The invention relates to novel bisphosphonates and to processes for their preparation and for their resolution into the enantiomers. The bisphosphonates according to the invention are valuable intermediates for the preparation of bisphosphine compounds, especially chiral bisphosphine ligands. These in turn are constituents of transition metal complexes which are used as catalysts inter alia in asymmetric hydrogenation. The novel bisphosphonates have the general formula (I) ##STR1## in which R.sup.1 is linear or branched alkyl having up to 6 carbon atoms, aryl or aralkyl, each of which can optionally be substituted, or two radicals R.sup.1 together are a bridging hydrocarbon radical having up to 6 carbon atoms, and can exist in the form of their racemates or as enantiomers.
本发明涉及新型双
磷酸盐以及它们的制备和分离对映体的过程。根据本发明,所述双
磷酸盐是制备手性
双膦化合物,特别是手性双
膦配体的有价值中间体。这些手性双
膦配体又是过渡
金属配合物的组成部分,这些配合物用作不对称氢化反应的催化剂等。新型双
磷酸盐具有通式(I):##STR1## 其中R.sup.1是直链或支链烷基,具有最多6个碳原子,芳基或芳基烷基,每个基团可以选择性地被取代,或者两个基团R.sup.1在一起是具有最多6个碳原子的桥式烃基团,并且可以存在于其外消旋体或对映体的形式。