Search results for "lactone"
showing 10 items of 335 documents
13C NMR spectra of eudesmanolides I—eudesman-12,6-olides
1987
The 13C NMR spectra of 26 eudesmanolides of natural and synthetic origin have been measured, including the naturally occurring sesquiterpene lactones artemisin, torrentin, rothin-A and rothin-B and several semi-synthetic eudesman-12,6-olides obtained from artemisin. The chemical shift values of the different compounds are compared and the effects of the substituents are discussed.
Sesquiterpene lactones from Artemisia lucentica
1997
Abstract The aerial parts of Artemisia lucentica yielded, in addition to several known compounds, a bicyclic monoterpene ketone, two germacranolides, an eudesmanolide, a 10- epi neudesmanolide, a 2-norelemanolide and three bisabolene derivatives. The stereochemistry of a germacranolide, described as 2α-hydroxyartemorin in a previous investigation of the species, has now been corrected and the compound has been renamed lucentolide.
A novel germacranolide-aminoacid adduct dimer from centaurea aspera
1991
Abstract The novel germacronolide-valine adduct dimer 1 has been isolated from aerial parts of Centaurea aspera var. aspera . Its structure has been determined by spectroscopic methods.
Sesquiterpene lactones from iranian Artemisia species
1993
Abstract The aerial parts of Artemisia turcomanica and A. deserti yielded two new germacranolides, a new guaianolide, and several known mono- and sesquiterpenes.
Sesquiterpene lactones fromArtemisia barrelieri
1991
Abstract Extraction of aerial parts of Artemisia barrelieri and chromatographic separation yielded a new germacranolide, two new monocyclic sesquiterpenes and a novel germacranolide dimer, together with several known compounds.
Sesquiterpene lactones from Centaurea sphaerocephala ssp. sphaerocephala
1994
Abstract Aerial parts of Centaurea sphaerocephala ssp. sphaerocephala furnished sesquiterpene lactones commonly found in Centaurea species as well as a new germacranolide and a new elemadienolide.
Sesquiterpene lactones and dihydroflavonols from Andryala and Urospermum species
1994
Abstract The aerial parts of two Andryala species yielded several guaianolides and guaianolide glycosides, three of them being new. The aerial parts of Urospermum dalechampii yielded several known germacranolides and the new dihydroflavonol 3- O -methyltaxifolin.
Synthesis of polycaprolactone by microwave irradiation ? an interesting route to synthesize this polymer via green chemistry
2003
Poly(e-caprolactone) has become an important biocompatible and biodegradable polymer. Indeed, due to its multiple biomedical applications, the synthesis of polycaprolactone has received increased attention in the past few decades. Moreover, microwave irradiation is a very clean modern technique widely used for green chemistry. Here, several polymers were synthesized by microwave irradiation, without any solvent, using nontoxic, biologically acceptable lanthanide halides as initiators. Reaction times varied between 2 and 90 min. The molecular weights of the obtained polymer products were between 3,000 and 16,000 g/mol. After polymerization, the polycaprolactone polymers were functionalized b…
The Influence of Brassinosteroid, a Growth-promoting Steroidal Lactone, on Development and CO2-fixation Capacity of Intact Wheat and Mustard Seedlings
1984
In 1970, Mitchell et al. isolated a lipoidal complex from the pollen of rape (Brassica napus L.). This complex, called “Brassins” was found to have partly powerful growth-promoting properties. The novel growth response of young bean plants in the second internode assay (Worley, Mitchell 1971; Mitchell, Gregory 1972) and other physiological changes following Brassin-treatment have been studied under several aspects (Krizek, Worley 1981; Gregory 1981).
Stereoselective Synthesis of (+)-Boronolide
2002
The delta-lactone boronolide (+)-1, a pharmacologically active, naturally occurring product, has been synthesized in enantiopure form with L-erythrulose as the chiral starting material. The key steps of the synthesis were a highly stereoselective aldol-reduction one-pot sequence, an indium-mediated diastereoselective aldehyde allylation, and a ring-closing metathesis.