Trityl Ethers: Molecular Bevel Gears Reporting Chirality through Circular Dichroism Spectra

Ściebura, Jacek; Skowronek, Paweł; Gawroński, Jacek

doi:10.1002/ange.200902167

Cited by 23 publications

(18 citation statements)

References 37 publications

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“…It is well known that phenyl rings in the trityl group can adopt a propeller conformation, thus forming enantiomeric structures of P or M helical chirality. The hydroxyl group rotamers are determined by the C3‐C4‐O‐H dihedral angle, while rotamers of the trityl group by dihedral angles ω 1 –ω 3 defined by Gawronski et al based on the differences in the relative positions of the three phenyls. Thus, besides differences associated with the C4 hydroxyl group rotamers, all these conformers represent two types concerning the helicity of trityl substituent, adopting either MPM or PMP conformation (Figures and S5).…”

Section: Resultsmentioning

confidence: 99%

Circular dichroism spectroscopy and DFT calculations in determining absolute configuration and E/Z isomers of conjugated oximes

Rode

Frelek

2017

Chirality

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The primary purpose of this work was to demonstrate the suitability of circular dichroism (CD) spectroscopy in stereochemical studies of α,β-unsaturated oximes, with particular emphasis on determination of E and Z geometry of the oxime double bond. As models for this study, O-phenyl and O-triphenylmethyl (trityl) oximes of 4-hydroxy-2-methylcyclopent-2-en-1-one were selected. These model compounds differ in both absolute configuration at C4 carbon atom and E-Z configuration of the oxime double bond. The basic dichroic technique applied was electronic circular dichroism (ECD) assisted by quantum-chemical calculations and vibrational circular dichroism (VCD) for selected cases. Such an approach enabled effective implementation of both goals. Thus, we were able to associate the signs of Cotton effects in the range of 190-240 nm with the absolute configuration at C4 and within 240-300 nm with the E- or Z-geometry of the oxime double bond. Within this work, optical activity of the protecting trityl group was also studied towards formation of the propeller-shaped conformations by using the same combined CD/DFT methodology. As shown, the helical structure of the trityl group has a considerable influence on the ECD spectra. However, the MPM and PMP conformers of the trityl group are in fact almost equally populated in the conformational equilibrium, making it impossible to distinguish them. On the other hand, rotamers of the hydroxyl group at C4 show a decisive impact on the VCD spectra in both phenoxy and trityl oximes.

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Section: Resultsmentioning

confidence: 99%

Circular dichroism spectroscopy and DFT calculations in determining absolute configuration and E/Z isomers of conjugated oximes

Rode

Frelek

2017

Chirality

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“…The large majority of CD sensing assays introduced so far relies on the formation of supramolecular assemblies, metal coordination complexes, hydrogen bond adducts, or dynamic covalent chemistry (DCC) . In addition, stereodynamic probes that undergo irreversible covalent bond formation with a chiral analyte to generate a CD signal that can be used for absolute configuration and ee determination have been developed by several groups . Nevertheless, reversible Schiff base formation with chiral amines has become a very popular and highly successful CD sensing strategy .…”

Section: Introductionmentioning

confidence: 99%

Stereochemical analysis of chiral amines, diamines, and amino alcohols: Practical chiroptical sensing based on dynamic covalent chemistry

2020

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Practical chiroptical sensing with a small group of commercially available aromatic aldehydes is demonstrated. Schiff base formation between the electron‐deficient 2,4‐dinitrobenzaldehyde probe and either primary amines, diamines, or amino alcohols proceeds smoothly in chloroform at room temperature and is completed in the presence of molecular sieves within 2.5 hours. The substrate binding coincides with a distinct circular dichroism signal induction at approximately 330 nm, which can be correlated to the absolute configuration and enantiomeric composition of the analyte. The usefulness of this sensing method is highlighted with the successful sensing of 18 aliphatic and aromatic amines and amino alcohols and five examples showing quantitative %ee determination with good accuracy.

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“…A variety of circular dichroism (CD) probes that accomplish determination of both the enatiomeric excess (ee) and the absolute configuration have been developed. Contributions to this field demonstrating the general utility of carefully designed CD reporter moieties that are covalently attached to an analyte have come out of Gawronski's and other groups . Throughout the last 20 years, Berova and Nakanishi, Borhan, Canary, Anslyn, and other groups have introduced powerful chiroptical assays that can be used to concurrently determine the ee and absolute configuration of a broad pool of chiral compounds.…”

Section: Introductionmentioning

confidence: 99%

Chirality sensing with stereodynamic copper(I) complexes

2017

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Three Cu(I) complexes derived from stereodynamic diphosphine ligands were synthesized and used for chirality sensing. The coordination of diamines and amino acids to these complexes generates distinct circular dichroism signals. The chiroptical sensor response allows determination of the absolute configuration and the enantiomeric excess of the analyte at low concentrations. This method is operationally simple, fast, and attractive for high-throughput sensing applications.

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Trityl Ethers: Molecular Bevel Gears Reporting Chirality through Circular Dichroism Spectra

Cited by 23 publications

References 37 publications

Circular dichroism spectroscopy and DFT calculations in determining absolute configuration and E/Z isomers of conjugated oximes

Circular dichroism spectroscopy and DFT calculations in determining absolute configuration and E/Z isomers of conjugated oximes

Stereochemical analysis of chiral amines, diamines, and amino alcohols: Practical chiroptical sensing based on dynamic covalent chemistry

Chirality sensing with stereodynamic copper(I) complexes

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