Absolute configuration reassignment of nectamazin A: Implications to related neolignans.

Autor: Batista ANL; Universidade Federal Fluminense, Instituto de Química, Outeiro de São João Batista s/n, Niterói, RJ 24020-141, Brazil., Santos CHT; Universidade Federal de Mato Grosso do Sul, Instituto de Química, Av. Senador Filinto Muller 1555, Campo Grande, MS 79074-460, Brazil., de Albuquerque ACF; Universidade Federal Fluminense, Instituto de Química, Outeiro de São João Batista s/n, Niterói, RJ 24020-141, Brazil., Santos FM Jr; Universidade Federal Fluminense, Instituto de Química, Outeiro de São João Batista s/n, Niterói, RJ 24020-141, Brazil., Garcez FR; Universidade Federal de Mato Grosso do Sul, Instituto de Química, Av. Senador Filinto Muller 1555, Campo Grande, MS 79074-460, Brazil. Electronic address: fernanda.garcez@ufms.br., Batista JM Jr; Universidade Federal de São Paulo, Instituto de Ciência e Tecnologia, Rua Talim 330, São José dos Campos, SP 12231-280, Brazil. Electronic address: batista.junior@unifesp.br.
Jazyk: angličtina
Zdroj: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy [Spectrochim Acta A Mol Biomol Spectrosc] 2024 Jan 05; Vol. 304, pp. 123283. Date of Electronic Publication: 2023 Aug 21.
DOI: 10.1016/j.saa.2023.123283
Abstrakt: The ability of nature to produce structurally complex molecules makes the determination of the absolute configuration of natural products a challenging task. Although extensive NMR analysis generally allows for the reliable assignment of relative configurations, the assignments of absolute stereochemistry are commonly performed by empirical comparisons of optical rotation (OR) and/or electronic circular dichroism (ECD) data obtained for related molecules. Such an approach, however, may lead to misassignments and consequent error propagations. Herein, we present the case of the bicyclo(3.2.1)octane neolignan named (+)-nectamazin A. This compound was first reported in 2009 from Nectandra amazonum Nees. (Lauraceae) and had its absolute configuration determined as 7R,8S,3'S,4'R,5'S by means of experimental ECD spectroscopy. Our chemical studies on Ocotea aciphylla (Lauraceae) led to the isolation of (+)-nectamazin A. The extensive analysis of OR, ECD, and vibrational CD data aided by quantum chemical calculations, however, indicated (+)-nectamazin A to have the 7S,8R,3'R,4'S,5'R absolute configuration, in conflict with the configuration reported in the literature. The cause of the original incorrect assignment of (+)-nectamazin A derives from the direct comparison of experimental OR and ECD data obtained for structurally related molecules with different chromophoric systems. As an alternative, VCD spectroscopy is presented as a more reliable and sensitive technique to stereochemical investigations of bicyclo(3.2.1)octane neolignans.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2023 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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