DIBENZOFURAN DERIVATIVES AND DIBENZOTHIOPHENE DERIVATIVES

Abstract

The invention relates to compounds of the formula I

##STR00001##

in which groups and parameters that occur have the definitions given in Claim 1, to the preparation thereof, to the use thereof as components in liquid-crystalline media and to electrooptical display elements comprising the liquid-crystalline media of the invention.

Claims

1. Compound of the formula I ##STR00021## in which W is —O— or —S—, Y.sup.1 and Y.sup.2 are independently H, F, Cl, CN or CF.sub.3, R.sup.11 and R.sup.12 are independently H, an unsubstituted, mono-CN- or —CF.sub.3-substituted or at least mono-halogen-substituted alkyl- or alkenyl radical having up to 15 carbon atoms, where one or more CH.sub.2 groups in these radicals may also be replaced by —O, S, —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —OC—O— or —O—CO— such that oxygen atoms are not bonded directly to one another, R.sup.2 is an unsubstituted, mono-CN- or —CF.sub.3-substituted or at least mono-halogen-substituted alkyl- or alkenyl radical having up to 15 carbon atoms, where one or more CH.sub.2 groups in these radicals may also be replaced by —O—, —S—, —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —OC—O— or —O—CO— such that oxygen atoms are not bonded directly to one another, and also H, halogen, CN, SCN or SF.sub.5. A.sup.1 is a 1,3-cyclopentylene radical which may be monounsaturated and which may be mono- or polysubstituted by an L group, B.sup.1 is the same or different at each instance and is a) a 1,4-phenylene radical in which one or two CH groups may be replaced by N, b) a 1,4-cyclohexenylene or 1,4-cyclohexylene radical in which one or two nonadjacent CH.sub.2 groups may be replaced by —O— or —S—, a cyclobutane-1,3-diyl radical, c) a radical from the group of 1,4-bicyclo[2,2,2]-octylene, spiro[3.3]heptane-2,6-diyl, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, thiophene-2,5-diyl, where the groups a), b) and c) may be mono- or polysubstituted by an L group, L at each instance is independently F, Cl, CN, SCN, SF.sub.5 or straight-chain or branched, in each case optionally fluorinated alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 carbon atoms, Z.sup.1 and Z.sup.2 are each independently a single bond, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH.sub.2O—, —OCH.sub.2—, —CH.sub.2S—, —SCH.sub.2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C≡C—, n is 0, 1 or 2.

2. Compound of the formula I according to claim 1, characterized in that B.sup.1 is selected from the group of ring elements of the formulae ##STR00022##

3. Compound of the formula I according to claim 1, characterized in that W is —S—.

4. Compound of the formula I according to claim 1, characterized in that at least one of the Y.sup.1 and Y.sup.2 radicals is not H.

5. Compound of the formula I according to claim 1, characterized in that Y.sup.1 and Y.sup.2 are both F.

6. Compound of the formula I according to claim 1, characterized in that the compound is selected from the group of compounds of the formulae I-1 and I-2 ##STR00023## where groups that occur have the definitions given in claim 1.

7. Compound according to claim 1, characterized in that the group ##STR00024##

8. Compound according to claim 1, characterized in that R.sup.2 is methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl or n-heptyl.

9. Compound according to claim 1, characterized in that R.sup.2 is methoxy, ethoxy, n-propoxy, n-butoxy, n-pentoxy, n-hexoxy or n-heptoxy.

10. Compound according to claim 1, characterized in that R.sup.2 is F, Cl, CN, SCN, SF.sub.5, CF.sub.2H, CF.sub.3, OCF.sub.2H, OCF.sub.3 or —OCH═CF.sub.2.

11. Compound of the formula II ##STR00025## in which R.sup.11 and R.sup.12 are independently H, an unsubstituted, mono-CN- or —CF.sub.3-substituted or at least mono-halogen-substituted alkyl- or alkenyl radical having up to 15 carbon atoms, where one or more CH.sub.2 groups in these radicals may also be replaced by —O—, —S—, —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —OC—O— or —O—CO— such that oxygen atoms are not bonded directly to one another, Y.sup.1 and Y.sup.2 are independently H, F, Cl, CN or CF.sub.3, W is —O— or —S—, Z.sup.2 are each independently a single bond, —CF.sub.2O—, —OCF.sub.2—, —CF.sub.2S—, —SCF.sub.2—, —CH.sub.2CH.sub.2—, —CF.sub.2CF.sub.2—, —CF.sub.2CH.sub.2—, —CH.sub.2CF.sub.2—, —CHF—CHF—, —C(O)O—, —OC(O)—, —CH.sub.2O—, —OCH.sub.2—, —CH.sub.2S—, —SCH.sub.2—, —CF═CH—, —CH═CF—, —CF═CF—, —CH═CH— or —C≡C—, B.sup.1 is the same or different at each instance and is a) a 1,4-phenylene radical in which one or two CH groups may be replaced by N, R.sup.2 is an unsubstituted, mono-CN- or —CF.sub.3-substituted or at least mono-halogen-substituted alkyl- or alkenyl radical having up to 15 carbon atoms, where one or more CH.sub.2 groups in these radicals may also be replaced by —O—, —S—, —C≡C—, —CF.sub.2O—, —OCF.sub.2—, —OC—O— or —O—CO— such that oxygen atoms are not bonded directly to one another, and also H, halogen, CN, SCN or SF.sub.5. n is 0, 1 or 2.

12. Process for preparing compounds of the formula I according claim 1, characterized in that a compound of the formula II ##STR00026## is converted by elimination of water to a compound of the formula I.

13. (canceled)

14. Liquid-crystalline medium, characterized in that it comprises one or more compounds according to claim 1.

15. Electrooptical display element, characterized in that it comprises a liquid-crystalline medium according to claim 14.

Description

SUBSTANCE EXAMPLE 1

1.1 1-(7-Ethoxy-4,6-difluorodibenzothiophen-3-yl)cyclopentanol (3)

[0117] ##STR00018##

[0118] 5.3 g (20 mmol) of the dibenzothiophene 1 are dissolved in 50 ml of THF and, at −70° C., 16.9 ml of butyllithium (15%) in hexane (26 mmol) are added. After 1 h at −70° C., 2.3 g (30 mmol) of cyclopentanone (2), dissolved in 20 ml of THF, are added. The cooling is removed and, at −20° C., water and MTB ether are added to the mixture. The aqueous phase is extracted with MTB ether, and the combined organic phases are dried over sodium sulfate, filtered and concentrated. The residue is filtered through silica gel (BuCl/EA) and the product fractions are concentrated. The residue obtained (2.5 g (81%)) (3) is used in the subsequent stage without further purification.

1.2 3-(Cyclopenten-1-yl)-7-ethoxy-4,6-difluorodibenzothiophene (4)

[0119] ##STR00019##

[0120] 3.5 g (10 mmol) of alcohol 3 are dissolved in 80 ml of toluene, 200 mg of p-TsOH are added and the mixture is heated to boiling on a water trap. The cooled mixture is filtered through silica gel and eluted with n-heptane. The residue obtained after concentration of the filtrate is crystallized from ethanol/toluene. This affords 3-(cyclopenten-1-yl)-7-ethoxy-4,6-difluorodibenzothiophene as colourless crystals of m.p. 153° C.

[0121] Δε=−8.24

[0122] Δn=0.2815

[0123] γ.sub.1=235 m Pa s

EXAMPLE 2: 3-(CYCLOPENTYL)-7-ETHOXY-4,6-DIFLUORODIBENZOTHIOPHENE (4)

[0124] ##STR00020##

[0125] 5.3 g (20 mmol) of the cyclopentene 4 are dissolved in 55 ml of THF and hydrogenated to completion over Pd/C. The solution is then filtered and concentrated, and the residue is filtered through silica gel with n-heptane/EA and recrystallized from ethanol and then from heptane. This affords 3-(cyclopentyl)-7-ethoxy-4,6-difluorodibenzothiophene as colourless crystals of m.p. 110° C.

[0126] Δε=−8.41

[0127] Δn=0.2035

[0128] γ.sub.1=276 m Pa s