1 research outputs found
15-Hydroxygermacranolides as Sources of Structural Diversity: Synthesis of Sesquiterpene Lactones by Cyclization and Rearrangement Reactions. Experimental and DFT Study
A study
on the electrophile-induced rearrangement of two 15-hydroxygermacranolides,
salonitenolide and artemisiifolin, was carried out. These compounds
underwent electrophilic intramolecular cyclizations or acid-mediated
rearrangements to give sesquiterpene lactones with different skeletons
such as eudesmanolides, guaianolides, amorphanolides, or other germacranolides.
The cyclization that gives guaianolides can be considered a biomimetic
route to this type of sesquiterpene lactones. The use of acetone as
a solvent changes the reactivity of the two starting germacranolides
to the acid catalysts, with a 4,15-diol acetonide being the main product
obtained. The Ī“-amorphenolide obtained by intramolecular cyclization
of this acetonide is a valuable intermediate for accessing the antimalarials
artemisinin and its derivatives. Mechanistic proposals for the transformations
are raised, and to provide support them, quantum chemical calculations
[DFT B3LYP/6-31+GĀ(d,p) level] were undertaken