Determining the absolute configuration of benzopyrenomycin by optical rotation, electronic circular dichroism, and population analysis of different conformations via DFT methods and experiments

Tetrahedron ◽  
2013 ◽  
Vol 69 (14) ◽  
pp. 3067-3074 ◽  
Author(s):  
Qing-Ming Li ◽  
Jie Ren ◽  
Bei-Dou Zhou ◽  
Bing Bai ◽  
Xin-Chun Liu ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Population Analysis ◽  
Dft Methods ◽  
Electronic Circular Dichroism ◽  
The Absolute ◽  
Circular Dichroïsm

scholarly journals Absolute Configuration Sensing of Chiral Aryl- and Aryloxy-Propionic Acids by Biphenyl Chiroptical Probes

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 154
Author(s):  
Stefania Vergura ◽  
Stefano Orlando ◽  
Patrizia Scafato ◽  
Sandra Belviso ◽  
Stefano Superchi
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Environmental Pollutants ◽  
Red Shift ◽  
Electronic Circular Dichroism ◽  
Configuration Assignment ◽  
Clear Sign ◽  
The Absolute ◽  
Circular Dichroïsm

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, the 4,4′-biphenyl substitution gives rise to a red shift of the diagnostic electronic circular dichroism signal of the biphenyl A band employed for the configuration assignment, removing its overlap with other interfering dichroic bands and allowing its clear sign identification. The largest A band red shift, and thus the most reliable results, are obtained by employing as a probe the 4,4′-dinitro substituted biphenylazepine 3c. The method was applied to the absolute configuration assignment of 2-arylpropionic acids ibuprofen (1a), naproxen (1b), ketoprofen (1c) and flurbiprofen (1d), as well as to the 2-aryloxypropionic acids 2-phenoxypropionic acid (2a) and 2-naphthoxypropionic acid (2b). This approach, allowing us to reveal the sample’s absolute configuration by simple optical rotation measurements, is potentially applicable to online analyses of both the enantiomeric composition and absolute configuration of these chiral pollutants.

scholarly journals α-Photooxygenation of chiral aldehydes with singlet oxygen

2019 ◽  
Vol 15 ◽  
pp. 2076-2084 ◽  
Author(s):  
Dominika J Walaszek ◽  
Magdalena Jawiczuk ◽  
Jakub Durka ◽  
Olga Drapała ◽  
Dorota Gryko
Keyword(s):  
Circular Dichroism ◽  
Singlet Oxygen ◽  
Absolute Configuration ◽  
Dft Methods ◽  
Catalyst Structure ◽  
Electronic Circular Dichroism ◽  
Silyl Ethers ◽  
Td Dft ◽  
The Absolute ◽  
Circular Dichroïsm

Organocatalytic α-oxygenation of chiral aldehydes with photochemically generated singlet oxygen allows synthesizing chiral 3-substituted 1,2-diols. Stereochemical results indicate that the reaction in the presence of diarylprolinol silyl ethers is highly diastereoselective and that the configuration of a newly created stereocenter at the α-position depends predominantly on the catalyst structure. The absolute configuration of chiral 1,2-diols has been unambiguously established based on electronic circular dichroism (ECD) and TD-DFT methods.

scholarly journals Absolute Configuration Determination by Quantum Mechanical Calculation of Chiroptical Spectra: Basics and Applications to Fungal Metabolites

2018 ◽  
Vol 25 (2) ◽  
pp. 287-320 ◽  
Author(s):  
Stefano Superchi ◽  
Patrizia Scafato ◽  
Marcin Gorecki ◽  
Gennaro Pescitelli
Keyword(s):  
Natural Products ◽  
Circular Dichroism ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Computational Approach ◽  
Quantum Mechanical ◽  
Fungal Metabolites ◽  
Common Technique ◽  
The Absolute ◽  
Circular Dichroïsm

Background: Quantum mechanical simulations of chiroptical properties, such as electronic circular dichroism (ECD), optical rotation (OR), and vibrational circular dichroism (VCD), have rapidly become very popular to assign the absolute configuration of novel natural products. Objective: We review the application of the ECD/OR/VCD computational methodology to chiral metabolites of fungal origin. First, we summarize the fundamentals of the three spectroscopies; then, we focus on the specific experimental and computational issues allied to the application of their calculations. Methods: We surveyed the entire literature describing the use of ECD/OR/VCD computations for fungal metabolites, and catalogued all papers according to the method employed and to the structural family of compounds. Then, we chose several examples to illustrate the use of the techniques and highlight the practical application of the computational approach. Results: Our literature survey demonstrates that the simulation of ECD/OR/VCD spectra is nowadays widespread and accessible also to non-experts, although a good computational practice is necessary to avoid wrong assignments. ECD is still the most common technique used in the context of fungal metabolites. OR and VCD may be profitably employed when the compound of interest lacks chromophoric groups. Our examples illustrate that the combination of two or more chiroptical methods is strongly advisable in some cases, especially in the presence of high conformational flexibility, where a single technique does not lead to a safe conclusion. Conclusion: The ECD/OR/VCD computational approach is a reliable and versatile method to assign the absolute configuration of fungal metabolites and related natural products.

scholarly journals Use of Circular Dichroism to Determine the Absolute Configuration of a Pimarane Diterpenoid from the Southern African Sclerocroton integerrimus (Euphorbiaceae)

2014 ◽  
Vol 9 (8) ◽  
pp. 1934578X1400900 ◽  
Author(s):  
Vuyelwa J. Tembu ◽  
Moses K. Langat ◽  
Neil R. Crouch ◽  
Dulcie A. Mulholland
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Spectroscopic Analysis ◽  
Stem Bark ◽  
Electronic Circular Dichroism ◽  
The Absolute ◽  
Circular Dichroïsm

From the stem bark and leaves of Sclerocroton integerrimus, eight compounds, including 17-hydroxy- ent-pimara-8(14),15-dien-3-one (1), were isolated. The structures of the compounds were determined on the basis of spectroscopic analysis. The absolute configuration of 17-hydroxy- ent-pimara-8(14),15-dien-3-one was confirmed from electronic circular dichroism studies.

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