Absolute configurations of phytotoxic inuloxins B and C based on experimental and computational analysis of chiroptical properties

Evidente, Marco; Santoro, Ernesto; Petrovic, Ana G.; Cimmino, Alessio; Koshoubu, Jun; Evidente, Antonio; Berova, Nina; Superchi, Stefano

doi:10.1016/j.phytochem.2016.07.012

Cited by 28 publications

(30 citation statements)

References 23 publications

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“…Inuloxin C was purified from the organic extract of the aerial parts of I. viscosa as previously reported …”

Section: Methodsmentioning

confidence: 99%

“…This activity was also preserved by inuloxin C as well as inuloxins A and D . As the relation between absolute configuration (AC) and the biological activity and mode of action of natural compounds, including bio‐pesticides was extensively reported, the ACs of inuloxins A‐C were previously studied by chiroptical methods …”

Section: Introductionmentioning

confidence: 99%

“…The structure and relative configuration of inuloxin C was determined through NMR analysis . Using the relative configuration determined from NMR, the AC of inuloxin C was assigned as (5 S ,7 S ,8 S ,10 S ) (see Figure ) based on the comparison of the experimental electronic circular dichroism (ECD) and optical rotatory dispersion (ORD) data with corresponding QC calculations carried out for only one diastereomer …”

Section: Introductionmentioning

confidence: 99%

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Absolute configurations of chiral molecules with multiple stereogenic centers without prior knowledge of the relative configurations: A case study of inuloxin C

et al. 2018

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Electronic circular dichroism (ECD) and discrete wavelength resolved specific optical rotations, referred to as optical rotatory dispersion (ORD), have been remeasured for inuloxin C and analysed with corresponding quantum chemical (QC) predicted data for all diastereomers of inuloxin C. The QC‐predicted sign of ORD and of a major ECD band are found to match the experimental observations for more than one diastereomer. However, these ECD and ORD analyses combined with electronic dissymmetry factor analyses narrowed the choices of absolute configuration (AC) of inuloxin C to (5R,7S,8R,10R) and (5S,7S,8S,10S). Supplementing these analyses with corresponding analyses for acetylated inuloxin C resulted in a unique choice for the AC of inuloxin C as (5S,7S,8S,10S). This result is independent of NMR analysis. Furthermore, this AC is in full agreement with previously determined relative configuration by NMR and the AC derived therefrom using ECD and ORD. Therefore, the present study identifies a pathway for determining the ACs of chiral molecules with multiple stereogenic centers when relative configurations are not known, or when it is desired to deduce ACs independent of the known relative configurations.

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“…Inuloxin C was purified from the organic extract of the aerial parts of I. viscosa as previously reported …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Absolute configurations of chiral molecules with multiple stereogenic centers without prior knowledge of the relative configurations: A case study of inuloxin C

et al. 2018

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“…In the current literature, there is a strong trend to use two or more distinct chiroptical methods for the determination of the absolute configuration of chiral molecules, having both natural and synthetic origin . In our previous works on aryl benzyl sulfoxides, we employed solely ECD.…”

Section: Resultsmentioning

confidence: 99%

“…Finally, our study attempts to clarify the necessity of the use of two (or more) different chiroptical methods for determining absolute configurations, which is at present a common tactic used by many authors . To do so, first we recorded ECD and VCD spectra in solution, and in the next step quantum‐chemical calculations of ECD and VCD spectra were carried out.…”

Section: Introductionmentioning

confidence: 99%

Stereochemical analysis of β‐keto sulfoxides by circular dichroism

et al. 2017

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Three β-keto sulfoxides (1-3) were synthesized in enantiopure form and investigated by means of circular dichroism (CD) spectroscopy, both in electronic and vibrational range (ECD, VCD), in combination with quantum chemical calculations. For compound 2, the X-ray structure was available; thus, the ECD in the solid state was also considered to reveal the differences between the molecular species in both states. Despite the simplicity of all β-keto sulfoxides under investigation (29 atoms), reproducing even the major spectral VCD features failed for two compounds, making the use of VCD not ideal to assign their absolute configuration in a reliable way. We demonstrated, however, that the use of ECD spectroscopy, both in solution and solid state, can easily, unambiguously, and without any complication simulate all bands by applying the standard protocol for calculations. This study may stimulate the debate on the need of the use of two chiroptical methods simultaneously in the determination of absolute configurations.

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CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

Covington

Polavarapu

2017

Chirality

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The program CDSpecTech was developed to facilitate the analysis of chiroptical spectra, which include the following: vibrational circular dichroism (VCD) and corresponding vibrational absorption (VA) spectra; vibrational Raman optical activity (VROA) and corresponding vibrational Raman spectra; electronic circular dichroism (ECD) and corresponding electronic absorption (EA) spectra. In addition, the program allows for generating optical rotatory dispersion (ORD) as the Kramers-Kronig transform of ECD spectra. The simulation of theoretical spectra from transition strengths can be achieved using different bandshape profiles. The experimental and simulated theoretical spectra can be visually compared by displaying them together. A unique feature of CDSpecTech is performing spectral analysis using the ratio spectra; i.e., the dimensionless dissymmetry factor (DF) spectrum, which is the ratio of CD to absorption spectra, and the dimensionless circular intensity difference (CID) spectrum, which is the ratio of VROA to vibrational Raman spectra. The quantitative agreement between experimental and simulated theoretical spectra can also be assessed from the numerical similarity overlap between them. Two different similarity overlap methods are available. The program uses a graphical user interface which allows for ease of use and facilitates the analysis. All these features make CDSpecTech a valuable tool for the analysis of chiroptical spectra. The program is freely available on the World Wide Web.

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Absolute configurations of phytotoxic inuloxins B and C based on experimental and computational analysis of chiroptical properties

Cited by 28 publications

References 23 publications

Absolute configurations of chiral molecules with multiple stereogenic centers without prior knowledge of the relative configurations: A case study of inuloxin C

Absolute configurations of chiral molecules with multiple stereogenic centers without prior knowledge of the relative configurations: A case study of inuloxin C

Stereochemical analysis of β‐keto sulfoxides by circular dichroism

CDSpecTech: A single software suite for multiple chiroptical spectroscopic analyses

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