Fluorinated dibenzofuran and dibenzothiophene derivatives

Abstract

Disclosed are dibenzofuran and dibenzothiophene derivatives of the general formula I, ##STR00001##
in which X.sup.1, X.sup.2, W, Y, R, A, Z and m have the meaning defined in claim 1, to a process for the preparation thereof, to the use thereof as components in liquid-crystalline media, and to electro-optical display elements which contain the liquid-crystalline media according to the invention.

Claims

1. A compound of the formula I ##STR00038## in which W denotes O or S, Y denotes F, Cl, CF.sub.3, OCF.sub.3 or OCF.sub.2H, with the proviso that, if W denotes O, Y cannot be F, X.sup.1, X.sup.2 denote H or F, with the proviso that at least one radical X.sup.1 or X.sup.2 denotes F, R denotes an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH.sub.2 groups in these radicals may each be replaced, independently of one another, by CC, CF.sub.2O, OCF.sub.2, CHCH, ##STR00039## O, COO or OCO in such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen, A on each occurrence, identically or differently, denotes a radical selected from the following groups: a) 1,4-phenylene, in which, in addition, one or two CH groups may be replaced by N and in which, in addition, one or more H atoms may be replaced by a group L, b) the group consisting of trans-1,4-cyclohexylene and 1,4-cyclohexenylene, in which, in addition, one or more non-adjacent CH.sub.2 groups may be replaced by O and/or S and in which, in addition, one or more H atoms may be replaced by F or Cl, and c) the group consisting of tetrahydropyran-2,5-diyl, 1,3-dioxane-2,5-diyl, tetrahydrofuran-2,5-diyl, cyclobutane-1,3-diyl, piperidine-1,4-diyl, thiophene-2,5-diyl and selenophene-2,5-diyl, each of which may also be mono- or polysubstituted by a group L, L on each occurrence, identically or differently, denotes F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, and in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms, and Z on each occurrence, identically or differently, denotes a single bond, CF.sub.2O, OCF.sub.2, CH.sub.2O, OCH.sub.2, (CO)O, O(CO), (CH.sub.2).sub.4, CH.sub.2CH.sub.2, CF.sub.2CF.sub.2, CF.sub.2CH.sub.2, CH.sub.2CF.sub.2, CHCH, CFCF, CFCH, CHCF, (CH.sub.2).sub.3O, O(CH.sub.2).sub.3, CC, O, CH.sub.2, (CH.sub.2).sub.3 or CF.sub.2, m denotes 0, 1 or 2.

2. A compound according to claim 1, wherein X.sup.1 and X.sup.2 both denote F.

3. A compound according to claim 1, wherein m denotes 0 or 1.

4. A compound according to claim 1, wherein Y in formula I denotes CF.sub.3 or OCF.sub.3.

5. A compound according to claim 4, wherein Y denotes OCF.sub.3.

6. A compound according to claim 1, wherein the compound of the formula I is selected from the compounds of sub-formulae Ia to Id, ##STR00040## in which R, A, Z and Y have the meanings indicated for formula I in claim 1.

7. A compound according to claim 1, wherein W denotes O.

8. A compound according to claim 1, wherein the compound is selected from the compounds of the following formulae: ##STR00041## ##STR00042##

9. Liquid-crystalline medium comprising at least two compounds, which comprises at least one compound according to claim 1.

10. Electro-optical display element containing a liquid-crystalline medium according to claim 9.

11. Process for the preparation of a compound of the formula I according to claim 1, comprising converting a compound of the formula II into a compound of the formula I ##STR00043## where R, A, Z, X.sup.1, X.sup.2, W, Y and m have the meaning indicated under claim 1 and G denotes OH or SG, where G denotes H or a protecting group.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Exemplary embodiments of the present invention are described in detail below.

(2) R preferably denotes an alkoxy radical, alkyl radical or alkenyl radical having 1 to 7 or 2 to 7 carbon atoms respectively. R in the general formula I is particularly preferably an alkoxy radical or alkyl radical having 2 to 7 C atoms. In the case where m=0, R preferably denotes an alkoxy group having 1-7 C atoms, particularly preferably having 2 to 5 C atoms.

(3) In the case where m=1 or 2, R preferably denotes an alkyl, alkoxy or alkenyl group, particularly preferably an alkyl or alkenyl group having 1-7 C atoms, particularly preferably having 2 to 5 C atoms.

(4) If R represents an alkyl radical, this is straight-chain or branched. R is preferably straight-chain and, unless indicated otherwise, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is accordingly preferably methyl, ethyl, propyl, butyl, pentyl, hexyl or heptyl.

(5) If R represents an alkoxy radical, this is straight-chain or branched. R is preferably straight-chain and, unless indicated otherwise, has 1, 2, 3, 4, 5, 6 or 7 C atoms and is accordingly preferably methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy or heptoxy.

(6) R in formula I can furthermore be an alkenyl radical having 2 to 15 C atoms, which is straight-chain or branched and contains at least one CC double bond. It is preferably straight-chain and has 2 to 7 C atoms. It is accordingly preferably vinyl, prop-1- or -2-enyl, but-1-, -2- or -3-enyl, pent-1-, -2-, -3- or -4-enyl, hex-1-, -2-, -3-, -4- or -5-enyl, hept-1-, -2-, -3-, -4-, -5- or -6-enyl. If both C atoms of the CC double bond are substituted, the alkenyl radical can be in the form of the E and/or Z isomer (trans/cis). In general, the respective E isomers are preferred. Of the alkenyl radicals, prop-2-enyl, but-2- or -3-enyl and pent-3- or -4-enyl are particularly preferred.

(7) R in formula I can also be an alkynyl radical having 2 to 15 C atoms, which is straight-chain or branched and contains at least one CC triple bond. 1- or 2-propynyl and 1-, 2- or 3-propynyl are preferred.

(8) The group A on each occurrence, identically or differently, preferably denotes a disubstituted cyclic group selected from the formulae

(9) ##STR00008##
in particular

(10) ##STR00009##

(11) The group Z preferably denotes a single bond, CH.sub.2O, CF.sub.2O or OCF.sub.2, particularly preferably CH.sub.2O.

(12) The group W preferably denotes O.

(13) For the groups X.sup.1 and X.sup.2, it is preferred for both to denote F.

(14) The group Y preferably denotes CF.sub.3 or OCF.sub.3, particularly preferably OCF.sub.3.

(15) The group L preferably denotes F, Cl, CF.sub.3 or an alkyl or alkoxy group having 1, 2 or 3 carbon atoms, particularly preferably F.

(16) The parameter m preferably has a value of 0 or 1.

(17) Particularly preferably, m denotes 0 and R denotes an alkoxy group having 1 to 7 carbon atoms.

(18) Halogen in the context of the present invention denotes fluorine, chlorine, bromine or iodine, in particular fluorine or chlorine.

(19) In connection with the present invention, the expression alkylif not defined otherwise elsewhere in this description or in the claimsdenotes a straight-chain or branched, saturated, aliphatic hydrocarbon radical having 1 to 15 carbon atoms.

(20) Particular preference is given to compounds of the formula I according to the invention selected from the sub-formulae Ia to Id,

(21) ##STR00010##
where the radicals R, A, Z and Y have the meanings indicated above.

(22) Preferred compounds of the formulae Ia, Ib, Ic and Id are the compounds of the formulae Ia and Ib having the preferred sub-formulae Ia-1 and Ia-2,

(23) ##STR00011##
in which R denotes a straight-chain alkoxy group having 1 to 5 C atoms,
and Ib-1 and Ib-2,

(24) ##STR00012##
in which R denotes a straight-chain alkyl or alkenyl group having 2 to 5 C atoms.

(25) Very particular preference is given to compounds of the formulae Ia-1-1 to Ia-1-8 and Ib-1-1 to Ib-1-5,

(26) ##STR00013## ##STR00014##

(27) If radicals or substituents of the compounds according to the invention or the compounds according to the invention themselves are in the form of optically active or stereoisomeric radicals, substituents or compounds respectively since they have, for example, a centre of asymmetry, these are likewise encompassed by the present invention. In this case, the compounds of the general formula I according to the invention may exist in isomerically pure form, for example as pure enantiomers, diastereomers, E or Z isomers, trans or cis isomers, or as a mixture of a plurality of isomers in any desired ratio, for example as a racemate, E/Z isomer mixture or as a cis/trans isomer mixture.

(28) The 1,4-substituted cyclohexyl ring of the formula

(29) ##STR00015##
or -Cyc- in the compounds disclosed for liquid-crystalline media preferably has the trans configuration, i.e. the two substituents are both in the equatorial position in the thermodynamically preferred chair conformation.

(30) The compounds of the general formula I can be prepared by methods known per se, as described in the literature (for example in the standard works, such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart), to be precise under reaction conditions which are known and suitable for the said reactions. Use can be made here of variants known per se which are not mentioned here in greater detail.

(31) If desired, the starting materials can also be formed in situ by not isolating them from the reaction mixture, but instead immediately converting them further into the compounds of the general formula I.

(32) The syntheses of 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 by generally accessible literature procedures or are commercially available.

(33) Particularly suitable synthetic routes to the compounds according to the invention are explained below with reference to Scheme 1.

(34) ##STR00016##

(35) Scheme 1 should only be regarded as illustrative. The person skilled in the art will be able to carry out corresponding variations of the syntheses presented, and also follow other suitable synthetic routes, in order to obtain compounds of the formula I.

(36) In accordance with the synthesis depicted above, the present invention in an embodiment also encompasses one or more processes for the preparation of compounds of the formula I.

(37) The invention thus encompasses a process for the preparation of compounds of the formula I which is characterised in that it comprises a process step in which a compound of the formula II is converted into compounds of the formula I in the presence of a base, as shown in Scheme 2 and in which R, A, Z, X.sup.1, X.sup.2, W and m have the meaning indicated above and G denotes OH, SH or SG and G denotes a base-labile protecting group for thiols. Preferred protecting groups are acetyl, dimethylaminocarbonyl, 2-tetrahydropyranyl, ethoxycarbonylethyl, tertbutyl, methyl, particularly preferably ethoxycarbonylethyl.

(38) ##STR00017##

(39) The process and the subsequent work-up of the reaction mixture can basically be carried out as a batch reaction or in a continuous reaction procedure. The continuous reaction procedure encompasses, for example, reaction in a continuous stirred-tank reactor, a stirred-reactor cascade, a loop or cross-flow reactor, a flow tube or in a microreactor. The reaction mixtures are optionally worked up, as necessary, by filtration via solid phases, chromatography, separation between immiscible phases (for example extraction), adsorption onto solid supports, removal of solvents and/or azeotropic mixtures by distillation, selective distillation, sublimation, crystallisation, co-crystallisation or by nanofiltration on membranes.

(40) As already mentioned, the compounds of the general formula I can be used in liquid-crystalline media. The present invention therefore also relates to a liquid-crystalline medium comprising at least two liquid-crystalline compounds, comprising at least one compound of the general formula I.

(41) The present invention also relates to liquid-crystalline media comprising 2 to 40, preferably 4 to 30, components as further constituents besides one or more compounds of the formula I according to the invention. These media particularly preferably comprise 7 to 25 components besides one or more compounds according to the invention. These further constituents are preferably selected from nematic or nematogenic (monotropic or isotropic) substances, in particular substances from the classes of the azoxybenzenes, benzylideneanilines, biphenyls, terphenyls, 1,3-dioxanes, 2,5-tetrahydropyrans, phenyl or cyclohexyl benzoates, phenyl or cyclohexyl esters of cyclohexanecarboxylic acid, phenyl or cyclohexyl esters of cyclohexylbenzoic acid, phenyl or cyclohexyl esters of cyclohexylcyclohexanecarboxylic acid, cyclohexylphenyl esters of benzoic acid, of cyclohexanecarboxylic acid or of cyclohexylcyclohexanecarboxylic acid, phenylcyclohexanes, cyclohexylbiphenyls, phenylcyclohexylcyclohexanes, cyclohexylcyclohexanes, cyclohexylcyclohexylcyclohexenes, 1,4-biscyclohexylbenzenes, 4,4-biscyclohexylbiphenyls, phenyl- or 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, benzyl phenyl ethers, tolans and substituted cinnamic acids. The 1,4-phenylene groups in these compounds may also be mono- or polyfluorinated.

(42) The most important compounds suitable as further constituents of media according to the invention can be characterised by the formulae (II), (III), (IV), (V) and (VI):
R-L-E-R(II)
R-L-COO-E-R(III)
R-L-OOC-E-R(IV)
R-L-CH.sub.2CH.sub.2-E-R(V)
R-L-CF.sub.2O-E-R(VI)

(43) In the formulae (II), (III), (IV), (V) and (VI), L and E, which may be identical or different, each, independently of one another, denote a divalent radical from the group formed by -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -Thp-, -G-Phe- and -G-Cyc- and their mirror images, where Phe denotes unsubstituted or fluorine-substituted 1,4-phenylene, Cyc denotes trans-1,4-cyclohexylene or 1,4-cyclohexenylene, Pyr denotes pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio denotes 1,3-dioxane-2,5-diyl, Thp denotes tetrahydropyran-2,5-diyl and G denotes 2-(trans-1,4-cyclo-hexyl)ethyl, pyrimidine-2,5-diyl, pyridine-2,5-diyl, 1,3-dioxane-2,5-diyl or tetrahydropyran-2,5-diyl.

(44) One of the radicals L and E is preferably Cyc or Phe. E is preferably Cyc, Phe or Phe-Cyc. The media according to the invention preferably comprise one or more components selected from the compounds of the formulae (II), (III), (IV), (V) and (VI) in which L and E are selected from the group consisting of Cyc and Phe and simultaneously one or more components selected from the compounds of the formulae (II), (III), (IV), (V) and (VI) in which one of the radicals L and E is selected from the group consisting of Cyc and Phe and the other radical is selected from the group consisting of -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-, and optionally one or more components selected from the compounds of the formulae (II), (III), (IV), (V) and (VI) in which the radicals L and E are selected from the group consisting of -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-.

(45) In a smaller sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), R and R each, independently of one another, denote alkyl, alkenyl, alkoxy, alkoxyalkyl (oxaalkyl), alkenyloxy or alkanoyloxy having up to 8 C atoms. This smaller sub-group is called group A below, and the compounds are referred to by the sub-formulae (IIa), (IIIa), (IVa), (Va) and (VIa). In most of these compounds, R and R are different from one another, one of these radicals usually being alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

(46) In another relatively small sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), known as group B, R denotes F, Cl, NCS or (O).sub.iCH.sub.3-kF.sub.k, where i is 0 or 1 and k is 1, 2 or 3. The compounds in which R has this meaning are denoted by the sub-formulae (IIb), (IIIb), (IVb), (Vb) and (VIb). Particular preference is given to compounds of the sub-formulae (IIb), (IIIb), (IVb), (Vb) and (VIb) in which R has the meaning F, Cl, NCS, CF.sub.3, OCHF.sub.2 or OCF.sub.3.

(47) In the compounds of group B, which are referred to by the sub-formulae (IIb), (IIIb), (IVb), (Vb) and (VIb), R is as defined for the compounds of the sub-formulae (IIa) to (VIa) and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

(48) In a further smaller sub-group of the compounds of the formulae (II), (III), (IV), (V) and (VI), R denotes CN. This sub-group is referred to below as group C, and the compounds of this sub-group are correspondingly described by sub-formulae (IIc), (IIIc), (IVc), (Vc) and (VIc). In the compounds of the sub-formulae (IIc), (IIIc), (IVc), (Vc) and (VIc), R is as defined for the compounds of the sub-formulae (IIa) to (VIa) and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl (oxaalkyl).

(49) Besides the preferred compounds of groups A, B and C, other compounds of the formulae (II), (III), (IV), (V) and (VI) having other variants of the proposed substituents are also customary. All these substances are obtainable by methods which are known from the literature or analogously thereto.

(50) Besides the compounds of the general formula I according to the invention, the media according to the invention preferably comprise one or more compounds from groups A, B and/or C. The proportions by weight of the compounds from these groups in the media according to the invention are:

(51) Group A:

(52) from 0 to 90%, preferably from 20 to 90%, in particular from 30 to 90%.

(53) Group B:

(54) from 0 to 80%, preferably from 10 to 80%, in particular from 10 to 70%.

(55) Group C:

(56) from 0 to 80%, preferably from 5 to 80%, in particular from 5 to 50%.

(57) The media according to the invention preferably comprise from 1 to 40%, particularly preferably from 5 to 30%, by weight of the compounds of the formula I according to the invention, based on the total weight of the composition. The media preferably comprise one, two, three, four or five compounds of the formula I according to the invention.

(58) The media according to the invention are prepared in a manner conventional per se. In general, the components are dissolved in one another, preferably at elevated temperature. By means of suitable additives, the liquid-crystalline phases of the present invention can be modified in such a way that they can be used in all types of liquid-crystal display element that have been disclosed hitherto. Additives of this type are known to the person skilled in the art and are described in detail in the literature (H. Kelker/R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980). For example, pleochroic dyes can be added for the production of coloured guest-host systems or substances can be added in order to modify the dielectric anisotropy, the viscosity and/or the alignment of the nematic phases.

(59) Owing to their negative , the compounds of the formula I are suitable for use in VA-TFT displays.

(60) The value for of compounds of formula I is preferably in the range from 10 to 50, more preferably in the range from 15-40 and particularly preferably in the range from 18 to 30. Owing to their high value for , the compounds of the formula I are particularly suitable for use in FFS-TFT displays.

(61) The present invention therefore also relates to electro-optical liquid-crystal display elements containing a liquid-crystalline medium according to the invention.

(62) Further combinations of the embodiments and variants of the invention in accordance with the description arise from the claims.

(63) The invention is explained in greater detail below with reference to working examples, but without intending to be restricted thereby. The person skilled in the art will be able to glean from the examples working details that are not given in detail in the general description, generalise them in accordance with general expert knowledge and apply them to a specific problem.

(64) Besides the usual and well-known abbreviations, the following abbreviations are used:

(65) C: crystalline phase; N: nematic phase; Sm: smectic phase; I: isotropic phase. The numbers between these symbols show the transition temperatures of the substance concerned.

(66) Temperature data are in C., unless indicated otherwise.

(67) Physical, physicochemical or electro-optical parameters are determined by generally known methods, as described, inter alia, in the brochure Merck Liquid CrystalsLicristalPhysical Properties of Liquid CrystalsDescription of the Measurement Methods, 1998, Merck KGaA, Darmstadt.

(68) Above and below, n denotes the optical anisotropy (589 nm, 20 C.) and denotes the dielectric anisotropy (1 kHz, 20 C.). The dielectric anisotropy is determined at 20 C. and 1 kHz. The optical anisotropy n is determined at 20 C. and a wavelength of 589.3 nm.

(69) The and n values and the rotational viscosity (.sub.1) of the compounds according to the invention are obtained by linear extrapolation from liquid-crystalline mixtures consisting of 5 to 10% of the respective compound according to the invention and 90-95% of the commercially available liquid-crystal mixture ZLI-2857 (for ) or ZLI-4792 (for n, .sub.1) (mixtures, Merck KGaA, Darmstadt).

(70) The abbreviations above and below have the following meanings:

(71) DMAP 4-(N,N-dimethylamino)pyridine

(72) DMPU 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone

(73) dpephos bis[2-(diphenylphosphino)phenyl] ether

(74) dba dibenzylideneacetone

(75) n-BuLi n-butyllithium, solution in hexane

(76) MTB ether methyl tert-butyl ether

(77) THF tetrahydrofuran

EXAMPLES

(78) The present invention is described in detail by the following non-restrictive examples.

Example 1: 4,6-Difluoro-3-trifluoromethoxy-7-pentyloxydibenzofuran

1.1: 1,2-Difluoro-3-pentyloxybenzene

(79) ##STR00018##

(80) 19.0 g (146 mmol) of 2,3-difluorophenol and 20.1 ml (163 mmol) of 1-bromopentane are dissolved in ethyl methyl ketone, 22.4 g of potassium carbonate are added, and the mixture is heated at the boil overnight. The solid is subsequently separated off, and the solvent is removed. The pentyl 2,3-difluorophenyl ether obtained is employed in the subsequent step without further purification.

1.2: 2,3-Difluoro-4-pentyloxybenzeneboronic acid

(81) ##STR00019##

(82) 108 ml of a 15% solution of n-butyllithium in n-hexane (172 mmol) are added to a solution of 31.2 g of the crude product from step 1 (10) in 225 ml of THF at 70 C. After 1 h at this temperature, 20 ml (176 mmol) of trimethyl borate dissolved in 25 ml of THF are added. After a further hour, the batch is warmed to 0 C., water is added, and the mixture is adjusted to pH 1 using 25% hydrochloric acid. The aqueous phase is separated off and extracted with MTB ether. The combined organic phases are dried over sodium sulfate and evaporated. Crystallisation from n-heptane gives 2,3-difluoro-4-pentyloxybenzeneboronic acid as a colourless solid.

1.3: 6-Bromo-2-fluoro-3-trifluoromethoxyphenol

(83) ##STR00020##

(84) 227 mmol of an LDA solution in 100 ml of THF, prepared from 32 ml of diisopropylamine and 143 ml of a 15% solution of n-butyllithium in n-hexane, are added to a solution of 33 ml (207 mmol) of 1-bromo-3-fluoro-4-trifluoromethoxybenzene (12) in 150 ml of THF at a temperature of 70 C. under nitrogen. After 1 h at the temperature, 26 ml (104 mmol) of trimethyl borate, dissolved in 50 ml of THF, are added to the batch. After a further hour, the batch is warmed to 0 C., and 30 ml of glacial acetic acid diluted with 38 ml of water are added. After 30 min. at room temp., 45 ml of a 35 percent hydrogen peroxide solution are added dropwise at a temperature between 35 C. and 40 C. After completion of the addition, the batch is kept at between 35 C. and 40 C. for 3 h, subsequently cooled to room temp., and water and MTB ether are added. The organic phase is washed with water and ammonium iron(II) sulfate solution, dried over sodium sulfate and evaporated. The residue is filtered through silica gel with n-pentane/dichloromethane, giving 6-bromo-2-fluoro-3-trifluoro-methoxyphenol as colourless oil.

1.4: 3,2,3-Trifluoro-4-pentyloxy-4-trifluoromethoxybiphenyl-2-ol

(85) ##STR00021##

(86) 1.8 g (13 mmol) of potassium carbonate, 6 ml of water and, at about 60 C., 40 mg (4 mmol) of tris(dibenzylideneacetone)dipalladium(0) and 50 mg of di-(1-adamantyl)butylphosphine are added to a solution of 3 g (80%, 9 mmol) of 6-bromo-2-fluoro-3-trifluoromethoxyphenol (13) in 15 ml of THF under nitrogen, and the mixture is subsequently heated to the boil. A solution of 2.6 g (97%, 10 mmol) of 2,3-difluoro-4-pentyloxybenzeneboronic acid (11) in 10 ml of THF is added dropwise at the boiling point. The batch is heated under reflux overnight and cooled, water and MTB ether are added, and the mixture is acidified using dil. hydrochloric acid. The aqueous phase is extracted with MTB ether. The combined organic phases are dried over sodium sulfate and evaporated, and the residue is filtered through silica gel with toluene, giving 3,2,3-trifluoro-4-pentyloxy-4-trifluoromethoxybiphenyl-2-ol as colourless solid.

1.5: 4,6-Difluoro-3-trifluoromethoxy-7-pentyloxydibenzofuran

(87) ##STR00022##

(88) 2.40 g (5.56 mmol) of 3,2,3-trifluoro-4-pentyloxy-4-trifluoromethoxy-biphenyl-2-ol and 15.5 g (6.60 mmol) of potassium triphosphate monohydrate are left to stir overnight at 110 C. in 20 ml of DMPU. After cooling, the batch is diluted with MTB ether, washed with water and sat. sodium chloride solution and dried over sodium sulfate. The crude product is chromatographed on silica gel with toluene and recrystallised from toluene, giving 4,6-difluoro-3-trifluoromethoxy-7-pentyloxydibenzofuran as colourless crystals of m.p. 68 C.

(89) The following compounds are prepared analogously to Example 1:

(90) TABLE-US-00001 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 1 n-C.sub.5H.sub.11 68 19.81 3.55 0.1361 68 2 CH.sub.3 112 3 C.sub.2H.sub.5 112 4 n-C.sub.3H.sub.7 97 5 n-C.sub.4H.sub.9 87 6 n-C.sub.6H.sub.13 72 20.84 5.40 0.1393 100

(91) The compound

(92) ##STR00024##
known from the prior art has the following values:

(93) =7.79

(94) .sub.=24.69

(95) .sub./||=3.17

(96) For Example 1, .sub./||=5.58 is obtained.

(97) For Example 6, .sub./||=3.86 is obtained.

(98) The comparison shows that the compounds according to the invention have much higher and thus more advantageous values for the ratio of .sub. to ||.

(99) The following compounds are prepared analogously to Example 1:

(100) TABLE-US-00002 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 7 CH.sub.3 8 C.sub.2H.sub.5 9 n-C.sub.3H.sub.7 10 n-C.sub.4H.sub.9 11 n-C.sub.5H.sub.11 46 16.29 3.16 0.1113 59 12 n-C.sub.6H.sub.13

(101) The following compounds are prepared analogously to Example 1:

(102) TABLE-US-00003 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 13 CH.sub.3 14 C.sub.2H.sub.5 15 n-C.sub.3H.sub.7 16 n-C.sub.4H.sub.9 17 n-C.sub.5H.sub.11 74 23.66 2.99 0.1333 85 18 n-C.sub.6H.sub.13 76 23.11 3.76 0.1333 89

(103) The following compounds are prepared analogously to Example 1:

(104) TABLE-US-00004 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 19 CH.sub.3 20 C.sub.2H.sub.5 21 n-C.sub.3H.sub.7 22 n-C.sub.4H.sub.9 23 n-C.sub.5H.sub.11 46 18.84 2.17 0.1212 75 24 n-C.sub.6H.sub.13

Example 25: Butoxy-4,6-difluoro-7-trifluoromethoxydibenzothiophene

25.1: 3,2,3-Trifluoro-4-butyloxy-4-trifluoromethoxybiphenyl-2-ol

(105) ##STR00028##

(106) Phenol 22 is prepared analogously to compound 14 by a Suzuki coupling from compound 13 and commercially available 4-butoxy-2,3-difluoro-benzeneboronic acid.

25.2: 3,2,3-Trifluoro-4-butyloxy-4-trifluoromethoxybiphenyl-2-yl trifluoro-methanesulfonate

(107) ##STR00029##

(108) Triethylamine (5.0 ml) and DMAP (60 mg) are added dropwise to a solution of 3,2,3-trifluoro-4-butyloxy-4-trifluoromethoxybiphenyl-2-ol (9.7 g) in dichloromethane (70 ml). Trifluoromethanesulfonic anhydride (5.0 ml) is subsequently added dropwise at 5 C., and the reaction mixture is stirred at room temperature for 20 h. The mixture is filtered through silica gel, washed with dichloromethane, dried (Na.sub.2SO.sub.4) and evaporated in vacuo. 3,2,3-Trifluoro-4-butyloxy-4-trifluoromethoxybiphenyl-2-yl trifluoro-methanesulfonate 9 is isolated as residue in the form of a pale-yellow oil.

25.3: Ethyl 3-(4-butoxy-3,2,3-trifluoro-4-trifluoromethoxybiphenyl-2-yl-sulfanyl)propionate

(109) ##STR00030##

(110) A solution of 3,2,3-trifluoro-4-butyloxy-4-trifluoromethoxybiphenyl-2-yl trifluoromethanesulfonate (12.7 g) and ethyl 3-mercaptopropionate (3.8 ml) in toluene (55 ml) is heated under reflux under a nitrogen atmosphere, and bis(2-diphenylphosphinophenyl) ether (1.3 g), tris(dibenzylidene-acetone)dipalladium(0) (1.2 g), potassium carbonate (8.4 g) and a small amount of dried molecular sieve are added. The reaction mixture is heated under reflux for 20 h and subsequently cooled, and MTB ether and dist. water are added. The organic phase is separated off, dried (Na.sub.2SO.sub.4) and evaporated in vacuo. Purification of the residue by column chromatography (eluent toluene) gives ethyl 3-(4-butoxy-3,2,3-trifluoro-4-trifluoro-methoxybiphenyl-2-ylsulfanyl)propionate as yellow oil.

25.4: Butoxy-4,6-difluoro-7-trifluoromethoxydibenzothiophene

(111) ##STR00031##

(112) 2.50 g (22.3 mmol) of potassium tert-butoxide are initially introduced in 30 ml of THF, and a solution of 9.20 g (18.3 mmol) of ethyl 3-(4-butoxy-3,2,3-trifluoro-4-trifluoromethoxybiphenyl-2-ylsulfanyl)propionate in 40 ml of THF is added dropwise at room temp. at such a rate that the temperature does not exceed 30 C. The batch is subsequently heated under reflux for 1 h, cooled, diluted with MTB ether and washed with water. The org. phase is dried over sodium sulfate, the solvent is removed in vacuo, and the residue is filtered through silica gel with toluene. Crystallisation of the crude product from ethanol gives 3-butoxy-4,6-difluoro-7-trifluoromethoxy-dibenzothiophene as colourless crystals of m.p. 121 C.

(113) The following compounds are prepared analogously to Example 25:

(114) TABLE-US-00005 M.p. .sub.1 Phase Ex. R [ C.] .sub. n [mPa .Math. s] sequence 25 n-C.sub.4H.sub.9 121 26 CH.sub.3 27 C.sub.2H.sub.5 135 28 n-C.sub.3H.sub.7 138 29 n-C.sub.5H.sub.11 94 17.92 3.97 0.1413 103 C 94 SmA 105 I 30 n-C.sub.6H.sub.13 114

(115) The following compounds are prepared analogously to Example 25:

(116) TABLE-US-00006 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 31 CH.sub.3 32 C.sub.2H.sub.5 33 n-C.sub.3H.sub.7 34 n-C.sub.4H.sub.9 35 n-C.sub.5H.sub.11 76 36 n-C.sub.6H.sub.13

(117) The following compounds are prepared analogously to Example 25:

(118) TABLE-US-00007 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 37 CH.sub.3 38 C.sub.2H.sub.5 39 n-C.sub.3H.sub.7 40 n-C.sub.4H.sub.9 41 n-C.sub.5H.sub.11 53 19.10 5.37 0.1293 81 42 n-C.sub.6H.sub.13

(119) The following compounds are prepared analogously to Example 25:

(120) TABLE-US-00008 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 43 CH.sub.3 44 C.sub.2H.sub.5 45 n-C.sub.3H.sub.7 46 n-C.sub.4H.sub.9 47 n-C.sub.5H.sub.11 75 0.1492 84 48 n-C.sub.6H.sub.13

(121) The following compounds are prepared analogously to Example 25:

(122) TABLE-US-00009 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 49 CH.sub.3 50 C.sub.2H.sub.5 51 n-C.sub.3H.sub.7 52 n-C.sub.4H.sub.9 53 n-C.sub.5H.sub.11 65 54 n-C.sub.6H.sub.13

(123) The following compounds are prepared analogously to Example 25:

(124) TABLE-US-00010 M.p. .sub.1 Ex. R [ C.] .sub. n [mPa .Math. s] 55 CH.sub.3 56 C.sub.2H.sub.5 57 n-C.sub.3H.sub.7 58 n-C.sub.4H.sub.9 59 n-C.sub.5H.sub.11 112 60 n-C.sub.6H.sub.13

(125) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(126) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

(127) The entire disclosures of all applications, patents and publications, cited herein and of corresponding German Patent Application No. DE 10 2015 004 505.9, filed Apr. 13, 2015 are incorporated by reference herein.

(128) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(129) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.