Diphosphines

Abstract

A non-symmetrical diphosphine of the formula R 1 R 2 P—(Z)—PR 3 R 4 said diphosphine not having C 2 symmetry, wherein Z represents a chain of 2 to 4 carbon atoms which may be substituted, which chain may be saturated or unsaturated, and R 1 , R 2 , R 3 and R 4 each independently are aliphatic, aromatic or heteroaromatic groups attached to the phosphorus by carbon, nitrogen, oxygen or sulphur such that each of the moieties R 1 R 2 P and PR 3 R 4 contains a chiral centre.

1 . A non-symmetrical diphosphine of the formula 
       R 1 R 2 P—(Z)—PR 3 R 4   
       said diphosphine not having C 2  symmetry, wherein Z represents a chain of 2 to 4 carbon atoms which may be substituted, which chain may be saturated or unsaturated, and R 1 , R 2 , R 3  and R 4  each independently are aliphatic, aromatic or heteroaromatic groups attached to the phosphorus by carbon, nitrogen, oxygen or sulphur such that each of the moieties R 1 R 2 P and PR 3 R 4  contains a chiral centre.  
     
     
         2 . A diphosphine according to  claim 1 , wherein Z represents a chain of 2 carbon atoms.  
     
     
         3 . A diphosphine according to  claim 1 , wherein R 1  and R 2  are linked, and/or R 3  and R 4  are linked, to form a substituted or unsubstituted 3, 4, 5, 6 or 7 membered phosphorus heterocycle.  
     
     
         4 . A diphosphine according to  claim 3 , wherein R 1  and R 2  are linked to form a ring of the formula:  
       
         
           
           
               
               
           
         
       
       wherein R 5  and R 6 , which may be the same or different, are hydrogen, hydroxy or C 1  to C 4  alkoxy and R 9  and R 10 , which may be the same or different, are hydrogen or C 1  to C 4  alkyl, and all of R 5 , R 6 , R 9  and R 10  cannot be hydrogen at the same time.  
     
     
         5 . A diphosphine according to  claim 1 , wherein at least one of R 1 , R 2 , R 3  and R 4  is substituted or unsubstituted phenyl.  
     
     
         6 . A diphosphine according to  claim 5 , wherein the phenyl group is substituted by one or more hydroxy groups.  
     
     
         7 . A diphosphine according to  claim 5 , wherein the phenyl group is substituted by one or more or C 1  to C 4  alkoxy groups.  
     
     
         8 . A diphosphine according to  claim 1  wherein at least one of the phosphorus atoms is ligated to a borane.  
     
     
         9 . A catalyst comprising a diphosphine as claimed in  claim 1  and a metal.  
     
     
         10 . A catalyst according to  claim 9 , wherein the metal is rhodium, iridium, ruthenium, palladium or platinum.  
     
     
         11 . A catalyst according to  claim 9 , wherein the catalyst is neutral or cationic.  
     
     
         12 . A cationic catalyst according to  claim 11 , wherein the counterion is halide, tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, sulfonate of the formula R 7 SO 3 , wherein R 7  is an aliphatic or aromatic group, or boronate of the formula (R 8 ) 4 B, wherein the groups R 8 , which may be the same or different, are aromatic groups.  
     
     
         13 . A process for preparing a diphosphine as defined in  claim 1 , which process comprises reacting a nucleophilic phosphorus-containing reactant with an unsaturated phosphorus containing reactant or a cyclopropyl phosphorus containing reactant.  
     
     
         14 . A process according to  claim 13 , wherein the nucleophilic phosphorus-containing reactant is an enantiomerically pure phosphine.  
     
     
         15 . A process according to  claim 14 , wherein the phosphine is ligated to a borane.  
     
     
         16 . A process according to  claim 15 , wherein the enantiomerically pure phosphine is ortho-anisylphenylphosphine ligated to borane.  
     
     
         17 . A process according to  claim 13 , wherein the unsaturated phosphorus containing reactant is an oxidised phosphorus-bonded alkene.  
     
     
         18 . A process according to  claim 17 , wherein the alkene is ethene or 1,3-butadiene.  
     
     
         19 . A process according to  claim 13 , wherein a diphosphine intermediate comprising a primary phosphine and a tertiary phosphine is produced.  
     
     
         20 . A process according to  claim 19 , wherein the primary phosphine is converted into a phosphorus heterocycle.  
     
     
         21 . A process according to  claim 20 , wherein the phosphorus heterocycle is formed by reaction of the primary phosphine with an enantiomerically pure diol activated by conversion of the hydroxyl groups into leaving groups.  
     
     
         22 . A process according to  claim 21 , wherein the diol is activated by conversion into a halogen derivative, sulphate, sulfonate or phosphate.  
     
     
         23 . A process according to  claim 21 , wherein the diol is mannitol.  
     
     
         24 . A process for the asymmetric catalytic conversion of a compound, wherein the catalyst is one claimed in  claim 9 .  
     
     
         25 . A process according to  claim 24 , wherein the compound is asymmetrically hydrogenated.  
     
     
         26 . A process according to  claim 24 , wherein the compound is an unsaturated ester.