41702-63-0Relevant academic research and scientific papers
Sesquiterpene Cyclizations inside the Hexameric Resorcinarene Capsule: Total Synthesis of δ-Selinene and Mechanistic Studies
Zhang, Qi,Tiefenbacher, Konrad
supporting information, p. 12688 - 12695 (2019/08/12)
The synthesis of terpene natural products remains a challenging task due to the enormous structural diversity in this class of compounds. Synthetic catalysts are unable to reproduce the tail-to-head terpene cyclization of cyclase enzymes, which create this diversity from just a few simple linear terpene substrates. Recently, supramolecular structures have emerged as promising enzyme mimetics. In the present study, the hexameric resorcinarene capsule was utilized as an artificial cyclase to catalyze the cyclization of sesquiterpenes. With the cyclization reaction as the key step, the first total synthesis of the sesquiterpene natural product δ-selinene was achieved. This represents the first total synthesis of a sesquiterpene natural product that is based on the cyclization of a linear terpene precursor inside a supramolecular catalyst. To elucidate the reaction mechanism, detailed kinetic studies and kinetic isotope measurements were performed. Surprisingly, the obtained kinetic data indicated that a rate-limiting encapsulation step is operational in the cyclization of sesquiterpenes.
The role of the 12-carboxylic acid group in the spontaneous autoxidation of dihydroartemisinic acid
Sy, Lai-King,Brown, Geoffrey D
, p. 909 - 923 (2007/10/03)
Three of the four steps in the slow spontaneous autoxidation of dihydroartemisinic acid to artemisinin ('ene-type' reaction of molecular oxygen with the Δ4,5 double bond, Hock cleavage of the resulting tertiary allylic hydroperoxide, oxygenation of the enol product from Hock cleavage and cyclization of the resulting vicinal hydroperoxyl-aldehyde to the 1,2,4-trioxane system of artemisinin) are shown to be assisted by the proximity of the 12-carboxylic acid functional group in dihydroartemisinic acid to the functional groups participating in these reactions.
The role of germacrene D as a precursor in sesquiterpene biosynthesis: Investigations of acid catalyzed, photochemically and thermally induced rearrangements
Buelow, Nils,Koenig, Wilfried A
, p. 141 - 168 (2007/10/03)
Germacrene D is considered as a precursor of many sesquiterpene hydrocarbons. We have investigated the acid catalyzed as well as the photochemically and thermally induced rearrangement processes of germacrene D isolated from several Solidago species, which contain both enantiomers of germacrene D. Enantiomeric mixtures of sesquiterpenes of the cadinane, eudesmane (selinane), oppositane, axane, isodaucane, and bourbonane group as well as isogermacrene D were identified as main products and made available as reference compounds for structure investigations and stereochemical assignments of plant constituents. δ-Amorphene, one of the rearrangement products, was identified as a natural product for the first time. The absolute configuration of γ-amorphene was revised by correlation with the absolute configuration of germacrene D. The mechanisms of the rearrangement reactions are discussed. (C) 2000 Elsevier Science Ltd.
STABLE CARBOCATIONS FROM TERPENOIDS.IX. MOLECULAR REARRANGEMENTS OF α-MUROLENE AND α-COPAENE WITH THE FORMATION OF TRICYCLIC COMPOUNDS
Polovinka, M. P.,Mamatyuk, V. I.,Korchagina, D. V.,Sal'nikov, G. E.,Gatilov, Yu. V.,et al.
, p. 863 - 882 (2007/10/02)
Tricyclic compounds were obtained from α-murolene and α-copaene in superacidic media, and this agrees with the scheme for the biogenetic transformations of these substances.It was found that the temperature at which the stable cations are generated from α-murolene has an effect on the ratio of the paths leading to the formation of the bi- and tricyclic ions.The prediction of the most probable paths for the transformation of α-copaene agrees with the actually observed transformation of the stable ions generated from this substance.The preferred direction in the ske letal rearrangements of the investigated compounds depends on the nature of the acid medium.
