On the basis of Woodward–Hoffmann frontier molecular orbital interactions and steric interactions between dienes and dienophiles during the formation of [2+ 4] pericyclic transition states, endo/exo selectivity in the Diels–Alder reaction strongly depends on the substrates.[1] Therefore, it is quite difficult to control both enantioselectivity [2] and anomalous endo/exo selectivity by conventional chiral catalysts, which can discriminate ...