scholarly journals Beyond optical rotation: what's left is not always right in total synthesis

2018 ◽  
Vol 9 (2) ◽  
pp. 415-424 ◽  
Author(s):  
Leo A. Joyce ◽  
Christopher C. Nawrat ◽  
Edward C. Sherer ◽  
Mirlinda Biba ◽  
Andrew Brunskill ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Total Synthesis ◽  
Absolute Configuration ◽  
Optical Rotation ◽  
Circular Dichroism Spectroscopy ◽  
The Absolute ◽  
Frondosin B ◽  
Circular Dichroïsm

Longstanding debate on the absolute configuration of frondosin B was definitively solved using circular dichroism spectroscopy.

(-)-Strempeliopine, stereoselective total synthesis and the determination of absolute configuration

1986 ◽  
Vol 51 (8) ◽  
pp. 1731-1742 ◽  
Author(s):  
Josef Hájíček ◽  
Jan Trojánek
Keyword(s):  
Circular Dichroism ◽  
Total Synthesis ◽  
Absolute Configuration ◽  
Determination Of Absolute Configuration ◽  
Natural Base ◽  
The Absolute ◽  
Circular Dichroïsm

A synthesis of (±)-strempeliopine (II) is described, the key step of which is the stereoselective reductive rearrangement of 18-methylene-1,2-dehydroaspidospermidine (XI). The absolute configuration of the natural (-)-base II was determined as (2S, 7R, 20R, 21R) on the basis of its synthesis from (+)-18-methylenevincadifformine (XVII) the configuration of which was derived from a comparison of circular dichroism properties of bases with a β-anilinoacrylate chromophore. The biogenesis of the alkaloids of the schizozygane type is discussed.

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 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 Absolute configuration of the antimalarial erythro-mefloquine – vibrational circular dichroism and X-ray diffraction studies of mefloquine and its thiourea derivative

RSC Advances ◽  
2016 ◽  
Vol 6 (85) ◽  
pp. 81461-81465 ◽  
Author(s):  
M. Kohout ◽  
J. Vandenbussche ◽  
A. Roller ◽  
J. Tůma ◽  
J. Bogaerts ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Absolute Configuration ◽  
Circular Dichroism Spectroscopy ◽  
Vibrational Circular Dichroism ◽  
X Ray Diffraction ◽  
Thiourea Derivative ◽  
X Ray ◽  
The Absolute ◽  
Circular Dichroïsm

The long-standing discussion of the absolute configuration of erythro-mefloquine is revisited, showcasing the strength of a combination of experimental and calculated vibrational circular dichroism spectroscopy.

scholarly journals VCD Determination of the Absolute Configuration of Stypotriol

2009 ◽  
Vol 4 (8) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Marcelo A. Muñoz ◽  
Carlos Areche ◽  
Aurelio San-Martín ◽  
Juana Rovirosa ◽  
Pedro Joseph-Nathan
Keyword(s):  
Circular Dichroism ◽  
Natural Product ◽  
Absolute Configuration ◽  
Circular Dichroism Spectroscopy ◽  
Vibrational Circular Dichroism ◽  
Stypopodium Zonale ◽  
The Absolute ◽  
Circular Dichroïsm

The absolute configuration of the pentacyclic ichthyotoxin stypotriol, a constituent of Stypopodium zonale, was deduced to be 3S,5R,8R,9R,10S,13S,14S-(-)-1 by vibrational circular dichroism spectroscopy of the derived triacetate 2 in comparison to DFT B3LYP/DGDZVP calculations. Compound 2, C33H46O7 having 300 electrons, is the largest natural product successfully studied by VCD to date.

Flavanone glucuronides from the leaves of Garcinia prainiana

2011 ◽  
Vol 89 (4) ◽  
pp. 461-464 ◽  
Author(s):  
Saranyoo Klaiklay ◽  
Yaowapa Sukpondma ◽  
Vatcharin Rukachaisirikul ◽  
Nongporn Hutadilok-Towatana ◽  
Kanokphorn Chareonrat
Keyword(s):  
Antioxidant Activity ◽  
Circular Dichroism ◽  
Absolute Configuration ◽  
Circular Dichroism Spectroscopy ◽  
Spectroscopic Methods ◽  
Phytochemical Investigation ◽  
The Absolute ◽  
Circular Dichroïsm

Phytochemical investigation of Garcinia prainiana ’s leaves led to the isolation of prainianonide (1), a new flavanone glucuronide, together with six known compounds: (2S)-eriodictyol 7-O-β-d-glucuronide (2), naringenin 7-O-β-d-glucuronide (3), (–)-GB-1a (4), (+)-morelloflavone (5), amenthoflavone (6), and friedelin (7). Their structures were elucidated by spectroscopic methods. The absolute configuration of 1 was determined by circular dichroism spectroscopy. Compounds 4 and 5 showed significant antioxidant activity.

Sign in / Sign up

Export Citation Format

Share Document