Formal Total Synthesis of (±)-α- and β-Cedrene by Preparation of Cedrone. Construction of the Tricyclic Carbon Skeleton by the Use of a Highly Efficient Intramolecular Khand Annulation

The cedrene carbon skeleton was rapidly assembled from a simple monocyclic precursor by the strategic use of a high yielding intramolecular Khand cyclization reaction. Further synthetic manipulations provided a concise formal total synthesis of alpha- and beta-cedrene. Reaction: see text.