Bidentate secondary phosphine oxide chiral ligands for use in asymmetric addition reactions

摘要

Compounds of the formula I, in the form of mixtures comprising predominantly one enantiomer or in the form of pure enantiomers, secondary phosphine-Q-P*(═O)HR₁ (I) in which secondary phosphine is a C-bonded, secondary phosphine group —P(R)₂; in which R is in each case independently hydrocarbon radicals or heterohydrocarbon radicals; Q is a bivalent, achiral, aromatic base skeleton, a bivalent, achiral ferrocene base skeleton, an optionally substituted bivalent cycloalkane or heterocycloalkane skeleton, or a C1-C4-alkylene skeleton, and in which base skeletons a secondary phosphine group is bonded directly to a carbon atom, or, in the case of cyclic base skeletons, directly to a carbon atom or via a C₁-C₄-alkylene group, and in which base skeletons a P-chiral group —P*(O)HR₁ is bonded to a carbon atom such that the phosphorus atoms are linked via 1 to 7 atoms of a carbon chain optionally interrupted by heteroatoms from the group of O, S, N, Fe or Si; P* is a chiral phosphorus atom; and R₁ is a hydrocarbon radical, a C-bonded heterohydrocarbon radical or a ferrocenyl radical, with the proviso that R₁ is an achiral ferrocenyl radical when Q is an achiral ferrocenyl base skeleton. Metal complexes of these ligands in a molar ratio of ligand to metal of about 1.3:1 to 0.9:1 are homogeneous catalysts for asymmetric addition reactions, particularly hydrogenations.