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Phase Synthesis (phase + synthesis)
Kinds of Phase Synthesis Selected AbstractsFrom "Parasitic" Association Reactions toward the Stoichiometry Controlled Gas Phase Synthesis of Nanoparticles: A Theoretically Driven Challenge for ExperimentalistsTHE CHEMICAL RECORD, Issue 5 2002Alexey Y. Timoshkin Abstract In the present record a model for the gas-phase reactions during the chemical vapor deposition (CVD) processes of group 13,15 materials is presented, based on the results of extensive quantum-chemical modeling. Thermodynamic criteria have been introduced to evaluate the importance of a range of association reactions. For the organometallic and hydride derivatives, association processes are found to be favorable both thermodynamically and kinetically. Formation of high mass association products takes place under CVD conditions, including laser-assisted CVD. Structural and thermodynamic properties of the most important ring and cluster intermediates have been predicted. The stoichiometry-controlled synthesis of the 13,15 ternary alloys and nanoparticles using cluster compounds as single-source precursors is predicted to be viable. The association pathway described may be generalized to the CVD reactions of many binary materials (12,16, 13,16, 13,15, 14,15, 14,16). © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 319,338, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10037 [source] ChemInform Abstract: Ceric Ammonium Nitrate (CAN) Promoted Efficient Solid Phase Synthesis of Amide Derivatives: A Green Approach.CHEMINFORM, Issue 20 2008Ch. Sanjeeva Reddy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Aqueous Phase Synthesis of Thiazoles and Aminothiazoles in the Presence of ,-Cyclodextrin.CHEMINFORM, Issue 51 2005M. Narender Abstract For Abstract see ChemInform Abstract in Full Text. [source] Modification of the Titanium(IV) Isopropoxide Reductive Amination Reaction: Application to Solid Phase Synthesis.CHEMINFORM, Issue 48 2005John C. DiCesare Abstract For Abstract see ChemInform Abstract in Full Text. [source] Solution Phase Synthesis of Imidazo[1,2-b]pyrazol-2-one, an Interesting 5,5-Fused Heterocyclic Ring System.CHEMINFORM, Issue 17 2004Benjamin E. Blass Abstract For Abstract see ChemInform Abstract in Full Text. [source] Microwave Assisted Solid Phase Synthesis of Pyrimidine Derivatives.CHEMINFORM, Issue 10 2003Mazaahir Kidwai Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: The Mannich Reaction of Hydrazones Amenable to Solid Phase Synthesis: A Powerful Tool for Heterocycle Preparation.CHEMINFORM, Issue 25 2002Valerie Atlan Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Stereodivergent Diversity Oriented Synthesis of Piperidine Alkaloids,,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2006Louis V. Adriaenssens Abstract Alkylidenetitanium reagents enable the reagent-controlled high throughput asymmetric synthesis of 2-substituted piperidines and rapid access to multiple cyclic imines using solid phase synthesis (SPS). The Schrock carbenes, generated by reduction of thioacetals, convert resin-bound esters into enol ethers. Treatment with acid releases amino ketones that are cyclized with TMSCl to give iminium salts. Reduction introduces a chiral centre at C-2, whose absolute stereochemistry is determined by a phenethylamine (PEA) chiral auxiliary. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Kinetics of liquid phase synthesis of ethyl tert -butyl ether from tert -butyl alcohol and ethanol catalyzed by ,-zeolite supported on monolithINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2002S. Assabumrungrat This paper compared the performance of ,-zeolite and Amberlyst-15 catalysts on a liquid phase synthesis of ethyl tert -butyl ether (ETBE) from ethanol (EtOH) and tert -butyl alcohol (TBA) ,-Zeolite was synthesized and deposited on monolith support. Its structure was confirmed by an XRD measurement and its composition was analyzed by an XRF measurement. It was found that even though the catalytic activity of ,-zeolite was lower than that of Amberlyst-15, the selectivity of ETBE was much higher than that of Amberlyst-15, resulting in almost the same level of ETBE yield. The dehydration of TBA to isobutene (IB) was the major side reaction. The kinetic study of the reaction catalyzed by ,-zeolite supported on monolith was carried out by using a semibatch reactor. The effect of external mass transfer was investigated by varying stirring speeds. The activity-based rate expressions were developed taking into account of water inhibition. Three temperature levels of 323, 333, and 343 K were performed in the study to obtain the parameters in the Arrhenius's equation and the Van't Hoff's equation. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 292,299, 2002 [source] New technologies for chemical geneticsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue S37 2001Leslie A. Walling Abstract Chemical genetics, in which small molecules are used in lieu of mutations to study biological processes, requires large and diverse chemical libraries to specifically perturb different biological pathways. Here we describe a suite of technologies that enable chemical libraries prepared by split-pool solid phase synthesis to be screened in a diverse range of chemical genetic assays. Compounds are synthesized on 500 micron high-capacity polystyrene beads, and arrayed into individual wells of 384-well plates using a hand-held bead arrayer. Compounds are cleaved from synthesis beads using a chemically-resistant ceramic dispensing system, producing individual stock solutions of single compounds. Nanoliter volumes of these solutions are then transferred into assay plates using an array of stainless steel pins mounted on a robotic arm. We have designed reusable 1536- and 6144-well assay plates made of silicone rubber that can be cast in the laboratory and filled by hand. This integrated technology platform enables hundreds of biological assays to be performed from the product of a single synthesis bead, enabling the results of different chemical genetic experiments to be directly compared. J. Cell. Biochem. Suppl. 37: 7,12, 2001. © 2002 Wiley-Liss, Inc. [source] Properties and applications of supports for enzyme-mediated transformations in solid phase synthesisJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2006Alessandra Basso Abstract With the increasing interest in automated synthesis and screening protocols, solid supported chemistry and biochemistry have become attractive technologies. Furthermore, the use of enzymes in solid phase synthesis has opened the route to selective and mild processes. The efficiency of enzymes in transforming substrates that are bound on solid supports is strictly related to the availability of polymers endowed with specific properties, above all permeability to enzymes. This review describes how the recent developments of this rapidly evolving area have made possible novel challenging applications of enzymes in solid phase synthesis. Copyright © 2006 Society of Chemical Industry [source] Synthesis of A,[1-42] and its derivatives with improved efficiencyJOURNAL OF PEPTIDE SCIENCE, Issue 2 2007Márta Zarándi Abstract It has been proved that the principal component of senile plaques is aggregates of ,-amyloid peptide (A,) in cases of one of the most common forms of age-related neurodegenerative disorders, Alzheimer's disease (AD). Although the synthetic methods for the synthesis of A, peptides have been developed since their first syntheses, A,[1-42] is still problematic to prepare. The highly hydrophobic composition of A,[1-42] results in aggregation between resin-bound peptide chains or intrachain aggregation which leads to a decrease in the rates of deprotection and repetitive incomplete coupling reactions during 9-flurenylmethoxycarbonyl (Fmoc) synthesis. In order to avoid aggregation and/or disrupt internal aggregation during stepwise Fmoc solid phase synthesis and to improve the quality of crude products, several attempts have been made. Since highly pure A, peptides in large quantities are used in biological experiments, we wanted to develop a method for a rational synthesis of human A,[1-42] with high purity and adequate yield. This paper reports a convenient methodology with a novel solvent system for the synthesis of A,[1-42], its N -terminally truncated derivatives A,[4-42] and A,[5-42], and A,[1-42] labeled with 7-amino-4-methyl-3-coumarinylacetic acid (AMCA) at the N -terminus using Fmoc strategy. The use of 10% anisole in Dimethylformamide/Dichloromethane (DMF/DCM) can substantially improve the purity and yield of crude A,[1-42] and has been shown to be an optimal coupling condition for the synthesis of A,[1-42]. Anisole is a cheap and simple aid in the synthesis of ,difficult sequences' where other solvents are less successful in the prevention of aggregation during the synthesis. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis and biological characterization of human monocyte chemoattractant protein 1 (MCP-1) and its analogsJOURNAL OF PEPTIDE SCIENCE, Issue 1 2006Marian Kruszynski Abstract Novel analogs of human monocyte chemoattractant protein 1 (MCP-1) were designed, synthesized and characterized to be used as tools to generate monoclonal antibodies as potential human therapeutics. MCP-1 and three analogs were synthesized by step-wise Fmoc solid phase synthesis. After oxidation to form the two-disulfide bonds, affinity chromatography using an immobilized mouse anti-human MCP-1 monoclonal antibody (mAb) was utilized for a simple and highly effective purification procedure for the proteins. The final products were extensively characterized and compared with recombinant human MCP-1 (rhMCP-1). All proteins showed identical binding with mouse anti-human MCP-1 mAbs as measured by surface plasmon resonance. Synthetic MCP-1 and the analogs were comparable to recombinant MCP-1 in competition radio-ligand binding to CCR2 receptors on THP-1 cells, and MCP-1-induced, calcium mobilization and chemotaxis assays. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Progress in the preparation of peptide aldehydes via polymer supported IBX oxidation and scavenging by threonyl resin,JOURNAL OF PEPTIDE SCIENCE, Issue 3 2005Gerhard Sorg Abstract Peptide aldehydes are of interest due to their inhibitory properties toward numerous classes of proteolytic enzymes such as caspases or the proteasome. A novel access to peptide aldehydes is described using a combination of solid phase peptide synthesis with polymer-assisted solution phase synthesis based on the oxidation of peptide alcohols with a mild and selective polymer-bound IBX derivative. The oxidation is followed by selective purification via scavenging the peptide aldehyde in a capture-release procedure using threonine attached to an aminomethyl resin. Peptide aldehydes are obtained in excellent purity and satisfying yield. The optical integrity of the C -terminal residue is conserved in a high degree. The procedures are compatible with the use of common side-chain protecting groups. The potential for using the method in parallel approaches is very advantageous. A small collection of new and known peptide aldehydes has been tested for inhibitory activity against caspases 1 and 3. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd. [source] Expediting the Fmoc solid phase synthesis of long peptides through the application of dimethyloxazolidine dipeptidesJOURNAL OF PEPTIDE SCIENCE, Issue 1 2004Dr Peter White Abstract This paper describes the step-wise Fmoc solid phase synthesis of a 95-residue peptide related to FAS death domain. Attempts to prepare this peptide employing conventional amino acid building blocks failed. However, by the judicious use of dimethyloxazolidine dipeptides of serine and threonine, the peptide could be readily prepared in remarkable purity by applying single 1 h coupling reactions. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] The fluorenylmethoxycarbonyl group in solid phase synthesisJOURNAL OF PEPTIDE SCIENCE, Issue 9 2003Robert Sheppard Abstract The history of the fluorenylmethoxycarbonyl amino-protecting group since its introduction into solid phase peptide synthesis in 1978 is briefly traced. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Comparative evaluation of four trityl-type amidomethyl polystyrene resins in Fmoc solid phase peptide synthesisJOURNAL OF PEPTIDE SCIENCE, Issue 7 2003Christos Zikos Abstract Four trityl-type (i.e. non-substituted trityl-, o-Cl-trityl-, o-F-trityl- and p-CN-trityl-) amidomethyl polystyrene resins were evaluated comparatively, in terms of the stability of the trityl-ester bond in slightly acidic dichloromethane solutions, and the p-CN-trityl-amidomethyl polystyrene resin was found to be the most stable of them. The above resins were applied, in parallel with Wang benzyl-type resin, well known for its stability in mild acidic conditions, to the Fmoc solid phase synthesis of the 43-amino acid residue long bioactive peptide thymosin beta-4. Independent of their differences in acid sensitivity, the resins seemed to function equally well under the conditions used, since pure thymosin beta-4 was obtained with a final yield of approximately 30% from each resin. The trityl-type amidomethyl polystyrene resins were also applied, in parallel with the Wang resin, to the Fmoc solid phase synthesis of a bioactive peptide containing proline at its C -terminus, i.e. the N -terminal tetrapeptide of thymosin beta-4, AcSDKP. In this case, the best yield (87%) was obtained with the o-Cl-trityl-amidomethyl polystyrene resin, which may be the resin of choice, of those studied, for the Fmoc solid phase peptide synthesis. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis and use of a pseudo-cysteine for native chemical ligationJOURNAL OF PEPTIDE SCIENCE, Issue 4 2003David A. Alves Abstract The process of native chemical ligation (NCL) is well described in the literature. An N -terminal cysteine-containing peptide reacts with a C -terminal thioester-containing peptide to yield a native amide bond after transesterification and acyl transfer. An N -terminal cysteine is required as both the N -terminal amino function and the sidechain thiol participate in the ligation reaction. In certain circumstances it is desirable, or even imperative, that the N -terminal region of a peptidic reaction partner remain unmodified, for instance for the retention of biological activity after ligation. This work discusses the synthesis of a pseudo- N -terminal cysteine building block for incorporation into peptides using standard methods of solid phase synthesis. Upon deprotection, this building block affords a de factoN -terminal cysteine positioned on an amino acid sidechain, which is capable of undergoing native chemical ligation with a thioester. The syntheses of several peptides and structures containing this motif are detailed, their reactions discussed, and further applications of this technology proposed. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source] Synthesis of oligopeptides with the sequence SXWS and their chemotactic effects on a ciliated protozoan Tetrahymena pyriformis,JOURNAL OF PEPTIDE SCIENCE, Issue 1 2002Eszter Illyés Abstract In this paper, the solid phase synthesis and chemical characterization of members of an SXWS sub-library (SAWS, SDWS and SKWS) as well as the comparison of their chemotactic properties with those of SEWS, which exhibits a prominent effect at 10,12M on a ciliated protozoan, Tetrahymena pyriformis, are described. We found that the chemotaxis of cells induced with the SXWS peptides varied according to the nature of the amino acid residue (Ala, Asp, Lys) in position X. The chemotactic activity of SEWS was not surpassed by any of three new tetrapeptides, although SAWS was also chemoattractant. Interestingly, SDWS, with an acidic side chain at position X, could not elicit any chemotactic response. SKWS, however, showed mild but significant chemorepellent activity over a wide concentration range. Chemotactic selection studies showed that the two chemoattractant peptides (SAWS and SEWS) had an expressed ability to select high-responder offspring cell populations. Peptides with neutral (SDWS) or chemorepellent (SKWS) properties were not able to select such subpopulations from the mixed cultures of Tetrahymena, indicating that the chemotactic response elicited by SXWS peptides is ligand-specific. For ligand-binding experiments N -terminally labelled fluorescent derivatives of SXWS peptides were prepared, applying [4-[7-hydroxycoumaryl]]acetic acid (Hca -OH) or 4-ethoxymethylene-2-[1]-naphthyl-5(4H)-oxazolone (naOx -OEt) as markers. Hca -OH was introduced using an active ester technique as the last step of SPPS, or after cleavage in solution. The oxazolone naOx -OEt reacted with the amino group of the peptide by liberation of EtOH. The binding characteristics of fixed Tetrahymena cells with the naOx -labelled peptides showed good correlation between binding profiles and chemotactic responsiveness (SEWS > SAWS > SDWS , SKWS). A similar binding pattern was observed in the case of Hca -peptides (SEWS > SAWS > SDWS). Hca -SKWS, however, bound remarkably to the cell surface. The binding activity of the Hca -peptides was less pronounced than that of the naOx -peptides, indicating the importance of the fluorophores applied. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd. [source] Microreactor Array Assembly, Designed for Diversity Oriented Synthesis Using a Multiple Core Structure Library on Solid SupportMOLECULAR INFORMATICS, Issue 11 2006Alexander Groß Abstract The application of spatially encoded principles in solid phase combinatorial synthesis requires no chemical or physical coding strategies. The resulting products are encoded by their position inside the array and their synthesis history. The advantages of microreactor arrays for solid phase synthesis as one of the embodiments in the field of microreaction technology are discussed. Here, we review the reactor design, necessary process steps, and a strategy for the diversity oriented array synthesis. In particular, the glass-made microreactor and its assembly for 1563 parallel solid phase reactions, which can be performed at temperatures up to 120,°C, are described. Bead loading and liquid handling steps were adapted to this array. The production of large libraries demands suitable synthesis protocols and building blocks. The optimization of appropriate synthesis conditions is a time-consuming process. A multiple core structure library approach for the efficient synthesis of diverse heterocyclic libraries is described. The aim of this work was to prove the feasibility of the glass-microreaction array for massive parallel library synthesis. [source] Design of (Gd-DO3A)n -polydiamidopropanoyl-peptide nucleic acid- D(Cys-Ser-Lys-Cys) magnetic resonance contrast agentsBIOPOLYMERS, Issue 12 2008Nariman V. Amirkhanov Abstract We hypothesized that chelating Gd(III) to 1,4,7-tris(carboxymethylaza)cyclododecane-10-azaacetylamide (DO3A) on peptide nucleic acid (PNA) hybridization probes would provide a magnetic resonance genetic imaging agent capable of hybridization to a specific mRNA. Because of the low sensitivity of Gd(III) as an magnetic resonance imaging (MRI) contrast agent, a single Gd-DO3A complex per PNA hybridization agent could not provide enough contrast for detection of cancer gene mRNAs, even at thousands of mRNA copies per cell. To increase the Gd(III) shift intensity of MRI genetic imaging agents, we extended a novel DO3An -polydiamidopropanoyl (PDAPm) dendrimer, up to n = 16, from the N-terminus of KRAS PNA hybridization agents by solid phase synthesis. A C-terminal D(Cys-Ser-Lys-Cys) cyclized peptide analog of insulin-like growth factor 1 (IGF1) was included to enable receptor-mediated cellular uptake. Molecular dynamic simulation of the (Gd-DO3A-AEEA)16 -PDAP4 -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) genetic imaging nanoparticles in explicit water yielded a pair correlation function similar to that of PAMAM dendrimers, and a predicted structure in which the PDAP dendron did not sequester the PNA. Thermal melting measurements indicated that the size of the PDAP dendron included in the (DO3A-AEEA)n -PDAPm -AEEA2 - KRAS PNA-AEEA- D(Cys-Ser-Lys-Cys) probes (up to 16 Gd(III) cations per PNA) did not depress the melting temperatures (Tm) of the complementary PNA/RNA hybrid duplexes. The Gd(III) dendrimer PNA genetic imaging agents in phantom solutions displayed significantly greater T1 relaxivity per probe (r1 = 30.64 ± 2.68 mM,1 s,1 for n = 2, r1 = 153.84 ± 11.28 mM,1 s,1 for n = 8) than Gd-DTPA (r1 = 10.35 ± 0.37 mM,1 s,1), but less than that of (Gd-DO3A)32 -PAMAM dendrimer (r1 = 771.84 ± 20.48 mM,1 s,1) (P < 0.05). Higher generations of PDAP dendrimers with 32 or more Gd-DO3A residues attached to PNA- D(Cys-Ser-Lys-Cys) genetic imaging agents might provide greater contrast for more sensitive detection. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1061,1076, 2008. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] | ||||||||||