Irregular linear sesquiterpene dilactones from Anthemis auriculata Boiss

Seven new irregular linear sesquiterpene lactones, epi-antheindurolide A (1), epi-antheindurolide A-5,6-oxide (2), 5-hydroxy-5,6-dihydro-6,13-dehydro-epi-antheinduro lide A (3), 5-hydroperoxy-5,6-dihydro-6,13-dehydro-epi-antheindurolide A (4), epi-antheindurolide B (5), 6-hydroxy-5,6-dihydro-4,5-dehydro-epi-antheindurolide A (6) and 6-hydroperoxy-5,6-dihydro-4,5-dehydro-epi-antheindurolide A (7), were isolated from the flowers of Anthemis auriculata Bioss. Their structures were established by spectroscopic techniques. The discussed compounds were found to be stereoisomers of recently reported lactones for A. arvensis.     

A novel sesquiterpene lactone from vernonia erinacea

A new glaucolide containing a non-enolisable β-diketone on the ten membered ring was isolated. Acid catalysed cyclisation and dehydration yielded the hirsutinolide (furan-type germacranolide) structure. Degradative hydrogenation yielded a series of compounds which aided structure determination.     

Dendocarbin A: a sesquiterpene lactone from Drimys winteri

The natural compound dendocarbin A, C₁₅H₂₂O₃, is a sesquiterpene lactone isolated for the first time from Drimys winteri for var chilensis. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ and its X‐ray crystal structure confirmed the S/R character of the chiral centres at C‐5/C‐10 and C‐9/C‐11, respectively. The α‐OH group at C‐11 was found to be involved in intermolecular hydrogen bonding, defining chains along the <100> 2₁ screw axis.     

Biosynthesis of anthecotuloide,an irregular sesquiterpene lactone from Anthemis cotula L. (Asteraceae) via a non-farnesyl diphosphate route

Retrobiosynthetic analysis of the allergenic sesquiterpene lactone, anthecotuloide, suggested that this natural product could be formed either by head to head condensation of geranyl diphosphate with dimethylallyl diphosphate, or from farnesyl diphosphate (FPP), the accepted regular sesquiterpene precursor via the rearrangement of a germacranolide precursor. Isotopic labelling of anthecotuloide has now been achieved by feeding [1-(13)C]-glucose, [U-13C6]-glucose and [6,6-(2)H2]-glucose to aseptically grown plantlets of Anthemis cotula(family Asteraceae). Analysis of labelling patterns and absolute 13C abundances using quantitative 13C NMR spectroscopy showed that the isoprene building blocks of this sesquiterpene are formed exclusively via the MEP terpene biosynthetic pathway. This was supported by results from an experiment using [U-13C6]-glucose. A deuterium labelling experiment using [6,6-(2)H2]-glucose supported the original proposal and showed that anthecotuloide is formed from a non FPP precursor. Isotope ratio mass spectrometry suggested that there were two pathways for sesquiterpene biosynthesis in A. cotula.     

Igalan, a new sesquiterpene lactone from Inula grandis

Conclusions A new sesquiterpene lactone C₁₅H₂₀O₂ with mp 79–79.5°C, [] _D ²⁰ +105° (chloroform) has been isolated from the roots ofInula grandis Schrenk., and we have called it igalan. On the basis of chemical and spectral characteristics, it has been established that its most probable structure is eleman-8,11-olide.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 508–512, September–October, 1970.     

The structure of a sesquiterpene lactone from Artemisia fragrans

Summary From the epigeal part ofArtemisia fragrans Willd. a new sesquiterpene lactone C₁₅H₂₀O₄ has been isolated which has been called alkhanin.It has been shown that alkhanin has the structure (I).V. L. Komarov Institute of Botany, Academy of Sciences of the Azerbaidzhan SSR, Baku. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 75–77, January–February, 1978.     

Igalan,a new sesquiterpene lactone from Inula grandis

Chemistry of Natural Compounds - A new sesquiterpene lactone C15H20O2 with mp 79–79.5°C, [α] D 20 +105° (chloroform) has been isolated from the roots ofInula grandis Schrenk.,...     

Helivypolide G. A novel dimeric bioactive sesquiterpene lactone

In the course of our ongoing research for new allelochemicals from Helianthus annuus, a novel dimeric bioactive sesquiterpene lactone, helivypolide G has been isolated and characterized from the medium polar active fractions of the leaves of cultivar variety Stella. The monomers are connected through carbons C-15 of each unit and an oxygen bridge, forming an enolic oxane ring.     

A new sesquiterpene lactone from Bombax malabaricum

A new sesquiterpene lactone, 5-isopropyl-3-methyl-2,4,7-trimethoxy-8,1-naphthalene carbolactone (1) together with a known naphthoquinone, 8-formyl-7-hydroxy-5-isopropyl-2-methoxy-3-methyl-1,4-naphthoquinone (2) were isolated from the root bark of Bombax malabaricum. The structures of these two compounds were established by extensive one- and two-dimensional (1D- and 2D)-NMR spectral studies.     

A novel antileukemic sesquiterpene lactone. Synthesis of racemic eriolanin

The synthesis of dl-eriolanin 1, highly oxygenated 1,10-seco-eudesmanolide isolated from the chloroform extracts of Eriophyllum lanatum Forbes (Compositae), is reported.     

The formation of novel 1,3-dioxolanes: atypical Baylis-Hillman reaction of a sesquiterpene lactone parthenin

The Baylis-Hillman reaction of a sesquiterpene lactone parthenin with various aldehydes gave unexpected products containing a 1,3-dioxolane moiety. Both small aliphatic and aromatic aldehydes produced 1,3-dioxolanes, whereas higher aliphatic aldehydes produced normal Baylis-Hillman products.     

Naupliolide, a sesquiterpene lactone with a novel tetracyclic skeleton from Nauplius graveolens subsp. odorus

The aerial parts of Nauplius graveolens subsp. odorus (Schousb) Wikl. afforded a novel sesquiterpene lactone (1) named naupliolide together with the known 6,7,9,10-tetradehydroasteriscanolide 2 and asteriscunolides A-D 3a-d. The structure of compound 1 corresponds to a novel skeleton of 14,15-dimethyl-7,13-dioxotricyclic[6.4.0.0^9,11]dodeca-12,13-olide, and was established on the basis of spectroscopic methods including 2D-NMR. The coexistence of naupliolide 1 together with the structurally related sesquiterpene lactones asterisculolides A-D (3a-d) and 6,7,9,10-tetradehydroasteriscanolide 2, seems to indicate their biosynthetic relationship.     

A new germacranolide-type sesquiterpene lactone from Tanacetum santolinoides

A new germacranolide-type sesquiterpene lactone, 1alpha-hydroxy-3-oxo-7alpha,11betaH-germacra-4Z,9Z-dien-12,6alpha-olide (1), was isolated from the CH2Cl2--MeOH extract of the aerial parts of Tanacetum santolinoides. Its structure was determined by spectroscopic techniques including, IR, high-resolution-EIMS, and extensive 400 MHz one- and two-dimensional NMR-analysis (1H, 13C-NMR, DEPT, 1H--1H COSY, HMQC, HMBC, and NOE experiments).