JP2002003416A - Method for producing 1,2,3,4-tetrahydronaphthalene derivative - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily producing a fluorotetrahydronaphthalene derivative that has been difficult or complicated to produce so far. SOLUTION: This method comprises easily producing, from the corresponding naphthalene derivative, a fluorotetrahydronaphthalene derivative that has been difficult or complicated to produce so far. This method enables aimed high- quality materials to be produced at low cost, being highly practical as a method for producing fluorotetrahydronaphthalene derivatives including liquid crystal technical products.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a tetrahydronaphthalene derivative useful as a liquid crystal display material.

[0002]

2. Description of the Related Art Liquid crystal display elements have been used in various measuring instruments such as watches and calculators, panels for automobiles, word processors, electronic organizers, printers, computers, 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 (anti-ferroelectric 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 improved 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 is a 1,4-phenylene group (may be substituted with one or two halogen atoms, a cyano group, a methyl group, etc.) and trans-1,4 -
Cyclohexylene groups make up 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. Things are only a few.

The present inventors have proposed compounds (III) and (IV)

Embedded image And other novel fluorine-substituted tetrahydronaphthalene derivatives.
1-191670). However, since the yield in producing these compounds is hardly 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 fluorine-substituted tetrahydronaphthalene derivative is required.

[0007]

The problem to be solved by the present invention is to meet the above-mentioned objects, and therefore, the reaction step of a fluorine-substituted tetrahydronaphthalene derivative is short, the reaction yield is good, and the raw material is inexpensive. It is an object of the present invention to provide a novel production method having high reactivity and low reaction by-products.

[0008]

In order to solve the above-mentioned problems, the present invention has found a method for producing a fluorine-substituted tetrahydronaphthalene derivative described below.

Invention 1 General formula (I)

[Formula 4] (In the formula, R ¹ represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and this group is unsubstituted, or at least one fluorine atom or has an alkyl group having 1 to 5 carbon atoms, and as if one or more CH ₂ groups are O atoms each independently present in the group not linked directly to one another -O- , -S-, and may be optically active or racemic.
1,4-cyclohexylene group (one CH ₂ present in this group
Group or adjacent two or more CH ₂ groups not may be replaced by -O- and or -S-), one or two fluorine atoms may be substituted 1,4-phenylene group, Trans-1,3-dioxane-2,5-diyl group, trans-decahydronaphthalene-2,6-diyl group or bicyclo [2.2.2] octane-1,4-diyl group, having 1 to 3 carbon atoms May be substituted with an alkyl group or a fluorine atom. L 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 )-,-(CH ₂ ) ₄ -or -C≡C-
n represents 0, 1 or 2, X ¹ , X ² and X ³ each independently represent a fluorine atom or a hydrogen atom, Z represents the same meaning as R ¹ , or a hydrogen atom, a fluorine atom, It represents a trifluoromethoxy group or a difluoromethoxy group, and a plurality of groups in ring A or L may be the same or different. However, when X ¹ represents a fluorine atom, at least one of X ^{2 and} X ³ represents a fluorine atom. The naphthalene derivative represented by the general formula (II)

[Formula 5] (Wherein R ² represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms,
This group is unsubstituted or has at least one fluorine atom or an alkyl group having 1 to 5 carbon atoms as a substituent, and one or two or more CHs present in these groups. _{The two} groups may be independently replaced by -O- or -S- assuming that O atoms are not directly bonded to each other, and may be optically active or racemic. Ring A is trans-1,4-cyclohexylene group, 1,4-phenylene group optionally substituted by one or two fluorine atoms, trans-decahydronaphthalene-2,6-diyl group, trans-1, 3-dioxane-2,5-diyl group or bicyclo
[2.2.2] represents an octane-1,4-diyl group, M is a single bond, -CH
₂ CH _2- , -CH (CH ₃ ) CH _2- , -CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )
- or - (CH _{2) 4} - represents either Z are as defined R ^2,
Alternatively, represents a hydrogen atom, a fluorine atom, a trifluoromethoxy group or a difluoromethoxy group, n, X ¹ , X ² and X
³ has the same meaning as in formula (I), and a plurality of groups in ring A or M may be the same or different. ) 1,
A method for producing a 2,3,4-tetrahydronaphthalene derivative.

Invention 2 The process according to Invention 1, wherein the reduction uses at least one hydrogenation reduction catalyst selected from the metals of Rh, Ru, Pt, Pd, Re, Ir or Os or a metal compound thereof. Method.

Invention 3 The method according to Invention 1, wherein the reduction uses a metal of Pd or a metal compound thereof.

Invention 4 The process according to any one of Inventions 1 to 3, wherein the reduction is carried out under a hydrogen stream to 40 atm of hydrogen.

Invention 5 The process according to any one of Inventions 1 to 4, wherein the reduction is carried out at room temperature to 200 ° C.

Invention 6 In the general formulas (I) and (II), the ring A
Is trans-1,4-cyclohexylene, trans-decahydronaphthalene-2,6-diyl, trans-1,3-dioxane-2,5-diyl or bicyclo [2.2.2] octane-1,4 -
The production method according to any one of Inventions 1 to 5, which is a diyl group.

Invention 7 The process according to any one of Inventions 1 to 6, wherein L and M in formulas (I) and (II) are single bonds.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the present invention will be described below. In invention 1, R ¹ is preferably an alkyl group having 1 to 10 carbon atoms which may be substituted, an alkoxyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and an unsubstituted linear carbon number. An alkyl group having 1 to 8 carbon atoms, a linear alkoxyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to 8 carbon atoms is more preferable, and an unsubstituted linear alkyl group having 1 to 6 carbon atoms is particularly preferable. Ring A is a trans-1,4-cyclohexylene group, trans-decahydronaphthalene-2,6-diyl group, trans-1,3-dioxane-2,5-diyl group, bicyclo [2.2.
2] an octane-1,4-diyl group or a 1,4-phenylene group which may be substituted by one or two fluorine atoms, preferably a trans-1,4-cyclohexylene group, a trans-decahydronaphthalene-2 , 6-diyl group, trans-1,3-dioxane-2,5-diyl group or bicyclo [2.2.2] octane-
A 1,4-diyl group is more preferred. L is a single bond, -CH ₂ CH ₂ -,-
CH = CH -, - CH ( CH 3) CH 2 -, - CH 2 CH (CH 3) -, - CH (CH 3) CH (C
H ₃ ) —, — (CH ₂ ) ₄ — or —C≡C—, preferably a single bond or —CH ₂ CH ₂ —, and particularly preferably a single bond. n is 0,
Represents 1 or 2, preferably 1 or 2. X ¹ , X ² and X ³ each independently represent a fluorine atom or a hydrogen atom, but it is preferable that at least one represents a fluorine atom, and when X ¹ and X ² are a fluorine atom or X ² and X ³ More preferably, it represents a fluorine atom. R ² is an optionally substituted alkyl group having 1 to 10 carbon atoms or 1 carbon atom
~ 10 alkoxyl groups are preferable, unsubstituted linear alkyl groups having 1 to 8 carbon atoms or alkoxyl groups having 1 to 8 linear carbon atoms are more preferable, and unsubstituted linear carbon atoms having 1 to 6 carbon atoms. alkyl group is particularly preferred, M is a single _{bond, -CH 2 CH 2 -, -} CH
(CH ₃ ) CH _2- , -CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )-or-
(CH ₂ ) ₄ — is preferably a single bond or —CH ₂ CH ₂ —, and more preferably a single bond.

As the hydrogenation reduction catalyst, Rh, Ru, Pt, P
d, Ir or Os metal or a metal compound thereof. These metals and metal compounds may be used alone or in combination of two or more. For example, Pd
Specific examples of metals and compounds thereof include palladium carbon, palladium powder, palladium oxide, palladium chloride, palladium bromide, palladium iodide, tetraamminepalladium chloride, tetraamminepalladium nitrate, palladium salts such as tetraamminepalladium acetate, and tetrakis. Palladium complexes such as (triphenylphosphine) palladium and bis (acetylacetonato) palladium are mentioned. Also, instead of the above Pd, R
The same applies to the metals of h, Ru, Pt, Re, Ir, and Os and / or their metal compounds. These metals and metal compounds may be used alone or in combination of two or more. Further, silica gel, alumina or the like may be added to or supported on these. Among them, a metal of Pd or a metal compound thereof is preferable.

The reaction is carried out under a hydrogen atmosphere from a hydrogen atmosphere at 200 atm (1
9.6 MPa), but preferably from hydrogen atmosphere to 100 atm (9.8 MPa) of hydrogen, and from the hydrogen atmosphere to 40 atm (3.9 MPa) from hydrogen to simplify the use of the reaction vessel.
Particularly preferred is below.

Various solvents can be used in this reaction. As the reaction solvent, alcohols, organic acids such as acetic acid, ethers, esters, saturated hydrocarbons, benzenes, amides and the like can be used alone or as a mixture, but alcohols, organic acids and A mixed solvent containing them is preferred. This reaction is 300
The reaction can be carried out at a temperature of up to 0 ° C, but 0 ° C to 200 ° C is preferred.

[0020]

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

[Formula 6] In a stainless steel autoclave, 6- (trans-4-propylcyclohexyl) -1,2,3-trifluoronaphthalene (10
g), 5% palladium on carbon (50% water content) (1 g) and ethanol
(100 ml) and stirred at 80 ° C. for 14 hours under 5 atm (0.49 MPa) of hydrogen. The reaction solution was filtered through celite, and the filtrate was concentrated. The residue was purified by silica gel chromatography (hexane) to give 2- (trans-4-propylcyclohexyl) -5,
6,7-trifluoro-1,2,3,4-tetrahydronaphthalene (9.
3 g, 95% purity). Further recrystallization from ethanol, 2- (trans-4-propylcyclohexyl) -5,6,7-trifluoro-1,2,3,4-tetrahydronaphthalene (5.6 g,
Purity> 99%).

Example 2 7,8-Difluoro-6-ethyl-2-
Production of (trans-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene

Embedded image Under the same conditions as in Example 1, 1,2-difluoro-3-ethyl-7-
7,8-Difluoro-6-ethyl-2- (trans-4-propylcyclohexyl) -1,2,3,4-tetrahydronaphthalene was produced using trans-4-propylcyclohexyl) -naphthalene.

[0022]

According to the production method of the present invention, it has become possible to easily produce a tetrahydronaphthalene derivative which was conventionally difficult and complicated. By using this method, a high-quality material can be manufactured at low cost, and it is very practical as a method for manufacturing a tetrahydronaphthalene derivative including a liquid crystal material.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Haruyoshi Takatsu 3-6-27 Nakahara, Higashiyamato-shi, Tokyo F-term (reference) 4H006 AA02 AC11 BA16 BA22 BA24 BA25 BA26 BC10 BC11 BE20 4H039 CA41 CB10

Claims (7)

[Claims] [Claim 1] General formula (I) (In the formula, R ¹ represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms or an alkenyl group having 2 to 15 carbon atoms, and this group is unsubstituted, or at least one fluorine atom or has an alkyl group having 1 to 5 carbon atoms, and as if one or more CH ₂ groups are O atoms each independently present in the group not linked directly to one another -O- , -S-, and may be optically active or racemic.
1,4-cyclohexylene group (one CH ₂ present in this group
Group or adjacent two or more CH ₂ groups not may be replaced by -O- and or -S-), one or two fluorine atoms may be substituted 1,4-phenylene group, Trans-1,3-dioxane-2,5-diyl group, trans-decahydronaphthalene-2,6-diyl group or bicyclo [2.2.2] octane-1,4-diyl group, having 1 to 3 carbon atoms May be substituted with an alkyl group or a fluorine atom. L 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 )-,-(CH ₂ ) ₄ -or -C≡C-
n represents 0, 1 or 2, X ¹ , X ² and X ³ each independently represent a fluorine atom or a hydrogen atom, Z represents the same meaning as R ¹ , or a hydrogen atom, a fluorine atom, It represents a trifluoromethoxy group or a difluoromethoxy group, and a plurality of groups in ring A or L may be the same or different. However, when X ¹ represents a fluorine atom, at least one of X ^{2 and} X ³ represents a fluorine atom. The naphthalene derivative represented by the general formula (II) is hydrogenated and reduced. (Wherein R ² represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms,
This group is unsubstituted or has at least one fluorine atom or an alkyl group having 1 to 5 carbon atoms as a substituent, and one or two or more CHs present in these groups. _{The two} groups may be independently replaced by -O- or -S- assuming that O atoms are not directly bonded to each other, and may be optically active or racemic. Ring A is trans-1,4-cyclohexylene group, 1,4-phenylene group optionally substituted by one or two fluorine atoms, trans-decahydronaphthalene-2,6-diyl group, trans-1, 3-dioxane-2,5-diyl group or bicyclo
[2.2.2] represents an octane-1,4-diyl group, M is a single bond, -CH
₂ CH _2- , -CH (CH ₃ ) CH _2- , -CH ₂ CH (CH ₃ )-, -CH (CH ₃ ) CH (CH ₃ )
- or - (CH _{2) 4} - represents either Z are as defined R ^2,
Alternatively, represents a hydrogen atom, a fluorine atom, a trifluoromethoxy group or a difluoromethoxy group, n, X ¹ , X ² and X
³ has the same meaning as in formula (I), and a plurality of groups in ring A or M may be the same or different. ) 1,
A production method for producing a 2,3,4-tetrahydronaphthalene derivative. 2. The method according to claim 1, wherein the reduction is Rh, Ru, Pt, Pd, Re, Ir or Os.
2. The production method according to claim 1, wherein at least one kind of hydrogenation reduction catalyst selected from the above metals or metal compounds thereof is used. 3. The production method according to claim 1, wherein the reduction uses a metal of Pd or a metal compound thereof. 4. The production method according to claim 1, wherein the reduction is carried out under a hydrogen gas flow to a pressure of 40 atm of hydrogen. 5. The method according to claim 1, wherein the reduction is carried out at room temperature to 200 ° C. 6. In formulas (I) and (II), ring A is trans-1,4-cyclohexylene, trans-decahydronaphthalene-2,6-diyl, trans-1,3-dioxane-2. ,Five
The method according to any one of claims 1 to 5, which is a -diyl group or a bicyclo [2.2.2] octane-1,4-diyl group. 7. The method according to claim 1, wherein L and M in formulas (I) and (II) are single bonds.