PtCl2-catalyzed conversion of 1,6- and 1,7-enynes to 1-vinylcycloalkenes. Anomalous bond connection in skeletal reorganization of enynes

The treatment of 1,6- and 1,7-enynes with a catalytic amount of PtCl2 in toluene at 80 degrees C results in sheletal reorganization (cyclorearrangement) of the enynes to give 1-vinylcycloalkenes in high yields. A deuterium labeling experiment indicates that two mechanistic paths are operating for the cyclorearrangement. The nature and position of substituents affect the reaction course. Anomalous carbon-carbon bond formation is attained selectively in the reaction of 1,6-enynes having an, ester group at the terminal acetylenic carbon.