Year-end Sale % OFF 
Abstract
Marine organisms are an increasingly important source of novel metabolites, some of which have already inspired or become new drugs. In addition, many of these molecules show a high degree of novelty from a structural and/or pharmacological point of view. Structure determination is generally achieved by the use of a variety of spectroscopic methods, among which NMR (nuclear magnetic resonance) plays a major role and determination of the stereochemical relationships within every new molecule is generally the most challenging part in structural determination. In this communication, we have chosen okadaic acid as a model compound to perform a computational chemistry study to predict 1H and 13C NMR chemical shifts. The effect of two different solvents and conformation on the ability of DFT (density functional theory) calculations to predict the correct stereoisomer has been studied.
Highlights
Marine natural products have generated great interest within the scientific community due to their fascinating biological activities, as well as by their extraordinary molecular diversity that have made them challenging problems for structure elucidation [1,2]
Our aim in this study is to verify that quantum mechanics computational simulations provide valid support to the structural characterization of the important group of polyether marine toxins, of which complex structures are usually elucidated on the basis of NMR spectral data
We present a systematic investigation of structure assignment using different statistical tools such as correlation coefficient (R2), corrected mean absolute deviation (CMAD) [5] and DP4 probability [6]
Summary
Marine natural products have generated great interest within the scientific community due to their fascinating biological activities, as well as by their extraordinary molecular diversity that have made them challenging problems for structure elucidation [1,2]. Structure determination is mostly achieved by interpretation of MS (mass spectrometry) and NMR (nuclear magnetic resonance) data and stereochemical assignments are generally the most time consuming step within this procedure [3] This is true when one has the need to assign independent molecular segments containing remote stereogenic centers, though it can be done by the use of the 3JH,H and 2,3JC,H providing an adequate number of them can be measured [4]. As NMR chemical shifts are strongly affected by molecular conformation; geometry optimization is a crucial factor in an accurate computation of NMR chemical shifts Regarding this point, Goodman et al [15] have reported that, estimates of energy and isotropic shielding in solution by DFT methods can be reliably obtained by single-point calculations on the gas-phase of structures obtained from faster molecular mechanics conformational searches, circumventing the need for time consuming optimizations in solvent. Relatively few studies have considered the difference between results obtained with and without solvent models, but the general conclusion is that consideration of solvent generally leads to an improvement of the results [9,16]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
