Stereoselective and Modular Assembly Method for Heterocycle-Fused Daucane Sesquiterpenoids

A stereoselective synthetic method is reported for the molecular framework found in common daucane and isodaucane sesquiterpenoid natural products. The synthetic method constitutes a scalable, modular, and also asymmetric access to a complex natural product scaffold, wherein the substitution pattern and the stereochemistry can be adjusted simply by choosing different starting materials. The method allows the rapid introduction of diverse heterocyclic substructures such as (benzo)furans, (benzo)thiophenes, dithiins, thiazoles, and indoles, which actually also facilitate and direct the key intramolecular annulation step.