Polymeric diphosphine ligands for homogeneously soluble...

Details Polymeric diphosphine ligands for homogeneously soluble... Polymeric diphosphine ligands for homogeneously soluble...

2001-01-24

2003-09-23

Moore, Margaret G. (Department: 1712)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C502S158000, C502S159000, C502S162000, C525S123000, C525S130000, C525S188000, C528S030000, C528S072000

Reexamination Certificate

active

06624248

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to molecular weight-enlarged ligands for catalysts for the asymmetric, homogeneous hydrogenation of double bonds.
2. Discussion of the Background
Catalytically active species for asymmetric, homogenous hydrogenation of double bonds are extremely advantageous for the industrial synthesis of organic substances. This is particularly the case due to their improved recyclability, which helps keep manufacturing costs low.
Molecular weight-enlarged catalysts for homogeneous enantioselective hydrogenation have been previously disclosed. J. Am. Chem. Soc. 1998, 120, 9481 et seq. addresses the problem of producing soluble molecular weight enlargements, inter alia for hydrogenation catalysts. Wandrey et al. have also reported the use of a molecular weight-enlarged hydrogenation catalyst in a membrane reactor (Angew. Chem. 1990, 102, 445 et seq.). U.S. Pat. No. 5,777,062 describes homogeneously soluble polymer-enlarged ligands for hydrogenation catalysts. The monomeric ligands are bound in that case to the polymer backbone through urethane or urea linkers.
The problems associated with the use of such catalysts have not been previously adequately resolved. Accordingly, there is still a need for novel catalyst systems which make it possible to perform continuous processes catalytically. The problems that must be addressed relate, for example, to the separability of the product from the catalyst with regard to the membrane used and to inactivation of the catalyst over time.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a homogenous soluble hydrogenation catalyst that is readily separable from the product of hydrogenation.
A further object of the present invention is to provide a homogenous soluble hydrogenation catalyst having improved lifetime.
A further object of the present invention is to provide a molecular weight increased ligand for preparing such a hydrogenation catalyst.
Another object of the present invention is to provide a method for the production of such ligands and catalysts.
Another object of the present invention is to provide a method for asymmetric, homogenous hydrogenation of double bond containing compounds using the catalysts.
These and other objects of the present invention have been satisfied by the discovery of a ligand comprising a molecular weight-enlarged, homogeneously soluble ligand having an average molecular weight in the range from 1,000-1,000,000 g/mol comprising a molecular weight enlarging polymer and one or more ligands, wherein said one or more ligands are homochiral active centers of bis(3,4-diarylphosphinyl)pyrrolidine, wherein said one or more ligands are bound to said molecular weight enlarging polymer via a linker selected from the group consisting of formulae a)-g)
a)
—Si(R
2
)—;
b)
—(SiR
2
—O)
n
—
n = 1-10000;
c)
—(CHR—CHR—O)
n
—
n = 1-10000;
d)
—(X)
n
—
n = 1-20;
e)
Z—(X)
n
—
n = 0-20;
f)
—(X)
n
—W
n = 0-20;
g)
Z—(X)
n
—W
n = 0-20;
wherein
R represents H, (C
1
-C
8
) alkyl, (C
6
-C
18
) aryl, (C
7
-C
19
) aralkyl, or ((C
1
-C
8
) alkyl)
1-3
-(C
6
-C
18
) aryl;
X represents (C
6
-C
18
) arylene, (C
1
-C
8
) alkylene, (C
1
-C
8
) alkenylene, ((C
1
-C
8
) alkyl)
1-3
-(C
6
-C
18
) arylene, or (C
7
-C
19
) aralkylene;
Z represents C(═O)O—, C(═O)NH—, C(═O)—, NR, O, CHR, CH
2
, C═S, S, PR, wherein Z is further bound directly to said molecular weight enlarging polymer; and
W represents C(═O)O—, C(═O)NH—, C(═O)—, NR, O, CHR, CH
2
, C═S, S, PR, wherein W is further bound directly to said ligand;
or said one or more ligands are bound directly to said molecular weight-enlarging polymer, its use in preparing a catalyst and the catalyst prepared thereby, as well as the use of the catalyst in a method for the production of enantimerically enriched organic compounds.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to a molecular weight-enlarged, homogeneously soluble ligand having an average molecular weight of 1,000-1,000,000 g/mol which comprises a molecular weight enlarging polymer and one or more ligands, wherein the one or more ligands are homochiral active centers of bis(3,4-diarylphosphinyl)pyrrolidines, wherein these ligands are bound to said polymer via a linker selected from the group consisting of formulae a)-g):
a)
—Si(R
2
)—;
b)
—(SiR
2
—O)
n
—
n = 1-10000;
c)
—(CHR—CHR—O)
n
—
n = 1-10000;
d)
—(X)
n
—
n = 1-20;
e)
Z—(X)
n
—
n = 0-20;
f)
—(X)
n
—W
n = 0-20;
g)
Z—(X)
n
—W
n = 0-20;
wherein
R is H, (C
1
-C
8
) alkyl, (C
6
-C
18
) aryl, (C
7
-C
19
) aralkyl, ((C
1
-C
8
) alkyl)
1-3
-(C
6
-C
18
) aryl,
X is (C
6
-C
18
) arylene, (C
1
-C
8
) alkylene, (C
1
-C
8
) alkenylene, ((C
1
-C
8
) alkyl)
1-3
-(C
6
-C
18
) arylene, (C
7
-C
19
) aralkylene,
Z represents on the polymer side C(═O)O—, C(═O)NH—, C(═O)—, NR, O, CHR, CH
2
, C═S, S, PR,
W represents on the ligand side C(═O)O—, C(═O)NH—, C(═O)—, NR, O, CHR, CH
2
, C═S, S, PR,
or the active centers are bound directly to the molecular weight-enlarging polymer, and to the polymer-enlarged hydrogenation catalysts formed using these ligands. These catalysts are useful in industrial organic synthesis, and are very readily recyclable.
For the purposes of the present invention, the molecular weight enlarging polymer can be freely selected. The enlargement is limited, on the one hand, by considerations of practicability and cost and, on the other, by technical issues (retention capacity, solubility etc.). Some molecular weight enlarging polymers for catalysts are described in Reetz et al., Angew. Chem. 1997, 109, 1559 et seq.; Seebach et al., Helv. Chim Acta 1996, 79, 1710 et seq.; Kragl et al., Angew. Chem. 1996, 108, 684 et seq.; Schurig et al., Chem. Ber./Recueil 1997, 130, 879 et seq.; Bolm et al., Angew. Chem. 1997, 109, 773 et seq.; Bolm et al. Eur. J. Org. Chem. 1998, 21 et seq.; Baystone et al. in Speciality Chemicals 224 et seq.; Salvadori et al., Tetrahedron: Asymmetry 1998, 9, 1479; Wandrey et al., Tetrahedron: Asymmetry 1997, 8, 1529 et seq.; ibid. 1997, 8, 1975 et seq.; Togni et al. J. Am. Chem. Soc. 1998, 120, 10274 et seq., Salvadori et al., Tetrahedron Lett. 1996, 37, 3375 et seq.; WO 98/22415; and in particular DE 19910691.6, the relevant contents of each of which are hereby incorporated by reference.
Preferred molecular weight-enlarging polymers for binding the ligands are polyacrylates, polyvinylpyrrolidinones, polysiloxanes, polybutadienes, polyisoprenes, polyalkanes, polystyrenes, polyoxazolines or polyethers (PEG, PEP) or mixtures thereof. For the purposes of the present invention, mixtures are taken to mean the fact that individual monomers or polymers of differing origin are polymerised together to yield block copolymers, graft copolymers, random copolymers or even intimate mixtures of two or more polymers (i.e. polymer blends).
Polyacrylates, polystyrenes, polysiloxanes, polyethers and mixtures thereof are particularly preferred for this purpose.
The following structures are extremely preferred, wherein, on a statistical average, the values for a should be 1 and for b 10-30, preferably 20 (scheme 1).
The molecular weight-enlarging polymers preferably exhibit an average molecular weight in the range from 5,000-500,000, particularly preferably from 5,000-300,000 g/mol. The present invention also provides a process for the production of a ligand according to the present invention, wherein the process comprises one of the following steps A)-C):
A) binding a ligand having a catalytically active center to a monomer directly or through a linker to provide a ligand modified monomer, then polymerizing said ligand modified monomer in the presence of one or more unmodified monomers;
B) binding a ligand having a catalytically active center to a polymer, either directly or through a linker;
C) following either step A) or B) and further copolymerizing the resulting polymer with one or mor

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