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Conference

Danish NMR

iNANO building, Aarhus University, Aarhus, Denmark

Poster Details

Evaluation of the Benefit and Informing Capability of 2D NMR Experiments for Structure Elucidation Using CASE Software

Dimitris Argyropoulos and Mikhail Elyashberg

Computer Assisted Structure Elucidation (CASE) has been around for more than 50 years [1,2]. It has experienced a significant boost after the introduction of routine 2D NMR experiments in the 1990’s, as the increased information content offered allowed much more complex problems to be addressed. The evolution of computers and the processing power of modern CPUs allowed CASE to be a tool of reference for resolving the unique and unprecedented structures of natural products [3]. Some common questions encountered when spectroscopists are introduced to CASE are regarding the minimum set of experiments required to solve a problem by CASE and what is the value and informing capability of advanced NMR experiments. Although the answers vary depending on the problem complexity, in this poster we will try to tackle both questions, by demonstrating a few cases.

We will look at three example structures to answer these questions more efficiently: 2-Ethylindanone, Spirodactylone [4] and a xanthone-class natural product [5-6]. In the first example, which is a very simple molecule, we will examine the benefits of basic NMR experiments and how they affect the calculation time. The second example is a challenging natural product, and we will examine the benefits and potential problems that are encountered when using modern experiments like LR-HSQMBC, in addition to the traditional HSQC and HMBC. Here, we will also study the influence of manually adjusting atom properties, such as hybridization and connection to heteroatoms. The final example serves for considering the inter-relation between HMBC and INADEQUATE when a CASE system is used.

Exact details of the type of spectra used, and the calculations performed will be shown, as well as comparative tables on the achieved improvements in performance.

References

  1. Elyashberg, M., Argyropoulos, D. (2019). NMR Based Computer Assisted Structure Elucidation (CASE) of Small Organic Molecules in Solution: Recent Advances. eMagRes, 8, 239–254.
  2. Elyashberg, M., Argyropoulos, D. (2021). Computer Assisted Structure Elucidation (CASE): Current and future perspectives. Mag. Reson. Chem., 59(7), 669–690.
  3. M.E. Elyashberg, A.J. Williams. (2015). Computer-based Structure Elucidation from Spectral Data (p. 454). Springer-Verlag Berlin, Heidelberg
  4. Kang, U., Caldwell, D., et al. (2019). Elucidation of Spirodactylone, a Polycyclic Alkaloid from the Sponge Dactylia sp., and Nonenzymatic Generation from the Co-metabolite Denigrin B. Org. Lett., 21(12), 4750–4753.
  5. Boudesocque-Delaye, L., Agostinho, D., et al. (2015). Antibacterial Polyketide Heterodimers from Pyrenacantha kaurabassana Tubers. J. Nat. Prod.,78(4), 597–603.
  6. Omolo, J. J., Maharaj, V. et al. (2012). Bioassay-Guided Investigation of the Tanzanian Plant Pyrenacantha kaurabassana for Potential Anti-HIV-Active Compounds. J. Nat. Prod., 75(10), 1712–1716.
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