A Domino Diels–Alder Approach toward the Tetracyclic Nicandrenone Framework

The tetracarbocyclic framework of the nicandrenone natural products is formed in one step from a linear precursor via a domino intramolecular Diels–Alder/intramolecular furan Diels–Alder/aromatization sequence. The approach represents a new 0 → ABCD strategy for the preparation of aromatic steroids.