Search results for "RPE"
showing 10 items of 2566 documents
A minor diterpene from Amaracus akhdarensis
1985
Abstract A new isopimarane diterpenoid, isoakhdartriol, was isolated in very small amount from the aerial part of Amaracus akhdarensis. Its structure, isopimar-15-en-3β,8β,19-triol, was established by spectroscopic means.
ChemInform Abstract: 4,4,4′,4′,7,7′-Hexamethyl-2,2′-spirobichroman.
2010
The title compound, C23H28O2, was obtained from the reaction of acetone with meta-cresol. The molecular structure consists of two identical subunits which are nearly perpendicular to each other. The oxygen-containing rings are not planar and the molecule is chiral. The crystal structure consists of chains of molecules of the same chirality arranged along the [010] axis.
Jatrophane and tigliane diterpenes from the latex of Euphorbia obtusifolia
1999
The latex of Euphorbia obtusifolia var. obtusifolia yielded twelve new diterpene polyesters. Seven of them displayed the jatrophane framework and five were 4-deoxyphorbol esters. A further isolated tigliane diterpene, a derivative of 4-epi-4-deoxyphorbol, was most likely an artifact of the isolation procedure. All structures were established with the aid of spectroscopic methods.
13C nuclear magnetic resonance spectra of several podocarpane and cassane diterpenoids
1990
The 13C NMR spectra of several diterpenic derivatives having the podocarpane and cassane skeleton were recorded and interpreted. The most significant effects due to substituent orientation, B/C ring junction stereochemistry and conformational changes are briefly discussed.
New Sesquiterpene Lactones and Other Constituents fromCentaurea paui
1997
Aerial parts of Centaurea paui afforded, in addition to several known sesquiterpene lactones, the two new elemanolides 2–4, the new elemane derivative 5 as well as the five new heliangolides 14–18. Their structures were elucidated by spectroscopic methods, especially high-field NMR spectroscopy. The structure of the heliangolide 12 previously isolated from this plant, has been confirmed by X-ray diffraction.
A sesquiterpene ester from Lactuca serriola
1992
Abstract The aerial parts of Lactuca serriola yielded a new guaiane ester together with five known guaianolides.
Synthesis of Elemane Bis-Lactones from Santonin – Synthesis of the Reported Structure ofseco-Isoerivanin Pseudo Acid and Formal Synthesis of (+)-8-De…
2000
The synthesis of the reported structure for seco-isoerivanin pseudo acid (1) and of an elemane bis-lactone 5 from santonin (4) through a common vinylic precursor 12 is described. Compound 5 is a known intermediate in a previous synthesis of the antitumor compound (+)-8-deoxyvernolepin (3). The vinyl group of 12 underwent a regio- and diastereoselective anti addition of an external electrophile and an intramolecular condensation to yield either the selenolactone 13 or the hydroxylactone 17. The lactones 13 and 17 served as key intermediates in the total synthesis of 1 and 5 respectively. A revision of the structure of seco-isoerivanin pseudo acid to the C-10 epimer is suggested on the basis …
ChemInform Abstract: Transformation of Artemisin Into Artapshin and 8α-Hydroxy-11β,13-Dihydrobalchanin.
1987
Abstract Partial syntheses of the sesquiterpene lactones artapshin ( 1 ) and 8α-hydroxy-11β, 13-dihydrobalchanin ( 2 ) from artemisin ( 3 ) are described.
Chemical Composition of the Essential Oils ofPistacia atlanticaDesf.
2005
The chemical composition of the three essential oils obtained by hydrodistillation of the resin, leaves and fruits of Pistacia atlantica Desf. (Anacardiaceae) was studied by GC and GC/MS. Monoterpene hydrocarbons constituted the main chemical group in the resin oil, with α-pinene (42.9%) and β-pinene (13.2%) as the major components. Oil of the fruits contained high amounts of oxygenated monoterpenes, with bornyl acetate (21.5%) as the major component, while oxygenated monoterpenes and sesquiterpenes were found to predominate in the oil of leaves among which terpinen-4-ol (21.7%) and elemol (20.0%) were the most abundant components.
A diterpene, distanol, from Sideritis distans
1989
Abstract A new diterpene, distanol, has been isolated from the petrol extract of the aerial part of Sideritis distans Wild. Its structure stereochemistry has been assigned by spectroscopic methods.