Ortega AR, Ortiz-Pastrana N, Quijano L, Becerra-Martínez E, Olmedo-Aguirre JO, Joseph-Nathan P. Structure and absolute configuration of hydroxy-bis-dihydrofarinosin from Encelia farinosa.
MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017;
55:530-539. [PMID:
27859567 DOI:
10.1002/mrc.4554]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 11/11/2016] [Accepted: 11/15/2016] [Indexed: 06/06/2023]
Abstract
The structure of the dimeric eudesmanolide hydroxy-bis-dihydrofarinosin (1) from Encelia farinosa followed after contrasting their 1 H and 13 C NMR spectra with those of encelin (6), hydroxy-bis-dihydroencelin (3), and farinosin (4). Structure 1 was verified by single-crystal X-ray diffraction analysis, which further provided the stereochemistry of the hydroxy group at C-4. Comparison of the experimental vibrational circular dichroism spectrum of its derived diacetate 2 with that calculated by density functional theory provided the absolute configuration, which resulted the same as that of its biogenetic precursor 4. Evaluation of several chemical shift differences between the two eudesmanolide fragments of 1 and 3 allows also ascertaining the yet not reported absolute configuration of the C-4 stereogenic center of 3. Copyright © 2016 John Wiley & Sons, Ltd.
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