Mechanistic aspects of palladium-catalyzed allylstannylation of alkynes

An alpha-methylallylstannane added to an alkyne in the presence of a palladium catalyst with perfect regioselectivity both in the allylic and alkynic moieties. Comparison of the reaction of isomeric butenylstannanes suggests two catalytic cycles, one of which includes a palladacyclopentene intermediate and beta-tin elimination pathway.