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PubMed Journals Articles About "Chiral Technologies, Inc" RSS

02:13 EST 15th November 2018 | BioPortfolio

Chiral Technologies, Inc PubMed articles on BioPortfolio. Our PubMed references draw on over 21 million records from the medical literature. Here you can see the latest Chiral Technologies, Inc articles that have been published worldwide.

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Showing "Chiral Technologies" PubMed Articles 1–25 of 2,400+

Chiral pharmaceuticals: Environment sources, potential human health impacts, remediation technologies and future perspective.

Chiral pharmaceuticals (CPs), including non-steroid anti-inflammatory drugs (NSAIDs), β-blockers and some herbicide and pesticides, are widely used in aquaculture, clinical treatment and many other fields. However, people are increasingly concerned about such ubiquitous pollutants, which can frequently be detected in contaminated soil and water. In large part, the significant sources of chiral pharmaceuticals stem from industrial processes, such as the direct discharge of untreated or incompletely treated ...


Synthesis of Chiral Cyclic Alcohols from Chiral Epoxides by H or N Substitution with Frontside Displacement.

Diverse examples are provided of enantioselective sequences for the transformation of cycloalkenes to either chiral trans-β-substituted cycloalkanols or chiral α-amino ketones.

Planar-Chiral Ferrocene-based NHC Ligands.

In the last few decades, N-heterocyclic carbene (NHC) ligands characterized by attractive features have increased their presence in transition metal catalysis. However, chiral NHC ligands still require further design enhancement to realize far more exciting synthetic applications. This review documents advances in chiral NHC ligands, focusing on planar-chiral ferrocene-based NHCs. As the basic shape of most classes of NHC rings is planar, it seems rational to employ a planar-chiral element in the design of ...


The development of biphasic chiral recognition in chiral separation.

In chiral separation, enantioseparation factor is an important parameter which influences the resolution of enantiomers. In this current overview, a biphasic chiral recognition method is introduced to the readers. This method can significantly improve the enantioseparation factor in two-phase solvent through adding lipophilic and hydrophilic chiral selectors which have opposite chiral recognition ability to organic and aqueous phases, respectively. This overview presents the development and applications of ...

Liquid chromatographic enantiomer separations applying chiral ion-exchangers based on Cinchona alkaloids.

As the understanding of the various biological actions of compounds with different stereochemistry has grown, the necessity to develop methods for the analytical qualification and quantification of chiral products has become particularly important. The last quarter of the century has seen a vast growth of diverse chiral technologies, including stereocontrolled synthesis and enantioselective separation and analysis concepts. By the introduction of covalently bonded silica-based chiral stationary phases (CSPs...

A Continuously Regenerable Chiral Ammonia Borane for Asymmetric Transfer Hydrogenations.

A novel chiral ammonia borane was designed and developed via the dehydrogenation of ammonia borane with chiral phosphoric acid, which was highly effective for the asymmetric transfer hydrogenation of imines and β-enamino esters to afford high levels of reactivities and enantioselectivies. Significantly, this chiral ammonia borane can be continuously regenerated during the transfer hydrogenation with the assistance of water and ammonia borane, which allowed as low as 0.1 mol % of chiral phosphoric acid to g...

Hierarchical Emergence and Dynamic Control of Chirality in a Photoresponsive Dinuclear Complex.

Chiroptical photoswitches are of interest from a viewpoint of applications in advanced information technologies. Herein, we report dynamic on-off photoswitching of circularly polarized luminescence (CPL) in a binuclear europium complex system. Two coordination units are arranged closely in a chiral fashion by a photoresponsive ligand with a one-handed helical structure. The chirality in the helical scaffold is hierarchically transferred to the chirality in nine-coordinate complex sites. The chiral close-arr...

Stereoselective bioaccumulation and elimination of chiral PCBs 95 and 149 in earthworm Eisenia fetida.

The chiral signatures and environmental behaviors of chiral polychlorinated biphenyls (PCBs) have been extensively studied. However, information regarding chiral PCBs in invertebrates, especially earthworms, is limited. This study aimed to investigate the stereoselective bioaccumulation, elimination, and biotransformation of chiral PCBs 95 and 149 in an earthworm-soil system. Preferential enrichment of (+)-atropisomers and elimination of (-)-atropisomers were observed, for both PCBs 95 and 149, during the u...

Asymmetric Robinson Annulation of 3-Indolinone-2-carboxylates with Cyclohexenone: Access to Chiral Bridged Tricyclic Hydrocarbazoles.

A chiral bifuntional thiourea catalyzed diastereo- and enantioselective Michael addition followed by an intramolecular Aldol reaction of 3-indolinone-2-carboxylates with cyclohexenone has been accomplished using a chiral thiourea catalyst. It is a novel strategy for the construction of chiral bridged tricyclic hydrocarbazole derivatives bearing four contiguous stereocenters with excellent diastereo- and enantioselectivity.

Three-Dimensional Enantiomeric Recognition of Optically Trapped Single Chiral Nanoparticles.

We optically trap freestanding single metallic chiral nanoparticles using a standing-wave optical tweezer. We also incorporate within the trap a polarimetric setup that allows us to perform in situ chiral recognition of single enantiomers. This is done by measuring the S_{3} component of the Stokes vector of a light beam scattered off the trapped nanoparticle in the forward direction. This unique combination of optical trapping and chiral recognition, all implemented within a single setup, opens new perspe...

Chiral bambusurils for enantioselective recognition of carboxylate anion guests.

Synthesis of the first enantiomerically pure chiral bambusurils is reported. The bambusurils were prepared on the gram scale without using any chromatography techniques. The bambusurils formed supramolecular complexes with all tested chiral carboxylates including amino acids and drug molecules with the enantioselectivity ranging from 1.1 to 3.2.

Asymmetric Synthesis of Axially Chiral Benzocarbazole Derivatives Based on Catalytic Enantioselective Hydroarylation of Alkynes.

A new synthetic approach to novel axially chiral benzocarbazole derivatives based on the highly enantioselective intramolecular hydroarylation (94-96% ee) of linked alkyne-indole systems by using the prevalent chiral base catalyst, cinchonidine or cinchonine, under unprecedented transition-metal-free conditions is described. The process is considered to involve chiral base catalysis for enantioselective transformation of the alkyne part to a reaction intermediate with an axially chiral vinylidene o-quinone ...

Chiral metamaterials via Moiré stacking.

Chiral metamaterials have attracted strong interest due to their versatile capabilities in spin-dependent light manipulation. Benefiting from advancements in nanofabrication and mechanistic understanding of chiroptical effects, chiral metamaterials have shown potential in a variety of applications including circular polarizers, chiral sensors, and chiroptical detectors. Recently, chiral metamaterials made by moiré stacking, superimposing two or more periodic patterns with different lattice constants or rel...

Chiral aldehyde catalysis for the catalytic asymmetric activation of glycine esters.

Chiral aldehyde catalysis is uniquely suitable for the direct asymmetric α-functionalization of N-unprotected amino acids, because aldehydes can reversibly form imines. However, there have been few successful reports of these transformations. In fact, only chiral aldehyde catalyzed aldol reactions of amino acids and alkylation of 2-amino malonates have been reported with good chiral induction. Here, we report a novel type of chiral aldehyde catalyst based on face control of the enolate intermediates. The r...

Synthesis and Characterization of Self-Assembled Chiral FeII2L3 Cages.

We present here the synthesis of chiral BINOL derived bisamine and bispyridine-aldehyde building blocks that can be used for the self-assembly of novel chiral FeII2L3 cages when mixed with an Fe(II) precursor. The properties of a series of chiral cages were studied by NMR, CSI-MS and CD spectroscopy and molecular modelling. Upon formation of the M2L3 cages the iron corners can adopt various isomeric forms: mer, fac-Δ or fac-Λ. We found that the coordination geometry around the metal centers in R-Cage 1 an...

Enantioselective Synthesis of Tetrahydroquinolines from 2-Aminochalcones via a Consecutive One-pot Reaction Catalyzed by Chiral Phosphoric Acid.

A new asymmetric protocol for the synthesis of chiral tetrahydroquinolines from 2-aminochalcones via a two-step one-pot consecutive process (cyclization/asymmetric reduction) has been developed using chiral phosphoric acid as the sole catalyst. 2-Aminochalcones were converted into the corresponding quinolines through chiral phosphoric acid-catalyzed dehydrative cyclization, and the resultant quinolines were subsequently reduced to the chiral tetrahydroquinolines via chiral phosphoric acid-cataylzed asymmetr...

Chiral separation and modeling of quinolones on teicoplanin macrocyclic glycopeptide antibiotics CSP.

New chiral high-performance liquid chromatography (HPLC) method for the enantiomeric resolution of quinolones is developed and described. The column used was Chirobiotic T (150 × 4.6 mm, 5.0 μm). Three mobile phases used were MeOH:ACN:Water:TEA (70:10:20:0.1%), (60:30:10:0.1%), and (50:30:20:0.1%). The flow rate of the mobile phases was 1.0 mL/min with UV detection at different wavelengths. The values of retention, resolution, and separation factors ranged from 1.5 to 6.0, 1.80 to 2.25, and 2.86 to 6...

Synthesis of Chiral Tryptamines via a Regioselective Indole Alkylation.

A practical synthesis of chiral tryptamines from simple, unprotected indoles has been developed. Indole nucleophiles prepared with MeMgCl in the presence of CuCl reacted with chiral cyclic sulfamidates almost exclusively at the C-position of indole to form a variety of α- and/or β-substituted chiral tryptamines in good yield with excellent regioselectivity. The utility of this simple alkylation process has been demonstrated with the practical synthesis of two biologically active targets, cipargamin and TI...

Synthesis of enantiopure planar chiral bis-(para)-pseudo-meta-type 2.2paracyclophanes.

A new type of planar chiral (R )- and (S )-4,7,12,15-tetrasubstituted [2.2]paracyclophanes was prepared from racemic 4,7,12,15-tetrabromo[2.2]paracyclophane as the starting substrate. Regioselective lithiation and transformations afforded racemic bis-(para)-pseudo-meta-type [2.2]paracyclophane (4,15-dibromo-7,12-dihydroxy[2.2]paracyclophane). Its optical resolution was performed by the diastereomer method using a chiral camphanoyl group as the chiral auxiliary. The diastereoisomers were readily isolated by ...

Direct Synthesis of Chiral Porphyrin Macrocyclic Receptors via Regioselective Nitration.

Nitration of tetraphenylporphyrin cage compound 1, at -40 °C, leads to the regioselective formation of the chiral mononitro compound 2 (75% isolated yield) and, at -30 °C, to the achiral syn-dinitro-derivative 3 and the chiral anti-dinitro derivative 4 in a diastereomeric ratio of 5:2, which were separated by chromatography (46 and 20% yields, respectively). The structures of the compounds were confirmed by X-ray crystallography.

Proposed Spontaneous Generation of Magnetic Fields by Curved Layers of a Chiral Superconductor.

We demonstrate that two-dimensional chiral superconductors on curved surfaces spontaneously develop magnetic flux. This geometric Meissner effect provides an unequivocal signature of chiral superconductivity, which could be observed in layered materials under stress. We also employ the effect to explain some puzzling questions related to the location of zero-energy Majorana modes.

Chiral Lithium Amido Zincates for Enantioselective 1,2-Additions: Auto-assembling Reagents Involving a Fully Recyclable Ligand.

A methodology consisting in carrying out enantioselective nucleophilic 1,2-additions (ees up to 97%) from cheap, easily accessible, and never described before, chiral lithium amido zincates is presented. These multicomponent reactants auto-assemble when mixing, in a 1 : 1 ratio, a homoleptic diorganozinc (R2Zn) with a chiral lithium amide (CLA). The latter, obtained after a single reductive amination, plays the role of the chiral inductor and is fully recoverable thanks to a simple acid-base wash, allowing ...

Preparation of a chiral Pt tetrahedral cage and its use in catalytic Michael addition reaction.

The reaction of chiral cis-[(1S,2S)-dch]Pt(NO3)2 (M) [where (1S,2S)-dch = (1S,2S)-1,2-diaminocyclohexane] with a hexadentate ligand (L) in 3 : 1 stoichiometric ratio yielded a [12+4] self-assembled chiral M12L4 molecular tetrahedron (T). The cage T features an internal 3D nanocavity with large open 'windows', enabling it to catalyze Michael addition reactions of a series of nitrostyrene derivatives with indole in a 9 : 1 water : methanol mixture.

Colorimetric chiral recognition of D/L-phenylalanine based on triangular silver nanoplates.

A new colorimetric analysis approach for chiral recognition of D- and L-forms of phenylalanine (phe) was developed based on triangular silver nanoplates (TAg-NPs). The TAg-NPs could be used as chiral colorimetric probes for D- and L-forms of phe. Upon addition of D-phe to TAg-NPs solution, a color change from blue to purple to pink could be observed, while no obvious color change was found on addition of L-phe. L-phe could prevent the TAg-NPs from being etched to small size particles while the protective ef...

Enantioselective Access to S-Chiral 1,2-Benzothiazines by CpxRh(III) Catalyzed C-H Functionalization of Sulfoximines.

Sulfoximines with stereogenic sulfur atoms are attractive structural motifs in drug discovery. A direct catalytic enantioselective method accessing S-chiral 1,2-benzothiazines from readily accessible diarylsulfoximines is presented. Rhodium(III) complexes equipped with chiral cyclopentadienyl ligands and paired with suitable carboxylic acid additives engage in an enantiodetermining C-H activation directed by the sulfoximine group. Subsequent trapping of the rhodacycle by a broad range of diazoketones gives ...


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