Bidentate organophosphorous ligands and their use

Details Bidentate organophosphorous ligands and their use Bidentate organophosphorous ligands and their use

2001-12-06

2003-06-03

Lambkin, Deborah C. (Department: 1626)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

06573389

ABSTRACT:

DESCRIPTION
Trisubstituted organophosphorus compounds are of great importance as ligands in homogeneous catalysis. Variation of the substituents on the phosphorus in such compounds enables the electronic and steric properties of the phosphorus ligand to be influenced in a targeted way, so that selectivity and activity in homogeneously catalyzed processes can be controlled. Enantiomerically enriched chiral ligands are used in asymmetric synthesis and asymmetric catalysis, and in this case it is important that the electronic properties and the stereochemical properties of the ligand are optimally matched to the respective catalysis problem. There is therefore a great need for chiral ligands which differ stereochemically and/or electronically in order to discover ligands which have been optimally “tailored” to a particular asymmetric catalytic reaction. In the ideal case, it is therefore desirable to have a chiral ligand framework which can be modified in a wide variety of ways and can be varied within a wide range in respect of its steric and electronic properties.
The structural variety of the phosphorus ligands known hitherto is very wide. These ligands can be classified, for example, according to classes of compounds, and examples of such classes of compounds are trialkylphosphines and triarylphosphines, phosphites, phosphinites, phosphonites, aminophosphines, etc. This classification according to classes of compounds is particularly useful for describing the electronic properties of the ligands.
Alternatively, phosphorus ligands can 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 (potential) stereoselectivity of metal complexes with phosphorus ligands as catalyst precursors/catalysts. Apart from the widespread C
2
-symmetric bidentate ligand systems such as DUPHOS, DIOP, BINAP or DEGUPHOS, unsymmetrical bidentate organophosphorus ligands are becoming increasingly significant in asymmetric catalysis. Important examples are the large class of versatile chiral ferrocenylphosphine ligands such as JOSIPHOS, for example, the aminophosphine-phosphinite ligands such as PINDOPHOS or DPAMPP which are used particularly successfully in the asymmetric hydrogenation of olefins, or phosphine-phosphite ligands such as BINAPHOS or BIPHEMPHOS, which represent milestones in the asymmetric hydroformylation of olefins. An important aspect of the success of these classes of compounds is ascribed to the creation of a particularly asymmetric environment of the metal center by means of these ligand systems. To utilize such an environment for effective transfer of the chirality, it is advantageous to control the flexibility of the ligand system as inherent limitation of the asymmetric induction.
The present invention describes novel, unsymmetrical, bidentate and chiral phosphorus ligand systems which in a unique way combine the above-described important features for effective asymmetric induction. They create both a highly asymmetric coordination sphere with organophosphorus donors which can be modified independently of one another, and they can be modified simply over an extraordinarily wide range in terms of their steric and electronic properties. Furthermore, they allow gradual adjustment of the rigidity by means of a change in the basic structure of the “ligand backbone”. At the same time, in contrast to many established ligand systems, the compounds of the invention can be obtained via simple syntheses over a wide range of variations.
The present invention relates to unsymmetric bidendate organophosphorus ligands of the formula (I) which have a modular structure and have a trivalent phosphine function and a second trivalent phosphorus group which is bound via a heteroatom to a chiral ligand framework,
R
1
R
2
PZC*HR
3
XP(YR
4
)(YR
5
)  (I)
where
R
1
-R
5
are identical or different and are each a hydrogen atom or a C
1
-C
50
group such as C
1
-C
24
-alkyl, C
2
-C
24
-alkenyl, C
3
-C
8
-cycloalkyl, C
3
-C
8
-cycloalkenyl, C
6
-C
14
-aryl, phenyl, naphthyl, fluorenyl, C
2
-C
13
-heteroaryl in which the number of heteroatoms, in particular from the group consisting of N, O, S, can be 1-4, where the cyclic aliphatic or aromatic radicals are preferably 5- to 7-membered rings and the specified substituents can each bear one or more substituents selected independently from the group consisting of hydrogen, C
1
-C
20
-alkyl, C
2
-C
20
-alkenyl, C
1
-C
10
-haloalkyl, C
3
-C
8
-cyclo-alkyl, C
3
-C
8
-cycloalkenyl, C
2
-C
8
-heteroalkyl, C
1
-C
9
-heteroalkenyl, C
6
-C
14
-aryl, phenyl, naphthyl, fluorenyl, C
2
-C
7
-heteroaryl in which the number of heteroatoms, in particular from the group consisting of N, O, S, can be 1-4, C
1
-C
10
-alkoxy, C
1
-C
9
-trihalomethylalkyl, trifluoromethyl, trichloromethyl, fluoro, chloro, bromo, iodo, nitro, hydroxy, trifluoromethylsulfonato, oxo, thio, thiolato, amino, C
1
-C
8
-substituted amino of the forms mono-, di-, tri-C
1
-C
8
-alkylamino or C
2
-C
8
-alkenylamino or mono-, di-, tri- C
6
-C
8
-arylamino or C
1
-C
8
-alkyl-C
6
-C
8
-arylamino, cyano, carboxyl, carboxylato of the formula COOR
8
, where R
8
is a monovalent cation or a C
1
-C
8
-alkyl group, C
1
-C
8
-acyloxy, sulfinato, sulfonato of the formula SO
3
R
8
, phosphato of the formula PO
3
H
2
, PO
3
HR
8
, PO
3
R
8
2
, tri-C
1
-C
6
-alkylsilyl, and where two of the substituents can also be bridged and R
1
and R
2
or R
4
and R
5
can be joined to one another so as to form a 4-8-membered cyclic compound,
X is —O—, —S— or —NR
5
—,
R
6
is a radical as defined for R
1
-R
5
,
Y is a direct phosphorus-carbon bond, —O— or —NR
7
—, where
R
7
is a radical as defined for R
1
-R
5
,
Z represents one to six carbon atoms which are joined by single or double bonds and link the phosphine unit PR
1
R
2
to the carbon center C*, where Z is part of an aliphatic, cycloaliphatic, olefinic, cycloolefinic system which may contain heteroatoms, preferably nitrogen, oxygen or sulfur, a metallocene, in particular 1,1′- or 1,2-disubstituted ferrocene, or particularly preferably an aromatic or heteroaromatic ring system which may be unsubstituted or be substituted by one or more substituents as indicated for R
1
-R
5
or directly substituted by C
1
-C
10
-alkoxy, C
1
-C
9
-trihalomethylalkyl, trifluoromethyl, trichloromethyl, fluoro, chloro, bromo, iodo, nitro, hydroxy, trifluoromethylsulfonato, oxo, thio, thiolato, amino, C
1
-C
8
-substituted amino of the formulae NH
2
, NH-alkyl-C
1
-C
8
, NH-aryl-C
5
-C
6
, N-(alkyl-C
1
-C
8
)
2
, N-(aryl-C
5
-C
6
)
2
, N-(alkyl-C
1
-C
8
)
3
+
, N-(aryl-C
5
-C
6
)
3
+
, cyano, carboxylato of the formulae COOH and COOR
8
, where R
8
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
R
8
, where R
8
is either a monovalent cation, C
1
-C
8
-alkyl or C
6
-aryl, phosphonato, phosphato of the formulae PO
3
H
2
, PO
3
HR
8
and PO
3
R
8
2
, where R
8
is either a monovalent cation, C
1
-C
8
-alkyl or C
6
-aryl, C
1
-C
6
-trialkylsilyl, CONH
2
, NHCO-alkyl-C
1
-C
4
, CON(alkyl-C
1
-C
8
)
2
, CO-alkyl-C
1
-C
8
, COO-alkyl-C
1
-C
8
, CO-alkenyl-C
1
-C
8
, NHCOO-alkyl-C
1
-C
4
, CO-aryl-C
6
-C
10
, COO-aryl-C
6
-C
10
, CHCH—COO-alkyl-C
1
-C
8
, CHCHCOOH and
P is trivalent phosphorus.
The invention also relates to complexes comprising such a chiral ligand system of the formula (I) with at least one metal.
R
1
-R
5
are each preferably, independently of one another, a C
1
-C
20
-alkyl, alkenyl, haloalkyl, cycloalkyl, cycloalkenyl, aryl, heteroaryl radical, each of which may be substituted by one or more substituents selected from the group consisting of C
1
-C
20
-alkyl, C
2
-C
20
-alkenyl, C
1
-C
10
-haloalkyl, C
3
-C
8
-cycloalkyl, C
3
-C
8
-cycloalkenyl, C
6
-C
14
-aryl, C
2
-C
7
-heteroaryl, C
1
-C
10
-alkoxy, halo, nitro, hydroxy, oxo, thio, thiolato, amino, substituted amino, cyano, sulfonato, tri-C
1
-C
6
-alkylsilyl, where two of the substituents may also be bridged.

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