Method for preparing chiral diphosphines

A process for preparing a compound of formula I:

• in which:
• A represents an optionally substituted phenyl or naphthyl;
• and
• Ar1 and Ar2 independently represent an optionally substituted saturated or aromatic carbocyclic group;
• this process comprising the steps comprising:
• i) brominating a diol of formula II:
• in which A is as defined above, using a suitable brominating agent so as to obtain a dibromo compound of formula III:
• in which A is as defined above;
• ii) esterifying the compound of formula III obtained in the preceding step by the action of a sulfonic acid or an activated form thereof, so as to obtain the corresponding disulfonate;
• iii) substituting the two bromine atoms with cyano groups by reacting the disulfonate obtained in the preceding step with a suitable nucleophilic agent so as to obtain the corresponding nitrile;
• iv) coupling a phosphine of formula VI:
• XPAr1AR2 (VI)
• in which X represents a hydrogen atom or a halogen atom and Ar1 and Ar2 are as defined above, with the nitrile obtained in the preceding step, in the presence of a catalyst based on a transition metal, so as to obtain the compound of formula I.