Rapid construction of the [5–6–6] tricyclic core of sinudenoids B–D enabled by a tandem oxidation-intramolecular Diels–Alder reaction

Abstract

Sinudenoids B–D are a class of C19-norcembranoids characterized by a unique [5–5–6–6] tetracyclic architecture and notable bioactivities, which present significant synthetic challenges. We herein disclose an efficient strategy for the asymmetric construction of their common [5–6–6] tricyclic core. Our approach features two pivotal advancements: (1) a convergent strategy employing Julia–Kocienski olefination for efficient fragment coupling and (2) a tandem oxidation/intramolecular Diels–Alder (IMDA) sequence that stereoselectively establishes the [5–6–6] tricyclic core.