A composition comprising a chiral, bidentate bisphosphine ligand and additionally at least one compound of the general formula: 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.