Highly Rigid Diphosphane Ligands with a Large Dihedral Angle Based on a Chiral Spirobifluorene Backbone

Abstract

High and wide: The high rigidity and large dihedral angle of chiral, spirobifluorene-based diphosphane ligands lead to excellent reactivity and enantioselectivity in the ruthenium-catalyzed asymmetric hydrogenation of α,β-unsaturated carboxylic acids (see scheme).