Intramolecular, Interrupted Homo‐Nazarov Cascade Biscyclizations to Angular (Hetero)Aryl‐Fused Polycycles

Herein, a SnCl4‐catalyzed intramolecular, interrupted homo‐Nazarov cascade biscyclization to access angular (hetero)aryl‐fused polycycles is reported. Subsequent decarboxylation of the readily enolizable products afforded the angular products in up to 71 % yield over two steps, with the trans‐diastereomers as the major products. The cyclopropyl homo‐Nazarov cyclization precursors were formed using a scalable and modular synthetic route that, ultimately, offers access to 6,6,6‐, 6,6,5‐, 6,5,6‐, 6,6,5,6‐, and 6,6,6,5‐fused angular polycyclic products. To showcase the rigor and utility of the method, an 8‐step total synthesis of (±)‐1‐oxoferruginol, an antibacterial aromatic abietane diterpenoid, was disclosed. Alkenyl cyclopropyl ketones tethered to (hetero)arenes readily underwent catalytic, intramolecular interrupted homo‐Nazarov cascade biscyclizations to form 6,6,6‐, 6,5,6‐, 6,6,5‐, 6,6,6,5‐, and 6,6,5,6‐fused angular architectures. The approach was used for the concise total synthesis of (±)‐1‐oxoferruginol, a bioactive abietane diterpenoid.