DE102008027972B4 - naphthofuran derivatives - Google Patents

Abstract

Compounds of formula I:whereinm and n are each independently 0 or 1, where m + n is 0 or 1;L1 and L2 are each independently F;Y1-Y2>C=CH-;A1 and A2(a) are each independently 1 ,4-phenylene, or (b) 1,4-cyclohexylene;Z1 and Z2 are each independently a single bond; R1 and R2 are independently an unsubstituted alkanyl radical having 1 to 7 carbon atoms; and Ring B

Description

The present invention relates to naphthofuran derivatives, a process for their production, liquid-crystalline media containing these derivatives and electro-optical display elements containing these liquid-crystalline media. In particular, the invention relates to naphthofuran derivatives having negative dielectric anisotropy.

Liquid crystals have found a wide range of applications since the first commercially applicable liquid-crystalline compounds were found about 30 years ago. Known areas of application for conventional mixtures are, in particular, displays for clocks and pocket calculators, as well as large billboards such as those used in train stations, airports and sports arenas. Further areas of application are displays of portable and stationary computers, navigation systems and video applications. The last-mentioned applications in particular place high demands on switching times and the contrast of the images.

The spatial arrangement of the molecules in a liquid crystal means that many of its properties are directional. The anisotropies in the optical, dielectric and elasto-mechanical behavior are of particular importance for use in liquid-crystal displays. Depending on whether the molecules are oriented with their long axes perpendicular or parallel to the two plates of a capacitor, the capacitor has a different capacitance; the dielectric constant ε of the liquid-crystalline medium is therefore different for the two orientations. Substances whose dielectric constant is greater when the longitudinal axes of the molecules are perpendicular to the capacitor plates than when they are arranged parallel are referred to as dielectrically positive. In other words: Is the dielectric constant ε _|| parallel to the longitudinal axes of the molecules is greater than the dielectric constant ε _⊥ perpendicular to the longitudinal axes of the molecules, then the dielectric anisotropy is Δε = ε _|| - ε _⊥ greater than zero. Most liquid crystals used in conventional displays fall into this group.

Both the polarizability of the molecule and permanent dipole moments play a role in the dielectric anisotropy. When a voltage is applied to the display, the long axis of the molecules aligns 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. Small differences require higher switching voltages than large ones. A wide range of working voltages can be realized by incorporating suitable polar groups, such as nitrile groups or fluorine, into the liquid crystal molecules.

In the case of the liquid-crystalline molecules used in conventional liquid-crystal displays, the dipole moment oriented along the longitudinal axis of the molecule is greater than the dipole moment oriented perpendicularly to the longitudinal axis of the molecule. In the most common TN cells (derived from the English: "twisted nematic"), a liquid-crystalline layer only about 5 to 10 µm thick is arranged between two plane-parallel glass plates, each of which has an electrically conductive, transparent layer of tin oxide or indium tin oxide (ITO) is vapor-deposited as an electrode. Between these films and the liquid crystal layer there is also a transparent orientation layer, which usually consists of a plastic (e.g. polyimide). It serves to bring the longitudinal axes of the neighboring crystalline molecules in a preferred direction by means of surface forces, so that in the stress-free state they lie flat on the inside of the display surface with the same orientation or with the same small tilt angle. On the outside of the display, two polarizing foils are applied in a specific arrangement, which only allow linearly polarized light to enter and exit.

Very powerful displays have already been developed with liquid crystals in which the larger dipole moment is oriented parallel to the longitudinal axis of the molecule. Mixtures of 5 to 20 components are usually used in order to aim for a sufficiently wide temperature range of the mesophase as well as short switching times and low threshold voltages. However, difficulties are still caused by the strong viewing angle dependency of liquid crystal displays, such as those used for laptops. The best image quality can be achieved when the surface of the display is perpendicular to the direction of view of the viewer. If the display is tilted relative to the viewing direction, the image quality may deteriorate drastically. For greater convenience, efforts are being made to make the angle by which the display can be tilted from the direction of view of a viewer without any significant reduction in the imaging quality as large as possible. Recently, attempts have been made to use 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 to improve the viewing angle dependence molecule. The dielectric anisotropy Δε is negative in this case. In the field-free state, these molecules are oriented with their long axis perpendicular to the glass surface of the display. By applying an electrical field, they orient themselves more or less parallel to the glass surfaces. In this way, an improvement in the viewing angle dependency could be achieved. Such displays are referred to as VA-TFT displays (derived from the English: "vertically aligned").

The development in the field of liquid-crystalline materials is far from over. In order to improve the properties of liquid-crystalline display elements, it is desirable to develop new compounds that enable such displays to be optimized.

In the pamphlets WO 2005/021682 A1 and WO 2004/020375 A1 cyclopentanaphthalenes with differently composed ring systems are disclosed. These purely carbocyclic compounds do not have a furan ring within the tricyclic system. The preparation of the compounds cannot be transferred to other tricyclic systems with heteroatoms.

Other liquid crystal compounds whose molecular structures have a tricyclic fused ring system are described in the publications DE 2238628 A1 , DE 102004037387 A1 and DE 102005037925 A1 disclosed. They differ from the present disclosure by, among other things, the occurrence and the position of the O-heteroatom and/or the degree of saturation of the naphthyl system. The pamphlet US4111962A discloses naphtho[2,1-b]furans and their preparation for other purposes.

One object of the present invention is to provide compounds with 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. Regardless of the dielectric anisotropy corresponding to the type of display, compounds are desired which have a favorable combination of application parameters. Among these parameters to be optimized at the same time, a high clearing point, a low rotational viscosity, an optical anisotropy in the application interval, and the properties that serve to achieve mixtures with the desired liquid-crystalline phases over a wide temperature range should be mentioned in particular.

worin

m und n

jeweils unabhängig voneinander 0, 1, 2 oder 3 sind, bevorzugt 0, 1 oder 2, wobei m +n ≤ 4;

L1 und L2

jeweils unabhängig voneinander H, Halogen, CN, CF₃, CHF₂, CH₂F oder CH₃ bedeuten, bevorzugt H, F, CI, CN oder CF₃;

Y1-Y2

>C=CH- oder >CH-CH₂- bedeuten;

A1 und A2

jeweils unabhängig voneinander (a) 1 ,4-Phenylen, worin =CH- ein- oder zweimal durch =N- ersetzt sein kann und das unsubstituiert oder ein- bis viermal unabhängig voneinander mit -CN, -F, -Cl, -Br, -I, unsubstituiertem oder mit Fluor und/oder Chlor ein- oder mehrfach substituiertem C₁-C₆-Alkanyl, unsubstituiertem oder mit Fluor und/oder Chlor ein- oder mehrfach substituiertem C₁-C₆-Alkoxy substituiert sein kann, (b) 1,4-Cyclohexylen, 1,4-Cyclohexenylen oder 1,4-Cyclohexadienylen, worin -CH₂- ein- oder zweimal unabhängig voneinander durch -O- oder -S- so ersetzt sein kann, dass Heteroatome nicht direkt verknüpft sind, und die unsubstituiert oder ein- oder mehrfach durch -F und/oder -CI substituiert sein können, oder (c) Bicyclo[1.1.1]pentan-1,3-diyl, Bicyclo[2.2.2]octan-1,4-diyl oder Spiro[3.3]heptan-2,6-diyl, bedeutet;

Z1 und Z2

jeweils unabhängig voneinander eine Einfachbindung, -CF₂O-, -OCF₂-, -CH₂CH₂-, -CF₂CF₂-, -CF₂CH₂-, -CH₂CF₂-, -(CO)O-, -O(CO)-, -CH₂O-, -OCH₂-, -CF=CH-, -CH=CF-, -CF=CF-, -CH=CH-, -C≡C- oder eine Kombination aus zwei dieser Gruppen, wobei O-Atome nicht direkt verknüpft sind, bedeuten;

R1 und R2

unabhängig voneinander, Wasserstoff, einen unsubstituierten, einen einfach mit -CN- oder einen einfach oder mehrfach mit -F, -Cl, und/oder -Br substituierten Alkanyl-, Alkoxy-, Alkenyl- oder Alkinylrest mit 1 bis 15 bzw. 2 bis 15 C-Atomen, wobei in diesen Resten auch eine oder mehrere CH₂-Gruppen jeweils unabhängig voneinander durch -O-, -S-, -SO₂-, -CO-, -(CO)O-, -O(CO)- oder -O(CO)O- so ersetzt sein können, dass Heteroatome nicht direkt verknüpft sind, -F, -Cl, -Br, -CN, -NCS oder -SF₅ bedeuten; und

Ring B

wobei

A1 und A2 bzw. Z1 und Z2

jeweils die gleiche oder unterschiedliche Bedeutungen haben können, wenn m oder n größer als 1 sind, und,

wobei für den Fall, dass zugleich n = 0, m = 0 und L¹, L² ungleich F sind, R¹ und R² dann nicht gleichzeitig H bedeuten.This object is achieved according to the invention by compounds of the general formula I [partly not according to the claims]

wherein

m and n

are each independently 0, 1, 2 or 3, preferably 0, 1 or 2, where m +n ≤ 4;

L1 and L2

are each independently H, halogen, CN, CF ₃ , CHF ₂ , CH ₂ F or CH ₃ , preferably H, F, Cl, CN or CF ₃ ;

Y1-Y2

>C=CH- or >CH-CH ₂ -;

A1 and A2

each independently of one another (a) 1,4-phenylene, in which =CH- can be replaced once or twice by =N- and which is unsubstituted or one to four times independently of one another by -CN, -F, -Cl, -Br, -I, C ₁ -C ₆ -alkanyl which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, C ₁ -C ₆ -alkoxy which is unsubstituted or mono- or polysubstituted by fluorine and/or chlorine, (b ) 1,4-cyclohexylene, 1,4-cyclohexenylene or 1,4-cyclohexadienylene, in which -CH ₂ - can be replaced once or twice independently by -O- or -S- in such a way that heteroatoms are not directly linked, and which may be unsubstituted or substituted one or more times by -F and/or -CI, or (c) bicyclo[1.1.1]pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4- diyl or spiro[3.3]heptane-2,6-diyl;

Z1 and Z2

each independently a single bond, -CF ₂ O-, -OCF ₂ -, -CH ₂ CH ₂ -, -CF ₂ CF ₂ -, -CF ₂ CH ₂ -, -CH ₂ CF ₂ -, -(CO)O -, -O(CO)-, -CH ₂ O-, -OCH ₂ -, -CF=CH-, -CH=CF-, -CF=CF-, -CH=CH-, -C≡C- or a combination of two of these groups, where O atoms are not directly linked;

R1 and R2

independently of one another, hydrogen, an alkanyl, alkoxy, alkenyl or alkynyl radical with 1 to 15 or 2 bis which is unsubstituted once by -CN- or substituted once or several times by -F, -Cl and/or -Br 15 C-atoms, one or more CH ₂ groups in these radicals being independently replaced by -O-, -S-, -SO ₂ -, -CO-, -(CO)O-, -O(CO) - or -O(CO)O- can be replaced in such a way that heteroatoms are not directly linked, -F, -Cl, -Br, -CN, -NCS or -SF ₅ mean; and

Ring B

whereby

A1 and A2 or Z1 and Z2

each may have the same or different meanings when m or n is greater than 1, and,

where n=0, m=0 and L ¹ , L ² are not equal to F at the same time, R ¹ and R ² are then not simultaneously H.

The compounds predominantly have a negative Δε and are therefore particularly suitable for use in VA-TFT displays. The compounds according to the invention preferably have a Δε<-2 and particularly preferably a Δε<-4. They show very good compatibility with the customary substances used in liquid-crystal mixtures for displays. The compounds according to the invention have good solubility in liquid-crystalline mixtures, in particular in highly polar mixtures.

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 the use of the compounds in liquid-crystalline media. The compounds or liquid-crystalline media which contain these compounds have, in particular, a sufficiently wide nematic phase and good low-temperature and long-term stability, as well as sufficiently high clearing points. The rotational viscosities of the compounds are advantageously small, especially for m+n = 0.

Among the meanings for the substituents L ¹ and L ^2, preference is given to H, F and CI, in particular H and F. It is also preferred that one or two of the radicals L ¹ and L ² are CI or F, in particular fluorine. L ¹ is preferably fluorine. L ¹ and L ² are particularly preferably F.

In the event that m = 0, R ¹ is preferably not H.

If the radical R ² is a fluorine atom or fluorinated alkyl, in particular if n is 0 at the same time, then the formula I also includes compounds which can have an overall positive dielectric anisotropy. Such compounds are then suitable for dielectrically positive liquid crystal mixtures in displays such. B. of the type TN-TFT or IPS ('in-plane-switching') can be used. The requirements for the other physical parameters, such as viscosity, are largely congruent across most applications. The compounds mentioned are therefore equally suitable for these purposes because they have favorable values for the parameters such as rotational viscosity, Δn, etc. and are suitable for building up liquid-crystalline mixtures.

A ¹ and A ² are preferably and independently an optionally substituted 1,4-phenylene, an optionally substituted 1,4-cyclohexylene in which -CH ₂ - may be replaced once or twice by -O-, or an optionally substituted 1 ,4-cyclohexenylene. The substitution of the rings from groups (a) and (b), if present, is a group F or CI, preferably F. When n or m are 2, the rings A ¹ or A ² can have the same or different meanings. The same applies to Z ¹ and Z ² .

oder

besonders

oder

A ¹ and A ² are particularly preferably, independently of one another, to the extent that they are present

or

particularly

or

A ¹ and A ² are very particularly preferably 1,4-cyclohexylene and/or 1,4-phenylene optionally substituted with fluorine.

Preferably, Z ¹ and Z ² are independently a single bond, -CH ₂ O-, -OCH ₂ -, -CF ₂ O-, -OCF ₂ -, -CF ₂ CF ₂ -, -CH=CH-, -CF= CH-, -CH=CF- or -CF=CF-, particularly preferably independently a single bond, -CF ₂ O-, -OCF ₂ -, -CF ₂ CF ₂ -, -CH=CH-, -CF=CH -, -CH=CF-, -CH ₂ O-, -OCH ₂ - or -CF=CF-. Z ¹ and Z ² are very particularly preferably, independently of one another, a single bond, -CF ₂ O-, -OCF ₂ -, -CH ₂ O-, -OCH ₂ - or -CF=CF-, in particular a single bond.

oder

und ganz besonders bevorzugt eine der weiter unten oder in den Beispielen innerhalb von Formeln angeführten Formen.The ring B preferably has the form of one of the following formulas:

or

and very particularly preferably one of the forms given below or in the examples within formulas.

The group >Y ¹ -Y ² - preferably means >C=CH-.

The parameters m and n in the sum m+n preferably have a value of 0, 1, 2 or 3, particularly preferably 0, 1 or 2. Preferably one of the parameters m and n has the value 0 and the other a value such as defined above, preferably> 0. It is therefore particularly preferred that m=0 and n=0, 1 or 2 or n=0 and m=0, 1 or 2.

If R ¹ and R ² in formula I each independently represent an alkanyl radical and/or an alkoxy radical (alkyloxy radical) having 1 to 15 carbon atoms, these are straight-chain or branched. Each of these radicals is preferably straight-chain, has 1, 2, 3, 4, 5, 6 or 7 carbon atoms and is therefore preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.

R ¹ and R ² in formula I can each independently also be an oxaalkyl radical, ie an alkanyl radical in which at least one of the non-terminal CH ₂ groups of the alkanyl radical 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, R ¹ and R ² in formula I can also independently be thioalkanyl or sulfonalkanyl radicals, ie alkanyl radicals in which a CH ₂ group has been replaced by —S— or —SO ₂ —.

R ¹ and R ² in formula I can also each independently be an alkenyl radical having 2 to 15 carbon atoms, which is straight-chain or branched and has at least one CC double bond. It is preferably straight-chain and has 2 to 7 carbon atoms. It is therefore preferably vinyl, prop-1- or prop-2-enyl, but-1-, 2- or but-3-enyl, pent-1-, 2-, 3- or pent-4-enyl, hex- 1-, 2-, 3-, 4- or hex-5-enyl, hept-1-, 2-, 3-, 4-, 5- or hept-6-enyl. If the two carbon atoms of the CC double bond are substituted, the alkenyl radical can be present as the E and/or Z isomer (trans/cis). In general, the respective E isomers are preferred.

In the same way as in the case of an alkanyl radical, at least one of the CH ₂ groups in an alkenyl radical can also be replaced by oxygen, sulfur or --SO ₂ --. In the case of replacement by -O-, an alkenyloxy radical (with terminal oxygen) or an oxaalkenyl radical (with non-terminal oxygen) is then present.

R ¹ and R ² in formula I can, independently of one another, also be an alkynyl radical having 2 to 15 carbon atoms, which is straight-chain or branched and has at least one CC triple bond.

R ¹ and R ² in formula I can each independently be an alkanyl radical having 1 to 15 carbon atoms, in which one CH ₂ group is replaced by -O- and one by -CO-, these preferably being adjacent. Thus, this includes an acyloxy group -CO-O- or an oxycarbonyl group -O-CO-. This radical is preferably straight-chain and has 2 to 6 carbon atoms. The following of these radicals are preferred: acetyloxy, propionyloxy, butyryloxy, pentanoyloxy, hexanoyloxy, acetyloxymethyl, propionyloxymethyl, butyryloxymethyl, pentanoyloxymethyl, 2-acetyloxyethyl, 2-propionyloxyethyl, 2-butyryloxyethyl, 2-acetyloxypropyl, 3-propionyloxypropyl, 4- acetyloxybutyl, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycar bonyl, pentoxycarbonyl, methoxycarbonylmethyl, ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonylmethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(propoxycarbonyl)ethyl, 3-(methoxycarbonyl)propyl, 3-(ethoxycarbonyl)propyl or 4- (methoxycarbonyl)butyl. Furthermore, an alkanyl radical can also have an -O-CO-O- unit. It is also possible to replace a CH ₂ group with just a -CO group (carbonyl function).

R ¹ and R ² in formula I can each independently be an alkenyl radical having 2 to 15 carbon atoms, in which a CH ₂ group is preferably adjacent to an unsubstituted or substituted -C=C unit by -CO-, - CO-O-, -O-CO- or -O-CO-O-, where this radical can be straight-chain or branched. The radical is preferably straight-chain and has 4 to 13 carbon atoms. Particularly preferred are 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. Correspondingly, a CH ₂ group can also be replaced by -CO-, -CO-O-, -O-CO- or -O-CO-O- in an alkynyl radical in the vicinity of a substituted -C≡C unit.

R ¹ and R ² in formula I can each independently be a mono-CN-substituted alkanyl radical or alkoxy radical having 1 to 15 carbon atoms or an alkenyl radical or alkynyl radical having 2 to 15 carbon atoms, these preferably being straight-chain. Substitution by -CN is possible in any position.

R ¹ and R ² in formula I can each independently be an alkanyl radical in which two or more CH ₂ groups are replaced by -O- and/or -CO-O-, which can be straight-chain or branched. It is preferably unbranched and has 3 to 12 carbon atoms.

R ¹ and R ² in formula I can each independently be an alkanyl radical or alkoxy radical having 1 to 15 carbon atoms or alkenyl radical or alkynyl radical having 2 to 15 carbon atoms which is mono- or polysubstituted by F, CI and/or Br, these radicals are preferably straight-chain and halogen is preferably -F and/or -Cl. In the case of multiple substitution, halogen is preferably -F. The resulting groups also include perfluorinated groups such as -CF ₃ . In the case of monosubstitution, the fluorine or chlorine substituent can be in any position, but is preferably in the ω-position.

R ¹ and R ² in formula I can also each independently be -F, -Cl, -Br, -CN, -NCS or -SF ₅ . In this case, the dielectric anisotropy increases towards more positive values. These substituents should not be selected for particularly strong negative dielectric anisotropies. For high Δε, however, they are preferred, specifically -F, -Cl, or also -OCF ₃ .

R ¹ and R ² , independently of one another, in the general formula I are particularly preferably hydrogen or an alkanyl, alkoxy or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms, each of these radicals preferably being unsubstituted or mono- or polysubstituted by halogen .
R ¹ and R ² are very particularly preferably, independently of one another, hydrogen or an alkanyl radical, alkoxy radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms, each of these radicals preferably being unsubstituted.

If m=0, R ¹ is preferably an alkyl or alkoxy group, H or F, particularly preferably an alkyl group having 1-6 carbon atoms.

For the substituents ^R.sup.1 and ^R.sup.2 , the restriction mentioned at the outset applies for the case when m and n are 0 and ^L.sup.1 , ^L.sup.2 are not equal to F. It is also preferable for the more general case when m and n are 0 that R ¹ and R ² are preferably not H at the same time. In these cases, it is particularly preferred that both substituents R ¹ and R ² are not H.

In the context of the present invention, halogen means fluorine, chlorine, bromine and iodine, in particular fluorine or chlorine.

In the context of the present invention, the term "alkyl" - unless otherwise defined elsewhere in this specification or in the claims - means a straight-chain or branched aliphatic hydrocarbon radical with 1 to 15 (ie 1, 2, 3, 4, 5 , 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15) carbon atoms. This radical is unsubstituted or mono- or polysubstituted by fluorine, chlorine, Bromine, iodine, carboxy, nitro, -NH ₂ , -N(alkanyl) ₂ and/or cyano, it being possible for multiple substitution to take place with the same or with different substituents. If this alkyl radical is a saturated radical, it is also referred to as “alkanyl”. Furthermore, the term “alkyl” also includes unsubstituted hydrocarbon radicals or hydrocarbon radicals which are substituted one or more times, identically or differently, in particular by —F, —Cl, —Br, —I and/or —CN, in which one or more CH ₂ groups are substituted in this way by -O- (“alkoxy”, “oxaalkyl”), -S-(“thioalkyl”), -SO ₂ -, -CH=CH- (“alkenyl”), -C≡C- (“alkynyl”), - CO-O-, -O-CO- or -O-CO-O- can be replaced, that heteroatoms (O, S) in the chain are not linked directly to each other.

L ¹ and L ² are particularly preferably H or F. At least one substituent from L ^1/2 is preferably not hydrogen, preferably fluorine. Both substituents L ¹ and L ² are particularly preferably not hydrogen, preferably fluorine.

In a further embodiment, it is advantageous if the compounds of the formula I have at least one fluorine substituent in the L ¹ , L ² positions or on the B ring. This usually results in a higher dielectric constant ε _⊥ . Preferably two or more of the substituents are fluorine.

worin die Parameter R¹, R², L¹, L², Z¹, Z², Ring B, m und n die oben unter Formel I gegebene Bedeutung haben und
Ring A¹ und Ring A² wie A¹ und A² in Formel I definiert sind.Particular preference is given to compounds of the formula I according to the invention selected from the sub-formula IA

wherein the parameters R ¹ , R ² , L ¹ , L ² , Z ¹ , Z ² , ring B, m and n have the meaning given above under formula I and
Ring A ¹ and Ring A ² are as defined for A ¹ and A ² in formula I.

worin
R¹, R², L¹, L² die gleichen sowie die gleichen bevorzugten Bedeutungen, wie für Formel I oben definiert, besitzen.Preferred compounds of formula I or IA, for which m + n = 0, are represented by the following formula:

wherein
R ¹ , R ² , L ¹ , L ² have the same and the same preferred meanings as defined for formula I above.

worin
R¹, R², A¹, A², L¹, L², Z¹ und Z² die gleichen sowie die gleichen bevorzugten Bedeutungen, wie für Formel I oben definiert, besitzen.Preferred compounds of formula I or IA, for which applies: m + n = 1, are represented by the following formulas:

wherein
R ¹ , R ² , A ¹ , A ² , L ¹ , L ² , Z ¹ and Z ² have the same and the same preferred meanings as defined for formula I above.

worin
R¹, R², A¹, A², L¹, L², Z¹ und Z² die gleichen sowie die gleichen bevorzugten Bedeutungen, wie für Formel I oben definiert, besitzen.Preferred compounds of formula I or IA, for which applies: m + n = 2, are represented by the following formulas:

wherein
R ¹ , R ² , A ¹ , A ² , L ¹ , L ² , Z ¹ and Z ² have the same and the same preferred meanings as defined for formula I above.

If A ¹ , A ² , Z ¹ and Z ² occur twice in the formulas IA-5 and IA-6, they can each have the same or different meanings.

worin
R¹, R², A¹, A², L¹, L², Z¹, Z² und Y die gleichen sowie die gleichen bevorzugten Bedeutungen, wie für Formel I oben definiert, besitzen. Soweit A¹, A², Z¹ beziehungsweise Z² in den Formeln IA-7 bis IA-10 mehr als einmal vorkommen, können sie jeweils die gleiche oder verschiedene Bedeutungen aufweisen.
Besonders bevorzugt sind erfindungsgemäße Verbindungen der Formeln IA-1, IA-2, IA-3, IA-4, IA-5 und IA-6 insbesondere der Formeln IA-1, IA-2, IA-3, IA-5 und IA-6.Preferred compounds of formula I or IA, for which applies: m + n = 3, are represented by the following formulas:

wherein
R ¹ , R ² , A ¹ , A ² , L ¹ , L ² , Z ¹ , Z ² and Y have the same and the same preferred meanings as defined for formula I above. If A ¹ , A ² , Z ¹ or Z ² occurs more than once in the formulas IA-7 to IA-10, they can each have the same or different meanings.
Particularly preferred are compounds according to the invention of the formulas IA-1, IA-2, IA-3, IA-4, IA-5 and IA-6, in particular of the formulas IA-1, IA-2, IA-3, IA-5 and IA -6.

worin
R¹, R² einen Alkyl- oder Alkoxyrest mit bis zu 8 C-Atomen bedeutet.Very particularly preferred compounds of the formula IA-1 are the following:

wherein
R ¹ , R ² is an alkyl or alkoxy radical having up to 8 carbon atoms.

jeweils unabhängig voneinander bevorzugt einen Molekülteil der Formeln

oder

und besonders bevorzugt

oder

Above and below in the sub-formula means the part of the molecule

each independently preferably a part of the molecule of the formulas

or

and particularly preferred

or

If p occurs several times in the formulas, it can have the same or different meanings, generally 0, 1 or 2.

worin
R¹, R² und p die gleichen Bedeutungen wie oben definiert besitzen.Among the compounds of the formula IA-2 according to the invention, the following are particularly preferred:

wherein
R ¹ , R ² and p have the same meanings as defined above.

worin
R¹, R² und p die gleichen Bedeutungen wie oben definiert besitzen.Among the preferred compounds of the formula IA-3 according to the invention, the following are particularly preferred:

wherein
R ¹ , R ² and p have the same meanings as defined above.

worin
R¹, R² und p die gleichen Bedeutungen wie oben definiert besitzen. Soweit p in den Formeln mehrmals vorkommt, kann es jeweils die gleiche oder verschiedene Bedeutung aufweisen.Among the preferred compounds of the formula IA-4 according to the invention, the following are particularly preferred:

wherein
R ¹ , R ² and p have the same meanings as defined above. If p occurs several times in the formulas, it can have the same or different meanings in each case.

worin
R¹, R² und p die gleichen Bedeutungen wie oben definiert besitzen. Soweit p in den Formeln mehrmals vorkommt, kann es jeweils die gleiche oder verschiedene Bedeutung aufweisen.Among the preferred compounds of the formula IA-5 according to the invention, the following are particularly preferred:

wherein
R ¹ , R ² and p have the same meanings as defined above. If p occurs several times in the formulas, it can have the same or different meanings in each case.

worin
R¹, R² und p die gleichen Bedeutungen wie oben definiert besitzen. Soweit p in den Formeln mehrmals vorkommt, kann es jeweils die gleiche oder verschiedene Bedeutung aufweisen.Among the preferred compounds of the formula IA-6 according to the invention, the following are particularly preferred:

wherein
R ¹ , R ² and p have the same meanings as defined above. If p occurs several times in the formulas, it can have the same or different meanings in each case.

If radicals or substituents of the compounds according to the invention or the compounds according to the invention themselves are present as optically active or stereoisomeric radicals, substituents or compounds because they have an asymmetric center, for example, then these are also included in the present invention. It goes without saying that the compounds of the general formula I according to the invention can be used in pure isomeric form, for example as pure enantiomers, diastereomers, E or Z isomers, trans or cis isomers, or as a mixture of several isomers in any desired ratio, for Example as a racemate, E / Z isomer mixture or as a cis / trans isomer mixture.

ist in den erfindungsgemäßen Verbindungen und in den übrigen Komponenten für flüssigkristalline Medien bevorzugt trans-konfiguriert, d.h. die beiden Substituenten befindend sich in der thermodynamisch bevorzugten Sesselkonformation beide in äquatorialer Position.The 1,4-substituted cyclohexyl ring of formula

is preferably trans-configured in the compounds according to the invention and in the other components for liquid-crystalline media, ie the two substituents are both in the equatorial position in the thermodynamically preferred chair conformation.

Synthesis of the compounds:

The compounds of the general formula I can be prepared by methods known per se, as described in the literature (e.g. in standard works such as Houben-Weyl, Methods of Organic Chemistry, Georg-Thieme-Verlag, Stuttgart). under reaction conditions which are known and suitable for the reactions mentioned. It is possible to make use of variants that are known per se and are not mentioned in more detail here.

If appropriate, the starting materials can also be formed in situ in such a way that they are not isolated from the reaction mixture but are immediately further reacted to give 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 can be obtained according to generally accessible literature or can be purchased. The reaction types described are to be regarded as basically known from the literature.

Particularly suitable synthetic routes to the compounds according to the invention are explained below with reference to Schemes I to XXIII.

The compounds of the formula I are preferably synthesized starting from the naphthol derivatives 7 (cf. Scheme I). These are first halogenated in a suitable manner, X preferably being Br. In a preferred process (cf. Scheme I, Method A), the MOM ethers of substances 7 are prepared first. These are selectively metalated in the ortho position with n-butyllithium, and the organolithium compounds are trapped with the corresponding halogen (Br ₂ or I ₂ ). Finally, the MOM group is cleaved to give the halonaphthols 8. The ortho-metalation is analogous to the methods in a) F. Mongin, M. Schlosser, Tetrahedron Lett. 1996, 37, 6551-6554; b) RC Ronald, MR Winkle, Tetrahedron 1983, 39, 2031-2042; c) MR Winkle, RC Ronald, J. Org. Chem. 1982, 47, 2101-2108; d) M. Dabowski et al. Tetrahedron 2005, 61, 6590-6595 or e) PL Coe et al. J.Chem.Soc. Perkin Trans. 1 1995, 2729-2737.

Schema I: Synthese der Verbindungen der Formel I worin Y¹-Y² = >CH=CH₂-.The halogenation can also be carried out directly by treatment with iodine (X = I) or bromine (X = Br) in the presence of a base (cf. Scheme I, method B) (cf. a) CW Holzapfel, DBG Williams, Tetrahedron 1995, 51 , 8555-8564; b) KJ Edgar, SN Falling, J. Org. Chem. 1990, 55, 5287-5291; c) R. Johnsson, A. Meijer, U. Ellervik, Tetrahedron 2005, 61, 11567-11663).

Scheme I: Synthesis of the compounds of formula I wherein Y ¹ -Y ² =>CH=CH ₂ -.

A Sonogashira coupling of the halonaphthols 8 with terminal alkynes 9 under the respective reaction conditions generally initially gives the compounds 10. Depending on the reaction conditions (in particular the temperature) and depending on the nature of the alkyne 9, the cyclization products can be present either partially or exclusively of the formula I are formed. The (complete) cyclization of the compounds 10 to give the compounds of the formula I—or a precursor thereof—is finally achieved by reaction with diethylzinc in toluene under reflux (analogously to M. Nakmura, L. Ilies, S. Otsubo, E. Nakamura, Angew. Chem 2006, 118, 958-961 or Angew Chem Int Ed 2006, 45, 944-947).

The synthesis can be adapted to the compounds of the formula I desired in each case by choosing suitable starting materials 7 and 9 . Suitable terminal alkynes 9 are either commercially available or they can be synthesized following previously published methods.

The synthesis of the starting materials 7 is explained below using a few representative selected sub-formulae 7a to 7i.

Schema II: Synthese der Verbindungen 7 mit B = Cyclohexyl und L¹ = L² = F. (= 7a)If the ring B in the compounds of the formula I represents a cyclohexyl radical and if L ¹ and L ² are both F, the synthesis of the compounds 7 (or here the compounds 7a) begins with the compound 11, the synthesis of which WO 2004/029015 A1 disclosed (see Scheme II).

Scheme II: Synthesis of compounds 7 with B = cyclohexyl and L ¹ = L ² = F. (= 7a)

The functionalization of the β-tetralone 11 begins with the cerium(III) chloride-mediated addition of corresponding Grignard or organolithium compounds (cf. a) N. Takeda, T. Imamoto, Org. Synth. 1999, 76, 228-238; b) M. Scommoda et al. J Org Chem 1996, 61, 4379-4390). In the elimination by treatment with mesyl chloride and DBU (cf. M. Scommoda et al. above), the compounds 13 are obtained as the main component in the isomer mixture. These are hydrogenated to the corresponding tetrahydronaphthalenes 14, which are then converted to the tetrahydronaphthols 7a via the reaction sequence of ortho-metalation and hydrolysis and oxidation of the boronic acid ester formed in situ.

If the ring B in the compounds of the formula I according to the invention is to represent a cyclohexenyl radical, and if L ¹ and L ² are both to be F, the latter reaction sequence is carried out using the intermediates 13 in order to give the corresponding starting materials 7 (= 7c in Scheme VII) to get.

Schema III: Synthese der Verbindungen 7 mit Ring B = Cyclohexyl und L¹= H oder F und L² = H oder F (= 7b) Analog zu Schema II werden dazu die Verbindungen 15 (6-Methoxy-naphthalin-2-one) zunächst durch eine Cer(III)-chlorid-vermittelte Addition entsprechender Grignard- oder lithiumorganischer Verbindungen (vgl. oben) funktionalisiert. Wiederum werden bei der Eliminierung (vgl. oben) die Verbindungen 17 als Hauptkomponenten in den Isomerengemischen erhalten. Deren Hydrierung ergibt 6-Methoxy-1,2,3,4-tetrahydronaphthaline 18. Abschließend wird der Methylether mit Bortribromid gespalten (vgl. a) J. F. W. McOmie, D. E. West, Org. Synth., Coll. Vol. V 1973, 412; b) E. H. Vickery, L. F. Pahler, E. J. Eisenbraun, J. Org. Chem. 1979, 44, 4444-4446).If the ring B in the compounds of the formula I according to the invention represents a cyclohexyl radical and if one of the substituents L ¹ and/or L ² is H, then the compounds 7 are synthesized starting from the compounds 15. In 15 L ¹ or L is preferred ² H, the other substituent F.

Scheme III: Synthesis of the compounds 7 with ring B = cyclohexyl and L ¹ = H or F and L ² = H or F (= 7b) Analogously to Scheme II, the compounds 15 (6-methoxy-naphthalene-2-one) first functionalized by a cerium(III) chloride-mediated addition of corresponding Grignard or lithium-organic compounds (see above). Once again, the compounds 17 are obtained as the main components in the isomer mixtures in the elimination (cf. above). Hydrogenation of these gives 6-methoxy-1,2,3,4-tetrahydronaphthalenes 18. Finally, the methyl ether is cleaved with boron tribromide (cf. a) JFW McOmie, DE West, Org. Synth., Coll. Vol V 1973, 412; b) EH Vickery, LF Pahler, EJ Eisenbraun, J. Org. Chem. 1979, 44, 4444-4446).

If the ring B in the compounds 7 is to represent a cyclohexenyl radical and L ¹ and/or L ² are to be H, the methyl ether cleavage is carried out using the intermediates 17 in order to obtain the corresponding starting materials 7 (=7d in scheme X). .

Schema IV: Synthese von 7 -Fluor-6-methoxy-3,4-dihydro-1 H-naphthalin-2-on 15a und 8-Fluor-6-methoxy-3,4-dihydro-1H-naphthalin-2-on 15bFor the synthetic sequences outlined in Scheme III, where only one of the substituents L ¹ or L ² is F and the remaining substituent is hydrogen, the starting materials become 7-fluoro-6-methoxy-3,4-dihydro-1H -naphthalen-2-one 15a (= 15 with L ¹ = F, L ² = H) and 8-Fluoro-6-methoxy-3,4-dihydro-1 H-naphthalen-2-one 15b (= 15 with L ¹ = H, L ² = F) is required (see Scheme IV). These are also with the in the WO 2004/029015 A1 method used from 3-fluoro-4-methoxy-phenylacetic acid 19 or 2-fluoro-4-methoxy-phenylacetic acid 20 prepared.

Scheme IV: Synthesis of 7-Fluoro-6-methoxy-3,4-dihydro-1H-naphthalen-2-one 15a and 8-Fluoro-6-methoxy-3,4-dihydro-1H-naphthalen-2-one 15b

The synthesis of 3-fluoro-4-methoxy-phenylacetic acid 19 from 2-fluoroanisole was reported by M. Kuchar et al. (Collect. Czech. Chem. Commun. 1990, 55, 296-306). 2-Fluoro-4-methoxy-phenylacetic acid 20 is prepared from 2-fluoro-4-hydroxy-phenylacetic acid [S.-I. Sugita, S. Toda, T. Yoshiyasu, T. Teraji, Mol. Cryst. Liq. Cryst. 1993, 237, 399-406; EJ Corey, JP Dittami, J. Am. Chem. Soc. 1985, 107, 256-257; HH Wassermann, J. Wang, J. Org. Chem. 1998, 63, 5581-5586] by dimethylation and ester saponification.

Non-fluorinated synthetic building blocks 7 (with L ¹ = L ² = H) are obtained starting from 6-methoxy-3,4-dihydro-1H-naphthalen-2-one 15 (with L ¹ = L ² = H). A synthesis of 6-methoxy-3,4-dihydro-1H-naphthalen-2-one 15 (with L ¹ = L ² = H) is described in SN Suryawanshi, SN Fuchs, J. Org. Chem. 1986, 51, 902-921.

Schema V: Synthese der Verbindung 21 und der Verbindungen 22.Another particularly preferred synthesis of the compounds 7 starts from the compound 21 or the compounds 22. The synthesis of 21 takes place starting from 11 by generating the enol ether and reacting it with trifluoroacetic anhydride. Compounds 22 are prepared analogously from compounds 15 (see Scheme V).

Scheme V: Synthesis of compound 21 and compounds 22.

Schema VI: Beispiele für Kreuzkupplungen mit dem Enoltriflat 21.The enol triflates 21 and 22 can be used in transition metal mediated cross-coupling reactions [cf. Metal-catalyzed Cross-coupling Reactions (Eds.: A. de Meijre, F. Diederich), Wiley-VCH, Weinheim, 2nd edition 2004] can be functionalized in a variety of ways (cf. Scheme VI and Scheme IX). Cross-coupling with aryl boronic acids 23 (Suzuki couplings), alkenyl boronic acids 25 and 27 [C. Sun, R. Bittman, J. Org. Chem. 2006, 71, 2200-2202 and A. Torrado, S. Lopez, R. Alvarez, AR de Lera, Synthesis 1995, 285-293], other boronic acids 29 [T. Oh-e, N. Miyaura, A. Suzuki, J. Org. Chem. 1993, 58, 2201-2208], Grignard reagents 30 [B. Scheiper, M. Bonnekessel, H. Krause, A. Fürstner, J. Org. Chem. 2004, 69, 3943-3949] and terminal alkynes 31 [Y. Zhao, K. Campbell, RR Tykwinski, J. Org. Chem. 2002, 67, 336-344.] particularly preferred methods to obtain functionalized dihydronaphthalene derivatives 13 (and more general formulas) and 17 (and more general formulas). Some examples of cross-coupling reactions of the enol triflate 21 are shown in Scheme VI.

Scheme VI: Examples of cross-coupling with the enol triflate 21.

The products 13 (general formula) from this functionalization are converted into the desired compounds 7 as shown again in Scheme VII and Scheme VIII (cf. also Scheme II).

Schema VII: Synthese der Verbindungen 7 mit B = Cyclohexenyl und L¹ = L² = F (= 7c)If ring B in the compounds of the formula I according to the invention is to be a cyclohexenyl radical, the compounds 13 are converted to the dihydronaphthols 7c via the reaction sequence ortho-metalation and hydrolysis and oxidation of the boronic acid ester formed in situ (cf. Scheme VII).

Scheme VII: Synthesis of compounds 7 with B = cyclohexenyl and L ¹ = L ² = F (= 7c)

Schema VIII: Synthese der Verbindungen 7 mit B = Cyclohexyl und L¹ = L² = F (= 7a)If there is a cyclohexyl radical in the compounds of the formula IB according to the invention, the compounds 13 are first hydrogenated to give the compounds 14 and then reacted as above to give the corresponding tetrahydronaphthols 7a (cf. Scheme VIII).

Scheme VIII: Synthesis of compounds 7 with B = cyclohexyl and L ¹ = L ² = F (= 7a)

Schema IX: Beispiele für Kreuzkupplungen mit den Enoltriflaten 22.Some examples of cross-coupling reactions of enol triflates 22 are shown in Scheme IX below.

Scheme IX: Examples of cross-coupling with the enol triflates 22.

The products 17 (general formula) from this functionalization are converted into the desired compounds 7 as shown again in Scheme X and Scheme XI (cf. also Scheme III).

Schema X: Synthese der Verbindungen 7 mit B = Cyclohexenyl und L¹= H oder F und L² = H oder F (= 7d)If the ring B in the compounds 7 is to be a cyclohexenyl radical and L ¹ and/or L ² are to be H, then a methyl ether cleavage is carried out using the intermediates 17 in order to obtain the corresponding starting materials 7d (cf. Scheme X).

Scheme X: Synthesis of compounds 7 with B = cyclohexenyl and L ¹ = H or F and L ² = H or F (= 7d)

Schema XI: Synthese der Verbindungen 7 mit B = Cyclohexyl und L¹= H oder F und L² = H oder F (= 7b)If ring B in compounds 7 is to represent a cyclohexyl radical and L ¹ and/or L ² are to be H or F, hydrogenation to give compounds 18 is carried out before the methyl ether cleavage (cf. Scheme XI).

Scheme XI: Synthesis of compounds 7 with B = cyclohexyl and L ¹ = H or F and L ² = H or F (= 7b)

If the ring B in the compounds of the formula I represents a phenyl radical (L ³ = H) or a fluorinated phenyl radical (L ³ = F) (cf. Scheme XII) and if L ¹ and L ² are both F, then the synthesis proceeds from the compounds 37 (L ³ = H or F), whose synthesis the publication WO 2004/029015 A1 disclosed.

Schema XII: Synthese der Triflate 38 aus den Verbindungen 37.These intermediates 37 and the resulting triflates 38 (cf. Scheme XII) can be functionalized in many ways (cf. Schemes XIII, XIV and XV).

Scheme XII: Synthesis of triflates 38 from compounds 37.

Schema XIII: Veretherung der Verbindungen 37 zu Verbindungen 40.If R ² -(A ² -Z ² ) _n - is to represent an alkoxy radical, 37 is simply etherified with alkyl iodides or bromides (cf. Scheme XIII).

Scheme XIII: Etherification of compounds 37 to compounds 40.

Schema XIV: Kupplung der Triflate 38 mit Alkenylboronsäuren und anschließender Hydrierung zu den Verbindungen 42.If R ² -(A ² -Z ² ) _n - is to represent an alkenyl radical, the triflates of compounds 37 are reacted with corresponding alkenylboronic acids in a palladium-catalyzed cross-coupling (cf. a) C. Sun, R. Bittmann , J. Org. Chem. 2006, 71, 2200-2202; b) A. Torrado, S. Lopez, R. Alvarez, AR de Lera, Synthesis 1995, 285-293). Optionally, these alkenyls 41 can also be converted to the corresponding saturated compounds 42 by hydrogenation (see Scheme XIV).

Scheme XIV: Coupling of triflates 38 with alkenyl boronic acids and subsequent hydrogenation to give compounds 42.

Schema XV: Funktionalisierung der Triflate 38 durch Kreuzkupplungsreaktionen, hier am Beispiel einer Kupplung mit einem Grignard-Reagenz dargestellt.Furthermore, transition-metal-mediated cross-coupling reactions of triflates 38, e.g. B. with aryl boronic acids (Suzuki coupling), terminal alkynes (Sonogashira coupling) and Grignard reagents (Kumada coupling or iron(III)-mediated cross-coupling; cf. Scheme XV, here only the functionalization via a coupling with Grignard Reagents shown; for further functionalization options, see Scheme VI and Scheme IX) particularly preferred methods for obtaining further functionalized naphthalene derivatives 43.

Scheme XV: Functionalization of the triflate 38 by cross-coupling reactions, shown here for a coupling with a Grignard reagent.

Schema XVI: Synthese der Verbindungen 7 mit B = Phenyl, L¹ = L² = F und L³ = H oder F (= 7e).These functionalized naphthalene derivatives 43 (general formula) are then reacted again via the reaction sequence of ortho-metalation, generation of a boronic acid ester and hydrolysis and oxidation thereof to form the naphthols 7 (=7e) (cf. Scheme XVI). These naphthols 31 are then processed further as shown in Scheme I.

Scheme XVI: Synthesis of compounds 7 with B = phenyl, L ¹ = L ² = F and L ³ = H or F (= 7e).

Schema XVII: Synthese der Verbindungen 7 mit B = Phenyl, L¹ = H oder F und L² = H oder F und L³ = H (= 7f).If the ring B in the compounds of the formula I represents a non-fluorinated phenyl radical (L ³ = H) and L ¹ and/or L ² is H, the substituent L ¹ or L ² which is not H being preferably F, the synthesis of the compounds 7 (here 7f) proceeds from the compounds 17 (cf. Scheme XVII). The synthesis of compounds 17 has already been presented above.

Scheme XVII: Synthesis of compounds 7 with B = phenyl, L ¹ = H or F and L ² = H or F and L ³ = H (= 7f).

The tetralones 17 are converted into the corresponding naphthols 44 by treatment with bromine (cf. WO 2004/029015 A1 ).

The resulting triflates 45 from 44 can then be functionalized in a variety of ways as previously described for 38 above (see Scheme XIV and Scheme XV). Only the functionalization of 45 via a Kumada coupling is shown in Scheme XVII. Further reactions of the triflates 45 are possible as previously described (compare Scheme VI and Scheme IX). After cleavage of the methyl ether 46, the starting materials 7f required for further reactions (cf. Scheme I) are available.

Schema XVIII: Synthese der Verbindungen 7 mit B = Phenyl und L¹ = H oder und L² = H oder F und L³ = H und R²-A²-Z² = Alkoxy (= 7g).If R ² -(A ² -Z ² ) _n - in 7f is to represent an alkoxy radical, the synthesis has to be modified. On the one hand, in the last step of the synthesis of the compounds 7f (cf. Scheme XVII), methods can be used which allow the cleavage of aryl methyl ethers in the presence of other alkyl aryl ethers (AK Chakraborti et al. J. Org. Chem. 2002, 67, 6406-6414; G 1994, 35, 8727-8730, E. Duran et al -1577) allow. An alternative preferred process is outlined in Scheme XVIII. Here, the intermediate products 7g are synthesized starting from bromotetralones 47. These are in turn converted into the corresponding 6-bromonaphthalen-2-ols 48 by treatment with bromine (cf. WO 2004/029015 A1), which are then converted into the desired ethers 50 can. The conversion to the desired naphthols 7g is then initiated via a metalation of the compounds 50 with Mg, Grignard or organolithium compounds.

Scheme XVIII: Synthesis of the compounds 7 with B = phenyl and L ¹ = H or and L ² = H or F and L ³ = H and R ² -A ² -Z ² = alkoxy (= 7g).

Schema XIX: Synthese von substituierten 4-Bromtetralonen 47.The synthesis of the bromotetralones 47 is carried out in accordance with the literature, starting from substituted 4-bromotoluenes 51 (cf. Scheme XIX, WO 2004/029015 A1 ; MT Konieczny et al. Synthesis 2005, 1575-1577; BP Imbimbo et al., J.Med.Chem. 2005, 48, 5705-5720). 4-Bromo-3-fluorotoluene (51, ^L1 = F, ^L2 = H) and 4-bromo-2-fluorotoluene (51, ^L1 = H, ^L2 = F) are commercially available. The methyl group of the bromotoluenes 51 is first brominated with NBS and the bromomethylene compounds 52 are converted into the corresponding nitriles with potassium cyanide. These are then hydrolyzed to the phenylacetic acids 53, which are then converted to the desired bromotetralones 47.

Scheme XIX: Synthesis of substituted 4-bromotetralones 47.

A synthesis of the non-fluorinated building block 47 (L ¹ = L ² = H) is reported by DM Tschaen et al. J. Org. Chem. 1995, 60, 4324-4330.

Schema XX: Synthese der Verbindungen 7 mit B = Phenyl und L¹ = H oder F und L² = H oder F und L³ = F und R²-A²-Z² = Alkoxy (= 7h).If the ring B in the compounds of the formula I represents a fluorinated phenyl radical (L ³ = F) and L ¹ and/or L ² are H, the substituent L ¹ or L ² which is not H being preferably F, so the synthesis of the compounds 7 (especially 7h and 7i) is also advantageously carried out starting from the bromonaphthols 48 (cf. Scheme XX and Scheme XXI).

Scheme XX: Synthesis of the compounds 7 with B = phenyl and L ¹ = H or F and L ² = H or F and L ³ = F and R ² -A ² -Z ² = alkoxy (= 7h).

The naphthols 48 are first converted to the difluoro-1H-naphthalen-2-ones 54 by fluorination with Selectfluor ^® (F-TEDA-BF ₄ ) (cf. WO 2004/029015 A1 ), which are then reduced to 1H-naphthalen-2-ols 55. On treatment with base, these rearomatize to give the compounds 56 with elimination of hydrogen fluoride. The compounds 56 are then also central intermediates for the synthesis of compounds in which R ² -A ² -Z ² is intended to represent an alkoxy radical. (Scheme XX, last reaction) For this purpose, it is first etherified with suitable alkyl halides and then the conversion to the naphthol 7h is carried out.

Schema XXI: Synthese der Verbindungen 7 mit B = Phenyl und L¹ = H oder F und L² = H oder F und L³ = F (= 7i).Starting from 56, functionalization via the triflate 57 can take place. In the cross-coupling shown (cf. Scheme XXI) with various Grignard reagents, effective discrimination between the triflate and the bromine function is possible [T. Kamikawa, T. Hayashi, Tetrahedron Lett. 1997, 38, 7087-7090]. After conversion of 48 to the naphthol 7i, the starting materials 7 (especially 7i) required for the further synthesis (cf. Scheme I) are available.

Scheme XXI: Synthesis of compounds 7 with B = phenyl and L ¹ = H or F and L ² = H or F and L ³ = F (= 7i).

Schema XXII: Synthese der Verbindungen der Formel I' aus I, in denen Y¹-Y² = >CH-CH₂- bedeutet.Compounds of the formula I according to the invention in which Y ¹ -Y ² = >CH-CH ₂ -(here I') are obtained directly by hydrogenation from the compounds of the formula I in which Y ¹ -Y ² = >CH=CH- is (see Scheme XXII).

Scheme XXII: Synthesis of the compounds of the formula I' from I in which Y ¹ is -Y ² = >CH-CH ₂ -.

If compounds of the formula I are to be synthesized in which Y ¹ -Y ² = >CH-CH ₂ - means (I') and B is cyclohexenyl and/or R ¹ -A ¹ -Z ¹ and/or R ² -A ² -Z ² contain one or more unsaturated radicals, bridge members or ring systems, the following process is preferred (cf. Scheme XXIII).

Schema XXIII: Synthese der Verbindungen der Formel I in denen Y¹-Y² = >CH-CH₂- bedeutet (hier speziell Verbindungen I') und die eine oder mehrere ungesättigte Reste, Brückenglieder oder Ringsysteme enthalten.Based on the literature a) JC Gonzälez-Gömez, L. Santana, E. Uriarte, Tetrahedron 2005, 61, 4805-4810 and b) KJ Hodgetts, Tetrahedron 2005, 61, 6860-6870 the construction of the saturated O-heterocycle starts from from the compounds of formula 8 (Scheme XXIII, X = Br is particularly preferred). Etherification with bromoethanol derivatives 52 affords compounds 53 (X = Br). The Grignard reagent generated from these compounds spontaneously cyclizes under the reaction conditions to form 51.

Scheme XXIII: Synthesis of the compounds of the formula I in which Y ¹ -Y ² = >CH-CH ₂ - (here specifically compounds I') and which contain one or more unsaturated radicals, bridge members or ring systems.

The reaction schemes shown are only to be understood as examples. The person skilled in the art can make appropriate variations of the syntheses presented and can also use other suitable synthetic routes in order to obtain compounds of the formula I. Individual substituents (e.g. H or F) and parts of the molecule in the formulas 2 to 59 can generally be extended by the definitions of the corresponding substituents and parts of the molecule of the formula I, insofar as the compounds of the formula I are defined more generally. According to formula I, the molecule group Z ² is adjacent to the ring B or is adjacent to a ring A ² on the left-hand side; in the event that Z ² in the formula is not adjacent to a ring on the left-hand side, then Z ² is a single bond.

worin
m, n, A¹, Z¹, A² und Z² wie für Formel I oben definiert sind, und R¹¹ und R²² wie R¹ definiert sind und zusätzlich -OTosyl, -OTriflat, -OMesyl oder -B(OH)₂ oder -B(OAlkyl)₂ oder -B<(-O-C_2-10-AlkylenO-) bedeuten,A partial aspect of the invention are processes for preparing the compounds of the formula I according to the invention. The invention therefore relates to a process for preparing compounds of the formula I, characterized in that it comprises a process step in which a compound of the formula (10)

wherein
m, n, A ¹ , Z ¹ , A ² and Z ² are as defined for formula I above, and R ¹¹ and R ²² are defined as R ¹ and additionally -OTosyl, -OTriflate, -OMesyl or -B(OH) ₂ or -B(Oalkyl) ₂ or -B<(-OC _2-10 -alkyleneO-),

is cyclized in the presence of a base [partially not according to the claims]. According to the invention, the compound (10) is cyclized to a naphthofuran compound, i.e. a tricyclic compound analogous to the formula I. The products of the process are preferably a compound of the formula I or a synthetic precursor thereof, in particular a compound of the formula I.

Naphthofuran compounds within the meaning of the invention are compounds with a tricyclic ring system as described as part of formula I. Accordingly, naphthofuran compounds also include the partially hydrogenated species such as tetrahydro-naphthofurans, etc., as well as all substituted variants. The term naphthofuran compound also designates compounds which do not come under formula I, independently of the substitution of the ring system.

The products of the process are naphthofuran compounds having a tricyclic ring system, which fall under the compounds of formula I or can serve as synthetic intermediates for the synthesis of compounds of formula I.

An alkyl metal compound is preferably used as the base, in particular diethyl zinc.

Further details on the process can be found in the examples, the parameters of which are representative of the process according to the invention. The person skilled in the art will be able to find individual reaction conditions from the examples, to generalize them or to adapt them to the individual case.

As already mentioned, the compounds of the general formula I can be used in liquid-crystalline media.

The subject matter of the present invention is therefore also a liquid-crystalline medium with at least two liquid-crystalline compounds containing at least one compound of the general formula I.

The present invention also relates to liquid-crystalline media containing, in addition to one or more compounds of the formula I according to the invention, as further constituents 2 to 40, preferably 4 to 30 components. These media particularly preferably contain 7 to 25 components in addition to one or more compounds according to the invention. These other components are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, 1,3-dioxanes, 2,5-tetrahydropyrans, phenyl or cyclohexyl benzoates, cyclohexanecarboxylic acid phenyl or-cyclohexyl ester, phenyl or cyclohexyl ester of cyclohexylbenzoic acid, phenyl or cyclohexyl ester of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl ester of benzoic acid, cyclohexanecarboxylic acid or cyclohexylcyclohexanecarboxylic acid, phenylcyclohexane, cyclohexylbiphenyl, phenylcyclohexylcyclohexane, cyclohexylcyclohexane, cyclohexylcyclohexylcyclohexene, 1,4-biscyclohexylbenzo le, 4',4 '-Biscyclohexylbiphenyls, phenyl or cyclohexylpyrimidines, phenyl or cyclohexylpyridines, phenyl or cyclohexyldioxanes, phenyl or cyclohexyl-1,3-dithianes, 1,2-diphenylethanes, 1,2-dicyclohexylethanes, 1-phenyl-2-cyclohexylethanes, 1-cyclohexyl-2-(4-phenylcyclohexyl)ethanes, 1-cyclohexyl-2-biphenylethanes, 1-phenyl-2-cyclohexylphenylethanes, optionally halogenated stilbenes, benzylphenyl ethers, tolanes and substituted cinnamic acids. The 1,4-phenylene groups in these compounds can also be singly or multiply fluorinated.

The most important compounds that are suitable as further components of media according to the invention can be characterized by the formulas (II), (III), (IV), (V) and (VI): R'-LE-R'' (II) R'-L-COO-E-R'' (III) R'-L-OOC-E-R'' (IV) R'-L-CH ₂ CH ₂ -E-R'' (V) R'-L-CF ₂ OE-R'' (VI)

In the formulas (II), (III), (IV), (V) and (VI), L and E, which may be the same or different, each independently represent a divalent radical selected from the group consisting of -Phe-, -Cyc- , -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -Thp-, -G-Phe- and -G-Cyc- and their mirror images, where Phe unsubstituted or fluorine-substituted 1,4-phenylene, cyclohexylene or 1,4-cyclohexenylene, pyr, pyrimidine-2,5-diyl or pyridine-2,5-diyl, dio 1,3-dioxane- 2,5-diyl, Thp tetrahydropyran-2,5-diyl and G 2-(trans-1,4-cyclohexyl)-ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3- dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.

Preferably, one of L and E is Cyc or Phe. E is preferably Cyc, Phe or Phe-Cyc. The media according to the invention preferably contain one or more components selected from the compounds of the formulas (II), (III), (IV), (V) and (VI), in which L and E are selected from the group Cyc and Phe and at the same time one or several components selected from the compounds of the formulas (II), (III), (IV), (V) and (VI), in which one of the radicals L and E is selected from the group Cyc and Phe 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 the formulas (II), ( III), (IV), (V) and (VI), wherein the residues 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 (II), (III), (IV), (V) and (VI) each independently represent alkyl, alkenyl, alkoxy, alkoxyalkyl (oxaalkyl), alkenyloxy or Alkanoyloxy with up to 8 carbon atoms. This smaller subgroup is called group A below and the compounds are designated by the partial formulas (IIa), (IIIa), (IVa), (Va) and (VIa). In most of these compounds, R' and R'' are different from one another, with one of these radicals usually being alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In another minor subgroup of compounds of formulas (II), (III), (IV), (V) and (VI) referred to as Group B, E

In the compounds of group B, which are denoted by the partial formulas (IIb), (IIIb), (IVb), (Vb) and (Vlb), R' and R" have the compounds of the partial formulas (IIa) to ( VIa) given meaning and are preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In another smaller subgroup of the compounds of the formulas (II), (III), (IV), (V) and (VI), R'' is -CN. This subgroup is referred to below as group C and the compounds of this subgroup are correspondingly described with partial formulas (IIc), (IIIc), (IVc), (Vc) and (VIc). In the compounds of the partial formulas (IIc), (IIIc), (IVc), (Vc) and (VIc), R' has the meaning given for the compounds of the partial formulas (IIa) to (VIa) and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

In addition to the preferred compounds of groups A, B and C, other compounds of the formulas (II), (III), (IV), (V) and (VI) with other variants of the intended substituents are also customary. All of these substances can be obtained by methods known from the literature or analogously thereto.

• Gruppe A: 0 bis 90 %, vorzugsweise 20 bis 90 %, insbesondere 30 bis 90 %.
• Gruppe B: 0 bis 80 %, vorzugsweise 10 bis 80 %, insbesondere 10 bis 70 %.
• Gruppe C: 0 bis 80 %, vorzugsweise 5 bis 80 %, insbesondere 5 bis 50 %.

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

• Group A: 0 to 90%, preferably 20 to 90%, especially 30 to 90%.
• Group B: 0 to 80%, preferably 10 to 80%, especially 10 to 70%.
• Group C: 0 to 80%, preferably 5 to 80%, especially 5 to 50%.

The media according to the invention preferably contain 1 to 40%, particularly preferably 5 to 30%, of the compounds of the formula I according to the invention. Media containing more are also preferred than 40%, in particular 45 to 90% of compounds of the formula I according to the invention. The media preferably contain one, two, three, four or five compounds of the formula I according to the invention.

mit R^a, R^b unabhängig voneinander -C_pH_2p+1 oder -OC_pH_2p+1 und p = 1, 2, 3, 4, 5, 6, 7 oder 8 sowie L¹, L² unabhängig voneinander -H oder -F,

mit m, n unabhängig voneinander 1, 2, 3, 4, 5, 6, 7 oder 8.Examples of the compounds of formulas (II), (III), (IV), (V) and (VI) are the compounds listed below:

with R ^a , R ^b independently of one another -C _p H _2p+1 or -OC _p H _2p+1 and p = 1, 2, 3, 4, 5, 6, 7 or 8 and L ¹ , L ² independently of one another - H or -F,

with m, n independently 1, 2, 3, 4, 5, 6, 7 or 8.

The media according to the invention are produced in a conventional manner. As a rule, the components are dissolved in one another, preferably at elevated temperature. The liquid-crystalline phases of the present invention can be modified by suitable additives in such a way that they can be used in all types of liquid-crystal display elements that have become known hitherto. 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 to produce colored guest-host systems or substances to change the dielectric anisotropy, the viscosity and/or the orientation of the nematic phases.

Because of 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 more detail below with reference to exemplary embodiments, but without intending to be restricted thereby.

• K: Kristalline Phase; N: Nematische Phase; Sm: Smektische Phase;
• I: Isotrope Phase; Tg Glas. Die Zahlen zwischen diesen Symbolen geben die Übergangstemperaturen der betreffenden Substanz wieder. Temperaturangaben sind, soweit nichts anderes angegeben, in °C.

In addition to the usual and well-known abbreviations, the following abbreviations are used:

• K: crystalline phase; N: nematic phase; Sm: smectic phase;
• I: isotropic phase; Tg glass. The numbers between these symbols represent the transition temperatures of the substance in question. Unless otherwise stated, temperatures are in °C.

The physical, physicochemical or electro-optical parameters are determined using generally known methods, as described in the brochure, among other things "Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurements Methods", 1998, Merck KGaA, Darmstadt.

Above and below, Δn means the optical anisotropy (589 nm, 20°C) and Δε means the dielectric anisotropy (1 kHz, 20°C). The dielectric anisotropy Δε is determined at 20° C. and 1 kHz. The optical anisotropy Δn is determined at 20° C. and a wavelength of 589.3 nm.

The Δε and Δn values, as well as the rotational viscosity (γ1) of the compounds according to the invention are obtained by linear extrapolation from liquid-crystalline mixtures which consist of 5 to 10% of the respective compound of the invention and 90-95% of the commercially available liquid-crystal mixture ZLI -2857 (for Δε) or ZLI-4792 (for Δn, γ1) (mixtures from Merck KGaA, Darmstadt).

The abbreviations above and below mean: MTBE methyl t-butyl ether THF tetrahydrofuran DMF dimethylformamide i. vac. In a vacuum (approx. 10 ^-2 bar) total saturated n-BuLi n-butyllithium, solution in hexane MOM methoxymethyl rt room temperature F-TEDA-BF ₄ 1-Chloromethyl-4-fluoro-1,4-diazabicyclo[2.2.2]octane bistetrafluoroborate TMP Tetramethylpiperidine dppp 1,3-bis(diphenylphosphine)propane tf triflate or trifluoromethanesulfonyl radical mesyl methanesulfonyl

examples

The starting substances can be obtained according to generally available literature or can be purchased.

Example 1: 4,5-Difluoro-7-propyl-2-(4-propyl-phenyl)-6,7,8,9-tetrahydronaphtho[2,1-b]furan

1.1 Preparation of 7,8-difluoro-2-propyl-1,2,3,4-tetrahydro-naphthalen-2-ol

74.5 g (0.20 mol) of cerium(III) chloride heptahydrate are prepared as described in the literature [N. Takeda, T. Imamoto, Org. Synth. 1999, 76, 228-238]. The now anhydrous cerium(III) chloride is suspended in 200 ml of THF at 5 °C by means of ultrasound, and the suspension is mixed with 100 ml of propylmagnesium chloride (0.20 mol, 2 M solution in Et ₂ O) at -15 °C. shifted. After 1.5 h at this temperature, 20.3 g (0.11 mol) of 7,8-difluoro-3,4-dihydro-1H-naphthalen-2-one are added dropwise as a solution in 200 ml of THF and the batch is 30 min stirred at RT. The mixture is hydrolyzed with dil. acetic acid and diluted with ethyl acetate. The organic phase is separated and the aqueous phase is extracted with ethyl acetate. The combined organic phases are washed with sat. sodium chloride solution washed and dried with sodium sulfate. The crude product (orange oil) obtained after removing the solvents is used directly for the following reaction.

1.2 Preparation of 5,6-difluoro-3-propyl-1,2-dihydro-naphthalene

78.0 g (about 0.21 mol) of crude 7,8-difluoro-2-propyl-1,2,3,4-tetrahydronaphthalen-2-ol are placed in 350 ml of pyridine and 40.0 ml (0. 44 mol) of phosphoryl chloride are added. The batch is heated to 80° C. for 30 minutes and then poured into water. The mixture is extracted several times with MTBE and the combined organic phases are washed with sat. sodium chloride solution washed. The solution is completely concentrated and the residue is purified by column chromatography (SiO ₂ , n-heptane). 5,6-difluoro-3-propyl-1,2-dihydro-naphthalene is obtained in the isomer mixture as a clear, colorless liquid.

1.3 Preparation of 7,8-difluoro-2-propyl-1,2,3,4-tetrahydro-naphthalene

32.8 g (0.16 mol) of the isomer mixture obtained above are hydrogenated in THF at RT and atmospheric pressure in the presence of Pd—C (5% Pd) for 30 h. The reaction solution is filtered and fully concentrated. The residue is purified by column chromatography (SiO ₂ , n-pentane). 7,8-Difluoro-2-propyl-1,2,3,4-tetrahydro-naphthalene is obtained as a clear, colorless liquid.

1.4 Preparation of 3,4-difluoro-6-propyl-5,6,7,8-tetrahydro-naphthalen-2-ol

31.0 g (0.15 mol) of 7,8-difluoro-2-propyl-1,2,3,4-tetrahydro-naphthalene are placed in 200 ml of THF and treated at -70 °C with 110.0 ml (0 .18 mol) n-BuLi (15% solution in hexane). After 3 hours at this temperature, 19.0 g (0.18 mol) of trimethyl borate in 50 ml of THF are added dropwise, and the batch is warmed to 0.degree. 45 ml of diluted acetic acid (approx. 30%) are added. The mixture is warmed to 30°C and 38 ml of hydrogen peroxide solution (35%) are carefully added. After the addition is complete, the mixture is stirred at RT for 17 h. Water is added and the batch is acidified with HCl. The solution is extracted several times with MTBE and the combined organic phases are washed successively with water, sat. sodium chloride solution and ammonium iron (II) sulfate solution. washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). 3,4-Difluoro-6-propyl-5,6,7,8-tetrahydro-naphthalen-2-ol is obtained as a yellowish oil.

1.5 Preparation of 7,8-difluoro-6-methoxymethoxy-2-propyl-1,2,3,4-tetrahydro-naphthalene

26.5 g (0.12 mol) of 3,4-difluoro-6-propyl-5,6,7,8-tetrahydro-naphthalen-2-ol are dissolved in 200 ml of dichloromethane and 23.8 ml (0.14 mmol) of N-ethyldiisopropylamine are added under ice cooling. After 5 minutes, 10.6 ml (97.0 mmol) of chloromethyl methyl ether are metered in at a temperature in the range from 5 to 14.degree. After 19 hours at 20° C., 50 ml of triethylamine are added and the mixture is stirred for 30 minutes. Water is added to the reaction mixture and the organic phase is separated off. The aqueous phase is extracted with dichloromethane and the combined organic phases are washed successively with water and sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). In this way, 7,8-difluoro-6-methoxymethoxy-2-propyl-1,2,3,4-tetrahydro-naphthalene is obtained as a water-white oil.

1.6 Preparation of 5-iodo-7,8-difluoro-6-methoxymethoxy-2-propyl-1,2,3,4-tetrahydro-naphthalene

19.8 g (73.2 mmol) of 7,8-difluoro-6-methoxymethoxy-2-propyl-1,2,3,4-tetrahydro-naphthalene are placed in 150 ml of THF and treated at -78° C. with 55 0 ml (87.6 mmol) n-BuLi (15% solution in hexane) was added dropwise. After the addition is complete, the mixture is stirred at this temperature for 30 min and then at 0° C. for 1 h. The solution is again cooled to -78°C and a solution of 22.3 g (87.9 mmol) of iodine in 100 ml of THF is added dropwise. The reaction mixture is stirred at -78° C. for 30 min and at 0° C. for 1 h. The batch is diluted with MTBE and the solution is made half-conc. sodium hydrogen sulfite solution shifted. The mixture is washed with water and with sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is used directly for the following reaction.

1.7 Preparation of 1-iodo-3,4-difluoro-6-propyl-5,6,7,8-tetrahydronaphthalen-2-ol

A solution of 26.0 g (ca. 65.6 mmol) of crude 5-iodo-7,8-difluoro-6-methoxymethoxy-2-propyl-1,2,3,4-tetrahydro-naphthalene in 150 mL of THF with 12.0 ml conc. HCl is added, and the mixture is stirred at 20° C. for 17 h. The batch is diluted with MTBE and the solution is washed with water. The aqueous phase is extracted with MTBE and the combined organic phases are washed with water and sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). There is thus obtained 1-iodo-3,4-difluoro-6-propyl-5,6,7,8-tetrahydro-naphthalen-2-ol as an orange solid.

1.8 Preparation of 4,5-difluoro-7-propyl-2-(4-propyl-phenyl)-6,7,8,9-tetrahydro-naphtho[2,1-b]furan

Δε = -5,6
Δn = 0,1958
γ₁ = 466 mPa·s
Tg -24 K 72 N (56) I5.4 g (15.3 mmol) of 1-iodo-3,4-difluoro-6-propyl-5,6,7,8-tetrahydro-naphthalen-2-ol together with 420 mg (0.6 mmol) Bis(triphenylphosphine)palladium(II) chloride, 114 mg (0.6 mmol) of copper(I) iodide and 5.0 ml (36.1 mmol) of triethylamine in 24 ml of DMF. The mixture is heated to 110°C and a solution of 2.21 g (15.3 mmol) of 1-ethynyl-4-propylbenzene in 16 ml of DMF is added dropwise. After one hour at this temperature, a further 0.6 g (4.2 mmol) of 1-ethynyl-4-propylbenzene are added and the mixture is heated for 1 hour. After cooling, the mixture is added to ice water and 2N hydrochloric acid is added until acidic. The mixture is extracted several times with MTBE and the combined organic phases are washed with sat. Washed sodium chloride solution. The solution is dried with sodium sulfate and fully concentrated. The residue is purified by column chromatography (SiO ₂ , n-heptane -7 toluene). Further purification is carried out by recrystallization from n-heptane. 4,5-Difluoro-7-propyl-2-(4-propyl-phenyl)-6,7,8,9-tetrahydro-naphtho[2,1-b]furan is obtained as a colorless solid with a melting point of 72° received C.

Δε = -5.6
Δn = 0.1958
γ ₁ = 466 mPa.s
Tg -24K 72 N(56) I

¹ H NMR (300 MHz, CHCl ₃ ): δ = 7.72 (d, 2H, J = 8.2 Hz, _Harom .), 7.23 (d, 2H, J = 8.2 Hz, H _arom .), 6.83 (d, 1H, J=3.0 Hz, 1-H), 2.98-2.87 (m, 2H, H _aliph ), 2.82-2.70 (m, 1H, H _aliph ), 2.61 (t, 2H, J = 7.7 Hz, H _aliph. ), 2.23 (dd, 1H, J = 10.1 Hz, J = 16.7 Hz, H _{aliph .} ), 2.03-1.93 (m, 1H, H _aliph. ), 1.75-1.60 (m, 3H, H _aliph. ), 1.49-1.32 (m, 5H, H _aliph. ), 0.98-0.92 (m, 6H, H _aliph. ).

¹⁹ F NMR (282 MHz, CHCl ₃ ): δ = -148.3 (d, 1F, J=20.6 Hz), -165.6 (d, 1F, J=20.6 Hz).

MS (EI): m/z(%) = 368 (100, M ⁺ ), 339 (38, [M - CH ₂ CH ₃ ] ⁺ ).

Example 2: 4,5-Difluoro-2-propyl-7-(4-propylcyclohexyl)-6,7,8,9-tetrahydronaphtho[2,1-b]furan

2.1 Preparation of trifluoromethanesulfonic acid 7,8-difluoro-3,4-dihydronaphthalen-2-yl ester

54.0 g (1.35 mol) of sodium hydride (60% suspension in paraffin oil) are washed with pentane and suspended in 1.25 l of diethyl ether. A solution of 120.0 g (0.66 mol) of 7,8-difluoro-3,4-dihydro-1H-naphthalen-2-one in 750 ml of diethyl ether is slowly metered into the suspension, and the mixture is removed after the addition is complete stirred at RT for 30 min. The mixture is cooled to 0°C and 120.0 mL (0.71 mol) of trifluoroacetic anhydride is added dropwise. After the addition is complete, the mixture is stirred at 0° C. for 2 h and added to dilute hydrochloric acid. The mixture is extracted several times with MTBE and the combined organic phases are washed with sat. sodium chloride solution washed. The solution is filtered absorptively (SiO ₂ , MTBE) and the filtrate is completely concentrated. The residue is treated with n-heptane: toluene = 7:3 and the organic phase is separated. The solution is fully concentrated and the residue is purified by column chromatography (SiO ₂ , n-heptane: toluene=7:3). Trifluoromethanesulfonic acid 7,8-difluoro-3,4-dihydronaphthalen-2-yl ester is obtained as a yellow oil.

2.2 Preparation of 5,6-difluoro-3-(4-propylcyclohexyl)-1,2-dihydronaphthalene

9.0 g (28.6 mmol) of trifluoromethanesulfonic acid 7,8-difluoro-3,4-dihydronaphthalen-2-yl ester are dissolved together with 550 mg (1.55 mmol) of Fe(acac) ₃ and 30 mL of NMP in 500 mL THF submitted at -30 °C. A solution of 4-propylcyclohexylmagnesium bromide produced from 30.0 g (0.15 mol) of 4-bromopropylcyclohexane and 3.6 g (0.15 mol) of magnesium turnings in 350 ml of diethyl ether is metered in rapidly. After the addition is complete, the mixture is stirred at -30° C. for 30 min and saturated. ammonium chloride solution given. The mixture is extracted several times with MTBE and the combined organic phases are washed with sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The residue is purified by column chromatography (SiO ₂ , n-heptane). 5,6-Difluoro-3-(4-propylcyclohexyl)-1,2-dihydronaphthalene is obtained as a colorless oil.

2.3 Preparation of 7,8-difluoro-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene

76.0 g (0.26 mol) of 5,6-difluoro-3-(4-propylcyclohexyl)-1,2-dihydronaphthalene are dissolved in 500 ml of THF at RT and atmospheric pressure in the presence of Pd-C (5% Pd ) hydrogenated for 19 h. The reaction solution is filtered and fully concentrated. The residue is used for the following reaction without further purification.

2.4 Preparation of 3,4-difluoro-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol

77.0 g (approx. 0.26 mol) of crude 7,8-difluoro-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene are placed in 500 ml of THF and at -70.degree mixed with 200.0 ml (0.32 mol) n-BuLi (15% solution in hexane). After 3 hours at this temperature, 37.0 ml (0.33 mol) of trimethyl borate are added dropwise, the batch is warmed to 0° C. and 80 ml of dilute acetic acid (about 30%) are added. The mixture is warmed to 30°C and 70 mL of hydrogen peroxide solution (35%) is carefully added. After the addition is complete, the mixture is stirred at RT for 2 h. Water is added and the mixture is acidified with dilute hydrochloric acid. The solution is extracted several times with MTBE and the combined organic phases are washed successively with water, sat. sodium chloride solution and ammonium iron (II) sulfate solution. washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). Further purification is carried out by crystallization from n-heptane. 3,4-Difluoro-6-(4-propyl-cyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol is obtained as a colorless solid.

2.5 Preparation of 7,8-difluoro-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene

37.4 g (0.12 mol) of 3,4-difluoro-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol are dissolved in 300 ml of dichloromethane and 24.5 ml (0.15 mmol) of N-ethyldiisopropylamine is added under ice-cooling. After 5 minutes, 11.0 ml (0.15 mol) of chloromethyl methyl ether are metered in at a temperature of from 3 to 8.degree. After 17 h at RT, 50 ml of triethylamine are added and the mixture is stirred for 30 min. Water is added to the reaction mixture and the organic phase is separated off. The aqueous phase is extracted with dichloromethane and the combined organic phases are washed successively with water and sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). There is thus obtained 7,8-difluoro-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene as a colorless oil.

2.6 Preparation of 7,8-difluoro-5-iodo-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene

35.5 g (0.10 mol) of 7,8-difluoro-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene are placed in 250 ml of THF and at - 75 ° C treated dropwise with 75.0 ml (0.12 mol) n-BuLi (15% solution in hexane). After the addition is complete, the mixture is stirred at this temperature for 30 min and then at 0° C. for 1 h. The solution is again cooled to -75°C and a solution of 30.4 g (0.12 mol) of iodine in 150 ml of THF is added dropwise. The reaction mixture is stirred at -78° C. for 30 min and at 0° C. for 1 h. The batch is diluted with MTBE and the solution is made half-conc. sodium hydrogen sulfite solution shifted. The mixture is washed with water and with sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , n-heptane: toluene=7:3). Further purification is carried out by crystallization from IPA. 7,8-Difluoro-5-iodo-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene is obtained as a colorless solid.

2.7 Preparation of 7,8-Difluoro-6-methoxymethoxy-5-pent-1-ynyl-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene

5.8 g (12.1 mmol) of 7,8-difluoro-5-iodo-6-methoxymethoxy-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene are added together with 2.0 ml (20 .3 mmol) 1-pentyne in the presence of 281 mg (0.40 mmol) bis(triphenylphosphine)palladium(II) chloride and 40 mg (0.2 mmol) copper(I) iodide in 50 ml triethylamine 2 d stirred at RT and at 45° C. for 3 h. The mixture is added to ice water and 2N hydrochloric acid is added until acidic. The mixture is extracted several times with MTBE and the combined organic phases are washed with sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The residue is purified by column chromatography (SiO ₂ , n-heptane: toluene=1:1). 7,8-Difluoro-6-methoxymethoxy-5-pent-1-ynyl-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene is obtained as an orange oil.

2.8 Preparation of 3,4-difluoro-1-pent-1-ynyl-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol

A solution of 2.8 g (6.69 mmol) of 7,8-difluoro-6-methoxymethoxy-5-pent-1-ynyl-2-(4-propylcyclohexyl)-1,2,3,4-tetrahydronaphthalene in 20 ml THF with 1.2 ml conc. HCl is added, and the mixture is stirred at RT for 18 h. The batch is diluted with MTBE and the solution is washed with water. The aqueous phase is extracted with MTBE and the combined organic phases are washed with water and sat. sodium chloride solution washed. The solution is dried with sodium sulfate and fully concentrated. The crude product is purified by column chromatography (SiO ₂ , toluene). There is thus obtained 3,4-difluoro-1-pent-1-ynyl-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydro-naphthalen-2-ol as a pale orange solid.

2.9 Preparation of 4,5-difluoro-2-propyl-7-(4-propylcyclohexyl)-6,7,8,9-tetrahydronaphtho[2,1-b]furan

Δε = -5,5
Δn = 0,0934
γ1 = 662 mPa·s
K 68 N (50) I1.90 g (5.07 mmol) of 3,4-difluoro-1-pent-1-ynyl-6-(4-propylcyclohexyl)-5,6,7,8-tetrahydronaphthalen-2-ol are added together with 80 μl (0.54 mmol) TMEDA are introduced and the mixture is treated at 3° C. with 2.8 ml (2.8 mmol) diethylzinc (1 M solution in heptane). After the evolution of gas has subsided, 10 ml of toluene are added and the mixture is refluxed for 20 h. The solution becomes sat. ammonium chloride solution added and the mixture is extracted with toluene. The combined organic phases are washed with water and sat. sodium chloride solution washed and dried with sodium sulfate. The solution is completely concentrated and the residue is purified by column chromatography (SiO ₂ , n-heptane: toluene=1:1). Further purification is carried out by repeated recrystallization from IPA at a reduced temperature. 4,5-Difluoro-2-propyl-7-(4-propylcyclohexyl)-6,7,8,9-tetrahydronaphtho[2,1-b]furan is obtained as a colorless solid with a melting point of 68°C.

Δε = -5.5
Δn = 0.0934
γ1 = 662 mPas
K 68 N (50) I

¹ H NMR (300 MHz, CHCl ₃ ): δ = 6.30 (d, 1H, J = 0.6 Hz, 1-H), 2.94-2.85 (m, 2H, H _aliph. ) , 2.76-2.64 (m, 3H, H _aliph. ), 2.23 (dd, 1H, J = 10.5 Hz, J = 16.5 Hz, H _aliph. ), 2.03-1 .95 (m, 1H, H _aliph. ), 1.88-1.70 (m, 6H, H _aliph. ), 1.55-0.83 (m, 18H).

¹⁹ F NMR (282 MHz, CHCl ₃ ): δ = -150.1 (d, 1F, J=20.6 Hz), -166.1 (d, 1F, J=20.6 Hz).

MS (EI): m/z(%) = 374 (100, M ⁺ ).

Claims (5)

Compounds of formula I:

wherein m and n are each independently 0 or 1, where m + n is 0 or 1; L ¹ and L ² are each independently F; Y ¹ is -Y ² >C=CH-; A ¹ and A ² are each (a) independently 1,4-phenylene, or (b) 1,4-cyclohexylene; Z ¹ and Z ² are each independently a single bond; R ¹ and R ² , independently of one another, are an unsubstituted alkanyl radical having 1 to 7 carbon atoms; and Ring B

connections after claim 1 , characterized in that m and n are both zero. connections after claim 1 , characterized in that m + n = 1 and A ¹ or A ² independently

mean. Use of one or more compounds according to one or more of Claims 1 until 3 in liquid crystalline media. Liquid-crystalline medium containing at least two compounds, characterized in that it contains at least one compound according to one or more of Claims 1 until 3 contains.