Intramolecular Cyclohexadienone Annulations of Fischer Carbene Complexes:  Model Studies for the Synthesis of Phomactins

The intramolecular cyclohexadienone annulation of chromium carbene complexes is examined as a method to provide general access to the Phomactin family of natural products. The importance of the stereochemistry of the carbene complex and the number of carbons in the tether connecting the carbene complex and the alkyne are probed. Additionally, the degree of the 1,4-asymmetric induction is examined.