Chemistry of alkylaromatic metallacycles. Regiochemistry of CC coupling in ring opening or enlargement reactions of a palladacycle with alkynes

Abstract A phenylnorbornylpalladacycle containing methyl isonicotinate ligands was shown to undergo either ring opening or ring enlargement by reaction with acetylenic compounds to give norbornylalkynes regioselectively and ring-enlarged tetracyclic compounds non-regioselectively. However, in the case of ethyl propiolate regioselective ring enlargement takes place.