Asymmetric Hetero Diels-Alder Reaction Catalyzed by Chiral Ytterbium(III) Phosphate{Yb[(R)-(-)-BNP]3}: Remarkable Ligand Effect on the Enantioselectivity - Hanamoto, T; Furuno, H; Sugimoto, Y; Inanaga, J (Synlett, 1997)