JPH06316540A - 4-substituted-2,6,3',4',5'-pentafluorobiphenyl derivative, intermediate thereof and their production - Google Patents

Abstract

PURPOSE:To provide a new derivative highly large in dielectric anisotropy and useful as a liquid crystal compound capable of preparing, through its addition, a liquid crystal composition having both high resistivity and voltage retention. CONSTITUTION:The composition of formula I (R is a 1-12C alkyl; n is 0 or 1; Q is CH2CH2 or a single bond; cyclohexane ring of trans conformation), e.g. 4-bromo-2,6,3',4',5'-pentafluorobiphenyl. The compound of the formula I can be obtained by the following process: a compound of formula V is formed from a new intermediate of formula II, and a compound of formula VI is then reacted with the compound of the formula V; and the resultant product is converted to a compound of formula VII and then to a compound of formula VIII. The other objective new intermediate of the formula II can be obtained by reaction between a compound of formula III (M is MgBr or Li) and a compound of formula IV in the presence of a catalyst (esp. pref. a nickel complex).

Description

Detailed Description of the Invention

[0001]

The present invention relates to 4-substituted-2,6, which is a novel compound useful as an electro-optical liquid crystal display material.
The present invention relates to a 3 ′, 4 ′, 5′-pentafluorobiphenyl derivative, a method for producing the same, and a liquid crystal composition containing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices have come to be used in watches, calculators, various measuring instruments, automobile panels, word processors, electronic notebooks, printers, computers, televisions and the like. Typical liquid crystal display methods are TN (twisted nematic) type, STN (super twisted nematic) type, DS (dynamic light scattering) type, GH (guest host) type, and FLC (ferroelectric liquid crystal). ) And the like are known, of which the TN type and the STN type are most widely used at present. Also, as the drive system, the conventional static drive has become more common, and the multiplex drive has become more common, and the simple matrix system and recently the active matrix system have been put into practical use. Of these, the active matrix method can display the highest image quality, has a wide viewing angle, facilitates high definition and colorization, and can also display moving images. Is believed to be.

The liquid crystal material used in this active matrix display system is required to have various characteristics as in the case of a normal liquid crystal display. In particular, (1) it has a high specific resistance and an excellent voltage holding ratio, (2) Threshold voltage (V
_th ) is low, (3) the temperature range of the liquid crystal phase is wide,
(4) It is important that the response is excellent.

Normally, the threshold voltage in liquid crystal display is expressed by the equation (1)

[0005]

[Equation 1]

(In the formula, k is a proportional constant, K is an elastic constant, and Δε is a dielectric anisotropy.). As can be seen from this formula, the threshold voltage is lowered. Therefore, it is necessary to reduce the elastic constant of the liquid crystal material or increase the dielectric anisotropy. Up to now, a substituent such as a cyano group has been introduced into the compound in order to increase the dielectric anisotropy of the liquid crystal compound, but a compound having a cyano group is required to obtain a high specific resistance value and a high voltage holding ratio. Had a tendency to make it difficult. Therefore, in order to increase the dielectric anisotropy, a compound having a fluorine atom in place of the cyano group, such as a 4-fluorophenyl group or 3,4
Compounds having groups such as the -difluorophenyl group have been used.

However, the dielectric anisotropy of such a liquid crystal compound is considerably smaller than that of a compound having a cyano group, and it has been quite difficult to obtain a sufficiently low threshold voltage. Therefore, a compound having a fluorine atom and having a larger dielectric anisotropy has been desired.

At present, as a compound which has a large dielectric anisotropy and can lower the threshold voltage even though it is a fluorine-based compound, for example, a compound having a 3,4,5-trifluorophenyl group is used. Are known. (Described in JP-A-2-233626)

However, the dielectric anisotropy (Δε) of the liquid crystal compound described in the above publication is about +10, which is not sufficiently large as compared with the conventional compound having a cyano group.

Therefore, since it is necessary to further increase the dielectric anisotropy (Δε) of the compound having a fluorine-based group as described above, in addition to the 3,4,5-trifluorophenyl group, an intramolecular It is conceivable to introduce a fluorine atom into another benzene ring, especially at the same position.

Recently, 4-substitution-2,6,3 ', 4',
Formula (A) having a 5′-pentafluorobiphenyl skeleton

[0012]

[Chemical 5]

The following compounds have been reported. (The 14th International Liquid Crystal Society, A-P32) According to it, the dielectric anisotropy of the compound of the formula (A) (Δ
ε) is +25, which is very large. However, the formula (A)
No method for producing the compound of formula (A) is shown at all, and a practical production method for producing the compound of formula (A) easily and in a high yield in a short step using a known compound is desired. Was there.

[0014]

The problem to be solved by the present invention is to prepare a liquid crystal composition having a very large dielectric anisotropy (Δε) and having a high specific resistance and voltage holding ratio by addition. A liquid crystal compound capable of producing the same, an intermediate for producing the same, and a method for producing the liquid crystal compound using the intermediate, further containing the liquid crystal compound, capable of low voltage driving, and particularly suitable for active matrix driving Another object is to provide a liquid crystal composition.

[0015]

In order to solve the above-mentioned problems, the present invention has the general formula (I)

[0016]

[Chemical 6]

(In the formula, R represents an alkyl group having 1 to 12 carbon atoms, preferably a linear alkyl group having 2 to 7 carbon atoms, n represents an integer of 0 or 1, and Q represents −
CH ₂ CH ₂ — or a single bond, and the cyclohexane ring has a trans configuration. 4-substituted-2 represented by
Provided are 3,3 ′, 4 ′, 5′-pentafluorobiphenyl derivatives.

As an intermediate for the production of the compound of the general formula (I), the compound of the formula (II)

[0019]

[Chemical 7]

There is provided a compound represented by: The compound represented by the general formula (I) of the present invention can be produced using the compound of the formula (II), for example, as follows.

[0021]

[Chemical 8]

(In the formula, R, Q and n have the same meanings as in formula (I).) First, 4-bromo-2,6,3 ', 4', 5 represented by formula (II). The'-pentafluorobiphenyl is reacted with magnesium to give a Grignard reagent of formula (V). The Grignard reagent of the formula (V) is reacted with the cyclohexanone derivative of the general formula (VI), the obtained cyclohexanol derivative is dehydrated to a cyclohexene derivative, and then hydrogenated. The compound of general formula (I) can be obtained by performing isomerization to the trans form accordingly.

Since the bromine at the 4-position of the compound of formula (II) is highly reactive, a lithium reactant obtained by reacting butyllithium or the like is used in place of the compound of formula (V). May be.

The compound of the formula (II) of the present invention is not limited to the compound of the general formula (I) of the present invention, but is also useful as an intermediate for the production of a liquid crystal compound having a similar skeleton. The compound of A) and its analogs can also be produced as follows.

[0025]

[Chemical 9]

(In the formula, R and n have the same meanings as in the general formula (I).) First, the compound represented by the formula (II) is reacted with magnesium to form a Grignard reactant of the formula (V). To do. By reacting the compound of the formula (V) with a trans-4-substituted cyclohexaneacetaldehyde derivative of the general formula (VII), and then dehydrating and hydrogenating the same as in the case of the compound of the general formula (I),
Compounds of general formula (VIII), including compounds of formula (A), can be obtained. The general formula (VI
The compound of I) can be represented by, for example, Q = in the general formula (VI)
General formula (VIa) which is a single bond

[0027]

[Chemical 10]

(Wherein R and n have the same meanings as in formula (I)), a trans-4-substituted cyclohexanone derivative represented by formula (IX)

[0029]

Embedded image CH ₃ OCH═PPh ₃ (IX) (wherein Ph represents a phenyl group) and can be obtained by reacting the Wittig reaction agent twice in succession.

Here, the compound of formula (II) of the present invention is
General formula (III)

[0031]

[Chemical 12]

(Wherein, M represents MgBr or Li), and an organic metal reactant represented by the formula (IV)

[0033]

[Chemical 13]

1-iodo-4-bromo-represented by
It can be obtained by reacting 2,6-difluorobenzene in the presence of a catalyst, and the present invention provides a compound of the formula (I
Also provided is a method for preparing the compound of I).

The organometallic reagent of formula (III) used here is commercially available 1-bromo-3, when M = MgBr.
It can be obtained by reacting 4,5-trifluorobenzene with magnesium in a solvent, and when M = Li, it can be obtained by reacting with alkyllithium such as butyllithium. Also, 1-iodo-4-
Bromo-2,6-difluorobenzene is commercially available and can be easily produced from 4-bromo-2,6-difluoroaniline.

As the catalyst that can be used for producing the compound of the formula (II), for example, nickel complex or palladium complex is preferable, but dichlorobis (diphenylphosphino) ethane nickel (I
I), nickel complexes such as dichloro [1,3-bis (diphenylphosphino) propane] nickel (II) and dichlorobis (triphenylphosphine) nickel (II), and palladium such as tetrakis (triphenylphosphine) palladium (0). Complexes are preferred, especially nickel (II) complexes.

Typical examples of the compounds represented by the general formula (I) thus obtained are shown in Table 1 below.

[0038]

[Table 1]

(In the table, Cr represents a crystalline phase, N represents a nematic phase, and I represents an isotropic liquid phase.)

The compound of the general formula (I) of the present invention can be suitably used in the state of a mixture with other nematic liquid crystal compounds, especially as a material of a field effect display cell of TN type or STN type. . Moreover, even though it has a very large dielectric anisotropy (Δε), it does not have a strong polar group such as a cyano group or an ester bond in its molecule, so this compound is used to obtain a high specific resistance and voltage holding ratio. A liquid crystal composition having a can be easily obtained. Therefore, it is particularly suitable as a constituent component of an active matrix driving liquid crystal material.

The liquid crystal composition containing the compound represented by the general formula (I) of the present invention is also shown in Examples below,
It has excellent characteristics as shown below. As a liquid crystal composition for an active matrix, a base liquid crystal (a) having low viscosity and high-speed response

[0042]

[Chemical 14]

When T was prepared, T _NI (upper limit temperature of nematic phase) was 116 ° C., and dielectric anisotropy (Δε) was +4.8. Further, the host liquid crystal (a) was sealed in a TN cell having a cell thickness of 4.5 μm to prepare a liquid crystal display element, and the threshold voltage at 20 ° C. was measured.
It was 1.88V.

Next, 85% by weight of this host liquid crystal (a) and No. 1 in Table 1 were used. 1

[0045]

[Chemical 15]

When a liquid crystal composition containing 15% by weight of the compound of 1 was prepared, T _NI was slightly lowered to 100.5 ° C., but the dielectric anisotropy (Δε) was increased to +6.7, and the same was done. A liquid crystal display device was produced and the threshold voltage at 20 ° C. was measured.

Next, 90% by weight of the same host liquid crystal (a) and No. 1 in Table 1 were used. Two

[0048]

[Chemical 16]

When a liquid crystal composition containing 10% by weight of the compound of T was prepared, T _NI greatly increased to 125 ° C.
The dielectric anisotropy (Δε) was as large as +6.3, and when a liquid crystal display element was similarly prepared and the threshold voltage was measured, it was 1.78 V, which was 0.1 V compared with the base liquid crystal (a). Also fell.

As described above, by using the compound represented by the general formula (I) of the present invention, the dielectric anisotropy (Δε)
It is possible to easily obtain a liquid crystal composition having a large _{Vth and} a low V _th , which is suitable for driving an active matrix.

In the liquid crystal composition of the present invention, preferable representative examples of the nematic liquid crystal compound which can be used by mixing with the compound represented by the general formula (I) are:
For example, 4-substituted benzoic acid 4-substituted phenyl ester,
4-Substituted cyclohexanecarboxylic acid 4-substituted phenyl ester, 4-substituted cyclohexanecarboxylic acid 4'-substituted biphenylyl ester, 4- (4-substituted cyclohexanecarbonyloxy) benzoic acid 4-substituted phenyl ester, 4- (4-substituted Cyclohexyl) benzoic acid 4-substituted phenyl ester, 4- (4-substituted cyclohexyl) benzoic acid 4-substituted cyclohexyl ester, 4,4′-substituted biphenyl, 1- (4-substituted phenyl) -4-substituted cyclohexane, 4, 4 "-substituted terphenyl, 1-
(4′-Substituted biphenylyl) -4-substituted cyclohexane, 1- (4-substituted cyclohexyl) -4- (4-substituted phenyl) cyclohexane, 2- (4-substituted phenyl)
-5-substituted pyrimidine, 2- (4-substituted biphenylyl)
-5-substituted pyrimidine, 1- (4-substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane, 1-
(4-Substituted cyclohexyl) -2- (4-substituted phenyl) ethane, 1- [4- (4-substituted cyclohexyl) cyclohexyl] -2- (4-substituted phenyl) ethane, 1
-[4- (4-Substituted phenyl) cyclohexyl] -2-
(4-Substituted cyclohexyl) ethane, 1- (4-substituted phenyl) -2- (4-substituted phenyl) ethyne, 1- [4
Examples include-(4-substituted cyclohexyl)]-2- (4-substituted phenyl) ethyne and the like.

Especially for active matrix, 4,4'-substituted biphenyl, 1- (4-substituted phenyl) -4-substituted cyclohexane, 4,4 "-substituted terphenyl, 1- (4'-substituted biphenylyl ) -4-Substituted cyclohexane, 1- (4-substituted cyclohexyl) -4-
(4-substituted phenyl) cyclohexane, 1- (4-substituted cyclohexyl) -2- (4-substituted cyclohexyl) ethane, 1- (4-substituted cyclohexyl) -2- (4-substituted phenyl) ethane, 1- [4 -(4-Substituted cyclohexyl) cyclohexyl] -2- (4-substituted phenyl) ethane, 1- [4- (4-substituted phenyl) cyclohexyl] -2- (4-substituted cyclohexyl) ethane, 1-
(4-Substituted phenyl) -2- (4-substituted phenyl) ethyne, 1- [4- (4-substituted cyclohexyl)]-2-
(4-Substituted phenyl) ethyne and the like are preferable.

[0053]

EXAMPLES The present invention will be further described below by showing Examples of the present invention. However, the invention is not limited to these examples.

The structure of each compound is determined by nuclear magnetic resonance spectroscopy.
Torr (NMR), mass spectrum (MS), infrared absorption spectrum
It was confirmed by a vector (IR). CD in NMR
Cl ₃Represents a solvent, d is a doublet, and dd is a doubled double.
Represents a line and J represents a coupling constant. In MS
K M⁺Represents the parent peak, and the parentheses in ()
Represents relative intensity. KBr in IR indicates tablet molding
Forget

Example 1 4-bromo-2,6
3 ′, 4 ′, 5′-pentafluorobiphenyl (formula (I
Synthesis of compound I))

[0056]

[Chemical 17]

Dry tetrahydrofuran (THF) 1
1.7 g of scraped magnesium was added to 5 ml. 1-bromo-3,4,5-trifluorobenzene 1
A solution of 5.0 g of THF in 75 ml was added dropwise at such a rate that a gentle reflux was maintained. Further, the mixture was heated and stirred at a reflux temperature for 2 hours to synthesize a Grignard reactant. After cooling to room temperature, excess unreacted magnesium was filtered off.

15.0 g of 1-iodo-4-bromo-2,6-difluorobenzene and 0.25 g of dichlorobis (diphenylphosphino) ethane nickel (II) were added to T.
It was dissolved in 75 ml of HF. The Grignard reactant obtained above was added dropwise to this solution at room temperature for 30 minutes. After the dropping, the mixture was further heated and stirred at reflux temperature for 3 hours, and then allowed to cool to room temperature. Dilute hydrochloric acid was added until the aqueous layer was acidic, then 200 ml of ethyl acetate was added. Then, the organic layer was separated, washed with water, and dried over anhydrous sodium sulfate. After distilling off the solvent, the obtained residue was purified by silica gel column chromatography (hexane) and recrystallized from methanol to give 4-bromo-2,6,3 ′,
White crystals of 4 ', 5'-pentafluorobiphenyl 8.
5 g was obtained.

Melting point: 72 ° C. IR (KBr): 1620, 1540, 1400, 12
50, 1190, 1100, 1050, 1020, 90
0,860,840 cm ^-1 NMR (CDCl ₃ ): δ = 7.09 (dd, J = 7.
2 and 7.2 Hz, 2 H), 7.21 (d, J = 7.
2Hz, 2H) MS: m / e = 324 (99), 322 (100,
M ⁺ ), 242 (97), 224 (68), 193 (3
2), 161 (32), 121 (23), 96 (20)

(Example 2) 1- (3,4,5-trifluorophenyl) -4- (trans-4-propylcyclohexyl) -2,6-difluorobenzene (Compound No. 1 in Table 1) Synthesis of

[0061]

[Chemical 18]

10 ml of THF and 0.76 of magnesium
4-bromo-2 obtained in Example 1,
6,3 ′, 4 ′, 5′-pentafluorobiphenyl 8.
A solution of 5 g of THF in 50 ml was added dropwise over 30 minutes. After the dropping, the mixture was heated and refluxed for another hour to prepare a Grignard reaction agent. After allowing to cool, a solution of 4-propylcyclohexanone (4.4 g) in THF (20 ml) was added dropwise at 25 ° C over 30 minutes. After heating under reflux for 1 hour, water and then dilute hydrochloric acid were added. The reaction product was extracted with 100 ml of ethyl acetate, and the organic phase was washed with water and then with saturated saline.

1.0 g of p-toluenesulfonic acid was added thereto, and the mixture was heated under reflux for 1 hour. After allowing to cool, the reaction solution was washed with an aqueous solution of sodium hydrogencarbonate and then with water, and dehydrated and dried over anhydrous sodium hydrogensulfate. The crude product obtained by distilling off the solvent was recrystallized from ethanol to give 1- (3
4,5-Trifluorophenyl) -4- (trans-4
2.8 g of -propyl-1-cyclohexenyl) -2,6-difluorobenzene were obtained. This is ethyl acetate 100
It was dissolved in ml, 300 mg of 5% palladium-carbon was added, and the mixture was stirred under a hydrogen atmosphere at atmospheric pressure and 25 ° C. for 6 hours. After completion of the reaction, the catalyst was filtered off, the solvent was distilled off, and the obtained crude product was purified by silica gel column chromatography to obtain 1- (3,4,5-trifluorophenyl).
-4- (trans-4-propylcyclohexyl)-
Weight ratio of 2,6-difluorobenzene and 1- (3,4,5-trifluorophenyl) -4- (cis-4-propylcyclohexyl) -2,6-difluorobenzene 3
2.8 g of a 6/64 mixture was obtained. This was recrystallized twice from ethanol to give 0.8 g of 1- (3,4,5-trifluorophenyl) -4- (trans-4-propylcyclohexyl) -2,6-difluorobenzene as white crystals.
Got Melting point: 121 ° C

(Example 3) 1- (3,4,5-trifluorophenyl) -4- [trans-4- (trans-
4-propylcyclohexyl) cyclohexyl] -2,
6-difluorobenzene (Compound No. 2 in Table 1)
Synthesis of

[0065]

[Chemical 19]

0.46 g of magnesium and 5 ml of THF
4-bromo-2,6, obtained in Example 1,
5.5 g of 3 ', 4', 5'-pentafluorobiphenyl
A THF 30 ml solution of was added dropwise over 30 minutes. After dropping
The mixture was heated under reflux for 1 hour to prepare a Grignard reactant. After allowing to cool, 25 g of 4- (trans-4-propylcyclohexyl) cyclohexanone 3.8 g of THF 20 m
1 solution was added dropwise over 30 minutes. After heating under reflux for 1 hour,
Water was added followed by dilute hydrochloric acid. The reaction product is ethyl acetate 1
It was extracted with 00 ml and the organic phase was washed with water and then with saturated saline.

To this was added 1.0 g of p-toluenesulfonic acid, and the mixture was heated under reflux for 1 hour. After allowing to cool, the reaction solution was washed with an aqueous solution of sodium hydrogencarbonate and then with water, and dehydrated and dried over anhydrous sodium hydrogensulfate. The crude product obtained by distilling off the solvent was recrystallized from ethanol to give 1- (3
4,5-Trifluorophenyl) -4- [trans-4
-(Trans-4-propylcyclohexyl) -1-cyclohexenyl] -2,6-difluorobenzene 4.8
g was obtained. Dissolve this in 150 ml of ethyl acetate and add 5%
500 mg of palladium-carbon was added, and the mixture was stirred under a hydrogen atmosphere at atmospheric pressure and 25 ° C. for 6 hours. After completion of the reaction, the catalyst was filtered off and the solvent was distilled off to obtain a crude product, which was purified by silica gel column chromatography to give 1- (3.
4,5-Trifluorophenyl) -4- [trans-4
-(Trans-4-propylcyclohexyl) cyclohexyl] -2,6-difluorobenzene and 1- (3
4,5-trifluorophenyl) -4- [cis-4-
(Trans-4-propylcyclohexyl) cyclohexyl] -2,6-difluorobenzene weight ratio 33/6
4.6 g of 7 mixture was obtained. This was recrystallized twice from ethanol to give 1- (3,4,5-trifluorophenyl) -4- [trans-4- (trans-4-propylcyclohexyl) cyclohexyl] -2,6-difluorobenzene. 1.8 g of white crystals were obtained. Phase transition temperature: 151 ° C (Cr → N), 234 ° C (N-
I)

Reference Example 1- (3,4,5-trifluorophenyl) -4- [2- (trans-4-pentylcyclohexyl) ethyl] -2,6-difluorobenzene (of the general formula (VIII)) Compound) Synthesis

[0069]

[Chemical 20]

1- (3,4,5-Trifluorophenyl) -in the same manner as in Example 2 except that trans-4-pentylcyclohexaneacetaldehyde was used in place of 4-propylcyclohexanone. Four
White crystals of-[2- (trans-4-pentylcyclohexyl) ethyl] -2,6-difluorobenzene were obtained. Phase transition temperature: 66 ° C (Cr → I), 65 ° C (N-I)

Example 4 Preparation of Liquid Crystal Composition (1) As a liquid crystal composition for an active matrix, a base liquid crystal (a) having low viscosity and fast response

[0072]

[Chemical 21]

Was prepared. The T _NI , the dielectric anisotropy (Δε), and the threshold voltage (V _th ) of the TN cell having a cell thickness of 4.5 μm at 20 ° C. were measured as follows. .

T _NI : 116 ° C. Δε: +4.8 V _th : 1.88 V 85% by weight of this host liquid crystal (a) and obtained in Example 2.

[0075]

[Chemical formula 22]

A liquid crystal composition containing 15% by weight of the compound of was prepared, and T _NI , Δε and V _th were measured in the same manner. T _NI : 100.5 ° C. Δε: +6.7 V _th : 1.51 V. It can be understood that the compound No. 1 has an excellent effect of increasing the dielectric anisotropy (Δε) of the liquid crystal composition by addition and further greatly reducing the threshold voltage.

Example 5 Preparation of Liquid Crystal Composition (2) 90% by weight of the base liquid crystal (a) and the liquid crystal composition obtained in Example 3 were obtained.

[0078]

[Chemical formula 23]

A liquid crystal composition containing 10% by weight of the compound of (1) was prepared, and T _NI , Δε and V _th were measured in the same manner. T _NI : 125 ° C. Δε: +6.3 V _th : 1.78 V The compound of No. 2 has an excellent effect of increasing the nematic phase maximum temperature of the liquid crystal composition and increasing the dielectric anisotropy (Δε) at the same time as decreasing the threshold voltage by 0.1 V by addition. Can be understood to have.

[0080]

INDUSTRIAL APPLICABILITY The compound represented by the general formula (I) of the present invention is 4-bromo-2,6, as shown in Examples.
It can be easily industrially produced using 3 ', 4', 5'-pentafluorobiphenyl. Further, since a strong polar group such as a cyano group or an ester bond does not exist in the molecule, a liquid crystal composition having high specific resistance and voltage holding ratio can be easily obtained by addition. Moreover, it has excellent characteristics that the dielectric constant anisotropy of the composition is increased and the threshold voltage is greatly reduced. Therefore, it is useful as a liquid crystal material for various liquid crystal display elements, particularly for active matrix driven liquid crystal display elements.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // C07B 61/00 300

Claims (5)

[Claims] 1. A compound represented by the general formula (I): (In the formula, R represents an alkyl group having 1 to 12 carbon atoms, n represents an integer of 0 or 1, and Q represents —CH ₂ CH ₂ —.
Alternatively, it represents a single bond, and the cyclohexane ring is in the trans configuration. ) The compound represented by. 2. Formula (II): A compound represented by. 3. A compound represented by the general formula (III): (In the formula, M represents MgBr or Li) and a compound represented by the formula (IV): The method for producing the compound represented by the formula (II) according to claim 2, wherein the compound represented by the formula (1) is reacted in the presence of a catalyst. 4. The method according to claim 3, wherein the catalyst is a nickel complex. 5. A liquid crystal composition containing the compound represented by formula (I) according to claim 1.