Steroid-like ring skeletons by cyclohexadiene annulation to enamines with alkynylcarbene complexes of chromium and tungsten via pyran-2-ylidene complexes

A simple two-step procedure involving the condensation of a 1-alkynylcarbene complex with an enolizable carbonyl compound to afford a pyran-2-ylidene complex, which is subsequently reacted with an enamine to give the cyclohexadiene annulation product is used successfully for the syntheses of steroid-like ring skeletons. Bicyclic ring skeletons, steroid-like molecules and tetracyclic compounds are obtained mainly in good chemical yields and under mild conditions.