Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Pauli, Guido F.; Niemitz, Matthias; Bisson, Jonathan; Lodewyk, Michael W.; Soldi, Cristian; Shaw, Jared T.; Tantillo, Dean J.; Saya, Jordy M.; Vos, Klaas; Kleinnijenhuis, Roel A.; Hiemstra, Henk; Chen, Shao-Nong; McAlpine, James B.; Lankin, David C.; Friesen, J. Brent

doi:10.1021/acs.joc.5b02456

Cited by 37 publications

(41 citation statements)

References 39 publications

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“…6 Again, the authors provided the original FID, from which we could demonstrate the rapid dereplication of the isolated natural product vs. the synthesized compound. The resulting report 1 demonstrates the power of shared HNMR FIDs and adequate tabular description for the promotion of accurate structural elucidation and reliable dereplication.…”

Section: B Fids Foster Reproducibility and Integritymentioning

confidence: 85%

“…Moreover, such data preserves all chemical information that a given experiment encodes, the decoding of which depends on both the skills of the interpreters and the capability of available methodology. This in particular applies to the mother of all NMR experiments, the 1D 1 H NMR (HNMR) spectrum: 1 with the caveat of proton- or J -deficient molecules, HNMR spectra exhibit a very high information content. In fact, when mined appropriately, they encode virtually all the structural information pertaining to a natural product.…”

Section: A Fids Are Hidden Treasuresmentioning

confidence: 99%

“…In addition, the spectrum was analyzed with quantum mechanics (QM) based software to reveal the entire J -coupling information contained in complex signals. 1, 2 In the course of this work, the total synthesis of aquatolide was published. 6 Again, the authors provided the original FID, from which we could demonstrate the rapid dereplication of the isolated natural product vs. the synthesized compound.…”

Section: B Fids Foster Reproducibility and Integritymentioning

confidence: 99%

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Dissemination of original NMR data enhances reproducibility and integrity in chemical research

et al. 2016

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The notion of data transparency is gaining a strong awareness among the scientific community. The availability of raw data is actually regarded as a fundamental way to advance science by promoting both integrity and reproducibility of research outcomes. Particularly, in the field of natural product and chemical research, NMR spectroscopy is a fundamental tool for structural elucidation and quantification (qNMR). As such, the accessibility of original NMR data, i.e., Free Induction Decays (FIDs), fosters transparency in chemical research and optimizes both peer review and reproducibility of reports by offering the fundamental tools to perform efficient structural verification. Although original NMR data are known to contain a wealth of information, they are rarely accessible along with published data. This Viewpoint discusses the relevance of the availability of orginal NMR data as part of Good Research Practices not only to promote structural correctness, but also to enhance traceability and reproducibility of both chemical and biological results.

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Section: B Fids Foster Reproducibility and Integritymentioning

confidence: 85%

Section: A Fids Are Hidden Treasuresmentioning

confidence: 99%

Section: B Fids Foster Reproducibility and Integritymentioning

confidence: 99%

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Dissemination of original NMR data enhances reproducibility and integrity in chemical research

et al. 2016

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“…8a, 14 We hope that this study, which underscores the potential of computational methods as a key tool for assessing the structure of complex organic molecules, will provide helpful guidance to further synthetic work needed to ultimately unravel the mystery that surrounds rubriflordilactone B.…”

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confidence: 90%

Computational Chemistry Driven Solution to Rubriflordilactone B

2016

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The structure of rubriflordilactone B (2) was determined by X-ray crystallography. However, the NMR data of the synthetic sample did not match those reported for 2. It was then suggested that the original sample contained an additional isomer of different solubility, pseudorubriflordilactone B (3), whose structure remained unknown. From theoretical calculations, reexamination of the NMR data, and biogenetic considerations, it is proposed that 3 should be the 16S,17R isomer of 2.T he Schisandraceae, comprising about 50 species of medicinally and economically relevant climbing plants belonging to the genera Katsura and Schisandra, are chiefly distributed in North America and the Southeast of Asia. Their phytochemistry has been recently reviewed, covering around 400 triterpenoids identified up to 2014. 1In 2006, Sun and co-workers reported the isolation of two highly unsaturated rearranged bisnortriterpenoids from Schisandra rubrif lora, designated as rubriflordilactones A (1) and B (2), Figure 1. These structures, featuring unique polysubstituted central aromatic rings, were respectively assigned to the novel compounds after detailed NMR spectroscopic analyses. Further, both proposed structures were confirmed by X-ray crystallography. 2Both natural products exhibited anti-HIV activity; the EC 50 of 2 against viral replication in HIV-1 IIIB -infected C8166 cells was 9.75 μg/mL. The latter also displayed low cytotoxicity against K562 cells.Two total syntheses of compound 1 have been reported so far, 3 whereas synthetic studies of the CDE, 5-epi-ABCDE, and DEFG ring fragments of 2 4 were crowned by its recent total synthesis, disclosed by Li and co-workers.5 Surprisingly, however, although the X-ray analysis of the synthesized structure 2 clearly confirmed its identity, its 1 H and 13 C NMR spectra were unlike those of the authentic product.Since the differences could not be attributed to solvent, temperature, concentration, or other usual factors, the authors hypothesized that the original sample of "rubriflordilactone B" may have contained two compounds with different solubility. The minor one crystallized, affording the reported X-ray structure which agrees with 2, whereas the major component, probably an isomer of 2, which was termed "pseudorubriflordilactone B", could be responsible for the observed bioactivities and published specific rotation and NMR spectroscopic data.Taking into account our interest in natural product characterization 6 using quantum chemical calculations of NMR shifts 7 and considering the remote possibility of unveiling the structure of pseudorubriflordilactone B (3) by reisolation of the natural product, we decided to examine the problem from a theoretical viewpoint. This approach has been employed in recent and resonant cases of structural misassignments, 8a−d providing useful insight in subtle issues beyond the limits of Xray methods as well. As most of the 13 C chemical shifts of isolated 3 were in close agreement with those found for synthetic compound 2 (except for δC15, vi...

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“…In 2016, Tantillo and co-workers 78 pointed out the importance of retrieving free induction decay (FID) data from NMR analyses in order to support reprocessing and reanalysis of published data and they introduced quantum interaction and linkage tables (QuILTs) for a more intuitive visualization of 1D J-coupling relationships, NOESY correlations, and heteronuclear experiments. The structure 153 proposed by Tantillo and co-workers 77 was eventually prepared by Hiemstra and co-workers 77 featuring an intramolecular [2 + 2]-photocycloaddition between an allene and an α,β-unsaturated δ-lactone as the key step to construct its tricyclic core (Scheme 20).…”

Section: Aquatolidementioning

confidence: 99%

Computer-Guided Total Synthesis of Natural Products. Recent Examples and Future Perspectives

Della‐Felice¹,

Pilli²,

Sarotti³

2018

J. Braz. Chem. Soc.

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Quantum chemical calculations of nuclear magnetic resonance (NMR) shifts and coupling constants have been extensively employed in recent years mainly to facilitate structural elucidation of organic molecules. When the results of such calculations are used to determine the most likely structure of a natural product in advance, guiding the subsequent synthetic work, the term "computer-guided synthesis" could be coined. This review article describes the most relevant examples from recent literature, highlighting the scope and limitations of this merged computational/experimental approach as well.

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Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Cited by 37 publications

References 39 publications

Dissemination of original NMR data enhances reproducibility and integrity in chemical research

Dissemination of original NMR data enhances reproducibility and integrity in chemical research

Computational Chemistry Driven Solution to Rubriflordilactone B

Computer-Guided Total Synthesis of Natural Products. Recent Examples and Future Perspectives

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