Phosphine derivative and polymer thereof and transition...

Details Phosphine derivative and polymer thereof and transition... Phosphine derivative and polymer thereof and transition...

2000-03-30

2002-10-15

Wu, David W. (Department: 1713)

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

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S240000, C526S347000, C526S340000

Reexamination Certificate

active

06465594

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a phosphine derivative, a polymer comprising the phosphine derivative, a transition metal complex comprising the phosphine derivative or a polymer thereof, and a process for producing an optically active compound by asymmetric hydrogenation using the transition metal complex as a catalyst.
BACKGROUND OF THE INVENTION
A large number of transition metal complexes have been used in catalyst systems for organic syntheses. In particular, noble metal complexes, though expensive, have enjoyed wide use for their stability and ease of handling. Extensive study has been given to use of transition metal complexes, such as nobel metal complexes, as a catalyst in various syntheses, and we can find many reports on the transition metal complexes which have effected organic synthesis reactions, inclusive of asymmetric reactions, that had been regarded as impossible with traditional means.
Optically active ligands useful in asymmetric catalytic reactions include various types. Taking note of asymmetric hydrogenation using a transition metal-phosphine complex, 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (hereinafter referred to as BINAP) is among the optically active ligands having the most excellent ability of asymmetric recognition. There are many reports on hydrogenation reaction of olefins or ketone compounds using a Rh or Ru complex comprising BINAP as a ligand (see, for example, Ryoji Noyori,
Asymmetric Catalysis in Organic Synthesis
, pp. 16-85, A Wiley-Interscience Publication (1994)).
However, these expensive noble metal catalysts cannot be recovered, or their recovery requires complicated operation involving a heavy loss. In addition, it is impossible or uneconomical to reuse the recovered catalyst. It has therefore been demanded to develop a catalyst which can easily be separated and reused and maintains its activity and selectivity even in repeated use.
Application of synthetic chiral polymers as a medium for resolution of a racemate, a reagent or a catalyst for asymmetric synthesis, and the like has been studied extensively. Studies on the ability of chiral polymers in asymmetric recognition have recently made remarkable advances. In particular, when applied to stereoselective organic reactions, chiral polymers provide a specific reaction site different from general homogeneous reaction systems. Use of a polymeric reagent or a polymeric catalyst in organic synthesis is advantageous for improving industrial processes in that the product can be separated easily and that the reagent or catalyst can be reused.
Applications of the chiral polymers to stereoselective organic syntheses include the following examples.
1) An optically active amino acid is allowed to react with 4-vinylbenzenesulfonyl chloride to obtain a chiral monomer (C), which is copolymerized with styrene and divinylbenzene to obtain a polymer having the following structural units:
The resulting polymer ligand and diborane are allowed to react with each other to prepare chiral polymer-bound oxabororidinonone, which is used as a Lewis acid catalyst for Diels-Alder reaction between cyclopentadiene and metacrolein (S. Itsuno, et al.,
Tetrahedron: Asymmetry
, vol. 6, p. 2547 (1995)).
2) A polymer of a manganese-salen complex (D) is used in asymmetric epoxidation of olefins (S. Sivaram, et al.,
Tetrahedron: Asymmetry
, vol. 6, p. 2105 (1995)).
3) 2-p-Styryl-4,5-bis[(dibenzophosphoryl)methyl]-1,3-dioxolane (E), styrene, and divinylbenzene are copolymerized to obtain a chiral polymer having the following structural units:
Platinum chloride is coordinated to the resulting polymer ligand to obtain a chiral polymer catalyst. Styrene is hydroformylated by using the resulting polymer catalyst in the copresence of tin chloride (J. K. Stille, et al.,
J. Org. Chem
., vol. 51, p. 4189 (1986)).
However, any of these known polymeric catalysts has not been put to practical use due to insufficient catalytic activity or a lower reaction yield than reached by using the corresponding monomer.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polymer-bearing ligand making a catalyst for asymmetric synthesis reactions which exhibits satisfactory performance in catalytic activity, optical purity, and the like.
The present inventors synthesized a monomer having a binaphthyl skeleton with a diarylphosphino group at the 2,2′-positions and a vinyl group at the 6-position and prepared a copolymer comprising the monomer, a styrene derivative, and divinylbenzene. They have found the resulting polymer excellent as a ligand of a catalyst for asymmetric hydrogenation reaction.
The invention provides a phosphine derivative represented by formula (I):
wherein Ar represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group.
The invention also provides an oligomer or polymer comprising a structural unit represented by formula (III):
wherein Ar is as defined above; and k represents an integer of 2 to 100.
The invention further provides a transition metal complex obtained by allowing a transition metal compound to react on the compound represented by formula (I) or the oligomer or polymer having the structural unit of formula (III).
The invention furthermore provides a process for producing an optically active amino acid compound represented by formula (B):
wherein R
3
represents a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; R
4
represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyl group; R
5
represents a hydrogen atom, an alkyl group, an alkoxy group, a substituted or unsubstituted aryl group or a substituted or unsubstituted aralkyloxy group; and * indicates an asymmetric carbon atom, which comprises asymmetrically hydrogenating a dehydroamino acid compound represented by formula (A):
wherein R
3
, R
4
, and R
5
are as defined above, in the presence of the above-described transition metal complex.
DETAILED DESCRIPTION OF THE INVENTION
In formula (I), Ar represents a substituted or unsubstituted phenyl group or a substituted or unsubstituted naphthyl group. The substituents that may be on the phenyl or naphthyl group include a lower alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl or isobutyl; a halogen atom, such as fluorine, chlorine or bromine; a lower alkoxy group, such as methoxy, ethoxy, propoxy or butoxy; a halogenated lower alkyl group, such as trifluoromethyl or trichloromethyl; and a benzyloxy group. Ar preferably represents phenyl, 4-tolyl, 4-methoxyphenyl, 3,5-xylyl, and naphthyl groups.
The compound (I) of the invention can be prepared through, for example, the following reaction scheme, in which a phenyl group is taken as an example of Ar:
Optically active binaphthol (VII) and trifluoromethanesulfonic acid anhydride (Tf
2
O) are allowed to react in methylene chloride in the presence of pyridine to obtain 2,2′-bis(trifluoromethanesulfonyloxy)-1,1′-binaphthalene (VIII) in accordance with the method taught in the literature (M. Vondenhof and J. Mattay,
Tetrahedron Lett
., vol. 31, pp. 985-988 (1990), L. Kurz, et al.,
Tetrahedron Lett
., vol. 31, pp. 6321-6324 (1990), and Y. Uozumi, et al.,
J. Org. Chem
., vol. 58, pp. 1945-1948 (1993)). The compound (VIII) is allowed to react with diphenylphosphine oxide (Ph
2
PHO) in the presence of a catalytic amount of a palladium-phosphine complex to obtain 2′-diphenylphosphinyl-2-trifluoromethanesulfonyloxy-1,1′-binaphthalene (IX), which is then hydrolyzed with lithium hydroxide (LiOH) to form 2′-diphenylphosphinyl-2-hydroxy-1,1′-binaphthalene (X). The compound (X) is brominated in dioxane to give 2′-diphenylphosphinyl-2-hydroxy-6-bromo-1,1′-binaphthalene (XI). The compound (XI) is reduced with trichlorosilane (HSiCl
3
) in the presence of an amine to obtain 2′-diphenylphosphino-2-hydroxy-6-bromo-1,1′-binaphthalene (XII). Th

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