Cationic Platinum-Complex-Catalyzed Skeletal Reorganization of Enynes

The skeletal reorganization of 1,6-enynes into 1-vinylcyclopentenes was catalyzed by a cationic platinum complex under extremely mild conditions. The unusual rearrangement of the carbon skeleton, involving the cleavage of both the double and triple carbon−carbon bonds, was observed in certain cases and confirmed by 13C- and 2H-labeling experiments. Reaction mechanisms describing the rearrangement of carbocations are proposed.