Acid‐Induced Rearrangement of Epoxygermacra‐8,12‐olides: Synthesis and Absolute Configuration of Guaiane and Eudesmane Derivatives from Artemisiifolin

Abstract A study on the acid‐induced rearrangement of 4,5‐epoxy‐ and 1,10‐epoxygermacra‐8,12‐olides was carried out. From a 4,5‐epoxy derivative, guaianes were obtained, whereas 1,10‐epoxy derivatives furnished, depending on the stereochemistry of the C‐1/C‐10 epoxy ring, trans ‐5β,10α‐ or trans ‐5α,10β‐eudesmanolides.