JP2525156B2 - Amino acid derivative and device suitable for use in liquid crystal material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to liquid crystal compounds derived from amino acids and materials and devices using these compounds. The invention relates in particular to a liquid crystal phase which exhibits the ferroelectric behavior of compounds of this type and the use of said compounds as dopants for producing mixtures which are capable of forming a phase with ferroelectric properties.

Liquid crystal materials exhibiting a graded chiral smectic phase are described, for example, by NA Clark and ST Lagerwall in App. Phys. Lett.
As described in 6,899 (1980) (Reference Material 1), use in high-speed switch electro-optical devices, processing and storage devices based on the ferroelectricity of a graded chiral smectic phase has been proposed.

The liquid crystal materials described in Reference Material 1, DOBAMC (p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate) and HOBACPC (L-4-hexyloxybenzylidene-4'-amino-2-chloro). Propyl cinnamate) is far from ideal in most applications. Because these materials have relatively low chemical stability, they are sensitive to light, their spontaneous polarization coefficient (Ps) is relatively small, the graded smectic phase occurs at high temperatures that are not practical, and only in a narrow temperature range. Because it does not exist.

A liquid crystal material exhibiting a smectic phase, preferably a smectic c (referred to as Sc) phase because it is the most fluid one or more chiral compounds (having optical activity)
It is becoming increasingly common to prepare ferroelectric smectic liquid crystal mixtures by mixing them with chiral chiral smectic phases of the materials, for example ▲ S ^* _c ▼ (the asterisk indicates chiral). It is becoming popular. In this case, the smectic liquid crystal material is called "host", and the chiral compound is called "dopant". The dopant is preferably a large Ps in the mixture.
The one that causes The dopant also preferably exhibits a smectic liquid crystal phase, which is an indicator of compatibility with the smectic lattice, but this is not essential.

With the increasing use of ferroelectric liquid crystal materials such as large screen displays of A4 size and above, it is desirable to reduce the cost of these materials as much as possible. In the case of chiral dopants, the special problem of synthesizing optically pure enantiomers causes high costs.

Biochemical processes are often highly stereospecific, producing optically pure compounds, as well as having the advantage that certain biochemical products are very inexpensive. It would be extremely useful if biochemical products of this kind could be used in the manufacture of liquid crystal materials. One attempt to achieve this is disclosed in published pending PCT application GB85 / 00512. The compound in this PCT application is a lactic acid compound.

One of the aims of the present invention is to further explore the potential of natural products in order to find a group of useful liquid crystal compounds and materials.

The first aspect of the present invention relates to α-aminocarboxylic acid derivatives. This derivative is optically active and has the general formula I Indicated by.

In the formula, A is CH ₃ , CH ₃ (CH ₂ ) ₃ , CH ₂ OB, CH ₃ CH (CH ₃ ), CH ₃ CH (OB), BSCH.
₂ , CH ₃ CH (CH ₃ ) CH ₂ , CH ₃ CH ₂ CH (CH ₃ ), CH ₃ SCH ₂ CH ₂ , BOOCCH ₂ , BOOCCH ₂ CH ₂ , B ₂ NCOCH ₂ , B ₂ NCOCH ₂ CH ₂ , B ₂ NCH ₂
CH ₂ CH ₂ , B ₂ NCH ₂ CH ₂ CH ₂ CH ₂ , [In the formula, B represents a group containing no hydrogen which causes a strong hydrogen bond. ] And X and Y are each independently represented by the following general formula II [Wherein R ₁ is selected from hydrogen, halogen or C _1-20 alkyl, alkoxy, fluoroalkyl, fluoroalkoxy, alkoxy substituted alkyl, alkylcarbonyloxy and alkoxycarbonyloxy, and each of the bonds C, D and E is Single bond COO, OOC, CH ₂ CH ₂ , CH
₂ O, OCH ₂ , CH = N and N = CH are independently selected from a cyclic group Each is independently selected from among optionally substituted phenyl, trans-cyclohexyl, pyridyl, pyrimidyl, dioxane, piperidine, piperazine and bicyclo (2,2,2) octane, and each of c, d and e is separately selected. Represents 0 or 1, and the sum of (c + d + e) of X and (c + d + e) of Y is 2, 3 or 4
With the proviso that Y may be a (CH ₂ ) _n group in which E is n = 0 to 12].

Many of the compounds of formula I can be used as chiral dopants in ferroelectric smectic liquid crystal mixtures with hosts as described above. Adaptability to this type of application is one of the factors that structurally influences other adoptions described below.

Group A is a residue of a naturally occurring α-amino acid, the origin of which is shown in Table 1. The residue shown in the right column of this table is a side chain extending from the chiral center to which the α-amino functional group and carboxylic acid functional group constituting the amide link and the ester link shown in Formula I are bound. is there. Some of the residues shown in Table I are, for example, -OH of serine, -of cysteine.
It contains functional groups such as SH, --COOH of aspartic acid, --NH of tryptophan and --NH ₂ of ornithine. Hydrogen atoms present in these residual functional groups may in some cases participate in hydrogen bonding which can raise the melting point of compounds containing these functional groups, but this raising of the melting point is detrimental to the use of liquid crystals. , So that the group B is introduced in order to reduce the possibility of hydrogen bonding or to avoid it altogether.

The presence of these functional groups in the α-amino acid side chain avoids the problem of hydrogen bonding, in addition to or in addition to the α-amino functional groups and carboxylic acid functional groups bound to the chiral center, It can also be used to effect the attachment to the groups X and Y.

Therefore, the present invention has the following general formula III having optical activity. Also relates to an α-aminocarboxylic acid derivative represented by

In the formula, t is 0 or 1, T ₁ represents a group of the general formula II when t = 0, and T ₂ represents an —OR ₂ group, an NHR ₃ group or an NR ₃ R ₄ group [in the formula:
R ₂ , R ₃ and R ₄ represent an unbranched, branched or chiral alkyl group having 1 to 20 carbon atoms] or t = 1 and T ₂ is of the general formula II And T ₁ represents an unbranched, branched or chiral alkyl group having 1 to 20 carbon atoms, W is the following group, T ₃ COOCH ₂ , CH ₃ CH (OOCT ₃ ), T ₃ SCH ₂ , T ₃ OOCCH ₂ CH ₂ , T ₃ CONBCH ₂ CH ₂ , T ₃ CONBCH ₂ CH ₂ CH ₂ CH ₂ , T ₃ NBCH ₂ CH ₂ CH ₂ CH ₂ , [Wherein T ₃ represents a group of the general formula II, B may be hydrogen or the groups mentioned above, and (c + d + in all of the groups T ₁ , T ₂ and T ₃
The sum of e) is 2, 3 or 4].

From the third aspect of the present invention, α having optical activity is used.
One of the aminocarboxylic acid derivatives is [Wherein W is defined as above].

The group B in formulas I, III and IV may be any organic group which does not contain a hydrogen atom which results in a strong hydrogen bond.
Preferred B groups are alkyl, preferably C ₁ -20n- alkyl, in particular methyl, -OH in residues A, -SH, are employed in the substitution of = NH or -NH ₂ functional groups. -OH, = NH in residue A
Or another preferred group substituting the --NH ₂ functional group is acyl,
That is, R-CO- [wherein R is C1-20 alkyl, preferably n
Represents alkyl, especially methyl], and these functional groups, for example —NH in residue A derived from ornithine
_An ester group or an amide group is formed with a bifunctional group.

Of course, an α-amino acid residue containing no functional group such as α-amino acid residue
It is preferred to use alamin, valine, leucine, isoleucine or phenylalamine without the group B in the compounds of formula I.

With respect to the group of formula II, the cyclic group is in the case of pyrimidine
It is preferably 2,5-linked 1,3-pyrimidine, and in the case of dioxane is preferably trans-dioxane. In the case of cyclohexane where the cyclic group is substituted, the substituent is at the 1 and / or 4 position, eg It is preferable to arrange it in the formula [S is a substituent]. Preferred substituents on the cyclic groups are _{CH 3, CF 3, CH,} F, Cl, Br or COCH _3, in particular F. For cyclic groups attached to a CO or COO group of formula I or III, the substituents are preferably located at ring positions adjacent to the CO or COO group. In this way, the mesogenic (liquid crystal forming) group of the formula II does not stereoscopically rotate relative to the chiral center. When R ₁ is not H, it is preferably an unbranched organic chain of 1 to 20 carbon atoms. When two groups of formula II are present in a compound of formula I or III, for example X and Y, T ₁ and
When T ₃ or T ₂ and T ₃ are present, these groups have the formula II
May have the same or different structures as far as possible.

(C + d +) of the group of formula II in the compound of formula I or III
The sum of e) is preferably 2 or 3. The group of formula II is α
The groups C, D or E which are attached to the CO units of the amino acid are preferably single bonds.

X and Y in Formulas I and III, T ₁ and T ₃ , T ₂ and T ₃
Table 2 shows a preferred combination example of Each Ph represents an optionally substituted phenyl, each Cy represents an optionally substituted trans-cyclohexane, and each BCO is bicyclo (2,2,2).
Represents octyl, and each Py is pyridine or 2,5-bonded 1,3-
Represents a pyrimidine, and each Dx represents a 2,5-linked 1,3-dioxane. Each group R in Table 2 is independently selected from the same groups as when selecting R ₁ in formula II and may be the same or different from each other, preferably both n-alkyl or n
-Alkoxy.

R in X or T ₁ is preferably n-alkyl or n-alkoxy containing 5 to 12 carbon atoms. R in Y or T ₂ is preferably n-alkyl containing 1 to 12 carbon atoms.

Particularly preferred combinations of X and Y of formula I are shown in Table 3.
R _A in the formula is n-alkyl or n-alkoxy having 5 to 12 carbon atoms. R _B in the formula is n containing 1 to 12 carbon atoms.
-Alkyl, especially ethyl, butyl or hexyl, R _C is n-alkyl or n-alkoxy containing 1 to 12 carbon atoms, especially ethyl, butyl, hexyl, ethoxy, butyloxy or hexyloxy. A is as described above, especially CH ₃ , CH ₃ CH (CH ₃ ), CH ₃ CH (CH ₃ ) CH ₂ , CH ₃ CH ₂ CH (CH ₃ ), or Is.

Also, particularly preferred T ₁ , T ₂ and T ₃ are selected from the group of Table 4. R _A , R _B , and R _C in the formula are the same as in Table 3.

The compounds of formula I, III and IV can be prepared by the following procedure.

Starting materials for preparing the compounds of formulas I, III and IV include naturally occurring, preferably commercially available α-aminocarboxylic acids, preferably those having a chiral center, such as alanine, serine, valine, threonine, cysteine, Leucine, isoleucine, methionine, phenylalanine, tyrosine, tryptophan, aspartic acid, glutamic acid, asparagine, glutamine, ortinin, lysine,
Arginine and cystine are preferred.

It should be noted that serine, threonine and tyrosine contain a hydroxy functional group (-OH) in the side chain, and aspartic acid and glutamic acid have a carboxyl functional group (CO ₂ H) in the side chain.
Including asparagine and glutamine include an amide functional group (-CONH ₂ ) in the side chain, ornithine, lysine and arginine include an amino functional group (-NH ₂ ) in the side chain, and cysteine has a mercapto functional group in the side chain. Group (-SH).

To prepare the compounds of formula I, both the amino and carboxyl termini of the α-aminocarboxylic acid may be extended.

 The extension of the amino group is performed by the following formula.

H ₂ N.CH (A). CO ₂ H + XCOCl → X.CONH.CH (A). X in the CO ₂ H formula is the same as above, and A represents the rest of the α-amino acid residue. For example, X is 4-alkyl or 4
-Alkoxy-phenyl or 4'-alkyl or 4 '
-Alkoxy-bien-4-yl, where A is -C
H _3, -CH ₂ -OH or Good.

The method of extending the carboxyl terminus depends on whether the acid contains a functional group in the side chain. When the acid does not contain a functional group in the side chain, for example, in the case of alanine, valine, leucine, isoleucine, methionine and phenylalanine, the carboxyl group is extended by the method of Route 2 in the attached FIG. In the formula, Y has the same meaning as above, and A represents the rest of the α-amino acid residue. For example, Y is 4-alkyl - or 4-alkoxy-- phenyl or 4'-alkyl - or 4'-alkoxy - well A in Bifuen-4-yl is CH _3.
CH. (CH ₃ ). CH ₂ (leucine) or Good.

When a hydroxyl functional group is present on the side chain, it protects the appropriate blocking group B as described above before extending the carboxyl terminus. The optimal blocking group is methyl (CH
₃ ) Blocking is performed according to route 3 in the attached FIG. R in the formula is the rest of the α-amino acid residue. It will be appreciated that the amino and carboxy termini themselves are temporarily protected by a blocking group and then this protecting group is removed. R of route 3 is, for example, CH ₂ (serine) or Is. The amino and carboxyl termini of the α-aminocarboxylic acid after protection can be extended according to routes 1 and 2, respectively.

When a plurality of carboxyl functional groups (—CO ₂ H) are present on the side chain of α-aminocarboxylic acid, it is possible to extend both carboxyl functional groups. To prepare the compounds of formula I from such dicarboxylic acids, a selective blocking and deblocking treatment for the carboxyl groups is carried out. To this end, route 4 in the attached Figure 3
The method via oxazolinone shown in 1 is advantageous. In the formula, Y has the same meaning as above, and R represents the rest of the amino acid residue. For example, Y may be synonymous with the above-mentioned route 2, R
Is CH ₂ (aspartic acid) or CH ₂ . CH ₂ (glutamic acid) may also be used. The amino terminus can then be extended according to Route 1 above. The β-carboxyl group can be optionally blocked with group B. Most preferably it is blocked with methyl as shown in Route 4.

To prepare the compound of formula III, the amino-terminus or the carboxyl-terminus, as appropriate, and the side chain functional group of the α-amino acid residue may be extended.

When the α-amino acid contains a hydroxyl group in the side chain,
The amino or carboxylic acid terminal may be extended by appropriately combining the above routes 1, 2 and 3. However, when the side chain contains a hydroxyl group, it is necessary to prevent internal esterification of, for example, α-aminocarboxylic acid, and therefore, when the hydroxyl group is extended, the carboxyl group is protected and the carboxyl group is protected. When extending, protect the hydroxyl group.

In order to prepare a compound of the formula III in which the amino terminal of the α-aminocarboxylic acid and the side chain hydroxyl group are extended, route 5 of the attached FIG.
Should be used. X and Y in route 5 have the same meanings as described above, and R is an α-amino acid residue. For example, X is 4
-Alkyl- or 4-alkoxy-phenyl or 4'-
It may also be alkyl- or 4'-alkoxy-biphen-4-yl, Y may be 4-alkyl- or 4-alkoxy-phenyl or 4'-alkyl- or 4'-alkoxy-biphen-4-yl and R is CH ₂ or Good.

In order to prepare the compound of the formula III in which the carboxylic acid terminal of α-aminocarboxylic acid and the side chain hydroxyl group are extended, it is preferable to use the route 6 of the attached FIG. 5 based on the above routes 1 to 3. . In the formula, X and Y have the same meanings as described above, and R is an α-amino acid residue. X, Y and R may have the same meanings as in Route 5 above. The amino group of the product of the final step of Route 5 may be converted to a tertiary amine, or
It may be converted to an amide group that does not contain hydrogen atoms which is susceptible to intervening strong hydrogen bonds by known methods such as treatment with alkyl halides to produce tertiary amines.

When the α-amino acid contains a carboxyl group in the side chain,
Compounds of formula III can be prepared, for example, by extension of the β-carboxylic acid group. In this case, it is necessary to protect the α-carboxylate group when extending the β-carboxyl group. For this purpose, a method via oxazolinone as shown in Route 7 of the attached FIG. 6 is preferable. Route 7
Y in the above has the same meaning as described above, and P ₂ and R represent the rest of the α-amino acid residue. Group Y may be synonymous with route 6 and R
May be synonymous with route 4. The amino terminus of the final route 7 product can be extended synonymously with route 1.

To prepare the compound of formula IV, the side chain functional groups of the α-aminocarboxylic acid may be extended and the non-extended amino- and α-carboxyl termini removed (provided that these are protected by subsequent removal. It may need to be protected temporarily by a group.) The products from the penultimate steps of routes 6 and 7 may exist in zwitterionic state, such as compounds of formula IV.

It will be apparent to those skilled in the art that various modifications of the above routes 1 to 7 are possible. The various steps involved in routes 1 to 7 are not new, but the method of combining these steps is new and the product is new. formula
It will also be apparent to those skilled in the art that compounds of I, III and IV may be prepared in alternative ways.

The compounds of formulas I, III and IV may be isolated in optically active (chiral) or racemic forms. In the former case, the starting amino acids of routes 1 to 7 correspond to (S)-
Or the (R) -isomer, in which case the starting amino acid is racemic. Many amino acids are commercially available.

When it is necessary to produce an optically active product by Routes 1-7, the intermediate and final products are examined to ensure that racemization during production does not destroy the optical activity.

Many of the compounds of formula I and III, especially those exhibiting a smectic phase, are useful as components of ferroelectric smectic liquid crystal mixtures.

Accordingly, another object of the present invention is to provide a ferroelectric smectic liquid crystal material which is a mixture of two or more compounds, at least one of which comprises a compound of formula I or III.

In general, the compounds of formula I and III are more suitable as chiral dopants than smectic hosts. Accordingly, the ferroelectric smectic liquid crystal mixture may include at least one compound of formula I
Or it may consist of a mixture of a compound of III and a smectic host.

The compounds of formula I and formula III can be used as dopants in a wide variety of tilted smectic hosts. Some suitable examples of known hosts are the compounds listed in Table 5 below, or mixtures thereof.

Table 5 In Table 5, R ^A and R ^B are C ₁ -C ₁₂ n-alkyl or n-
Alkoxy, for example R ^A = C ₈ H ₁₇ or C ₈ H ₁₇ O, R ^B = C
₅ H ₁₁ and n = 1 or 2. A particularly preferred series of compounds for use as or in a graded smectic host is Applicant's patent application No. PCT / GB.
A series of esters described in 86/0040. The contents of this patent application are incorporated herein. These esters have the general formula (In the formula, Represents 1,4-phenyl or trans-1,4-cyclohexyl, R ³ represents C ₃ -C ₁₂ alkyl, alkoxy, alkylcarbonyloxy, alkoxycarbonyl or alkoxycarbonyloxy, and j is 0 or 1. , R ⁴
C ₃ -C ₁₂ alkyl or alkoxy, wherein either Q ₁ or Q ₂ is H and the other is F). Of the esters of formula V, the particularly preferred esters used as or in the host when used with a compound of formula I or formula III as a dopant are of the following formulas in which R ⁵ is alkyl or alkoxy: Is.

Ferroelectric smectic liquid crystal materials containing compounds of Formula I or Formula III may include other chiral dopants.
Such other dopants include those in which the chiral smectic phase of the mixture has threaded pitches in the same or opposite directions. If the threaded pitch is opposite,
A mixture with infinite pitch may be obtained, and if the direction of P _s induced by the compound of formula I or formula III and the dopant is allogenic, i.e. in the same direction, the mixture is Can take a large P _s . Some examples of other known dopant types that can be used in this way are listed in Table 6.

Table 6 In Table 6, R ^C is n-alkyl or n-alkoxy, and R ^D may be n-alkyl and, if not present as —COOR ^D , n-alkoxy. R ^C and R ^D may each contain from 1 to 12 carbon atoms. (F) indicates that fluorine substitution may occur.

In addition to the compound of Formula I or Formula III, the host and other chiral dopants that may be present, the ferroelectric smectic liquid crystal material may be used to modify or enhance other properties such as viscosity, liquid crystal transition temperature, birefringence, etc. Known additives may be included if modification of their properties is considered necessary.

A typical ferroelectric smectic liquid crystal mixture containing a compound of formula I or formula III is as follows:

The actual composition is selected according to the properties required. P _s is generally proportional to the amount of chiral dopant present in the mixture, and it is desirable to achieve as high a P _s as possible without sacrificing other desirable properties.

Ferroelectric smectic liquid crystal materials containing compounds of Formula I or Formula III are known types of electro-optical devices utilizing such materials, such as Appl. Phys. Lett. 36, (1980) p899.
It can be used in the electro-optical device generally described in (Reference 1).

The device is, for example, Reference Material 1 or Plen of New York.
“Recent developments in conde” published by um
nsed matter physics, 4 , (1981) p309, which may be the Clark-Lagerwall device. According to yet another aspect of the invention, there is provided a device operating by the ferroelectric effect of a liquid crystal material exhibiting a chiral smectic phase, the device comprising two substrates, at least one of which is optically transparent. , An electrode on the inner surface of the substrate,
And a layer of liquid crystal material sandwiched between the substrates, the liquid crystal material comprising at least one compound of formula I, formula III or formula IV described above. This device can be, for example, a Clark-Lager Wall device.

Examples are provided below for the preparation of compounds embodying the invention and their properties. The abbreviations and symbols used in the following examples have the following meanings.

h = time g = gram mp = melting point bp = boiling point hplc = high performance liquid chromatography C-S _A = transition temperature between crystalline solid and smectic A liquid crystal S _A −I = between smectic A liquid crystal and isotropic liquid Transition temperature [α] = optical diopter (°) NaD line; CHCl ₃ Example 1 Extension of α-amino group by route 1 4-n-octyloxybiphenylenyl-4′-carboxylic acid (10 mmol) , Stirred in dry benzene for 2-3 hours with oxalyl chloride (29 mmol) and dimethylformamide (catalytic amount). The solvent and unreacted oxalin chloride were then removed by vacuum evaporation.

Obtained 4-n-octyloxybiphenylenyl-4 '
-Carbonyl chloride dried dichloromethane (30 ml)
And was added dropwise to a solution of alanine (10 mmol) in a saturated aqueous solution of sodium hydrogen carbonate (100 ml) for 20 minutes with very vigorous stirring. Stirring further
Continued for 30 minutes, the solution was acidified and the organic material was extracted with dichloromethane (3 x 50 ml). The extracts were combined and evaporated to dryness to give the crude amide. This was purified by flash chromatography on silica gel using an ethyl acetate: petroleum fraction (bp 60-80 ° C) 3: 1 eluent.

Was obtained in a yield of 60-70%. The melting point was 215 ° C.

Example 2 Protection of α-amino groups as in Routes 2,3,4,6,7 See M. Bergmann and L. Zervas, Ber. 1982, 11 , 1192.

To a vigorously stirred solution of serine (10 mmol) in 10% aqueous sodium hydrogen carbonate (50 ml) was added benzyl chloroformate (15 mmol) dropwise over about 20 minutes and stirring was continued for another 4 hours.

The solution was carefully acidified with dilute HCl and any precipitate was removed by filtration. If there was no solution or precipitate, the whole solution was shaken with ether (3 x 50 ml). The dry ether extract was evaporated to give the crude product.
This was purified by column chromatography on silica gel with the above precipitate (if any) using an eluent of ethyl acetate: petroleum fraction (bp 60-80 ° C) (3: 1).

Was obtained in a yield of 60%. The mp was 117 ° C.

Example 3 Protection of α-Carboxyl Group as in Routes 3,5,6 See SS Wang, J-Org Chem . 1976, 41, 3258.

The amino group of serine was protected with benzyl chloroformate as in Example 2 above.

A solution of the above protected serine (10 mmol) in a minimum volume of aqueous 80% ethanol was titrated to pH 7 with 20% aqueous cesium carbonate solution. Then add about 35
Removed by evaporation at ° C. Even the last drop of water was removed from the residue by azeotropic distillation of benzene (3X).

A solution of the resulting cesium salt in dry dimethylformamide (50 ml) was stirred with benzyl bromide (1.2 molar equivalents) for 24 hours. The precipitate C _s B _r over by removing Russia, the solvent was removed under vacuum. Add water and add chloroform (3 x
The reaction mixture obtained with 50 ml) was shaken and the dried extract was evaporated to give the benzyl ester. This was purified by silica gel flash chromatography using an ethyl acetate: petroleum fraction (bp 60-80 ° C) 3: 1 eluent.

Was obtained in a yield of 80%. The mp was 77 ° C.

Example 4 Deprotection of amino and carboxylic acid groups as in Routes 2,3,4,5,6,7 Minimize the products of Examples 2 and 3 containing protected amino and carboxyl groups. Dissolved in an amount of a mixture of ethanol and ethyl acetate (10: 1) and hydrogenated in the presence of 7.5% palladium on thiocol (50 mg / g), this was continued until there was no uptake of hydrogen. The catalyst was removed by filtration and the solvent removed under vacuum to give the crude product. This was purified by an appropriate method (eg, recrystallization, chromatography, etc.). Yields were generally 90-100%.

Example 5 Extension of Carboxyl Group as Routes 2,4,5,6,7 A. Hassner and V. Aleanian, Tetrahedron Letters , 197
See 8,4475.

N- (4'-n-octyloxybiphenyl-4-oil) -L-alanine (10 mmol), NN'-dicyclohexylcarbodiimide (11 mmol), 4-n-butoxyphenol (11 mmol) and 4-pyrrolid A mixture of dinopyridine (1 mmol) and dichloromethane (50 ml) was stirred at room temperature to complete the reaction (tlc). Precipitated N
The N'-dicyclohexylurea was removed by filtration and the filtrate was washed successively with water (3 x 50 ml), 5% aqueous acetic acid (3 x 50 ml) and again with water (3 x 50 ml). The organic phase was evaporated to dryness to give the crude ester. This was purified by column chromatography on silica gel using an ethyl acetate: petroleum fraction (bp 60-80 ° C) 3: 1 eluent.

The compound produced is The yield was 86% and the mp was 184-185 ° C.

Similarly, the following two compounds Was adjusted. The _Ps values of these compounds are Each of them was dissolved in 10% to prepare a 10% solution, and the P _s value of the solution was extrapolated to measure. The extrapolated P _s values are
141 and 138.

Example 6 Blocking of the hydroxyl group of the side chain as in Route 3 The terminal amino group and terminal carboxylic acid group were used in Examples 2 and 3, respectively.
The α-aminocarboxylic acid (10 mmol) protected as above was dissolved in acetone (30 ml) in a three-necked round bottom flask. This three-necked round-bottomed flask was equipped with two dropping funnels, one with dimethylsulfate (10 mmol) and the other with 40% w / v sodium hydroxide solution (20 m
l) is included.

About 1/3 sodium hydroxide solution was added to the flask with vigorous stirring, then the flask and its contents were heated to about 50 ° C.
Heated to. While continuing to stir, the remaining sodium hydroxide solution and dimethylsulfate were simultaneously added dropwise over 1.5 hours. The stirring was continued for a further 30 minutes, after which the acetone was removed by distillation under nitrogen. Crush the contents of the flask with ice (10
The solid was collected by filtration and washed with cold water.

Drying under vacuum and recrystallisation in petroleum fraction (bp 60-80 ° C) gave pure methylated product.

Example 7 Preparation of Oxazolinones as in Routes 4 and 7 The amino group of L-aspartic acid was protected with benzyl chloroformate as in Example 2 to give N-benzyloxycarbonyl-L-aspartic acid. Was formed.

Protected acid (5.35g) and paraformaldehyde (1.85g)
A mixture of g), acetic anhydride (4.0 g), acetic acid (75 g) and thionyl chloride (0.3 g) was heated to 100 ° C. for 4 hours. Evaporation of acetic acid under reduced pressure gave an oily residue. This was dissolved in ethyl acetate and shaken with a 5% aqueous sodium hydrogen carbonate solution. Collect the aqueous layers and cool (0-5
(° C) while carefully acidifying. Then shaken aqueous phase with ethyl acetate (3 × 50ml), the ethyl acetate extracts were washed with water (1 × 50ml), dried (M _g SO ₄₎ it was. Removal of solvent gave a pale yellow oily crude product. This was subjected to column chromatography using silica gel to obtain chloroform / ethyl acetate (3: 1).
It refine | purified using the eluent of.

Oxazolinone of the following formula Was obtained as an oil. The yield was 80%.

Example 8 Cleavage of Oxazolinone as in Routes 4 and 7 A solution of oxazolinone (1.5 g) prepared in Example 7 in methanol (20 ml) was treated with 1M sodium hydroxide (10 ml) for 4 hours at room temperature. The reaction mixture was then neutralized with 1M hydrochloric acid and the methanol was removed under reduced pressure. The aqueous solution was shaken with ethyl acetate and then with 5% aqueous sodium hydrogen carbonate solution. The extract was washed with ethyl acetate, acidified by adding 6M hydrochloric acid and shaken with ethyl acetate.

The organic phase was separated, washed with water, dried (M _g SO _4).
Evaporation of the solvent gave an oily residue which solidified on standing. When recrystallized in water, N-benzyl-
Oxycarbonyl-L-aspartic acid was obtained.

Further specific examples of the compounds of formula I and their liquid crystalline properties are shown below. These compounds use route 1 to extend the α-amino group and route 2 to produce α-amino groups.
It was prepared by extending a carboxyl group. The experimental conditions were similar to those in Examples 1 and 5, and the appropriate carboxylic acid, phenol or alcohol was used. (Caution: In the formula below, 8R represents n-octyl and 8RO represents n-octyloxy. The same applies to other compounds) Compounds having the following structures R _A R _B Melting point (° C) [α °] 8RO 2R 103 +50.2 9R 2R 89.5 +51 Compounds with the following structures Compounds with the following structure R _A R _B Liquid crystal transition (℃) 8RO 4RO C-I 184.4 Compounds with the following structures R _A R _B Melting point (° C) [α °] 8RO 2R 130 ＋36.9 6RO 2R 131 ＋32.8 9RO 2R 132 ＋33.7 12RO 2R 131.7 ＋33.8 9RO 2R 197 ＋41.6 10R 2R 131.5 ＋35.3 8RO 4R 129.6 +40.9 9R 4R 109 +41.7 An example of the use of compounds of formula I in liquid crystal materials and devices embodying the invention is illustrated with reference to Figure 7 of the accompanying drawings. FIG. 7 is an end sectional view of the liquid crystal shutter.

The liquid crystal cell of FIG. 7 has a layer 1 of liquid crystal material exhibiting a chiral smectic phase. This layer 1 is sandwiched between a glass slide 2 having on its surface a transparent conductive layer 3 made of, for example, tin oxide or indium oxide, and a glass slide 4 having a transparent conductive layer 5 on its surface. There is. The slides 2,4 with the layers 3,5 are coated with a film 6,7 of polyimide polymer. Before assembling the cell, the films 6 and 7 are rubbed in a predetermined direction with a soft cloth. The rubbing directions are arranged parallel when assembling the cells. A spacer 8 made of polymethylmethacrylate, for example, separates the slides 2, 4 by a predetermined distance, for example 5 microns.

The liquid crystal material 1 fills the space between the slides 2 and 4 and the spacer 8 and the spacer 8 is sealed under vacuum by a known method to introduce the liquid crystal material 1 between the slides 2 and 4. A suitable liquid crystal material 1 is Is.

The polarizer 9 is arranged with its polarization axis parallel to the rubbing direction of the films 6 and 7. An analyzer 10 (crossed polarizer) is arranged with its polarization axis perpendicular to the rubbing direction.

Square-wave voltage varying from approximately +10 to -10 volts (not shown, but can come from a normal source)
Is applied to the cell to bring layers 3 and 4 into contact. The cell can rapidly switch between a dark state and a bright state in response to changes in the sign of the applied voltage.

[Brief description of drawings]

FIG. 1 illustrates Route 2 of the present invention showing a method for extending a carboxyl group. FIG. 2 illustrates Route 3 of the present invention showing a method of blocking hydroxyl groups in the side chain. FIG. 3 illustrates Route 4 of the present invention showing a method of blocking the carboxyl group in the side chain. FIG. 4 illustrates Route 5 of the present invention showing a route for the preparation of compounds of formula III of the present invention. FIG. 5 illustrates Route 6 of the present invention showing another route for the preparation of compounds of formula III of the present invention. FIG. 6 illustrates Route 7 of the present invention showing yet another route for the preparation of compounds of formula III of the present invention. FIG. 7 shows a sectional view of the device of the present invention. 1 ... Liquid crystal material layer, 2 ... Glass slide, 3 ... Transparent conductive layer, 4 ... Glass slide, 5 ... Transparent conductive layer, 6,7 ... Polyimide polymer film, 8 ... Spacer, 9 ...... Polarizer, 10 …… Detector.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C07C 279/14 C07C 279/14 323/59 323/59 C07D 209/20 C07D 209/20 263/18 263/18 295/14 295/14 AZ C09K 19/14 C09K 19/14 19/20 19/20 19/22 19/22 G02F 1/13 500 G02F 1/13 500 (72) Inventor Litchard Michael Scrauston UK, North Humberside H. You 17.18.T.G., Biverly, Walkington, Saunders Craft. 11 (72) Inventor Adam J. Jackson, North Humberside, UK.・ H YOU 3.6 Kew Tay, Hull, Unrevy Road, De La Paul Avue YOU 10

Claims (5)

(57) [Claims] 1. A general formula I [ _Wherein A is a C _1-5 branched or straight-chain alkyl group, CH
₂ OR, where R can be H or methyl, Y is H, C _1-12 alkyl, CH ₂ Ph, and Ph-R (where R is C _1-12 alkyl or alkoxy). X is R-Ph-Ph (R is H, C _1-12 alkyl or alkoxy), Ph-CH ₂ -O, R-Ph-Ph-Z-Ph, or R- Ph-Z-Ph-Ph (R is C _1-12 alkyl or alkoxy, Z is COO or OCO), and there are at least two phenyl rings. -Optically active derivatives of aminocarboxylic acids. 2. A is methyl, Y is selected from H, CH ₂ Ph, Ph—R (wherein R is C _1-5 alkyl or alkoxy), C _1-5 alkyl, and X is , R-Ph-Ph (where R is C _1-12 alkyl or _{alkoxy), Ph-CH 2 O,} R-Ph-Ph-CO 2 -Ph ( where R is C _1-12 alkyl or alkoxy The derivative of claim 1 selected from the group consisting of: 3. The following formula (Where A is CH ₃ and R _A is C _1-5 n-alkyl or n
_-Alkoxy , R _B represents C _1-12 n-alkyl, R _B
C represents C _1-12 n-alkyl or n-alkoxy), and the derivative according to claim 1. 4. A ferroelectric smectic liquid crystal material which is a mixture of at least two compounds, at least one of which has the general formula I [ _Wherein A is a C _1-5 branched or straight-chain alkyl group, CH
₂ OR, where R can be H or methyl, Y is H, C _1-12 alkyl, CH ₂ Ph, and Ph-R (where R is C _1-12 alkyl or alkoxy). X is R-Ph-Ph (R is H, C _1-12 alkyl or alkoxy), Ph-CH ₂ -O, R-Ph-Ph-Z-Ph, or R- Ph-Z-Ph-Ph (R is C _1-12 alkyl or alkoxy, Z is COO or OCO), and at least two phenyl rings are present] A ferroelectric smectic liquid crystal material. 5. An electro-optical device that operates by the ferroelectric effect of a liquid crystal material exhibiting a chiral smectic phase, at least two substrates of which at least one is optically transparent, and on the inner surface of the substrate. Electrode and a layer of liquid crystal material sandwiched between the substrates,
The liquid crystal material has the general formula I [ _Wherein A is a C _1-5 branched or straight-chain alkyl group, CH
₂ OR, where R can be H or methyl, Y is H, C _1-12 alkyl, CH ₂ Ph, and Ph-R (where R is C _1-12 alkyl or alkoxy). X is R-Ph-Ph (R is H, C _1-12 alkyl or alkoxy), Ph-CH ₂ -O, R-Ph-Ph-Z-Ph, or R- Ph-Z-Ph-Ph (R is C _1-12 alkyl or alkoxy, Z is COO or OCO), and at least two phenyl rings are present]. Characterized by containing at least one,
Electro-optical device.