An Efficient Method for Construction of the Angularly Fused 6,3,5-Tricyclic Skeleton of Mycorrhizin A and Its Analogues

The angularly fused 6,3,5-tricyclic system is readily generated via a cascade cyclization under acid promotion. The reaction proceeds at room temperature with high stereochemical fidelity from the electrophilic center of the epoxide to the cyclopropane product. This methodology provides a potentially useful approach for the synthesis of mycorrhizin A and its analogues.