Figure 1. Perspective views of bicyclo [5.3. l] undecenone and bicyclo [4.3. l] decenone. these enones increased with the lower (and more highly distorted) homologues, we were led to explore representatives of the next lower homologue, the bicyclo [3.2. l] octane system. In this paper, reaction sequences are described that lead to the transient formation of the bicyclic enones 4 and 5 (Chart I).