Synthesis of the Tetracyclic Core of the Kempanes by a Ring-Closing Metathesis Strategy

Abstract

The synthesis of the tetracyclic ring system of the kempane diterpenes was achieved through the highly regio- and stereoselective Diels−Alder reaction of an isopropenyl-diene with 2,6-dimethyl-p-benzoquinone, addition of an allyl group, and ring-closing metathesis of the isopropenyl and allyl groups