Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-08-20
2001-12-04
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S320000, C568S335000, C568S626000, C568S628000, C568S662000, C568S663000, C556S465000, C556S482000
Reexamination Certificate
active
06326520
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to optically active compounds, which are useful as intermediates for producing medicines, agricultural chemicals and various functional materials, and methods for producing such optically active compounds.
Japanese Patent First Provisional Publication JP-A-11-189550 discloses a method for producing an optically active Friedel-Crafts-type compound by reacting an aromatic compound (e.g., anisole) with a halogenated acetaldehyde in the presence of an optically active binaphthol-titanium complex used as a catalyst.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel optically active compound.
It is another object of the present invention to provide a method for easily producing such compound.
According to a first aspect of the present invention, there is provided a first method for producing an optically active compound represented by the general formula [IV]. This method comprises reacting a compound represented by the general formula [II] with a halogenated acetaldehyde represented by the general formula [III], in the presence of an optically active binaphthol-titanium complex,
where R is a lower alkyl group or —Si(R
3
)
3
, where R
3
is a lower alkyl group and three of R
3
may be the same or different groups, R
1
is a lower alkyl group or a substituted or unsubstituted phenyl group, R
2
is hydrogen atom or a lower alkyl group or a substituted or unsubstituted phenyl group, or R
1
and R
2
are combined to form an alkylene group, and X is hydrogen, fluorine, chlorine or bromine with a proviso that three of said X may be the same or different atoms, but are not hydrogen at the same time. In the general formula [IV] and the other formulas throughout the application, * mark represents an asymmetric carbon atom.
According to a second aspect of the present invention, there is provided a second method for producing an optically active, &agr;,&bgr;-dihydroxyketone represented by the general formula [V]. This method comprises oxidizing a compound represented by the general formula [IV] into the optically active &agr;,&bgr;-dihydroxyketone,
where R, R
1
, R
2
and X are defined as above.
The above-mentioned optically active compounds represented by the general formulas [IV] of the first method and the optically active &agr;,&bgr;-dihydroxyketone represented by the general formula [V] of the second method can each be used as intermediates for producing medicines, agricultural chemicals, various functional materials, etc. These aimed compounds with high optical purity can each be produced easily by the above-mentioned first and second methods.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The above-mentioned optically active binaphthol-titanium complex is used as a catalyst in the first method. This complex may have a structure represented by the following general formula [I], but is not limited to this structure.
where X and X′ are as a whole a group represented by the following formula or are each halogen atom, OTf, N(Tf)
2
or C(Tf)
3
where Tf represents —SO
2
Rf where Rf is fluorine atom or a lower perfluoroalkyl group,
where each of Y and Y′ is hydrogen atom, halogen atom, a lower alkyl group, CN, Si(R
5
)
3
, SO
2
R
6
, or —C≡CR
7
, where R
5
is a lower alkyl group, R
6
is a lower alkyl group or a substituted or unsubstituted phenyl group, and R
7
is hydrogen atom, a lower alkyl group, a substituted or unsubstituted phenyl group, or Si(R
8
)
3
where R
8
is a lower alkyl group.
The optically active binaphthol-titanium complex used in the first method is preferably one prepared by a third method comprising the step of reacting a titanium-containing reactant with a binaphthol represented by the following general formula,
where Y, Y′ R
5
, R
6
, R
7
and R
8
are defined as above. Upon this, the molar ratio of titanium to the binaphthol is preferably from 1/10 to 1/1, more preferably from 1/2 to 1/1. It is preferable that the titanium-containing reactant is (1) a reaction liquid obtained by reacting a tetrahalogenotitanium, of which halogens are fluorine, chlorine, bromine and/or iodine, with a lower alcohol or a titanium tetraalkoxide of lower alcohol, or (2) a titanium halogenoalkoxide of lower alcohol, for example, dialkoxydihalogenotitanium or diisopropoxydihalogenotitanium, of which halogens are flourine, chlorine, bromine and/or iodine. Examples of this lower alcohol are methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol. Of these, isopropanol is the most preferable. The step of the third method for preparing the complex is conducted preferably in a solvent in the presence of a zeolite. This zeolite may be selected from various synthetic zeolites. Of these, it is preferable to select one from A-type zeolites, such as 3A, 4A and 5A, and X-type zeolites, such as 13X. The solvent used in the third method is not particularly limited, and can be selected from halogenated hydrocarbons such as methylene chloride, chloroform, carbon tetrachloride and dichloroethane; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; ethers such as dimethyl ether, diethyl ether, tetrahydrofuran and diglyme; and nitriles such as acetonitrile and propionitrile.
For example, the third method for preparing an optically active binaphthol-titanium complex may be conducted as follows. At first, a dialkoxydihalogenotitanium is prepared by reacting at least one tetrahalogenotitanium (e.g., tetrafluorotitanium, tetrachlorotitanium, tetrabromotitanium and/or tetraiodotitanium) with tetraisopropoxytitanium in methylene chloride (solvent). Then, the complex is prepared by reacting this dialkoxydihalogenotitanium with an optically active binaphthol in the presence of a zeolite, molecular sieve (MS) 4A. Optically active binaphthol (BINOL) has two types, that is, one type of S-configuration ((S)-BINOL) and another type of R-configuration ((R)-BINOL). Thus, the obtained complex also has one type of S-configuration and another type of R-configuration. One of these two types of the complex can be chosen according to the absolute configuration of the aimed product of the first method.
Nonlimitative examples of the halogenated acetaldehyde represented by the general formula [III] are trifluoroacetaldehyde (fluoral), chlorodifluoroacetaldehyde, bromodifluoroacetaldehyde, dichlorofluoroacetaldehyde, bromochlorofluoroacetaldehyde, dibromofluoroacetaldehyde, trichloroacetaldehyde, bromodichloroacetaldehyde, dibromochloroacetaldehyde, tribromoacetaldehyde, difluoroacetaldehyde, chlorofluoroacetaldehyde, bromofluoroacetaldehyde, dichloroacetoaldehyde, bromochloroacetaldehyde, dibromoacetaldehyde, fluoroacetaldehyde, chloroacetaldehyde, and bromoacetaldehyde. In the invention, these halogenated acetaldehydes may be replaced with their hydrates or hemiacetals.
The reaction of the first method is an equimolar Friedel-Crafts reaction. Therefore, it is preferable to use the halogenated acetaldehyde in an amount of at least 1 mole, more preferably of 1-100 moles, still more preferably of 1-10 moles, per mole of the compound represented by the general formula [II].
In the first method, the amount of the optically active binaphthol-titanium complex, which is used as an asymmetric catalyst, is not particularly limited. Its amount is preferably 0.1-50 mol %, more preferably 0.1-30 mol %, still more preferably 0.1-10 mol %, based on the total moles of the compound represented by the general formula [II].
Although solvent may not be used in the reaction of the first method, it is preferably used therein. Examples of this solvent are halogenated hydrocarbons such as methylene chloride, chloroform, and carbon tetrachloride; aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; ethers such as tetrahydrofuran, diethyl ether, and dioxane; and esters such as ethyl acetate. The reaction of the first method is conducted at a temperature o
Ishii Akihiro
Mikami Koichi
Central Glass Company Limited
Crowell & Moring LLP
Padmanabhan Sreeni
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