# Patent

## Title
Dibenzofuran derivatives, dibenzothiophene derivatives and fluorene derivatives

## Abstract

The present invention relates to compounds of the formula I




where

    Y, X1, X2, X3, R1, R2, A1, A2, Z1, Z2, m and n are as defined in Claim 1, to the use thereof as components in liquid-crystalline media, and to electro-optical display elements containing the liquid-crystalline media according to the invention.

## Background
The present invention relates to dibenzofuran, dibenzothiophene and fluorene derivatives, to liquid-crystalline media comprising these derivatives, and to electro-optical display elements containing these liquid-crystalline media. In particular, the invention relates to dibenzofuran, dibenzothiophene and fluorene derivatives of negative dielectric anisotropy.
Liquid crystals have found widespread use since the first commercially usable liquid-crystalline compounds were found about 30 years ago. Known areas of application are, in particular, displays for watches and pocket calculators, and large display panels as used in railway stations, airports and sports arenas. Further areas of application are displays of portable computers and navigation systems and video applications. For the last-mentioned applications in particular, high demands are made of the response times and contrast of the images.
The spatial arrangement of the molecules in a liquid crystal has the effect that many of its properties are direction-dependent. Of particular importance for use in liquid-crystal displays are the optical, dielectric and elasto-mechanical anisotropies. Depending on whether the molecules are oriented with their longitudinal axes perpendicular or parallel to the two plates of a capacitor, the latter has a different capacitance; in other words, the dielectric constant ε of the liquid-crystalline medium has different values for the two orientations. Substances whose dielectric constant is greater when the longitudinal axes of the molecules are oriented perpendicular to the capacitor plates than when they are oriented parallel are referred to as dielectrically positive. In other words, if the dielectric constant ε∥ parallel to the longitudinal axes of the molecules is greater than the dielectric constant ε195  perpendicular to the longitudinal axes of the molecules, the dielectric anisotropy Δε=ε∥−ε195  is greater than zero. Most liquid crystals used in conventional displays fall into this group.
Both the polarisability of the molecule and the permanent dipole moment play a role for the dielectric anisotropy. On application of a voltage to the display, the longitudinal axis of the molecules orients itself in such a way that the larger of the dielectric constants becomes effective. The strength of the interaction with the electric field depends on the difference between the two constants. In the case of small differences, higher switching voltages are necessary than in the case of large differences. The introduction of suitable polar groups, such as, for example, nitrile groups or fluorine, into the liquid-crystal molecules enables a broad range of working voltages to be achieved.
In the case of the liquid-crystalline molecules used in conventional liquid-crystal displays, the dipole moment oriented along the longitudinal axis of the molecules is larger than the dipole moment oriented perpendicular to the longitudinal axis of the molecules. In the most widespread TN (“twisted nematic”) cells, a liquid-crystalline layer with a thickness of only from about 5 to 10 μm is arranged between two plane-parallel glass plates, onto each of which an electrically conductive, transparent layer of tin oxide or indium tin oxide (ITO) has been vapour-deposited as electrode. A likewise transparent alignment layer, usually consisting of a plastic (for example polyimides), is located between these films and the liquid-crystalline layer. This alignment layer serves to bring the longitudinal axes of the adjacent liquid-crystalline molecules into a preferential direction through surface forces in such a way that, in the voltage-free state, they lie uniformly with the same orientation, flat or with the same small tilt angle, on the inside of the display surface. Two polarisation films which only enable linear-polarised light to enter and escape are applied to the outside of the display in a certain arrangement.
By means of liquid crystals in which the larger dipole moment is oriented parallel to the longitudinal axis of the molecule, very high-performance displays have already been developed. In most cases here, mixtures of from 5 to 20 components are used in order to achieve a sufficiently broad temperature range of the mesophase and short response times and low threshold voltages. However, difficulties are still caused by the strong viewing-angle dependence in liquid-crystal displays as are used, for example, for laptops. The best imaging quality can be achieved if the surface of the display is perpendicular to the viewing direction of the observer. If the display is tilted relative to the observation direction, the imaging quality deteriorates drastically under certain circumstances. For greater comfort, attempts are being made to maximise the angle through which the display can be tilted from the viewing direction of an observer without significantly reducing the imaging quality. Attempts have recently been made to improve the viewing-angle dependence using liquid-crystalline compounds whose dipole moment perpendicular to the longitudinal axis of the molecule is larger than that parallel to the longitudinal axis of the molecule. The dielectric anisotropy Δε is negative. In the field-free state, these molecules are oriented with their longitudinal axis perpendicular to the glass surface of the display. Application of an electric field causes them to orient themselves more or less parallel to the glass surfaces. In this way, it has been possible to achieve an improvement in the viewing-angle dependence. Displays of this type are known as VA-TFT (“vertically aligned”) displays.
Development in the area of liquid-crystalline materials is still far from complete. In order to improve the properties of liquid-crystalline display elements, attempts are constantly being made to develop novel compounds which enable optimisation of such displays.
WO 02/055463 A1 discloses, inter alia, 3-monosubstituted and 3,7-disubstituted 4,6-difluorodibenzofurans and -thiophenes, without giving precise details of the physical or electro-optical properties.
It is therefore an object of the present invention to provide compounds having advantageous properties for use in liquid-crystalline media. In particular, they should have negative dielectric anisotropy, which makes them particularly suitable for use in liquid-crystalline media for VA displays.
This object is achieved in accordance with the invention by compounds of the general formula I




in which:

    m and n are each, independently of one another, 0, 1, 2 or 3;
    Y denotes O, S, S(O), SO2, CH2, CF2, CCl2, CHF, CHCl, CFCl, C(CF3)2, CHCF3, C(CN)2 or CHCN;
    X1, X2 and X3 each, independently of one another, denote H, halogen, CN, SCN, NCS or SF5;
    A1 and A2 each, independently of one another, denote 1,4-phenylene, in which ═CH— may be replaced once or twice by ═N— and which may be unsubstituted or mono- to tetrasubstituted, independently of one another, by —CN, —F, —Cl, —Br, —I, C1-C6-alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine or by C1-C6-alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4-cyclohexadienylene, in which —CH2— may be replaced once or twice, independently of one another, by —O— or —S— in such a way that hetero atoms are not linked directly, and which may be unsubstituted or mono- or polysubstituted by —F, —Cl, —Br and/or —I;
    Z1 and Z2 each, independently of one another, denote a single bond, a double bond, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CF2CH2—, —CH2CF2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH2O—, —OCH2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C≡C—;
    R1 and R2 denote hydrogen, an alkanyl, alkoxy, alkenyl or alkynyl radical having 1 to 15 or 2 to 15 C atoms respectively which is unsubstituted, monosubstituted by —CN or —CF3 or monosubstituted or polysubstituted by —F, —Cl, —Br and/or —I, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by —O—, —S—, —SO2—, —CO—, —COO—, —OCO— or —O—CO—O— in such a way that hetero atoms are not linked directly, —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5;

where

    A1, A2, Z1, Z2, R1 and R2 may each have identical or different meanings if m or n is greater than 1;

and where,

in the case where simultaneously n=0, X1 denotes F, X2 denotes H or F and X3 denotes H, R2 then does not denote H.



The compounds have negative Δε and are therefore suitable, in particular, for use in VA-TFT displays. The compounds according to the invention preferably have a Δε of <−2 and particularly preferably a Δε of <−4. They exhibit very good compatibility with the usual substances used in liquid-crystal mixtures for displays.
Furthermore, the compounds of the formula I according to the invention have values for the optical anisotropy Δn which are particularly suitable for use in VA-TFT displays. The compounds according to the invention preferably have a Δn of greater than 0.05 and less than 0.40.
The other physical, physicochemical or electro-optical parameters of the compounds according to the invention are also advantageous for use of the compounds in liquid-crystalline media. The compounds or liquid-crystalline media comprising these compounds have, in particular, a sufficient breadth of the nematic phase and good low-temperature and long-term stability as well as sufficiently high clearing points.
It is preferred for Y to stand for oxygen, sulfur, CH2, CCl2 or CF2; in particular Y is an oxygen atom or CF2.
It is furthermore preferred for at least one of the radicals X1, X2 and X3 to denote halogen. Particularly preferably, at least two of the substituents X1, X2 and X3 denote halogen and the third denotes hydrogen or halogen. Very particularly preferably, all three radicals X1, X2 and X3 are halogen. Halogen here is in particular fluorine.
A1 and A2 are preferably and independently of one another an optionally substituted 1,4-phenylene, an optionally substituted 1,4-cyclohexylene, in which —CH2— may be replaced once or twice by —O—, or an optionally substituted 1,4-cyclohexenylene. If n or m is 2 or 3, the rings A1 and A2 may adopt identical or different meanings.
A1 and A2 are particularly preferably, independently of one another,




A1 and A2 are very particularly preferably 1,4-cyclohexylene rings and/or optionally fluorine-substituted 1,4-phenylene rings.

Z1 and Z2 are preferably, independently of one another, a single bond, —CH2O—, —OCH2—, —CF2O—, —OCF2—, —CF2CF2—, —CH═CH—, —CF═CH—, —CH═CF— or —CF═CF—, particularly preferably, independently of one another, a single bond, —CF2O—, —OCF2—, —CF2CF2—, —CH═CH—, —CF═CH—, —CH═CF— or —CF═CF—. Z1 and Z2 are very particularly preferably, independently of one another, a single bond, —CF2O—, —OCF2—, —CF2CF2— or —CF═CF—.
If R1 and R2 in the formula I each, independently of one another, represent an alkanyl radical and/or an alkoxy radical (alkyloxy radical) having 1 to 15 C atoms which is straight-chain or branched. Each of these radicals is preferably straight-chain, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is accordingly preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.
R1 and R2 in the formula I may each, independently of one another, also be an oxaalkyl radical, i.e. an alkanyl radical in which at least one of the non-terminal CH2 groups has been replaced by —O—, preferably straight-chain 2-oxapropyl(=methoxymethyl), 2-(=ethoxymethyl) or 3-oxabutyl(=methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl. In a corresponding manner, R1 and R2 in the formula I may also, independently of one another, be thioalkanyl or sulfonealkanyl radicals, i.e. alkanyl radicals in which one CH2 group has been replaced by —S— or —SO2—.
R1 and R2 in the formula I may furthermore each, independently of one another, be an alkenyl radical having 2 to 15 C atoms which is straight-chain or branched and has at least one C—C double bond. It is preferably straight-chain and has 2 to 7 C atoms. Accordingly, it is preferably vinyl, prop-1- or -2-phenyl, but-1-, -2- or -3-phenyl, pent-1-, -2-, -3- or -4-phenyl, hex-1-, -2-, -3-, -4- or -5-phenyl, or hept-1-, -2-, -3-, -4-, -5- or -6-phenyl. If the two C atoms of the C—C double bond are substituted, the alkenyl radical can be in the form of the E and/or Z isomer (trans/cis). In general, the respective E isomers are preferred.
In the same way as for an alkanyl radical, at least one of the CH2 groups in an alkenyl radical may also be replaced by oxygen, sulfur or —SO2—. In the case of replacement by —O—, an alkenyloxy radical (having a terminal oxygen) or an oxaalkenyl radical (having a non-terminal oxygen) is then present.
R1 and R2 in the formula I may also, independently of one another, be an alkynyl radical having 2 to 15 C atoms which is straight-chain or branched and has at least one C—C triple bond.
R1 and R2 in the formula I may each, independently of one another, be an alkanyl radical having 1 to 15 C atoms in which one CH2 group has been replaced by —O— and one has been replaced by —CO—, these preferably being adjacent. This thus contains an acyloxy group —CO—O— or an oxycarbonyl group —O—CO—. This radical is preferably straight-chain and has 2 to 6 C atoms. The following of these radicals are preferred here: acetoxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetoxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetoxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 2-acetoxypropyl, 3-propionyloxy-propyl, 4-acetoxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonyl-methyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2-(methoxy-carbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)propyl and 4-(methoxy-carbonyl)butyl. Furthermore, an alkanyl radical can also have an —O—CO—O— unit. Replacement of a CH2 group by only one —CO— group (carbonyl function) is also possible.
R1 and R2 in the formula I may each, independently of one another, be an alkenyl radical having 2 to 15 C atoms in which a CH2 group, preferably in the vicinity of an unsubstituted or substituted —C═C— unit, has been replaced by —CO—, —CO—O—, —O—CO— or —O—CO—O—, where this radical may be straight-chain or branched. The radical is preferably straight-chain and has 4 to 13 C atoms. Particular preference is given here to acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxy-pentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4-methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl AND 8-methacryloyloxy-octyl. Correspondingly, a CH2 group in the vicinity of a substituted —C≡C— unit in an alkynyl radical may also be replaced by —CO—, —CO—O—, —O—CO— or —O—CO—O—.
R1 and R2 in the formula I may each, independently of one another, be an alkanyl radical or alkoxy radical having 1 to 15 C atoms or an alkenyl radical or alkynyl radical having 2 to 15 C atoms, each of which is monosubstituted by —CN or —CF3, where these are preferably straight-chain. The substitution by —CN or —CF3 is possible in any desired position.
R1 and R2 in the formula I may each, independently of one another, be an alkanyl radical in which two or more CH2 groups have been replaced by —O— and/or —CO—O—, where this may be straight-chain or branched. It is preferably branched and has 3 to 12 C atoms.
R1 and R2 in the formula I may each, independently of one another, be an alkanyl radical or alkoxy radical having 1 to 15 C atoms or an alkenyl radical or alkynyl radical having 2 to 15 C atoms, each of which is monosubstituted or polysubstituted by F, Cl, Br and/or I, where these radicals are preferably straight-chain and halogen is preferably —F and/or —Cl. In the case of polysubstitution, halogen is preferably —F. The resultant radicals also include perfluorinated radicals, such as —CF3. In the case of mono-substitution, the fluorine or chlorine substituent can be in any desired position, but is preferably in the ω position.
R1 and R2 in the formula I may also each, independently of one another, be —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5.
R1 and R2 in the general formula I are particularly preferably, independently of one another, hydrogen or an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 C atoms respectively, where each of these radicals is preferably unsubstituted or monosubstituted or polysubstituted by halogen.
In connection with the present invention, halogen denotes fluorine, chlorine, bromine or iodine.
In connection with the present invention, the term “alkyl”—unless defined otherwise elsewhere in this description or in the claims—denotes a straight-chain or branched aliphatic hydrocarbon radical having 1 to 15 (i.e. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) carbon atoms. This radical is unsubstituted or monosubstituted or polysubstituted by fluorine, chlorine, bromine, iodine, carboxyl, nitro, —NH2, —N(alkanyl)2 and/or cyano, where the polysubstitution can take place with identical or different substituents. If this alkyl radical is a saturated radical, it is also referred to as “alkanyl”. Furthermore, the term “alkyl” also encompasses hydrocarbon radicals which are unsubstituted or correspondingly mono- or polysubstituted by identical or different substituents, in particular by —F, —Cl, —Br, —I and/or —CN or —CF3, and in which one or more CH2 groups may be replaced by —O— (“alkoxy”, “oxaalkyl”), —S— (“thioalkyl”), —SO2—, —CH═CH— (“alkenyl”), —C≡C— (“alkynyl”), —CO—O—, —O—CO— or —O—CO—O— in such a way that hetero atoms (O or S) in the chain are not linked directly to one another.
Preferred compounds of the general formula I have a total of zero, one, two or three units -Z1-A1- and/or -Z2-A2-, i.e. m+n=0, 1, 2 or 3 where m and n are each 0, 1, 2 or 3. If two or three units -Z1-A1- and/or -Z2-A2- are present, they may be bonded to only one side of the molecule (i.e. m=2 or 3 and n=0 or n=2 or 3 and m=0) or also to both sides of the molecule. Particularly preferably, m+n=0, 1 or 2.
Preferred compounds of the formula I for which m+n=0 are represented by the following formula:




in which R1, R2, X1, X2, X3 and Y have the same and the same preferred meanings as defined above for the formula I. In particular, Y stands for an oxygen atom or a CF2 group.

Preferred compounds of the formula I for which m+n=1 are represented by the following formulae:




in which R1, R2, A1, A2, X1, X2, X3, Z1, Z2 and Y have the same and the same preferred meanings as defined above for the formula I. In particular, Y stands for an oxygen atom or a CF2 group.

Preferred compounds of the formula I for which m+n=2 are represented by the following formulae:




in which R1, R2, A1, A2, X1, X2, X3, Z1, Z2 and Y have the same and the same preferred meanings as defined above for the formula I. If A1, A2, Z1 or Z2 occurs twice in the formulae Ie and If, they can in each case have identical or different meanings. In particular, Y stands for an oxygen atom or a CF2 group.

Preferred compounds of the formula I for which m+n=3 are represented by the following formulae:




in which R1, R2, A1, A2, X1, X2, X3, Z1, Z2 and Y have the same and the same preferred meanings as defined above for the formula I. If A1, A2, Z1 or Z2 occurs more than once in the formulae Ig to Ij, they can in each case have identical or different meanings. In particular, Y stands for an oxygen atom or a CF2 group.

Particular preference is given to compounds of the formulae Ia, Ib, Ic and Id according to the invention, in particular of the formulae Ia, Ib and Id.
Very particularly preferred compounds of the formula Ia are the following:







in which p and q are each, independently of one another, 1, 2, 3, 4, 5, 6, 7 or 8, and r and s are each, independently of one another, 2, 3, 4, 5, 6, 7 or 8, where the respective radicals are preferably straight-chain and one to four of the hydrogen atoms in each of the radicals may be replaced by fluorine, and Y stands for an oxygen atom or a CF2 group. Of the compounds of the formulae Ia-1 to Ia-12, those of the formulae Ia-1 to Ia-7 are still further preferred, in particular compounds of the formula Ia-1.

Of the preferred compounds of the formula Ib according to the invention, particular preference is given to the following:










in which R1, R2 and Y have the same and the same preferred meanings as defined above for the formula I. Very particularly preferably, R1 is an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively, R2 is hydrogen or an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively, and Y is an oxygen atom or a CF2 group.

Of the preferred compounds of the formula Id according to the invention, particular preference is given to the following:




in which R1, R2 and Y have the same and the same preferred meanings as defined above for the formula I. Very particularly preferably, R1 is an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively, R2 is hydrogen or an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively, and Y is an oxygen atom or a CF2 group. Of the compounds of the formulae Id-1 to Id-6, compounds of the formula Id-1 are the most preferred.

If radicals or substituents of the compounds according to the invention or the compounds according to the invention themselves exist as optically active or stereoisomeric radicals, substituents or compounds respectively since they have, for example, a centre of asymmetry, these are also encompassed by the present invention. It goes without saying here that the compounds of the general formula I according to the invention can exist in isomerically pure form, for example as pure enantiomers, diastereomers, E or Z isomers, trans or cis isomers, or as a mixture of a plurality of isomers in any desired ratio, for example as a racemate, E/Z isomer mixture or cis/trans isomer mixture.
The compounds of the general formula I are prepared by methods known per se, as described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and suitable for the said reactions. Use can be made here of variants which are known per se, but are not mentioned here in greater detail.
If desired, the starting materials can also be formed in situ by not isolating them from the reaction mixture, but instead immediately converting them further into the compounds of the general formula I.
The syntheses of various compounds of the general formula I according to the invention are described by way of example in the examples. The starting substances are obtainable by generally accessible literature procedures or are commercially available. The reactions described should be regarded as known from the literature.
The illustrative synthesis of a dibenzofuran according to the invention (Y=O, X1, X2 and X3=F, m and n=0, and R1 and R2=n-propyl) is shown below. The synthesis can be adapted to the compounds of the general formula I respectively desired through the choice of suitable starting materials. The individual synthesis steps should likewise be regarded as known from the literature.
Synthesis of the Boronic Acid 4:




Trifluorobenzene 1 is converted into the aldehyde 2 using butyllithium and N-formylpiperidine. After the subsequent Wittig reaction, a hydrogenation on a palladium catalyst is carried out. The trifluoropropylbenzene 3 is converted into the boronic acid 4 under standard conditions.
Synthesis of the Silyl Ether 8:




The aldehyde 5 is converted into the bromofluoropropylbenzene 6 by means of a Wittig reaction and subsequent hydrogenation on a platinum catalyst. The boronic acid ester obtained from lithium diisopropylamide (LDA) and trimethyl borate is converted into the phenol 7 analogously to a hydroboration. The OH function is converted into the silyl ether 8 using trimethylsilyl chloride (TMS-Cl) and imidazole.
Synthesis of the Dibenzofuran:




The silyl ether 8 is dissolved in toluene under nitrogen, and sodium carbonate, water and tetrakis(triphenylphosphine)palladium are added. A solution of the boronic acid 4 in absolute ethanol is slowly added to the reaction mixture at the boiling temperature. After boiling under reflux and cooling, the phases are separated. The aqueous phase is extracted with MTB ether. The organic phase is dried over sodium sulfate and evaporated. The residue is chromatographed on silica gel.




The silyl ether 9 is dissolved in THF, and dil. HCl is added. The solution is stirred at room temperature until conversion is complete. The solvent is subsequently removed, and the residue is taken up in dil. HCl solution and MTB ether. The aqueous phase is extracted three times with MTB ether. The organic phase is dried, evaporated and passed through silica gel.




The phenol 10 is dissolved in DMSO under nitrogen, a 60% sodium hydride/mineral oil suspension is added, and the mixture is warmed to 120° C. After 5 hours at this temperature, the cooled batch is added to dil. HCl solution. The aqueous phase is extracted with MTB ether. The organic phase is dried over sodium sulfate, evaporated and chromatographed on silica gel.
The illustrative synthesis of a fluorene derivative according to the invention (Y=CF2, X1, X2 and X3=F, m and n=0 and R1=ethoxy, R2=n-propyl) is shown below. The synthesis can be adapted to the compounds of the general formula I respectively desired through the choice of suitable starting materials. The individual synthesis steps should likewise be regarded as known from the literature.




A 2M solution of lithium diisopropylamide in cyclohexane/ethylbenzene/THF is added under nitrogen and at −70° C. to a solution of the aromatic compound 21 in THF. N-Formylpiperidine 22 is added to the batch. The batch is hydrolysed at 0° C. and acidified using hydrochloric acid. Work-up gives the aldehyde 23.




A 2M solution of lithium diisopropylamide in cyclohexane/ethylbenzene/THF is added under nitrogen and at −70° C. to a solution of the aromatic compound 24 in THF. The aldehyde 23, dissolved in THF, is added to the batch. The batch is hydrolysed and acidified using hydrochloric acid. Work-up gives the diphenylmethanol 25.




Under nitrogen, imidazole and the diphenylmethanol 25 are dissolved in DMF, trimethylsilyl chloride 26 is added, and the mixture is stirred overnight at room temperature. Work-up gives the silyl ether 27.




DMF is added under nitrogen to zinc, bistriphenylphosphinenickel(II) chloride, sodium bromide and triphenylphosphine, and the mixture is warmed to 80° C. After 30 minutes, the silyl ether 27, dissolved in DMF, is added dropwise to the batch. Work-up gives the fluorenol 28.




Pyridinium chlorochromate (PCC) is added under nitrogen to a suspension of Celite in dichloromethane. A solution of the fluorenol 28 in dichloromethane is subsequently added to the suspension. The batch is stirred overnight at room temperature. Work-up gives the fluorenone 29.




Boron trifluoride/diethyl ether complex is added under nitrogen and at −10° C. to a solution of the fluorenone 29 and ethanedithiol 30 in dichloromethane. The batch thaws overnight and is carefully added to sat. sodium hydrogencarbonate solution. The pH is adjusted to 8. Work-up gives the thioketal 31.




A solution of the thioketal 31 in dichloromethane is added under nitrogen and at a temperature of below −65° C. to a suspension of 1,3-dibromo-5,5-dimethylhydantoin in dichloromethane and a 65% solution of HF in pyridine. After 5 hours, the cooling is removed, and the batch is stirred overnight. The batch is subsequently added to ice-cooled 1N sodium hydroxide solution to which 19% sodium hydrogensulfite solution has been added. The pH is adjusted to 8. Work-up gives a mixture of the fluorenes 32a and 32b.




The fluorene mixture is dissolved in diethyl ether under nitrogen, and a 15% solution of butyllithium in n-hexane is added at −70° C. After 1 hour, a 1:1 THF/water mixture is added to the solution, and the batch is warmed to room temperature. Work-up gives the fluorene 32a.




A 15% solution of butyllithium in n-hexane is added under nitrogen and at −70° C. to a solution of the fluorene 32a in THF. N-Formylpiperidine 22 is added to the batch. The batch is hydrolysed and acidified using hydrochloric acid. Work-up gives the aldehyde 33.




A solution of potassium tert-butoxide in THF is added under nitrogen to a suspension of ethyltristriphenylphosphonium bromide in THF at 0° C. After 1 hour, the aldehyde 33, dissolved in THF, is slowly added. The batch is stirred overnight at room temperature, and water is subsequently added. Work-up gives the olefin 34.




The olefin 34 is dissolved in THF and hydrogenated on a palladium catalyst. The hydrogenation solution is evaporated. Work-up gives the pentafluorofluorene 35.
The reaction schemes shown should only be regarded as illustrative. The person skilled in the art can carry out corresponding variations of the syntheses described and also follow other suitable synthetic routes in order to obtain compounds of the formula I.
As already mentioned, the compounds of the general formula I can be used in liquid-crystalline media.
The present invention therefore also relates to a liquid-crystalline medium comprising at least two liquid-crystalline compounds, comprising at least one compound of the general formula I.
The present invention also relates to liquid-crystalline media comprising from 2 to 40, preferably from 4 to 30, components as further constituents besides one or more compounds of the formula I according to the invention. These media particularly preferably comprise from 7 to 25 components besides one or more compounds according to the invention. These further constituents are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of the azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, 1,3-dioxanes, 2,5-tetrahydropyrans, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl esters of cyclohexanecarboxylic acid, phenyl or cyclohexyl esters of cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, of cyclohexanecarboxylic acid or of cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-biscyclohexylbenzenes, 4′,4′-biscyclohexylbiphenyls, phenyl- or cyclohexyl-pyrimidines, phenyl- or cyclohexylpyridines, phenyl- or cyclohexyldioxanes, phenyl- or cyclohexyl-1,3-dithianes, 1,2-diphenylethanes, 1,2-dicyclohexyl-ethanes, 1-phenyl-2-cyclohexylethanes, 1-cyclohexyl-2-(4-phenylcyclohexyl)ethanes, 1-cyclohexyl-2-biphenylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzyl phenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be mono- or polyfluorinated.
The most important compounds suitable as further constituents of media according to the invention can be characterised by the formulae (II), (III), (IV), (V) and (VI):
















R′-L-E-R′′
(II)



R′-L-COO-E-R′′
(III)



R′-L-OOC-E-R′′
(IV)



R′-L-CH2CH2-E-R′′
(V)



R′-L-CF2O-E-R′′
(VI)










In the formulae (II), (III), (IV), (V) and (VI), L and E, which may be identical or different, each, independently of one another, denote a divalent radical from the group formed by -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -Thp-, -G-Phe- and -G-Cyc- and their mirror images, where Phe denotes unsubstituted or fluorine-substituted 1,4-phenylene, Cyc denotes trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr denotes pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio denotes 1,3-dioxane-2,5-diyl, Thp denotes tetrahydropyran-2,5-diyl and G denotes 2-(trans-1,4-cyclo-hexyl)ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.
One of the radicals L and E is preferably Cyc or Phe. 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 formulae (II), (III), (IV), (V) and (VI) in which L and E are selected from the group consisting of Cyc and Phe and simultaneously one or more components selected from the compounds of the formulae (II), (III), (IV), (V) and (VI) in which one of the radicals L and E is selected from the group consisting of Cyc and Phe and the other radical is selected from the group consisting of -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-, and optionally one or more components selected from the compounds of the formulae (II), (III), (IV), (V) and (VI) in which the radicals L and E are selected from the group consisting of -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-.
In a smaller sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), R′ and R′′ each, independently of one another, denote alkyl, alkenyl, alkoxy, alkoxyalkyl (oxaalkyl), alkenyloxy or alkanoyloxy having up to 8 C atoms. This smaller sub-group is called group A below, and the compounds are referred to by the sub-formulae (IIa), (IIIa), (IVa), (Va) and (VIa). In most of these compounds, R′ and R′′ are different from one another, one of these radicals usually being alkyl, alkenyl, alkoxy or alkoxy-alkyl (oxaalkyl).
In another smaller sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), which is known as group B, E denotes




In the compounds of group B, which are referred to by the sub-formulae (IIb), (IIIb), (IVb), (Vb) and (VIb), R′ and R′′ are as defined for the compounds of the sub-formulae (IIa) to (VIa) and are preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).
In a further smaller sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), R′′ denotes —CN. This sub-group is referred to below as group C, and the compounds of this sub-group are correspondingly described by sub-formulae (IIc), (IIIc), (IVc), (Vc) and (VIc). In the compounds of the sub-formulae (IIc), (IIIc), (IVc), (Vc) and (VIc), R′ is as defined for the compounds of the sub-formulae (IIa) to (VIa) and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).
Besides the preferred compounds of groups A, B and C, other compounds of the formulae (II), (III), (IV), (V) and (VI) having other variants of the proposed substituents are also customary. All these substances are obtainable by methods which are known from the literature or analogously thereto.
Besides the compounds of the general formula I according to the invention, the media according to the invention preferably comprise one or more compounds from groups A, B and/or C. The proportions by weight of the compounds from these groups in the media according to the invention are:

    group A:
    from 0 to 90%, preferably from 20 to 90%, in particular from 30 to 90%.
    group B:
    from 0 to 80%, preferably from 10 to 80%, in particular from 10 to 70%.
    group C:
    from 0 to 80%, preferably from 5 to 80%, in particular from 5 to 50%.


The media according to the invention preferably comprise from 1 to 40%, particularly preferably from 5 to 30%, of the compounds of the formula I according to the invention. Preference is furthermore given to media comprising more than 40%, in particular from 45 to 90%, of compounds of the formula I according to the invention. The media preferably comprise one, two, three, four or five compounds of the formula I according to the invention.
Examples of the compounds of the formulae (II), (III), (IV), (V) and (VI) are the compounds listed below:







where Ra and Rb, independently of one another, are —CpH2p+1 or —OCpH2p+1, and p=1, 2, 3, 4, 5, 6, 7 or 8, and L1 and L2, independently of one another, are —H or —F,





where m and n, independently of one another, are 1, 2, 3, 4, 5, 6, 7 or 8.

The media according to the invention are prepared in a manner conventional per se. In general, the components are dissolved in one another, preferably at elevated temperature. By means of suitable additives, the liquid-crystalline phases of the present invention can be modified in such a way that they can be used in all types of liquid-crystal display element that have been disclosed hitherto. Additives of this type are known to the person skilled in the art and are described in detail in the literature (H. Kelker/R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be used for the production of coloured guest-host systems or substances can be added in order to modify the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases.
Owing to their negative Δε, the compounds of the formula I are particularly suitable for use in VA-TFT displays.
The present invention therefore also relates to electro-optical liquid-crystal display elements containing a liquid-crystalline medium according to the invention.
The invention is explained in greater detail below with reference to working examples, but without being restricted thereby.
Above and below, Δn denotes the optical anisotropy (589 nm, 20° C.) and Δε denotes the dielectric anisotropy (1 kHz, 20° C.).
The Δε and Δn values of the compounds according to the invention are obtained by extrapolation from liquid-crystalline mixtures consisting of 10% of the respective compound according to the invention and 90% of the commercially available liquid-crystal mixture ZLI-2857 (for Δε) or ZLI-4792 (for Δn) (Merck KGaA, Darmstadt). In cases of limited solubility, the compound is measured in a mixture comprising only 5% of the compound, which is noted by the addition (5%) after the values in question.


EXAMPLES
The starting substances can be obtained by generally accessible literature procedures or are commercially available. The reactions described are known from the literature.
Example 1




7.0 g (22.9 mmol) of the silyl ether 8 are dissolved in 20 ml of toluene under nitrogen, and 5.0 g (49.3 mmol) of sodium carbonate, 10 ml of water and 175 mg (0.2 mmol) of tetrakis(triphenylphosphine)palladium are added. A solution of 5.0 g (22.9 mmol) of the boronic acid 4 in 10 ml of absolute ethanol is slowly added to the reaction mixture at the boiling temperature. After refluxing for 5 hours and cooling, the phases are separated. The aqueous phase is extracted with MTB ether. The organic phase is dried over sodium sulfate and evaporated. The residue is chromatographed on silica gel, giving 6.5 g of the silyl ether 9 (yield: 71%).




5.0 g (12.6 mmol) of the silyl ether 9 are dissolved in 40 ml of THF, and 10 ml of dil. HCl are added. The solution is stirred at room temperature until conversion is complete (TLC check). The solvent is subsequently removed, and the residue is taken up in 10 ml of dil. HCl solution and 20 ml of MTB ether. The aqueous phase is extracted three times with MTB ether. The organic phase is dried, evaporated and passed through silica gel, giving 3.7 g of the phenol 10 (yield: 90%).




3.0 g (9.2 mmol) of the phenol 10 are dissolved in 40 ml of DMSO under nitrogen, 736 mg (18.4 mmol) of a 60% sodium hydride/mineral oil suspension are added, and the mixture is warmed to 120° C. After 5 hours at this temperature, the cooled batch is added to dilute HCl solution. The aqueous phase is extracted with MTB ether. The organic phase is dried over sodium sulfate, evaporated and chromatographed on silica gel, giving 1.8 g of the dibenzofuran 11 (yield: 62%).

    Δε: −4.3
    Δn: 0.064


The following compounds according to the invention are obtained analogously to Example 1 using the corresponding precursors:
Examples 2 to 64
















 











Example No.
R1
R2
Δε
Δn














2
H
H




3
H
CH3


4
H
C2H5


5
H
n-C3H7


6
H
n-C4H9


7
H
n-C5H11


8
H
n-C6H13


9
H
n-C7H15


10
CH3
H


11
CH3
CH3


12
CH3
C2H5


13
CH3
n-C3H7


14
CH3
n-C4H9


15
CH3
n-C5H11


16
CH3
n-C6H13


17
CH3
n-C7H15


18
C2H5
H


19
C2H5
CH3


20
C2H5
C2H5


21
C2H5
n-C3H7


22
C2H5
n-C4H9


23
C2H5
n-C5H11


24
C2H5
n-C6H13


25
C2H5
n-C7H15


26
n-C3H7
H
−2.8
0.110


27
n-C3H7
CH3


28
n-C3H7
C2H5


29
n-C3H7
n-C4H9


30
n-C3H7
n-C5H11


31
n-C3H7
n-C6H13


32
n-C3H7
n-C7H15


33
n-C4H9
H


34
n-C4H9
CH3


35
n-C4H9
C2H5


36
n-C4H9
n-C3H7


37
n-C4H9
n-C4H9


38
n-C4H9
n-C5H11


39
n-C4H9
n-C6H13


40
n-C4H9
n-C7H15


41
n-C5H11
H


42
n-C5H11
CH3


43
n-C5H11
C2H5


44
n-C5H11
n-C3H7


45
n-C5H11
n-C4H9


46
n-C5H11
n-C5H11


47
n-C5H11
n-C6H13


48
n-C5H11
n-C7H15


49
n-C6H13
H


50
n-C6H13
CH3


51
n-C6H13
C2H5


52
n-C6H13
n-C3H7


53
n-C6H13
n-C4H9


54
n-C6H13
n-C5H11


55
n-C6H13
n-C6H13


56
n-C6H13
n-C7H15


57
n-C7H15
H


58
n-C7H15
CH3


59
n-C7H15
C2H5


60
n-C7H15
n-C3H7


61
n-C7H15
n-C4H9


62
n-C7H15
n-C5H11


63
n-C7H15
n-C6H13


64
n-C7H15
n-C7H15









Examples 65 to 128
















 











Example No.
R1
R2
Δε
Δn














65
H
H




66
H
CH3


67
H
C2H5


68
H
n-C3H7


69
H
n-C4H9


70
H
n-C5H11


71
H
n-C6H13


72
H
n-C7H15


73
CH3
H


74
CH3
CH3


75
CH3
C2H5


76
CH3
n-C3H7


77
CH3
n-C4H9


78
CH3
n-C5H11


79
CH3
n-C6H13


80
CH3
n-C7H15


81
C2H5
H
−7.8
0.149 (5%)


82
C2H5
CH3


83
C2H5
C2H5


84
C2H5
n-C3H7
−9.1
0.107 (5%)


85
C2H5
n-C4H9


86
C2H5
n-C5H11
−8.4
0.088


87
C2H5
n-C6H13


88
C2H5
n-C7H15


89
n-C3H7
H


90
n-C3H7
CH3


91
n-C3H7
C2H5


92
n-C3H7
n-C3H7


93
n-C3H7
n-C4H9


94
n-C3H7
n-C5H11


95
n-C3H7
n-C6H13


96
n-C3H7
n-C7H15


97
n-C4H9
H


98
n-C4H9
CH3


99
n-C4H9
C2H5


100
n-C4H9
n-C3H7


101
n-C4H9
n-C4H9


102
n-C4H9
n-C5H11


103
n-C4H9
n-C6H13


104
n-C4H9
n-C7H15


105
n-C5H11
H


106
n-C5H11
CH3


107
n-C5H11
C2H5


108
n-C5H11
n-C3H7


109
n-C5H11
n-C4H9


110
n-C5H11
n-C5H11


111
n-C5H11
n-C6H13


112
n-C5H11
n-C7H15


113
n-C6H13
H


114
n-C6H13
CH3


115
n-C6H13
C2H5


116
n-C6H13
n-C3H7


117
n-C6H13
n-C4H9


118
n-C6H13
n-C5H11


119
n-C6H13
n-C6H13


120
n-C6H13
n-C7H15


121
n-C7H15
H


122
n-C7H15
CH3


123
n-C7H15
C2H5


124
n-C7H15
n-C3H7


125
n-C7H15
n-C4H9


126
n-C7H15
n-C5H11


127
n-C7H15
n-C6H13


128
n-C7H15
n-C7H15









Examples 129 to 192




Examples 193 to 256
















 









Example No.
R1
R2





129, 193
H
H


130, 194
H
CH3


131, 195
H
C2H5


132, 196
H
n-C3H7


133, 197
H
n-C4H9


134, 198
H
n-C5H11


135, 199
H
n-C6H13


136, 200
H
n-C7H15


137, 201
CH3
H


138, 202
CH3
CH3


139, 203
CH3
C2H5


140, 204
CH3
n-C3H7


141, 205
CH3
n-C4H9


142, 206
CH3
n-C5H11


143, 207
CH3
n-C6H13


144, 208
CH3
n-C7H15


145, 209
C2H5
H


146, 210
C2H5
CH3


147, 211
C2H5
C2H5


148, 212
C2H5
n-C3H7


149, 213
C2H5
n-C4H9


150, 214
C2H5
n-C5H11


151, 215
C2H5
n-C6H13


152, 216
C2H5
n-C7H15


153, 217
n-C3H7
H


154, 218
n-C3H7
CH3


155, 219
n-C3H7
C2H5


156, 220
n-C3H7
n-C3H7


157, 221
n-C3H7
n-C4H9


158, 222
n-C3H7
n-C5H11


159, 223
n-C3H7
n-C6H13


160, 224
n-C3H7
n-C7H15


161, 225
n-C4H9
H


162, 226
n-C4H9
CH3


163, 227
n-C4H9
C2H5


164, 228
n-C4H9
n-C3H7


165, 229
n-C4H9
n-C4H9


166, 230
n-C4H9
n-C5H11


167, 231
n-C4H9
n-C6H13


168, 232
n-C4H9
n-C7H15


169, 233
n-C5H11
H


170, 234
n-C5H11
CH3


171, 235
n-C5H11
C2H5


172, 236
n-C5H11
n-C3H7


173, 237
n-C5H11
n-C4H9


174, 238
n-C5H11
n-C5H11


175, 239
n-C5H11
n-C6H13


176, 240
n-C5H11
n-C7H15


177, 241
n-C6H13
H


178, 242
n-C6H13
CH3


179, 243
n-C6H13
C2H5


180, 244
n-C6H13
n-C3H7


181, 245
n-C6H13
n-C4H9


182, 246
n-C6H13
n-C5H11


183, 247
n-C6H13
n-C6H13


184, 248
n-C6H13
n-C7H15


185, 249
n-C7H15
H


186, 250
n-C7H15
CH3


187, 251
n-C7H15
C2H5


188, 252
n-C7H15
n-C3H7


189, 253
n-C7H15
n-C4H9


190, 254
n-C7H15
n-C5H11


191, 255
n-C7H15
n-C6H13


192, 256
n-C7H15
n-C7H15









Examples 257 to 320




Examples 321 to 384
















 









Example No.
R1
R2





257, 321
H
H


258, 322
H
CH3


259, 323
H
C2H5


260, 324
H
n-C3H7


261, 325
H
n-C4H9


262, 326
H
n-C5H11


263, 327
H
n-C6H13


264, 328
H
n-C7H15


265, 329
CH3
H


266, 330
CH3
CH3


267, 331
CH3
C2H5


268, 332
CH3
n-C3H7


269, 333
CH3
n-C4H9


270, 334
CH3
n-C5H11


271, 335
CH3
n-C6H13


272, 336
CH3
n-C7H15


273, 337
C2H5
H


274, 338
C2H5
CH3


275, 339
C2H5
C2H5


276, 340
C2H5
n-C3H7


277, 341
C2H5
n-C4H9


278, 342
C2H5
n-C5H11


279, 343
C2H5
n-C6H13


280, 344
C2H5
n-C7H15


281, 345
n-C3H7
H


282, 346
n-C3H7
CH3


283, 347
n-C3H7
C2H5


284, 348
n-C3H7
n-C3H7


285, 349
n-C3H7
n-C4H9


286, 350
n-C3H7
n-C5H11


287, 351
n-C3H7
n-C6H13


288, 352
n-C3H7
n-C7H15


289, 353
n-C4H9
H


290, 354
n-C4H9
CH3


291, 355
n-C4H9
C2H5


292, 356
n-C4H9
n-C3H7


293, 357
n-C4H9
n-C4H9


294, 358
n-C4H9
n-C5H11


295, 359
n-C4H9
n-C6H13


296, 360
n-C4H9
n-C7H15


297, 361
n-C5H11
H


298, 362
n-C5H11
CH3


299, 363
n-C5H11
C2H5


300, 364
n-C5H11
n-C3H7


301, 365
n-C5H11
n-C4H9


302, 366
n-C5H11
n-C5H11


303, 367
n-C5H11
n-C6H13


304, 368
n-C5H11
n-C7H15


305, 369
n-C6H13
H


306, 370
n-C6H13
CH3


307, 371
n-C6H13
C2H5


308, 372
n-C6H13
n-C3H7


309, 373
n-C6H13
n-C4H9


310, 374
n-C6H13
n-C5H11


311, 375
n-C6H13
n-C6H13


312, 376
n-C6H13
n-C7H15


313, 377
n-C7H15
H


314, 378
n-C7H15
CH3


315, 379
n-C7H15
C2H5


316, 380
n-C7H15
n-C3H7


317, 381
n-C7H15
n-C4H9


318, 382
n-C7H15
n-C5H11


319, 383
n-C7H15
n-C6H13


320, 384
n-C7H15
n-C7H15









Examples 385 to 448




Examples 449 to 512
















 









Example No.
R1
R2





385, 449
H
H


386, 450
H
CH3


387, 451
H
C2H5


388, 452
H
n-C3H7


389, 453
H
n-C4H9


390, 454
H
n-C5H11


391, 455
H
n-C6H13


392, 456
H
n-C7H15


393, 457
CH3
H


394, 458
CH3
CH3


395, 459
CH3
C2H5


396, 460
CH3
n-C3H7


397, 461
CH3
n-C4H9


398, 462
CH3
n-C5H11


399, 463
CH3
n-C6H13


400, 464
CH3
n-C7H15


401, 465
C2H5
H


402, 466
C2H5
CH3


403, 467
C2H5
C2H5


404, 468
C2H5
n-C3H7


405, 469
C2H5
n-C4H9


406, 470
C2H5
n-C5H11


407, 471
C2H5
n-C6H13


408, 472
C2H5
n-C7H15


409, 473
n-C3H7
H


410, 474
n-C3H7
CH3


411, 475
n-C3H7
C2H5


412, 476
n-C3H7
n-C3H7


413, 477
n-C3H7
n-C4H9


414, 478
n-C3H7
n-C5H11


415, 479
n-C3H7
n-C6H13


416, 480
n-C3H7
n-C7H15


417, 481
n-C4H9
H


418, 482
n-C4H9
CH3


419, 483
n-C4H9
C2H5


420, 484
n-C4H9
n-C3H7


421, 485
n-C4H9
n-C4H9


422, 486
n-C4H9
n-C5H11


423, 487
n-C4H9
n-C6H13


424, 488
n-C4H9
n-C7H15


425, 489
n-C5H11
H


426, 490
n-C5H11
CH3


427, 491
n-C5H11
C2H5


428, 492
n-C5H11
n-C3H7


429, 493
n-C5H11
n-C4H9


430, 494
n-C5H11
n-C5H11


431, 495
n-C5H11
n-C6H13


432, 496
n-C5H11
n-C7H15


433, 497
n-C6H13
H


434, 498
n-C6H13
CH3


435, 499
n-C6H13
C2H5


436, 500
n-C6H13
n-C3H7


437, 501
n-C6H13
n-C4H9


438, 502
n-C6H13
n-C5H11


439, 503
n-C6H13
n-C6H13


440, 504
n-C6H13
n-C7H15


441, 505
n-C7H15
H


442, 506
n-C7H15
CH3


443, 507
n-C7H15
C2H5


444, 508
n-C7H15
n-C3H7


445, 509
n-C7H15
n-C4H9


446, 510
n-C7H15
n-C5H11


447, 511
n-C7H15
n-C6H13


448, 512
n-C7H15
n-C7H15









Examples 513 to 576




Examples 577 to 640
















 









Example No.
R1
R2





513, 577
H
H


514, 578
H
CH3


515, 579
H
C2H5


516, 580
H
n-C3H7


517, 581
H
n-C4H9


518, 582
H
n-C5H11


519, 583
H
n-C6H13


520, 584
H
n-C7H15


521, 585
CH3
H


522, 586
CH3
CH3


523, 587
CH3
C2H5


524, 588
CH3
n-C3H7


525, 589
CH3
n-C4H9


526, 590
CH3
n-C5H11


527, 591
CH3
n-C6H13


528, 592
CH3
n-C7H15


529, 593
C2H5
H


530, 594
C2H5
CH3


531, 595
C2H5
C2H5


532, 596
C2H5
n-C3H7


533, 597
C2H5
n-C4H9


534, 598
C2H5
n-C5H11


535, 599
C2H5
n-C6H13


536, 600
C2H5
n-C7H15


537, 601
n-C3H7
H


538, 602
n-C3H7
CH3


539, 603
n-C3H7
C2H5


540, 604
n-C3H7
n-C3H7


541, 605
n-C3H7
n-C4H9


542, 606
n-C3H7
n-C5H11


543, 607
n-C3H7
n-C6H13


544, 608
n-C3H7
n-C7H15


545, 609
n-C4H9
H


546, 610
n-C4H9
CH3


547, 611
n-C4H9
C2H5


548, 612
n-C4H9
n-C3H7


549, 613
n-C4H9
n-C4H9


550, 614
n-C4H9
n-C5H11


551, 615
n-C4H9
n-C6H13


552, 616
n-C4H9
n-C7H15


553, 617
n-C5H11
H


554, 618
n-C5H11
CH3


555, 619
n-C5H11
C2H5


556, 620
n-C5H11
n-C3H7


557, 621
n-C5H11
n-C4H9


558, 622
n-C5H11
n-C5H11


559, 623
n-C5H11
n-C6H13


560, 624
n-C5H11
n-C7H15


561, 625
n-C6H13
H


562, 626
n-C6H13
CH3


563, 627
n-C6H13
C2H5


564, 628
n-C6H13
n-C3H7


565, 629
n-C6H13
n-C4H9


566, 630
n-C6H13
n-C5H11


567, 631
n-C6H13
n-C6H13


568, 632
n-C6H13
n-C7H15


569, 633
n-C7H15
H


570, 634
n-C7H15
CH3


571, 635
n-C7H15
C2H5


572, 636
n-C7H15
n-C3H7


573, 637
n-C7H15
n-C4H9


574, 638
n-C7H15
n-C5H11


575, 639
n-C7H15
n-C6H13


576, 640
n-C7H15
n-C7H15









Example 641




220 ml (440 mmol) of a 2M solution of lithium diisopropylamide in cyclohexane/ethylbenzene/THF are added under nitrogen and at −70° C. to a solution of 77.2 g (400 mmol) of the aromatic compound 21 in 500 ml of THF. After 1.5 hours at the low temperature, 55.5 ml (500 mmol) of N-formylpiperidine 22 are added to the batch at −50° C. to −40° C. After 3 hours at −40° C., the batch is hydrolysed at 0° C. and acidified using hydrochloric acid. The aqueous phase is extracted with MTB ether, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate, evaporated and passed through silica gel (MTB ether/n-heptane 1:20), giving 72.1 g (81%) of the aldehyde 23.




16.1 ml (120 mmol) of a 2M solution of lithium diisopropylamide in cyclo-hexane/ethylbenzene/THF are added under nitrogen and at −70° C. to a solution of 24.0 g (110 mmol) of the aromatic compound 24 in 150 ml of THF. After 1.5 hours at the low temperature, 22.1 g (100 mmol) of the aldehyde 23, dissolved in 50 ml of THF, are added to the batch. After 3 hours at −70° C., the batch is warmed to room temperature, hydrolysed and acidified using hydrochloric acid. The aqueous phase is extracted with MTB ether, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate, evaporated and passed through silica gel (MTB ether/n-heptane 1:10), giving 40.2 g (83%) of the diphenyl-methanol 25.




Under nitrogen, 14.7 g (213 mmol) of imidazole and 35.0 g (79.5 mmol) of the diphenylmethanol 25 are dissolved in 100 ml of DMF, 14.4 ml of trimethylsilyl chloride 26 are added, and the mixture is stirred overnight at room temperature. Sat. sodium chloride solution is added to the batch, which is extracted with MTB ether. The organic phase is dried over sodium sulfate, evaporated and passed through silica gel (MTB ether/n-heptane 1:20), giving 37.9 g (93%) of the silyl ether 27.




200 ml of DMF are added under nitrogen to 12.4 g (189 mmol) of zinc, 19.6 g (30 mmol) of bistriphenylphosphinenickel(II) chloride, 18.5 g (180 mmol) of sodium bromide and 47.6 g (180 mmol) of triphenylphosphine, and the mixture is warmed to 80° C. After 30 minutes, 30.7 g (60 mmol) of the silyl ether 27, dissolved in 50 ml of DMF, are added dropwise to the batch. After 3 days, water is added to the cooled batch, which is extracted with MTB ether. The organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate and evaporated. The residue is taken up in THF, and conc. hydrochloric acid is added. After complete conversion (TLC), sat. sodium chloride solution is added to the batch, which is extracted with MTB ether. The organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate and evaporated. Chromatography (MTB ether/n-heptane 1:1) on silica gel gives 2.5 g (15%) of the fluorenol 28.




15 g of pyridinium chlorochromate (PCC) are added under nitrogen to a suspension of 40 g of Celite in 150 ml of dichloromethane. A solution of 10.0 g (35.6 mmol) of the fluorenol 28 in 25 ml of dichloromethane is subsequently added to the suspension. The batch is stirred overnight at room temperature. The Celite is separated off and washed with dichloro-methane. The organic phase is evaporated and passed through silica gel (MTB ether/n-heptane 1:3), giving 9.0 g (91%) of the fluorenone 29.




16.1 ml of boron trifluoride/diethyl ether complex are added under nitrogen and at −10° C. to a solution of 8.5 g (30.6 mmol) of the fluorenone 29 and 3.8 ml (45 mmol) of ethanedithiol 30 in 50 ml of dichloromethane. The batch thaws overnight and is carefully added to sat. sodium hydrogen-carbonate solution. The pH is adjusted to 8. The aqueous phase is extracted with dichloromethane, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate and evaporated. The residue is passed through silica gel (MTB ether/n-heptane 1:15), giving 9.6 g (89%) of the thioketal 31.




A solution of 9.0 g (25.4 mmol) of the thioketal 31 in 50 ml of dichloromethane is added under nitrogen and at a temperature of below −65° C. to a suspension of 28.6 g (100 mmol) of 1,3-dibromo-5,5-dimethylhydantoin in 150 ml of dichloromethane and 29.2 ml of a 65% solution of HF in pyridine. After 5 hours, the cooling is removed, and the batch is stirred overnight.
The batch is subsequently added to 1 l of ice-cooled 1N sodium hydroxide solution to which 35 ml of 19% sodium hydrogensulfite solution have been added. The pH is adjusted to 8. The aqueous phase is extracted with dichloromethane, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate, evaporated and passed through silica gel (MTB ether/n-heptane 1:30), giving 8 g of a mixture of the fluorenes 32a and 32b.




8 g of the fluorene mixture are dissolved in 50 ml of diethyl ether under nitrogen, and 15.7 ml (25.0 mmol) of a 15% solution of butyllithium in n-hexane are added at −70° C. After 1 hour, 10 ml of a 1:1 THF/water mixture are added to the solution, and the batch is warmed to room temperature. The batch is washed with sat. sodium chloride solution, dried over sodium sulfate and evaporated. The residue obtained is passed through silica gel (MTB ether/n-heptane 1:30), giving 5.3 g (70%, based on the preceding step) of the fluorene 32a.




10.7 ml (17.0 mmol) of a 15% solution of butyllithium in n-hexane are added under nitrogen and at −70° C. to a solution of 5.0 g (16.7 mmol) of the fluorene 32a in 75 ml of THF. After 1.5 hours at the low temperature, 2.2 ml (20 mmol) of N-formylpiperidine 22 are added to the batch at −50° C. to −40° C. After 3 hours at −40° C., the batch is hydrolysed at 0° C. and acidified using hydrochloric acid. The aqueous phase is extracted with MTB ether, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate, evaporated and passed through silica gel (MTB ether/n-heptane 1:15), giving 4.3 g (79%) of the aldehyde 33.




A solution of 1.7 g (15 mmol) of potassium tert-butoxide in 15 ml of THF is added under nitrogen to a suspension of 6.0 g (16.2 mmol) of ethyltris-triphenylphosphonium bromide in 30 ml of THF at 0° C. After 1 hour, the aldehyde 33, dissolved in 10 ml of THF, is added slowly, during which the batch temperature does not exceed 10° C. The batch is stirred overnight at room temperature, and water is subsequently added. The aqueous phase is extracted with MTB ether, and the organic phase is washed with sat. sodium chloride solution, dried over sodium sulfate and evaporated. The residue is passed through silica gel (MTB ether/n-heptane 1:15), giving 3.7 g (79%) of the olefin 34.




3.5 g (10.3 mmol) of the olefin 34 are dissolved in 40 ml of THF and hydrogenated on a palladium catalyst. The hydrogenation solution is evaporated. The residue obtained is passed through silica gel, giving 3.2 g (92%) of the pentafluorofluorene 35.
The following compounds according to the invention are obtained analogously to Example 641 using the corresponding precursors:
Examples 642 to 704




Examples 705 to 768
















 









Example No.
R1
R2





641, 705
C2H5
n-C3H7


642, 706
H
H


643, 707
H
CH3


644, 708
H
C2H5


645, 709
H
n-C3H7


646, 710
H
n-C4H9


647, 711
H
n-C5H11


648, 712
H
n-C6H13


649, 713
H
n-C7H15


650, 714
CH3
H


651, 715
CH3
CH3


652, 716
CH3
C2H5


653, 717
CH3
n-C3H7


654, 718
CH3
n-C4H9


655, 719
CH3
n-C5H11


656, 720
CH3
n-C6H13


657, 721
CH3
n-C7H15


658, 722
C2H5
H


659, 723
C2H5
CH3


660, 724
C2H5
C2H5


661, 725
C2H5
n-C4H9


662, 726
C2H5
n-C5H11


663, 727
C2H5
n-C6H13


664, 728
C2H5
n-C7H15


665, 729
n-C3H7
H


666, 730
n-C3H7
CH3


667, 731
n-C3H7
C2H5


668, 732
n-C3H7
n-C3H7


669, 733
n-C3H7
n-C4H9


670, 734
n-C3H7
n-C5H11


671, 735
n-C3H7
n-C6H13


672, 736
n-C3H7
n-C7H15


673, 737
n-C4H9
H


674, 738
n-C4H9
CH3


675, 739
n-C4H9
C2H5


676, 740
n-C4H9
n-C3H7


677, 741
n-C4H9
n-C4H9


678, 742
n-C4H9
n-C5H11


679, 743
n-C4H9
n-C6H13


680, 744
n-C4H9
n-C7H15


681, 745
n-C5H11
H


682, 746
n-C5H11
CH3


683, 747
n-C5H11
C2H5


684, 748
n-C5H11
n-C3H7


685, 749
n-C5H11
n-C4H9


686, 750
n-C5H11
n-C5H11


687, 751
n-C5H11
n-C6H13


688, 752
n-C5H11
n-C7H15


689, 753
n-C6H13
H


690, 754
n-C6H13
CH3


691, 755
n-C6H13
C2H5


692, 756
n-C6H13
n-C3H7


693, 757
n-C6H13
n-C4H9


694, 758
n-C6H13
n-C5H11


695, 759
n-C6H13
n-C6H13


696, 760
n-C6H13
n-C7H15


697, 761
n-C7H15
H


698, 762
n-C7H15
CH3


699, 763
n-C7H15
C2H5


700, 764
n-C7H15
n-C3H7


701, 765
n-C7H15
n-C4H9


702, 766
n-C7H15
n-C5H11


703, 767
n-C7H15
n-C6H13


704, 768
n-C7H15
n-C7H15

## Claims

1. A compound of formula I:




in which:
m and n are each, independently of one another, 0, 1, 2 or 3;
Y denotes O, S, S(O), SO2, CH2, CF2, CCl2, CHF, CHCl, CFCl, C(CF3)2, CHCF3, C(CN)2 or CHCN;
X1, X2 and X3 each, independently of one another, denote H, halogen, CN, SCN, NCS or SF5;
A1 and A2 each, independently of one another, denote 1,4-phenylene, in which ═CH— may be replaced once or twice by ═N— and which may be unsubstituted or mono- to tetrasubstituted, independently of one another, by —CN, —F, —Cl, —Br, —I, C1-C6-alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine or by C1-C6 -alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4-cyclohexadienylene, in which —CH2— may be replaced once or twice, independently of one another, by —O— or —S— in such a way that hetero atoms are not linked directly, and which may be unsubstituted or mono- or polysubstituted by —F, —Cl, —Br and/or —I;
Z1 and Z2 each, independently of one another, denote a single bond, a double bond, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CF2CH2—, —CH2CF2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH2O—, —OCH2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C═C—;
R1 and R2 denote an alkyl, alkoxy, alkenyl or alkynyl radical having 1 to 15 or 2 to 15 C atoms respectively which is unsubstituted, monosubstituted by —CN or —CF3 or monosubstituted or polysubstituted by F, Cl, Br and/or I, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by —O—, —S—, —SO2—, —CO—, —COO—, —OCO— or —OCO—O— in such a way that hetero atoms are not linked directly, —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5;

where
A1, A2, Z1, Z2, R1 and R2 may each have identical or different meanings if m or n is greater than 1; and where, in the case where m and n are both zero,
R1 and R2 are each, independently of one another, an unbranched alkyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively.

2. A compound according to claim 1, wherein
(m+n)is ≦3.

3. A compound according to claim 1, wherein Y═O or CF2.

4. A compound of formula I




in which:
m and n are each, independently of one another, 0, 1, 2 or 3;
Y denotes O, S, S(O), SO2, CH2, CF2, CCl2, CHF, CHCl, CFCl, C(CF3)2, CHCF3, C(CN)2 or CHCN;
wherein at least two of the substituents X1, X2 and X3 denote halogen and the third substituent denotes hydrogen or halogen,
A1 and A 2 each, independently of one another, denote 1,4-phenylene, in which ═CH— may be replaced once or twice by ═N— and which may be unsubstituted or mono- to tetrasubstituted, independently of one another, by —CN, —F, —Cl, —Br, —I, C1-C6-alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine or by C1-C6-alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4 -cyclohexadienylene, in which —CH2— may be replaced once or twice, independently of one another, by —O— or —S— in such a way that hetero atoms are not linked directly, and which may be unsubstituted or mono-or polysubstituted by —F, —Cl, —Br and/or —I;
Z1 and Z2 each, independently of one another, denote a single bond, a double bond, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CF2CH2—, —CH2CF2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH2O—, —OCH2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C≡C—;
R1 and R2 denote an alkyl, alkoxy, alkenyl or alkynyl radical having 1 to 15 or 2 to 15 C atoms respectively which is unsubstituted, monosubstituted by —CN or —CF3 or monosubstituted or polysubstituted by F, Cl, Br and/or I, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by —O—, —S—, —SO2—, —CO—, —COO—, —OCO— or —OCO—O— in such a way that hetero atoms are not linked directly, —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5;

where
A1, A2, Z1, Z2, R1 and R2 may each have identical or different meanings if m or n is greater than 1.

5. A compound according to claim 1, wherein
X1, X2 and X3 denote F.

6. A compound according to claim 1, wherein
Z1 and Z2, independently of one another, are a single bond,
—CF2O—, —OCF2—, —CF2CF2—, —CH═CH—, —CF═CH—, —CH═CF— or
—CF═CF—.

7. A compound according to claim 1, wherein
A1 and A2, independently of one another, are

8. A compound according to claim 1, wherein
R1 and R2 are each, independently of one another, an alkyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively, where each of these radicals is unsubstituted or monosubstituted or polysubstituted by halogen.

9. A compound according to claim 1, wherein
m and n are both zero; and
R1 and R2 are each, independently of one another, an unbranched alkyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively.

10. A compound according to at least one of claim 1, wherein m=1 and n=0;
A1 is





Z1 is a single bond, —CF2O—, —OCF2—, —CF2CF2—, —CH═CH—, —CF═CH—, —CH═CF— or —CF═CF—;
R1 is an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively; and
R2 is hydrogen or an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively.

11. A compound according to claim 1, wherein
m and n are 1;
A1 and A2 are both




Z1 and Z2 are a single bond;
R1 is an alkyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively; and
R2 is an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively.

12. A liquid-crystalline medium comprising at least two liquid-crystalline compounds, wherein at least one compound is one according to claim 1.

13. An electro-optical display element containing a liquid-crystalline medium according to claim 12.

14. A compound of formula I:




in which:
m and n are each, independently of one another, 0, 1, 2 or 3;
Y is CF2;
X1, X2 and X3 each, independently of one another, denote H, halogen, CN, SCN, NCS or SF5; at least two of X1, X2 and X3 are halogen,
A1 and A2 each, independently of one another, denote 1,4-phenylene, in which ═CH— may be replaced once or twice by ═N— and which may be unsubstituted or mono- to tetrasubstituted, independently of one another, by —CN, —F, —Cl, —Br, —I, C1-C6-alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine or by C1-C6 -alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4 -cyclohexadienylene, in which —CH2— may be replaced once or twice, independently of one another, by —O— or —S— in such a way that hetero atoms are not linked directly, and which may be unsubstituted or mono- or polysubstituted by —F, —Cl, —Br and/or —I;
Z1 and Z2 each, independently of one another, denote a single bond, a double bond, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CF2CH2—, —CH2CF2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH2O—, —OCH2—,—CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C═C—;
R1 and R2 denote hydrogen, an alkyl, alkoxy, alkenyl or alkynyl radical having 1 to 15 or 2 to 15 C atoms respectively which is unsubstituted, monosubstituted by —CN or —CF3 or monosubstituted or polysubstituted by F, Cl, Br and/or I, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by —O—, —S—, —SO2—, —CO—, —COO—, —OCO— or —OCO—O— in such a way that hetero atoms are not linked directly, —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5;
where
A1, A2, Z1, Z2, R1 and R2 may each have identical or different meanings if m or n is greater than 1;
and where,
in the case where simultaneously n is 0, X1 denotes F, X2 denotes H or F and X3 denotes H, R2 then does not denote H.

15. A compound of formula I:




in which:
m and n are each, independently of one another, 0, 1, 2 or 3;
Y denotes O, S, S(O), SO2, CH2, CF2, CCl2, CHF, CHCl, CFCl, C(CF3)2, CHCF3, C(CN)2 or CHCN;
X1, X2 and X3 each denote F;
A1 and A2 each, independently of one another, denote 1,4-phenylene, in which ═CH— may be replaced once or twice by ═N— and which may be unsubstituted or mono- to tetrasubstituted, independently of one another, by —CN, —F, —Cl, —Br, —I, C1-C6-alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine or by C1-C6 -alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4 -cyclohexadienylene, in which —CH2— may be replaced once or twice, independently of one another, by —O— or —S— in such a way that hetero atoms are not linked directly, and which may be unsubstituted or mono- or polysubstituted by —F, —Cl, —Br and/or —I;
Z1 and Z2 each, independently of one another, denote a single bond, a double bond, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CF2CH2—, —CH2CF2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH2O—, —OCH2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or
R1 and R2 denote hydrogen, an alkyl, alkoxy, alkenyl or alkynyl radical having 1 to 15 or 2 to 15 C atoms respectively which is unsubstituted, monosubstituted by —CN or —CF3 or monosubstituted or polysubstituted by F, Cl, Br and/or I, where, in addition, one or more CH2 groups in these radicals may each, independently of one another, be replaced by —O—, —S—, —SO2—, —CO—, —COO—, —OCO— or —OCO—O— in such a way that hetero atoms are not linked directly, —F, —Cl, —Br, —I, —CN, —SCN, —NCS or —SF5;

where
A1, A2, Z1, Z2, R1 and R2 may each have identical or different meanings if m or n is greater than 1.