Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2001-02-21
2004-01-20
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S160000, C502S171000, C502S172000
Reexamination Certificate
active
06680275
ABSTRACT:
The present invention relates to a catalyst for asymmetric epoxidation of enones and a process for producing an optically active epoxide employing it.
As a reaction for asymmetric epoxidation of enones, a method has been known wherein a compound having a carbon—carbon double bond conjugated to a carbonyl group, such as chalcone, is asymmetrically epoxidized with a hydroxyperoxide compound in the presence of a complex catalyst prepared from an optically active dihydroxy compound and a rare earth metal alkoxide.
Specifically, it is known to use a tetrahydrofuran solution of (R)-binaphthol and lanthanum triisopropoxide, as a (R)-lanthanum binaphthoxide, for the asymmetric epoxidation reaction (JP-A-10-120668).
However, by the method disclosed in JP-A-10-120668, if, for example, tert-butyl hydroperoxide (hereinafter referred to simply as TBHP) is used as an oxidizing agent, the desired optically active epoxide is obtainable only in a low yield and with a low optical purity. Therefore, in order to obtain a satisfactory result, it has been required to use a special binaphthol having methylol introduced at the 3-position, or to use an alkoxide of a rare earth metal other than lanthanum, such as ytterbium. Further, the amount of the catalyst is required to be from 5 to 10 mol % relative to the enone subjected to the reaction, and reduction of the amount of the catalyst has been desired.
The present applicants have already filed a patent application (JP-10-192743) for a catalyst composition comprising (A) an optically active binaphthol, (B) lanthanum triisopropoxide, (C) triphenylphosphine oxide, etc., which has a higher reactivity than the above-mentioned conventional catalyst and which presents a high optical purity to the product.
The present inventors have conducted a further study on a catalyst which presents a high optical activity and as a result, have found that a complex catalyst comprising (A) an optically active binaphthol, (B) lanthanum triisopropoxide, (C) triphenylphosphine oxide and (D) cumene hydroperoxide or tert-butyl hydroperoxide, is a catalyst which presents a higher optical activity to the product.
Further, the present inventors have conducted an extensive study to develop a catalyst which has a high reactivity and which presents a high optical purity and have found that a catalyst composition comprising (A) an optically active binaphthol, (B) lanthanum triisopropoxide and (c) tri(4-fluorophenyl)phosphine oxide, tri(4-chlorophenyl)phosphine oxide or tri(4-trifluoromethylphenyl)phosphine oxide, has a high reactivity and high stability as compared with the conventional catalyst and presents a high optical purity to the product, and further, it is thereby possible to reduce the amount of the catalyst relative to the enone subjected to the reaction. The present invention has been accomplished on the basis of these discoveries.
Namely, the present invention provides a complex catalyst for asymmetric epoxidation of enones, which comprises:
(A) an optically active binaphthol,
(B) lanthanum triisopropoxide,
(C) triphenylphosphine oxide, and
(D) cumene hydroperoxide or tert-butyl hydroperoxide;
a catalyst for asymmetric epoxidation of enones, which comprises:
(A) an optically active binaphthol,
(B) lanthanum triisopropoxide, and
(c) tri(4-fluorophenyl)phosphine oxide, tri(4-chlorophenyl)phosphine oxide or tri(4-trifluoromethylphenyl)phosphine oxide; and a process for producing an optically active epoxide of the following formula (1):
wherein each of R
1
and R
2
which are independent of each other, is a C
1-20
linear, branched or cyclic alkyl group, an aromatic group, an aromatic group substituted by from 1 to 5 C
1-5
alkyl groups, an aromatic group substituted by from 1 to 5 C
1-5
alkoxy groups, an aromatic group substituted by from 1 to 5 halogen atoms, a C
1-5
linear, branched or cyclic alkyl group substituted by an aromatic group, or a C
1-5
linear, branched or cyclic alkyl group substituted by a halogenated aromatic group, and symbol * represents optically active carbon, which comprises reacting an enone of the following formula (2):
wherein R
1
and R
2
are as defined above, with an oxidizing agent in the presence of a such a catalyst.
Now, the present invention will be described in detail with reference to the preferred embodiments.
Firstly, the complex catalyst comprising (A) an optically active binaphthol, (B) lanthanum triisopropoxide, (C) triphenylphosphine oxide and (D) tert-butyl hydroperoxide or cumene hydroperoxide, will be described.
In the present invention, the constituting proportions of the above catalyst components are not particularly limited. However, (A) the binaphthol is usually from 1 to 3 mols, (C) the triphenylphosphine oxide is usually from 0.1 to 10 mols, preferably from 1 to 10 mols, and (D) the tert-butyl hydroperoxide or cumene hydroperoxide is usually from 1 to 20 mols, preferably from 1 to 10 mols, per mol of (B) the lanthanum triisopropoxide.
The above-mentioned components constituting the catalyst are added to a solvent which will be described hereinafter and maintained for from 0.5 to 4 hours within a range of from −50 to 100° C., whereby a complex will be formed. By the formation of the complex, the solution will have a color of yellowish green to deep green.
In the present invention, it is preferred that a solution of the above catalyst complex is preliminarily prepared in the reaction system, and then the substrate to be subjected to the reaction and a necessary amount of an oxidizing agent are added to carry out the reaction.
In a case where the preparation of a solution of the catalyst complex of the present invention is not carried out, for example, in a case where (A) the optically active binaphthol, (B) the lanthanum triisopropoxide and (C) the triphenylphosphine oxide are mixed in a solvent without adding (D) the tert-butyl hydroperoxide or cumene hydroperoxide, and then the substrate to be subjected to the reaction and (D) the tert-butyl hydroperoxide or cumene peroxide are all together added to the system to carry out the reaction, it is likely that the yield will decrease, and the optical purity will decrease.
Now, the catalyst comprising (A) an optically active binaphthol, (B) lanthanum triisopropoxide and (c) tri(4-fluorophenyl)phosphine oxide, tri(4-chlorophenyl)phosphine oxide or tri(4-trifluoromethylphenyl)phosphine oxide, will be described.
In the present invention, the optically active binaphthol is specifically (R)-(+)-1,1′-bi-2-naphthol (hereinafter referred to as (R)-binaphthol) or (S)-(−)-1,1′-bi-2-naphthol (hereinafter referred to as (S)-binaphthol).
In the present invention, the constituting proportions of the above catalyst components are not particularly limited. However, (A) the binaphthol is usually from 1 to 3 mols, and (c) the tri(4-fluorophenyl) phosphine oxide, tri(4-chlorophenyl)phosphine oxide or tri(4-trifluoromethylphenyl)phosphine oxide, is usually from 0.1 to 10 mols, preferably from 1 to 10 mols, per mol of (B) the lanthanum triisopropoxide.
In the present invention, to the above catalyst, a predetermined amount of cumene peroxide (hereinafter sometimes referred to as CMHP) or tert-butyl hydroperoxide (hereinafter sometimes referred to as TBHP) may be added to form a complex showing a yellowish green to deep green color as a reactive species, and the mixture may be used for the reaction. However, in such a case, there is no substantial difference in the obtainable results. Further, to the above catalyst, CMHP or TBHP required for the reaction is preliminarily added, and then the enone may be added to carry out the reaction. However, also in this case, there is no substantial difference in the obtainable results.
In the present invention, the above-mentioned components constituting the catalyst may be added to a solvent which will be described hereinafter and maintained for from 0.5 to 4 hours within a range of from −50° C. to 100° C. to form a complex and then the substrate to be subjected to the reaction and an oxidizing agent may be added to carry ou
Inanaga Junji
Kagawa Takumi
Bell Mark L.
Nixon & Vanderhye P.C.
Pasterczyk J.
Tosoh Corporation
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