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Advances in Enantioselective Syntheses and Chiral Separations

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Chemistry".

Deadline for manuscript submissions: closed (30 April 2021) | Viewed by 14288

Special Issue Editor

1. Division of Organic Chemistry, Centre of Molecular and Macromolecular Studies, Sienkiewicza 112, 90-363 Łódź, Poland
2. Institute of Chemistry, Jan Dlugosz University in Czestochowa, Armii Krajowej 13/15, 42-200 Czestochowa, Poland
Interests: heterorganic compounds; stereochemistry; synthetic methodology; asymmetric synthesis; supramolecular chemistry; new materials; spectroscopy
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Special Issue Information

Dear Colleagues,

For many years, the major factor stimulating the search for optically active compounds was the interest in static and dynamic stereochemistry of organic derivatives with various elements of stereogenity, commonly used as models in mechanistic studies. The search for new enantioselective syntheses and enantioselective separation procedures has been stimulated by the rapid development of medicinal chemistry and biochemistry and, in particular, the needs of the pharmaceutical industry, which is now obliged to study very deeply the biological activity of enantiomeric forms of all chiral drugs before their introduction to the market. This Special Issue will provide a contemporary overview of progress on these two topics. From fundamental aspects to applications, any works related to the generation of new stereogenic units based on chemical and chemoenzymatic methodology are thus welcome. In many cases, when enantioselective synthesis cannot be used to obtain optically active derivatives, chiral separation on a preparative scale remains the method of choice. In addition, analytical chiral separation plays a very important role as a tool that allows very fast and accurate determination of enantiomeric excesses of optically active products isolated by various enantioselective procedures and optically active substances isolated from natural sources. Therefore, all contributions dealing with the analytical aspects of chiral separation are also warmly welcome.

Prof. Józef Drabowicz
Guest Editor

Manuscript Submission Information

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Keywords

  • absolute configuration
  • asymmetric synthesis
  • chiral chromatography
  • chirality
  • diastereoisomers
  • dynamic kinetic resolution
  • elements of stereogenicity enantiomeric excess
  • enantiomers
  • racemization

Published Papers (4 papers)

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Research

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19 pages, 6467 KiB  
Article
Resolution of P-Sterogenic 1-Phenylphosphin-2-en-4-one 1-Oxide into Two Enantiomers by (R,R)-TADDOL and Conformational Diversity of the Phosphinenone Ring and TADDOL in the Crystal State
Molecules 2021, 26(22), 6873; https://doi.org/10.3390/molecules26226873 - 15 Nov 2021
Viewed by 1714
Abstract
The resolution of racemic 1-phenylphosphin-2-en-4-one 1-oxide (2), was achieved through the fractional crystallization of its diastereomeric complexes with (4R,5R)-(−)-2,2-dimethyl -α,α,α′,α′-tetraphenyl-dioxolan-4,5-dimethanol (R,R-TADDOL) followed by the liberation of the individual enantiomers of 2 by flash chromatography on [...] Read more.
The resolution of racemic 1-phenylphosphin-2-en-4-one 1-oxide (2), was achieved through the fractional crystallization of its diastereomeric complexes with (4R,5R)-(−)-2,2-dimethyl -α,α,α′,α′-tetraphenyl-dioxolan-4,5-dimethanol (R,R-TADDOL) followed by the liberation of the individual enantiomers of 2 by flash chromatography on silica gel columns. The resolution process furnished the two enantiomers of 2 of 99.1 and 99.9% e.e. at isolated yields of 62 and 59% (counted for the single enantiomer), respectively. The absolute configurations of the two enantiomers were established by means of X-ray crystallography of their diastereomerically pure complexes, i.e., (R)-2R,R)-TADDOL and (S)-2•(R,R)-TADDOL. The structural analysis revealed that in the (R)-2•(R,R)-TADDOL complex, the P-phenyl substituent occupied a pseudoequatorial position, whereas in (S)-2•(R,R)-TADDOL, it appeared in both the pseudoequatorial and the pseudoaxial positions in four symmetrically independent molecules. Concurrent conformational changes of the TADDOL molecules were best described by the observed changes of a pseudo-torsional CO...OC angle that could be considered as a possible measure of TADDOL conformation in its receptor–ligand complexes. The structural analysis of the (R,R)-TADDOL molecule revealed that efficiency of this compound for use as an effective resolving factor comes from its ability to flexibly fit its structure to both enantiomers of a ligand molecule, producing a rare case of resolution for both pure enantiomers with one chiral separating agent. The resolved (R)-2 was used to assign the absolute configuration of a recently described (−)-1-phenylphosphin-2-en-4-one 1-sulfide by chemical correlation. In addition, an attempted stereoretentive reduction of (R)-2 by PhSiH3 at 60 °C revealed an unexpectedly low barrier for P-inversion in 1-phenylphosphin-2-en-4-one. Full article
(This article belongs to the Special Issue Advances in Enantioselective Syntheses and Chiral Separations)
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11 pages, 2642 KiB  
Article
Diastereoisomerically Pure, (S)-O-1,2-O-isopropyli dene-(5-O-α-d-glucofuranosyl) t-butanesulfinate: Synthesis, Crystal Structure, Absolute Configuration and Reactivity
Molecules 2020, 25(15), 3392; https://doi.org/10.3390/molecules25153392 - 27 Jul 2020
Viewed by 1682
Abstract
The reaction of t-butylmagnesium chlorides with diastereomerically pure (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-α-d-glucofuranose (R)-4 was found to be stopped at the stage of the corresponding, diastereoisomerically pure 1,2-O-isopropylidene-(5-O-α-d-glucofuranosyl) t [...] Read more.
The reaction of t-butylmagnesium chlorides with diastereomerically pure (R)-1,2-O-isopropylidene-3,5-O-sulfinyl-α-d-glucofuranose (R)-4 was found to be stopped at the stage of the corresponding, diastereoisomerically pure 1,2-O-isopropylidene-(5-O-α-d-glucofuranosyl) t-butanesulfinate (S)-10 for which the crystal structure and the (S)-absolute configuration was determined by X-ray crystallography. Comparison of the absolute configurations of the starting sulfite (R)-4, and t-butanesulfinate (S)-10 (which crystallizes in the orthorhombic system, space group P212121, with the single compound molecule present in the asymmetric unit), clearly indicates that the reaction of nucleophilic substitution at the stereogenic sulfur atom in the sulfite (R)-4 occurs with the full inversion of configuration via the trigonal bipyramidal sulfurane intermediate 4c in which both the entering and leaving groups are located in apical positions. Full article
(This article belongs to the Special Issue Advances in Enantioselective Syntheses and Chiral Separations)
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Review

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30 pages, 5965 KiB  
Review
Chiral Recognition for Chromatography and Membrane-Based Separations: Recent Developments and Future Prospects
Molecules 2021, 26(4), 1145; https://doi.org/10.3390/molecules26041145 - 21 Feb 2021
Cited by 33 | Viewed by 6033
Abstract
With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug [...] Read more.
With the rapid development of global industry and increasingly frequent product circulation, the separation and detection of chiral drugs/pesticides are becoming increasingly important. The chiral nature of substances can result in harm to the human body, and the selective endocrine-disrupting effect of drug enantiomers is caused by differential enantiospecific binding to receptors. This review is devoted to the specific recognition and resolution of chiral molecules by chromatography and membrane-based enantioseparation techniques. Chromatographic enantiomer separations with chiral stationary phase (CSP)-based columns and membrane-based enantiomer filtration are detailed. In addition, the unique properties of these chiral resolution methods have been summarized for practical applications in the chemistry, environment, biology, medicine, and food industries. We further discussed the recognition mechanism in analytical enantioseparations and analyzed recent developments and future prospects of chromatographic and membrane-based enantioseparations. Full article
(This article belongs to the Special Issue Advances in Enantioselective Syntheses and Chiral Separations)
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35 pages, 25500 KiB  
Review
New Advances in the Synthetic Application of Enantiomeric 1-Phenylethylamine (α-PEA): Privileged Chiral Inducer and Auxiliary
Molecules 2020, 25(21), 4907; https://doi.org/10.3390/molecules25214907 - 23 Oct 2020
Cited by 7 | Viewed by 4289
Abstract
New developments in the synthesis, resolution, and synthetic applications of chiral 1-phenylethylamine (α-PEA) reported in the last decade have been reviewed. In particular, improvements in the synthesis of α-PEA and its derivatives and chiral resolution, as well as their applications in the resolution [...] Read more.
New developments in the synthesis, resolution, and synthetic applications of chiral 1-phenylethylamine (α-PEA) reported in the last decade have been reviewed. In particular, improvements in the synthesis of α-PEA and its derivatives and chiral resolution, as well as their applications in the resolution of other compounds, were discussed. α-PEA was used as a chiral auxiliary in the diastereoselective synthesis of medicinal substances and natural products. Chiral ligands with α-PEA moieties were applied in asymmetric reactions, and effective modular chiral organocatalysts were constructed with α-PEA fragments and used in important synthetic reactions. Full article
(This article belongs to the Special Issue Advances in Enantioselective Syntheses and Chiral Separations)
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