bluuebunny/crossref_metadata_2025 huggingface dataset:
Tamoxifen‐loaded microspheres based on mixtures of poly(D,L‐lactide‐co‐glycolide) and poly(D,L‐lactide) polymers: Effect of polymeric composition on drug release and in vitro antitumoral activity
Authors: Fenández A. , Teijón C. , Benito M. , Iglesias I. , Lozano R. , Teijón J. M. , Blanco M. D.
Published: November 2011

Mixtures of different bioerosionable polyesters were used to prepare microparticulated tamoxifen delivery systems to achieve anticancer effects in breast malignant cancer cells. Tamoxifen (TMX) was included into microspheres (MS) formulated via spray‐drying. Mixtures of poly(D,L‐lactide‐co‐glycolide) (PLGA) of different lactide/glycolide proportions (50 : 50 and 75 : 25) and poly(D,L‐lactic acid) (PLA) were used. The average diameter of the resultant TMX‐loaded microparticles was in the range 1.04 ± 0.51–1.55 ± 0.95 μm. The encapsulation efficiency of TMX was between 97.8% [48.9 ± 0.1 TMX (μg)/MS (mg)] and 69.6% [36.6 ± 0.1 TMX (μg)/MS (mg)] depending on the polymeric composition of the formulation. Drug burst effect was not observed. TMX was released from the polymeric matrices in a sustained release manner between 11 and 58 days depending on polymeric composition of microspheres. TMX‐loaded microspheres showed high efficacy in causing cell death in MCF7 breast malignant cancer cells. Thus, these TMX‐loaded PLGA‐based microspheres hold potential to treat breast malignant cancer cells. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Structure and thermal behavior of poly(L‐lactic acid) clay nanocomposites: Effect of preparation method as a function of the nanofiller modification level
Authors: Marras Sotirios I. , Zuburtikudis Ioannis
Published: November 2011

The structural and thermal characteristics of poly(L‐lactic acid)/layered‐silicate hybrid materials that were produced via two different routes, namely by solvent casting and by melt mixing, were compared in association with the degree of clay modification. Investigation of the produced materials' structure revealed that, at low modification levels, melt blending is necessary in dispersing the amine‐treated clay into the polymer matrix. At intermediate degrees of modification, both techniques are capable of swelling the silicate clay with the solution casting to be a more effective method. Thermal measurements showed that the clay modification level influences significantly the thermal stability of both solution and melt processed hybrids. Moreover, the material derived from melt mixing displayed a higher onset decomposition temperature. The glass transition temperature of the polymer was not significantly affected by the preparation method followed. However, the crystallization process was found to be strongly dependent on both the preparation method and the degree of clay modification. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Bifunctional silane (TESPD) effects on improved mechanical properties of silica containing nitrile‐butadiene rubber/poly(vinyl chloride) compound
Authors: Kim Kwang‐Jea
Published: November 2011

Organo bifunctional silane (TESPD) is added into silica containing NBR/PVC blend and its effects are investigated with respect to the vulcanization property, the processability, and the physical property. The addition of the TESPD into silica filled NBR/PVC compound increases the degree of crosslinking by formation of a strong three‐dimensional network structure between silica surface and rubber matrix via coupling reaction, which results in improved mechanical properties. It also improves the processability of the compound compared to the Control compound. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Investigating the surface properties of polyurethane based anti‐graffiti coatings against UV exposure
Authors: Rabea A. Mohammad , Mirabedini S. M. , Mohseni M.
Published: November 2011

A permanent anti‐graffiti coating based on a polyurethane resin was prepared by incorporating different levels of an OH‐functional silicone modified polyacrylate additive. Static contact angle measurements and dynamic mechanical thermal analysis (DMTA) were employed to evaluate surface free energy and mechanical properties of the coating specimens, respectively. Effect of ageing condition on the graffiti properties of the coating samples was evaluated utilizing an accelerated weathering test. Color changes, surface morphology, and variations in the mechanical properties were also examined prior to and after being exposed to UV irradiation for 864 h in a QUV chamber. Results showed that surface free energy of the samples decreased with replacement of polyol with additive up to 5 mol %. A Scanning electron microscope equipped with energy dispersive X‐ray detector revealed that for the samples containing more than 5 mol % additive, there was an enrichment of silicone at the interface of films and air. At long exposure times and higher concentrations of additive, depreciation of graffiti properties was seen. DMTA and attenuated total reflectance‐fourier transform infra‐red studies before and after ageing showed that the silicone additive tended to degrade while it could cause an increase in crosslinking density. Water contact angles and atomic force microscopy images after ageing revealed that the cause of the depletion in anti‐graffiti properties was attributed to the deterioration of the silicone additive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Preparation and studying properties of polybutene‐1/thermoplastic starch blends
Authors: Kaseem Mosab , Hamad Kotiba , Deri Fawaz
Published: November 2011

Starch as an inexpensive and renewable source has been used as a filler for environmental friendly plastics for about two decades. In this study, glycerol was used as a plasticizer for starch to enhance the dispersion and the interfacial affinity in thermoplastic starch (TPS)/polybutene‐1(PB‐1) blend. PB‐1 was melt blended with TPS using a single screw extrusion process and molded using injection molding process to investigate the rheological and mechanical properties of these blends. Rheological properties were studied using a capillary rheometer, and the Bagley's correction was performed. Mechanical analysis (stress–strain curves) was performed using Testometric M350‐10 kN. The rheological properties showed that the melt viscosity of the blend is less than that of PB‐1, and the flow activation energy at a constant shear stress of the blend increases with increasing glycerol content in the blend. The mechanical experiments showed that both stress and strain at break of the blends are less than that of PB‐1, whereas the Young's modulus of the most blends is higher than that of PB‐1 which confirms the filling role of TPS in the blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Morphology and hydrogen‐bond restricted crystallization of poly(butylene succinate)/cellulose diacetate blends
Authors: Zhou Weihua , Yuan Shuaishuai , Chen Yiwang , Bao Le
Published: November 2011

Poly(butylene succinate)/cellulose diacetate (PBS/CDA) blends were prepared by the solution blending method from poly(butylene succinate) (PBS) and cellulose diacetate (CDA). The influence of hydrogen bond on the structure, morphology, crystallization, as well as the physical properties of PBS/CDA blends was significantly investigated. The fourier transform infrared spectroscopy (FTIR) results indicated that the carbonyl groups of PBS shifted to higher wavenumbers and disappeared at the content of 60% CDA, due to the formation of hydrogen bond between PBS and CDA. The wide‐angle X‐ray diffractometer (WAXD) and differential scanning calorimeter (DSC) analysis suggest that the crystallization of PBS was significantly restricted by the incorporation of CDA, which is also attributed to the hydrogen bonding. The scanning electron miscroscope (SEM) and polarized optical microscopy (POM) results revealed that PBS and CDA were miscible without appearance of obvious phase separation. The hydrogen bonding interaction led to the change of decomposing mechanism of blends as determined by thermogravimetric analysis (TGA), as well as the increase of the elongation at break due to the reduced crystallinity of PBS. The existence of CDA led to the decrease of water contact angle, showing of the improved hydrophilicity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Thermal and mechanical behavior of natural rubber latex‐silica aerogel film
Authors: On Ng Kui , Rashid Azura Abdul , Nazlan Mohd Muhid Mohd , Hamdan Halimaton
Published: November 2011

A major problem in most natural rubber latex (NRL) commonly encountered like other polymer is susceptibility to mechanical properties and thermal degradation; particularly in thin film due to the presence of double bonds in the main chain. Therefore, it is desirable to seek for ways of improving these properties. Silica aerogel is a material with extraordinary properties was believed to have potential enhance properties in NRL films because of its high specific surface area. Therefore, based on the unique character of silica aerogel, NRL‐silica aerogel film was developed by latex compounding and dry coagulant dipping to form thin film where silica aerogel acts as filler. Silica aerogel, synthesized from rice husk was dispersed in a ball‐mill using distilled water for NRL compounding. Results indicate that increasing silica aerogel loading enhances the mechanical properties of the NRL‐silica aerogel film. Effects of postvulcanization processes were also investigated, whereby the best reinforcing effect was obtained at 4 phr silica aerogel loading with leaching postvulcanization condition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Zur Richtlinie für die Nachrechnung von Straßenbrücken im Bestand (Nachrechnungsrichtlinie)
Authors: Marzahn Gero
Published: November 2011

Aufgrund des gestiegenen Schwerverkehrs sowie gestiegener Achs‐ und Gesamtgewichte der Fahrzeuge ist eine Nutzungsänderung für die Straßenbrücken eingetreten. Zur Sicherung der Zukunftsfähigkeit des Straßennetzes sind daher Ertüchtigungsmaßnahmen mit dem Ziel einer Tragfähigkeitsverbesserung mit üblichen Instandsetzungsmaßnahmen zu kombinieren. Eine zutreffende Bewertung der Bauwerke hinsichtlich Tragfähigkeit, Gebrauchstauglichkeit, Dauerhaftigkeit und Ermüdungssicherheit unter Berücksichtigung des vorhandenen Bauwerkzustands ist ein grundlegender Schritt dazu.

Die Nachrechnungsrichtlinie soll für die Bewertung der Bauwerke einheitliche Standards, aber auch Hilfestellung vorgeben, damit Tragfähigkeit und Gebrauchstauglichkeit bestehender Straßenbrücken realistisch beurteilt werden können und die Nachrechnungsergebnisse für eine Entscheidungsfindung nachvollziehbar und vergleichbar werden.

About the Provisions for evaluating necessary upgrades of older road bridges

While analyzing traffic volume on current German autobahns, it became obvious that the planned capacity of most highway bridges has been almost exceeded by daily traffic volume, including increasingly heavy trucks with rising numbers of axles and load size.

In fact, to ensure future long‐term serviceability of the German Autobahn system, there is no way around refurbishing most of these bridges, by combining ordinary maintenance work with strengthening measures, and replacing numerous others as well. A realistic assessment of existing highway bridges that comprises bearing capacity, serviceability, and fatigue resistance in order to evaluate their structural health is a widely accepted prerequisite for a long‐lasting refurbishment strategy. The provisions reported here for evaluating necessary upgrades of older bridges provide an appropriate tool for setting uniform standards in assessing existing highway bridges to ensure comparability of results and the conclusions drawn from them.
Outcomes following surgery without radiotherapy for rectal cancer
Authors: Mathis K L , Larson D W , Dozois E J , Cima R R , Huebner M , Haddock M G , Wolff B G , Nelson H , Pemberton J H
Published: November 2011

Background

This study determined survival and recurrence rates following curative resection of rectal cancer without radiotherapy.

Methods

This was a retrospective review of the Mayo Clinic database of patients with rectal cancer treated with curative intent using surgery alone from 1990 to 2006. Patients who received neoadjuvant chemotherapy or radiation therapy and those who had any postoperative radiotherapy were excluded. Details were collected from the database and patient records using a protocol approved by the institutional review board.

Results

Some 655 consecutive patients with rectal cancer treated with curative intent using surgery alone were identified; 397 had stage I disease, 125 stage II and 133 stage III. Four hundred and nine patients underwent anterior resection (AR) and 246 abdominoperineal resection (APR). Median follow-up was 62 months. The 5-year rate of local recurrence was 4·3 per cent, disease-free survival 90·0 per cent and cancer-specific survival 91·5 per cent. Stage-specific and all-stage disease-free survival did not differ significantly between AR and APR. The 5-year cumulative local recurrence rate was lower following AR than APR (3·6 versus 5·5 per cent; P = 0·321). There were only two patients with positive margins and type of operation was not significant on multivariable analysis.

Conclusion

Well-performed, standardized APRs have similar local recurrence to AR. Radiation therapy may not confer much additional benefit. Copyright © 2011 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.
Dynamic Substrate Enhancement for the Identification of Specific, Second‐Site‐Binding Fragments Targeting a Set of Protein Tyrosine Phosphatases
Authors: Schmidt Marco F. , Groves Matthew R. , Rademann Jörg
Published: November 2011

Protein tyrosine phosphatases (PTPs) are key regulators in living systems and thus are attractive drug targets. The development of potent, selective PTP inhibitors has been a difficult challenge mainly due to the high homology of the phosphotyrosine substrate pockets. Here, a strategy of dynamic substrate enhancement is described targeting the secondary binding sites of PTPs. By screening four different PTPs from bacterial (MptpA) and human origin (PTP1B, HePtp, Shp2) with this assay, specific fragments were identified. One highly specific fragment that binds to the secondary site of Mycobacterium tuberculosis protein tyrosine phosphatase A (MptpA) was characterized in order to validate the assay concept. Finally by covalently linking the secondary fragment to a phosphotyrosine mimetic, a moderately active but highly specific inhibitor of MptpA was obtained.
Generation of a Mono‐ubiquitinated PCNA Mimic by Click Chemistry
Authors: Eger Silvia , Castrec Benoît , Hübscher Ulrich , Scheffner Martin , Rubini Marina , Marx Andreas
Published: November 2011

Genotoxic stress results in more than 50 000 damaged DNA sites per cell per day. During DNA replication, processive high‐fidelity DNA polymerases generally stall at DNA lesions and have to be displaced by translesion synthesis DNA polymerases, which are able to bypass the lesion. This switch is mediated by mono‐ubiquitination of the processivity factor proliferating cell nuclear antigen (PCNA). To further investigate the regulation of the DNA polymerase exchange, we developed an easy and efficient method to synthesize site‐specifically mono‐ubiquitinated PCNA by click chemistry. By incorporating artificial amino acids that carry an azide (Aha) or an alkyne (Plk) in their side chains, into ubiquitin (Ub) and PCNA, respectively, we were able to link the two proteins site‐specifically by the CuI‐catalyzed azide–alkyne cycloaddition. Finally, we show that the synthetic PCNA–Ub is able to stimulate DNA synthesis by DNA polymerase δ, and that DNA polymerase η has a higher affinity for PCNA–Ub than to PCNA.
Defined Presentation of Carbohydrates on a Duplex DNA Scaffold
Authors: Schlegel Mark K. , Hütter Julia , Eriksson Magdalena , Lepenies Bernd , Seeberger Peter H.
Published: November 2011

A new method for the spatially defined alignment of carbohydrates on a duplex DNA scaffold is presented. The use of anN‐hydroxysuccinimide (NHS)‐ester phosphoramidite along with carbohydrates containing an alkylamine linker allows for on‐column labeling during solid‐phase oligonucleotide synthesis. This modification method during solid‐phase synthesis only requires the use of minimal amounts of complex carbohydrates. The covalently attached carbohydrates are presented in the major groove of the B‐form duplex DNA as potential substrates for murine type II C‐type lectin receptors mMGL1 and mMGL2. CD spectroscopy and thermal melting revealed only minimal disturbance of the overall helical structure. Surface plasmon resonance and cellular uptake studies with bone‐marrow‐derived dendritic cells were used to assess the capability of these carbohydrate‐modified duplexes to bind to mMGL receptors.
Metal‐Ion‐Dependent Folding of a Uranyl‐Specific DNAzyme: Insight into Function from Fluorescence Resonance Energy Transfer Studies
Authors: He Ying , Lu Yi
Published: November 2011

Fluorescence resonance energy transfer (FRET) has been used to study the global folding of an uranyl (UO22+)‐specific 39E DNAzyme in the presence of Mg2+, Zn2+, Pb2+, or UO22+. At pH 5.5 and physiological ionic strength (100 mM Na+), two of the three stems in this DNAzyme folded into a compact structure in the presence of Mg2+ or Zn2+. However, no folding occurred in the presence of Pb2+ or UO22+; this is analogous to the “lock‐and‐key” catalysis mode first observed in the Pb2+‐specific 8–17 DNAzyme. However, Mg2+ and Zn2+ exert different effects on the 8–17 and 39E DNAzymes. Whereas Mg2+ or Zn2+‐dependent folding promoted 8–17 DNAzyme activity, the 39E DNAzyme folding induced by Mg2+ or Zn2+ inhibited UO22+‐specific activity. Group IIA series of metal ions (Mg2+, Ca2+, Sr2+) also caused global folding of the 39E DNAzyme, for which the apparent binding affinity between these metal ions and the DNAzyme decreases as the ionic radius of the metal ions increases. Because the ionic radius of Sr2+ (1.12 Å) is comparable to that of Pb2+ (1.20 Å), but contrary to Pb2+, Sr2+ induces the DNAzyme to fold under identical conditions, ionic size alone cannot account for the unique folding behaviors induced by Pb2+ and UO22+. Under low ionic strength (30 mM Na+), all four metal ions (Mg2+, Zn2+, Pb2+, and UO22+), caused 39E DNAzyme folding, suggesting that metal ions can neutralize the negative charge of DNA‐backbone phosphates in addition to playing specific catalytic roles. Mg2+ at low (<2 mM) concentration promoted UO22+‐specific activity, whereas Mg2+ at high (>2 mM) concentration inhibited the UO22+‐specific activity. Therefore, the lock‐and‐key mode of DNAzymes depends on ionic strength, and the 39E DNAzyme is in the lock‐and‐key mode only at ionic strengths of 100 mM or greater.
The Porosity, Acidity, and Reactivity of Dealuminated Zeolite ZSM‐5 at the Single Particle Level: The Influence of the Zeolite Architecture
Authors: Aramburo Luis R. , Karwacki Lukasz , Cubillas Pablo , Asahina Shunsuke , de Winter D. A. Matthijs , Drury Martyn R. , Buurmans Inge L. C. , Stavitski Eli , Mores Davide , Daturi Marco , Bazin Philippe , Dumas Paul , Thibault‐Starzyk Fréderic , Post Jan A. , Anderson Michael W. , Terasaki Osamu , Weckhuysen Bert M.
Published: November 2011

A combination of atomic force microscopy (AFM), high‐resolution scanning electron microscopy (HR‐SEM), focused‐ion‐beam scanning electron microscopy (FIB‐SEM), X‐ray photoelectron spectroscopy (XPS), confocal fluorescence microscopy (CFM), and UV/Vis and synchrotron‐based IR microspectroscopy was used to investigate the dealumination processes of zeolite ZSM‐5 at the individual crystal level. It was shown that steaming has a significant impact on the porosity, acidity, and reactivity of the zeolite materials. The catalytic performance, tested by the styrene oligomerization and methanol‐to‐olefin reactions, led to the conclusion that mild steaming conditions resulted in greatly enhanced acidity and reactivity of dealuminated zeolite ZSM‐5. Interestingly, only residual surface mesoporosity was generated in the mildly steamed ZSM‐5 zeolite, leading to rapid crystal coloration and coking upon catalytic testing and indicating an enhanced deactivation of the zeolites. In contrast, harsh steaming conditions generated 5–50 nm mesopores, extensively improving the accessibility of the zeolites. However, severe dealumination decreased the strength of the Brønsted acid sites, causing a depletion of the overall acidity, which resulted in a major drop in catalytic activity.
Total Synthesis of (−)‐Brevenal: A Streamlined Strategy for Practical Synthesis of Polycyclic Ethers
Authors: Ebine Makoto , Fuwa Haruhiko , Sasaki Makoto
Published: November 2011

We describe a streamlined strategy for the practical synthesis of trans‐fused polycyclic ethers and its application to a concise total synthesis of (−)‐brevenal, a new pentacyclic polyether natural product with intriguing biological activities. The B‐, D‐, and E‐rings were constructed by TEMPO/PhI(OAc)2‐mediated oxidative lactonization of the corresponding 1,6‐diols, with minimal need for manipulation of oxygen functionalities. The B‐ and E‐ring lactones were appropriately functionalized by Suzuki–Miyaura coupling of lactone‐derived enol phosphates and subsequent stereoselective hydroboration. The A‐ring was formed by our mixed thioacetalization methodology. The AB‐ and DE‐ring fragments were assembled through Suzuki–Miyaura coupling, and the C‐ring was forged in the same manner as that for the A‐ring. More than two grams of the pentacyclic polyether core of (−)‐brevenal have been synthesized by the synthetic route developed in this study.
Oxidation of Zn(Cys)4 Zinc Finger Peptides by O2 and H2O2: Products, Mechanism and Kinetics
Authors: Bourlès Emilie , Isaac Manon , Lebrun Colette , Latour Jean‐Marc , Sénèque Olivier
Published: November 2011

The reactivity of a series of Zn(Cys)4 zinc finger model peptides towards H2O2 and O2 has been investigated. The oxidation products were identified by HPLC and ESI‐MS analysis. At pH<7.5, the zinc complexes and the free peptides are oxidised to bis‐disulfide‐containing peptides. Above pH 7.5, the oxidation of the zinc complexes by H2O2 also yields sulfinate‐ and sulfonate‐containing overoxidised peptides. At pH 7.0, monitoring of the reactions between the zinc complexes and H2O2 by HPLC revealed the sequential formation of two disulfides. Several techniques for the determination of the rate constant for the first oxidation step corresponding to the attack of H2O2 by the Zn(Cys)4 site have been compared. This rate constant can be reliably determined by monitoring the oxidation by HPLC, fluorescence, circular dichroism or absorption spectroscopy in the presence of excess ethyleneglycol bis(2‐aminoethyl ether)tetraacetic acid. In contrast, monitoring of the release of zinc with 4‐(2‐pyridylazo)resorcinol or of the thiol content with 5,5′‐dithiobis(2‐nitrobenzoate) did not yield reliable values of this rate constant for the case in which the formation of the second disulfide is slower than the formation of the first. The kinetic measurements clearly evidence a protective effect of zinc on the oxidation of the cysteines by both H2O2 and O2, which points to the fact that zinc binding diminishes the nucleophilicity of the thiolates. In addition, the reaction between the zinc finger and H2O2 is too slow to consider zinc fingers as potential sensors for H2O2 in cells.
A Stereodivergent Strategy for the Preparation of Corynantheine and Ipecac Alkaloids, Their Epimers, and Analogues: Efficient Total Synthesis of (−)‐Dihydrocorynantheol, (−)‐Corynantheol, (−)‐Protoemetinol, (−)‐Corynantheal, (−)‐Protoemetine, and Related Natural and Nonnatural Compounds
Authors: Zhang Wei , Bah Juho , Wohlfarth Andreas , Franzén Johan
Published: November 2011

Here we present a general and common catalytic asymmetric strategy for the total and formal synthesis of a broad number of optically active natural products from the corynantheine and ipecac alkaloid families, for example, indolo[2,3‐a]‐ and benzo[a]quinolizidines. Construction of the core alkaloid skeletons with the correct absolute and relative stereochemistry relies on an enantioselective and diastereodivergent one‐pot cascade sequence followed by an additional diastereodivergent reaction step. This allows for enantio‐ and diastereoselective synthesis of three out of four possible epimers of the quinolizidine alkaloids that begin from common and easily accessible starting materials by using a common synthetic route. Focus has been made on excluding protecting groups and limiting isolation and purification of synthetic intermediates. This methodology is applied in the total synthesis of the natural products (−)‐dihydrocorynantheol, (−)‐hirsutinol, (−)‐corynantheol, (−)‐protometinol, (−)‐dihydrocorynantheal, (−)‐corynantheal, (−)‐protoemetine, (−)‐(15S)‐hydroxydihydrocorynantheol, and an array of their nonnatural epimers. The potential of this strategy is also demonstrated in the synthesis of biologically interesting natural product analogues not accessible through synthetic elaboration of alkaloid precursors available from nature, for example, thieno[3,2‐a]quinolizidine derivatives. We also report the formal synthesis of (+)‐dihydrocorynantheine, (−)‐emetine, (−)‐cephaeline, (−)‐tubulosine, and (−)‐deoxytubulosine.
Highly Enantioselective Synthesis of Tertiary Boronic Esters and their Stereospecific Conversion to other Functional Groups and Quaternary Stereocentres
Authors: Scott Helen K. , Aggarwal Varinder K.
Published: November 2011

Organoboron compounds are useful in asymmetric synthesis. We have developed an efficient methodology for the highly enantioselective synthesis of tertiary boronic esters from the corresponding secondary benzylic alcohols. Further stereospecific transformations of the boronic ester moiety are described including the preparation of tertiary alcohols, C‐tertiary amines and tertiary arylalkanes. Several homologations of tertiary boronic esters have also been developed for the construction of quaternary stereocentres.
Enantioselective IrI‐Catalyzed Carbocyclization of 1,6‐Enynes by the Chiral Counterion Strategy
Authors: Barbazanges Marion , Augé Mylène , Moussa Jamal , Amouri Hani , Aubert Corinne , Desmarets Christophe , Fensterbank Louis , Gandon Vincent , Malacria Max , Ollivier Cyril
Published: November 2011

Enantioenriched bicyclo[4.1.0]hept‐2‐enes were synthesized by IrI‐catalyzed carbocyclization of 1,6‐enynes. No chiral ligands were used, CO and PPh3 were the only ligands bound to iridium. Instead, the stereochemical information was localized on the counterion of the catalyst, generated in situ by reaction of Vaska’s complex (trans‐[IrCl(CO)(PPh3)2]) with a chiral silver phosphate. Enantiomeric excesses up to 93 % were obtained when this catalytic mixture was used. 31P NMR and IR spectroscopy suggest that formation of the trans‐ [Ir(CO)(PPh3)2]+ moiety occurs by chlorine abstraction. Moreover, density functional theory calculations support a 6‐endo‐dig cyclization promoted by this cationic moiety. The chiral phosphate anion (OP*) controls the enantioselectivity through formation of a loose ion pair with the metal center and establishes a CH⋅⋅⋅OP* hydrogen bond with the substrate. This is a rare example of asymmetric counterion‐directed transition‐metal catalysis and represents the first application of such a strategy to a CC bond‐forming reaction.
ChemInform Abstract: Caesium Tetrachlorido Aurate(III), CsAuCl4.
Authors: Kraus Florian
Published: November 2011

The crystal structure of the title compound is determined by single crystal XRD at 150 K.
ChemInform Abstract: Rational Design of Complex Borides — One‐Electron‐Step Evolution from Soft to Semi‐Hard Itinerant Ferromagnets in the New Boride Series Ti2FeRu5‐nRhnB2 (1 ≤ n ≤ 5).
Authors: Fokwa Boniface P. T. , Lueken Heiko , Dronskowski Richard
Published: November 2011

The new series of title compounds is prepared by arc melting of stoichiometric mixtures of the elements and characterized by XRD and magnetic measurements.
ChemInform Abstract: Water Exchange Reactivity and Stability of Cobalt Polyoxometalates under Catalytically Relevant pH Conditions: Insight into Water Oxidation Catalysis.
Authors: Lieb Dominik , Zahl Achim , Wilson Elizabeth F. , Streb Carsten , Nye Leanne C. , Meyer Karsten , Ivanovic‐Burmazovic Ivana
Published: November 2011

Water exchange on the Co centers in Na10 [Co4(H2O)2 (α‐PW9O34)2] (I) in the catalytically relevant pH region between 6 and 10 is investigated by 17O NMR spectroscopy and ultrahigh‐resolution electrospray ionization mass spectrometry to gain insight into the elementary reaction steps involved in the overall water oxidation process.
ChemInform Abstract: Structure Refinement and Magnetic Properties of Ce2RuAl3 and a Group‐Subgroup Scheme for Ce5Ru3Al2.
Authors: Mishra Trinath , Hoffmann Rolf‐Dieter , Schwickert Christian , Poettgen Rainer
Published: November 2011

Ce2RuAl3 is prepared by high‐frequency melting of the elements in a sealed tantalum tube followed by annealing at 1070 K for 4 h.
ChemInform Abstract: Benzylic‐Acetoxylation of Alkylbenzenes with PhI(OAc)2 in the Presence of Catalytic Amounts of TsNH2 and I2
Authors: Baba Haruka , Moriyama Katsuhiko , Togo Hideo
Published: November 2011

The introduction of an acetoxy or benzoyloxy group to the benzylic position of alkylbenzenes is achieved using hypervalent iodine compounds (II) in the presence of iodine and sulfonamides.
ChemInform Abstract: sp3 C—H Bond Activation with Ruthenium(II) Catalysts and C(3)‐Alkylation of Cyclic Amines.
Authors: Sundararaju Basker , Achard Mathieu , Sharma Gangavaram V. M. , Bruneau Christian
Published: November 2011

N‐Protected cyclic amines are regioselectively alkylated at the 3‐position by reaction with aromatic or aliphatic aldehydes using an optimized catalytic system.
ChemInform Abstract: Synthesis of Bi‐ and Tetracatenar Highly Fluorinated Compounds for Grafting on Silicone Materials.
Authors: Malfait Stephane , Gerard Stephane , Plantier‐Royon Richard , Mignani Gerard , Portella Charles
Published: November 2011

The preparation of several new compounds containing up to four perfluorooctyl chains is reported.
ChemInform Abstract: Stereoselective Synthesis of Functionalized Cyclopropane Derivatives via α‐Thiocyanate Ketone‐Based Three‐Component Reaction.
Authors: Wu Fei‐Yue , Li Ying , Feng Hui , Wu Qiong , Jiang Bo , Shi Feng , Tu Shu‐Jiang
Published: November 2011

A direct one‐pot method allows the synthesis of spiro‐substituted as well as polysubstituted trans‐cyclopropanes in a highly diastereoselective manner.
ChemInform Abstract: Seven‐Membered Ring Formation from Cyclopropanated Oxo‐ and Epoxyallylsilanes.
Authors: Pulido Francisco J. , Barbero Asuncion , Castreno Pilar
Published: November 2011

New and stereoselective methods to prepare methylenecycloheptanols are reported.
ChemInform Abstract: Synthesis of Internal Fluorinated Alkenes via Facile Aryloxylation of Substituted Phenols with Aryl Trifluorovinyl Ethers.
Authors: Moody Justin D. , VanDerveer Don , Smith Dennis W. Jr. , Iacono Scott T.
Published: November 2011

The reaction affords vinyl substitution products as (E)/(Z)‐mixtures if NaH is used as base.
ChemInform Abstract: Effect of High Pressure on the Organocatalytic Asymmetric Michael Reaction: Highly Enantioselective Synthesis of γ‐Nitroketones with Quaternary Stereogenic Centers.
Authors: Kwiatkowski Piotr , Dudzinski Krzysztof , Lyzwa Dawid
Published: November 2011

Hydrostatic pressure is essential to achieve the synthesis of various cyclic nitroketones with high yields and excellent enantioselectivities.
ChemInform Abstract: Copper/Oxalohydrazide/Ketone Catalyzed Synthesis of Primary Arylamines via Coupling of Aryl Halides with Aqueous Ammonia in Water.
Authors: Li Ying , Zhu Xinhai , Meng Fei , Wan Yiqian
Published: November 2011

The reactions can also be carried out at room temperature, albeit with prolonged reaction times from one to several days.
ChemInform Abstract: Switching of Enantioselectivity in the Catalytic Addition of Diethylzinc to Aldehydes by Regioisomeric Chiral 1,3‐Amino Sulfonamide Ligands.
Authors: Hirose Takuji , Sugawara Kazuyuki , Kodama Koichi
Published: November 2011

The 1,3‐amino sulfonamides efficiently promote the asymmetric addition of ZnEt2 to various aldehydes.
ChemInform Abstract: A Recyclable Fluorous Thiourea Organocatalyst for the Chemoselective Oxidation of Sulfides.
Authors: Huang Yi‐Bo , Yi Wen‐Bin , Cai Chun
Published: November 2011

A diphenylthiourea with a fluorinated side chain is shown to be an efficient catalyst for the chemoselective oxidation of sulfides to sulfoxides.
ChemInform Abstract: Cavitand Supported Tetraphosphine: Cyclodextrin Offers a Useful Platform for Suzuki—Miyaura Cross‐Coupling.
Authors: Zaborova Elena , Deschamp Julia , Guieu Samuel , Bleriot Yves , Poli Giovanni , Menand Mickael , Madec David , Prestat Guillaume , Sollogoub Matthieu
Published: November 2011

A new α‐cyclodextrin based tetraphosphine hybrid (CYTEP) is synthesized which displays exceptionally high TON (up to 340 000 000 000) and TOF numbers (up to 1 000 000 000 h‐1) in Suzuki—Miyaura coupling reactions.
ChemInform Abstract: Palladium‐Catalyzed Sonogashira Reactions of Aryl Amines with Alkynes via in situ Formation of Arenediazonium Salts.
Authors: Wu Xiao‐Feng , Neumann Helfried , Beller Matthias
Published: November 2011

A novel protocol for the Pd‐catalyzed coupling of anilines with aromatic and aliphatic alkynes is described.
ChemInform Abstract: Gold‐Catalyzed Approach to Multisubstituted Fulvenes via Cycloisomerization of Furan/Ynes.
Authors: Chen Yifeng , Liu Yuanhong
Published: November 2011

Treatment of enynes of type (III) and (VI) with AuCl(PPh3)/AgOTf in CH2Cl2 or THF allows a new and mild access to multisubstituted fulvenes bearing (E)‐ or (Z)‐alkene units.
ChemInform Abstract: Pd‐Catalyzed Cycloisomerization—Allylation of 4‐Alkynones: Synthesis of 5‐Homoallylfuran Derivatives.
Authors: Saito Akio , Enomoto Yohei , Hanzawa Yuji
Published: November 2011

The sequence affords 5‐homoallyl furans or dihydrofuran (V).
ChemInform Abstract: Chiral Biscinchona Alkaloid Promoted Asymmetric Allylic Alkylation of 3‐Substituted Benzofuran‐2(3H)‐ones with Morita—Baylis—Hillman Carbonates.
Authors: Liu Cong , Tan Bo‐Xuan , Jin Jia‐Lu , Zhang Yue‐Yan , Dong Nan , Li Xin , Cheng Jin‐Pei
Published: November 2011

The alkaloid efficiently promotes the coupling of 3‐substituted benzofuranones with carbonates giving 3,3‐disubstituted benzofuranones with moderate to high diastereo‐ and enantioselectivity.
ChemInform Abstract: Regioselective Oxidative Coupling Reactions of 3‐Substituted Thiophenes with Arylboronic Acids.
Authors: Schnapperelle Ingo , Breitenlechner Stefan , Bach Thorsten
Published: November 2011

The reaction of thiophene substrates bearing an ester or phosphonate groups proceeds with excellent regioselectivity at the C4 position.
ChemInform Abstract: o‐Iodoxybenzoic Acid (IBX): A Versatile Reagent for the Synthesis of N‐Substituted Pyrroles Mediated by β‐Cyclodextrin in Water.
Authors: Murthy S. Narayana , Nageswar Y. V. D.
Published: November 2011

A new protocol allows the aromatization of various 1‐benzylpyrrolidines and L‐proline derivatives to afford the corresponding pyrroles.
ChemInform Abstract: A Facile Synthesis of Symmetrical and Unsymmetrical Bis(indolyl)acetamides Mediated by Protic Acid.
Authors: Shang Hai , Hao Fei‐Yue , Pan Li , Chen Hong , Cheng Mao‐Sheng
Published: November 2011

Dimerization of hydroxyindolylacetamides (I) and (V) leads to formation of symmetrical bis(indolyl)acetamides (II) and (VI), resp., while electrophilic substitution of indoles (III) and (VII) with indolylacetamides (I) give rise to unsymmetrical bis(indolyl)acetamides (IV) and (VIII).
ChemInform Abstract: Catalytic Enantioselective C—H Functionalization of Indoles with α‐Diazopropionates Using Chiral Dirhodium(II) Carboxylates: Asymmetric Synthesis of the (+)‐α‐Methyl‐3‐indolylacetic Acid Fragment of Acremoauxin A.
Authors: Goto Takayuki , Natori Yoshihiro , Takeda Koji , Nambu Hisanori , Hashimoto Shunichi
Published: November 2011

The title reaction provides a variety of N‐Mom‐protected α‐methyl‐3‐indolylacetates (III) in moderate enantioselectivities up to 86%.
ChemInform Abstract: Synthesis of Substituted 1,4,5,6‐Tetrahydrocyclopenta[b]pyrroles by Platinum‐Catalyzed Cascade Cyclization/Ring Expansion of 2‐Alkynyl‐1‐azaspiro[2.3]hexanes.
Authors: Yoshida Masahiro , Maeyama Yohei , Al‐Amin Mohammad , Shishido Kozo
Published: November 2011

Tetrahydroindoles like (XIV) are also available.
ChemInform Abstract: Tandem Indole C—H Alkenylation/Arylation for Tetra‐Substituted Alkene Synthesis.
Authors: Lopez Suarez Laura , Greaney Michael F.
Published: November 2011

Alkynyl indoles such as (I), (IV), (VI) and (VIII) undergo a novel sequence of Pd‐catalyzed indole C—H activation/alkyne carbopalladation/arylation with diaryliodonium salts (II) furnishing the corresponding functionalized indole alkenes (III), (V), (VII) and (IX), resp., in good to high yields.
ChemInform Abstract: An Unexpected Result from the Reaction of Hydroxymethyl‐2‐oxazolidinones with Isocyanates.
Authors: Madesclaire M. , Leal F. , Weber V. , Decombat C. , Zaitsev V. P. , Zaitseva J. V.
Published: November 2011

Hydroxymethyl‐2‐oxazolidinones can react with aryl isocyanates at both the ring NH and OH‐group, unexpectedly.
ChemInform Abstract: Asymmetric Synthesis of Chiral δ‐Lactones Containing Multiple Contiguous Stereocenters.
Authors: Peed Jennifer , Dominguez Ignacio Perinan , Davies Iwan R. , Cheeseman Matt , Taylor James E. , Kociok‐Koehn Gabriele , Bull Steven D.
Published: November 2011

The cyclopropane ring opening reaction is mediated by Hg(O‐CO‐CF3)2, leads after demetalation to chiral δ‐lactones with multiple stereocenters.
ChemInform Abstract: Palladium‐Mediated Intramolecular Buchwald—Hartwig α‐Arylation of β‐Amino Esters: Synthesis of Functionalized Tetrahydroisoquinolines.
Authors: Reddy A Gopi Krishna , Krishna J. , Satyanarayana G.
Published: November 2011

The three‐step strategy involves reductive amination of aromatic aldehydes, addition of the resulting secondary amines to ethyl acrylate and final Buchwald—Hartwig cyclization.
ChemInform Abstract: Asymmetric Organocatalytic Synthesis of Complex Cyclopenta[b]quinoline Derivatives.
Authors: Jensen Kim L. , Dickmeiss Gustav , Donslund Bjarke S. , Poulsen Pernille H. , Joergensen Karl Anker
Published: November 2011

Various title systems bearing 5 stereogenic centers are prepared with excellent enantioselectivities in a one‐pot manner.
ChemInform Abstract: Synthesis of Furo[2,3‐c]pyridine.
Authors: Chang Meng‐Yang , Tai Hang‐Yi
Published: November 2011

The facile synthesis of furopyridine (VIII) is achieved in five steps from the known piperidinone (I) via Wittig olefination, intramolecular cyclization of (III) by treatment with Ph‐Se‐Cl, NaJO4‐mediated oxidative dehydroselenylation, furan ring formation by reduction, and finally, aromatization.
ChemInform Abstract: Investigating N‐Methoxy‐N′‐aryl Ureas in Oxidative C—H Olefination Reactions: An Unexpected Oxidation Behavior.
Authors: Willwacher Jens , Rakshit Souvik , Glorius Frank
Published: November 2011

Dihydroquinazolinones are prepared from a 2:1 stoichiometric ratio of ureas (I) or (IX) and acrylates or related olefins in the presence of a rhodium catalyst.
ChemInform Abstract: Three‐Component Tandem Reaction Involving Acid Chlorides, Terminal Alkynes, and Ethyl 2‐Amino‐1H‐indole‐3‐carboxylates: Synthesis of Highly Diversified Pyrimido[1,2‐a]indoles via Sequential Sonogashira and [3 + 3] Cyclocondensation Reactions.
Authors: Gupta Sahaj , Sharma Sudhir K. , Mandadapu Anil K. , Gauniyal Harsh M. , Kundu Bijoy
Published: November 2011

Alkynone formation according to A) is followed by cyclocondensation according to B) to produce the heterocyclic system (IV)(18 examples).
ChemInform Abstract: A Practical Synthesis of Novel Rho‐Kinase Inhibitor, (S)‐4‐Fluoro‐5‐(2‐methyl‐1,4‐diazepan‐1‐ylsulfonyl)isoquinoline.
Authors: Gomi Noriaki , Ohgiya Tadaaki , Shibuya Kimiyuki , Katsuyama Jyunji , Masumoto Masayuki , Sakai Hitoshi
Published: November 2011

The synthesis of the novel inhibitor (VII) is achieved in multi‐kilogram scale overcoming two major issues: the need of developing a regioselective chlorosulfonylation reaction at C‐5 of fluoroisoquinoline and the stereochemical purity in the asymmetric construction of the methyldiazepane moiety.
ChemInform Abstract: Directed ortho‐Metalation—Cross Coupling Strategies. One‐Pot Suzuki Reaction to Biaryl and Heterobiaryl Sulfonamides.
Authors: Schneider Cedric , Broda Ellen , Snieckus Victor
Published: November 2011

The method is developed to prepare ortho‐boropinacolato aryl‐ and heteroaryl sulfonamides which can be used directly in one‐pot Suzuki couplings with aryl‐ and heteroaryl halides.
ChemInform Abstract: Ultrasound‐Assisted One‐Pot Synthesis of α‐Oxycarbanilinophosphonates via a Three‐Component Condensation of an Aldehyde, Diethyl Phosphite and an Isocyanate under Solvent‐Free Conditions.
Authors: Kaboudin Babak , Fallahi Maryam
Published: November 2011

The preparation of the synthetically important phosphonates becomes possible under mild conditions and no tar formation is observed.
ChemInform Abstract: A New Series of 2‐Alkoxy(aralkoxy)‐[1,2,4]triazolo[1,5‐a]quinazolin‐5‐ones as Adenosine Receptor Antagonists.
Authors: Al‐Salahi Rashad , Geffken Detlef , Koellner Maria
Published: November 2011

All compounds (I)‐(IV) are tested for their affinity at the adenosine receptor subtypes A1, A2A, and A2B.
ChemInform Abstract: Cluster Structure and Reactions: Gaining Insights into Catalytic Processes
Authors: Castleman, A. W. Jr.
Published: November 2011

Review: 77 refs.
ChemInform Abstract: Ion and Molecular Recognition by Lower Rim 1,3‐Di‐conjugates of Calix[4]arene as Receptors
Authors: Joseph Roymon , Rao Chebrolu Pulla
Published: November 2011

Review: 281 refs.
ChemInform Abstract: The Cope Rearrangement — The First Born of a Great Family
Authors: Graulich Nicole
Published: November 2011

Review: 124 refs.
ChemInform Abstract: Five‐Membered Oxaza Heterocyclic Compounds on the Basis of Epoxides and Aziridines
Authors: Kas'yan L. I. , Pal'chikov V. A. , Bondarenko Ya. S.
Published: November 2011

Review: 254 refs.
ChemInform Abstract: Metal‐Catalyzed Approaches to Amide Bond Formation
Authors: Allen C. Liana , Williams Jonathan M. J.
Published: November 2011

Review: 76 refs.
ChemInform Abstract: De novo Designed Peptides for Biological Applications
Authors: Boyle Aimee L. , Woolfson Derek N.
Published: November 2011

Review: 67 refs.
ChemInform Abstract: Bromination of Deactivated Aromatic Compounds
Authors: Andrievsky A. M. , Gorelik M. V.
Published: November 2011

Review: 71 refs.
ChemInform Abstract: Thiophosphinic Acids: Historic Overview and Recent Advances in Their Synthesis and Applications
Authors: Vassiliou Stamatia
Published: November 2011

Review: 43 refs.
ChemInform Abstract: Synthesis of Schiff′s Bases of 2‐Amino‐4‐phenylthiazole
Authors: Avanish Kumar , Rajesh Kumar
Published: November 2011

Review: 9 refs.
ChemInform Abstract: Organocatalytic Enantioselective Henry Reactions
Authors: Alvarez‐Casao Yolanda , Marques‐Lopez Eugenia , Herrera Raquel P.
Published: November 2011

Review: 62 refs.
ChemInform Abstract: Role of Chemical Kinetics in the Heterogeneous Catalysis Studies
Authors: Petrov L. A. , Alhamed Y. , Al‐Zahrani A. , Daous M.
Published: November 2011

Review: 131 refs.
Microstructures for the Catalytic Hydrogen Generation from Ethanol
Authors: Ehrich Heike , Jähnisch Klaus
Published: November 2011

Wasserstoff für Brennstoffzellensysteme wurde durch katalytische Wasserdampfreformierung von Ethanol in Mikrostrukturreaktoren erzeugt. Der Einfluss der Reaktionstemperatur, der Kontaktzeit und des molaren Steam/Carbon‐Verhältnisses (S/C) auf die Reaktion wurde untersucht. Der auf der Mikrostruktur beschichtete Co/ZnO‐Katalysator zeigte eine hohe Aktivität und Selektivität, die Wasserstoffausbeute betrug bis zu 5,2 mol mol–1 Ethanol. Ethanol wurde bei kurzer Kontaktzeit (W/F 25 g min mol–1) und 600 °C bei S/C‐Verhältnissen von 4,9 bis 6,5 vollständig umgesetzt.
A performance evaluation framework for packet scheduling algorithms in wireless system
Authors: Zhao X. , Liang H.
Published: November 2011

The question of how to evaluate wireless packet scheduling algorithms with a comprehensive consideration of different performance metrics is investigated in this paper. By studying the intrinsic relationship between system throughput and fairness, a performance evaluation problem for packet scheduling algorithms in a wireless system is formulated. Through the use of nonlinear programming method, the performance evaluation framework for weighted‐type packet scheduling algorithms can be established. The performances of some typical packet scheduling algorithms for multiuser wireless communications are also evaluated in this framework as examples. Copyright © 2011 John Wiley & Sons, Ltd.
CD304 is preferentially expressed on a subset of B‐lineage acute lymphoblastic leukemia and represents a novel marker for minimal residual disease detection by flow cytometry
Authors: Solly Françoise , Angelot Fanny , Garand Richard , Ferrand Christophe , Seillès Estelle , Schillinger Françoise , Decobecq Agnès , Billot Maryse , Larosa Fabrice , Plouvier Emmanuel , Deconinck Eric , Legrand Faezeh , Saas Philippe , Rohrlich Pierre‐Simon , Garnache‐Ottou Francine
Published: November 2011

Minimal residual disease (MRD) has emerged as a major prognostic factor for monitoring patients with B‐lineage acute lymphoblastic leukemia (B‐ALL). The quantification of MRD by flow cytometry (FC) is based on the identification of a leukemia‐associated phenotype (LAP). Because phenotypic switch is common during treatment, multiple LAPs must be available and used for MRD detection over time. We evaluated the potential usefulness of CD304 as a new marker for monitoring MRD. CD304 was expressed in 48% of B‐ALL (24/50) with discriminative fluorescence intensity compared with CD304‐negative normal B‐cell precursors (n = 15). The sensitivity of CD304‐based MRD detection reached 10−4, as with some of established LAPs. The stability of CD304 expression evaluated during therapy and at relapse confirms the usefulness of this marker for MRD quantification. Finally, CD304 was repeatedly expressed in patients with TEL‐AML1 gene rearrangement, which warrants further investigation on its potential relevance as a prognosis marker or therapeutic target. © 2011 International Society for Advancement of Cytometry
Relaxor Behavior in a New Aurivillius Oxide – Bi2La0.5Sr0.5Nb1.75Sc0.25O9
Authors: Sivakumar Thathan , Itoh Mitsuru
Published: November 2011

A new relaxor type n = 2 Aurivillius oxide material,Bi2La0.5Sr0.5Nb1.75Sc0.25O9 (I), containing heterovalent A and B site cations was synthesized by standard solid‐state reaction. The crystal structure of I was determined by Rietveld refinement of the powder X‐ray diffraction data in the polar A21am space group [a = 5.5152(5) Å, b = 5.5199(5) Å, c = 25.1982(12) Å; V = 767.12(10) Å3] at room temperature. Dielectric measurements for I reveal broad dielectric maxima that shift to higher temperature with increasing frequency. The dielectric maximum temperature (Tmax) at 100 kHz for I is 468 K, which is higher than that of the well‐known relaxor type Aurivillius oxide BaBi2Ta2O9. The relaxation parameter (γ), obtained from a modified Curie–Weiss law for I, is 1.91. The piezoelectric coefficient (d33) and remanent polarization (Pr) for the poled sample of I are 3 pC/N and 5.7 μC/cm2, respectively.