Revisiting the structure of Heliannuol L: A computational approach |
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Authors: | Lucas H Martorano Jordana T Brito Ana Carolina F de Albuquerque Carlos Magno Rocha Ribeiro Rodolfo Goetze Fiorot José Walkimar de Mesquita Carneiro Fabio Luiz Paranhos Costa Alessandra L Valverde Fernando Martins dos Santos Junior |
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Institution: | 1. Department of Organic Chemistry, Chemistry Institute, Fluminense Federal University (UFF), Niterói, Brazil;2. Department of Inorganic Chemistry, Chemistry Institute, Fluminense Federal University (UFF), Niterói, Brazil;3. Chemistry Institute, Federal University of Jataí (UFJ), Jataí, Brazil |
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Abstract: | Recently, structural elucidation of natural products has undergone a revolution. The combined use of different modern spectroscopic methods has allowed obtaining a complete structural assignment of natural products using small amounts of sample. However, despite the extraordinary ongoing advances in spectroscopy, the mischaracterization of natural products has been and remains a recurrent problem, especially when the substance presents several stereogenic centers. The misinterpretation of nuclear magnetic resonance (NMR) data has resulted in frequent reports addressing structural reassignment. In this context, a great effort has been devoted to developing quantum chemical calculations that simulate NMR parameters accurately, allowing to achieve a more precise spectral interpretation. In this work, we employed a protocol for theoretical calculations of 1H NMR chemical shifts and coupling constants using density functional theory (DFT), followed by the application of the DP4+ method to revisit the structure of Heliannuol L, a member of the Heliannuol class, isolated from Helianthus annuus. Our results indicate that the originally proposed structure of Heliannuol L needs a stereochemical reassignment, placing the hydroxyl bonded to C10 in the opposite side of the methyl and hydroxyl groups bonded to C7 and C8, respectively. |
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Keywords: | DP4+ Heliannuol natural products reassignment |
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