A variety of vinylic bromoalkenyl alkenyl ethers were reacted with piperidine and a palladium acetate-trio-tolylphosphine catalyst. Intramolecular vinylic substitution occurred in many cases. Five-membered rings formed most easily, followed by six and then seven. Larger rings were much more difficult to produce. Substitution at the reacting double bond sometimes altered the ring closure preference since the less substituted double bond ...
