Optically active chiral diphosphine ligands

Use of an (R) or (S) chiral diphosphine of formula (I):

• /insert formula (I), top of page 26/
• in which:
• R and R1, which can be identical or different, represent an optionally saturated C1-10 alkyl group, an optionally saturated C3-9 cycloalkyl group, a C5-10 aryl group, said groups being optionally substituted by a halogen, an hydroxy, a C1-5 alkoxy, an amino such as NH2, NHR4, N(R4)2, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, said alkyl, cycloalkyl, aryl groups optionally comprising one or more heteroatoms such as O, N, S, Si,
• or R and R1 together represent an optionally saturated C2-6 substituted alkyl group, an optionally saturated C3-9 cycloalkyl group, a C5-10 aryl group, said cycloalkyl or aryl groups being optionally substituted by a C1-5 alkyl, a halogen, an hydroxy, a C1-5 alkoxy, an amino such as NH2, NHR4, N(R4)2, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, said alkyl, cycloalkyl, aryl groups optionally comprising one or more heteroatoms such as O, N, S, Si,
• R2 and R3, which can be identical or different, represent an optionally saturated C3-8 cycloalkyl group, a C6-10 aryl group, said groups being optionally substituted by a halogen, an hydroxy, a C1-5 alkoxy, an amino such as NH2, NHR4, N(R4)2, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, said cycloalkyl, aryl groups optionally comprising one or more heteroatoms such as O, N, S, Si,
• or R2 and R3 together form an optionally saturated C4-8 carbocycle group, a C6-10 aryl group, said groups being optionally substituted by a halogen, an hydroxy, a C1-5 alkoxy, an amino such as NH2, NHR4, N(R4)2, a sulfino, a sulonfyl, with R4 representing an alkyl, an alkoxy or an alkylcarbonyl, said carbocycle, aryl groups optionally comprising one or more heteroatoms such as O, N, S, Si,
• as optically active ligand for preparation of a diphosphino-metal complex.