Synthesis of the Tetracyclic Bis(acetal) Lactone Portion of Saudin

Abstract

AbstractTwo synthetic approaches towards the synthesis of the tetracyclic lactone 4, containing the caged bis(acetalic) backbone of Saudin, were explored. Both sequences included the utilization of the known epoxy‐acetal 3, prepared stereoselectively by means of an intramolecular radical cyclization, as the common key intermediate, allowing total control over the relative stereochemistry of four consecutive chiral centers. Oxidative degradation with ruthenium dioxide and unsymmetrical ozonolysis reactions provided the new two key synthons in each synthetic route. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)