WO2019034588A1 - Liquid-crystalline compounds - Google Patents

Abstract

The invention relates to compounds of formula (I), wherein the alkyl/alkenyl moieties R1 and R2 have the meanings specified in claim 1, to a method for the production thereof, to liquid-crystalline media containing at least one compound of formula (I), and to electro-optical displays containing such a liquid-crystalline medium.

Description

 Liquid crystalline compounds

The invention relates to compounds of the formula I,

wherein the alkyl / alkenyl radicals R ¹ and R ^{2 are} as defined below, a process for their preparation, liquid-crystalline media containing at least one compound of formula I and their use as component (s) in liquid-crystalline media. Moreover, the present invention relates to liquid crystal and electro-optical

Display elements which contain the liquid-crystalline media according to the invention.

In recent years, the applications of liquid crystalline compounds to various types of display devices, electro-optical devices, electronic components, sensors, etc. have been greatly expanded. For this reason, a number of different structures have been proposed, especially in the field of nematic liquid crystals. The nematic liquid-crystal mixtures have hitherto found the widest application in flat display devices. They were particularly used in passive TN or STN matrix displays or systems with a TFT active matrix.

The liquid-crystalline compounds according to the invention can be used as component (s) of liquid-crystalline media, in particular for displays based on the principle of the twisted cell, the guest-host effect, the effect of deformation of upright phases DAP or ECB (electrically controlled birefringence), based on the IPS effect (in-plane switching) or the effect of dynamic dispersion.

The use of liquid crystalline substances with a

Cydohexene ring and a total of three rings is known in the art. There have been various compounds with a Cydohexenring as a liquid crystalline or mesogenic material and its preparation described, such. B. in the document Liquid Crystals, 1997, 23, 69-75 (VS Bezborodov et al.). One of the compounds proposed therein has a cylohexene ring besides a biphenyl unit and as

End groups pentyl and methyl.

It is an object of the present invention to find novel stable compounds which are suitable as component (s) of liquid-crystalline media. In particular, the compounds should simultaneously have a comparatively low viscosity, as well as a high optical

Possess anisotropy.

With regard to the most diverse applications of such high-Δη compounds, it has been desired to have available further compounds, preferably with a high clearing point and low viscosity, which have precisely tailor-made properties for the respective applications.

The invention was thus an object of new stable

Find compounds that as component (s) liquid-crystalline media, in particular for z. As TN, STN, IPS, FFS and TN TFT displays are suitable.

In addition, the compounds of the invention should be thermally and photochemically stable under the conditions prevailing in the fields of application. As mesogens they should have a broad

enable nematic phase in mixtures with liquid crystalline co-components as well as be miscible with nematic base mixtures, especially at low temperatures. Also preferred are substances with a low melting point and a low enthalpy of fusion, since these quantities are in turn indicative of the above-mentioned desirable properties, such as. As a high solubility, a broad liquid crystalline phase and a low tendency for spontaneous crystallization in mixtures at low temperatures. Especially the solubility at low temperature while avoiding any crystallization is important for the safe operation and transport of displays in vehicles and aircraft and outdoors. Surprisingly, it has been found that the compounds according to the invention are outstandingly suitable as components of liquid-crystalline media. With their help, liquid-crystalline media can be obtained for displays that require particularly high optical anisotropies, in particular for IPS and FFS displays, but also for TN or STN displays. The compounds of the invention are sufficiently stable and colorless. In particular, they are characterized by neutral to slightly positive dielectric anisotropy Δε. They are well soluble for compounds with comparable properties. In addition, the compounds according to the invention have a comparatively very high clearing point and at the same time low values for the rotational viscosity. The compounds have relatively low melting points. Surprisingly, it is possible with the compounds according to the invention to prepare liquid-crystalline mixtures having high elastic constants and a low ratio of the rotational viscosity to the elastic constant K ¹¹ without adversely affecting the other application parameters. This results in media with low switching time and high contrast.

With the provision of the compounds according to the invention is quite generally the range of liquid-crystalline substances, which vary from various application aspects

Production of liquid-crystalline mixtures are significantly widened.

The invention thus relates to compounds of the formula I,

in which an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -C ^ C-,

-CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

· ^_S - _> -CO-O-, or -O-CO- can be replaced so that O / S atoms are not directly linked to one another, and in which also one or more H atoms can be replaced by halogen, or H .

and an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C 1 -C-,

CF ₂ O-, -OCF ₂ -, / \, ->"^ OO ^

-O-, -S-, -CO-O-, or -O-CO- can be replaced so that O / S atoms are not directly linked to each other, and in which also one or more H atoms are replaced by halogen can, or H, preferably a halogenated or unsubstituted alkenyl radical having 2 to 15 carbon atoms, wherein in these radicals also one or more CH ₂ groups each independently

-CEC-, -CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

-O-, -S-, -CO-O-, or -O-CO- can be replaced so that O / S atoms are not directly linked to each other, and in which also one or more H atoms are replaced by halogen in which R ¹ and R ^{2 are} not simultaneously an alkyl chain having 1 to 15 C atoms, and wherein R ¹ and R ² preferably comprise at least one halogenated or unsubstituted alkenyl radical, in which radical also one or more CH ₂ - Each independently of one another by -C ^ C-, -CF ₂ O-, -OCF ₂ -, ^, - <^> -,

"^ C ^", ^~ 0 ^~ ■ 'S-' -CO-O-, or -O-CO- so be replaced may be that O / S atoms are not directly linked to each other, and in which also one or more H atoms may be replaced by halogen.

The invention further relates to the use of the compounds of the formula I in liquid-crystalline media.

Likewise provided by the present invention are liquid-crystalline media having at least two liquid-crystalline components which comprise at least one compound of the formula I,

wherein the substituents mean:

R ^{1 is} an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C

Atoms, where in these radicals also one or more CH ₂ groups each independently of one another by -C ^ C-,

-CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

· - ° '· -CO-O-, or -O-CO- can be replaced so that O / S atoms are not directly linked to each other, and in which also one or more H atoms may be replaced by halogen, or H,

and an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C 1 -C-,

-CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

· - ° '· -CO-O-, or -O-CO- can be replaced so that O / S atoms are not directly linked to each other, and in which also one or more H atoms may be replaced by halogen, or H.

Preferred liquid-crystalline media according to the invention comprise at least one compound of the formula I according to the preferred Embodiments of the compounds as indicated above and below.

The compounds of the formula I have a wide range of applications. Depending on the choice of substituents, these compounds may serve as base materials from which liquid crystalline media are predominantly composed; However, it is also possible to add compounds of the formula I to liquid-crystalline base materials from other classes of compounds in order, for example, to influence the dielectric and / or optical anisotropy of such a dielectric and / or to optimize its threshold voltage and / or its viscosity.

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in their own or in mixtures in a temperature range which is favorably located for electrooptical use. With the compounds according to the invention, broad nematic phase ranges can be achieved. In liquid-crystalline mixtures, the substances according to the invention significantly increase the optical anisotropy and / or lead to an improvement in the low-temperature storage stability compared to comparable mixtures with a high dielectric content

Anisotropy. At the same time, the compounds are characterized by good UV stability. The radical R ^{1 of} the formula I and its sub-formulas preferably denotes alkyl or alkenyl having up to 8 carbon atoms. R ¹ particularly preferably represents an unbranched alkenyl radical having 2 to 8 C atoms, in particular unbranched alkenyl having 2 to 7 C atoms. The radical R ^{2 of} the formula I is preferably alkyl or alkenyl having up to 8 carbon atoms. R ² particularly preferably means one

straight-chain alkyl radical having 1 to 7 carbon atoms or an unbranched alkenyl radical having 2 to 8 carbon atoms, in particular unbranched alkyl having 1 to 5 carbon atoms. Particularly preferably, one of the radicals R ¹ and R ^{2 is} an alkenyl radical and the other is an alkyl radical. Thus, R ^{1 is more} preferably an alkenyl radical having up to 8 carbon atoms and R ^{2 is} an alkyl radical having up to 8 carbon atoms, or R ^{1 is} an alkyl radical having up to 8 carbon atoms and R ^{2 is} an alkenyl radical having up to 8 carbon atoms

Compounds of formula I with branched or substituted

Wing groups R ¹ and R ² may occasionally for reasons of better solubility in the usual liquid crystal inen base materials of

Meaning. The group R ¹ is preferably straight-chain.

The radical R ¹ is particularly preferably selected from the substructures: -CH = CH ₂

-CH = CH ₂ -CH ₃

-CH ₂ -CH ₂ -CH = CH ₂

-CH ₂ -CH ₂ -CH = CH-CH ₃

wherein the alkenyl chains are preferably E-configured.

Particularly preferred compounds of formula I are the compounds of formulas 1-1 to I-6: alkenyl alkenyl

alkenyl 1.5

wherein alkenyl is independently an alkenyl radical having 2-8 C atoms or one of the meanings given above. Among the compounds of the formulas 1-1 to I-6, the formulas 1-1, I-2, I-5 and I-6 are preferred, in particular the compounds of the formulas 1-1 and I-5.

Very particularly preferred compounds are mentioned below:

 ^^^^ C ^ ^ C ^ M d

The compounds of the formula I are prepared by methods known per se, as described in the literature (for example in the standard works, such as

Houben-Weyl, Methods of Organic Chemistry, Georg Thieme Verlag, Stuttgart) are described under reaction conditions, which are known and suitable for the above reactions. One can also make use of known per se, not mentioned here variants.

Compounds of the formula I can advantageously be used as at

following exemplary synthesis and examples

(Schemes 1 and 2): benzylation

Ketal cleavage

Enol ether cleavage

 r gnar

dehydration

Scheme 1. Synthetic scheme for the preparation of compounds of the Formula I. Bn represents benzyl radical. R ² is a radical R ² as defined in formula I.

A more general synthetic scheme results from this as follows (Scheme

Scheme 2. General Synthetic Scheme for Compounds of Formula I. R ¹ and R ² are as defined in Formula I.

Corresponding starting materials can usually be obtained from

One skilled in the art readily produce by literature methods of synthesis.

Instead of the outlined Grignard compounds for the addition of the biphenyl radical to the cyclohexanone, it is also possible to use aryllithium compounds which are accessible analogously by halogen-metal exchange with alkyllithium compounds at low temperatures (cf., for example, US Pat. No. 4,940,822).

The invention therefore also has a process for the preparation of

The invention relates to compounds of the formula I which comprise a process step in which an arylmetal compound of the formula II

wherein R ^{2 is} as defined for formula I, and

 M means Li, MgBr or MgCl,

with a cyclohexanone compound of the formula III

wherein

R ^{1 is} as defined for formula I, is reacted, and in a further reaction step comprising an elimination of the OH function formed in the preceding reaction step to a compound of formula I:

wherein the groups are as defined above,

is implemented.

The reaction methods and reagents used are in principle known from the literature. Further reaction conditions may be the

Embodiments are taken.

Further, not mentioned above, preferred process variants can be taken from the examples or the claims.

The process and the subsequent work-up of the

Reaction mixture can in principle be carried out as a batch reaction or in a continuous reaction mode. The continuous reaction includes z. As the reaction in a continuous stirred tank reactor, a stirred tank cascade, a loop or cross-flow reactor, a flow tube or in a microreactor. The work-up of the reaction mixtures is optionally carried out, as required, by filtration over solid phases, chromatography, separation between immiscible phases (eg extraction), adsorption on solid supports, distilling off solvents and / or azeotropic mixtures, selective distillation, sublimation, crystallization, cocrystallization or by nanofiltration on membranes.

The invention also liquid-crystalline media containing one or more of the compounds of formula I as defined above, preferably the compounds of the invention and their

preferred sub-formulas. The liquid-crystalline media contain at least two components. They are preferably obtained by mixing the components, for. As mesogenic or liquid crystalline compounds, mixed together. The invention therefore also relates to a liquid-crystalline medium containing at least two mesogenic

Compounds, characterized in that there is at least one

Contains compound of formula I. An inventive method for producing a liquid-crystalline medium is therefore characterized

in that at least one compound of the formula I is mixed with at least one further mesogenic compound and, if appropriate, additives are added.

The achievable combinations of clearing point, low temperature viscosity, thermal / UV stability, dielectric anisotropy, switching time and contrast far exceed previous prior art materials.

The liquid-crystalline media according to the invention contain

preferably in addition to one or more inventive

Compounds as further constituents 2 to 40, more preferably 4 to 30 components. In particular, these media contain, in addition to one or more compounds according to the invention 7 to 25 components. These other ingredients are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of azoxybenzenes,

Benzylideneanilines, biphenyls, terphenyls, phenyl or

Cyclohexyl benzoates, cyclohexane-carboxylic acid-phenyl or

cyclohexyl ester, phenyl or cyclohexyl ester of

Cyclohexylbenzoesäure, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic, Cyclohexylphenylester of benzoic acid, cyclohexanecarboxylic or Cyclohexylcyclohexancarbonsäure, Phenylcyclohexane, Cyclohexylbiphenyls, Phenylcyclohexylcyclohexane, Cyclohexylcyclohexane, Cyclohexylcyclohexylcyclohexane, 1, 4-bis-cyclo-hexylbenzenes, 4,4'-bis-cyclohexylbiphenyls , Phenyl- or cyclohexylpyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyl-dioxanes, phenyl- or cyclohexyl-1,3-dithiane, 1,2-diphenylethane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane , 1-cyclohexyl-2- (4-phenyl-cyclohexyl) -ethanes, 1-cyclohexyl-2-biphenylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated silibens, benzyl phenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be fluorinated.

The most important compounds which may be used as further constituents of the media according to the invention can be characterized by the formulas 1, 2, 3, 4 and 5:

R'-L-E-R "1

 R'-L-COO-E-R "2

R'-L-CF ₂ O "3

R'-L-CH ₂ CH ₂ -ER "4

 R'-L-C = C-E-R "5

In the formulas 1, 2, 3, 4 and 5, L and E, which may be identical or different, each independently of one another represent a bivalent radical from the structural elements -Phe-, -Cyc-, -Phe- Phe, -Phe-Cyc, -Cyc-Cyc, -Pyr, -Dio, -Py, -G-Phe, -G-Cyc and their mirror images formed group, wherein Phe is unsubstituted or by fluorine substituted 1,4-phenylene, Cyc trans-1,4-cyclohexylene, Pyr Pyhmidine-2,5-diyl or Pyridine-2,5-diyl, Dio 1, 3-dioxane-2,5-diyl, Py

Tetrahydropyran-2,5-diyl and G 2- (trans-1,4-cyclohexyl) -ethyl.

Preferably, one of L and E is Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. The media according to the invention preferably comprise one or more components selected from the compounds of the formulas 1, 2, 3, 4 and 5, in which L and E are selected from the group Cyc, Phe and Pyr and simultaneously one or more components selected from the compounds of the Formulas 1, 2, 3, 4 and 5, wherein one of the radicals L and E is selected from the group Cyc, Phe, Py and Pyr and the other radical is selected from the group -Phe-Phe-, -Phe-Cyc- , -Cyc-Cyc-, -G-Phe- and -G-Cyc-, and optionally one or more components selected from the compounds of formulas 1, 2, 3, 4 and 5, wherein the radicals L and E are selected from the group -Phe-Cyc, -Cyc-Cyc, -G-Phe and -G-Cyc-.

R 'and / or R "each independently represent alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or alkanoyloxy having up to 8 C atoms, -F, -Cl, -CN, -NCS or - (O) iCH ₃ -kF _k , where i is 0 or 1 and k is 1, 2 or 3. R 'and R "in a smaller subgroup of the compounds of the formulas 1, 2, 3, 4 and 5 are each independently alkyl, alkenyl, alkoxy, alkoxyalkyl, Alkenyloxy or alkanoyloxy with up to 8 C atoms. In the following, this smaller subgroup will be called Group A and the compounds will be described with the subformulae 1a, 2a, 3a, 4a and 5a

designated. In most of these compounds R 'and R "are different from each other, one of these radicals is usually alkyl, alkenyl, alkoxy or alkoxyalkyl.

In another known as group B smaller subgroup of the compounds of formulas 1, 2, 3, 4 and 5, R "is -F, -Cl, -NCS or - (O) I _3-k F _k, where i is 0 or 1 and k is 1, 2 or 3. The compounds, in where R "has this meaning are designated by the subformulae 1 b, 2b, 3b, 4b and 5b, particular preference is given to those compounds of the subformulae 1 b, 2b, 3b, 4b and 5b in which R" denotes -F, Has -Cl, -NCS, -CF ₃ , -OCHF ₂ or -OCF ₃ .

In the compounds of the subformulae 1 b, 2b, 3b, 4b and 5b, R 'has the meanings given for the compounds of the subformulae 1a to 5a and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl. In a further smaller subgroup of the compounds of the formulas 1, 2, 3, 4 and 5, R "denotes -CN. This subgroup is referred to below as group C and the compounds of this subgroup are correspondingly reacted with partial formulas 1 c, 2c, 3c, 4c and 5c In the compounds of the subformulae 1c, 2c, 3c, 4c and 5c, R 'has the meanings given for the compounds of the subformulae 1a to 5a and is preferably alkyl, alkoxy or alkenyl.

In addition to the preferred compounds of groups A, B and C, other compounds of formulas 1, 2, 3, 4 and 5 with other variants of the proposed substituents are also used. All of these substances are available by methods known from the literature or in analogy thereto.

In addition to compounds of the formula I according to the invention, the media according to the invention preferably comprise one or more compounds which are selected from groups A, B and / or C. The mass fractions of the compounds from these groups in the media according to the invention are preferably:

0 to 90%, preferably 20 to 90%, more preferably 30 to 90%;

 0 to 80%, preferably 10 to 80%, more preferably 10 to 65%;

0 to 80%, preferably 0 to 80%, more preferably 0 to 50%; wherein the sum of the mass fractions of the compounds of the groups A, B and / or C contained in the respective inventive media is preferably 5 to 90% and particularly preferably 10 to 90%.

The media according to the invention preferably contain 1 to 40%, particularly preferably 3 to 30%, of the compounds according to the invention.

The preparation of the liquid-crystal mixtures according to the invention is carried out in a conventional manner. In general, the desired amount of the components used in lesser amount in the main constituent components is dissolved, preferably at elevated

Temperature. It is also possible to use solutions of the components in an organic solvent, e.g. in acetone, chloroform or methanol, and to remove the solvent again after thorough mixing, for example by distillation. Furthermore, it is possible to

Mixtures in other conventional ways, eg. By using premixes, e.g. Homologous mixtures or using so-called "multi-bottle" systems produce.

The dielectrics may also contain further additives known to the person skilled in the art and described in the literature. For example, 0 to 15%, preferably 0 to 10%, pleochroic dyes, chiral

Dopants, stabilizers or nanoparticles can be added. The individual added compounds are used in concentrations of 0.01 to 6%, preferably from 0.1 to 3%. However, the concentration data of the other constituents of the liquid-crystal mixtures ie the liquid-crystalline or mesogenic compounds are given, without taking into account the concentration of these additives. The liquid-crystal mixtures according to the invention enable a significant expansion of the available parameter space.

The invention also electro-optical displays (in particular TFT displays with two plane-parallel support plates, which form a cell with a border, integrated non-linear elements for switching individual pixels on the carrier plates and one in the Cell-containing nematic liquid-crystal mixture having positive dielectric anisotropy and high resistivity) containing such media and the use of these media for electro-optical purposes.

The term "alkyl" embraces unbranched and branched alkyl groups having 1-15 carbon atoms, in particular the unbranched groups methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl and n-heptyl. Groups of 2-5 carbon atoms are generally preferred.

The term "alkenyl" includes unbranched and branched alkenyl groups having up to 15 carbon atoms, especially the unbranched groups. Particularly preferred alkenyl groups are C ₂ -C ₇ -1E-alkenyl, C ₄ -C ₇ 3E-alkenyl, C ₅ -C ₇ -alkenyl, C ₆ -C ₇ -5-alkenyl and C ₇ -6- Alkenyl, in particular C ₂ -C ₇ -1 E-alkenyl, C ₄ -C ₇ 3E-alkenyl and C ₅ -C ₇ -4-alkenyl. Examples of preferred alkenyl groups are vinyl, 1 E-propenyl,

1 E-butenyl, 1 E-pentenyl, 1 E-hexenyl, 1 E-heptenyl, 3-butenyl,

3E-pentenyl, 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4E-hexenyl,

5-hexenyl, 6-heptenyl and the like. Groups of up to 5

Carbon atoms are generally preferred.

The term "halogenated alkyl" preferably includes mono- or polyfluorinated and / or chlorinated radicals. Perhalogenated radicals are included. Particularly preferred are fluorinated alkyl radicals,

in particular CF ₃ , CH ₂ CF ₃ , CH ₂ CHF ₂ , CHF ₂ , CH ₂ F, CHFCF ₃ and

CF ₂ CHFCF ₃ . The term "halogenated alkenyl" and related expressions are explained accordingly.

The total amount of compounds of the formula I in the mixtures according to the invention is not critical. The mixtures may therefore contain one or more other components to optimize various properties.

The structure of the matrix display of polarizers, electrode base plates and electrodes with surface treatment according to the invention corresponds to the usual construction for such displays. It is the Concept of the usual construction here broadly and includes all modifications and modifications of the matrix display, in particular matrix display elements based on poly-Si TFT. However, a significant difference of the displays of the invention on the basis of the usual twisted nematic cell is the choice of the liquid crystal parameters of the liquid crystal layer.

The following examples illustrate the invention without limiting it. Those skilled in the art will be able to derive details of the embodiments from the examples, which are not detailed in the general description, to generalize them to general skill, and to apply them to a particular problem. Above and below, percentages are by weight. All temperatures are in degrees Celsius. Further, K = crystalline state, N = nematic phase, Sm = smectic phase (more specifically SmA, SmB, etc.), Tg = glass point and I = isotropic phase. The data between these symbols represent the transition temperatures. Δη means optical anisotropy (589 nm, 20 ° C), Δε the dielectric anisotropy (1 kHz, 20 ° C) and

the rotational viscosity (20 ° C, in the unit mPa-s).

The determination of physical, physicochemical or electro-optical parameters is carried out according to generally known methods, as described, inter alia, in the brochure "Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurements Methods", 1998, Merck KGaA, Darmstadt ,

The dielectric anisotropy Δε of the individual substances is determined at 20 ° C and 1 kHz. To this end, 5-10% by weight of the substance to be investigated is dissolved in the dielectrically positive mixture ZLI-4792 (Merck KGaA) and the measured value extrapolated to a concentration of 100%. The optical anisotropy Δη is at 20 ° C and a

Wavelength of 589.3 nm determines the rotational viscosity

at 20 ° C, both also by linear extrapolation. In the present application, unless expressly stated otherwise, the plural form of a term means both the singular form and the plural form, and vice versa. Other combinations of

 Embodiments and variants of the invention according to the description will become apparent from the appended claims or from

 Combinations of several of these claims.

Above and below, the abbreviations mean: ^lu DBB 4,4-di-tert-butylbiphenyl

 EE ethyl acetate

 n-Bul-n-butyllithium, solution in hexane

 MTB ether methyl tert-butyl ether

 5 PCC pyridinium chlorochromate

 THF tetrahydrofuran

 LiDBB lithium di-tert-butylbiphenyl

 RT room temperature

0 9 ^it - saturated

 least. distilled

Examples

 The present invention is not affected by the following

 5

 restrictive examples are described in detail.

Example 1: 4'-Ethyl 1- (4-propyl-cyclohex-1-enyl) -biphenyl

Step 1: 1 - (4-Bromophenyl) -4-propylcyclohexanol 5

A solution of 1, 4-dibromobenzene 1 (50 g, 212 mmol) in diethyl ether (950 mL) at -55 ° C with n-BuLi (145 mL of a 15% solution in n-hexane, 231 mmol). After 1 h, a solution of 4-propylcyclohexanone 2 (30 g, 214 mmol) in diethyl ether (50 mL) is added dropwise at -50 ° C. After a further hour, the batch is warmed to RT, with dist. Water and adjusted to pH 2 with hydrochloric acid (25%). The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sat. Sodium chloride solution, dried over sodium sulfate, filtered and concentrated in vacuo. The residue gives 1- (4-bromophenyl) -4-propylcyclohexanol 3 as a yellow clear oil.

Step 1 .2: 1 -Brom-4- (4-propyl-cyclohex-1-enyl) -benzene

A solution of 1 - (4-bromophenyl) -4-propyl-cyclohexanol 3 (67.7 g, 212 mmol) in toluene (300 mL) is treated with toluene-4-sulfonic acid monohydrate (2.0 g, 1: 1 mmol) and water Refluxed for 3 h. The reaction mixture is cooled to RT and washed with dist. Water and with 2N NaOH (15 mL). The aqueous phase is separated off and extracted with toluene. The combined organic phases are dried over sodium sulfate, filtered and concentrated. The residue is chromatographed on silica gel (heptane / chlorobutane 1: 1). Crystallization of the Crude product (n-heptane) gives 1-bromo-4- (4-propyl-cyclohex-1-enyl) -benzene 4 as a colorless solid.

Step 1 .3: 4'-Eth 1-4- (4-propylcyclohex-1-enyl) -biphenyl

1-Bromo-4- (4-propyl-cyclohex-1-enyl) -benzene 4 (30 g, 107 mmol) and 4-ethylphenylboronic acid 5 (17 g, 13 mmol) are initially charged in acetone (250 mL) and at 50 ° C with bis (dibenzylideneacetone) palladium (0) (70 mg, 0.12 mmol) and tris (o-tolyl) phosphine (210 mg, 0.69 mmol). Under reflux then 2N NaOH (107 mL, 215 mmol) is added dropwise. The reaction mixture is refluxed for 3 h, cooled to RT, distilled. Water (500mL) stirred and acidified with 2 N HCl. The precipitated product is filtered off with suction and purified by silica gel chromatography (heptane / toluene 1: 1). After crystallization (n-heptane), 4'-ethyl-4- (4-propyl-cyclohex-1-enyl) -biphenyl 6 is isolated in the form of colorless crystals.

Compound 6 shows the following phase behavior:

K 126 SmB 160 SmA 170 N 179 I

Δε = 3.1

Δη = 0.24

γι = 195 mPa-s

Example 2: 4'-Methyl-4- (4-vinyl-cyclohex-1-ene) biphenyl

Step 2.1: 4-Bromo-4'-methyl-biphenyl

A solution of 1-bromo-4-iodo-benzene 8 (100 g, 346 mmol) in toluene (550 mL) is added under nitrogen atmosphere with sodium carbonate (74 g, 13 mmol), dist. Water (310 ml_) and at about 70 ° C with

Tetrakis (triphenylphoshin) palladium (0) (12 g, 10 mmol) and then heated to boiling. Under reflux, a solution of p-toluene boronic acid 7 (47 g, 346 mmol) in ethanol (100 mL) is added rapidly. The reaction mixture is heated at reflux overnight and after cooling with dist. Water and toluene are added. The aqueous phase is extracted with toluene. The combined organic

Phases are dried over sodium sulfate, filtered and concentrated. The residue is chromatographed over silica gel (heptane / MTB ether 9: 1). 4-Bromo-4'-methyl-biphenyl 9 is isolated as a yellow, fine-crystalline solid.

Stage 2.2: (4-methoxymethylene-cyclohexyloxymethyl) benzene

MeOCHPPh ₃ CI

10

4-Benzyloxy-cyclohexanone 10 (50 g, 239 mmol) and methoxymethyltriphenylphosphonium chloride (100 g, 292 mmol) are initially charged in THF (600 mL). Potassium tert-butylate (41 g, 367 mmol) is added in portions, and the reaction mixture is stirred for 10 h at RT.

Then it is diluted with n-heptane, with dist. Water and sat. Washed sodium chloride solution and dried over sodium sulfate. The crude product is chromatographed on silica gel (heptane / MTB ether 8: 2). (4-Methoxymethylene cyclohexyloxynethyl) benzene 11 is obtained as a yellow oil. Benzyloxy-cyclohexanecarbaldehyde

A mixture of (4-methoxymethylene-cyclohexyloxymethyl) -benzene 11 (53 g, 201 mmol) and formic acid (170 mL) in toluene (600 mL) is stirred at RT for 24 h. After phase separation, the organic phase is washed with sat. Sodium bicarbonate solution was washed (2x), dried over sodium sulfate, filtered and concentrated in vacuo. 4-Benzyloxycyclohexanecarbaldehyde 12 is isolated as a yellow oil.

Stage 2.4: (4-vinylcyclohexyloxymethyl) benzene

4-Benzyloxy-cyclohexanecarbaldehyde 12 (32 g, 110 mmol) and methyl triphenylphosphonium bromide (47 g, 132 mmol) are initially charged in THF (230 mL). Potassium tert-butylate (19 g, 166 mmol) is added in portions, and the reaction mixture is stirred for 18 h at RT.

Then it is diluted with n-heptane, with dist. Water and sat. Washed sodium chloride solution and dried over sodium sulfate. The crude product is purified by silica gel chromatography (heptane / MTB ether 9: 1) to give (4-vinylcyclohexyloxymethyl) benzene 13 as a light yellow oil. Step 2.5: 4-vinyl-1-cyclohexanol

 13 14

In the first step, a mixture of DBB (80 g, 299 mmol) and lithium granules (2.1 g, 300 mmol) in THF (400 mL) is stirred under argon for 4 h. In the second step, a solution of (4-vinyl-cyclohexyloxymethyl) -benzene 13 (18 g, 75 mmol) in THF (700 mL) with cooling with

Magnesium bromide diethyl etherate (98 g, 373 mmol) was added. Subsequently, the LiDBB solution prepared in the first step is added dropwise at -75 ° C. The reaction mixture is stirred for 1 h, warmed to 0 ° C and treated with ice water cooling with bicarbonate solution and MTB ether. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sodium chloride solution, dried over sodium sulfate, filtered and concentrated in vacuo. The residue is purified by silica gel chromatography

(Dichloromethane / EE). 4-Vinylcyclohexanol 14 is isolated as a pale yellow oil.

Step 2.6: 4-Vin 1-cyclohexanone

 14 15

A mixture of PCC (15.6 g, 72 mmol) and Celite (15.6 g) in

Dichloromethane (85 mL) is added with slight cooling with a solution of 4-vinyl-cyclohexanol 14 (9.4 g, 72 mmol) in dichloromethane (85 mL) and stirred at RT for 10 h. The reaction mixture is filtered through silica gel, washed with dichloromethane and in vacuo concentrated. The residue obtained is 4-vinylcyclohexanone 15 in the form of a pale yellow oil.

Stage 2.7: 1 - 4'-Meth l-bi hen l-4 l -4-vin lc clohexanol

 9 15 16

A solution of 4-bromo-4'-methyl-biphenyl 9 (8.9 g, 31 mmol) in THF (150 ml) is treated at -70 ° C. with n-BuLi (20 ml of a 15% solution in n-hexane, 32 mmol) and stirred for 1 h. Then a solution of 4-vinylcyclohexanone 15 (4.0 g, 31 mmol) in THF (40 mL) is added dropwise at -60 ° C. After a further hour, the batch is warmed to RT, with dist. Water and adjusted to pH 2 with hydrochloric acid (25%). The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sodium chloride solution, dried over sodium sulfate, filtered and concentrated. 1 - (4'-Methyl-biphenyl-4-yl) -4-vinyl-cyclohexanol 16 is isolated as a brown oil. 'Methyl 4- (4-vinylcyclohex-1-enyl) biphenyl

 16 17

A solution of 1- (4'-methyl-biphenyl-4-yl) -4-vinylcyclohexanol 16

(10.2 g, 13 mmol) in dichloromethane (50 ml) at 0 ° C with triethylamine (5.6 mL, 40 mmol) and methanesulfonyl chloride (1 .4 mL, 17 mmol) and stirred for 18 h at RT. Subsequently, with n-heptane and dist.

Water is diluted, and the aqueous phase is separated. The

organic phase is chromatographed over silica gel (n-heptane).

Crystallization of the residue (isopropanol / acetone) and preparative HPLC (Acetone itril / water 95/5) gives 4'-methyl-4- (4-vinylcyclohex-1-enyl) biphenyl 17 as colorless crystals.

 Compound 17 shows the following phase behavior:

 K 177 (SmA 171) N 180 I

 Δε = 3.69

 Δη = 0.26

 γι = 189 mPa-s

Example 3: 4'-Methyl-4 - [(4-prop- (1E) -enyl) -cyclohex-1-enyl] -biphenyl

Step 3.1: 4-prop- (1E) -enyl-cyclohexanone

In the first step, a solution of 1-terf-butyl-5-ethylsulfonyltetrazole (16.4 g, 75 mmol) in ethylene glycol dimethyl ether (100 mL) at -60 ° C with a solution of potassium terf-butylate (9.7 g, 86 mmol). in THF (90 mL) and stirred for 30 min. In a separate apparatus is a

 Solution of 4-oxo-cyclohexanecarbaldehyde 18 (10 g, 75 mmol) in

 Ethylenglycoldimethylether (170 mL) at -70 ° C added dropwise with the solution prepared in the first step and stirred for 1 h. The

 Reaction mixture is warmed to 0 ° C and with dist. Water and MTB ether diluted. After phase separation, the organic phase is washed with dist. Water and sat. Sodium chloride solution washed and over

Dried sodium sulfate. The crude product is passed through silica gel Chromatography (1st dichloromethane, 2nd pentane / MTB ether 8: 2) and gives 4-prop- (1 E) -enyl-cyclohexanone 19 as a yellow oil.

Step 3.2: 1- (4'-methyl-biphenyl-4-yl) -4-prop- (1E) -enyl) -cyclohexanol

 20

 To a suspension of magnesium turnings (0.4 g, 16 mmol) in THF (3 mL) is added a solution of 4-bromo-4'-methyl-biphenyl 9 (4.0 g, 16 mmol) in

Carefully add THF (7 mL). The reaction mixture is boiled under reflux for 1 h, then slowly cooled to 30 ° C, with 4-prop- (1 E) -enyl-cyclohexanone 19 (4.6 g, 16 mmol) and stirred for a further 18 h at RT.

For working up with dist. Added water and acidified to pH 2 by addition of hydrochloric acid (25%). The aqueous phase is

separated and extracted with MTB ether. The combined organic phases are washed with sat. Sodium chloride solution washed over

Dried sodium sulfate, filtered and concentrated. 1 - (4'-Methyl-biphenyl-4-yl) -4-prop- (1E) -enyl-cyclohexanol 20 is isolated as a yellowish oil.

Step 3.3: 4'-Methyl-4 - [(4-prop- (1E) -enyl) -cyclohex-1-enyl] -biphenyl

A solution of 1- (4'-methyl-biphenyl-4-yl) -4-prop- (1E) -enyl-cyclohexanol 20 (6.6 g, 12 mmol) in dichloromethane (50 mL) is stirred at 0 ° C Triethylamine (5.0 mL, 36 mmol) and methanesulfonyl chloride (1 .2 mL, 15 mmol) were added. The reaction mixture is stirred for 18 h at RT and then washed with heptane and dist. Diluted with water. The aqueous phase is separated off and the organic phase is filtered through silica gel (heptane). The crude product is purified by crystallization (1st isopropanol / acetone, 2nd heptane / activated carbon) to give 4'-methyl-4 - [(4-prop- (1E) -enyl) -cyclohex-1-enyl] -biphenyl 21 as a colorless shimmering

Crystals.

 Compound 21 shows the following phase behavior:

K 161 (Sm? 160) SmA 180 N 209 I

Example 4: 4-4-But-3-enylcyclohex-1-enyl) -4'-methyl-biphenyl

Step 4.1: [4- (2-methoxyvinyl) cyclohexyloxymethyl] benzene

4-Benzyloxy-cyclohexanecarbaldehyde 12 (41.2 g, 183 mmol) and

Methoxymethyltriphenylphosphonium chloride (69.0 g, 200 mmol) are initially charged in THF (450 mL) and potassium tert-butoxide (25.6 g, 228 mmol) is added in portions at RT. The reaction mixture is stirred for 18 h and then diluted with heptane, with dist. Water and sat. Washed sodium chloride solution and dried over sodium sulfate. The crude product is purified by silica gel chromatography (heptane / MTB ether 9: 1) to give [4- (2-methoxyvinyl) -cyclohexyloxymethyl] -benzene 22 as a light yellow oil.

Step 4.2: 4-benzyloxy-cyclohexyl) -acetaldehyde

A mixture of [4- (2-methoxyvinyl) cyclohexyloxymethyl] benzene 22

(30.0 g, 108 mmol) and formic acid (82 mL, 2.2 mol) in toluene (300 mL) is stirred at RT for 24 h. After phase separation, the organic phase is washed with sat. Washed sodium bicarbonate solution, dried over sodium sulfate, filtered and concentrated in vacuo. (4-Benzyloxy-cyclohexyl) -acetaldehyde 23 is isolated as yellow oil.

Step 4.3: [4- (3-methoxyallyl) cyclohexyloxymethyl] benzene

 23

In analogy to stage 4.1, (4-benzyloxy-cyclohexyl) -acetaldehyde 23 is reacted with methoxymethyltriphenylphosphonium chloride in a Wittig reaction to give [4- (3-methoxyallyl) -cyclohexyloxymethyl] -benzene 24, which is isolated as a light yellow oil.

Stage 4.4: 3- (4-Benzyloxy-cyclohexyl) propionaldehyde

In analogy to stage 4.2, [4- (3-methoxyallyl) cyclohexyloxymethyl] benzene 24 is converted with formic acid by enol ether cleavage into 3- (4-benzyloxycyclohexyl) propionaldehyde 25, which is isolated as a yellow oil. -But-3-enyl-cyclohexyloxymethyl) -benzene

A mixture of 3- (4-benzyloxy-cyclohexyl) propionaldehyde 25 (21.3 g, 74 mmol) and methyltriphenylphosphonium chloride (29.2 g, 82 mmol) in THF (180 mL) is added in portions with potassium tert-butylate ( 10.0 g, 89 mmol) and stirred for 18 h. Then, by adding dist. Hydrolyzed, acidified with 2N hydrochloric acid and diluted with heptane. The organic phase is washed with dist. Water and sat.

Washed sodium chloride solution and dried over sodium sulfate. The crude product is purified by silica gel chromatography (heptane / MTB ether 8: 2) to give (4-but-3-enylcyclohexyloxymethyl) benzene 26 as a light yellow oil.

Step 4.6: 4-But-3-enylcyclohexanol

 26 27

In the first step, a mixture of DBB (38.0 g, 141 mmol) and lithium granules (1 .0 g, 144 mmol) in THF (200 mL) is stirred under argon for 4 h. In the second step, a solution of (4-but-3-enylcyclohexyloxymethyl) benzene 26 (11.16 g, 35 mmol) in THF (300 mL) under cooling with magnesium bromide diethyl etherate (46.5 g, 176 mmol). added. Subsequently, the LiDBB solution prepared in the first step is added dropwise at -75 ° C. The reaction mixture is stirred for 1 h, warmed to 0 ° C and treated with ice water cooling with bicarbonate solution and MTB ether. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sodium chloride solution, dried over sodium sulfate, filtered and concentrated in vacuo. The residue is purified by silica gel chromatography

(Dichloromethane / EE). 4-But-3-enylcyclohexanol 27 is isolated as a pale yellow oil.

Step 4.7: But-3-ene-1-cyclohexanone

A mixture of PCC (6.3 g, 29 mmol) and Celite (6.3 g) in

Dichloromethane (35 mL) is added with slight cooling with a solution of 4-but-3-enyl-cyclohexanol 27 (4.8 g, 29 mmol) in dichloromethane (30 mL) and stirred at RT for 10 h. The reaction mixture is filtered through silica gel, washed with dichloromethane and in vacuo concentrated. The residue obtained is but-3-enyl-cyclohexanone 28 in the form of a pale yellow oil.

Step 4.8: 4-But-3-enyl-1 - (4'-methyl-biphenyl-4-yl) -cyclohexanol

 9 28 29

0

 To a suspension of magnesium turnings (0.4 g, 18 mmol) in THF (2 mL), a solution of 4-bromo-4'-methyl-biphenyl 9 (4.4 g, 18 mmol) in THF (15 mL) is added carefully , The reaction mixture is boiled under reflux for 1 h, then slowly cooled to 30 ° C, with a * ->

 Solution of but-3-enyl-cyclohexanone 28 (2.8 g, 18 mmol) in THF (7 mL) and stirred for a further 18 h at RT.

 For working up with dist. Added water and acidified to pH 2 by addition of hydrochloric acid (25%). The aqueous phase is

0 separated and extracted with MTB ether. The combined organic phases are washed with sat. Sodium chloride solution washed over

 Dried sodium sulfate, filtered and concentrated. 4-But-3-enyl-1 - (4'-methyl-biphenyl-4-yl) -cyclohexanol 29 is isolated as a yellow-green oil.

5

 Stage 4.9: 4- (4-But-3-enyl-cyclohex-1-enyl) -4'-methyl-biphenyl

A solution of 4-but-3-enyl-1- (4'-methyl-biphenyl-4-yl) -cyclohexanol 29 (4.4 g, 9 mmol) in dichloromethane (30 mL) is treated at 0 ° C with triethylamine (3.7 mL, 27 mmol) and methanesulfonyl chloride (1 .0 mL, 13 mmol). The reaction mixture is stirred for 18 h at RT and then with Heptane and dest. Diluted with water. The aqueous phase is separated off and the organic phase is filtered through silica gel (heptane). The crude product is purified by crystallisation (1. Isopropanol / acetone, 2.

Heptane / acetone) to give 4- (4-but-3-enyl-cyclohex-1-enyl) -4'-methyl-biphenyl 30 as colorless shimmering crystals.

Compound 30 shows the following phase behavior:

K 99 SmE 133 SmB 159 SmA 181 N 192 I

Example 5: 4'-Methyl-4 - [(4-pent- (3E) -enyl) -cyclohex-1-enyl] -biphenyl-pent- (3E) -enyl) -cyclohexyloxymethyl] -benzene

A solution of 1-terf-butyl-5-ethylsulfonyltetrazole (21 .8 g, 100 mmol) in ethylene glycol dimethyl ether (100 ml) is treated at -60 ° C. with a solution of potassium tert-butylate (11.7 g, 105 mmol) in THF (15 mL) and stirred for 30 min. Subsequently, a solution of 3- (4-benzyloxy-cyclohexyl) -propionaldehyde 25 (27.8 g, 95 mmol) in

Ethylene glycol dimethyl ether (200 mL) was added dropwise at -70 ° C and stirred for 1 h. The reaction mixture is warmed to 0 ° C and with dist. Diluted water and MTB ether. After phase separation, the organic phase is washed with dist. Water and sat. Washed sodium chloride solution and dried over sodium sulfate. The crude product is purified by silica gel chromatography (heptane / MTB ether 9: 1) to give [(4-pent- (3E) -enyl) -cyclohexyloxymethyl] -benzene 31 as a clear, yellow oil.

Step 5.2: 4-Pent- (3E) -enyl-cyclohexanol

 31 32

In the first step, a mixture of DBB (84 g, 312 mmol) and lithium granules (2.2 g, 312 mmol) in THF (400 mL) is stirred under argon for 4 h. In the second step, a solution of [(4-pent- (3E) -enyl) cyclohexyloxymethyl] -benzene 31 (22 g, 78 mmol) in THF (600 mL) under cooling with magnesium bromide diethyl etherate (103 g, 391 mmol ). Subsequently, the LiDBB solution prepared in the first step is added dropwise at -75 ° C. The reaction mixture is stirred for 1 h, warmed to 0 ° C and treated with ice water cooling with bicarbonate solution and MTB ether. The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sodium chloride solution, dried over sodium sulfate, filtered and concentrated in vacuo. The residue is purified by silica gel chromatography

(Dichloromethane / EE). 4-Pent- (3E) -enyl-cyclohexanol 32 is isolated as a pale yellow oil.

Stage 5.3: 4-pent-3E) -enyl-cyclohexanone

 32 33

A mixture of PCC (22.2 g, 103 mmol) and Celite (22.5 g) in

Dichloromethane (120 mL) is added with slight cooling with a solution of 4-pent- (3E) -enyl-cyclohexanol 32 (16.0 g, 94 mmol) in dichloromethane (120 mL) and stirred at RT for 10 h. The reaction mixture is filtered through silica gel, washed with dichloromethane and concentrated in vacuo. The residue obtained is 4-pent- (3E) -enyl-cyclohexanone 33 in the form of a yellow oil.

Step 5.4: 1- (4'-Methyl-biphenyl-4-yl) -4-pent- (3E) -enyl-cyclohexanol

To a suspension of magnesium turnings (0.5 g, 21 mmol) in THF (2 mL), a solution of 4-bromo-4'-methyl-biphenyl 9 (5.3 g, 20 mmol) in THF (20 mL) is added carefully , The reaction mixture is boiled under reflux for 1 h, then slowly cooled to 30 ° C, treated with a solution of 4-pent- (3E) -enyl-cyclohexanone 33 (3.6 g, 21 mmol) in THF (8 mL) and another 18 Stirred at RT. For working up with dist. Added water and acidified to pH 2 by addition of hydrochloric acid (25%). The aqueous phase is separated and extracted with MTB ether. The combined organic phases are washed with sat.

Sodium chloride solution, dried over sodium sulfate, filtered and concentrated. 1 - (4'-Methyl-biphenyl-4-yl) -4-pent- (3E) -enyl-cyclohexanol 34 is isolated as a yellow-green oil.

A solution of 1- (4'-methyl-biphenyl-4-yl) -4-pent- (3E) -enyl-cyclohexanol 34 (6.7 g, 20 mmol) in dichloromethane (60 mL) is stirred at 0 ° C with triethylamine (8.3 mL, 60 mmol) and methanesulfonyl chloride (2.3 mL, 30 mmol). The reaction mixture is stirred for 18 h at RT and then washed with heptane and dist. Diluted with water. The aqueous phase is separated off and the organic phase is filtered through silica gel (heptane). The crude product is purified by crystallization (1st isopropanol / acetone, 2nd heptane) to give 4'-methyl-4 - [(4-pent- (3E) -enyl) -cyclohex-1-enyl] -biphenyl 35 as colorless shimmering crystals.

Compound 35 shows the following phase behavior:

K 120 Sm 154 SmA 180 N 197 1

Δε = 3.48

Δη = 0.25

γι = 709 mPa-s

Analog are produced:

 K127 Sm 140 SmE 153 SmA 170 N 189.9 I

Δε = 4.10

Δη = 0.25

 Sm 104 Sm 173 SmA 193 I

Claims

 P17125 ST.doc

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claims

1 . Compounds of the formula I,

wherein

 10

R ^{1 is} an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C 1 -C-

-CF ₂ O-, -OCF ₂ -, / \, ->"^ΟΟ">

· ^_S - _> -CO-O-, or -O-CO- should be replaced

 can be that O and S atoms are not directly linked to each other, and in which also one or more H atoms can be replaced by halogen, or H,

 20

 and an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, wherein in this radical also one or more

CH ₂ groups each independently of one another by -O-, -S-,

-CEC-, -CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

-CO-O-, or -O-CO- can be replaced so that

O- and S-atoms are not directly linked, and

In which one or more H atoms may also be replaced by halogen, or H,

where R ¹ and R ^{2 are} not simultaneously an alkyl chain having 1 to 15 C

35 atoms mean. Compounds according to Claim 1, characterized in that R ¹ denotes a halogenated or unsubstituted alkenyl radical having 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C 1 -C-,

CF ₂ O-, -OCF ₂ -, / \, ->"^ OO ^

-CO-O-, or -O-CO- can be replaced so that O and S atoms are not directly linked to one another, and in which also one or more H atoms can be replaced by halogen,

means.

Compounds according to claim 1 or 2, characterized in that

R ^{2 is} alkyl or alkenyl of up to 8 carbon atoms

means.

Compounds according to one or more of claims 1 to 3, characterized in that

R ^{1 is} an unbranched alkenyl group having 2 to 7 carbon atoms.

Compounds according to one or more of claims 1 to 4, characterized in that R ^{2 is} unbranched alkyl having 1 to 5 carbon atoms.

Compounds according to one or more of claims 1 to 5, characterized in that R ^{2 is} CH ₃ or CH ₂ CH ₃ .

Compounds according to one or more of claims 1 to 3, characterized in that R ^{2 is} unbranched alkenyl having 2 to 8 carbon atoms.

Compounds according to one or more of claims 1 to 7 selected from the following formulas, P17125 ST.doc

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 - 39 -

1-1

I-2

15

20

 wherein

 alkenyl is an alkenyl radical having 2 to 10 carbon atoms.

9. A process for the preparation of compounds of the formula I according to

 one or more of claims 1 to 8 comprising a

25

Process step in which a Arylnetallverbindung the formula

Wherein R ^{2 is} as defined for formula I, and

 M is Li, MgBr or MgCl, with a cyclohexanone compound of the formula

35 P17125 ST.doc

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 - 40 -

 wherein

R ^{1 is} as defined for formula I, and in a further reaction step comprising an elimination of the above

 Reaction step resulting OH function, to a compound of

10 Formula I

wherein the groups R ¹ and R ^{2 are} as defined in claim 1,

15

 is implemented.

10. Use of one or more compounds of the formula I according to one or more of claims 1 to 8 as a component in

20 a liquid-crystalline medium.

1 1. Liquid-crystalline medium containing at least two mesogenic compounds, characterized in that it contains at least one compound of the formula I.

wherein

R ^{1 is} an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, where in these radicals also one or more CH ₂ groups are each independently of one another by -C 1 -C-

-CF ₂ O-, -OCF ₂ -, / \, ->"^ ΟΟ ^>

 35

· - ° '· -CO-O-, or -O-CO- can be replaced so that O and S atoms are not directly with each other P17125 ST.doc

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 - 41 -

in which also one or more H atoms can be replaced by halogen, or H, and

R ^{2 is} an alkyl or alkenyl radical having 1 to 15 or 2 to 15 C atoms, wherein in this radical also one or more

CH ₂ groups each independently of one another by -O-, -S-,

 O and S atoms are not directly linked to one another, and in which also one or more H atoms may be replaced by halogen, or H,

 15

 mean, contains.

12. Use of the liquid-crystalline medium according to claim 1 1 for electro-optical purposes.

 20

 13. Electro-optical liquid crystal display containing a

 Liquid-crystalline medium according to Claim 1 1.

25

30

35