A Fused Hexacyclic Ring System: Diastereoselective Polycyclization of 2,4‐Dienals through an Interrupted iso‐Nazarov Reaction

We report an unprecedented domino polycyclization from readily available 2,4‐dienals and cyclic α,β‐unsaturated imines that is initiated by an iso‐Nazarov reaction. This Brønsted acid promoted reaction enables the concomitant formation of four bonds, three cycles, and four contiguous stereogenic centers to yield elaborated structures in a single operation. A range of fused hexacyclic molecules is obtained in a highly diastereoselective manner.