Rhodium(I)-Catalyzed Ene-Allene Carbocyclization Strategy for the Formation of Azepines and Oxepines

A novel strategy for the preparation of seven-membered heterocyclic compounds has been realized. Treatment of ene-allene 1 with a catalytic quantity of rhodium biscarbonyl chloride dimer affords the cyclization product 2 in moderate to high yields. The scope and limitations of this new method are currently under investigation, and the results obtained to date are discussed within.