A new class of C2-symmetric 3,3′-dialkoxy-2,2′-bipyrrolidines have been designed and developed for asymmetric organocatalyticDiels–Alderreactions of α,β-unsaturated aldehydes. The bipyrrolidines combined with HClO4 were found to be effective organocatalysts for enantioselectiveDiels–Alderreactions. The catalysis mode has been demonstrated by NMR and X-ray crystallographic studies for diiminium
Can achiral organocatalysts linked to chiral polyanionic metal oxideclusters provide good selectivity in enantioselective CC bond formations? The answer to this question is investigated by developing a new active hybrid polyoxometalate‐based catalyst for asymmetric Diels–Alder reaction. Chiralitytransferfrom the chiral anionic polyoxometalate to the covalently linked achiral imidazolidinone allows
supramolecular boron Lewisacidcatalysts were prepared from chiral 3-phosphoryl-1,1′-bi-2-naphthols, (2-cyanophenyl)boronic acids, and tris(pentafluorophenyl)borane, bound through CN···B and PO···B coordination bonds. In particular, the coordinated tris(pentafluorophenyl)boranes increase the Lewis acidity of the active center in the manner of a LewisacidassistedLewisacidcatalyst system. A possible