Multiwavelength Optical Rotation Detection: An Effective Approach for the Recognition of Analytical and Semi-Preparative HPLC Enantioseparation of the Chiral Pheromone Olean and Its Stereochemical Characterization.

Olean is the chiral spiroacetal sex pheromone of the female olive fruit fly Bactrocera oleae. Laboratory tests have demonstrated that the (R)-(-)-olean enantiomer is active on males, whereas females respond to (S)-(+)-olean. Here we present the first HPLC enantioseparation of olean using polysaccharide derivatives as chiral stationary phases and a polarimetric detector equipped with a micro-flow cell capable of detecting optical rotation at six different wavelengths.

Inherently Chiral Oligomers Based on Indole-Benzothiophene Core.

In recent years, transductors of chiral information based on conducting polymers have gained considerable attention. In particular, inherently chiral materials, which allow differentiation between the antipodes of a chiral analyte in terms of energetic variations, are highly desired. In this work, we successfully synthesized a novel inherently chiral oligomer based on an indole-benzothiophene core, namely, 2-([2,2'-bithiophen]-5-yl)-3-(2-([2,2'-bithiophen]-5-yl)benzo[b]thiophen-3-yl)-N-methylindole (BTIndT).

Wireless asymmetric umpolung electrosynthesis.

Electroorganic synthesis has become an exciting tool for the asymmetric conversion of pro-chiral compounds. Herein, we introduced a wireless methodology based on bipolar electrochemistry in synergy with the enantioselective capabilities of inherently chiral oligomers to induce an umpolung chirality transfer. This was exemplified by the electro-conversion of a racemic mixture of lansoprazole to an -enriched solution of a single antipode.

Chiral Hydroxy Metabolite of Mebendazole: Analytical and Semi-Preparative High-Performance Liquid Chromatography Resolution and Chiroptical Properties.

Mebendazole () is a benzimidazole carbamate anthelmintic used worldwide for the treatment and prevention of parasitic disorders in animals and humans. A large number of in vivo and in vitro studies have demonstrated that also has anticancer activity in multiple types of cancers. After oral administration, the phenylketone moiety of is rapidly reduced to the hydroxyl group to form the chiral hydroxy metabolite ().

Green HPLC Enantioseparation of Chemopreventive Chiral Isothiocyanates Homologs on an Immobilized Chiral Stationary Phase Based on Amylose tris-[()-α-Methylbenzylcarbamate].

Sulforaphane is a chiral phytochemical with chemopreventive properties. The presence of a stereogenic sulfur atom is responsible for the chirality of the natural isothiocyanate. The key role of sulfur chirality in biological activity is underscored by studies of the efficacy of individual enantiomers as chemoprotective agents.

Enantioselective high-performance liquid chromatography combined with spectroscopic methods and theoretical calculations: A valid strategy to determine the absolute configuration of eugenol derivatives.

The absolute configuration of three chiral eugenol derivatives was assigned by a multi-step methodology based on enantioselective HPLC combined with spectroscopic and theoretical calculations. Milligram amounts of enantiopure forms used for stereochemical characterization were isolated by HPLC on the immobilized amylose-based chiral stationary phase Chiralpak IG using normal phase elution conditions. The absolute configuration was indirectly determined for one of the three compounds by H NMR via methoxy-α-trifluoromethyl-α-phenylacetic acid derivatization (Mosher's acid).

Designing Powerful Biindole-Based Inherently Chiral Selectors: Enhancing Enantiodiscrimination by Core Functionalization with Additional Coordination Elements.

Among inherently chiral selectors of axial stereogenicity, usually resulting in very good enantiodiscrimination performances, the biindole-based family has the additional advantage of very easy functionalization of the two nitrogen atoms with a variety of substituents with desirable properties. Aiming to evaluate the possibility of exploiting such feature to enhance the enantiodiscrimination ability of the archetype structure, a series of three inherently chiral monomers were designed and synthesized, characterised by a 2,2'-biindole atropisomeric core conjugated to bithiophene wings enabling fast and regular electrooligomerization, and functionalised at the nitrogen atoms with an ethyl, a methoxyethyl, or a hydroxyethyl substituent. Nitrogen alkylation was also exploited to obtain for the first time the chemical resolution of the biindole selectors without employing chiral HPLC.

Wireless Hollow Miniaturized Objects for Electroassisted Chiral Resolution.

Chiral resolution plays a crucial role in the field of drug development, especially for a better understanding of biochemical processes. In such a context, classic separation methods have been used for decades due to their versatility and easy scale-up. Among the many attempts proposed for enantioselective separation, electroassisted methods are presented as an interesting alternative.

Miniaturized enantioselective tubular devices for the electromechanical wireless separation of chiral analytes.

Chirality plays a crucial role in different research fields, ranging from fundamental physico-chemistry to applied aspects in materials science and medicine. In this context, enantioselective loading and pumping of chiral analytes for analysis, separation, and cargo delivery applications is an interesting scientific challenge. Herein, we introduce artificial chiral soft electromechanical pumps based on a bi-layer film built up by electrodepositing polypyrrole and an inherently chiral conducting oligomer at its internal surface.

Virtual chiral recognition of eugenol derivatives on amylose tris(3-chloro-5-methylphenylcarbamate) chiral stationary phase in unusual normal-phase mode.

Chromatographic enantioseparation on polysaccharide-based chiral stationary phases has undergone explosive development over the last three decades as a method for separating the enantiomers of chiral compounds on an analytical and preparative scale. In this context, understanding the nature of the intermolecular interactions involved in retention and recognition processes is an interesting scientific challenge. In the present study, three eugenol derivatives were used as chiral references to elucidate some unexplored aspects of the enantioselective and retention properties of the Chiralpak IG-U chiral stationary phase based on amylose-tris(3-chloro-5-methylphenylcarbamate).

Kinetic Study on the Base-Catalyzed Imine-Enamine Tautomerism of a Chiral Biologically Active Isoxazoline Derivative by HPLC on Amylose Tris(3,5-dimethylphenylcarbamate) Chiral Stationary Phase.

Isoxazoline is a nitrogen- and oxygen-containing five-membered heterocyclic scaffold with diverse biological profiles such as antimicrobial, fungicidal, anticancer, antiviral, analgesic and anti-inflammatory activity. Accordingly, the use of this peculiar structural framework in drug discovery is a successful strategy for the development of new drug candidates. Here, a chiral saccharin/isoxazoline hybrid was considered to investigate the tendency of the imine moiety of the heterocyclic ring to tautomerize to the enamine form in the presence of a basic catalyst.

Insight into the photolytic degradation products of Rosuvastatin: Full chiral and structural elucidation and conversion kinetics by a combined chromatographic, spectroscopic and theoretical approach.

Rosuvastatin (RSV) is a well-established lipid-lowering drug. RSV is susceptible to degradation under various stress conditions and forms two cyclic derivatives by a radical-mediated photolytic mechanism. On a structural basis, these epimeric compounds (reported as FP-B in the European Pharmacopeia monograph Rosuvastatin tablets) retain the configuration of the stereogenic carbons of RSV (3R,5S) and have opposite absolute configurations at the third stereogenic center.

Enantioselective resolution of two model amino acids using inherently chiral oligomer films with uncorrelated molecular structures.

Preferential crystallization induced by chiral surfaces is an interesting alternative to isolate enantiopure antipodes. Herein, we take advantage of the outstanding enantiorecognition capabilities of inherently chiral oligomers to induce an enantioselective crystallization process. We exemplify this strategy with two amino acid model molecules, asparagine and glutamic acid, having a completely uncorrelated structure with respect to the template.

Magnetic field-enhanced redox chemistry on-the-fly for enantioselective synthesis.

Chemistry on-the-fly is an interesting concept, extensively studied in recent years due to its potential use for recognition, quantification and conversion of chemical species in solution. In this context, chemistry on-the-fly for asymmetric synthesis is a promising field of investigation, since it can help to overcome mass transport limitations, present for example in conventional organic electrosynthesis. Herein, the synergy between a magnetic field-enhanced self-electrophoretic propulsion mechanism and enantioselective redox chemistry on-the-fly is proposed as an efficient method to boost stereoselective conversion.

Chemo- and enantio-selective reversed-phase HPLC analysis of rosuvastatin using a cellulose-based chiral stationary phase in gradient elution mode.

A direct reversed-phase high-performance liquid chromatographic (HPLC) method was developed for determining the content of the enantiomeric impurity of the chiral statin rosuvastatin calcium salt (RSV) in commercial tablets. The baseline enantioseparation was achieved using the Lux Cellulose-2 column and a binary linear gradient of acetonitrile and trifluoroacetic acid 0.05% in an aqueous solution.

A Novel Validated UHPLC Method for the Estimation of Rosuvastatin and Its Complete Impurity Profile in Tablet Formulations.

A key step in the development of medicinal products is the research and validation of selective and sensitive analytical methods for the control of impurities from synthesis and degradation. As most impurities are similar in structure to the drug substance, the achievement of chemo-selective conditions is usually challenging. Herein, a direct and highly selective ultra-high-performance liquid chromatographic method for determining the assay and related substances content in medicinal products containing rosuvastatin calcium salt (RSV) is presented.

Wireless electromechanical enantio-responsive valves.

Microfluidic valves based on chemically responsive materials have gained considerable attention in recent years. Herein, a wireless enantio-responsive valve triggered by bipolar electrochemistry combined with chiral recognition is reported. A conducting polymer actuator functionalized with the enantiomers of an inherently chiral oligomer was used as bipolar valve to cover a tube loaded with a dye and immersed in a solution containing chiral analytes.

HPLC Enantioseparation of Rigid Chiral Probes with Central, Axial, Helical, and Planar Stereogenicity on an Amylose (3,5-Dimethylphenylcarbamate) Chiral Stationary Phase.

The chiral resolving ability of the commercially available amylose (3,5-dimethylphenylcarbamate)-based chiral stationary phase (CSP) toward four chiral probes representative of four kinds of stereogenicity (central, axial, helical, and planar) was investigated. Besides chirality, the evident structural feature of selectands is an extremely limited conformational freedom. The chiral rigid analytes were analyzed by using pure short alcohols as mobile phases at different column temperatures.

Bipolar electrochemical rotors for the direct transduction of molecular chiral information.

Efficient monitoring of chiral information of bioactive compounds has gained considerable attention, due to their involvement in different biochemical processes. In this work, we propose a novel dynamic system for the easy and straightforward recognition of chiral redox active molecules and its possible use for the efficient measurement of enantiomeric excess in solution. The approach is based on the synergy between the localized enantioselective oxidation of only one of the two antipodes of a chiral molecule and the produced charge-compensating asymmetric proton flux along a bipolar electrode.

Kinetic and mechanism study of the spontaneous, solvent- and base-catalyzed degradation of the precursor of the β-nitro alcohol metaraminol by combining HPLC/electronic circular dichroism/theoretical methods.

Chiral β-nitro alcohols are key intermediates in the synthesis of a wide range of active pharmaceutical ingredients. Despite their massive use for pharmaceutical applications, in-depth kinetics studies concerning their stability during formation and transformation reactions are scarce in the literature. In this study, the (1R,2S)-1-(m-benzyloxy)-2-nitro-1-propanol) (BNA), the precursor of the metaraminol, was selected as a molecular model and the retro-Henry reaction was explored by a multidisciplinary approach involving HPLC, electronic circular dichroism and theoretical methods.

Autonomous Chiral Microswimmers with Self-mixing Capabilities for Highly Efficient Enantioselective Synthesis.

The development of chiral catalysts plays a very important role in various areas of chemical science. Heterogeneous catalysts have the general advantage of allowing a more straightforward separation from the products. One specific case of heterogeneous catalysis is electrocatalysis, being potentially a green chemistry approach.

ON/OFF receptor-like enantioseparation of planar chiral 1,2-ferrocenes on an amylose-based chiral stationary phase: The role played by 2-propanol.

A set of nine planar chiral 1,2-ferrocenes was analyzed by high-performance liquid chromatography (HPLC) on the amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase. The enantioseparations were carried out using neat methanol, ethanol, 1-propanol, and 2- propanol as well as mixtures of n-hexane-2-propanol as mobile phases. The differences in retention times between the second eluted (Rp)-enantiomers and the first eluted (Sp)-enantiomers were significantly influenced by elution modes and the steric hindrance of substituents at the aromatic rings of the ferrocene backbone.

Anticancer Activity of ()-5-Chloro-3-((3,5-dimethylphenyl)sulfonyl)--(1-oxo-1-((pyridin-4-ylmethyl)amino)propan-2-yl)-1-indole-2-carboxamide (RS4690), a New Dishevelled 1 Inhibitor.

Wingless/integrase-11 (WNT)/β-catenin pathway is a crucial upstream regulator of a huge array of cellular functions. Its dysregulation is correlated to neoplastic cellular transition and cancer proliferation. Members of the Dishevelled (DVL) family of proteins play an important role in the transduction of WNT signaling by contacting its cognate receptor, Frizzled, via a shared PDZ domain.

Enantioselective HPLC analysis of escitalopram oxalate and its impurities using a cellulose-based chiral stationary phase under normal- and green reversed-phase conditions.

Normal-phase and reversed-phase high-performance liquid chromatography methods for the separation of the active pharmaceutical ingredient escitalopram from its (R)-enantiomer impurity have been developed on the cellulose-based Chiralcel OJ-H chiral stationary phase. Both methods share two features: they use ethanol as a cosolvent and are able to give a complete enantioseparation without interference from other associated chiral impurities. With the green eluent mixture ethanol-water-diethylammine 70:30:0.

Bipolar Electrochemical Measurement of Enantiomeric Excess with Inherently Chiral Polymer Actuators.

Straightforward enantioselective analytical methods are very important for drug safety, considering that in certain cases one of the two enantiomers of a chiral molecule might be harmful for humans. In this work, we propose a simple system for the direct and easy read-out of the enantiomeric excess of 3,4-dihydroxyphenylalanine (DOPA) as a model analyte. A conducting oligomer, i.