A composition comprising a chiral, bidentate bisphosphine ligand and additionally at least one compound of the general formula (I): in which R 1 , R 2 : are identical or different and are C 6 - to C 10 -aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino; Z is a group CHR 3 R 4 , in which R 3 is C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 -to C 6 -cycloalkyl or C 6 - to C 10 -aryl, wherein one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom; R 4 is C 1 - to C 4 -alkyl which is unsubstituted or carries a group P(=O) R 4a R 4b , C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxy-C 1 -to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, wherein one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom, and wherein C 3 - to C 6 -cycloalkyl and C 6 - to C 10 -aryl are unsubstituted or carry one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and amino; or R 3 , R 4 : together with the carbon atom to which they are bonded, are C 4 - to C 8 -cycloalkyl, in which one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom and wherein C 3 - to C 6 -cycloalkyl is unsubstituted or carries one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 -to C 4 -alkoxy and A-P (=O)R 4a R 4b , wherein A is a chemical bond or a C 1 - to C 4 -alkylene; and R 4a , R 4b : are identical or different and are phenyl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino. R 1 , R 2 : are identical or different and are C 6 - to C 10 -aryl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino; Z is a group CHR 3 R 4 , in which R 3 is C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy-C 1 - to C 4 -alkyl, C 3 -to C 6 -cycloalkyl or C 6 - to C 10 -aryl, wherein one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom; R 4 is C 1 - to C 4 -alkyl which is unsubstituted or carries a group P(=O) R 4a R 4b , C 1 - to C 4 -alkoxy, C 1 - to C 4 -alkoxy-C 1 -to C 4 -alkyl, C 3 - to C 6 -cycloalkyl or C 6 - to C 10 -aryl, wherein one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom, and wherein C 3 - to C 6 -cycloalkyl and C 6 - to C 10 -aryl are unsubstituted or carry one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 - to C 4 -alkoxy and amino; or R 3 , R 4 : together with the carbon atom to which they are bonded, are C 4 - to C 8 -cycloalkyl, in which one or two non-adjacent CH 2 groups in C 3 - to C 6 -cycloalkyl can also be replaced by an oxygen atom and wherein C 3 - to C 6 -cycloalkyl is unsubstituted or carries one or more substituents which are selected from C 1 - to C 4 -alkyl, C 1 -to C 4 -alkoxy and A-P (=O)R 4a R 4b , wherein A is a chemical bond or a C 1 - to C 4 -alkylene; and R 4a , R 4b : are identical or different and are phenyl which is unsubstituted or carries one or more substituents which are selected from C 1 - to C 6 -alkyl, C 3 - to C 6 -cycloalkyl, C 6 - to C 10 -aryl, C 1 - to C 6 -alkoxy and amino. <EOS>