A new type of atropisomeric bisphosphine ligand 2 with a bridge across the 5,5'-position of the biphenyl has been developed. The axial chirality of this type of ligands can be retained by macrocyclic ring strain produced from 5,5'-linkage of the biphenyl even without 6,6'-substituents on the biphenyls. Ligand (R)-2a showed good catalytic activity and enantioselectivity for Rh(I)-catalyzed asymmetric hydrogenation of (Z)-alpha-acetamidocinnamic acid 11. (C) 2008 Elsevier Ltd. All rights reserved.
Atropisomeric bisoxazoline ligands with a bridge across the 5,5′-position of biphenyl for asymmetric catalysis
be retained by macro-ring strain produced by 5,5′-linkage of biphenyls even without 6,6′-substituents on biphenyls. The Pd(II)-2d complex as catalyst showed high catalytic activity and enantioselectivity for asymmetricWacker-typecyclization of allylphenols.