The 2π + 2π cycloaddition of an allyl cation to (1Z,3E)-cycloalkadienes. Evidence for a stepwise process in the ionic Diels-Alder reaction

Article abstract of DOI:10.1016/S0040-4039(00)97098-9

Treatment of (1Z,3E)-cycloalkadienes with 2-vinyl-1,3-dioxolane under acidic conditions produced 1:1 cycloadducts in which an intermediate allyl cation added to the dienes to give trans-fused cyclobutanes as the major products.