Synthesis, resolution, and chiroptical properties of hemicryptophane cage controlling the chirality of propeller arrangement of a C3 triamide unit.
nez A Abstract The five-steps synthesis of a hemicryptophane cage combining a benzene-1,3,5-tricarboxamide unit and a cyclotriveratrylene (CTV) moiety is described. Chiral high-performance liquid chromatography (HPLC) was used to resolve the racemic mixture. The absolute configuration of the isolated enantiomers was assigned by comparison of the experimental electronic circular dichroism (ECD) spectra with the calculated ones. X-ray molecular structures reveal that the capped benzene-1,3,5-tricarboxamide unit adopts a structurally chiral conformation in solid state: the chirality of CTV moiety controls the &Lambda...
Source: Chirality - September 2, 2019 Category: Molecular Biology Authors: Long A, Jean M, Albalat M, Vanthuyne N, Giorgi M, Górecki M, Dutasta JP, Martinez A Tags: Chirality Source Type: research

Helicity of perfluoroalkyl chains controlled by the self-assembly of the Ala-Ala dipeptides.
Abstract Four Ala-Ala dipeptides with a perfluoroalkyl chain at the N-terminal were synthesized. They were able to self-assemble into helical nanofibers and/or twisted nanobelts in a mixture of DMSO/H2 O. The handedness of nanofibers and nanobelts was controlled by the chirality of the alanine at the N-terminal. The stacking handedness of the phenylene groups and the helicity of the perfluoroalkyl chain were studied using circular dichroism spectroscopy and vibrational circular dichroism, respectively. The chirality of the alanine at N-terminal controlled the stacking handedness of the neighboring phenylene groups...
Source: Chirality - August 29, 2019 Category: Molecular Biology Authors: Zhang L, Lin S, Tong Q, Li Y, Wang Y, Li Y, Li B, Yang Y Tags: Chirality Source Type: research

Whole-cell biocatalytic of Bacillus cereus WZZ006 strain to synthesis of indoxacarb intermediate: (S)-5-Chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indene-2-carboxylic acid methyl ester.
This study demonstrates a new biocatalytic process route for preparing the indoxacarb chiral intermediates and provides a theoretical basis for the application of new insecticides in agricultural production. PMID: 31468608 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - August 29, 2019 Category: Molecular Biology Authors: Zhang Y, Zhang H, Cheng F, Xia Y, Zheng J, Wang Z Tags: Chirality Source Type: research

Improved chiral electrochemical recognition of tryptophan enantiomers based on three-dimensional molecularly imprinted overoxidized polypyrrole/MnO2 /carbon felt composites.
Abstract A three-dimensional molecularly imprinted overoxidized polypyrrole/MnO2 /carbon felt (MIOPPy/MnO2 /CF) composites were fabricated, which results in increased active area of the surface of the molecularly imprinted polymers film and greatly improved electrochemical chiral recognition effect for tryptophan isomers. The composites were characterized by field emission scanning electron microscope, transmission electron microscope, X-ray diffractometer, UV-visible spectra, N2 adsorption-desorption isotherms, and electrochemical methods. The manuscript provides a proof of concept and shows promising potential o...
Source: Chirality - August 28, 2019 Category: Molecular Biology Authors: Dong L, Liu X, Xu H, Wu D, Gao S, Zhong L, Kong Y Tags: Chirality Source Type: research

Axially chiral N,N'-dioxides ethers for catalysis in enantioselective allylation of aldehydes.
Abstract A series of axially chiral ethers synthesized from biscarboline N,N'-dioxides, (S)-1a to (S)-1n, was investigated in enantioselectivity addition reactions of allyltrichlorosilane with a series of substituted aldehydes, including bulky substituted aldehydes. High enantioselectivities (up to 96%ee) were achieved using the catalyst (S)-1k at 1 mol % loading. PMID: 31456306 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - August 28, 2019 Category: Molecular Biology Authors: Wu S, Xing Y, Wang J, Guo X, Zhu H, Li W Tags: Chirality Source Type: research

Conformational, configurational, and supramolecular studies of podocephalol acetate from Lasianthaea aurea.
;a-Rojas CM, Joseph-Nathan P, Del Río RE Abstract Although podocephalol (1) and its derived acetate 2 were found in Lasianthaea podocephala four decades ago, and 1 was later detected in the essential oils of several vegetal species, its absolute configuration (AC) and conformational preferences remained to be established. The structures of ar-himachalene 1, now isolated from Lasianthaea aurea, and its derived acetate 2, were herein confirmed by extensive 1D and 2D nuclear magnetic resonance (NMR) studies, while the conformational preferences of the cycloheptene was established by density functional theory (...
Source: Chirality - August 27, 2019 Category: Molecular Biology Authors: Rodríguez-García G, Villagómez-Guzmán AK, Talavera-Alemán A, Cruz-Corona R, Gómez-Hurtado MA, Cerda-García-Rojas CM, Joseph-Nathan P, Del Río RE Tags: Chirality Source Type: research

Enantioseparation and determination of flumequine enantiomers in multiple food matrices with chiral liquid chromatography coupled with tandem mass spectrometry.
Abstract The present work firstly described the enantioseparation and determination of flumequine enantiomers in milk, yogurt, chicken, beef, egg, and honey samples by chiral liquid chromatography-tandem mass spectrometry. The enantioseparation was performed under reversed-phase conditions on a Chiralpak IC column at 20°C. The effects of chiral stationary phase, mobile phase components, and column temperature on the separation of flumequine enantiomers have been studied in detail. Target compounds were extracted from six different matrices with individual extraction procedure followed by cleanup using Cleanert...
Source: Chirality - August 22, 2019 Category: Molecular Biology Authors: Li S, Liu B, Xue M, Yu J, Guo X Tags: Chirality Source Type: research

Synthesis of alternating metallocopolymers by chiral recognition.
We report the synthesis of chiral enantiopure polytopic bridging ligands, which may lead to the formation of metallosupramolecular polymers with zinc (II) as metal linker. We show that chiral C2 -symmetric bisoxazoline ligands are useful moieties to efficiently generate heterochiral complexes and thus polymeric entities. The corresponding metallopolymers were further characterized by powder X-ray diffraction (PXRD) to obtain information on the level of crystallinity of our different metallopolymers. PMID: 31435971 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - August 22, 2019 Category: Molecular Biology Authors: Torres-Werlé M, Heinrich B, Maisse-François A, Bellemin-Laponnaz S Tags: Chirality Source Type: research

Absolute configuration of phomactatriene diterpenoids obtained by Wagner-Meerwein rearrangement of epimeric verticillols.
s CM, Joseph-Nathan P, Hernández-Hernández JD Abstract The epimeric diterpenes (+)-(1S,3E,7E,11S,12S)-verticilla-3,7-dien-12-ol (1), isolated from Bursera suntui, and (+)-(1S,3E,7E,11S,12R)-verticilla-3,7-dien-12-ol (2), isolated from Bursera kerberi, gave the same Wagner-Meerwein rearrangement product (-)-(1E,4Z,8Z,11S,12R)-phomacta-1,(15)4,8-triene (3). The Et2 O:BF3 -induced transformations evidence that verticillenes and phomactanes, both containing the bicyclo[9.3.1]pentadecane skeleton, are biogenetically related through the verticillen-12-yl cation (A+ ), which also is a key intermediate in th...
Source: Chirality - August 22, 2019 Category: Molecular Biology Authors: Del Río-Chávez ÁA, García-Gutiérrez HA, Román-Marín LU, Beiza-Granados L, Cerda-García-Rojas CM, Joseph-Nathan P, Hernández-Hernández JD Tags: Chirality Source Type: research

Improving enantiomeric resolutions by avoiding peak distortion effects in on-line coupled liquid chromatography to gas chromatography.
aiz M Abstract In this work, we study the effect of different variables affecting elution profile distortion on the enantiomeric resolution eventually achievable when working with on-line coupled liquid chromatography to gas chromatography (LC-GC). Specifically, the proposed configuration combines achiral reversed-phase liquid chromatography (RPLC) and chiral gas chromatography (enantio-GC), with heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin as enantioselective stationary phase to analyse target fractions transferred (from LC to GC) via the through oven transfer adsorption desorption (TOTAD) interface. The hig...
Source: Chirality - August 20, 2019 Category: Molecular Biology Authors: Martínez RM, Barba C, Robredo S, Herraiz M Tags: Chirality Source Type: research

Green synthesis of enantiopure (S)-1-(benzofuran-2-yl)ethanol by whole-cell biocatalyst.
In this study, a basic and novel whole-cell mediated biocatalytic method was performed for the enantiopure production of (S)-1-(benzofuran-2-yl)ethanol in the aqueous medium, which empowered the synthesis of a precious chiral intermediary process to be converted into a sophisticated molecule for drug production. PMID: 31423658 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - August 19, 2019 Category: Molecular Biology Authors: Şahin E Tags: Chirality Source Type: research

HPLC and SFC enantioseparation of ( ±)-Corey lactone diol: Impact of the amylose tris-(3,5-dimethylphenylcarbamate) coating amount on chiral preparation.
HPLC and SFC enantioseparation of (±)-Corey lactone diol: Impact of the amylose tris-(3,5-dimethylphenylcarbamate) coating amount on chiral preparation. Chirality. 2019 Aug 19;: Authors: Wang H, Wang Q, Wu Y, Cheng L, Zhu L, Zhu J, Ke Y Abstract As an important intermediate of prostaglandins and entecavir, optically pure Corey lactone diol (CLD) has great value in the pharmaceutical industry. In this work, the enantioseparation of (±)-CLD was evaluated using high-performance liquid (HPLC) and supercritical fluid chromatography (SFC). In HPLC, the separations of CLD enantiomers on polysac...
Source: Chirality - August 19, 2019 Category: Molecular Biology Authors: Wang H, Wang Q, Wu Y, Cheng L, Zhu L, Zhu J, Ke Y Tags: Chirality Source Type: research

Use of chiral auxiliaries in the asymmetric synthesis of biologically active compounds: A review.
iaz M Abstract This review article describes the use of some of the most popular chiral auxiliaries in the asymmetric synthesis of biologically active compounds. Chiral auxiliaries derived from naturally occurring compounds, such as amino acids, carbohydrates, and terpenes, are considered essential tools for the construction of highly complex molecules. We highlight the auxiliaries of Evans, Corey, Yamada, Enders, Oppolzer, and Kunz, which led to remarkable progress in asymmetric synthesis in the last decades and continue to bring advances until the present day. PMID: 31418934 [PubMed - as supplied by publish...
Source: Chirality - August 16, 2019 Category: Molecular Biology Authors: Diaz-Muñoz G, Miranda IL, Sartori SK, de Rezende DC, Alves Nogueira Diaz M Tags: Chirality Source Type: research

Enantioseparation of chiral perfluorooctane sulfonate (PFOS) by supercritical fluid chromatography (SFC): Effects of the chromatographic conditions and separation mechanism.
In this study, a method of perfluoro-1-methylheptane sulfonate (1 m-PFOS) enantioseparation by SFC was established. The optimal separation was obtained using a Chiralpak QN-AX column with CO2 /2-propanol (70/30, v/v) as the mobile phase with a flow rate of 1 mL/min, column temperature was 32°C, and BPR pressure was 1800 psi. The resolution (Rs) and retention time were 0.88 and 130 minutes, respectively. This method is more economic and greener than HPLC. Modifier pH and column temperature were determined to be significant factors of SFC chiral separation. Modifier pH is negatively correlated with th...
Source: Chirality - August 13, 2019 Category: Molecular Biology Authors: Zhao L, Chen F, Guo F, Liu W, Liu K Tags: Chirality Source Type: research

Enantiomeric separation of vilanterol trifenatate by chiral liquid chromatography.
Abstract Vilanterol trifenatate is a novel chiral long-acting β2-agonist developed. Vilanterol combined with inhaled corticosteroids can treat COPD and asthma. A simple liquid chromatographic method is developed for the quantitative determination of R-vilanterol and S-vilanterol (impurity S). HPLC separation was achieved on Chiralpak ID (250 × 4.6 mm; particle size 5 μm) column using hexane-ethanol-ethanolamine (75:25:0.1, v/v/v) as mobile phase at a flow rate of 1.0 mL/min. The resolution is greater than 3.3. Ethanolamine in the mobile phase is vital to enhance chromatograph...
Source: Chirality - August 8, 2019 Category: Molecular Biology Authors: Guo Y, Yang Y, Peng J, Zhu X, Ji Z Tags: Chirality Source Type: research

Chiral superstructures from homochiral Zn2+ , Co2+ , Fe2+ -2,6-bis (aryl ethylimine)pyridine complexes.
We report the hierarchical supramolecular organization of metallosupramolecular homochiral complexes 1-Λ-(S,S,S,S)-M2+ /1-∆-(R,R,R,R)-M2+ and 2- Λ-(S,S,S,S)-M2+ /2-∆- (R,R,R,R)-M2+ of M2+ = Co2+ , Fe2+ , Zn2+ metal ions with chiral pseudo-terpyridine-type ligands: 1-(S,S) or 1-(R,R) = 2,6-bis (naphthyl ethylimine)pyridine and 2-(S,S) or 2-(R,R) = 2,6-bis (phenyl-ethylimine)pyridine. Circular dichroism measurements in solution were used to confirm the enantiomeric nature of all twelve complexes. For crystal structures of 1- Λ- (S,S,S,S)-M2+ or 1-∆- (R,R,R,R)-M2+ complexes, absolute configurations ...
Source: Chirality - August 8, 2019 Category: Molecular Biology Authors: Dumitru F, van der Lee A, Barboiu M Tags: Chirality Source Type: research

Practical method for increasing optical purity of cis-verbenol.
Abstract R/S mixture of monoterpene alcohol cis-verbenol can be separated in preparative scale by its conversion into phthalic mono-ester and subsequent crystallization of its diastereomeric salts with (R)-α-methylbenzylamine and (S)-α-methylbenzylamine. Finally, basic methanolysis of the resolved phthalic mono-esters results (S)-cis-verbenol and (R)-cis-verbenol in high enantiomeric and diastereomeric purity. PMID: 31393641 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - August 8, 2019 Category: Molecular Biology Authors: Kovalenko V, Krauchanka A, Prokhorevich K Tags: Chirality Source Type: research

Optimization of ASE and SPE conditions for the HPLC-FLD detection of piperazine in chicken tissues and pork.
Abstract Accelerated solvent extraction (ASE) and solid-phase extraction (SPE) conditions were optimized by a high-performance liquid chromatography-fluorescence detector (HPLC-FLD) method for the detection of piperazine in chicken tissues and pork. Piperazine residues were determined by precolumn derivatization with trimethylamine and dansyl chloride. Samples were extracted with 2% formic acid in acetonitrile using an ASE apparatus and purified using a Strata-X-C SPE column. The monosubstituted product of the reaction of piperazine with dansyl chloride was 1-dansyl piperazine (1-DNS-piperazine). Chromatographic s...
Source: Chirality - August 6, 2019 Category: Molecular Biology Authors: Liu C, Xie X, Wang B, Zhao X, Guo Y, Zhang Y, Bu X, Xie K, Wang Y, Zhang T, Zhang G, Liu X, Dai G, Wang J Tags: Chirality Source Type: research

Simultaneous determination of guaifenesin enantiomers and ambroxol HCl using 50-mm chiral column for a negligible environmental impact.
Abstract Chiral stationary phases are conveniently used for enantiomeric separation of drugs by liquid chromatography. Consumption of large volumes of hazardous solvents is considered as a common challenge for the sustainability of this technique. To this end, a columnar chromatography has been adopted using 50-mm-length stationary phases. The study comprised five Phenomenex Lux cellulose- and amylose-based columns for the separation of guaifenesin (GUA) enantiomers. In addition, an experimental design was used to optimize the gradient profile for the separation of racemic GUA and ambroxol HCl (AMB) binary mixture...
Source: Chirality - August 1, 2019 Category: Molecular Biology Authors: Tantawy MA, Yehia AM, Aboul-Enein HY Tags: Chirality Source Type: research

Chirality in amino acids beyond the C α configuration.
Chirality in amino acids beyond the Cα configuration. Chirality. 2019 Jul 29;: Authors: Brunner H, Tsuno T Abstract Based on a CSD search, a meta-analysis of 1179 structures of 19 natural amino acids H3 NCα H(R)C'(O)O and their derivatives H3 NCα H(R)C'(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that the chirality chain with its two steps, established in the preceding paper for alanine, can be extended to natural amino acids. High diastereoselectivities are observed in the induction from the L configuration at Cα to the -ψ and +ψ c...
Source: Chirality - July 29, 2019 Category: Molecular Biology Authors: Brunner H, Tsuno T Tags: Chirality Source Type: research

Highly selective recognition of L-phenylalanine with molecularly imprinted polymers based on imidazolyl amino acid chiral ionic liquid.
Abstract Several amino acid chiral ionic liquids were introduced as functional monomers to prepare molecularly imprinted polymers for specific recognition of L-phenylalanine. Among them, the imprinted polymers L-Phe@MIPs based on [ViImC3][L-Pro] showed the best selective recognition ability for L-phenylalanine. A series of experiments such as dynamic adsorption, static adsorption, and competitive adsorption were conducted to investigate the specific recognition ability and adsorption capacity of the L-Phe@MIPs. It is found that the adsorption efficiency to L-phenylalanine on L-Phe@MIPs was 3.11 times higher than t...
Source: Chirality - July 25, 2019 Category: Molecular Biology Authors: Chen S, Huang X, Yao S, Huang W, Xin Y, Zhu M, Song H Tags: Chirality Source Type: research

On the role played by the chirality of ligands on the aggregation of heterometallic CuII -HgII complexes.
Abstract Copper(II) complexes constructed from enantiopure Schiff-base ligands derived from o-vanillin and methionine or from their racemic mixture have been employed as metalloligands towards mercury(II) ions. The nature of the heterometallic CuII -HgII complexes (coordination polymers or oligonucler species), resulted from the reactions of the copper(II) complexes with HgCl2 or HgI2 , is different. The enantiopure metalloligands lead to chiral coordination polymers, 1 ∞ [{Cu(R-/S-valmet)(H2 O)}2 HgCl2 ]·5H2 O·CH3 OH and 2 ∞ [{Cu2 (R-/S-valmet)2 (μ-H2 O)(H2 O)2 }HgI2 ]·4H2 O. T...
Source: Chirality - July 24, 2019 Category: Molecular Biology Authors: Maxim C, Muntean D, Andruh M Tags: Chirality Source Type: research

Selective distortion of the planar group C α C'(O)O to a chiral flat tetrahedron in the amino acid alanine.
Selective distortion of the planar group Cα C'(O)O to a chiral flat tetrahedron in the amino acid alanine. Chirality. 2019 Jul 23;: Authors: Brunner H, Tsuno T Abstract Based on a Cambridge Structural Database (CSD) search, a meta-analysis of 116 structures of alanine H3 NCα H(CH3 )C'(O)O and its derivatives H3 NCα H(CH3 )C'(O)O(H/R/M), protonated, esterified, or coordinated at the carboxylic group, shows that in the first step of a chirality chain, the L configuration at Cα induces (M) and (P) conformations with respect to rotation around the central C'─Cα bond. In the...
Source: Chirality - July 23, 2019 Category: Molecular Biology Authors: Brunner H, Tsuno T Tags: Chirality Source Type: research

Enantioselective liquid-liquid extraction of 3-chloro-phenylglycine enantiomers using (S,S)-DIOP as extractant.
Abstract (S,S)-DIOP, a common catalyst used in asymmetric reaction, was adopted as chiral extractant to separate 3-chloro-phenylglycine enantiomers in liquid-liquid extraction. The factors affecting extraction efficiency were studied, including metal precursors, organic solvents, extraction temperature, chiral extractant concentration, and pH of aqueous phase. (S,S)-DIOP-Pd exhibited good ability to recognize 3-chloro-phenylglycine enantiomers, and the operational enantioselectivity (α) is 1.836. The highest performance factor (pf) was obtained under the condition of extraction temperature of 9.1°C, (S,S...
Source: Chirality - July 22, 2019 Category: Molecular Biology Authors: Liu X, Ma Y, Xu L, Liu Q Tags: Chirality Source Type: research

Enantiomeric impurities in chiral catalysts, auxiliaries, and synthons used in enantioselective syntheses. Part 5.
This report presents chiral liquid chromatography (LC) and gas chromatography (GC) methods to separate enantiomers of chiral compounds and evaluate their enantiomeric purities. The accurate and efficient LC analysis was done using newly introduced superficially porous particle (SPP 2.7 μm) based chiral stationary phases (TeicoShell, VancoShell, LarihcShell-P, and NicoShell). PMID: 31318099 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - July 18, 2019 Category: Molecular Biology Authors: Thakur N, Patil RA, Talebi M, Readel ER, Armstrong DW Tags: Chirality Source Type: research

Enantiopure 4-oxazolin-2-ones and 4-methylene-2-oxazolidinones as chiral building blocks in a divergent asymmetric synthesis of heterocycles.
elgado F, Jiménez-Vázquez HA, Tamariz J Abstract Enantiopure 3-((R)- and 3-((S)-1-phenylethyl)-4-oxazoline-2-ones were evaluated as chiral building blocks for the divergent construction of heterocycles with stereogenic quaternary centers. The N-(R)- or N-(S)-1-phenylethyl group of these compounds proved to be an efficient chiral auxiliary for the asymmetric induction of the 4- and 5-positions of the 4-oxazolin-2-one ring through thermal and MW-promoted nucleophilic conjugated addition to Michael acceptors and alkyl halides. The resulting adducts were transformed via a cascade process into fused six-m...
Source: Chirality - July 18, 2019 Category: Molecular Biology Authors: Santoyo BM, González-Romero C, Zárate-Zárate D, Hernández-Benitez RI, Pelayo V, Barrera E, Escalante CH, Fuentes-Benites A, Martínez-Morales G, López J, Vázquez MA, Delgado F, Jiménez-Vázquez HA, Tamariz J Tags: Chirality Source Type: research

Preparation and chromatographic performance of a multifunctional immobilized chiral stationary phase based on dialdehyde microcrystalline cellulose derivatives.
Abstract A novel high-performance liquid chromatography (HPLC) multifunctional immobilized chiral stationary phase was prepared by bonding dialdehyde microcrystalline cellulose to aminosilica via Schiff base reaction and then derivatized with 3,5-dimethylphenyl isocyanate. The HPLC multifunctional immobilized chiral stationary phase could not only achieve chiral separation but also achieve achiral separation. Chiral separation evaluation showed that 1-(1-naphthyl)ethanol and mandelonitrile got separation in normal phase (NP) mode. Ranolazine, benzoin ethyl ether, metalaxyl, and diclofop were successfully separated...
Source: Chirality - July 18, 2019 Category: Molecular Biology Authors: Gao J, Chen L, Wu Q, Li H, Dong S, Qin P, Yang F, Zhao L Tags: Chirality Source Type: research

Spectroscopy for model heterogeneous asymmetric catalysis.
Abstract Heterogeneous catalysis has vastly benefited from investigations performed on model systems under well-controlled conditions. The application of most of the techniques utilized for such studies is not feasible for asymmetric reactions as enantiomers possess identical physical and chemical properties unless while interacting with polarized light and other chiral entities. A thorough investigation of a heterogeneous asymmetric catalytic process should include probing the catalyst prior to, during, and after the reaction as well as the analysis of reaction products to evaluate the achieved enantiomeric exces...
Source: Chirality - July 18, 2019 Category: Molecular Biology Authors: Kartouzian A Tags: Chirality Source Type: research

Enantioselective hydrogenation of α-ketoesters catalyzed by cinchona alkaloid stabilized Rh nanoparticles in ionic liquid.
Enantioselective hydrogenation of α-ketoesters catalyzed by cinchona alkaloid stabilized Rh nanoparticles in ionic liquid. Chirality. 2019 Jul 16;: Authors: Jiang HY, Xu J, Sun B Abstract The heterogeneous enantioselective hydrogenation of α-ketoesters catalyzed by rhodium nanoparticles (Rh NPs) in ionic liquid was studied with the stabilization and modification of cinchona alkaloids. TEM characterization showed that well-dispersed Rh NPs of about 1.96 nm were obtained in ionic liquid. The results showed that cinchona alkaloids not only had good enantiodifferentiating ability but also...
Source: Chirality - July 16, 2019 Category: Molecular Biology Authors: Jiang HY, Xu J, Sun B Tags: Chirality Source Type: research

Enantioselective synthesis of (R)-Cinacalcet via cobalt-catalysed asymmetric Negishi cross-coupling.
Abstract A novel enantioselective synthesis of (R)-cinacalcet with 99% enantiomeric excesses (ee) has been achieved. The main strategies of the approach include a gram-scale cobalt-catalysed asymmetric cross-coupling of racemic ester with arylzinc reagent, Hoffman-type rearrangement of acidamide, the amidation of chiral amine, and improving the ee of chiral amide from 87% to 99% via recrystallization. PMID: 31310396 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - July 16, 2019 Category: Molecular Biology Authors: Sun X, Wang X, Liu F, Gao Z, Bian Q, Wang M, Zhong J Tags: Chirality Source Type: research

Relationship between enantioselective transformation of racemic quizalofop-ethyl and soil bacterial diversity: A destructive approach.
This study investigated the resilience of bacterial diversity in soils restored after autoclaving, in terms of richness, evenness and community structure, and its feedback on the enantioselective transformation of racemic quizalofop-ethyl (rac-QE). Microbial biomass carbon (MBC) and bacterial richness (indexed by operational taxonomic units [OTUs]) in restored soil recovered to approximately 50% and 29%, respectively, of the native soil within 43 days. Bacterial evenness was much lower in restored soil than in native soil. The relative proportions of dominant bacterial genera differed significantly (P 
Source: Chirality - July 12, 2019 Category: Molecular Biology Authors: Zhou Q, Zhang X, Huang J Tags: Chirality Source Type: research

Effective asymmetric Michael addition of anthrone to nitroalkenes using chiral tetraoxacalix[2]arene[2]triazines as organocatalysts.
Abstract Novel chiral secondary amines bearing a tetraoxacalix[2]arene[2]triazine scaffold were created and used for catalytic asymmetric Michael reaction of anthrone with nitroalkenes. The relevant adducts were obtained in good to excellent yields (82%-98%) and enantioselectivities (75%-98%). PMID: 31294902 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - July 11, 2019 Category: Molecular Biology Authors: Genc HN Tags: Chirality Source Type: research

Separation and determination of tetracycline hydrochloride in real water samples using binary small molecule alcohol-salt aqueous two-phase system coupled with high-performance liquid chromatography.
Abstract An environmental and sensitive sample pretreatment method was established and combined with high-performance liquid chromatography (HPLC) for the analysis of tetracycline hydrochloride (TC) in feed water and lake water. One element small molecule alcohol-salt aqueous two-phase system (ATPS) cannot effectively adjust the polarity of the system, but binary small molecule alcohol-salt ATPS can adjust the polarity and improve the extraction efficiency of antibiotics. In this work, a binary ATPS based on ethanol +2-propanol + (NH4 )2 SO4 system was formed and applied to the separation and purificatio...
Source: Chirality - July 3, 2019 Category: Molecular Biology Authors: Guo DG, Ni L, Wang L, Shao L Tags: Chirality Source Type: research

Separation of ephedrine and pseudoephedrine enantiomers using a polysaccharide-based chiral column: A normal phase liquid chromatography-high-resolution mass spectrometry approach.
Abstract Chiral considerations are found to be very much relevant in various aspects of forensic toxicology and pharmacology. In forensics, it has become increasingly important to identify the chirality of doping agents to avoid legal arguments and challenges to the analytical findings. The scope of this study was to develop an liquid chromatography-mass spectrometry (LCMS) method for the enantiomeric separation of typical illicit drugs such as ephedrines (ie, 1S,2R(+)-ephedrine and 1R,2S(-)-ephedrine) and pseudoephedrine (ie, R,R(-)-pseudoephedrine and S,S(+)-pseudoephedrine) by using normal phase chiral liquid c...
Source: Chirality - June 27, 2019 Category: Molecular Biology Authors: Karakka Kal AK, Karatt TK, Sayed R, Philip M, Meissir S, Nalakath J Tags: Chirality Source Type: research

Synthesis and X-ray diffraction study of a chiral bis-phosphahelicene palladium (II) complex.
Abstract As a complement to our previous studies on the development of a class of chiral phosphahelicenes, this article discloses the synthesis, spectroscopic, and structural characterizations of a new phosphahelicene transition metal complex. It demonstrates the ability of these hindered chiral ligands to coordinate Pd (II) in trans-complexes Cl2 Pd(L*)2 . In the solid state, the complex adopts a C2-symmetric arrangement with two ligands facing each other on the same face of the coordination plane. X-Ray data highlight bending of the Pd (II) unit from the expected planar coordination geometry that might be due to...
Source: Chirality - June 26, 2019 Category: Molecular Biology Authors: Sanogo Y, Aillard P, Retailleau P, Voituriez A, Marinetti A Tags: Chirality Source Type: research

Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic β-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid.
Vibrational circular dichroism as a probe of solid-state organisation of derivatives of cyclic β-amino acids: Cis- and trans-2-aminocyclobutane-1-carboxylic acid. Chirality. 2019 Jun 26;: Authors: Declerck V, Pérez-Mellor A, Guillot R, Aitken DJ, Mons M, Zehnacker A Abstract Peptide models built from cis- and trans-2-aminocyclobutane-1-carboxylic acids (ACBCs) are studied in the solid phase by combining Fourier-transform infrared spectroscopy (FTIR) absorption spectroscopy, vibrational circular dichroism (VCD), and quantum chemical calculations using density functional theory (DFT). The st...
Source: Chirality - June 26, 2019 Category: Molecular Biology Authors: Declerck V, Pérez-Mellor A, Guillot R, Aitken DJ, Mons M, Zehnacker A Tags: Chirality Source Type: research

Novel fluorine-containing chiral hydrazide-hydrazones: Design, synthesis, structural elucidation, antioxidant and anticholinesterase activity, and in silico studies.
In this study, a series of fluorine-containing chiral hydrazide-hydrazone derivatives [III-XII] from ʟ-cysteine ethyl ester hydrochloride was synthesized as new antioxidant and anticholinesterase agents. The antioxidant activity of these derivatives was evaluated by ABTS+· and DPPH· scavenging and CUPRAC assays and the anticholinesterase activity by the Ellman method spectrophotometrically. The results of the antioxidant assay showed that compounds V, IX, and X exhibited higher activity than BHT and α-tocopherol used as positive standards. Among the synthesized derivatives, compound IX (IC50 : 2.3 ...
Source: Chirality - June 20, 2019 Category: Molecular Biology Authors: Sıcak Y, Oruç-Emre EE, Öztürk M, Taşkın-Tok T, Karaküçük-Iyidoğan A Tags: Chirality Source Type: research

Enabling chiral separations in discovery chemistry with open-access chiral supercritical fluid chromatography.
Abstract Work from this paper details a novel walk-up open-access (OA) approach to enable chiral analytical method development and preparative separation of enantiomers in early discovery chemistry using supercritical fluid chromatography (SFC). We have demonstrated the success of this OA approach using immobilized chiral stationary phases (CSPs). After screening a diverse set of racemic drug candidates, we have concluded that a simplified OA chiral SFC platform can successfully purify approximately 60% of the analysed racemates. This streamlined OA workflow enables medicinal chemists with limited expertise in chi...
Source: Chirality - June 13, 2019 Category: Molecular Biology Authors: Michaels P, Neef J, Galyan K, Ginsburg-Moraff C, Zhou X, Dunstan D, Poirier J, Reilly J Tags: Chirality Source Type: research

Design and synthesis of new alkyl-based chiral phosphoric acid catalysts.
Abstract Using chiral BINOL-derived phosphoric acids (PA's) to activate substrates for enhanced reactivity is now regarded as a powerful strategy to control enantioselectivity in asymmetric synthesis. Generally, most substituents at the 3,3'-positions of BINOL PA's are aryl derivatives. These derivatives are pivotal in attaining high selectivity. PA's with alkyl substituents in these positions have rarely been reported. Herein, we introduced alkyl-based substituents at the 3,3'-position of PA's. These new potential catalysts, if applied in reactions, may allow altered noncovalent interactions (as opposed to the ty...
Source: Chirality - June 13, 2019 Category: Molecular Biology Authors: Tang X, He H, Fang X, Chang Z, Antilla JC Tags: Chirality Source Type: research

Enantioselective ene-reduction of E-2-cyano-3-(furan-2-yl) acrylamide by marine and terrestrial fungi and absolute configuration of (R)-2-cyano-3-(furan-2-yl) propanamide determined by calculations of electronic circular dichroism (ECD) spectra.
Abstract This work reports the green organic chemistry synthesis of E-2-cyano-3(furan-2-yl) acrylamide under microwave radiation (55 W), as well as the use of filamentous marine and terrestrial-derived fungi, in the first ene-reduction of 2-cyano-3-(furan-2-yl) acrylamide to (R)-2-cyano-3-(furan-2-yl)propanamide. The fungal strains screened included Penicillium citrinum CBMAI 1186, Trichoderma sp. CBMAI 932 and Aspergillus sydowii CBMAI 935, and the filamentous terrestrial fungi Aspergillus sp. FPZSP 146 and Aspergillus sp. FPZSP 152. A compound with an uncommon CN-bearing stereogenic center at the α-C ...
Source: Chirality - June 13, 2019 Category: Molecular Biology Authors: Jimenez DEQ, Barreiro JC, Dos Santos FM, de Vasconcellos SP, Porto ALM, Batista JM Tags: Chirality Source Type: research

Separation of praziquantel enantiomers using simulated moving bed chromatographic unit with performance designed for semipreparative applications.
Abstract Praziquantel (PZQ) composes a regular medicine available in a tablet form to fight schistosomiasis and just half of its mass is composed by the active principle (L-PZQ), the other half, D-PZQ, is frequently associated to a strong bitter taste. Moreover, optically pure L-PZQ derivatives could be used in studies about adult and juvenile worms' resistance. Nowadays, these studies use racemic PZQ (rac-PZQ) as starting point. The D-PZQ, which would be discarded, could be racemized, coming back as feed concentration in the process. The present work aims to get L-PZQ and D-PZQ with high optical purities (more th...
Source: Chirality - June 11, 2019 Category: Molecular Biology Authors: Cunha FC, Secchi AR, de Souza MB, Barreto AG Tags: Chirality Source Type: research

Efficient racemization of N-phenylacetyl-D-glufosinate for L-glufosinate production.
In this study, optically pure L-glufosinate (L-PPT) was obtained by coupling amidase-mediated hydrolysis of N-phenylacetyl-D,L-glufosinate with racemization of N-phenylacetyl-D-glufosinate (NPDG), which exclusively exhibits effective herbicidal properties compared with its D-enantiomer. To improve the yield of L-PPT, the racemization reaction conditions were optimized, and through single-factor experiments, the optimal reaction temperature, reaction time, and mole ratio of phenylacetic acid to NPDG were determined to be 150°C, 30 minutes, and 1.5, respectively. The response surface methodology was applied to furth...
Source: Chirality - May 28, 2019 Category: Molecular Biology Authors: Xu JM, Li FL, Xue YP, Zheng YG Tags: Chirality Source Type: research

Chiroptical study of cryptophanes subjected to self-encapsulation.
Abstract In 1,1,2,2-tetrachloroethane-d2 , the 129 Xe NMR spectrum of the Xe@cryptophane-223 complex bearing seven acetate groups (Xe@1 complex) shows an unusually broad signal compared with that of its congeners (Chapellet, LL. et al. J. Org. Chem. 2015;80:6143-6151). To interpret this unexpected behaviour, a 1 H NMR analysis and a thorough study of the chiroptical properties of 1 as a function of the nature of the solvent have been performed. The 1 H NMR spectra of 1 reveal that a self-encapsulation phenomenon takes place in DMSO-d6 and 1,1,2,2-tetrachloroethane-d2 solvents. Thanks to the separation of the two e...
Source: Chirality - May 28, 2019 Category: Molecular Biology Authors: Baydoun O, Buffeteau T, Daugey N, Jean M, Vanthuyne N, Chapellet LL, De Rycke N, Brotin T Tags: Chirality Source Type: research

Deviations from Beer's law in electronic absorption and circular dichroism: Detection for enantiomeric excess analysis.
Abstract The electronic absorption (UV) to circular dichroism (CD) signal ratio can be used for enantiomeric excess (ee) analysis within linear range. However, CD detection often requires a high sample concentration where deviations from Beer's law may occur. Individual enantiomers of four chiral compounds were separated from commercial racemates by semipreparative high-performance liquid chromatography (HPLC) with chiral columns. They were used to trace possible deviations in both UV and CD detection on achiral HPLC with a photodiode array detector and a CD detector. The CD/UV ratios for samples with the same ee ...
Source: Chirality - May 21, 2019 Category: Molecular Biology Authors: Tang Q, Zhao L, Xie J, Liu K, Liu W, Zhou S Tags: Chirality Source Type: research

Enantioseparation and molecular modeling study of five β-adrenergic blockers on Chiralpak IC column.
Enantioseparation and molecular modeling study of five β-adrenergic blockers on Chiralpak IC column. Chirality. 2019 May 21;: Authors: Zhao Y, Li S, Wang X, Yu J, Song Y, Guo X Abstract A new high-performance liquid chromatography (HPLC) method was developed for the enantiomeric resolution of five β-adrenergic blockers on a Chiralpak IC column (250 mm × 4.6 mm, 5.0 μm particle size) in normal phase mode. The mobile phase used was n-hexane-ethanol-diethylamine in different proportions at the flow rate of 1.0 mL/min with the column temperature of 25°C...
Source: Chirality - May 21, 2019 Category: Molecular Biology Authors: Zhao Y, Li S, Wang X, Yu J, Song Y, Guo X Tags: Chirality Source Type: research

Direct enantioselective vinylogous Mannich-type reactions of acyclic enals: New experimental insights into the E/Z-dilemma.
Abstract The direct heterofunctionalization of acyclic α,β-unsaturated aldehydes with N-acylquinolinium ions contemplating the formation of two stereocentres is studied using dienamine catalysis. This work gives some new experimental insights on the remote stereocontrol in dienamine catalysis using unbiased aliphatic systems and large electrophiles, pointing to a (Z)-preference of the reactive configuration of the second double bond. PMID: 31090981 [PubMed - as supplied by publisher] (Source: Chirality)
Source: Chirality - May 15, 2019 Category: Molecular Biology Authors: Vargiu M, Favero L, Menichetti A, Di Bussolo V, Marchetti F, Pescitelli G, Di Pietro S, Pineschi M Tags: Chirality Source Type: research

The biological activities of prothioconazole enantiomers and their toxicity assessment on aquatic organisms.
Abstract Chiral fungicide prothioconazole has a wide range of antifungal spectrum; however, little research has been conducted to evaluate prothioconazole on an enantiomeric level. Five target pathogens and three common aquatic organisms were tested for the enantioselective bioactivity and toxicity of prothioconazole in this work. The antifungal activity of the enantiomers against wheat phytoalexin, rice blast fungus, exserohilum turcicum, Alternaria triticina, and Fusarium avenaceum was determined, and it was found that (-)-prothioconazole were 85 to 2768 times more active than (+)-prothioconazole toward these ta...
Source: Chirality - May 8, 2019 Category: Molecular Biology Authors: Zhai W, Zhang L, Cui J, Wei Y, Wang P, Liu D, Zhou Z Tags: Chirality Source Type: research

Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid-liquid extraction.
Abstract Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activities. It has important practical values to obtain optically pure S-flurbiprofen. In this work, chiral ionic liquids, which have good structural designability and chiral recognize ability, were selected as the extraction selector by the assistance of quantum chemistry calculations. The distributi...
Source: Chirality - May 7, 2019 Category: Molecular Biology Authors: Cui X, Ding Q, Shan RN, He CH, Wu KJ Tags: Chirality Source Type: research

Enantiomeric resolution, thermodynamic parameters, and modeling of clausenamidone and neoclausenamidone on polysaccharide-based chiral stationary phases.
Abstract The aim of the paper is to describe a new synthesis route to obtain synthetic optically active clausenamidone and neoclausenamidone and then use high-performance liquid chromatography (HPLC) to determine the optical purities of these isomers. In the process, we investigated the different chromatographic conditions so as to provide the best separation method. At the same time, a thermodynamic study and molecular simulations were also carried out to validate the experimental results; a brief probe into the separation mechanism was also performed. Two chiral stationary phases (CSPs) were compared with separa...
Source: Chirality - April 24, 2019 Category: Molecular Biology Authors: Luo X, Fang C, Mi J, Xu J, Lin H Tags: Chirality Source Type: research

Synthesis of novel chiral metal complexes derived from chiral thiosemicarbazide ligands as potential antioxidant agents.
ouml;nmez M, Öztürk M Abstract Two new chiral thiosemicarbazide ligands and their Cu (II), Ni (II), Pd (II), and Zn (II) complexes were synthesized and characterized by nuclear magnetic resonance (NMR) (only for ligand), Fourier transform infrared (FT-IR), ultraviolet visible (UV-Vis), mass, and elemental analysis. The antioxidant activity of ligands and their metal complexes was examined. It was found that the antioxidant activity of metal complexes was better than their ligands. In addition, the antioxidant activity, as reflected by free radical scavenging, was evaluated. Besides, Pd (II) complexes exh...
Source: Chirality - April 11, 2019 Category: Molecular Biology Authors: Başaran E, Sıcak Y, Sogukomerogullari HG, Karaküçük-Iyidoğan A, Oruç-Emre EE, Sönmez M, Öztürk M Tags: Chirality Source Type: research