Bicyclopropylidene derivatives 1, 6, 8 with furan moieties attached on tethers of various length and nature all undergo clean intramolecular Diels-Alder reactions with complete endo-diastereoselectivities when heated to 70–130° C, under 10 kbar pressure. The reaction rates are at least as high or higher than those of analogously tethered methylenecyclopropane-furan derivatives 15, 17, 20, in spite of the fact that the reactive ...
