Stereochemical assignment of fusiccocadiene from NMR shielding constants and vibrational circular dichroism spectroscopy

Merten, Christian; Dirkmann, Michael; Schulz, Frank

doi:10.1002/chir.22708

Cited by 9 publications

(7 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The relative stereochemistry of FCdiene 81 (Figure 22), isolated from fermentation of Saccharomyces cerevisiae , was confirmed by comparison of experimental and predicted 13 C–NMR chemical shifts and the AC followed from its IR and VCD spectra as (6 S ,7 S ,11 R )-fusicocca-2,10(14)-diene ( 81 ). 56…”

Section: Resultsmentioning

confidence: 99%

“…55 The relative stereochemistry of FCdiene 81 ( Figure 22), isolated from fermentation of Saccharomyces cerevisiae, was confirmed by comparison of experimental and predicted 13 C-NMR chemical shifts and the AC followed from its IR and VCD spectra as (6S,7S,11R)-fusicocca-2,10(14)-diene (81). 56 The stereochemistry of a new isopimarane-type diterpenoid, isolated from Callicarpa macrophylla Vahl, was studied by ECD and VCD with the aid of TDDFT calculations confirming the AC as (4S,5S,9S,10S,13S,14S)−14α-hydroxy-7,15isopimaradien-18-oic acid (82) ( Figure 22). 57 The known mixture of horminone (83) and taxoquinone (84) ( Figure 23) was isolated from the aerial parts of Salvia concolor Lamb.…”

Section: Monoterpenoids the Formulas Of The 28 Monoterpenoids Includmentioning

confidence: 99%

See 1 more Smart Citation

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Río

Joseph‐Nathan

2021

Natural Product Communications

View full text Add to dashboard Cite

Although demonstrated in 1975, vibrational circular dichroism (VCD) finally started to popularize during this century as a reliable tool to determine the absolute configuration (AC) of organic molecules. This research field continues to be a very dynamic one, in particular for the study of natural products which are a unlimited source of chiral molecules. It therefore turns of interest to summarize the accomplishments published in recent years and to comment on some eventual difficulties that emerged in rare cases to complete the AC determination task. Therefore the aim of this review is to update VCD results for the AC assignment of natural products published from 2015 to 2019, a period in which VCD was reported in some 126 publications involving almost 300 molecules. They are organized according the type of studied metabolite allowing an easily search. The molecules correspond to 28 monoterpenes concerning 17 papers, to 42 sesquiterpenes in 14 papers, to 51 diterpenes in 19 publications, to 5 other terpenoids in three papers, to 48 aromatic molecules in 15 reports, to 20 polyketides in 10 publications, to 27 miscellaneous formulas also in 10 papers, and to 76 nitrogen containing compounds, which include alkaloids and their synthetic analogs, in 38 articles. The landscape of reviewed molecules is quite wide as it goes from simple monoterpenes, like borneol or camphor, to very relevant biological molecules like the alkaloid cocaine or tadalafil samples to distinguish genuine and counterfeit Cialis®. In addition, 5 natural products and a simple derivative published outside the reviewed period, were used to illustrate some aspects of density functional theory calculations.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Monoterpenoids the Formulas Of The 28 Monoterpenoids Includmentioning

confidence: 99%

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Río

Joseph‐Nathan

2021

Natural Product Communications

View full text Add to dashboard Cite

show abstract

“…The GIAO NMR shift calculation is integral part of a VCD intensity calculation, and thus these values are usually available after the VCD spectral analysis. Combining an IR/VCD spectroscopic analysis can thus easily be supplemented by the DP4 probability [ 26 ]. In the present case, however, the NMR and vibrational spectra were recorded in different solvents, so that the geometries of 1 used to simulate the IR and VCD spectra were subjected to another cycle of optimization and GIAO NMR shift calculation employing the IEFPCM of benzene.…”

Section: Resultsmentioning

confidence: 99%

Bifurcatriol, a New Antiprotozoal Acyclic Diterpene from the Brown Alga Bifurcaria bifurcata

et al. 2017

Self Cite

View full text Add to dashboard Cite

Linear diterpenes that are commonly found in brown algae are of high chemotaxonomic and ecological importance. This study reports bifurcatriol (1), a new linear diterpene featuring two stereogenic centers isolated from the Irish brown alga Bifurcaria bifurcata. The gross structure of this new natural product was elucidated based on its spectroscopic data (IR, 1D and 2D-NMR, HRMS). Its absolute configuration was identified by experimental and computational vibrational circular dichroism (VCD) spectroscopy, combined with the calculation of 13C-NMR chemical shielding constants. Bifurcatriol (1) was tested for in vitro antiprotozoal activity towards a small panel of parasites (Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, and Leishmania donovani) and cytotoxicity against mammalian primary cells. The highest activity was exerted against the malaria parasite P. falciparum (IC50 value 0.65 μg/mL) with low cytotoxicity (IC50 value 56.6 μg/mL). To our knowledge, this is the first successful application of VCD and DP4 probability analysis of the calculated 13C-NMR chemical shifts for the simultaneous assignment of the absolute configuration of multiple stereogenic centers in a long-chain acyclic natural product.

show abstract

“…For the two methods, the common medium is the liquid or solution phase. They are powerful in determining the absolute configurations (ACs), ,,− conformation of molecules, − and intermolecular interactions in solutions. − …”

Section: Introductionmentioning

confidence: 99%

Chiral Thiophene Sulfonamide—A Challenge for VOA Calculations

et al. 2017

View full text Add to dashboard Cite

Two enantiomers of 2-methyl-N-(1-thien-2-ylethyl)propane-2-sulfonamide (TSA) were synthesized, and their VCD, ROA, IR, and Raman spectra were registered. The solved (S)-TSA X-ray structure shows a disorder connected to the presence of two TSA conformers differing by a slight rotation of the thiophene ring. Two molecules in the unit cell of the monoclinic P2 crystal form a net of NH···OS and C*H···OS hydrogen bonds. Out of a series of computational levels tested to interpret the spectra, the B3LYP functional combined with the def2TZVP basis set satisfactorily reproduces the experimental VCD and ROA spectra. To simulate the VCD spectra of TSA enantiomers in KBr pellets, dimers and tetramers, with two different positions of the thiophene ring, were considered. The VCD spectra measured in CDCl are completely different from those taken in KBr due to the conformational freedom of TSA in chloroform. Seven TSA conformers fall into two groups of opposite configurations at the pyramidal N atom forming the additional stereogenic center. However, the barriers between conformers in each group are lower than the energy of thermal motions at 300 K. Thus, all conformers, but the most stable in each group, are likely to be metastable states. The calculated IR, VCD, Raman, and ROA spectra of the conformers depend not only on the type of stereogenic N atom but also on the thiophene ring rotation. Yet, they are likely to coexist because of low barriers between them. Three approaches were tested to reproduce the chiroptical spectra in solution using PCM and hybrid solvation models. As a consequence, it was found that a model in which all conformers contribute to the spectra with equal population factors seems to best reproduce the experimental data. Such a result suggests that in a dissolved state in 300 K TSA occurs in a very shallow potential well and all of its conformers coexist.

show abstract

Stereochemical assignment of fusiccocadiene from NMR shielding constants and vibrational circular dichroism spectroscopy

Cited by 9 publications

References 26 publications

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Vibrational Circular Dichroism Absolute Configuration of Natural Products From 2015 to 2019

Bifurcatriol, a New Antiprotozoal Acyclic Diterpene from the Brown Alga Bifurcaria bifurcata

Chiral Thiophene Sulfonamide—A Challenge for VOA Calculations

Contact Info

Product

Resources

About