Recent advances in the use of vibrational chiroptical spectroscopic methods for stereochemical characterization of natural products

The known antibiotic and cytotoxic compounds griseorhodin A (1) and griseorhodin C (2) were produced in solid culture by Streptomyces puniceus AB10, which was isolated from the leaf-cutter ant Acromyrmex rugosus rugosus. Their absolute configurations were unambiguously established as 6S,6aR,7S,8S and 6R,6aR,7S,8R, respectively, using vibrational circular dichroism (VCD) and density functional theory (DFT) calculations.

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“…VCD is a well-established and reliable method for stereochemical studies of natural molecules directly in solution-phase. 11 …”

Section: Introductionmentioning

confidence: 99%

Absolute configurations of griseorhodins A and C

Ortega

Batista

Melo

et al. 2017

Tetrahedron Letters

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“…of little populated conformers. [11][12][13] Furthermore, VCD spectroscopy has been shown to be a very powerful technique to study intermolecular interactions such as solutesolvent [14][15][16][17] or solute-solute [18][19][20][21][22] interactions as well as chirality transfer phenomena. Slight warming of the solid matrix also enables the diffusion controlled generation of larger molecular clusters.…”

Section: Introductionmentioning

confidence: 99%

Conformational distortion of α-phenylethyl amine in cryogenic matrices – a matrix isolation VCD study

Pollok

Merten

2016

Phys. Chem. Chem. Phys.

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The chiral amine α-phenylethyl amine (PEA) was isolated in cryogenic matrices and investigated using vibrational circular dichroism (VCD) and infrared spectroscopy. The potential energy surface (PES) of PEA features five different conformers connected by relatively low conformational transition states. Based on the IR spectra, it could be confirmed that all conformational energy barriers are passed at a deposition temperature of 20 K, and that only the global minimum conformation of PEA is populated in both argon and nitrogen matrices. However, differences in the calculated and experimental VCD spectra indicate deviations from the minimum structure by perturbation of the phenyl ring as well as of the amine orientation. The degree of the perturbation is found to also depend on the choice of the host gas, which shows the subtle influence of the environment on the conformational distortion of PEA.

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“…6,7 This approach has proved to be particularly useful in the case of natural products, an important source for drug discovery often exhibiting molecular flexibility, multiple functional groups, or chromophores. 8 To increase the confidence level of the stereochemical analysis, the use of different chiroptical techniques is postulated. 9-17 On the other hand, the determination of the absolute configuration of molecules with many stereogenic centers by chiroptical methods is still a challenge, and is rather limited to rigid molecules.…”

Section: Introductionmentioning

confidence: 99%

“…9-17 On the other hand, the determination of the absolute configuration of molecules with many stereogenic centers by chiroptical methods is still a challenge, and is rather limited to rigid molecules. 8,15, 18–21 In the case of diastereomers, there is no spectra mirror relationship as for enantiomers, and therefore, in order to unambiguously assign the absolute configuration, the compared experimental and calculated data have to be of very good quality. Nevertheless, successful attempts exist for the absolute configuration assignment of large and flexible molecules.…”

Section: Introductionmentioning

confidence: 99%

Reassignment of the absolute configuration of plakinidone from the sponge consortium Plakortis halichondrioides–Xestospongia deweerdtae using a combination of synthesis and a chiroptical approach

Jiménez-Romero

Rode

Rodrı́guez

2016

Tetrahedron: Asymmetry

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Recent work by Wu et al. in connection with the first synthesis of the marine natural product plakinidone revealed that the most salient feature of its purported structure, a six-membered perlactone moiety, was in fact a five-membered lactone, i.e. a 3-methyl-4-hydroxy-2(5H)-furanone or tetronic acid ring. With the planar structure of plakinidone confidently revised, we undertook a new investigation to unambiguously establish its absolute configuration. Upon preparing two stable derivatives 1 and 5 from a sample of naturally occurring plakinidone extracted from the sponge association Plakortis halichondriodes–Xetospongia deweerdtae, the absolute configuration was assigned by synthesis and vibrational and electronic circular dichroism (VCD and ECD) measurements in combination with density functional theory calculations at the B3LYP/aug-cc-pVDZ/PCM(CH3CN) level of theory. Our combined efforts and the agreement between the experimental and calculated VCD/ECD spectra of 1 revealed that the absolute configuration of plakinidone was in fact (11S,17R) and not the formerly reported (11S,17S) diastereomer assigned by Wu et al.. Therefore, we propose that natural plakinidone is accurately represented by structure 12.

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Recent advances in the use of vibrational chiroptical spectroscopic methods for stereochemical characterization of natural products

Abstract: This review covers conformational and configurational assignments in natural product molecules using chiroptical spectroscopy reported over the last 15 years. Special attention is given to vibrational optical activity methods associated with quantum mechanical calculations.

Cited by 166 publications

References 189 publications

Absolute configurations of griseorhodins A and C

Absolute configurations of griseorhodins A and C

Conformational distortion of α-phenylethyl amine in cryogenic matrices – a matrix isolation VCD study

Reassignment of the absolute configuration of plakinidone from the sponge consortium Plakortis halichondrioides–Xestospongia deweerdtae using a combination of synthesis and a chiroptical approach

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