstractObjective: To investigate the reliability and validity of a newly developed semistructured interview, the Algorithmically Structured Systematic Exploration of Subject's State of Mind (Assess_Mind). Method: Twelve scales have been developed and used to rate 86 Assess_Mind interviews conducted with patients undergoing in vitro fertilization treatment. For each rating scale, we assessed interrater reliability, interviewer effect, and construct validity. In addition, a factor analysis of scales was performed. To study the validity of scales and of the factors yielded by factor analysis, patients were assessed with a psychopathological battery including the Child Project Questionnaire, the State‐Trait Anxiety Inventory, the Perceived Stress Scale, and the Ways of Coping Checklist. Results: For 11 of the 12 scales, interrater reliability was fair to excellent. There was no significant interviewer effect affecting any of the scales. In addition, the validity of nine of these 11 scales was demonstrated by their correlations with questionnaires measuring similar constructs. Conclusion: Nine of the Assess_Mind scales appear to have adequate psychometric properties. Copyright © 2007 John Wiley & Sons, Ltd.
The making of a social insect: developmental architectures of social design
Authors: Page Robert E. , Amdam Gro V. 
Published: March 2007

AbstractWe marvel at the social complexity of insects, marked by anatomically and behaviorally distinguishable castes, division of labor and specialization—but how do such systems evolve? Insect societies are composed of individuals, each undergoing its own developmental process and each containing its own genetic information and experiencing its own developmental and experiential environment. Yet societies appear to function as if the colonies themselves are individuals with novel “social genes” and novel social developmental processes. We propose an alternative hypothesis. The origins of complex social behavior, from which insect societies emerge, are derived from ancestral developmental programs. These programs originated in ancient solitary insects and required little evolutionary remodeling. We present evidence from behavioral assays, selective breeding, genetic mapping, functional genomics and endocrinology, and comparative anatomy and physiology. These insights explain how complex social behavior can evolve from heterochronic changes in reproductive signaling systems that govern ubiquitous and ancient relationships between behavior and ovarian development. BioEssays 29:334–343, 2007. © 2007 Wiley Periodicals, Inc.
Cell mechanics and stress: from molecular details to the ‘universal cell reaction’ and hormesis
Authors: Agutter Paul S. 
Published: March 2007

AbstractThe ‘universal cell reaction’ (UCR), a coordinated biphasic response to external (noxious and other) stimuli observed in all living cells, was described by Nasonov and his colleagues in the mid‐20th century. This work has received no attention from cell biologists in the West, but the UCR merits serious consideration. Although it is non‐specific, it is likely to be underpinned by precise mechanisms and, if these mechanisms were characterized and their relationship to the UCR elucidated, then our understanding of the integration of cellular function could be improved. As a step towards identifying such mechanisms, I review some recent advances in understanding cell mechanics and the stress response and I suggest potentially testable hypotheses. There is a particular need for time‐course studies of cellular responses to different stimulus doses or intensities. I also suggest a correspondence with hormesis; re‐investigation of the UCR using modern biophysical and molecular‐biological techniques might throw light on this much‐discussed phenomenon. BioEssays 29:324–333, 2007. © 2007 Wiley Periodicals, Inc.
Nucleomorph genomes: structure, function, origin and evolution
Authors: Archibald John M. 
Published: March 2007

AbstractThe cryptomonads and chlorarachniophytes are two unicellular algal lineages with complex cellular structures and fascinating evolutionary histories. Both groups acquired their photosynthetic abilities through the assimilation of eukaryotic endosymbionts. As a result, they possess two distinct cytosolic compartments and four genomes—two nuclear genomes, an endosymbiont‐derived plastid genome and a mitochondrial genome derived from the host cell. Like mitochondrial and plastid genomes, the genome of the endosymbiont nucleus, or ‘nucleomorph’, of cryptomonad and chlorarachniophyte cells has been greatly reduced through the combined effects of gene loss and intracellular gene transfer. This article focuses on the structure, function, origin and evolution of cryptomonad and chlorarachniophyte nucleomorph genomes in light of recent comparisons of genome sequence data from both groups. It is now possible to speculate on the reasons that nucleomorphs persist in cryptomonads and chlorarachniophytes but have been lost in all other algae with plastids of secondary endosymbiotic origin. BioEssays 29:392–402, 2007. © 2007 Wiley Periodicals, Inc.
Size assessment and growth control: how adult size is determined in insects
Authors: Mirth Christen Kerry , Riddiford Lynn M. 
Published: March 2007

AbstractSize control depends on both the regulation of growth rate and the control over when to stop growing. Studies of Drosophila melanogaster have shown that insulin and Target of Rapamycin (TOR) pathways play principal roles in controlling nutrition‐dependent growth rates. A TOR‐mediated nutrient sensor in the fat body detects nutrient availability, and regulates insulin signaling in peripheral tissues, which in turn controls larval growth rates. After larvae initiate metamorphosis, growth stops. For growth to stop at the correct time, larvae need to surpass a critical weight. Recently, it was found that the insulin‐dependent growth of the prothoracic gland is involved in assessing when critical weight has been reached. Furthermore, mutations in DHR4, a repressor of ecdysone signaling, reduce critical weight and adult size. Thus, the mechanisms that control growth rates converge on those assessing size to ensure that the larvae attain the appropriate size at metamorphosis. BioEssays 29:344–355, 2007. © 2007 Wiley Periodicals, Inc.
What a difference copy number variation makes
Authors: Kehrer‐Sawatzki Hildegard 
Published: March 2007

AbstractDNA copy number variation (CNV) represents a considerable source of human genetic diversity. Recently,1 a global map of copy number variation in the human genome has been drawn up which reveals not only the ubiquity but also the complexity of this type of variation. Thus, two human genomes may differ by more than 20 Mb and it is likely that the full extent of CNV still remains to be discovered. Nearly 3000 genes are associated with CNV. This high degree of variability with regard to gene copy number between two individuals challenges definitions of normality. Many CNVs are located in regions of complex genomic structure and this currently limits the extent to which these variants can be genotyped by using tagging SNPs. However, some CNVs are already amenable to genome‐wide association studies so that their influence on human phenotypic diversity and disease susceptibility may soon be determined. BioEssays 29:311–313, 2007. © 2007 Wiley Periodicals, Inc.
GTP‐binding proteins of the Rho/Rac family: regulation, effectors and functions in vivo
Authors: Bustelo Xosé R. , Sauzeau Vincent , Berenjeno Inmaculada M. 
Published: March 2007

AbstractRho/Rac proteins constitute a subgroup of the Ras superfamily of GTP hydrolases. Although originally implicated in the control of cytoskeletal events, it is currently known that these GTPases coordinate diverse cellular functions, including cell polarity, vesicular trafficking, the cell cycle and transcriptomal dynamics. In this review, we will provide an overview on the recent advances in this field regarding the mechanism of regulation and signaling, and the roles in vivo of this important GTPase family. BioEssays 29:356–370, 2007. © 2007 Wiley Periodicals, Inc.
A unifying new model of cytokinesis for the dividing plant and animal cells
Authors: Dhonukshe Pankaj , Šamaj Jozef , Baluška František , Friml Jiří 
Published: March 2007

AbstractCytokinesis ensures proper partitioning of the nucleocytoplasmic contents into two daughter cells. It has generally been thought that cytokinesis is accomplished differently in animals and plants because of the differences in the preparatory phases, into the centrosomal or acentrosomal nature of the process, the presence or absence of rigid cell walls, and on the basis of ‘outside‐in’ or ‘inside‐out’ mechanism. However, this long‐standing paradigm needs further reevaluation based on new findings. Recent advances reveal that plant cells, similarly to animal cells, possess astral microtubules that regulate the cell division plane. Furthermore, endocytosis has been found to be important for cytokinesis in animal and plant cells: vesicles containing endocytosed cargo provide material for the cell plate formation in plants and for closure of the midbody channel in animals. Thus, although the preparatory phases of the cell division process differ between plant and animal cells, the later phases show similarities. We unify these findings in a model that suggests a conserved mode of cytokinesis. BioEssays 29:371–381, 2007. © 2007 Wiley Periodicals, Inc.
Ultrasensitive peroxynitrite‐based luminescence with L‐012 as a screening system for antioxidative/antinitrating substances, e.g. Tylenol® (acetaminophen), 4‐OH tempol, quercetin and carboxy‐PTIO
Authors: Dyke Knox Van , Ghareeb Erica , Dyke Mark Van , Thiel David H. Van 
Published: March 2007

AbstractPreviously our group developed a water‐soluble antioxidant screening system using the luminescence of the reaction of peroxynitrite and luminol. In the present study we replaced luminol with the luminol‐like compound L‐012. This increases the production of luminescence approximately 100‐fold and therefore, with a higher signal:noise ratio, this new system can detect antioxidation and antinitration effects at lower doses of the inhibitor. We studied acetaminophen (Tylenol®) and its metabolite 3‐nitroacetaminophen, tyrosine and nitrotyrosine and all these substances were inhibitory in a dose‐responsive manner and below micromolar amounts. In addition quercetin, a polyphenol, was highly active (below micromolar amounts) as an antioxidant and antinitrating compound. 4‐OH tempol, the stable free radical, superoxide dismutase (SOD) mimetic, was inhibitory in a dose‐responsive manner and below micromolar amounts. Carboxy‐PTIO was inhibitory at 10 times micromolar amount but not below that dose, which may be related to colour quenching, since the drug is deeply blue, or possibly it is an inhibitor with a slow kinetic profile. Finally, the amino acid tyrosine has been found to be inhibitory in micromolar amounts, similar to acetaminophen. This indicates that tyrosine can act as an antioxidant and antinitration target alone or conjugated in protein, e.g. insulin. Copyright © 2007 John Wiley & Sons, Ltd.