JP2002284722A - Method for producing 5,6,7-trifluoro-1,2,3,4- tetrahydronaphthalene derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for industrially easily producing a trifluorotetrahydronaphthalene derivative useful as a liquid display material at a low cost. SOLUTION: This method for producing the trifluorotetrahydronaphthalene derivative of the general formula II comprises converting a difluorotetrahydronaphthalene derivative into a lithio compound and then fluorinating the lithio compound. Concretely, 5,6,7-trifluoro-2-(trans-4- propylcyclohexyl)-1,2,3,4tetrahydronaphthalene is synthesized according to the reaction formula 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the production of trifluorotetrahydronaphthalene useful as a liquid crystal display material.

[0002]

A liquid crystal display device, watch, including the calculator, various measuring instruments, automotive panels, word processors, electronic notebooks, printers, computers, have come to be used in televisions and the like. Typical liquid crystal display methods are TN (twisted nematic), STN (super twisted nematic), DS (dynamic light scattering), GH (guest / host), and FLC that can respond at high speed. (Ferroelectric liquid crystal)
And AFLC (antiferroelectric liquid crystal). As a driving method, a multiplex driving has been generally used instead of the conventional static driving, and a simple matrix method, more recently, an active matrix method has been put to practical use.

As the liquid crystal material used for these, a great variety of liquid crystal compounds have been synthesized so far, and these are used according to the display system, the driving system, or the application. However, demands for improving the performance of liquid crystal display elements (improvement of display quality, enlargement of display screen, etc.) are increasing year by year, and new liquid crystal compounds are being developed to satisfy the demands.

A liquid crystal compound is usually composed of a central skeleton part called a core and terminal parts on both sides. Usually, the ring structure constituting the core portion of the liquid crystal compound includes a 1,4-phenylene group (which may be substituted with one or two halogen atoms, a cyano group, a methyl group, or the like) and a trans-
The 1,4-cyclohexylene group accounts for the majority. However, liquid crystal compounds composed only of 1,4-phenylene group and trans-1,4-cyclohexylene group have limited types and properties, and it is impossible to meet the above requirements only with them. It is a fact.

The ring structure other than the 1,4-phenylene group and the trans-1,4-cyclohexylene group includes, for example, pyridine-
Heterocyclic systems such as 2,5-diyl group, pyrimidine-2,5-diyl group, 1,3-dioxane-trans-2,5-diyl group, and trans
-Decahydronaphthalene-2,6-diyl group, naphthalene-2,6
-Diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, bicyclo [2.2.2] octane-1,4-diyl group, spiro
[3.3] Condensed ring systems such as heptane-2,6-diyl group are also being studied, but are currently in practical use due to problems in production (technology, cost, etc.) and stability problems. Things are only a few.

The present inventors have proposed compounds (IIa) and (IIb)

Embedded image And other novel trifluorotetrahydronaphthalene derivatives, which show very excellent electro-optical properties,
In particular, it has been reported that it is useful for reducing the threshold voltage (Vth) (Japanese Patent Application No. 2001-10991, Japanese Patent Application No. 2000-191159, Japanese Patent Application No. 2000-191159).
-37833).

However, since the yield in producing these compounds is not sufficiently high, they cannot be said to be compounds which can be obtained at a low cost in terms of production cost. Therefore, an easy and inexpensive method for producing a trifluorotetrahydronaphthalene derivative is required.

[0008]

An object of the present invention is to provide an easy and inexpensive method for producing a trifluorotetrahydronaphthalene derivative.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of diligent studies to solve the above-mentioned problems. And completed the present invention.

That is, the present invention provides a compound represented by the general formula (I)

[0011]

Embedded image (Wherein, R is a saturated or unsaturated alkyl having 1 to 20 carbon atoms which may be substituted by one or more fluorine atoms and / or an alkoxyl group having 1 to 7 carbon atoms, and which may contain a branched chain) represents a group or an alkoxyl group, linking group X, Y is a single _{bond, -CH 2 CH 2 -, -} CH = CH -, - CH (CH 3) CH 2 -, -
CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )-, -C≡C-,-(CH ₂ ) ₄ -,-
Represents CH ₂ O— or —OCH ₂ —, wherein ring A and ring B are trans
1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2.2] octane-1,4-diyl group And a 1,4-phenylene group which may be substituted by one or two fluorine atoms, a pyridine-2,5-diyl group, a pyrimidine-2,5-
Diyl group, pyrazine-2,5-diyl group and pyridazine-3,
Represents a 6-diyl group, and n represents an integer of 0 to 2. Wherein the difluorotetrahydronaphthalene derivative represented by) is lithiated and then fluorinated

[0012]

Embedded image (Wherein, R is a saturated or unsaturated alkyl having 1 to 20 carbon atoms which may be substituted by one or more fluorine atoms and / or an alkoxyl group having 1 to 7 carbon atoms, and which may contain a branched chain) represents a group or an alkoxyl group, linking group X, Y is a single _{bond, -CH 2 CH 2 -, -} CH = CH -, - CH (CH 3) CH 2 -, -
CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )-, -C≡C-,-(CH ₂ ) ₄ -,-
Represents CH ₂ O— or —OCH ₂ —, wherein ring A and ring B are trans
1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2.2] octane-1,4-diyl group And a 1,4-phenylene group which may be substituted by one or two fluorine atoms, a pyridine-2,5-diyl group, a pyrimidine-2,5-
Diyl group, pyrazine-2,5-diyl group and pyridazine-3,
Represents a 6-diyl group, and n represents an integer of 0 to 2. The present invention provides a method for producing a trifluorotetrahydronaphthalene derivative represented by the following formula:

[0013]

DETAILED DESCRIPTION OF THE INVENTION As described above, for the production of a trifluorotetrahydronaphthalene derivative, the reaction can be carried out under the following conditions.

Compounds (I) and (II) in this reaction
R may be substituted with one or more fluorine atoms and / or alkoxyl groups having 1 to 7 carbon atoms, and may be a saturated or unsaturated alkyl group or alkoxyl group having 1 to 20 carbon atoms which may contain a branched chain. Represents a group, examples of which include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, undecyl, dodecyl,
Linear alkyl group such as tridecyl group, 1-methylethyl group, 1-methylpropyl group, 2-methylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 3-methylbutyl group, 1-
Methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1-methylhexyl, 2-
Methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 1-methylheptyl, 2-
Methylheptyl group, 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 6-methylheptyl group, 1-
Methyloctyl, 2-methyloctyl, 3-methyloctyl, 4-methyloctyl, 5-methyloctyl, 6-
Methyloctyl group, 7-methyloctyl group, 1-ethylpropyl group, 1-ethylbutyl group, branched alkyl groups such as 2-ethylbutyl group, ethenyl group, 1-propenyl group, 2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group,
1-pentenyl group, 2-pentenyl group, 3-pentenyl group, 4-
Pentenyl group, 1-hexenyl group, 2-hexenyl group, 3-hexenyl group, 4-hexenyl group, 5-hexenyl group, 1-heptenyl group, 2-heptenyl group, 3-heptenyl group, 4-heptenyl group, 5- Unsaturated alkyl groups such as a heptenyl group and a 6-heptenyl group, and alkyl groups substituted with a fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms, methoxy group, ethoxy group, propoxy group, butoxy group, pentyl Oxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, undecyloxy group, dodecyloxy group, linear alkoxyl group such as tridecyloxy group, 1-methylethyloxy group, 1 -Methylpropyloxy group, 2-methylpropyloxy group, 1-methylbutyloxy group, 2-methylbutyloxy group, 3-methylbutyloxy group Si group, 1-methylpentyloxy group, 2-methylpentyloxy group, 3-methylpentyloxy group, 4-methylpentyloxy group, 1-methylhexyloxy group, 2-methylhexyloxy group, 3-methylhexyloxy Group, 4-methylhexyloxy group, 5-methylhexyloxy group, 1-methylheptyloxy group, 2-
A methylheptyloxy group, a 3-methylheptyloxy group,
4-methylheptyloxy group, 5-methylheptyloxy group, 6-methylheptyloxy group, 1-methyloctyloxy group, 2-methyloctyloxy group, 3-methyloctyloxy group, 4-methyloctyloxy group, 5 -Methyloctyloxy group, 6-methyloctyloxy group, 7-methyloctyloxy group, 1-ethylpropyloxy group, 1-ethylbutyloxy group, 2-ethylbutyloxy group and other branched alkoxyl groups, ethenyloxy group, 1-propenyloxy group,
2-propenyloxy group, 1-butenyloxy group, 2-butenyloxy group, 3-butenyloxy group, 1-pentenyloxy group, 2-pentenyloxy group, 3-pentenyloxy group, 4-
Pentenyloxy group, 1-hexenyloxy group, 2-hexenyloxy group, 3-hexenyloxy group, 4-hexenyloxy group, 5-hexenyloxy group, 1-heptenyloxy group, 2-heptenyloxy group, 3-heptenyloxy group, 4 -
Unsaturated alkoxyl groups such as a heptenyloxy group, a 5-heptenyloxy group and a 6-heptenyloxy group, and alkoxyl groups obtained by substituting them with a fluorine atom and / or an alkoxyl group having 1 to 7 carbon atoms. Of fluorine and / or carbon atoms of 1
And may be substituted by an alkoxyl group of 7 to
Saturated or unsaturated carbon number of 1 to 20 which may contain a branched chain
Is preferred, and a saturated or unsaturated alkyl group having 1 to 20 carbon atoms which may contain a branched chain is particularly preferred.

Compounds (I) and (II) in this reaction
In the above, the connecting groups X and Y are a single bond, -CH_TwoCH_Two-, -CH = CH
-, -CH (CH_Three) CH_Two-, -CH_TwoCH (CH_Three)-, -CH (CH_Three) CH (CH_Three)-,-
C≡C-,-(CH_Two)_Four-, -CH_TwoO- or -OCH_Two-Listen
Can be a single bond or -CH _TwoCH_Two-Is preferred.

Compounds (I) and (II) in this reaction
In the ring A and ring B as a trans-1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2. 2] octane-1,4-diyl group and 1,4-phenylene group optionally substituted by one or two fluorine atoms, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine A -2,5-diyl group and a pyridazine-3,6-diyl group, but a trans-1,4-cyclohexylene group, a trans-decahydronaphthalene-2,6-diyl group, a trans-1, 3-dioxane-2,5-diyl group, bicyclo [2.2.
2] octane-1,4-diyl group and 1,4-phenylene group are preferred, trans-1,4-cyclohexylene group, trans-
Decahydronaphthalene-2,6-diyl group and bicyclo [2.
2.2] Octane-1,4-diyl groups are particularly preferred and trans-
A 1,4-cyclohexylene group is most preferred.

As the lithiating agent in this reaction, alkyllithiums such as methyllithium, ethyllithium, propyllithium, butyllithium, s-butyllithium, t-butyllithium, lithium diisopropylopyramide,
Lithium amides such as lithium diethylamide and lithium hexamethyldisilazide can be used, but butyllithium, s-butyllithium and lithium diisopropylopyramide are preferred from the viewpoint of activity and availability. Further, a base such as potassium t-butoxide and sodium t-butoxide can be used in combination.

As the solvent in the present reaction, pentane,
Saturated hydrocarbons such as hexane, cyclohexane, heptane, octane, and decahydronaphthalene; ether solvents such as diethyl ether, methyl-t-butyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, and 1,4-dioxane; benzene, toluene, and xylene And the like can be used alone or in combination. Also, hexamethylphosphoric triamide,
N, N-dimethylformamide, 1,3-dimethyl-2-imidazolidinone, and the like can be mixed with the above solvent.

The reaction temperature in the lithiation can be carried out from the freezing point of the solvent to the solvent dry distillation temperature.
From the stability of the resulting lithiated product, the temperature is preferably from -100 ° C to room temperature, particularly preferably from -78 ° C to -30 ° C.

Examples of the fluorinating agent in this reaction include N-fluorosulfonimides such as N-fluorobenzenesulfonimide, N-fluorotoluenesulfonimide, N-fluoromethanesulfonimide, N-fluorotrifluoromethanesulfonimide and the like. -Fluoro-2,4,6-trimethylpyridinium trifluoromethanesulfonate, N-fluoro
N-fluoropyridinium salts such as -2,4,6-trimethylpyridinium tetrafluoroborate, difluoroxenon, fluorine gas, and the like. Imides are preferred.

The reaction temperature in the fluorination can be carried out from the freezing point of the solvent to the solvent dry distillation temperature. From the reaction rate, it is preferably from -78 ° C to 60 ° C, and from the lithiation temperature to -20 ° C.
It is particularly preferable to raise the temperature to room temperature.

[0022]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Reference Example 1 5,6-Difluoro-2- (trans
Synthesis of (-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene

Embedded image 1,2-Difluoro-6- (trans
5 g of -4-propylcyclohexyl) naphthalene, 70 mg of 5% palladium-carbon (containing 50% water) and 100 ml of ethyl acetate were added, and the mixture was reacted at 15 atm of hydrogen and 120 ° C. for 8 hours. The reaction solution was filtered through celite, concentrated, and the residue was purified by column chromatography (silica gel, hexane).
Recrystallized from ethanol to give 5,6-difluoro-2- (trans
2.5 g of (-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene was obtained.

Example 1 Synthesis of 5,6,7-trifluoro-2- (trans-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene

[0025]

Embedded image In a 20 ml solution of 1 g of 5,6-difluoro-2- (trans-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene in 20 ml of tetrahydrofuran, sec-butyllithium (0.8 M hexane-cyclohexane (Mixed solution) 7 ml was added and stirred for 1 hour. 2 g of N-fluorophenylsulfonimide ((PhSO ₂ ) ₂ NF) was added, and the temperature was raised to 0 ° C. over 5 hours with stirring. After adding 10% hydrochloric acid to the reaction solution and extracting with hexane, the organic layer was washed with 10% hydrochloric acid and saturated saline, dried over anhydrous sodium sulfate, and concentrated. The residue was purified by column chromatography (silica gel, hexane) and further recrystallized from ethanol to give 5,6,7-trifluoro-2- (trans-4-propylcyclohexyl) -1,2,
0.6 g of 3,4-tetrahydronaphthalene was obtained. Melting point 52 ° C Mass m / z 310 (M +) 19F NMR (CDCl3, internal standard: hexafluorobenze
ne) -151, -151.5, -177ppm

[0026]

According to the present invention, it has been difficult to obtain until now,
A trifluorotetrahydronaphthalene derivative whose production method is complicated can be produced industrially easily and at low cost. This trifluorotetrahydronaphthalene derivative is extremely useful as a liquid crystal display material.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C07D 241/12 C07D 241/12 // C07B 61/00 300 C07B 61/00 300 F term (reference) 4C055 AA01 BA02 BA11 CA02 CA11 DA01 4H006 AA02 AC30 BA03 BA44 BA46 BE90 EA35 4H039 CA51 CD10

Claims (10)

[Claims] 1. A compound of the general formula (I) (Wherein, R is a saturated or unsaturated alkyl having 1 to 20 carbon atoms which may be substituted by one or more fluorine atoms and / or an alkoxyl group having 1 to 7 carbon atoms, and which may contain a branched chain) represents a group or an alkoxyl group, linking group X, Y is a single _{bond, -CH 2 CH 2 -, -} CH = CH -, - CH (CH 3) CH 2 -, -
CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )-, -C≡C-,-(CH ₂ ) ₄ -,-
Represents CH ₂ O— or —OCH ₂ —, wherein ring A and ring B are trans
1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2.2] octane-1,4-diyl group And a 1,4-phenylene group which may be substituted by one or two fluorine atoms, a pyridine-2,5-diyl group, a pyrimidine-2,5-
Diyl group, pyrazine-2,5-diyl group and pyridazine-3,
Represents a 6-diyl group, and n represents an integer of 0 to 2. ), Wherein the difluorotetrahydronaphthalene derivative represented by the general formula (II) is lithiated and then fluorinated. (Wherein, R is a saturated or unsaturated alkyl having 1 to 20 carbon atoms which may be substituted by one or more fluorine atoms and / or an alkoxyl group having 1 to 7 carbon atoms and which may contain a branched chain) represents a group or an alkoxyl group, linking group X, Y is a single _{bond, -CH 2 CH 2 -, -} CH = CH -, - CH (CH 3) CH 2 -, -
CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )-, -C≡C-,-(CH ₂ ) ₄ -,-
Represents CH ₂ O— or —OCH ₂ —, wherein ring A and ring B are trans
1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2.2] octane-1,4-diyl group And a 1,4-phenylene group which may be substituted by one or two fluorine atoms, a pyridine-2,5-diyl group, a pyrimidine-2,5-
Diyl group, pyrazine-2,5-diyl group and pyridazine-3,
Represents a 6-diyl group, and n represents an integer of 0 to 2. A method for producing a trifluorotetrahydronaphthalene derivative represented by the formula: 2. The method according to claim 1, wherein alkyllithium or lithium amide is used for the lithiation. 3. The method according to claim 1, wherein N-fluorosulfonimide is used as the fluorinating agent. 4. In the formulas (I) and (II), ring A and ring B are trans-1,4-cyclohexylene, trans
-Decahydronaphthalene-2,6-diyl group, trans-1,3-
Dioxane-2,5-diyl group, bicyclo [2.2.2] octane-
4. The production method according to claim 1, wherein the production method is a 1,4-diyl group or a 1,4-phenylene group. 5. In the formulas (I) and (II), ring A and ring B are trans-1,4-cyclohexylene, trans
-Decahydronaphthalene-2,6-diyl group and bicyclo
[2.2.2] Claim 1 which is an octane-1,4-diyl group
4. The production method according to any one of items 1 to 3. 6. The production method according to claim 1, wherein in the general formulas (I) and (II), the ring A and the ring B are trans-1,4-cyclohexylene groups. 7. The compound according to claim 1, wherein the linking groups X and Y in the general formulas (I) and (II) are a single bond or —CH ₂ CH ₂ —.
7. The method according to any one of items 1 to 6, above. 8. In the general formulas (I) and (II), R is 1
Claims being a saturated or unsaturated alkyl group having 1 to 20 carbon atoms which may be substituted by at least two fluorine atoms and / or an alkoxyl group having 1 to 7 carbon atoms and which may contain a branched chain. Item 8. The production method according to any one of Items 1 to 7. 9. The compound according to claim 1, wherein in the general formulas (I) and (II), R is a saturated or unsaturated alkyl group having 1 to 20 carbon atoms which may contain a branched chain. The manufacturing method as described. 10. The process according to claim 1, wherein R in Formulas (I) and (II) is a saturated or unsaturated linear alkyl group having 1 to 20 carbon atoms. Method.