DE3922416A1 - New optically active cpds. with fluoro-substd. asymmetrical carbon - Google Patents

Abstract

New optically active cpds. are of formula (I): R = 1-15C alk(en)yl, opt. with one CN or one or more F or Cl substits., in which one -CH2- gp. may be replaced by -O-, -CO-, -O-CO-, -CO-O- or -O-CO-O-; A1 and A2 independently = opt. mono- or difluoro-substd. 1,4-phenylene, pyridin-2,5-diyl, pyrimidin-2,5-diyl, pyrazin-2,5-diyl, pyridazin-3,6-diyl, 1,3,4-thiadiazol-2,5-diyl, 1,2,4-thiadiazol-3,5-diyl or trans-1,4-cyclohexylene, in which one or two non-adjacent CH2 gps. may be replaced by -O- and/or -S- and/or a CH gp.; Z1-3 independently = -CO-O-, -O-CO-, -CH2O-, -OCH2-, -CH2CH2-, -CH=CH-, -CC- or a single bond; Q1 = -CH2CH2-, -CH2CH2CH2-, -OCH2-, -CH2OCH2-, -OCH2CH2-, -O-CO- or -CO-O-CH2-; Q2 = -O-, -O-CO-, -(CH2)3-O- or a single bond; m = 0, 1, 2 or 3; n = 0 or 1; o = 1-9. (I) can be prepd. (not claimed) by standard methods, e.g. as described in Houben-Weyl, Methoden der Organischen Chemie, Georg-Thieme-Verlag, Stuttgart.

Description

The invention relates to chiral or achiral ring connections of formula I.

wherein
R¹ is an alkyl or perfluoroalkyl group each having 1-12 C atoms, in which one or two non-adjacent CH₂ or CF₂ groups are also represented by O atoms and / or -CO groups and / or -CO-O- Groups and / or -CH = CH groups and / or -CH-halogen and / or -CHCN groups and / or -O-CO-CH-halogen and / or -CO-O- CHCN groups can be replaced,
A¹ and A² each independently of one another 1,4-phenylene which is unsubstituted or substituted by one or two F atoms, in which one or two CH groups can also be replaced by N, and
n means 1 to 12.

The compounds of formula I can be like similar in DE-OS 35 15 373 described compounds as components chiral tilted smectic liquid crystalline Phases are used.

Chiral tilted smectic liquid crystalline phases with ferroelectric properties can be manufactured by using base mixtures with one or more tilted smectic phases with a suitable chiral dopant added (L.A. Beresnev et al., Mol. Cryst. Liq. Cryst. 89: 327 (1982); H.R. Brand et al., J. Physique 44, (lett.), L-771 (1983). Such phases can be used as dielectrics for fast switching displays used on the Clark and Lagerwall described principle of SSFLC technology (N.A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 36: 899 (1980); USP 43 67 924) based on the ferroelectric properties the chirally tilted phase. In this Phase, the elongated molecules are arranged in layers, where the molecules are tilted to the layer normal exhibit. As layer progresses Layer, the tilt direction changes by a small angle with respect to a perpendicular to the layers Axis so that a helical structure is formed. In Displays based on the principle of SSFLC technology the smectic layers are perpendicular to the Arranged plates of the cell. The helical arrangement the tilt directions of the molecules is determined by a very suppressed small distance between the plates (approx. 1-2 µm). This forces the long axes of the molecules arrange themselves in a plane parallel to the plates of the cell, creating two excellent tilt orientations arise. By applying a suitable electrical Alternating field can have a spontaneous polarization liquid crystalline phase between these two  the states are switched back and forth. This Shifting is much faster than conventional ones twisted cells (TN-LCD's) based on nematic Liquid crystals are based.

A major disadvantage for many of the applications currently available materials with chiral tilted smectic Phases (such as Sc *) is their relatively high optical anisotropy due to relatively high viscosity values switching times that are not sufficiently short, as well as that the dielectric anisotropy values greater than zero or, if negative, little of zero has different values. Negative values of the dielectric Anisotropy is required if necessary planar orientation by overlaying the control field with an AC holding field with small amplitude is effected (J.M. Geary, SID conference, Orlando / Florida, April / May 1985, lecture 8.3).

It has now been found that the use of compounds of the formula I as components of chiral tilted smectic Mixtures significantly reduce the disadvantages mentioned can. The compounds of formula I have especially a comparatively large pitch, with which easy orientation in the liquid crystal cell is made possible and are therefore chiral as components tilted smectic liquid crystalline phases excellent suitable. In particular, they are chemical with their help particularly stable chiral tilted smectic liquid crystalline Phases with cheap ferroelectric Phase ranges, especially with broad Sc * phase ranges, negative or positive dielectric Anisotropy, low optical anisotropy, cheaper Pitch height, low viscosity and for such phases high values for spontaneous polarization and very short switching times can be produced. P is the spontaneous Polarization in nC / cm².  

With the provision of the compounds of formula I is also generally the range of liquid crystalline Substances that are different application aspects for manufacturing ferroelectric mixtures are suitable, considerably broadened.

The compounds of formula I have a wide range Scope of application. Depending on the selection of the Substituents can use these compounds as base materials serve from which liquid crystalline phases for the majority are composed; but it can also compounds of the formula I liquid-crystalline base materials added from other classes of compounds, for example the dielectric and / or optical Anisotropy and / or spontaneous polarization and / or the phase range and / or the tilt angle and / or the Pitch and / or the switching times of such a phase too vary. The compounds of formula I are suitable as intermediates for the production of other substances, which are components of liquid crystalline Let phases be used.

The compounds of formula I are in a pure state colorless and show favorable values of optical anisotropy on. Some of the compounds show the formula I liquid crystalline mesophases in one for the electro-optical use of conveniently located temperature range, however, it can also be isotropic or monotropic liquid crystalline compounds of formula I as components chiral tilted smectic phases advantageous be used. Chemical, thermal and against Light they are very stable.

The invention thus relates to the compounds of Formula I and the use of the compounds of the formula I as components of liquid crystalline phases.  

The invention also relates to chiral tilted smectic liquid crystalline phases containing at least a compound of formula I with at least one carbon atom linked to four different substituents.

The invention further relates to such phases containing at least one compound of the formula I. and liquid crystal display elements, in particular electro-optical Display elements that have such phases contain.

Above and below R¹, A¹, A² and n have the indicated Meaning, unless expressly stated otherwise is.

The rest -O-CH₂-CH₂-CHF-C _n H _{2n + 1} is referred to below as R *.

The compounds of formula I accordingly include in particular the preferred compounds of the sub-formulas Ia to If:

These include those of the formulas Ib, Ic and Ie particularly preferred.

In the preferred compounds of the above and below Formulas can be the alkyl radicals, in which also a CH₂ group (alkoxy or oxaalkyl) replaced by an O atom can be straight-chain or branched. Preferably they have 5, 6, 7, 8, 9 or 10 carbon atoms and are preferably pentyl, hexyl, heptyl, octyl, Nonyl, decyl, pentoxy, hexoxy, heptoxy, octoxy, nonoxy or decoxy, also also ethyl, propyl, butyl, undecyl, Dodecyl, propoxy, ethoxy, butoxy, undecoxy, dodecoxy, 2-oxapropyl (= 2-methoxymethyl), 2- (= ethoxymethyl) or 3-oxabutyl (= 2-methoxypentyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl.

A¹ and A² are preferably each independently a 1,4-phenylene (Phe), a pyrimidine-2,5-diyl (Pyr), a pyridine-2,5-diyl- (pyn), a pyrazine-3,6- diyl or a pyridazine-2,5-diyl group, in particular preferably Phe, Pyr or Pyn. Preferably contain the compounds according to the invention not more than a 1,4- Phenylene group, in which one or two CH groups by N are replaced.

Compounds of the formula I and are particularly preferred of the preceding sub-formulas, which are a grouping -Phe-Phe-, Phe-Pyr or Phe-Pyn included. Especially the groups are preferred  

being the 1,4-phenylene rings also substituted by one or two fluorine atoms can be, as well as unsubstituted or or 4,4'-biphenylyl substituted by fluorine.

Compounds of the formulas above and below with branched ones Wing groups R¹ can be important. Ramified Groups of this type usually do not contain more than two chain branches. R1 is preferred a straight-chain group or a branched group with no more than a chain branch.

Preferred branched radicals are isopropyl, 2-butyl (= 1- Methylpropyl), isobutyl (= 2-methylpropyl), tert.-butyl, 2-methylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 2-ethylhexyl, 5-methylhexyl, 2-propylpentyl, 6-methylheptyl, 7-methyloctyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy, 2-oxa-3-methylbutyl, 3-oxa-4- methylpentyl.

The rest R¹ can also be an optically active organic Rest with an asymmetric carbon atom.

Among the compounds of formula I and Ia to If are preferred those in which at least one of them is included contained residues one of the preferred meanings indicated Has.  

R¹ is preferably straight chain alkyl or alkoxy with 5 to 12 carbon atoms.

The compounds of formula I are known per se Methods produced as described in the literature (e.g. in the standard works such as Houben-Weyl, methods of organic chemistry, Georg-Thieme-Verlag, Stuttgart) are described, namely under reaction conditions, known and suitable for the above-mentioned implementations are. You can also from well-known, here make use of variants not mentioned in more detail.

If desired, the starting materials can also be in situ are formed such that they can be removed from the reaction mixture not isolated, but immediately to the Reacts compounds of formula I.

So for the preparation of compounds of formula I suitable precursors from optically active malic acid following reaction scheme:

Up to this stage, the synthesis by Mori et al. (K. Mori, T. Takigawa and T. Matsuo, Tetrahedron 35, 933-944 (1979).

Later Meyers and Lawsson found that the chemical purity of the acetonide obtained in this way is only about 90% (A.I. Meyers and J.P. Lawson, THL 23, 4883-4886 (1982).

Nevertheless, the free alcohol group of the acetonide can be etherified by one of the usual methods (e.g. C. A. Brown and D. Barton, Synthesis (1974) 434 or B.R. Jursic, Tetrahedron 44, 6677-6680 (1988).

The benzyl ether (K. Isaac and P. Kocienski, J. Chem. Soc., Chem. Commun. (1982) 460-462) is particularly useful as a protective group, since it later becomes slightly hydrogenolytic can be split off. Under standard conditions after etherification the isopropylidene ketal to 1,2-diol hydrolyzed and this then according to the reaction conditions by Di Fabio and Misiti in the corresponding Epoxy transferred (R. Di Fabio and D. Misiti, Gazetta Chimica Italiana 118, 209-210 (1988).

Treatment of the acetonide with HBr / glacial acetic acid and the subsequent implementation of those obtained in this way Bromooxalkylacetate with K-Pentanolat delivers accordingly the work of U. Schmidt et al. also the desired ones Epoxies (U. Schmidt, J. Tabiersky, F. Bartowiak and J. Wild, Angew. Chem. 92, 201-202 (1980).  

The implementation of the epoxide with organometallic compounds, preferably with Grignard compounds, results in Ring opening on the less substituted C atom of the epoxide with high selectivity the corresponding alcohol, the fluorinated with DAST under standard conditions. Hydrogenolysis finally delivers the target alcohol, whose reactive derivatives (e.g. tosylates) for etherification of Phenolates can be used.

The required phenols are known or can be found in Analogy to known phenols.  

The optically active compounds of formula I are obtained through the use of appropriate optically active starting materials and / or by separating the optical antipodes using chromatography according to known methods.

The phases according to the invention contain at least one, preferably at least two compounds of the formula I. Chiral tilted ones according to the invention are particularly preferred smectic liquid crystalline phases, their achiral Base mixture in addition to compounds of formula I at least another component with negative or amount contains small positive dielectric anisotropy. The chirality is preferably partially or completely based on chiral compounds of formula I. These Phases preferably contain one or two chiral compounds of formula I. However, it can also be achiral Compounds of formula I (for example in the form of a Racemates) are used, with the chirality the phase caused by other optically active compounds becomes. If chiral compounds of the formula I are used in addition to the purely optical ones Antipodes also mixtures with an enantiomeric excess. The above-mentioned other component (s) of the achiral Base mixture can be 1 to 50%, preferably 10 to 25%, make up the base mix. As additional components with small positive or negative dielectric Anisotropy are suitable compounds of the sub-formulas Va to Vp:

R⁴ and R⁵ are each preferably straight chain or branched alkyl, alkoxy, alkanoyloxy or alkoxycarbonyl with 3 to 12 carbon atoms each. X ′ ′ is O or S, preferably O. n is 0 or 1.  

The compounds of the sub-formulas are particularly preferred Va, Vb, Vd and Vf, where R⁴ and R⁵ are each straight chain Alkyl or alkoxy, each with 5 to 10 carbon atoms means.

The compounds of the sub-formulas Vc, Vh and Vi are suitable themselves as additives for lowering the melting point and normally the base mixes with no more than 5%, preferably 1 to 3% added. R⁴ and R⁵ mean in the compounds of the sub-formulas Vc, Vh and Vi are preferred straight chain alkyl with 2 to 7, preferably 3 to 5, carbon atoms. Another for lowering the melting point suitable class of compound in the phases according to the invention is that of the formula

wherein R⁴ and R⁵ preferred those given for Vc, Vh and Vi Have meaning.

As further components with negative dielectric Anisotropy are also suitable containing compounds the structural element M, N or O.

Preferred compounds of this type correspond to the formulas VIb and VIc:  

R 'and R' 'each preferably represent straight-chain Alkyl or alkoxy groups, each with 2 to 10 carbon atoms. Q¹ and Q² each represent 1,4-phenylene, trans-1,4-cyclohexylene, 4,4'-biphenylyl, 4- (trans-4-cyclohexyl) phenyl, trans, trans-4,4'-bicyclohexyl or one of the groups Q¹ and Q² also a single bond.

Q³ and Q⁴ each represent 1,4-phenylene, 4,4'-biphenylyl or trans-1,4-cyclohexylene. One of the groups Q³ and Q⁴ can also mean 1,4-phenylene, in which at least one CH group is replaced by N. R '' 'is an optical active residue with an asymmetric carbon atom the structure

R '' 'preferably the formula

with the preferred meanings mentioned above.

Particularly preferred components with negative dielectric Anisotropy are those described in WO 86-00529 Connections with the structural element M or N. Especially those of the formula VId are preferred

wherein alkyl is a straight chain or branched alkyl group is preferably 3 to 10 carbon atoms and R 'is the above Has meaning. Connections are also preferred correspond to formula VId, wherein one or both of them Rings linking single bonds through a group selected from -CH₂CH₂-, -O-CO- or -CO-O- are replaced. Particularly preferred compounds of the formula VIc are those of formula VIc ′:

wherein A 1,4-phenylene or trans-1,4-cyclohexylene, Z ° CH or N and N represents 0 or 1.

The compounds of formula I are also suitable as components nematic liquid crystalline phases, e.g. B. for Avoiding reverse twist.

These liquid-crystalline phases according to the invention exist from 2 to 25, preferably 3 to 15 components, including at least one compound of formula I. Die other ingredients are preferably selected from the nematic or nematogenic substances, in particular the known substances from the classes of azoxybenzenes, Benzylidene anilines, biphenyls, terphenyls, phenyl or cyclohexyl benzoates, cyclohexane carboxylic acid phenyl or cyclohexyl esters, phenylcyclohexanes, cyclohexylbiphenyls, Cyclohexylcyclohexanes, cyclohexylnaphthalenes, 1,4-bis-cyclohexylbenzenes, 4,4'-bis-cyclohexylbiphenyls, Phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridazines as well as their N-oxides, phenyl- or cyclohexyldioxanes, Phenyl- or cyclohexyl-1,3-dithiane,  1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2- cyclohexylethanes, optionally halogenated stilbenes, Benzylphenyl ether, tolanes and substituted cinnamic acids.

The most important as components of such liquid crystalline Leave phases in question are characterized by the formula I ′,

R′-L-G-E-R ′ ′ (I ′ ′)

where L and E each have a carbocyclic or heterocyclic ring system from 1,4-disubstituted benzene and cyclohexane rings, 4,4'-disubstituted biphenyl, phenylcyclohexane and cyclohexylcyclohexane systems, 2,5-disubstituted Pyrimidine and 1,3-dioxane rings, 2,6-disubstituted Naphthalene, di- and tetrahydronaphthalene, quinazoline and tetrahydroquinazoline formed group,

G
-CH = CH-
-CH = CY-
-C≡C-
-CO-O-
-CO-S-
-CH = N-
-N (O) = N-
-CH = N (O) -
-CH₂-CH₂-
-CH₂-O-
-CH₂-S-
-COO-Phe-COO-
or a single CC bond,
Y halogen, preferably chlorine, or -CN, and

R ′ and R ′ ′ alkyl, alkoxy, alkanoyloxy, alkoxycarbonyl or alkoxycarbonyloxy with up to 18, preferably up to to 8 carbon atoms, or one of these residues also CN, NC, NO₂, CF₃, F, Cl or Br mean.  

For most of these compounds, R 'and R' 'are from each other different, one of these residues usually one Is alkyl or alkoxy group. But also other variants the proposed substituents are common. Lots such substances or mixtures thereof are commercially available available. All of these substances are known from the literature Methods available.

The phases according to the invention contain about 0.1 to 99, preferably 10 to 95%, one or more compounds of formula I. Also preferred are liquid crystalline according to the invention Phases containing 0.1-40, preferably 0.5-30% of one or more compounds of the Formula I.

The phases according to the invention are produced in in a usual way. As a rule, the components dissolved in one another, expediently at elevated temperature.

By means of suitable additives, the liquid crystalline Phases according to the invention are modified so that they in all types of liquid crystal display elements that have become known can be used.

Such additives are known to the expert and in the Literature described in detail. For example, you can Conductive salts, preferably ethyl-dimethyl-dodecyl-ammonium 4-hexyloxybenzoate, tetrabutylammonium tetraphenylboranate or complex salts of crown ethers (cf. e.g. I. Haller et al., Mol. Cryst. Liq. Cryst. Volume 24, pages 249-258 (1973)) to improve conductivity, pleochroic Dyes for making colored guest host Systems or substances for changing the dielectric Anisotropy, viscosity and / or orientation the nematic phases are added.  

Such substances are e.g. B. in DE-OS 22 09 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430, 28 53 728 and 29 02 177.

The following examples are intended to illustrate the invention, without limiting it. Mp. = Melting point, Kp. = Clearing point. Percentages above and below mean percentages by weight; all temperatures are given in degrees Celsius. "Normal work-up" means: water is given added, extracted with methylene chloride, separated, dried the organic phase, evaporates and purifies the product by crystallization and / or chromatography.

It also means:
K: crystalline solid state, S: smectic phase (the index indicates the phase type), N: nematic state, Ch: cholesteric phase, I: isotropic phase. The number between two symbols indicates the transition temperature in degrees Celsius.

Example 1 Preparation of 5-decyl-2- (p- (3-fluorodecyl-1-oxy) phenyl) pyrimidine

Excluding moisture, add to a mixture of 0.1 with ice cooling mol 5-decyl-2-p-hydroxyphenylpyrimidine, 0.105 mol optically active 3-fluoro- 1-decanol and 0.1 mol triphenylphosphine in THF dropwise 0.1 mol diethylazodicarboxylate so that the reaction temperature does not exceed 10 ° C. The reaction mixture is then slowly allowed to reach room temperature heat and stir for 48 hours. The solvent is then stripped off in vacuo, the residue extracted with 3 × 100 ml of toluene and the toluene phase over silica gel pillared. After evaporation of the solvent, the product is through Crystallization cleaned.  

5-Decyl-2-p-hydroxyphenylpyridine, 4-octyloxy-2,3- difluoro-4'-hydroxybiphenyl, 4-octyloxy-4'-hydroxy-2 ', 3'-difluorobiphenyl and 4-Octyloxy-4'-hydroxybiphenyl with optically active 3-fluoro-1-decanol after Mitsunobu (Synthesis 1, 1981.) etherified.

Claims (4)

1. Chiral or achiral ring compounds of the formula I. wherein
R¹ is an alkyl or perfluoroalkyl group each having 1-12 C atoms, in which one or two non-adjacent CH₂ or CF₂ groups are also represented by O atoms and / or -CO groups and / or -CO-O- Groups and / or -CH = CH groups and / or -CH-halogen and / or -CHCN groups and / or -O-CO-CH-halogen and / or -CO-O- CHCN groups can be replaced,
A¹ and A² each independently of one another 1,4-phenylene which is unsubstituted or substituted by one or two F atoms, in which one or two CH groups can also be replaced by N, and
n means 1 to 12. 2. Chiral tilted smectic liquid crystalline phase with at least two liquid crystalline components, characterized in that it has at least one connection of formula I according to claim 1.   3. Use of the compounds of formula I according to claim 1 as components of liquid crystalline phases. 4. Electro-optical display element, characterized in that that it is a dielectric as a phase according to claim 2 contains.