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PubMed Journal Database | ACS combinatorial science RSS

02:25 EDT 21st May 2013 | BioPortfolio

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Showing PubMed Articles 1–25 of 114 from ACS combinatorial science

425815

Development of four-component synthesis of tetra- and pentasubstituted polyfunctional dihydropyrroles: free permutation and combination of aromatic and aliphatic amines.

We previously reported the novel efficient proton/heat-promoted four-component reactions (4CRs) of but-2-ynedioates, two same/different primary amines, and aldehydes for the synthesis of tetra- and pentasubstituted polyfunctional dihydropyrroles. If aromatic and aliphatic amines were used as reagents, four different series of products should be obtained via the permutation and combination of aromatic and aliphatic primary amines. However, only three/two rather four different series of tetra-/pentasubstisute...

425811

Microwave-Mediated Reduction of Disulfide Bridges with Supported (Tris(2-carboxyethyl)phosphine) as Resin-Bound Reducing Agent.

We report on the synthesis and use of a new supported reagent consisting in tris(2-carboxyethyl)phosphine (TCEP) immobilized on hydrophilic PEG based resin beads. Used in conjunction with a 5 min microwave (MW) irradiation, "supported TCEP" reduced disulfide bridges in free thiols in peptides having two or more cysteine residues. Separation of reaction products from reducing agent was easily performed by simple filtration.

425806

One-Pot Syntheses of Isoquinolin-3-ones and Benzo-1,4-diazepin-2,5-diones Utilizing Ugi-4CR Post-Transformation Strategy.

One-pot and efficient syntheses of structurally diverse isoquinolin-3-ones and isoquinolin-3-one-based benzo-1,4-diazepin-2,5-diones have been developed. The notable features of the process include the Ugi condensation of monomasked phthalaldehydes with amines, carboxylic acids, and isonitriles, followed by HClO4-mediated intramolecular condensation of the carbonyl with amide.

425798

Column Chromatography-Free Solution-Phase Synthesis of a Natural Piper-Amide-like Compound Library.

We have achieved an efficient solution-phase parallel synthesis of a library of natural piper-amide-like compounds from the bifunctional β-phosphono-N-hydroxy-succinimidyl ester intermediate. The primary important feature in our study is the construction of natural-product-like molecules through the adaptation of sophisticated organic reactions that create water-soluble byproducts for a chromatography-free purification. This simple and efficient method rapidly provides a combinatorial library of high yield...

425790

Solution-phase synthesis of a diverse library of benzisoxazoles utilizing the 3 + 2 cycloaddition of in situ-generated nitrile oxides and arynes.

A library of benzisoxazoles has been synthesized by the [3 + 2] cycloaddition of nitrile oxides with arynes and further diversified by acylation/sulfonylation and palladium-catalyzed coupling processes. The eight key intermediate benzisoxazoles have been prepared by the reaction of o-(trimethylsilyl)aryl triflates and chlorooximes in the presence of CsF in good to excellent yields under mild reaction conditions. These building blocks have been used as the key components of a diverse set of 3,5,6-trisubstitu...

425783

Toward the Combinatorial Selection of Chemically Modified DNAzyme RNase A Mimics Active Against all-RNA Substrates.

The convenient use of SELEX and related combinatorial methods of in vitro selection provides a formidable gateway for the generation of DNA enzymes, especially in the context of improving their potential as gene therapeutic agents. Here, we report on the selection of DNAzyme 12-91, a modified nucleic acid catalyst adorned with imidazole, ammonium, and guanidinium groups that provide for efficient M(2+)-independent cleavage of an all-RNA target sequence (kobs = 0.06 min(-1)). While Dz12-91 was selected for i...

400255

Selection of Chiral Zinc Catalysts for the Kinetic Resolution of Esters via Dynamic Templating.

Dynamic combinatorial libraries of chiral tetradentate bis-imine zinc(II) complexes have been prepared and screened for (1) their discrimination of enantiomeric picolinate esters and pyridyl phosphonate transition state analogs (TSAs) and (2) their catalytic activity and selectivity for enantioselective methanolysis of racemic picolinate esters. The zinc complexes are in equilibrium with their imine ligands as well as with the aldehyde and amine building blocks that form them, enabling the composition of th...

400248

Global analysis of Peptide cyclization efficiency.

Cyclic peptides are of considerable interest in drug discovery and nanotechnology. However, macrocyclization of peptides and other compounds has often been perceived as synthetically challenging and the cyclization yields are affected by several factors including the ring size, peptide sequence, and the reaction conditions. Through the screening of combinatorial peptide libraries, we analyzed the cyclization efficiency of >2 million peptide sequences to determine the effect of ring size, peptide sequence, a...

400242

Evaluation of the SO(2) and NH(3) Gas Adsorption Properties of CuO/ZnO/Mn(3)O(4) and CuO/ZnO/NiO Ternary Impregnated Activated Carbon Using Combinatorial Materials Science Methods.

Impregnated activated carbons (IAC) are widely used materials for the removal of toxic gases in personal respiratory protection applications. The combinatorial method has been employed to prepare IACs containing different types of metal oxides in various proportions and evaluate their adsorption performance for low molecular weight gases, such as SO(2) and NH(3), under dry conditions. Among the metal oxides used for the study, Mn(3)O(4) was found to have the highest capacity for retaining SO(2) gas under dr...

400235

Combinatorial search for improved metal oxide oxygen evolution electrocatalysts in acidic electrolytes.

A library of electrocatalysts for water electrolysis under acidic conditions was created by ink jet printing metal oxide precursors followed by pyrolysis in air to produce mixed metal oxides. The compositions were then screened in acidic electrolytes using a pH sensitive fluorescence indicator that became fluorescent due to the pH change at the electrode surface because of the release of protons from water oxidation. The most promising materials were further characterized by measuring polarization curves an...

400234

Experimental Screening of Porous Materials for High Pressure Gas Adsorption and Evaluation in Gas Separations: Application to MOFs (MIL-100 and CAU-10).

A high-throughput gas adsorption apparatus is presented for the evaluation of adsorbents of interest in gas storage and separation applications. This instrument is capable of measuring complete adsorption isotherms up to 40 bar on six samples in parallel using as little as 60 mg of material. Multiple adsorption cycles can be carried out and four gases can be used sequentially, giving as many as 24 adsorption isotherms in 24 h. The apparatus has been used to investigate the effect of metal center (MIL-100) a...

400226

Streamlined protocol for mRNA display.

mRNA display is a powerful method for in vitro directed evolution of polypeptides, but its time-consuming, technically demanding nature has hindered its widespread use. We present a streamlined protocol in which lengthy mRNA purification steps are replaced with faster precipitation and ultrafiltration alternatives; additionally, other purification steps are entirely eliminated by using a reconstituted translation system and by performing reverse transcription after selection, which also protects input polyp...

400218

One Pot Regioselective Synthesis of a Small Library of Dibenzob,f1,4thiazepin-11(10H)-ones via Smiles Rearrangement.

A facile and efficient method has been developed for the synthesis of a small library of dibenzo[b,f][1,4]thiazepin-11(10H)-ones via Smiles rearrangement. Compounds were obtained in excellent isolated yields (70%-92%) under metal-free conditions. More specifically, this transition metal-free process relates to an environmentally friendly, economical, and efficient method for preparing benzoic-fused seven-membered lactams.

400213

Three-Component Domino Reactions for Regioselective Formation of Bis-indole Derivatives.

A microwave-assisted regioselective reaction dealing with arylglyoxal monohydrate, diverse N-aryl enaminones, and indoles to achieve 3,2'- and 3,3'-bis-indoles by varying a substituted indole substrate is reported. The 2-unsubstituted indoles resulted in the 3,2'-bis-indole skeleton, whereas indoles bearing a methyl or phenyl group at C2 led to the 3,3'-bis-indoles with simultaneous formation of three sigma-bonds. The procedures feature excellent regioselectivity, short reaction times, convenient one-pot ma...

377442

Application of a Simultaneous TGA-DSC Thermal Analysis System for High-Throughput Screening of Catalytic Activity.

We present here the use of a simultaneous TGA/DSC thermal analyzer as a high-throughput reactor system to measure after calibration the heat of reaction and therefore the catalytic activity of heterogeneous catalysts in a fast, reliable and reproducible manner. By coupling the gas outlet of the analyzer with a mass spectrometer via a heated capillary additional data can be acquired. As a test reaction the oxidation of carbon monoxide with synthetic air, using Hopcalite and several transition and noble metal...

375000

Optimization of the single-phased white phosphor of Li2SrSiO4: Eu2+, Ce3+ for light-emitting diodes by using the combinatorial approach assisted with the Taguchi method.

The best performance of the phosphor Li2SrSiO4: Eu2+, Ce3+ in terms of luminescence efficiency (LE), color rendering index (CRI) and color temperature (Tc) for light-emitting diode application was optimized with combinatorial approach. The combinatorial libraries were synthesized with solution-based method and the scale-up samples were synthesized with conventional solid-reaction method. Crystal structure was investigated by using the X-ray diffraction spectrometer. The emission spectra of each sample in co...

357176

Micro-gradient-heaters as tools for high-throughput experimentation.

A micro-gradient-heater (MGH) was developed and its feasibility as a tool for high-throughput materials science experimentation was tested. The MGH is derived from micro-hotplate (MHP) systems and allows combinatorial thermal processing on the micro-nano scale. The temperature gradient is adjustable by the substrate material. For an Au-coated MGH membrane a temperature drop from 605°C to 100°C was measured over a distance of 965 µm, resulting in an average temperature change of 0.52 K/µm. As a proof of...

336308

Automated Parallel Freeze-Evacuate-Thaw Degassing Method for Oxygen-Sensitive Reactions: RAFT Polymerization.

An automated and parallel freeze-evacuate-thaw degassing method in a commercially available synthesizer is disclosed and tested for its applicability to reversible addition-fragmentation chain transfer (RAFT) polymerization. The effectiveness of this method to eliminate oxygen in polymerization reactions is demonstrated by directly comparing it against experiments performed using conventional laboratory techniques. Apart from the demonstrated accuracy, the proposed method has also shown significant precisio...

335711

Piperazine Amide Linker for Cyclative Cleavage from Solid Support: Traceless Synthesis of Dihydroquinoxalin-2-ones.

A piperazine amide linker for cyclative cleavage from solid support and its use in the traceless solid-phase synthesis of dihydroquinoxalinones are described. Piperazine was attached to Wang resin via a carbamate linkage and acylated with Fmoc-amino acids. Following Fmoc group removal, resin-bound amines were reacted with 1-fluoro-2-nitrobenzenes. The nitro group of the resulting 2-nitroanilines was reduced, and acyclic precursors, in contrast to traditional ester-type linkage, remained attached to the resi...

332579

Combinatorial Solid-Phase Synthesis of 4,6-Diaryl and 4-Aryl, 6-alkyl-1,3,5-triazines and their Application to Efficient Biofuel Production.

Herein we report the solid-phase synthesis of a combinatorial aryl, alkyl-triazine library and its applica-tion to biofuel production. The combination of Grignard reactions and solid supported Suzuki coupling reactions afforded unique 120 triazine compounds with high purities and minimum purification steps. Through an unbiased phenotypic screening for improved biofuel generation in oleaginous yeast, we found one diaryl triazine derivative (E4) which increased the biolipid production up to 86%.

331895

Combinatorial Bulk Ceramic Magnetoelectric Composite Libraries of Strontium Hexaferrite and Barium Titanate.

Bulk ceramic combinatorial libraries were produced via a novel, high-throughput (HT) process, in the form of polycrystalline strips with a gradient composition along the length of the library. Step gradient ceramic composite libraries with 10 mol % steps of SrFe(12)O(19)-BaTiO(3) (SrM-BT) were made and characterized using HT methods, as a proof of principle of the combinatorial bulk ceramic process, and sintered via HT thermal processing. It was found that the SrM-BT libraries sintered at 1175 °C had the o...

331891

Spatially Resolved Solid-State 1H NMR for Evaluation of Gradient-Composition Polymeric Libraries.

Polyurethane libraries consisting of films with composition gradients of aliphatic polyisocyanate and hydroxy-terminated polyacrylate resin was characterized using methods of 1H NMR micro-imaging (i.e., MRI) and solid-state NMR. Molecular mobilities and underlying structural information were extracted as a function of the relative content of each of the two components. Routine NMR micro-imaging using the spin-echo sequence only allows investigations of transverse relaxation of magnetization at echo times >...

321173

Development and Evaluation of a Solid Supported Cyclobutadieneiron Tricarbonyl Complex for Parallel Synthesis Applications.

Cycloadditions of cyclobutadiene can offer rapid access to rigid polycyclic ring systems. Further functionalization of these strained-ring cycloadducts can lead to unique scaffolds for probing unexplored regions of chemical space. Along these lines, opportunities for high throughput syntheses of these novel systems could be facilitated with the introduction of an immobilized cyclobutadiene reagent. Reported herein are preliminary studies of an iron tricarbonyl cyclobutadiene complex attached to solid suppor...

316872

Mineralization of gaseous acetaldehyde by electrochemically generated Co(III) in H2SO4 with wet scrubber combinatorial system.

Electrochemically generated Co(III) mediated catalytic room temperature incineration of acetaldehyde, which is one of volatile organic compounds (VOCs), combined with wet scrubbing system was developed and investigated. Depending on the electrolyte's type, absorption come removal efficiency is varied. In presence of electrogenerated Co(III) in sulfuric acid, acetaldehyde was mineralized to CO2 not like only absorption in pure sulfuric acid. The Co(III) mediated catalytic incineration led to oxidative absorp...

299608

Synthesis of a γ-Lactam Library via Formal Cycloaddition of Imines and Substituted Succinic Anhydrides.

Formal cycloaddition reactions between imines and cyclic anhydrides serve as starting point for the synthesis of diverse libraries of small molecules. The synthesis of succinic anhydrides substituted with electron-withdrawing groups is facilitated by new mild conditions for alkylation of aryl-substituted acetyl esters with ethyl bromoacetate. These anhydrides are then used in formal cycloaddition reactions with imines to produce γ-lactams. 2-Fluoro-5-nitrophenylsuccinic anhydride reacts efficiently with im...


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