Bidentate phosphorus ligands and their use in catalysis

Details Bidentate phosphorus ligands and their use in catalysis Bidentate phosphorus ligands and their use in catalysis

2001-10-24

2002-11-05

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

C558S155000, C568S006000

Reexamination Certificate

active

06476246

ABSTRACT:

BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to novel unsymmetrical chiral diphosphines and phosphine phosphinites and their synthesis and to complexes of these compounds with metals of groups VIIb, VIIIb and Ib of the Periodic Table and also to their use as catalysts for enantioselective transformations, in particular hydrogenations.
DISCUSSION OF THE RELATED ART
Trisubstituted organophosphorus compounds are of great importance as ligands in homogeneous catalysis. Variation of the substituents of phosphorus in such compounds enables the electronic and steric properties of the phosphorus ligands to be influenced in a tailored manner, so that selectivity and activity in homogeneously catalyzed processes can be controlled.
Enantiomerically enriched chiral ligands are used in asymmetric synthesis or asymmetric catalysis, where the important aspect is that the electronic and stereochemical properties of the ligand are optimally matched to the respective catalysis problem. There is therefore a great need for chiral ligands which are stereochemically and electronically different in order to find the optimum “tailored” ligand for a particular asymmetric catalysis.
The structural variety of phosphorus ligands known hitherto is very wide. These ligands can be classified, for example, according to class of substance and examples of such classes of substances are trialkylphosphines and triarylphosphines, phosphites, phosphinites, phosphonites, aminophosphines, etc. This classification according to class of substance is particularly useful for describing the electronic properties of the ligands.
Phosphorus ligands can also be classified according to their symmetry properties or according to the denticity of the ligands. This structuring takes account, in particular, of the stability, activity and stereoselectivity of metal complexes with phosphorus ligands as catalyst precursors or as catalysts. Apart from the widespread C
2
-symmetrical bidentate ligand systems such as DUPHOS, DIPAMP, BINAP or DEGUPHOS, unsymmetrical bidentate organophosphorus ligands are increasingly becoming the focus of asymmetric catalysis. Important examples are the large class of versatile chiral ferrocenylphosphine ligands such as JOSIPHOS, DPPM, the bisphosphinite ligands such as CARBOPHOS which are used particularly successfully in the asymmetric hydrogenation of olefins and imines, or the phosphine phosphite ligands such as BINAPHOS or BIPHEMPHOS which are used successfully in the asymmetric hydroformylation of olefins.
An important aspect of the success of these classes of compound is believed to be the creation of a particularly asymmetric environment around the metal center by these ligand systems. To utilize such an environment for an effective transfer of chirality, it is advantageous to control the flexibility of the ligand system as inherent limitation of the asymmetric induction.
Disadvantages of the chiral phosphorus ligand systems known hitherto are, firstly, their complicated synthesis and, secondly, the restricted opportunities for varying the properties of a given ligand skeleton, e.g. by the introduction of different substituents.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel, unsymmetrical, bidentate and chiral phosphorus ligand systems which can easily be varied in terms of their steric and electronic properties over an extraordinarily wide range.
This object is achieved by a class of chiral, unsymmetrical bidentate organophosphorus compounds of the formula (I) in which a chiral bicycloaliphatic skeleton is present.
The present invention accordingly provides compounds of the formula (I),
where
m and n may each be, independently of one another, 0 or 1 and
R1-R2 are, independently of one another, a radical selected from the group consisting of C
1
-C
24
-alkyl, C
3
-C
8
-cycloalkyl which may contain 1-2 heteroatoms selected from the group consisting of N, O and S, C
6
-C
14
-aryl, phenyl, naphthyl, fluorenyl and C
2
-C
13
-heteroaryl in which the number of heteroatoms selected from the group consisting of N, O and S may be 1-4.
The cyclic aliphatic or aromatic radicals are preferably 5- and 6-membered rings.
The abovementioned radicals may themselves each be monosubstituted or polysubstituted. These substituents may be, independently of one another, hydrogen, C
1
-C
20
-alkyl, C
2
-C
20
-alkenyl, C
1
-C
10
-haloalkyl, C
3
-C
8
-cycloalkyl, C
2
-C
9
-heterocycloalkyl, C
6
-C
10
-aryl, phenyl, naphthyl, fluorenyl, C
2
-C
6
-heteroaryl in which the number of heteroatoms, in particular from the group consisting of N, O and S, may be 1-4, C
1
-C
10
-alkoxy, preferably OMe, C
1
-C
9
-trihalomethylalkyl, preferably trifluoromethyl and trichloromethyl, halo, in particular fluoro and chloro, nitro, hydroxy, trifluoromethylsulfonato, oxo, amino, C
1
-C
8
-substituted amino of the formulae NH-alkyl-C
1
-C
8
, NH-aryl-C
5
-C
6
, N-alkyl
2
-C
1
-C
8
, N-aryl
2
-C
5
-C
6
, N-alkyl
3
-C
1
-C
8
+
, N-aryl
3
-C
5
-C
6
+
, NH—CO-alkyl-C
1
-C
8
, NH—CO-aryl-C
5
-C
6
, cyano, carboxylato of the formulae COOH and COOQ, where Q is either a monovalent cation or C
1
-C
8
-alkyl, C
1
-C
6
-acyloxy, sulfinato, sulfonato of the formulae SO
3
H and SO
3
Q, where Q is either a monovalent cation, C
1
-C
8
-alkyl or C
6
-aryl, phosphato of the formulae PO
3
H
2
, PO
3
HQ and PO
3
Q
2
, where Q is either a monovalent cation, C
1
-C
8
-alkyl or C
6
-aryl, tri-C
1
-C
6
-alkylsilyl, in particular SiMe
3
, and/or where two radicals R
1
or two radicals R
2
may be connected to one another, preferably forming a 4-8-membered ring which may be substituted by linear or branched C
1
-C
10
-alkyl, C
6
-aryl, benzyl, C
1
-C
10
-alkoxy, hydroxy or benzyloxy.
R3-R10 are each, independently of one another, a hydrogen atom or a radical selected from the group consisting of C
1
-C
24
-alkyl, C
1
-C
10
-haloalkyl, C
3
-C
8
-cycloalkyl, C
3
-C
8
-cycloalkenyl which may also contain 1-2 heteroatoms selected from the group consisting of N, O and S, C
6
-C
14
-aryl, phenyl, naphthyl, fluorenyl and C
2
-C
13
-heteroaryl in which the number of heteroatoms selected from the group consisting of N, O and S may be 1-4.
The cyclic aliphatic or aromatic radicals here are preferably 5- to 7-membered rings.
The abovementioned groups may themselves each be monosubstituted or polysubstituted. The substituents may be selected independently from the group consisting of hydrogen, C
1
-C
20
-alkyl, C
2
-C
20
-alkenyl, C
3
-C
8
-cycloalkyl, C
3
-C
8
-cycloalkenyl, C
2
-C
9
-heteroalkyl, C
1
-C
9
-heteroalkenyl, C
6
-C
10
-aryl, C,
1
-C
10
-haloalkyl, phenyl, naphthyl, fluorenyl, C
2
-C
6
-heteroaryl in which the number of heteroatoms, in particular from the group consisting of N, O and S, may be 1-4,
C
1
-C
10
-alkoxy, trichloromethyl, fluoro, oxo, amino, C
1
-C
8
-substituted amino of the formulae N-alkyl
2
-C
1
-C
8
, N-aryl
2
-C
5
-C
6
, N-alkyl
3
-C
1
-C
8
+, N-aryl
3
-C
5
-C
6
+
,
and where R5 and R6 may be connected so as to form a 5-7-membered cyclic aromatic or aliphatic compound.
P is trivalent phosphorus.
The invention also provides complexes comprising a chiral bidentate organophosphorus ligand of the formula (I) with at least one metal. Such complexes are obtainable by simple mixing of the organophosphorus compounds of the invention with metal complex precursors in solution.
It is preferred that
R1-R2,are each, independently of one another, a radical selected from the group consisting of C
1
-C
6
-alkyl, C
5
-C
6
-cycloalkyl, C
6
-aryl, phenyl, naphthyl, C
4
-C
5
-heteroaryl in which the number of heteroatoms selected from the group consisting of N, O and S is 1, where the abovementioned aromatic or heteroaromatic groups may themselves each be monosubstituted to trisubstituted. The substituents may be selected independently from the group consisting of hydrogen, C
1
-C
6
-alkyl, C
2
-C
4
-alkenyl, C
1
-C
6
-haloalkyl, C
2
-C
6
-heteroalkyl, C
6
-aryl, phenyl, naphthyl, fluorenyl, C
3
-C
5
-heteroaryl, in which the number of heteroatoms selected from the group

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