Metal-ion-catalyzed Fluxionality of Pentadienyltins and Its Application to the Diels–Alder Reaction
(Z)-Pentadienyltins (PDT) as well as (Z)-allylic tins are isomerized to (E)-isomers most effectively by alkaline earth metal ions. The resulted (E)-PDT is trapped by 1,4-naphthoquinone to give the Diels–Alder adducts efficiently behaving as a reactive equivalent of 1,3-pentadiene.