Transition‐Metal‐Catalyzed Allylic Substitution and Titanocene‐Catalyzed Epoxypolyene Cyclization as a Powerful Tool for the Preparation of Terpenoids

Abstract

Abstract Many biologically active substances are composed of sesquiterpene units linked to aromatic structures, especially substituted phenols. Here, we describe an efficient synthetic approach to this class of natural product from commercially available substances in a short sequence. The key transformations involve allylic substitution reactions using a palladium or copper catalyst and titanocene‐catalyzed epoxypolyene cyclization reactions via radicals. The polycyclic core structures are accessed with high chemo‐ and stereocontrol. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)