Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1999-08-03
2001-05-29
Lee, Howard C. (Department: 1623)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06239316
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
The present invention relates to a novel optically active secondary alcohol having a methyl group on an asymmetric carbon and an alkoxy terminal having branched alkyl chains formed of the same numbers of carbon atoms and a process for the production thereof.
2. Prior Art
While optically active compounds have been used in the fields of medicaments and agricultural chemicals, they have been attracting attention as functional materials such as ferroelectric liquid crystal and organic non-linear materials in recent years. For example, in the field of organic non-linear materials, molecules of organic materials preferably have an asymmetric center for producing secondary non-linear optical effect (e.g., Yamaguchi, Nakako and Fueno, “Kagaku” (Chemistry) 42 (11), 757 (1987)). In the field of ferroelectric liquid crystal compounds, liquid crystal compounds are required to have an optically active structure for a liquid crystal exhibiting ferroelectricity (e.g., Johno, Fukuda, Journal of Organic Synthesis Chemistry Society, 47 (6), 568 (1989)).
In recent years, further, anti-ferroelectric liquid crystal is attracting considerable attention, while the anti-ferroelectric liquid crystal compounds are required to have an optically active structure like a ferroelectric liquid crystal. In the above fields, optically active 2-butanol, 2-octanol, 2-methyl-1-butanol or an amino acid derivative has been used as an optically active source.
However, the obtained optically active materials are limited in characteristics so long as the above optically active compounds are used as sources.
In the field of ferroelectric liquid crystals, attempts are recently being vigorously made to synthesize ferroelectric liquid crystals from the following alcohols in which a fluoroalkyl group is substituted on their asymmetric carbon atoms as optically active alcohols (e.g., JP-A-64-3154, JP-A-1-316339, JP-A-1-316367, JP-A-1-316,372, JP-A-2-225,434 and JP-A-2-229,128).
(1) CF
3
C*H(OH)CH
2
COOC
2
H
5
(2) CF
3
C*H(OH)CH
2
CH
2
OC
2
H
5
(3) CF
3
C*H(OH)CH
2
CH
2
CH
2
OC
2
H
5
(4) CF
3
C*H(OH)CH
2
CH
2
CH
2
CH
2
OC
2
H
5
(5) CF
3
C*H(OH)C
6
H
13
(6) CF
3
C*H(OH)C
8
H
17
(7) C
2
F
5
C*H(OH)C
8
H
17
Ferroelectric liquid crystal compounds synthesized from the above alcohols all give high spontaneous polarization and relatively fast response speeds since a fluoroalkyl group having high electro-negativity is substituted on the asymmetric carbon of each. It is also known that a liquid crystal compound synthesized from the above (5), (6) or (7) is likely to give a liquid crystal having an anti-ferroelectric phase, and these alcohols are attracting attention as particularly characteristic alcohols.
Further, with regard to the process for the synthesis of an optically active alcohol of CF
3
C*H(OH)(CH
2
)
m
OC
n
H
2n+1
(in which m is an integer of 2 to 7 and n is an integer of 1 to 4), the present inventors made close studies on the process for the synthesis thereof and a liquid crystal produced therefrom, and it was found that the above alcohol gives very useful anti-ferroelectric liquid crystal or ferroelectric liquid crystal (JP-A-5-65486 and JP-A-8-337555).
When an anti-ferroelectric liquid crystal or a ferrielectric liquid crystal is synthesized from an optically active alcohol containing an asymmetric carbon having a trifluoromethyl group substituted thereon, the so-synthesized liquid crystal shows high spontaneous polarization. When the spontaneous polarization is high, the response speed is fast, which is advantageous in this respect. With an increase in the spontaneous polarization, however, the interaction with an insulating film and an aligned film in an electrode cell is intensified, and the deformation of hysteresis of voltage-optical transmission increases to an extraordinary extent. There is therefore liable to be caused a problem that no drive margin is permitted.
There is therefore desired a liquid crystal which shows a small spontaneous polarization and, on the other hand, which is free of problems in view of a response speed and a tilt angle, and is desired an optically active secondary alcohol which can give substantially such a property.
An optically active secondary alcohol can seem to be produced by various methods.
In view of economic performance, however, it is not expedient to use an optically active compound as a starting material, since it is expensive.
On the other hand, an optically active alcohol may be also produced by asymmetric synthesis. For example, it is thinkable to employ a method in which an optically active alcohol is produced by preparing a corresponding ketone compound as a precursor and asymmetrically reducing it in the presence of an asymmetric reduction catalyst. In this case, however, the asymmetric reduction catalyst is very expensive, and further, a product having a high optical purity cannot be always obtained. Moreover, only one optical active compound of either an R-configuration compound or an S-configuration is obtained.
For example, there is known a method in which a prochiral ketone is asymmetrically reduced in the presence, as a catalyst, of a complex in which (1R,2R)-1,2-diphenyl-2-aminoethanol as a ligand coordinates to a boron atom (J. Yaozhong, et al., Tetrahedron: Asymmetry, 5(7), 1211 (1994)).
The above method is remarkably effective for aromatic ketones. However, it cannot be said that the above method is effective for aliphatic ketones, since obtained enantiomers have a very low optical purity.
In another method, it is thinkable to asymmetrically hydrolyze a proper ester as a precursor for an optically active compound, such as an acetate. An enzyme is used as an effective asymmetric hydrolysis agent. The asymmetric hydrolysis of an acetate with lipase has been proposed by Kitazume et al (T. Kitazume et al., J. Org. 52, 3211 (1987), JP-A-2-282340).
According to Kitazume et al, the acetate of the formula, CF
3
CH(OCOCH
3
)C
n
H
2n+1
is asymmetrically hydrolyzed in the presence of lipase MY in a phosphoric acid buffer solution.
However, the capability of the lipase MY recognizing asymmetry is greatly dependent upon the chemical structure of a compound to be hydrolyzed. And, the optical purity data of obtained hydrolysis products greatly vary from 55 to 98%ee depending upon chemical structures of hydrolyzed compounds as is shown in Table 1 in the above literature by Kitazume et al.
The above results show that it is difficult to pre-calculate whether or not an object compound can be effectively asymmetrically hydrolyzed, and that it is found only after a reaction whether or not an alcohol as an end product having a high optical purity can be obtained.
Further, there is another serious problem that the capability of asymmetry recognition is not at all exhibited when some substituent is on an asymmetric carbon.
For example, lipase MY exhibits the capability of remarkably high asymmetry recognition in the asymmetric hydrolysis of CF
3
C*H(OCOCH
3
)(CH
2
)
5
OC
2
H
5
. However, lipase MY does not show any asymmetry recognition for an ester of a secondary alcohol, CH
3
C*H(OCOCH
3
)C
6
H
13
, in which a methyl group is substituted on the asymmetric carbon.
In addition, an optically active secondary alcohol is also produced by a method in which a secondary racemic alcohol is asymmetrically trans-esterified in the presence of a proper enzyme and the optical resolution thereof is carried out.
For example, there is a method of asymmetric trans-esterification in the presence of a lipase (derived from porcine pancreas) in an organic solvent (A. M. Klibanov, et al., J. Am. Chem. Soc. 1985, 107, 7072).
However, no lipase having high activity and high enantio-selectivity has been known. The asymmetric hydrolysis using an enzyme or the optical resolution by asymmetric trans-esterification is advantageous in that both R-configuration and S-configuration optically active alcohols are easily obtained.
The present invention has been made under the above circumstances, and it is an object of the present i
Mine Takakiyo
Yui Tomoyuki
Lee Howard C.
Maier Leigh C.
Mitsubishi Gas Chemical Company Inc
LandOfFree
Optically active secondary alcohol and process for the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Optically active secondary alcohol and process for the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Optically active secondary alcohol and process for the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2566501