DE19909760B4 - Benzofuran derivatives - Google Patents

Abstract

Benzofuran derivatives of the formula I R1- (A1-Z1) n-A2-Z2-WL1, L2 and L3 are each independently H or F, Y CF2, C = O, C = CF2 or CH-CHF2, X1 and X2, respectively independently of one another H, F, CN, an unsubstituted or substituted by one or more fluorine atoms straight or branched alkyl or alkoxy radical having 1 to 12 carbon atoms or an unsubstituted or substituted by one or more fluorine atoms straight-chain or branched alkenyl or Alkenyloxyrest with 2 to 12 C atoms, R1 H, an unsubstituted, a straight-chain or branched alkyl radical having 1 to 12 C atoms or alkenyl radical having 2 to 12 C atoms which is monosubstituted by CN or CF3 or at least monosubstituted by halogen, in which These radicals can also be replaced by one or more CH 2 groups independently of one another by -O-, -S-, -CO-, -CO-O-, -O-CO- or -O-CO-O- so that Heteroatoms are not directly linked, A1 and A2 are each independently each other is a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH 2 groups may be replaced by -O- and / or -S-, b) 1,4-cyclohexenylene radical, c) 1,4- Phenylene radical, in which also one or two CH groups may be replaced by N, d) radical from the group consisting of 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, naphthalene-2,6 -diyl, decahydronaphthalene-2,6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, wherein the radicals a), b) and c) may be substituted by CN, Cl or F, Z1 and Each Z 2 is independently -CO-O-, -O-CO-, -CH 2 O-, -OCH 2 -, -CH 2 CH 2 -, -CH = CH-, -C≡C- or a single bond and n is 0, 1 or 2 in which (a) at least one of L1 to L3 is F, or (b) X2 has a meaning other than H when X1 is unsubstituted alkyl or alkoxy and compounds are excluded wherein L1 and L2 are F, L3 and X2 H and X1 are H or unsubstituted alkyl.

Description

L¹, L² und L³ jeweils unabhängig voneinander H oder F,
Y CF₂, C=O, C=CF₂ oder CH-CHF₂,
X¹ und X² jeweils unabhängig voneinander H, F, CN, einen unsubstituierten oder einen durch ein oder mehrere Fluoratome substituierten geradkettigen oder verzweigten Alkyl- oder Alkoxyrest mit 1 bis 12 C-Atomen, oder einen unsubstituierten oder einen durch ein oder mehrere Fluoratome substituierten geradkettigen oder verzweigten Alkenyl- oder Alkenyloxyrest mit 2 bis 12 C-Atomen,
R¹ H, einen unsubstituierten, einen einfach durch CN oder CF₃ oder einen mindestens einfach durch Halogen substituierten geradkettigen oder verzweigten Alkylrest mit 1 bis 12 C-Atomen oder Alkenylrest mit 2 bis 12 C Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -O-, -S-,

-CO-, -CO-O-, -O-COoder -O-CO-O- so ersetzt sein können, daß Heteroatome nicht direkt miteinander verknüpft sind,
A¹ und A² jeweils unabhängig voneinander einen
a) trans-1,4-Cyclohexylenrest, worin auch eine oder mehrere nicht benachbarte CH₂-Gruppen durch -O- und/oder -S- ersetzt sein können,
b) 1,4-Cyclohexenylenrest,
c) 1,4-Phenylenrest, worin auch eine oder zwei CH-Gruppen durch N ersetzt sein können,
d) Rest aus der Gruppe 1,4-Bicyclo(2,2,2)-octylen, Piperidin-1,4-diyl, Naphthalin-2,6-diyl, Decahydronaphthalin-2,6-diyl und 1,2,3,4-Tetrahydronaphthalin-2,6-diyl,
wobei die Reste a), b) und c) durch CN, Cl oder F substituiert sein können,
Z¹ und Z² jeweils unabhängig voneinander -CO-O-, -O-CO-, -CH₂O-, -OCH₂-, -CH₂CH₂-, -CH=CH-, -C≡C- oder eine Einfachbindung
und
n 0, 1 oder 2
bedeuten,
wobei
(a) mindestens einer der Reste L¹ bis L³ F bedeutet, oder
(b) X² eine andere Bedeutung als H besitzt,
wenn X¹ ein unsubstituierter Alkyl- oder Alkoxyrest ist
und Verbindungen ausgeschlossen sind, worin L¹ und L² F, L³ und X² H und X¹ H oder unsubstituiertes Alkyl bedeuten.The invention relates to benzofuran derivatives of the formula I. R ¹ - (A ¹ -Z ¹ ) _n -A ² -Z ² -WI

L ¹ , L ² and L ^{3 are} each independently H or F,
Y CF ₂ , C = O, C = CF ₂ or CH-CHF ₂ ,
X ¹ and X ^{2 are} each independently H, F, CN, an unsubstituted or substituted by one or more fluorine atoms straight or branched alkyl or alkoxy radical having 1 to 12 carbon atoms, or an unsubstituted or substituted by one or more fluorine atoms straight-chain or branched alkenyl or alkenyloxy radical having 2 to 12 C atoms,
R ¹ H, an unsubstituted, a straight through CN or CF ₃ or at least one halogen-substituted straight-chain or branched alkyl radical having 1 to 12 carbon atoms or alkenyl radical having 2 to 12 C atoms, wherein in these radicals also one or more CH ₂ groups each independently of one another by -O-, -S-,

-CO-, -CO-O-, -O-COoder -O-CO-O- may be replaced so that heteroatoms are not directly linked to each other,
A ¹ and A ² each independently
a) trans-1,4-cyclohexylene radical, in which also one or more non-adjacent CH ₂ groups can be replaced by -O- and / or -S-,
b) 1,4-cyclohexenylene radical,
c) 1,4-phenylene radical, in which also one or two CH groups can be replaced by N,
d) radical from the group consisting of 1,4-bicyclo (2,2,2) octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl and 1,2,3 , 4-tetrahydronaphthalen-2,6-diyl,
where the radicals a), b) and c) can be substituted by CN, Cl or F,
Z ¹ and Z ^{2 are} each independently -CO-O-, -O-CO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CH = CH-, -C≡C- or a single bond
and
n 0, 1 or 2
mean,
in which
(A) at least one of the radicals L ¹ to L ^{3 is} F, or
(b) X ^{2 has} a meaning other than H,
when X ^{1 is} an unsubstituted alkyl or alkoxy radical
and compounds are excluded, wherein L ¹ and L ^{2 are} F, L ³ and X ^{2 are} H and X ^{1 is} H or unsubstituted alkyl.

The invention further relates to the use of these compounds of general formula I as components of liquid-crystalline media, which are preferably used for liquid-crystal and electro-optical display elements containing the liquid-crystalline media according to the invention.

The compounds of the formula I can be used as components 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) or the effect of based on dynamic dispersion. The substances used hitherto for this purpose always have certain disadvantages, for example too little stability against the action of heat, light or electric fields, unfavorable elastic and / or dielectric properties.

The invention had the object of finding new stable liquid-crystalline or mesogenic compounds which are suitable as components of liquid-crystalline media, in particular for TFT and STN displays.

It has now been found that the compounds of the formula I are particularly suitable as components of liquid-crystalline media. With their help, it is possible to obtain stable liquid-crystalline media, in particular suitable for TFT or STN displays. The new compounds are characterized by a high thermal stability and have advantageous values for the "holding ratio". In particular, the compounds of the formula I are distinguished by negative to very positive dielectric anisotropies Δε, average to extremely high optical anisotropies Δn and a favorable phase behavior.

With the provision of compounds of the formula I, the range of liquid-crystalline substances which are suitable for the production of liquid-crystalline mixtures from a variety of application-technical points of view is also broadly broader.

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 meaning of the formula I includes all isotopes of the chemical elements bound in the compounds of the formula I.

From the JP 07179856 For example, similar benzofuran-2,5-diyl compounds are known, but are preferably suitable for use in smectic mixtures.

From the DE 43 00 066 are fluorine-containing benzofurans and 2,3-dihydrobenzofurans known, but which are substituted in the 6-position by a radical containing at least one ring.

The compounds of the formula I are colorless in the pure state and form liquid-crystalline mesophases in a temperature range which is favorably located for the electro-optical use. Chemically, thermally and against light, they are stable.

The invention thus relates to the compounds of the formula I and the use of these compounds as components of liquid-crystalline media. The invention furthermore relates to liquid-crystalline media having at least two liquid-crystalline components, the liquid-crystalline media containing at least one compound of the formula I.

Above and below, R ¹ , A ¹ , Z ¹ , n, A ² , Z ² , L ¹ , L ² , L ³ , Y, X ¹ , X ² and W have the meaning given, unless expressly stated otherwise is.

For the sake of simplicity, in the following Cyc is a 1,4-cyclohexylene radical, Che is a 1,4-cyclohexenylene radical, Dio is a 1,3-dioxane-2,5-diyl radical, Dit is a 1,3-dithiane-2,5-diyl radical, Phe is a 1,4-phenylene radical, Pyd is a pyridine-2,5-diyl radical, Pyr is a pyrimidine-2,5-diyl radical and Bco is a bicyclo (2,2,2) -octylene radical, where Cyc and / or Phe are unsubstituted or - or may be substituted several times by Cl, F or CN.

The compounds of the formula I include compounds having three rings of the subformulae Ia and Ib: R ^I -A ² -W Ia R ¹ -A ² -Z ² -W Ib

Compounds with four rings of the subformulae Ic to If: R ¹ -A ¹ -A ² -W Ic R ¹ -A ¹ -A ² -Z ² -W Id R ¹ -A ¹ -Z ¹ -A ² W Ie R ¹ -A ¹ -Z ¹ -A ² -Z ² -W If as well as compounds with five rings of the subformulae Ig to In: R ¹ -A ¹ -A ¹ -A ² -W Ig R ¹ -A ¹ -Z ¹ -A ¹ A ² -W Ih R ¹ -A ¹ -A ¹ -Z ¹ -A ² -WIi R ¹ -A ¹ -A ¹ -A ² -Z ² -W Ij R ¹ -A ¹ -Z ¹ -A ¹ -Z ¹ -A ² -W Ik R ¹ -A ¹ -Z ¹ -A ¹ -A ² -Z ² -W Il R ¹ -A ¹ -A ¹ -Z ¹ -A ² -Z ² -W Im R ¹ -A ¹ -Z ¹ -A ¹ -Z ¹ -A ² -Z ² -W In

Of these, especially those of sub-formulas Ia, Ib, Ic, Id, Ie, Ig, Ih and Ii are preferred.

The preferred compounds of sub-formula Ia include those of sub-formulas Iaa and Iab: R ¹ -Phe-W Iaa R ¹ -Cyc-W Iab

The preferred compounds of sub-formula Ib include those of sub-formulas Iba and Ibb: R ¹ -Phe-Z ² -W Iba R ¹ -Cyc-Z ² -W Ibb

The preferred compounds of sub-formula Ic include those of sub-formulas Ica to Ici: R ¹ -Cyc-Cyc-W Ica R ¹ -Cyc-Phe-W Icb R ¹ -Phe-Phe-W Icc R ¹ -pyd-Phe-W icd R ¹ -Phe-Cyc-W Ice R ¹ -Dio-Phe-W Icf R ¹ -Pyr-Phe-W icg R ¹ -Cyc-Dio-W i R ¹ -Dio-Cyc-W Ici

Of these, those of the formulas Ica, Icb, Icc, Ice, I and Ici are particularly preferred.

The preferred compounds of partial formula Id include those of partial formulas Ida to Idg: R ¹ -Cyc-Cyc-Z ² -W Ida R ¹ -Cyc-Phe-Z ² -W idb R ¹ -Phe-Phe-Z ² -W Idc R ¹ -Pyr-Phe-Z ² -W Idd R ¹ -pyd-Phe-Z ² -W ide R ¹ -Cyc-Phe-CH ₂ CH ₂ -W Idf R ¹ -A ¹ -Phe-CH ₂ CH ₂ -W Idg

The preferred compounds of sub-formula Ie include those of sub-formulas Iea to Ieh: R ¹ -Cyc-Z ¹ -Cyc-W Iea R ¹ -A ¹ -CH ₂ CH ₂ -A ² -W Ieb R ¹ -Cyc-Z ¹ -Phe-W Iec R ¹ -A ¹ -OCO-Phe-W Ied R ¹ -Phe-Z ¹ -Phe-W Iee R ¹ -Pyr-Z ¹ -A ² -W Ief R ¹ -Pyd-Z ¹ -A ² -W Ieg R ¹ -Dio-Z ¹ -A ² W Ieh

Of these, those of the partial formulas Iea, Ieb, Iec and Iee are particularly preferred.

The preferred compounds of sub-formula If include those of sub-formulas Ifa to Ife: R ¹ -Phe-CH ₂ CH ₂ -A ² -Z ² -W Ifa R ¹ -A ¹ -COO-Phe-Z ² -W Ifb R ¹ -Cyc-Z ¹ -Cyc-Z ² -W Ifc R ¹ -Phe Z ¹ -Phe Z ² -W Ifd R ¹ -Cyc-CH ₂ CH ₂ -Phe-Z ² -W Ife

The preferred compounds of sub-formulas Ig to In include those of sub-formulas Io to Iv: R ¹ -A ¹ -Cyc-Cyc-W Io R ¹ -A ¹ -Cyc-Phe-W Ip R ¹ -A ¹ -CH ₂ CH ₂ -A ¹ -Phe-W Iq R ¹ -Cyc-Z ¹ -A ¹ -Z ¹ -Phe-W Ir R ¹ -Phe-Phe-Phe-W Is R ¹ -Phe-Z ¹ -A ¹ -Phe-W It R ¹ -A ¹ -Phe Z ¹ -Phe W Iu R ¹ -A ¹ -Z ¹ -Cyc-Phe-Z ² -W Iv

In the compounds of the formulas above and below, R ^{1 is} preferably alkyl or alkenyl, furthermore preferably alkoxy. R ¹ is particularly preferably a straight-chain unsubstituted alkyl radical or a straight-chain unsubstituted alkenyl radical. Among the alkenyl radicals, vinyl and the 1E and 3E alkenyl radicals are preferred.

A ¹ and A ² independently of one another are preferably Phe, Cyc, Che, Pyd, Pyr or Dio. The compounds of the formula I preferably contain no more than one of the radicals Bco, Pyd, Pyr, Dio or Dit.

If the ring A ¹ exists twice, the two rings can have the same or different meanings. The same applies to the bridge Z ¹ .

A ¹ and / or A ² preferably each independently of one another are trans-1,4-cyclohexylene or 1,4-phenylene monosubstituted or disubstituted by F or CN. Particularly preferably, A ¹ and / or A ²

oder

n ist vorzugsweise 0 oder 1.Most preferably, A ¹ and / or A ^{2 are} each independently

or

n is preferably 0 or 1.

Z ¹ and Z ² independently of one another are preferably -CH ₂ CH ₂ -, -CO-O-, -O-CO- or a single bond, especially preferably -CO-O-, -O-CO- or a single bond and very extraordinarily preferably a single bond.

In a particularly preferred embodiment, n is 0 and Z ^{2 is} -CO-O-, -O-CO- or a single bond or n 1 and Z ¹ and Z ^{2 are} a single bond.

In the structural element W, Y is preferably CO, CF ₂ or C = CF ₂ , particularly preferably Y is CO.

X ¹ is preferably H, F, CN, an unsubstituted or substituted by one or more fluorine atoms alkyl radical.

X ² is preferably H, F or CN, in particular H or F.

p = 0 bis 6The formulas (1) to (9) represent preferred meanings of the structural element W.

p = 0 to 6

In a preferred embodiment, X ^{1 is} F or CN and at least one of L ¹ to L ³ is F or X ² has a meaning other than H.

In another preferred embodiment, X ^{1 is} an unsubstituted alkenyl or alkenyloxy radical or an alkyl, alkoxy, alkenyl or alkenyloxy radical substituted by one or more fluorine atoms and at least one of L ¹ to L ³ is F or X ² is another Meaning as H.

Particularly preferred meanings of the structural element W are the formulas (2a) and (4a):

If R ¹ in the formulas above and below denotes an alkyl radical or an alkoxy radical, this may be straight-chain or branched. Preferably, it is straight-chain, has 2, 3, 4, 5, 6 or 7 carbon atoms and thus preferably ethyl, propyl, butyl, pentyl, hexyl, heptyl, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy, furthermore methyl , Octyl, nonyl, decyl, undecyl, dodecyl, methoxy, octoxy, nonoxy, decoxy or undecoxy.

If X ¹ and / or X ² each, independently of one another, in the formulas above and below represent an alkyl radical or an alkoxy radical, these may be straight-chain or branched. They are preferably straight-chain, have 1, 2, 3, 4, 5, 6 or 7 carbon atoms and accordingly preferably represent methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, Hexoxy or heptoxy, furthermore octyl, nonyl, decyl, undecyl, dodecyl, octoxy, nonoxy, decoxy, undoxy or dodecoxy.

If R ^{1 is} oxaalkyl, this radical is preferably straight-chain 2-oxapropyl (= methoxymethyl), 2 - (= ethoxymethyl) or 3-oxabutyl (= 2-methoxyethyl), 2-, 3- or 4-oxapentyl, 2-, 3-, 4- or 5-oxahexyl, 2-, 3-, 4-, 5- or 6-oxaheptyl, 2-, 3-, 4-, 5-, 6- or 7-oxaoctyl, 2-, 3- , 4-, 5-, 6-, 7- or 8-oxanonyl, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-oxadecyl.

If R ¹ , X ¹ and / or X ^{2 are} each independently an alkenyl radical, these may be straight-chain or branched. Preferably, they are straight-chain and have 2 to 10 carbon atoms. Accordingly, they mean in particular vinyl, prop-1 or prop-2-enyl, but-1, 2- or but-3-enyl, pent-1, 2-, 3- or pent-4-enyl, hexyl 1-, 2-, 3-, 4- or hex-5-enyl, hept-1, 2-, 3-, 4-, 5- or hept-6-enyl, Oct-1, 2-, 3 , 4-, 5-, 6- or oct-7-enyl, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyl, Dec-1 , 2-, 3-, 4-, 5-, 6-, 7-, 8-, or dec-9-enyl.

If R ¹ , X ¹ and / or X ² each independently represent an alkenyloxy radical, these may be straight-chain or branched. Preferably, they are straight-chain and have 2 to 10 carbon atoms. Accordingly, they mean particularly vinyloxy, prop-1- or prop-2-enyloxy, but-1-, 2- or but-3-enyloxy, pent-1-, 2-, 3- or pent-4-enyloxy, hexane 1-, 2-, 3-, 4- or hex-5-enyloxy, hept-1, 2-, 3-, 4-, 5- or hept-6-enyloxy, Oct-1, 2-, 3 , 4-, 5-, 6- or oct-7-enyloxy, non-1-, 2-, 3-, 4-, 5-, 6-, 7- or non-8-enyloxy, Dec-1 , 2-, 3-, 4-, 5-, 6-, 7-, 8- or dec-9-enyloxy.

If R ^{1 is} an alkyl radical in which one CH ₂ group has been replaced by -O- and one by -CO-, these groups are preferably adjacent. Thus, this group includes an acyloxy group -CO-O- or an oxy-carbonyl group -O-CO-. It is preferably straight-chain and has 2 to 6 C atoms. It therefore particularly means acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 3-acetyloxypropyl, 3-propionyloxypropyl, 4-acetyloxybutyl, methoxycarbonyl, ethoxycarbonyl, Propoxycarbonyl, butoxycarbonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2- (methoxycarbonyl) ethyl, 2- (ethoxycarbonyl) ethyl, 2- (propoxycarbonyl) ethyl, 3- (methoxycarbonyl) propyl, 3- (ethoxycarbonyl) propyl or 4 - (methoxycarbonyl) butyl.

If R ^{1 is} an alkenyl radical in which one of the double bond adjacent CH ₂ group is replaced by -CO- or -CO-O- or -O-CO-, this may be straight-chain or branched. It is preferably straight-chain and has 4 to 12 C atoms. It therefore particularly means acryloyloxymethyl, 2-acryloyloxyethyl, 3-acryloyloxypropyl, 4-acryloyloxybutyl, 5-acryloyloxypentyl, 6-acryloyloxyhexyl, 7-acryloyloxyheptyl, 8-acryloyloxyoctyl, 9-acryloyloxynonyl, methacryloyloxymethyl, 2-methacryloyloxyethyl, 3-methacryloyloxypropyl, 4- Methacryloyloxybutyl, 5-methacryloyloxypentyl, 6-methacryloyloxyhexyl, 7-methacryloyloxyheptyl or 8-methacryloyloxyoctyl.

If R ^{1 is} a monosubstituted by CN or CF ₃ is substituted alkyl or alkenyl radical, this radical is preferably straight-chain and the substitution by CN or CF ₃ in ω-position.

If R ^{1 is} an alkyl or alkenyl radical which is at least monosubstituted by halogen, this radical is preferably straight-chain and halogen is preferably F or Cl. In the case of multiple substitution, halogen is preferably F. The resulting radicals also include perfluorinated radicals. For single substitution, the fluoro or chloro substituent may be in any position, but preferably in the ω position.

If X ¹ and / or X ² represent an substituted by one or more F atoms substituted alkyl, alkoxy, alkenyl or alkenyloxy radical, in each case independently of one another, so these may be straight or branched. Preferably, they are straight-chain and have 1 to 8 and more preferably 1 to 4 carbon atoms. In this case, X ¹ mean and / or X ² are each independently of one another particularly preferably CHF _2, CF _3, OCHF _2, OCF _3, CHFCF _3, CF ₂ CHF _2, OCH ₂ CHF _2, OCH ₂ CF _3, OCHFCF _3, OCF ₂ CHF ₂ , OC ₂ F ₅ , CH = CHF, CH = CF ₂ , CF = CF ₂ , OCH = CF ₂ , OCF = CF ₂ , C ₂ H ₄ CHF ₂ , CF ₂ CH ₂ CF ₃ , OCH ₂ CF ₂ CHF ₂ , OCH ₂ C ₂ F ₅ , OCF ₂ CHFCF ₃ , OCF = CFCF ₃ , O (CH ₂ ) ₃ CF ₃ , OCH ₂ C ₃ F ₇ or OCF = CF-C ₂ F ₅ and most preferably CHF ₂ , CF ₃ , OCHF ₂ , OCF ₃ , OCHFCF ₃ , OC ₂ F ₅ or OCH = CF ₂ .

Compounds of the formula I having a branched wing group R ¹ , X ¹ and / or X ² may occasionally be of importance for better solubility in the usual liquid-crystalline base materials, but especially as chiral dopants if they are optically active. Smectic compounds of this type are useful as components of ferroelectric materials. However, the optically inactive compounds of the formula I are preferred.

Branched groups of this type usually contain no more than one chain branch. Preferred branched radicals R ¹ , X ¹ and / or X ² are isopropyl, 2-butyl (= 1-methylpropyl), isobutyl (= 2-methylpropyl), 2-methylbutyl, isopentyl (= 3-methylbutyl), 2-methylpentyl, 3-methylpentyl, 2-ethylhexyl, 2-propylpentyl, isopropoxy, 2-methylpropoxy, 2-methylbutoxy, 3-methylbutoxy, 2-methylpentoxy, 3-methylpentoxy, 2-ethylhexoxy, 1-methylhexoxy, 1-methylheptoxy.

Formula I includes both the racemates of these compounds and the optical antipodes and mixtures thereof.

Preferred among these compounds of the formula I and the sub-formulas are those in which at least one of the radicals contained therein has one of the preferred meanings given.

In the compounds of formula I those stereoisomers are preferred in which the rings Cyc and piperidine are trans-1,4-disubstituted. Those of the above formulas containing one or more groups Pyd, Pyr and / or Dio each include the two 2,5-position isomers.

L^a, L^b, L^c, L^c = jeweils unabhängig voneinander H oder F.Some very particularly preferred smaller groups of compounds of the formula I are those of the partial formulas I1 to I11:

L ^a , L ^b , L ^c , L ^c = each independently of one another H or F.

L^b, L^c = jeweils unabhängig voneinander H oder F.Particularly preferred formulas from the group of the sub-formulas I1 to I11 are the formulas I1, I4, I5 and I10. Among the formulas I4 and I5, in particular the sub-formulas I4a and I5a are preferred:

L ^b , L ^c = each independently of one another H or F.

o = 2, 3, 4 oder 5,
L^b = H oder F.Further preferred sub-formulas of the formulas I1, I4a, I5a and I10 are the formulas I1a, I4a1, I5a1 and I10a:

o = 2, 3, 4 or 5,
^Lb = H or F.

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), namely under Reaction conditions which are known and suitable for the said reactions.

One can make use of known per se, not mentioned here variants.

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

Schema 2: Darstellung von Br-W

Schema 3: Darstellung von Br-W

Schema 4:

The compounds of the invention may, for. For example, according to the following Reaction Schemes 1 to 8: Scheme 1: Representation of Br-W

Scheme 2: Representation of Br-W

Scheme 3: Representation of Br-W

Scheme 4:

The coupling of the compounds Br-W prepared analogously to Schemes 1 to 4 to the mesogenic basic body R ¹ - (A ¹ -Z ¹ ) _n -A ² -Z ² - can be carried out by literature methods.

The linkage of a non-aromatic ring with an aromatic nucleus or the linkage of two aromatic nuclei can be carried out, for example, as shown in Scheme 4.

The preparation of compounds of the formula I in which Z ^{2 is} a single bond and the radical A ^{2 is} a 1,3-dioxane-2,5-diyl radical can be carried out, for example, by acetalization of a diol with an aldehyde, for. B. in the presence of an acid such as p-toluenesulfonic acid in an inert solvent such as. As n-pentane, cyclohexane or toluene. The representation of the aldehydes OHC-W from the aryl bromides Br-W can, for. Example, be achieved by converting the aryl bromides with magnesium in the corresponding Grignard compounds, these reacted with triethyl orthoformate and the reaction product hydrolyzed (Dornfeld CA, GH Coleman, Org. Synth. III, 701 (1955)).

The aromatic aldehydes OHC-W can be z. B. also obtained from the corresponding nitriles by these reacted, for example, with hydrogen chloride in the presence of anhydrous stannous chloride and then hydrolyzed (Stephen reduction).

The nitriles NC-W can z. B. can be obtained by adding the corresponding aryl bromides, for example with cyanides such as. Friedman, H. Shechter, J. Org. Chem., 26, 2522 (1961); MS Newman, H. Boden, J. Org. Chem. 26, 2525 (1961); Mowry, Chem. Rev. 42, 189 (1948)).

The preparation of the compounds of the formula I in which Z ^{2 is} -O-CO- or -CO-O- can be carried out, for example, by esterification reactions from the carboxylic acids HOOC-W or from the phenols HO-W (or from their reactive derivatives) , For the construction of esters in which Z ^{2 is} -O-CO-, the nitriles NC-W z. B. are converted into the corresponding carboxylic acids, for. B. by heating in the presence of mineral acids. For the construction of esters in which Z ^{2 is} -CO-O-, the aryl bromides Br-W z. B. in phenols HO-W convert. For this purpose, for example, the aryl bromides can first be reacted with diborane and lithium in THF and then oxidized with alkaline H ₂ O ₂ (GM Pickles, FG Thorpe, J. Organomet Chem 76, C23 (1974)).

Schema 6:

Schema 8:

Starting from the phenols HO-W can be obtained by etherification, for example, compounds of formula I in which Z ^{2 is} -CH ₂ O-. Ethers of the formula I in which Z ^{2 is} -OCH ₂ - can be obtained, for example, by etherification of the compounds HOCH ₂ -W (or their reactive derivatives). The corresponding alcohols can be z. B. obtained by reduction of aldehydes OHC-W. Scheme 5:

Scheme 6:

Scheme 8:

The ring closure shown in Schemes 1 and 6 to the substituted in the 5-position 3H-benzofuran-2-ones can, for. B. analogous to the methods described in A. Closse, W. Haeflinger, D. Hauser, J. Med. Chem. 24 (1981) 1465-1471.

These compounds can be converted to the corresponding 2,2-difluoro-2,3-dihydrobenzofurans by reaction with suitable fluorinating agents, such as SF ₄ in methylene chloride. By dehydrofluorination with suitable bases, such as. B. lithium diisopropylamide in THF 5-substituted 2-fluorobenzofurans are obtained.

However, the 3H-benzofuran-2-ones can also be converted to the 2-difluoromethylene-2,3-dihydrobenzofurans. For this purpose, for example, the reaction with dibromodifluoromethane in the presence of zinc and hexamethyltriaminophosphine in THF is suitable (J.S. Houlton, W.B. Motherwell, B.C. Ross, M.J. Tozer, D.J. Williams, A.M. Z. Slawin, Tetrahedron 49 (1993) 8087-8106). The reduction of these compounds, for example the catalytic hydrogenation with noble metals such as Pd, yields the corresponding 2-difluoromethyl-2,3-dihydrobenzofurans.

The ring closure shown in Schemes 2 and 7 to the substituted in the 5-position benzofuran-3-ones may, for. By analogy with that described in D.M. X. Donnelly, J.-P. Finet, J.M. Kielty, Tetrahedron Lett. 32 (1991) 2835-2836.

By suitable reduction of these compounds, for. B. with NaBH ₄ in methanol, and subsequent dehydration, for example acid catalysed with p-toluenesulfonic acid in toluene, the corresponding benzofurans are synthesized.

These substituted in 5-position benzofurans can be substituted electrophilically analogous to Schemes 3 and 8, wherein the corresponding 2,5-disubstituted benzofurans can be obtained. The electrophilic substitution takes place in such a way that the benzofurans substituted in the 5-position are first deprotonated with a suitable base, for example butyllithium in n-hexane or lithium diisopropylamide in solvents such as tetrahydrofuran or dimethylformamide, and then reacted with a suitable electrophile. In this way, the benzofurans can be halogenated, for example, in the 2-position, alkylated or cyanated. Suitable electrophilic reagents are, for. For example, selectfluor for fluorination, p-toluenesulfonyl cyanide for cyanations or 5-Trifluoromethyldibenzoselenopheniumtrifluoromethansulfonat to introduce a trifluoromethyl group.

The benzofuran-3-ones substituted in the 5-position can also be converted into the corresponding 2,3-difluorobenzofurans analogously to Schemes 2 and 7. For this purpose, the benzofuran-3-ones are first by electrophilic substitution, z. B. by deprotonation with LDA in THF and fluorination with N-fluorobenzenesulfonimide, converted into the corresponding 2-fluorobenzofuran-3-one.

These can be converted to the desired products after reaction with suitable fluorinating agents such as diethylaminosulfur trifluoride and dehydrofluorination of the fluorination products. For dehydrofluorination suitable bases may be used, such as. For example, lithium diisopropylamide in THF. The syntheses of the 2- and 3-fluorobenzofurans additionally shown in Schemes 2 and 7 are carried out by reactions described above.

Schema 10:

Schema 11:

Schema 12:

Schema 13:

Schema 14:

Preferred compounds of the formula I are prepared as follows:

Scheme 10:

Scheme 11:

Scheme 12:

Scheme 13:

Scheme 14:

Esters of the formula I can also be obtained by esterification of corresponding carboxylic acids (or their reactive derivatives) with alcohols or phenols (or their reactive derivatives) or by the DCC method (DCC = dicyclohexylcarbodiimide).

The corresponding carboxylic acids and alcohols or phenols are known or can be prepared analogously to known processes.

Particularly suitable as reactive derivatives of said carboxylic acids are the acid halides, especially the chlorides and bromides, and also the anhydrides, azides or esters, in particular alkyl esters having 1-4 C atoms in the alkyl group.

Suitable reactive derivatives of said alcohols or phenols are, in particular, the corresponding metal alcoholates or phenolates, preferably an alkali metal such as Na or K.

The esterification is advantageously carried out in the presence of an inert solvent. Especially suitable are ethers such as diethyl ether, di-n-butyl ether, THF, dioxane or anisole, ketones such as acetone, butanone or cyclohexanone, amides such as DMF or phosphoric acid hexamethyltriamide, hydrocarbons such as benzene, toluene or xylene, halogenated hydrocarbons such as carbon tetrachloride or tetrachlorethylene and sulfoxides such as Dimethyl sulfoxide or sulfolane. Water-immiscible solvents can also be advantageously used to azeotropically distill off the water formed in the esterification. Occasionally, an excess of an organic base, for. As pyridine, quinoline or triethylamine, be used as a solvent for the esterification. The esterification can also in the absence of a solvent, for. B. by simply heating the components in the presence of sodium acetate, performed. The reaction temperature is usually between -50 ° and + 250 °, preferably between -20 ° and + 80 °. At these temperatures, the esterification reactions are usually completed after 15 minutes to 48 hours.

In particular, the reaction conditions for the esterification depend largely on the nature of the starting materials used. Thus, a free carboxylic acid is reacted with a free alcohol or phenol usually in the presence of a strong acid, for example a mineral acid such as hydrochloric acid or sulfuric acid. A preferred reaction method is the reaction of an acid anhydride or in particular an acid chloride with an alcohol, preferably in a basic medium, using as bases in particular alkali metal hydroxides such as sodium or potassium hydroxide, alkali metal carbonates or bicarbonates such as sodium carbonate, sodium bicarbonate, potassium carbonate or potassium bicarbonate, alkali metal acetates such as sodium or potassium acetate, alkaline earth metal hydroxides such as calcium hydroxide or organic bases such as triethylamine, pyridine, lutidine, collidine or quinoline are of importance. Another preferred embodiment of the esterification is that the alcohol or phenol is first converted into the sodium or potassium alcoholate or phenolate, z. B. by treatment with ethanolic sodium or potassium hydroxide solution, this isolated and reacted with an acid anhydride or in particular acid chloride.

Nitriles can be obtained by exchanging halogens with copper cyanide or alkali cyanide.

In a further process for the preparation of the compounds of the formula I in which Z ¹ or Z ^{2 is} -CH = CH-, an aryl halide is reacted with an olefin in the presence of a tertiary amine and a palladium catalyst (see RF Heck, Acc Res. 12 (1979) 146). Suitable aryl halides are, for example, chlorides, bromides and iodides, in particular bromides and iodides. The required for the success of the coupling reaction tertiary amines such. As triethylamine, are also suitable as a solvent. As palladium catalysts are, for example, its salts, in particular Pd (II) acetate, with organic phosphorus (III) compounds such. B. triarylphosphines suitable. It can be in the presence or absence of an inert solvent at temperatures between about 0 ° C and 150 ° C, preferably between 20 ° C and 100 ° C work. As a solvent come z. As nitriles such as acetonitriles or hydrocarbons such as benzene or toluene into consideration. The aryl halides and olefins used as starting materials are widely available commercially or can be prepared by literature methods, for example by halogenation of corresponding parent compounds or by elimination reactions of corresponding alcohols or halides.

In this way, for example stilbene derivatives can be produced. The stilbenes can be further prepared by reacting a 4-substituted benzaldehyde with a corresponding Wittig phoshorylide. However, it is also possible to prepare tolans of the formula I by using monosubstituted acetylene instead of the olefin (Synthesis 627 (1980) or Tetrahedron Lett. 27, 1171 (1986)).

Furthermore, aryl halides can be reacted with aryl tin compounds for the coupling of aromatics. These reactions are preferred with the addition of a catalyst such as. A palladium (0) complex in inert solvents such as hydrocarbons at high temperatures, e.g. B. in boiling xylene, carried out under inert gas.

Couplings of alkynyl compounds with aryl halides can be carried out analogously to the method described by A.O. King, E. Negishi, F.J. Villani, and A. Silveira in J. Org. Chem., 43, 358 (1978).

Tolanes of the formula I in which Z ¹ or Z ^{2 is} -C≡C- can also be prepared via the Fritsch-Buttenberg-Wiechell rearrangement (Ann., 279, 319, 1984), in which 1,1-diaryl-2 -halogenoethylenes are rearranged to diarylacetylenes in the presence of strong bases.

Tolans of formula I can also be prepared by brominating the appropriate stilbene and then subjecting to dehydrohalogenation. In this case, one can use known per se, not mentioned here variants of this implementation.

Ethers of the formula I are obtainable by etherification of corresponding hydroxy compounds, preferably corresponding phenols, wherein the hydroxy compound is first expediently converted into a corresponding metal derivative, eg. B. by treatment with NaH, NaNH ₂ , NaOH, KOH, Na ₂ CO ₃ or K ₂ CO ₃ , is converted into the corresponding alkali metal or alkali metal phenolate. This can then be reacted with the corresponding alkyl halide, sulfonate or dialkyl sulfate, suitably in an inert solvent such as. As acetone, 1,2-dimethoxyethane, DMF or dimethyl sulfoxide or with an excess of aqueous or aqueous-alcoholic NaOH or KOH at temperatures between about 20 ° C and 100 ° C.

For the preparation of the laterally substituted fluoro or chloro compounds of the formula I, corresponding aniline derivatives with sodium nitrite and either with tetrafluoroboric acid (for introducing an F atom) or with copper (I) chloride (for introducing a Cl atom) to the Diazonium salts are reacted, which are then thermally decomposed at temperatures of 100 ° -140 °.

The linking of an aromatic nucleus with a non-aromatic nucleus or two non-aromatic nuclei is preferably obtained by condensation of a lithium or organomagnesium compound with a ketone, if between the nuclei an aliphatic group Z ¹ and / or Z ² should be.

The organometallic compounds are prepared, for example, by metal-halogen exchange (for example according to Org. React. 6, 339-366 (1951)) between the corresponding halogen compound and an organolithium compound such as preferably n-butyllithium, tert-butyllithium or lithium -Naphthalenid or by sales of magnesium turnings ago.

The linking of two aromatic rings or an aliphatic group Z ¹ and / or Z ² with an aromatic ring is preferably carried out by Friedel-Crafts alkylation or acylation by reacting the corresponding aromatic compounds under Lewis acid catalysis. Suitable Lewis acids are, for. As SnCl ₄ , ZnCl ₂ or especially AlCl ₃ and TiCl ₄ .

Furthermore, the linkage of two aromatic rings by the Ullmann reaction (eg Synthesis 1974, 9) between aryl iodides with copper iodide, but preferably between an aryl-copper compound and an aryl iodide, or by the Gomberg-Bachmann reaction between an aryl diazonium salt and the corresponding aromatic compound (e.g., Org. React. 2, 224 (1944)). The representation of the tolans of the formula I (Z ¹ and / or Z ² = -C≡C-) takes place z. By reacting the corresponding aryl halides with an acetylide in a basic solvent under transition metal catalysis; Palladium catalysts may preferably be used here, in particular a mixture of bis (triphenylphosphine) palladium (II) chloride and copper iodide in piperidine as solvent.

Moreover, the compounds of the formula I can be prepared by reducing a compound which otherwise corresponds to the formula I but contains one or more reducible groups and / or C-C multiple bonds instead of H atoms.

As reducible groups are preferably carbonyl groups, in particular keto groups, also z. B. free or esterified hydroxy groups or aromatically bound halogen atoms. Preferred starting materials for the reduction are compounds corresponding to the formula I, but instead of a cyclohexane ring, a cyclohexene ring or cyclohexanone ring and / or in place of a -CH ₂ CH ₂ group a -CH = CH group and / or in place of a -CH ₂ group a -CO-group and / or in place of an H atom a free or a functional modified (eg in the form of its p-toluenesulfonate) OH group included.

The reduction can z. Example, by catalytic hydrogenation at temperatures between about 0 ° and about 200 ° and pressures between about 1 and 200 bar in an inert solvent, for. An alcohol such as methanol, ethanol or isopropanol, an ether such as tetrahydrofuran (THF) or dioxane, an ester such as ethyl acetate, a carboxylic acid such as acetic acid or a hydrocarbon such as cyclohexane. Suitable catalysts are suitably noble metals such as Pt or Pd, which can be used in the form of oxides (eg PtO ₂ , PdO), on a support (eg Pd on carbon, calcium carbonate or strontium carbonate) or in finely divided form ,

Ketones can also be prepared by the methods of Clemmensen (with zinc, amalgamated zinc or tin and hydrochloric acid, expediently in aqueous-alcoholic solution or in heterogeneous phase with water / toluene at temperatures between about 80 and 120 °) or Wolff-Kishner (with hydrazine, conveniently in the presence of alkali such as KOH or NaOH in a high boiling solvent such as diethylene glycol or triethylene glycol at temperatures between about 100 and 200 °) to the corresponding compounds of formula I containing alkyl groups and / or -CH ₂ CH ₂ bridges ,

Furthermore, reductions with complex hydrides are possible. For example, arylsulfonyloxy with LiAlH ₄ can be removed reductively, in particular p-toluenesulfonyloxymethyl be reduced to methyl groups, advantageously in an inert solvent such as diethyl ether or THF at temperatures between about 0 and 100 °. Double bonds can be hydrogenated with NaBH ₄ or tributyltin hydride in methanol.

The starting materials are either known or can be prepared in analogy to known compounds.

The liquid-crystalline media according to the invention preferably comprise, in addition to one or more compounds according to the invention as further constituents 2 to 40, in particular 4 to 30 components. With very particular preference these media contain, in addition to one or more compounds according to the invention, 7 to 25 components. 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, phenyl or cyclohexyl benzoates, cyclohexanecarboxylic acid phenyl or cyclohexyl esters, phenyl or cyclohexyl esters of Cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexyl phenyl esters of benzoic acid, of cyclohexanecarboxylic acid or of cyclohexanecyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-biscyclohexylbenzenes, 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-Cyc lohexyl-2-biphenylylethanes, 1-phenyl-2-cyclohexyl-phenylethanes, optionally halogenated stilbenes, benzylphenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be fluorinated.

The most important compounds which may be used as further constituents of media according to the invention can be characterized by the formulas 1, 2, 3, 4 and 5: R'-LE-R '' 1 R'-L-COO-E-R "2 R'-L-OOC-E-R "3 R'-L-CH ₂ CH ₂ -E-R "4 R'-LC≡CE-R "5

In formulas 1, 2, 3, 4 and 5, L and E, which may be the same or different, each independently represents a bivalent radical selected from the group consisting of -Phe-, -Cyc-, -Phe-Phe-, -Phe- Cyc, -Cyc-Cyc, -Pyr-, -Dio, -G-Phe- and -G-Cyc- and their mirror images formed group, wherein Phe is unsubstituted or fluorine-substituted 1,4-phenylene, cyc trans-1,4-cyclohexylene or 1,4-cyclohexenylene, pyr pyrimidine-2,5-diyl or pyridine-2,5-diyl, dio-1,3-dioxane-2, 5-diyl and G is 2- (trans-1,4-cyclohexyl) -ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl or 1,3-dioxane-2,5-dryl.

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 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 R "in a smaller subgroup of the compounds of formulas 1, 2, 3, 4 and 5 are each independently alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or alkanoyloxy of up to 8 carbon atoms. In the following, this smaller subgroup will be called Group A and the compounds will be referred to as Partial Formulas 1a, 2a, 3a, 4a and 5a. 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 a smaller subgroup of the compounds of formulas 1, 2, 3, 4 and 5, other than group B, R '' is -F, -Cl, -NCS or - (O) ₁ CH ₃ - _{(k + 1)} F _k Cl _l , where i is 0 or 1 and k + 1 is 1, 2 or 3. The compounds in which R "has this meaning are designated by the subformulae 1b, 2b, 3b, 4b and 5b. Particular preference is given to those compounds of the subformulae 1b, 2b, 3b, 4b and 5b in which R "has the meaning -F, -Cl, -NCS, -CF ₃ , -OCHF ₂ or -OCF ₃ .

In the compounds of sub-formulas 1b, 2b, 3b, 4b and 5b, R 'has the meaning given for the compounds of sub-formulas 1a-5a and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl.

In another smaller subgroup of the compounds of formulas 1, 2, 3, 4 and 5, R "is -CN; this subgroup is referred to below as group C and the compounds of this subgroup are described respectively with sub-formulas 1c, 2c, 3c, 4c and 5c. In the compounds of sub-formulas 1c, 2c, 3c, 4c and 5c, R 'has the meaning given in the compounds of sub-formulas 1a-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 the group A and / or group B and / or group C. The mass fractions of the compounds from these groups on the media according to the invention are preferred Group A: 0 to 90%, preferably 20 to 90%, in particular 30 to 90% Group B: 0 to 80%, preferably 10 to 80%, especially 10 to 65% Group C: 0 to 80%, preferably 5 to 80%, especially 5 to 50% wherein the sum of the mass fractions of the compounds of the groups A and / or B and / or C contained in the respective inventive media is preferably 5% to 90% and in particular 10% to 90%.

The media according to the invention preferably contain 1 to 40%, in particular preferably 5 to 30%, of compounds according to the invention. Also preferred are media containing more than 40%, in particular 45 to 90%, of compounds according to the invention. The media preferably contain three, four or five compounds according to the invention.

The preparation of the media according to the invention is carried out in a conventional manner. In general, the components are dissolved in each other, useful at elevated temperature. By suitable additives, the liquid-crystalline phases according to the invention can be modified so that they are known in all hitherto have become used types of liquid crystal display elements. Such additives 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 added for the preparation of colored guest-host systems or substances for changing the dielectric anisotropy, the viscosity and / or the orientation of the nematic phases.

The following examples are intended to illustrate the invention without limiting it. Above and below, percentages are by weight. All temperatures are in degrees Celsius. Mp means melting point, Kp = clearing point. Furthermore, K = crystalline state, N = nematic phase, S = smectic phase and I = isotropic phase. The data between these symbols represent the transition temperatures. Δn means optical anisotropy (589 nm, 20 ° C) and the viscosity (mm ² / sec) was determined at 20 ° C.

"Usual workup" means: water is added if necessary, if necessary, depending on the constitution of the final product to pH values between 2 and 10, extracted with dichloromethane, diethyl ether, methyl tert-butyl ether or toluene, separates, The organic phase is dried, evaporated and the product purified by distillation under reduced pressure or crystallization and / or chromatography.

AcOH

Eisessig (Essigsäure)

Ac₂O

Essigsäureanhydrid

BuLi

n-Butyllithium

DAST

Diethylamino-schwefeltrifluorid

DCC

Dicyclohexylcarbodiimid

DMF

Dimethylformamid

LDA

Lithiumdiisopropylamid

MeOH

Methanol

NaOAc

Natriumacetat

NFSi

N-Fluorbenzolsulfonimid

PdCl₂ (dppf)

(Diphenylphosphinoferrocen)palladiumdichlorid

Pd-C

Palladium auf Aktivkohle

PPh₃

Triphenylphosphin

R(NMe₂)₃

Hexamethyltriaminophosphin

Selectfluor

N-Fluor-N-Chlormethyltriethylendiamin-bis(tetrafluorborat)

THF

Tetrahydrofuran

TsCN

p-Toluolsulfonylcyanid

TsOH

p-Toluolsulfonsäure

Beispiel 1

The following abbreviations are used:

AcOH

Glacial acetic acid

Ac ₂ O

acetic anhydride

BuLi

n-butyllithium

DAST

Diethylaminosulfur trifluoride

DCC

dicyclohexylcarbodiimide

DMF

dimethylformamide

LDA

lithium

MeOH

methanol

NaOAc

sodium

NFSi

N-fluorobenzenesulphonimide

PdCl ₂ (dppf)

(Diphenylphosphinoferrocene) palladium dichloride

Pd-C

Palladium on activated carbon

PPh ₃

triphenylphosphine

R (NMe ₂ ) ₃

Hexamethyltriaminophosphin

Select fluorine

N-fluoro-N-Chlormethyltriethylendiamin-bis (tetrafluoroborate)

THF

tetrahydrofuran

TsCN

p-toluenesulfonyl

TsOH

p-toluenesulfonic acid

example 1

A mixture of 13.3 mmol trans-4-pentylcyclohexane-carboxylic acid, 13.3 mmol 1.16 mmol DCC and 150 ml THF is stirred for 12 h at room temperature. Subsequently, a further 11 mmol DCC are added and worked up after four hours of stirring at 45 ° C as usual. 2 is obtained; K 139 l. Example 2 Step 1

A solution of 1.5 mol NaOH in 150 ml H ₂ O is added with stirring to a mixture of 760 mmol 3, 860 mmol bromoacetic acid and 600 ml H ₂ O. The mixture is then heated with gentle stirring for 12 h to a weak boil, then 148 ml of aqueous hydrochloric acid (37 wt .-%) was added and the resulting suspension subjected to a steam distillation. After usual work-up you get 4th step 2

A mixture of 530 mmol 4, 2.32 mol of sodium acetate, 490 ml of acetic anhydride and 490 ml of glacial acetic acid is heated with stirring for 48 h to reflux. Subsequently, the hot solution is added to 2.5 l of ice water and worked up as usual. You get 5th step 3

At 2 ° C., 48 mmol of lithium granules are added to 24 mmol of 6.12 mmol of ZnBr ₂ and 36 ml of a toluene / THF mixture (toluene: THF 4: 1). The mixture is sonicated at 5 ° C for 4 h, then 24 mmol 5 and 0.2 g of PdCl ₂ (dppf) are added and stirred for 48 h at room temperature. After addition of 25 ml of a saturated NH ₄ Cl solution and stirring at room temperature for 1 hour, the mixture is worked up as usual. One obtains 7; K 80 S _B 110 N 158 I; Δε = +0.83; Δn = + 0.108. Example 3

To a mixture of 50 mmol 5 and 50 mmol 8 in 50 ml THF and 75 mmol NaHCO ₃ in 25 ml H ₂ O is added a suspension of 0.2 g PdCl ₂ , 0.6 g PPh ₃ and 0.05 g NaBH ₄ in 25 ml of THF previously stirred for 0.5 h under nitrogen. It is then refluxed for 12 h and worked up as usual. 9 is obtained; K 187 N 189.2 I. Example 4

To a solution of 20 mmol 10 in 25 ml of THF under inert gas and stirring at -78 ° C, first a solution of 20 mmol BuLi in n-hexane (1.8 molar solution) was added dropwise and then a suspension of 22 mmol Selectfluor in 35 ml acetonitrile added. The mixture is stirred for 2 h at -78 ° C, then allowed to warm slowly to room temperature and stirred for a further 12 h. After usual work-up gives 11.

Analogously to Examples 1 to 4 are prepared: R ¹ - (A ¹ -Z ¹ ) _n -A ² -Z ² -W

Claims (11)

Benzofuran derivatives of the formula I R ¹ - (A ¹ -Z ¹ ) _n -A ² -Z ² -W

L ¹ , L ² and L ^{3 are} each independently H or F, Y CF ₂ , C = O, C = CF ₂ or CH-CHF ₂ , X ¹ and X ^{2 are} each independently H, F, CN, an unsubstituted or a straight-chain or branched alkyl or alkoxy radical having 1 to 12 C atoms substituted by one or more fluorine atoms or a straight-chain or branched alkenyl or alkenyloxy radical having 2 to 12 C atoms which is unsubstituted or substituted by one or more fluorine atoms, R ¹ H , an unsubstituted, straight-chain or branched alkyl radical having 1 to 12 C atoms or alkenyl radical having 2 to 12 C atoms which is monosubstituted by CN or CF ₃ or at least monosubstituted by halogen, where one or more CH ₂ - Each independently of one another by -O-, -S-,

-CO-, -CO-O-, -O-CO- or -O-CO-O- can be replaced so that heteroatoms are not directly linked, A ¹ and A ^{2 are} each independently a) trans-1 , 4-cyclohexylene radical, in which also one or more non-adjacent CH ₂ groups can be replaced by -O- and / or -S-, b) 1,4-cyclohexenylene radical, c) 1,4-phenylene radical, in which also one or d) radical from the group consisting of 1,4-bicyclo (2,2,2) -octylene, piperidine-1,4-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2 , 6-diyl and 1,2,3,4-tetrahydronaphthalene-2,6-diyl, where the radicals a), b) and c) may be substituted by CN, Cl or F c, Z ¹ and Z ² are each independently -CO-O-, -O-CO-, -CH ₂ O-, -OCH ₂ -, -CH ₂ CH ₂ -, -CH = CH-, -C≡C- or a single bond and n is 0, 1 or 2, wherein (a) at least one of the radicals L ¹ to L ^{3 is} F, or (b) X ^{2 has} a meaning other than H, when X ^{1 is} an unsubstituted alkyl or alkoxy radical and Ve in which L ¹ and L ^{2 are} F, L ³ and X ^{2 are} H and X ^{1 is} H or unsubstituted alkyl. Tetrahydrofuranocyclohexane derivatives according to Claim 1, characterized in that R ^{1 is} a straight-chain unsubstituted alkyl radical or a straight-chain unsubstituted alkenyl radical. Benzofuran derivatives according to one of claims 1 or 2, characterized in that n is 0 and Z ^{2 is} -CO-O-, -O-CO- or a single bond, or that n 1 and Z ¹ and Z ^{2 are} a single bond. Benzofuran derivatives according to one of claims 1 to 3 of the formula I1

wherein R ¹ and W have the meanings indicated. Benzofuran derivatives according to one of claims 1 to 3 of the formula I4

wherein L ^a , L ^b , L ^c and L ^{d are} each independently H or F and R ¹ and W have the meanings indicated. Benzofuran derivatives according to one of claims 1 to 3 of the formula I5

wherein L ^a , L ^b , L ^c and L ^{d are} each independently H or F and R ¹ and W have the meanings indicated. Benzofuran derivatives according to one of claims 1 to 3 of the formula I10

wherein R ¹ and W have the meanings indicated. Benzofuran derivatives according to any one of claims 1 to 7 wherein W

means. Benzofuran derivatives according to any one of claims 1 to 7 wherein W

means. Use of compounds according to one of claims 1 to 9 as components of liquid-crystalline media. Liquid-crystalline medium having at least two liquid-crystalline components, characterized in that it contains at least one compound of claims 1 to 9.