The crystal structure of eudesma-4(15),7(11)-dien-8α, 12-olide: a sesquiterpene lactone fromTrattinickia rhoifolia Willd

The title compound, formula C₁₅H₂₀O₂, is orthorhombic, P2₁2₁2₁ witha=8.747(2),b=12.025(3),c=12.554(3)Å,Z=4, andD _m =1.32(2)g/ml. The structural analysis shows that the compound corresponds to eudesma-4(15),7(11)-dien-8,12-olide, a sesquiterpene lactone previously isolated fromAster umbellatus but whose crystal structure was unknown.     

Structural determination of three new eudesmanolides from Inula helenium

Ten sesquiterpenens were isolated from Inula helenium. Among them, three eudesmanolides: 15-hydroxy-11betaH-eudesm-4-en-8beta,12-olide (1), 3alpha-hydroxy-11betaH-eudesm-5-en-8beta,12-olide (2) and 2beta, 11alpha-dihydroxy-eudesm-5-en-8beta,12-olide (3) are new compounds. Their chemical structures were determined by spectral methods including 2D NMR.     

Eudesmanolides from <Emphasis Type="Italic">Artemisia lehmanniana</Emphasis>. Crystal and molecular structures of 1α-acetoxy-4α-hydroxy-5,7α,6,11β(H)-eudesm-2,3-en-,12-olide and 1α-acetoxy-3α-hydroxy-5,7α,6,11β(H)-eudesm-4,15-en-6,12-olide

Two eudesmane sesquiterpene lactones of composition C₁₇H₂₄O₅ were isolated from the aerial part of Artemisia lehmanniana Bunge. X-ray structure analysis established their crystal and molecular structures.Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 458–460, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Spectral Data of Chemical Modification Products of Costunolide

Epoxidation of costunolide (1) yielded parthenolide (3), 1, 10-epoxycostunolide (4), and the cyclization products of 4, santamarin (5), reynosin (6), magnolialide (7) and a 1, 4-epoxyeudesmanolide (8). Reduction of santamarin (5) with sodium borohydride afforded 11, 13-dihydrosantamarin (9) and an eudesmen-triol (10). Reduction of reynosin (6) provided 11, 13-dihydroreynosin (11) and the two eudesman-triols 12 and 13. The structures of the new compounds were elucidated by ID and 2D ¹H and ¹³C NMR spectral methods.     

Structure and absolute configuration of hydroxy‐bis‐dihydrofarinosin from Encelia farinosa

The structure of the dimeric eudesmanolide hydroxy‐bis‐dihydrofarinosin ( 1 ) from Encelia farinosa followed after contrasting their ¹H and ¹³C 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.     

Isolation and structures of eudesmanolides from Tanacetum cadmeum ssp. cadmeum

Eight sesquiterpene lactones, two coumarins, and two flavonoid derivatives were isolated from Tanacetum cadmeum (Boiss.) Heywood ssp. cadmeum. All compounds have been found previously in other plant species. The crystal structures of artesin and taurin are reported. Crystals of artesin (C₁₅H₂₂O₃) belong to the monoclinic space group P2₁: a = 8.300(1), b = 6.304(1), c = 13.118(2) Å, = 101.836(3)°, V = 671.8(2), Z = 2, R ₁ = 0.0291. Crystals of taurin belong to the monoclinic space group P2₁: a = 5.722(1), b = 8.279(2), c = 14.503(3) Å, = 90.025(1)° , V = 687.0(3), Z = 2, R ₁ = 0.0493. An investigation of the space group indicated a monoclinic system rather than orthorhombic.     

MODELLING TRANSANNULAR CYCLIZATION OF 1(10)E,4E-GERMACRANOLIDE COSTUNOLIDE INTO EUDESMANE DERIVATIVES

Semi-empirical quantum-chemical methods were used to model transannular cyclization of 1(10)E,4E-germacranolide costunolide into eudesmanolides. The conformational states favorable for the transformation and the energy barriers were calculated.