Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2001-02-20
2001-10-16
Trinh, Ba K. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S285000
Reexamination Certificate
active
06303796
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a novel organic compound which can be employed as a catalyst in an organic synthesis reaction, particularly in an asymmetric synthesis reaction, an optical resolution reaction, or an asymmetric recognition reaction.
BACKGROUND ART
Methods for synthesizing an optically active form of a chiral compound are roughly classified into the following three methods: (1) method in which an optically active compound is employed as a starting raw material; (2) method in which a racemic mixture is optically resolved; and (3) asymmetric synthesis method using an asymmetric catalyst.
In the method (2), a target compound is resolved as a diastereomer from a racemic mixture after formation of a salt by use of an optically active carboxylic acid or amine, or after esterification or amidation by use of an optically active carboxylic acid. Amines or carboxylic acids derived from natural products may be employed as a resolution reagent, but employment of such a reagent results in a low optical resolution yield of a racemic mixture. Therefore, in order to obtain a wider range of target compounds, a novel resolution agent must be provided.
In the method (3), a large quantity of optically active compounds can be synthesized by use of a catalytic amount of another optically active compound, and thus the method is most economical and effective. Enzymes derived from organisms or chemically synthesized catalysts may be employed as a catalyst for asymmetric synthesis. Of these, enzymes derived from organisms are chemically unstable and have disadvantageously high substrate specificity, and thus such enzymes are not generally employed. Meanwhile, few asymmetric catalysts are available that are easily synthesized and have high asymmetric yield and chemical yield, although a variety of chemically synthesized asymmetrical catalysts are available.
In view of the foregoing, an object of the present invention is to provide a compound which is easily synthesized and serves as an optical resolution agent that can attain a high optical resolution percentage, and a compound which is easily synthesized and serves as an asymmetric synthesis catalyst that can attain high asymmetric yield and chemical yield.
DISCLOSURE OF THE INVENTION
The present inventors have conducted extensive studies on a useful and novel optically active compound. As a result, the inventors have found that a particular &bgr;-diketone compound can serve as an optical resolution agent, and that a metal-coordinated &bgr;-diketone compound which is obtained by coordinating a particular &bgr;-diketone compound with a metal is effective as an asymmetric synthesis catalyst. The present invention has been accomplished on the basis of these findings.
Accordingly, a first aspect of the present invention is to provide a precursor of a &bgr;-diketone compound represented by the following formula (2):
[wherein X represents (CH
2
)
n
; n is an integer of 2-20; and the CH
2
of X may be replaced by an oxygen atom, a hetero ring, or an aromatic ring, but oxygen atoms are not sequentially arranged in X].
A second aspect of the present invention is to provide a &bgr;-diketone compound represented by the following formula (3):
[wherein X represents (CH
2
)
n
; n is an integer of 2-20; and the CH
2
of X may be replaced by an oxygen atom, a hetero ring, or an aromatic ring, but oxygen atoms are not sequentially arranged in X].
A third aspect of the present invention is to provide an optically active enantiomeric &bgr;-diketone compound represented by the following formula (3):
[wherein X represents (CH
2
)
n
; n is an integer of 7-11; and the CH
2
of X may be replaced by an oxygen atom, a hetero ring, or an aromatic ring, but oxygen atoms are not sequentially arranged in X].
A fourth aspect of the present invention is to provide an optical resolution agent comprising the &bgr;-diketone compound of the third aspect.
A fifth aspect of the present invention is to provide a metal-coordinated &bgr;-diketone compound in which a metal is coordinated with the &bgr;-diketone compound of the second or third aspect.
A sixth aspect of the present invention is to provide an organic synthesis method characterized in that a metal-coordinated &bgr;-diketone compound is prepared by coordinating a metal with the &bgr;-diketone compound of the second or third aspect, and the resultant metal-coordinated &bgr;-diketone compound is employed as a catalyst for an organic synthesis reaction, an asymmetric synthesis reaction, or an asymmetric recognition reaction.
A seventh aspect of the present invention is to provide a catalyst for an organic synthesis reaction, an asymmetric synthesis reaction, or an asymmetric recognition reaction, characterized by comprising the metal-coordinated &bgr;-diketone compound of the fifth aspect.
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will next be described in detail.
The compound of the present invention represented by the aforementioned formula (2) may be obtained by heating the &bgr;-diketone compound represented by the below-described formula (1) in toluene.
In this case, the &bgr;-diketone compound represented by the above formula (1) may be obtained, for example, through condensation between a dicarboxylic acid dichloride represented by the following formula (4) and Meldrum's acid represented by the following formula (5) in the presence of pyridine:
[wherein X represents (CH
2
)
n
; n is an integer of 2-20; and the CH
2
of X may be replaced by an oxygen atom, a hetero ring, or an aromatic ring, but oxygen atoms are not sequentially arranged in X].
The &bgr;-diketone compound of the present invention represented by the aforementioned formula (3) may be obtained at a high yield by heating the compound of the present invention represented by the aforementioned formula (2) at a very low concentration in boiling xylene or chlorobenzene.
In each of the formulas representing the compounds of the present invention, X is preferably (CH
2
)
n
. However, in consideration of the reaction mechanism, X may be any atomic groups that are thermally stable and do not react with ketene, such as o-, m-, or p-substituted benzene derivatives, naphthalene compounds, hetero rings, and ethers formed of ethylene glycol units. Therefore, in the formulas, X represents (CH
2
)
n
, n is an integer of 2-20, and the CH
2
of X may he replaced by an oxygen atom, a hetero ring, or an aromatic ring, but oxygen atoms are not sequentially arranged in X.
In accordance with the type or size of X of the &bgr;-diketone compound of the present invention represented by the formula (3), plane asymmetry may be generated due to the restricted rotation of a pyrrone ring, and the compound may be resolved into optically active enantiomers. Optical resolution of the compound is carried out by use of an optically active tertiary amine such as quinine, quinidine, cinchonine, cinchonidine, or sparteine. Alternatively, the compound may be reacted with an optically active primary amine to form enamine diastereomers, the diastereomers may be separated from each other through fractional recrystallization or column chromatography, and then each of the separated diastereomers may be hydrolyzed to remove an amine, to thereby obtain optically active enantiomers.
The compound of the present invention represented by the formula (3) is not limited to an optically active form, and functions as a bidentate ligand like acetylacetone. The compound may react with a variety of metals to form a complex, i.e., a metal-coordinated &bgr;-diketone compound, and the &bgr;-diketone compound may be employed as a catalyst for organic synthesis reactions. In addition, it is known that the &bgr;-diketone compound is useful as an intermediate for other large cyclic compounds, since a pyrrone ring of the compound may be opened or replaced by other rings (D. A. Barton and W. D. Ollis, Comprehensive Organic Chemistry, Vol. 4, Heterocyclic Compounds, Ed. by P. G. Sammes, Pergamon Press Ltd., Oxford, 1979, pp. 644-
Sato Masayuki
Yamaguchi Masahiko
Chisso Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
Trinh Ba K.
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