Formal total synthesis of (+/-)-alpha- and beta-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.