Total Syntheses of Durgamone, Nakorone, and Abudinol B via Biomimetic Oxa- and Carbacyclizations

The first biomimetic total syntheses of ent-nakorone, ent-durgamone, and ent-abudinol B were accomplished by combining features of tandem polyepoxide cyclization with biomimetic polyene cyclization. The present biomimetic synthesis route offers efficient access to these marine natural products. In addition, the synthesis of the tetrasubstituted alkene of ent-abudinol B demonstrates the application of palladium-catalyzed cross-coupling of two different polycyclic ketones via the corresponding vinyl triflates, followed by partial hydrogenation of the resulting conjugated diene.