title: Structure and absolute configuration of hydroxy-bis-dihydrofarinosin from Encelia farinosa.
abstract: The structure of the dimeric eudesmanolide hydroxy-bis-dihydrofarinosin (1) from Encelia farinosa followed after contrasting their1H and13C 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.
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Mexico City, 04510, Mexico.
authors.forename: Alfredo R
authors.initials: AR
authors.lastname: Ortega
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Mexico City, 04510, Mexico.
authors.forename: Naytzé
authors.initials: N
authors.lastname: Ortiz-Pastrana
authors.affiliation: Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Mexico City, 04510, Mexico.
authors.forename: Leovigildo
authors.initials: L
authors.lastname: Quijano
authors.affiliation: Centro de Nanociencias y Micro y Nanotecnologías, Instituto Politécnico Nacional, Mexico City, 07738, Mexico.
authors.forename: Elvia
authors.initials: E
authors.lastname: Becerra-Martínez
authors.affiliation: Departamento de Ingeniería Eléctrica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, 07000, Mexico.
authors.forename: José O
authors.initials: JO
authors.lastname: Olmedo-Aguirre
authors.affiliation: Departamento de Química, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado 14-740, México City, 07000, Mexico.
authors.forename: Pedro
authors.initials: P
authors.lastname: Joseph-Nathan
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000737:chemistry; D019659:Asteraceae / Q000737:chemistry*; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D006575:Heterocyclic Compounds, 3-Ring; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012717:Sesquiterpenes / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D006575:Heterocyclic Compounds, 3-Ring; D012717:Sesquiterpenes; C476916:eudesmanolide; C000626860:hydroxy-bis-dihydrofarinosin; C093533:encelin; D015107:4-Butyrolactone
keywords: 750 1H NMR; dimeric eudesmanolides; farinosin; hydroxy-bis-dihydroencelin, X-ray diffraction; hydroxy-bis-dihydrofarinosin, encelin