Catalyst for asymmetric (transfer) hydrogenation
View Patent ↗Catalyst for the asymmetric (transfer) hydrogenation represented by the formula ML a X b S c , where M is a transition metal, to be chosen from rhodium and ruthenium, and X is a counter ion and S is a ligand, a ranges from 0.5 to 3 and b and c, each independently, range from 0 to 2, and L is a chiral ligand having the formula (1), where C n together with the two 2 O-atoms and the P-atom forms a substituted or non-substituted ring with 2-4 C-atoms, R 1 and R 2 each independently represent H, an optionally substituted alkyl, aryl, alkaryl or aralkyl group or may form a (heterocyclic) ring together with the N-atom to which they are bound. And a process for the asymmetric (transfer) hydrogenation of an olefinically unsaturated compound, ketone, imine or oxime derivate in the presence of a hydrogen donor and of a catalyst, use being made of a catalyst represented by formula ML a X b S c , where M is a transition metal, to be chosen from rhodium, iridium and ruthenium, X is a counter ion, S is a ligand, a ranges from 0.5 to 3 and b and c range from 0 to 2, and L is a chiral ligand having the formula (1), where C n together with the two 2 O-atoms and the P-atom forms a substituted or non-substituted ring with 2-4 C-atoms; and R 1 and R 2 are as defined above.
1. A compound of the formula
ML a X b S c ,
wherein M is rhodium or ruthenium;
X is a counter ion;
S is a ligand;
a is 0.5-3; b and c each independently is 0 to 2; and
wherein L is a chiral ligand having one phosphorus atom of the formula
wherein C n is substituted or unsubstituted alkylene of 2-4 C-atoms;
R 1 and R 2 are each independently H, an optionally substituted alkyl, aryl, alkaryl or aralkyl or R 1 and R 2 form a heterocyclic ring together with the N-atom to which they are bound.
2. The compound of claim 1 , wherein C n represents a chiral substituted C 4 chain that has substantially one particular configuration.
3. The compound of claim 2 , wherein C n represents two pairs of adjacent C-atoms wherein each pair forms part of an aryl group or of a naphthyl group.
4. The compound of claim 1 wherein R 1 and R 2 are independently alkyl.
5. The compound of claim 1 , comprising a chiral ligand selected from the group consisting of
wherein each R 1 and R 2 is as defined in claim 1 .
6. A method for the preparation of a ligand of formula (1) as defined in claim 1 , which method comprises
(a) reacting a diol having the formula HO—C n —OH where C n is as defined in claim 1 with P(N(R 3 ) 2 ) 3 wherein R 3 is methyl or ethyl, followed by;
(b) treating the resultant of (a) with R 1 R 2 NH, wherein R 1 and R 2 are each independently optionally substituted alkyl, aryl, alkaryl or aralkyl or together form a heterocyclic ring with the N-atom to which they are bound.
7. A process for the asymmetric hydrogenation or asymmetric transfer hydrogenation, comprises treating a substrate with a hydrogen donor in the presence of a compound having formula
ML a X b S c ,
wherein M is rhodium or ruthenium;
L, X, S, a, b and c are as defined in claim 1 , to form a product.
8. The process of claim 7 wherein said substrate is an olefinically unsaturated compound, a ketone, an oxime, or an imine.
9. The process of claim 7 wherein C n in formula 1 represents a chiral substituted C 4 chain that has substantially one particular configuration.
10. The process of claim 9 wherein C n represents two pairs of adjacent C-atoms wherein each pair forms part of an aryl group or of a naphthyl group.
11. The process of claim 7 which is carried out in the presence of a non-protic solvent.
12. The process of claim 7 which is carried out in the presence of an ionic liquid.
13. The process of claim 7 wherein the hydrogen donor is selected from the group consisting of hydrogen, isopropanol and a mixture of formic acid and triethylamine.
14. The process of claim 7 which is carried out at a pressure of between 0.1 and 10 MPa.
15. The process of claim 7 wherein the substrate is an olefin, a ketone or an imine and wherein said substrate contains a chiral centre.
16. The process of claim 7 wherein compound having formula ML a X b S c is prepared in situ.
17. The process of claim 7 , further comprising treating said substrate in a solvent, wherein the substrate and/or the product forms a slurry with the solvent.
18. The compound of claim 1 , comprising the chiral ligand