bluuebunny/crossref_metadata_2025_split huggingface dataset:
An In‐Mediated Tandem Reaction of Aldehydes with 3‐Bromo‐1‐propyne To Produce 1‐Substituted‐3‐methylene‐5‐yn‐1‐ol Compounds
Authors: Huang Jing‐Mei , Luo Hui‐Chao , Chen Zu‐Xing , Yang Gui‐Chun , Loh Teck‐Peng 
Published: November 2007

AbstractA one‐pot reaction for the synthesis of 1‐substituted‐3‐methylene‐5‐yn‐1‐ol compounds from In‐mediated propargylation of aldehydes with 3‐bromo‐1‐propyne was reported. Our studies showed that the propargylic alcohol formed in the reaction was selectively subjected to further propargylation of the triple bond to afford the Markovnikov addition products in a regiospecific fashion.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Versatile Synthesis of Free and N‐Benzyloxycarbonyl‐Protected 2,2‐Disubstituted Taurines
Authors: Wang Boyuan , Zhang Wei , Zhang Leilei , Du Da‐Ming , Liu Gang , Xu Jiaxi 
Published: November 2007

AbstractAn effective and versatile method was developed to synthesize N‐benzyloxycarbonyl‐protected and free 2,2‐disubstituted taurines. Several novel 2,2‐disubstituted taurines, including aliphatic/aromatic and cyclic/acyclic derivatives, were obtained, which demonstrates the generality of this method. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Chiral Tertiary Amine/L‐Proline Cocatalyzed Enantioselective Morita–Baylis–Hillman (MBH) Reaction
Authors: Tang Hongying , Zhao Guofeng , Zhou Zhenghong , Gao Peng , He Liangnian , Tang Chuchi 
Published: November 2007

AbstractFour types of chiral amines have been synthesized starting from readily available chiral sources. These chiral amines in combination with L‐proline have been found to be efficient cocatalysts for the asymmetric Morita–Baylis–Hillman (MBH) reaction between methyl vinyl ketone (MVK) and aromatic aldehydes. The corresponding adducts were formed in reasonable chemical yields and with good enantioselectivities (up to 83 % ee). Moreover, parallel cocatalytic reactions with the two enantiomers of chiral amine 4 and L‐proline revealed that it is the proline stereochemistry that determines the configuration of the newly formed chiral center. In addition, the existence of the free hydroxy group in amine 4a enhanced the enantioselectivity of the reaction. Based on these findings, a plausible mechanism for this cocatalytic MBH reaction has been proposed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Cavity‐Extended Inherently Chiral Resorcin[4]arenes: Synthesis and Chiroptical Properties of the Cycloenantiomers
Authors: Paletta Marlene , Klaes Michael , Neumann Beate , Stammler Hans‐Georg , Grimme Stefan , Mattay Jochen 
Published: November 2007

AbstractInherently chiral resorcin[4]arenes 2 and 3 were prepared from enantiomerically pure C4‐symmetric rccc‐2,8,14,20‐tetraisobutyl‐4,10,16,22‐tetra‐O‐methylresorcin[4]arene (1). The four 2‐bromobenzyl ether residues in precursor 2 were introduced as halide moieties to partake in an intramolecular Pd‐catalysed C–C cross‐coupling reaction to give tetrabiaryl ether compound 3. The absolute configurations could be derived from the starting compounds and were assigned as (M,R)‐(–)‐2 and (P,S)‐(+)‐2 for the tetrakis(2′‐bromobenzyl) ether compounds as well as (M,R)‐(–)‐3 and (P,S)‐(+)‐3 for the cavity‐extended resorcinarenes. The carbon scaffold of 3 contains four new stereogenic axes whose configurations were assigned by single‐crystal X‐ray analysis. The simulation of the CD spectra by time‐dependent Pariser–Parr–Pople calculations (TDPPP) based on the X‐ray data gave very good images of the experimental spectra. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A New Approach to the Total Synthesis of Rosuvastatin
Authors: Andrushko Natalia , Andrushko Vasyl , König Gerd , Spannenberg Anke , Börner Armin 
Published: November 2007

AbstractA new multi‐step synthesis of the lipid‐lowering agent rosuvastatin, involving two homogeneously catalyzed reaction steps, is described. The key building block, N‐[4‐(4‐fluorophenyl)‐5‐formyl‐6‐isopropylpyrimidin‐2‐yl]‐N‐methylmethanesulfonamide (2), was prepared by Pd‐catalyzed formylation with CO/H2 (1:1, 50 bar, phosphane ligand/substrate ratio of 1:10). Several alternative pathways for the preparation of 2 were also tested, but were found to be inferior. Rosuvastatin precursor 1 was assembled by Wittig coupling of aldehyde 2 and ylide (R)‐3, derived from a Ru‐catalyzed asymmetric hydrogenation. The second stereogenic center was finally created by stereoselective reduction with Et2BOMe and NaBH4 to afford rosuvastatin ethyl ester. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Straightforward Protocol for the Solution‐Phase Parallel Synthesis of Ceramide Analogues
Authors: Grijalvo Santiago , Matabosch Xavier , Llebaria Amadeu , Delgado Antonio 
Published: November 2007

AbstractA simple solution‐phase protocol for the synthesis of ceramide analogues from easily accessible enantiopure scaffolds is disclosed. The method relies on the use of nucleophilic thiolates or phenoxides and appropriate supported reagents or scavengers to give the target compounds in good overall yields. The method is easily adaptable to combinatorial protocols and also amenable to automated processes for the generation of small‐to‐medium‐sized libraries for further screening.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Bis(diamido)‐Bridged Basket Resorcin[4]arenes as Enantioselective Receptors for Amino Acids and Amines
Authors: Botta Bruno , D'Acquarica Ilaria , Nevola Laura , Sacco Fabiola , Lopez Zara Valbuena , Zappia Giovanni , Fraschetti Caterina , Speranza Maurizio , Tafi Andrea , Caporuscio Fabiana , Letzel Matthias C. , Mattay Jochen 
Published: November 2007

AbstractOn the research avenue opened by the rigidified double‐spanned resorcin[4]arene 1, we have synthesized both enantiomers of the two chiral basket resorcin[4]arenes 3 and 4, each containing two 1,2‐diaminocyclohexane and 1,2‐diphenylethylenediamine bridges, respectively. In the new compounds, the aromatic rims assume the expected flattened cone arrangement, whereas two different conformations, tentatively designated as “open wings” and “folded wings”, were attributed to the bridge substituents according to molecular modeling studies. In MSn (ESI) experiments, the proton‐bonded diastereomeric [4·H·A]+ complexes with amino acidic guests (A) exhibited a pronounced selectivity towards the enantiomers of tyrosine methyl ester (tyrOMe) and amphetamine (amph), whereas the chirality of tryptophan (trp) was ineffective. Moreover, a kinetic study on the base‐induced displacement of the guest revealed that the L‐tyrOMe (and L‐amph) enantiomer is faster displaced from the heterochiral [4·H·L‐tyrOMe]+ (or [ent‐4·H·l‐amph]+) complex than from the homochiral [ent‐4·H·L‐tyrOMe]+ (or [4·H·l‐amph]+) one. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Improved Auxiliary for the Synthesis of Medium‐Sized Bis(lactams)
Authors: Springer Jasper , Jansen T. Paul , Ingemann Steen , Hiemstra Henk , van Maarseveen Jan H. 
Published: November 2007

AbstractOur auxiliary‐based method for the synthesis of bis(lactams) has been optimized. A novel auxiliary is described that is inserted in the backbone of a linear peptide facilitating the mutually reactive terminal groups to approach one another for a cyclization reaction. A subsequent ring contraction mechanism leads to the bis(lactams) with the remainings of the auxiliary still attached. Functionalized seven‐ and eight‐membered bis(lactams) have been prepared that are difficult to access using traditional methods. Removal of the auxiliary from the bis(lactams) has been described with the possible side reactions that can occur.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Catalysis by Ionic Liquids: Significant Rate Acceleration with the Use of [pmIm]Br in the Three‐Component Synthesis of Dithio­carbamates
Authors: Ranu Brindaban C. , Saha Amit , Banerjee Subhash 
Published: November 2007

AbstractAn easily accessible neutral ionic liquid, 1‐methyl‐3‐pentylimidazolium bromide, promoted a one‐pot three‐component condensation of an amine, carbon disulfide, and an activated alkene/dichloromethane/epoxide to produce the corresponding dithiocarbamates in high yields at room temperature. The reactions are very fast in ionic liquids relative to those in other reaction media. These reactions do not require any additional catalyst or solvent. The ionic liquid can be recovered and recycled for subsequent reactions. A plausible mechanism is suggested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Effect of Varying the Anionic Component of a Copper(I) Catalyst on Homologation of Arylacetylenes to Allenes by the Mannich Reaction
Authors: Kumar Vipan , Chipeleme Alex , Chibale Kelly 
Published: November 2007

AbstractThe effect of varying the anionic component of a copper(I) catalyst in the homologation of terminal arylacetylenes to allenes by the Mannich reaction was investigated. Varying amounts of allenes, Mannich bases and dimers were obtained depending on the nature of the anionic component of the copper catalyst. On the other hand, Eglinton–Glaser dimerizations were achieved in high yields with 0.5 equiv. of triethylamine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis and Rearrangement of Dewar Benzenes Into Biaryls: Experimental Evidence for Conrotatory Ring Opening
Authors: Janková Štěpánka , Dračínský Martin , Císařová Ivana , Kotora Martin 
Published: November 2007

AbstractRearrangement of aryl‐substituted Dewar benzenes into the corresponding biaryls may serve as an alternative pathway for synthesis of sterically hindered biaryls. The kinetic data obtained from thermal rearrangements of Dewar benzenes provide experimental evidence for the proposed orbital‐symmetry‐controlled electrocyclic ring opening. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Cationic P(OPh)3‐ or PPh3‐Rhodium(I) Complex‐Catalyzed Isomerizations of 5‐Alkynals to δ‐Alkynyl Ketones, Cyclopent‐1‐enyl Ketones, and Cyclohexenones (Eur. J. Org. Chem. 34/2007)
Authors: Tanaka Ken , Sasaki Kaori , Takeishi Kenzo , Hirano Masao 
Published: November 2007

AbstractThe cover picture shows the cationic rhodium(I) complex catalyzed isomerization of 5‐alkynals to four different types of ketones. The catalytic isomerization of 5‐alkynals to δ‐alkynyl ketones and cyclopent‐1‐enyl ketones proceeds by using RhI+/P(OPh)3, whereas the catalytic endo/trans and exo/cis hydroacylation of 5‐alkynals to cyclohexenones and cyclopentanones proceeds by using RhI+/PPh3 and RhI+/BINAP, respectively. The ligands of the Rh catalysts and the substituents at the 4‐position of the 5‐alkynals play an important role in determining which isomerization product results. Details are discussed in the article by K. Tanaka et al. on p. 5675 ff.
A risk‐based approach for bidding strategy in an electricity pay‐as‐bid auction
Authors: Sadeh Javad , Mashhadi Habib Rajabi , Latifi Mohammad Amin 
Published: November 2007

AbstractWith the reform of electric power industry and the development of electrical energy markets in many countries, it is of significance to develop bidding strategies for generation companies (GenCos). In this environment, one of the most challenging and important tasks for a GenCo is developing effective strategies to optimize hourly offer curve. In this paper, focusing on Iran's electricity market structure, we model the bidding problem from the viewpoint of a GenCo in a pay‐as‐bid (PAB) auction. Our goal is to present a tool for determining the optimal bidding strategy of a price‐taker producer in an electricity PAB auction taking into account the relevant risks. Due to uncertainties in power market, the market‐clearing price (MCP) of each hour is assumed to be known as a probability density function (pdf). The optimal solution of bidding problem is obtained analytically based on the classical optimization theory. Also, the analytical solution for a multi‐step bid protocol is generalized and the properties of the generalized solution are discussed. A model is developed to consider concept of risk using two different methods. The two proposed methods are then compared and the results interpreted using numerical examples. In addition, the effect of variation of MCP's pdf parameters on supplier's profit is studied. Copyright © 2007 John Wiley & Sons, Ltd.
Directional functional coupling of cerebral rhythms between anterior cingulate and dorsolateral prefrontal areas during rare stimuli: A directed transfer function analysis of human depth EEG signal
Authors: Brázdil Milan , Babiloni Claudio , Roman Robert , Daniel Pavel , Bareš Martin , Rektor Ivan , Eusebi Fabrizio , Rossini Paolo Maria , Vecchio Fabrizio 
Published: November 2007

AbstractWhat is the neural substrate of our capability to properly react to changes in the environment? It can be hypothesized that the anterior cingulate cortex (ACC) manages repetitive stimuli in routine conditions and alerts the dorsolateral prefrontal cortex (PFC) when stimulation unexpectedly changes. To provide evidence in favor of this hypothesis, intracerebral stereoelectroencephalographic (SEEG) data were recorded from the anterior cingulate and dorsolateral PFC of eight epileptic patients in a standard visual oddball task during presurgical monitoring. Two types of stimuli (200 ms duration) such as the letters O (frequent stimuli; 80% of probability) and X (rare stimuli) were presented in random order, with an interstimulus interval between 2 and 5 s. Subjects had to mentally count the rare (target) stimuli and to press a button with their dominant hand as quickly and accurately as possible. EEG frequency bands of interest were θ (4–8 Hz), α (8–12 Hz), β (14–30 Hz), and γ (30–45 Hz). The directionality of the information flux within the EEG rhythms was indexed by a directed transfer function (DTF). The results showed that compared with the frequent stimuli, the target stimuli induced a statistically significant increase of DTF values from the anterior cingulate to the dorsolateral PFC at the θ rhythms (P < 0.01). These results provide support to the hypothesis that ACC directly or indirectly affects the oscillatory activity of dorsolateral PFC by a selective frequency code under typical oddball conditions. Hum Brain Mapp 2009. © 2007 Wiley‐Liss, Inc.
A stromal gene signature associated with inflammatory breast cancer
Authors: Boersma Brenda J. , Reimers Mark , Yi Ming , Ludwig Joseph A. , Luke Brian T. , Stephens Robert M. , Yfantis Harry G. , Lee Dong H. , Weinstein John N. , Ambs Stefan 
Published: November 2007

AbstractThe factors that determine whether a breast carcinoma will develop into inflammatory breast cancer (IBC) remain poorly understood. Recent evidence indicates that the tumor stroma influences cancer phenotypes. We tested the hypotheses that the gene expression signature of the tumor stroma is a distinctive feature of IBC. We used laser capture microdissection to obtain enriched populations of tumor epithelial cells and adjacent stromal cells from 15 patients with IBC and 35 patients with invasive, noninflammatory breast cancer (non‐IBC). Their mRNA expression profiles were assessed using Affymetrix GeneChips™. In addition, a previously established classifier for IBC was evaluated for the resulting data sets. The gene expression profile of the tumor stroma distinguished IBC from non‐IBC, and a previously established IBC prediction signature performed better in classifying IBC using the gene expression profile of the tumor stroma than it did using the profile of the tumor epithelium. In a pathway analysis, the genes differentially expressed between IBC and non‐IBC tumors clustered in distinct pathways. We identified multiple pathways related to the endoplasmic stress response that could be functionally significant in IBC. Our findings suggest that the gene expression in the tumor stroma may play a role in determining the IBC phenotype. © 2007 Wiley‐Liss, Inc.
Differential sensitivity of human colon cancer cell lines to the nucleoside analogs ARC and DRB
Authors: Bhat Uppoor G. , Gartel Andrei L. 
Published: November 2007

AbstractRecently, we identified a nucleoside analog named ARC (4‐amino‐6‐hydrazino‐7‐β‐D‐ribofuranosyl‐7H‐Pyrrolo[2,3‐d]pyrimidine‐5‐carboxamide), which has the properties of a general transcriptional inhibitor. Here, we report the characterization of ARC on a panel of colorectal cancer (CRC) cell lines. Cell death induced by ARC in CRC cells was accompanied by caspase‐3 cleavage and correlated with the downregulation of antiapoptotic proteins, survivin and Mcl‐1 and with the inhibition of Akt phosphorylation. At the same time, colon cancer cell lines were resistant to the well–known nucleoside analog DRB (5,6‐dichloro‐1‐β‐D‐ribofuranosylbenzimidazole), which failed to downregulate Mcl‐1 or survivin. Overall, ARC could represent an attractive candidate for anti‐cancer drug development that targets multiple survival pathways in colon cancer cells. © 2007 Wiley‐Liss, Inc.
Extracellular matrix and HIF‐1 signaling: The role of prolidase
Authors: Surazynski Arkadiusz , Donald Steven P. , Cooper Sandra K. , Whiteside Martin A. , Salnikow Konstantin , Liu Yongmin , Phang James M. 
Published: November 2007

AbstractHypoxia‐inducible factor‐1 (HIF‐1) plays an important role in stress‐responsive gene expression. Although primarily sensitive to hypoxia, HIF‐1 signaling can be regulated by a number of stress factors including metabolic stress, growth factors and molecules present in the extracellular matrix (ECM). Degradation of ECM by metalloproteinases (MMP) is important for tumor progression, invasion and metastasis. ECM is predominantly collagen, and the imino acids (Pro and HyPro) comprise 25% of collagen residues. The final step in collagen degradation is catalyzed by prolidase, the obligate peptidase for imidodipeptides with Pro and HyPro in the carboxyl terminus. Defective wound healing in patients with inherited prolidase deficiency is associated with histologic features of angiopathy suggesting that prolidase may play a role in angiogenesis. Because HIF‐1α is central to angiogenesis, we considered that prolidase may modulate this pathway. To test this hypothesis, we made expression constructs of human prolidase and obtained stable transfectants in colorectal cancer cells (RKO). Overexpression of prolidase resulted in increased nuclear hypoxia inducible factor (HIF‐1α) levels and elevated expression of HIF‐1−dependent gene products, vascular endothelial growth factor (VEGF) and glucose transporter‐1 (Glut‐1). The activation of HIF‐1‐dependent transcription was shown by prolidase‐dependent activation of hypoxia response element (HRE)‐luciferase expression. We used an oxygen‐dependent degradation domain (ODD)‐luciferase reporter construct as a surrogate for HIF‐1α as an in situ prolyl‐hydroxylase assay. Since this reporter is degraded by VHL‐dependent mechanisms, the increased levels of luciferase observed with prolidase expression reflected the decreased HIF‐1α prolyl hydroxylase activity. Additionally, the differential expression of prolidase in 2 breast cancer cell lines showed prolidase‐dependent differences in HIF‐1α levels. These findings show that metabolism of imidodipeptides by prolidase plays a previously unrecognized role in angiogenic signaling. © 2007 Wiley‐Liss, Inc.
Biophysical Response to Pulsed Laser Microbeam‐Induced Cell Lysis and Molecular Delivery
Authors: Hellman Amy N. , Rau Kaustubh R. , Yoon Helen H. , Venugopalan Vasan 
Published: November 2007

AbstractCell lysis and molecular delivery in confluent monolayers of PtK2 cells are achieved by the delivery of 6 ns, λ = 532 nm laser pulses via a 40×, 0.8 NA microscope objective. With increasing distance from the point of laser focus we find regions of (a) immediate cell lysis; (b) necrotic cells that detach during the fluorescence assays; (c) permeabilized cells sufficient to facilitate the uptake of small (3 kDa) FITC‐conjugated Dextran molecules in viable cells; and (d) unaffected, viable cells. The spatial extent of cell lysis, cell detachment, and molecular delivery increased with laser pulse energy. Hydrodynamic analysis from time‐resolved imaging studies reveal that the maximum wall shear stress associated with the pulsed laser microbeam‐induced cavitation bubble expansion governs the location and spatial extent of each of these regions independent of laser pulse energy. Specifically, cells exposed to maximum wall shear stresses τw, max > 190 ± 20 kPa are immediately lysed while cells exposed to τw, max > 18 ± 2 kPa are necrotic and subsequently detach. Cells exposed to τw, max in the range 8–18 kPa are viable and successfully optoporated with 3 kDa Dextran molecules. Cells exposed to τw, max < 8 ± 1 kPa remain viable without molecular delivery. These findings provide the first direct correlation between pulsed laser microbeam‐induced shear stresses and subsequent cellular outcome. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unified QSAR and network‐based computational chemistry approach to antimicrobials, part 1: Multispecies activity models for antifungals
Authors: GonzÁlez‐DÍaz Humberto , Prado‐Prado Francisco J. 
Published: November 2007

AbstractThere are many pathogen microbial species with very different antimicrobial drugs susceptibility. In this work, we selected pairs of antifungal drugs with similar/dissimilar species predicted‐activity profile and represented it as a large network, which may be used to identify drugs with similar mechanism of action. Computational chemistry prediction of the biological activity based on quantitative structure–activity relationships (QSAR) susbtantially increases the potentialities of this kind of networks, avoiding time and resource‐consuming experiments. Unfortunately, most QSAR models are unspecific or predict activity against only one species. To solve this problem we developed a multispecies QSAR classification model, in which the outputs were the inputs of the aforementioned network. Overall model classification accuracy was 87.0% (161/185 compounds) in training, 83.4% (50/61) in validation, and 83.7% for 288 additional antifungal compounds used to extend model validation for network construction. The network predicted has 59 nodes (compounds), 648 edges (pairs of compounds with similar activity), low coverage density d = 37.8%, and distribution more close to normal than to exponential. These results are more characteristic of a not‐overestimated random network, clustering different drug mechanisms of actions, than of a less useful power law network with few mechanisms (network hubs). © 2007 Wiley Periodicals, Inc. J Comput Chem 2008