2026-05-05T19:36:54Zhttps://uvadoc.uva.es/oai/request

oai:uvadoc.uva.es:10324/478302022-01-06T22:16:12Zcom_10324_28542com_10324_952com_10324_894col_10324_28543

Molecular rotation spectrum of tetracyclic quinolizidines: Observation of trans-Matrine and the elusive cis-Matrine Juanes San José, Marcos Saragi, Rizalina Tama Enríquez Giraudo, María Lourdes Jaraíz Maldonado, Martín Lesarri Gómez, Alberto Eugenio Sensors Sensores Electromagnetic radiation Radiación electromagnética Organic compounds Compuestos orgánicos Molecular structures Estructuras moleculares Producción Científica We characterized the bis-quinolizidine tetracyclic alkaloid (5S, 6S, 7R, 11R)-matrine in a supersonic jet expansion, using chirped-pulsed broadband microwave spectroscopy. Previous crystal diffraction analyses suggested 16 diastereoisomers associated with matrine’s four carbon stereocenters but were inconclusive whether the lactamic nitrogen atom would additionally produce separated trans-/cis- diastereoisomers or if both species may interconvert through low potential barriers. Our experiment simultaneously detected trans- and cis-matrine through their rotational spectrum, confirming the possibility of conformational rearrangement in matrine alkaloids. The two matrine conformers mainly differ in the envelope or half-chair lactamic ring, as evidenced by the experimental rotational and nuclear quadrupole coupling parameters. Molecular orbital calculations with ab initio (MP2) and density functional methods (B3LYP-D3(BJ) and MN15) were tested against the experiment, additionally offering an estimation of the cis-/trans- barrier of 24.9–26.9 kJ mol–1. The experiment illustrates the structural potential of chirped-pulsed broadband microwave spectroscopy for high-resolution rotational studies of biomolecules in the range of 20–40 atoms. Ministerio de Ciencia e Innovación - Fondo Europeo de Desarrollo Regional (grant PGC2018-098561-B-C22) Junta de Castilla y León (grant VA056G18) 2021-07-30T08:21:58Z 2021-07-30T08:21:58Z 2021 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion The Journal of Organic Chemistry, 2021, vol. 86, n. 2. p. 1861–1867 1520-6904 https://uvadoc.uva.es/handle/10324/47830 10.1021/acs.joc.0c02689 eng https://pubs.acs.org/doi/10.1021/acs.joc.0c02689 Attribution-NonCommercial-NoDerivatives 4.0 Internacional info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ © 2021 ACS Publications application/pdf ACS Publications https://uvadoc.uva.es/bitstream/10324/47830/2/Molecular-rotation-spectrum.pdf.jpg Hispana TEXT http://creativecommons.org/licenses/by-nc-nd/4.0/ UVaDOC. Repositorio Documental de la Universidad de Valladolid https://uvadoc.uva.es/handle/10324/47830