Enantioselective Diels–Alder Reactions with Anomalous endo/exo Selectivities Using Conformationally Flexible Chiral Supramolecular Catalysts

Swapped selectivities: The use of tailor-made catalysts results in anomalous endo/exo selectivities and high enantioselectivities in the Diels–Alder reactions of cyclopentadiene with different acroleins (see scheme). These supramolecular catalysts are prepared in situ from chiral diols, arylboronic acid, and tris(pentafluorophenyl)borane, and can discriminate the re/si face of the dienophile as well as the endo/exo approach of the diene.