JP2727688B2 - Optically active benzyl derivatives and their preparation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a liquid crystal compound, particularly to a liquid crystal compound useful as an intermediate of a liquid crystal compound having excellent image display responsiveness, and a method for producing the same.

<Conventional Technology> Various studies have been made on searching for a liquid crystal compound, particularly a liquid crystal compound having excellent responsiveness in image display.

The Chemical Society of Japan (The
Chemical Society of Japan: Chemistry Letter (C
HEMISTRY LETTERS) pp.1657-1660, (1981) has the following general formula Are known, but this compound is not suitable for the object of the present invention.

<Problems to be Solved by the Invention> The present inventors have made intensive studies to find a liquid crystal compound, particularly a liquid crystal compound having excellent responsiveness for image display or an intermediate thereof, and finally arrived at the present invention. It is.

<Means for Solving the Problems> The present invention provides a compound represented by the general formula (I): (Wherein, R ¹ represents an alkyl group or an alkyloxyalkyl group which may be substituted by a halogen atom having 1 to 20 carbon atoms, and X represents a halogen atom, an —OH group, or an —OSO ₂ R ² group. And R ² represents a lower alkyl group, a trifluoromethyl group or a phenyl group which may be substituted, l is 1 or 2, and * represents an asymmetric carbon atom. An active benzyl derivative and a method for producing the same.

The optically active benzyl derivative represented by the above general formula (I) of the present invention has the general formula (II) (Wherein, R ³ represents a hydrogen atom or an alkyl group, and R ¹ ,
l and * have the same meanings as described above), by reducing an optically active ester represented by the following general formula (I) wherein X is an -OH group in the general formula (I).
-A) (Wherein, R ¹ , l, and * have the same meanings as described above).

Next, the optically active benzyl alcohol derivative (I-
By halogenating a), the following general formula (1-b) wherein X is a halogen atom in the above general formula (Wherein X ¹ represents a halogen atom, and R ¹ , l and * have the same meanings as described above).
The optically active benzyl alcohol derivative (Ia) is subjected to sulfonic acid esterification to give the above-mentioned general formula (I)
Formula X is -OSO ₂ R ² in (1-c) (Wherein, X ² represents an -OSO ₂ R ² group. Where R ² is a lower alkyl group, .R ¹ showing a trifluoromethyl group or an optionally substituted phenyl group, l and * mark the Having the same meaning as in the above).

For the reduction of the optically active ester represented by the general formula (II), a known reagent and a known method capable of reducing a carboxylic acid or an ester group are applied. Specifically, lithium aluminum hydride is used. , Lithium borohydride, sodium borohydride-Lewis acid and the like are preferably used.

The amount of the reducing agent to be used must be at least one equivalent or more based on the optically active ester (II), and is usually 1 to 10 equivalents.
The range of equivalents.

This reduction reaction is usually performed in a solvent inert to the reaction. Examples of such a solvent include tetrahydrofuran, dioxane, ethyl ether, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, toluene, benzene, chloroform, and dichloromethane. Or a mixture of ethers, halogenated hydrocarbons or alcohols.

The reaction temperature is usually in the range of -30C to 100C, preferably in the range of -20C to 90C. The reaction time is not particularly limited.

From the reaction mixture thus obtained, an optically active benzyl alcohol derivative (Ia) can be obtained in good yield by operations such as liquid separation, concentration, distillation, and crystallization. In order to obtain the active benzyl derivatives (Ib) and (Ic), it is not always necessary to isolate the optically active benzyl alcohol derivative, and the reaction mixture may proceed to the next step.

The reaction for obtaining the compound represented by the general formula (Ib) from the optically active benzyl alcohol derivative (Ia) is performed by reacting the optically active benzyl alcohol derivative (Ia) with a halogenating agent. .

This reaction is usually carried out in the presence of a solvent. As the halogenating agent, for example, in the case of chlorination, hydrogen chloride, thionyl chloride, phosphorus trichloride, phosphorus pentachloride, boron trichloride, triphenylphosphine tetrachloride Carbon and the like, and in the case of bromination, hydrogen bromide (acid), thionyl bromide, phosphorus tribromide, boron tribromide, triphenylphosphine dibromide, triphenylphosphine-4 carbon bromide and the like are used. .

The amount of the halogenating agent to be used is required to be 1 equivalent or more times the amount of the optically active benzyl alcohol derivative (Ia), and the upper limit is not particularly limited, but is preferably 1.1 to 4 equivalents.

This halogenation reaction is usually performed in the presence of a solvent inert to the reaction. Examples of the solvent used include ethers such as tetrahydrofuran, dioxane, ethyl ether, toluene, benzene, hexane, chloroform, dichloromethane, and dichloromethane. Alternatively, a single or a mixture of halogenated hydrocarbons or the like is used.

In the halogenation reaction, the addition of a catalyst may be effective.Examples of the catalyst used include pyridine, 4-dimethylaminopyridine, N, N'-dimethylformamide and the like. To the optically active benzyl alcohol derivative (Ia)
It is in the range of 0.1 to 5 mol%.

The reaction temperature is usually in the range of -20 ° C to 150 ° C, preferably in the range of -20 ° C to 100 ° C.

 The reaction time is not particularly limited.

In this manner, the optically active benzyl derivative (Ib) can be obtained from the obtained reaction mixture in a high yield by operations such as liquid separation, concentration, distillation, and crystallization.

Next, an optically active benzyl alcohol derivative (I-
In the reaction for obtaining the optically active benzyl derivative represented by the general formula (Ic) from a), the optically active benzyl alcohol derivative (Ia) is converted into a compound of the general formula (III) Y—SO ₂ R ² (III) ( Wherein Y is a halogen atom or Wherein R ⁴ represents a lower alkyl group, a trifluoromethyl group or an optionally substituted phenyl group, and R ² has the above-mentioned meaning. The reaction is usually carried out with a sulfonic esterifying agent represented by the formula (1) in the presence of a solvent, preferably in the presence of a catalyst.

As a solvent used in this reaction, for example, tetrahydrofuran, ethyl ether, acetone,
Inactive in the reaction of aliphatic or aromatic ethers such as methyl ethyl ketone, toluene, benzene, chlorobenzene, dichloromethane, dichloroethane, chloroform, carbon tetrachloride, dimethylformamide, hexane, ketones, halogenated hydrocarbons, etc. Solvents alone or in mixtures can be mentioned. The amount used is not particularly limited.

In the sulfonic acid esterification reaction, as the sulfonic acid esterifying agent represented by the general formula (III),
Specific examples include paratoluenesulfonyl chloride, benzenesulfonyl chloride, ethanesulfonyl chloride, methanesulfonyl chloride, parabromobenzenesulfonyl chloride, trifluoromethanesulfonic anhydride and the like. The amount used is required to be at least 1 equivalent times the optically active benzyl alcohol derivative (Ia), and the upper limit is not particularly limited, but is preferably 1.1 to 4 equivalent times.

In the sulfonic acid esterification, a catalyst can be used. Examples of the catalyst include dimethylaminopyridine, triethylamine, pyridine, tri-n
-Butylamine, picoline, collidine, imidazole,
Sodium carbonate, potassium carbonate, sodium bicarbonate,
1,8-diazabicyclo [5,4,0] 7-undecene (DBU)
And other organic or inorganic basic properties.

In using such a catalyst, for example, when a sulfonyl halide is used as a raw material, pyridine, triethylamine, picoline and the like are particularly preferably used.

The amount of the catalyst used depends on the combination of the sulfonic esterifying agent represented by the general formula (III) and the catalyst used, and is not necessarily specified. For example, when a sulfonyl halide is used, the amount of the catalyst is based on the sulfonyl halide. At least 1 equivalent times.

The reaction temperature is usually -30C to 150C, preferably -20C to 100C.

The reaction time is not particularly limited, and the point at which the raw materials disappear can be the end point of the reaction.

After completion of the reaction, usual separation means such as extraction, liquid separation,
By an operation such as concentration, the general formula (Ic) is obtained from the reaction mixture.
Can be obtained in good yield and can be purified by column chromatography or the like, if necessary.

The compounds represented by the general formula (I) thus obtained are exemplified below.

4- (1-alkyloxyethyl) benzyl alcohol 4- (1-alkyloxyethyl) benzyl chloride 4- (1-alkyloxyethyl) benzyl bromide 4- (1-alkyloxyethyl) benzyl p-toluenesulfonate 4- ( 1-alkyloxyethyl) benzylbenzenesulfonate 4- (1-alkyloxyethyl) benzylmethanesulfonate 4- (1-alkyloxyethyl) benzyltrifluoromethylsulfonate 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl alcohol 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl chloride 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl bromide 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl p-toluenesulfonate 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl benzenesulfonate 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl methanesulfonate 4- {4 '-(1-alkyloxyethyl) phenyl}
Benzyl trifluoromethylsulfonate In the examples, alkyl is a substituent R ¹ in the general formula (I) and may be an alkyl group which may be substituted with a halogen atom having 1 to 20 carbon atoms as shown below. Or an alkyloxyalkyl group.

Methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, methoxymethyl, methoxyethyl, methoxypropyl, methoxy Butyl, methoxypentyl, methoxyhexyl, methoxyheptyl, methoxyoctyl, methoxynonyl, methoxydecyl, ethoxymethyl, ethoxyethyl, ethoxypropyl, ethoxybutyl, ethoxypentyl, ethoxyhexyl, ethoxyheptyl, ethoxyoctyl, ethoxynonyl, ethoxydecyl, Propoxymethyl, propoxyethyl, propoxypropyl, propoxybutyl, propoxypentyl, propoxyhex Le, propoxy heptyl, propoxy octyl propoxy nonyl, propoxy decyl,
Butoxymethyl, butoxyethyl, butoxypropyl,
Butoxybutyl, butoxypentyl, butoxyhexyl, butoxyheptyl, butoxyoctyl, butoxynonyl, butoxydecyl, pentyloxymethyl, pentyloxyethyl, pentyloxypropyl, pentyloxybutyl, pentyloxypentyl, pentyloxyhexyl, pentyloxyoctyl, pentyl Oxydecyl, hexyloxymethyl, hexyloxyethyl,
Hexyloxypropyl, hexyloxybutyl, hexyloxypentyl, hexyloxyhexyl, hexyloxyoctyl, hexyloxynonylhexyloxydecyl, heptyloxymethyl, heptyloxyethyl, heptyloxypropylheptyloxybutyl, heptyloxypentyloctyloxymethyl, octyl Oxyethyl, octyloxypropyl, decyloxymethyl, decyloxyethyl, decyloxypropyl,
1-methylethyl, 1-methylpropyl, 1-methylbutyl, 1-methylpentyl, 1-methylhexyl, 1-
Methylheptyl, 1-methyloctyl 2-methylethyl, 2-methylbutyl, 2,3-dimethylbutyl, 2,3,3-
Trimethylbutyl, 2-methylpentyl, 3-methylpentyl, 2,3-dimethylpentyl, 2,4-dimethylpentyl, 2,3,3,4-tetramethylpentyl, 2-methylhexyl, 3-methylhexyl, -Methylhexyl, 2,5
-Dimethylhexyl, 2-methylheptyl, 2-methyloctyl, 2-trihalomethylpentyl, 2-trihalomethylhexyl, 2-trihalomethylheptyl, 2-haloethyl, 2-halopropyl, 3-halopropyl, 3-
Halo-2-methylpropyl, 2,3-dihalopropyl, 2
-Halobutyl, 3-halobutyl, 4-halobutyl, 2,3
-Dihalobutyl, 2,4-dihalobutyl, 3,4-dihalobutyl, 2-halo-3-methylbutyl, 2-halo-3,3-dimethylbutyl, 2-halopentyl, 3-halopentyl,
4-halopentyl, 5-halopentyl, 2,4-dihalopentyl, 2,5-dihalopentyl, 2-halo-3-methylpentyl, 2-halo-4-methylpentyl, 2-halo-
3-monohalomethyl-4-methylpentyl, 2-halohexyl, 3-halohexyl, 4-halohexyl, 5-halohexyl, 6-halohexyl, 2-haloheptyl, 2
-Halooctyl (however, halo in the above alkyl group represents fluorine, chlorine, bromine or iodine).

The optically active esters represented by the general formula (II) used as a raw material can be synthesized, for example, by the following route.

(In the formula, R ³ and l have the above-mentioned meanings, and R ⁵ represents a lower alkyl group.) <Effect of the Invention> Thus, according to the method of the present invention, a novel compound represented by the general formula (I) The optically active benzyl derivative shown can be efficiently produced, and the compound of the present invention (I)
Is useful not only as a material for liquid crystals but also as an intermediate for agricultural chemicals, medicines and the like.

For example, the optically active benzyl derivative represented by the general formula (I) of the present invention can be easily led to the optically active liquid crystal compound represented by the general formula (IV) by the following method, for example.

(Wherein, X, R ¹ and l have the above-mentioned meanings) (In the formula, Ar represents an aromatic group, R ⁶ represents an alkyl group or an alkoxyl group, etc.) <Examples> Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 In a four-necked flask equipped with a stirrer and a thermometer, 400 ml of anhydrous ethyl ether was added to 5.7 g of lithium aluminum hydride.
And a solution of 26.4 g (0.1 mol) of methyl (+)-4- (1-hexyloxyethyl) benzoate in 100 ml of ethyl ether is added dropwise at 20 to 30 ° C. After completion of the dropwise addition, the mixture was stirred at about 30 ° C. for 2 hours, then excessive lithium aluminum hydride was decomposed with a small amount of ethanol, and 300 ml of 10% aqueous ammonium chloride was added. The obtained organic layer was washed with brine, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain 23.2 g of liquid (+)-4- (1-hexyloxyethyl) benzyl alcohol. (98% yield). This infrared absorption spectrum (Nujol method)
Shown in the figure.

Method A: 2.36 g (10 mmol) of (+)-4- (1-hexyloxyethyl) benzyl alcohol obtained above was dissolved in 5 ml of toluene, and 2 ml of thionyl chloride was added.
Several drops of pyridine were added at 2020 ° C., and the mixture was stirred at the same temperature for 4 hours. After completion of the reaction, the reaction mixture was poured into 50 g of ice, extracted with 100 ml of toluene, and the organic layer was thoroughly washed with water, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure to obtain a light yellow liquid (+)-4-. 2.5 g of (1-hexyloxyethyl) benzyl chloride (98% yield) ▲ [α] ²⁰ _D ▼ = + 59.5 °
(CHCl ₃ , c = 1) was obtained.

Method B: 2.36 g (10 mmol) of (+)-4- (1-hexyloxyethyl) benzyl alcohol obtained above was dissolved in 10 ml of pyridine, and 1.2 g (11 mmol) of methanesulfonyl chloride was added at 10 ° C. or lower. And stirred at the same temperature for 4 hours. After completion of the reaction, the mixture was poured into 50 g of ice and 50 ml of 6N hydrochloric acid, and extracted with 100 ml of ether.The organic layer was sufficiently washed with 1N hydrochloric acid and subsequently with water, dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. 3.0 g of oily (+)-4- (1-hexyloxyethyl) benzylmethanesulfonate (yield 95
%) ▲ [α] ²⁰ _D ▼ = + 51.8 ° (CHCl ₃ , c = 1) was obtained.

Example 2 In a four-necked flask equipped with a stirrer and a thermometer, (+)-
18.0 g (0.1 mol) of 4- (1-methoxyethyl) benzoic acid
And 100 ml of toluene at room temperature.
90 ml (0.3 mol) of a toluene solution (3.4 M) of sodium methoxyethoxy) aluminum is added dropwise, and the mixture is stirred at room temperature for one day. After completion of the reaction, the excess reducing agent was decomposed with ethanol, poured out into 400 ml of 4N hydrochloric acid, extracted, and the organic layer was thoroughly washed with water and dried over anhydrous magnesium sulfate. The solvent was distilled off under reduced pressure to obtain (+)-4- (1
-Methoxyethyl) benzyl alcohol 15.8 g (yield 95
%) ▲ [α] ²⁰ _D ▼ = + 72.2 ° (CHCl ₃ , c = 1) was obtained.

Method C: 1.7 g (10 mmol) of (+)-4- (1-methoxyethoxy) benzyl alcohol obtained above in toluene
The mixture was dissolved in 20 ml, and at 30 to 40 ° C., 2.7 g (10 mmol) of phosphorus tribromide was added, followed by reaction at room temperature for 2 hours and at 50 ° C. for 2 hours.
After the completion of the reaction, the mixture is poured into 50 g of ice and extracted with 100 ml of toluene.
After thoroughly washing with water, the extract was dried over anhydrous magnesium sulfate, and the solvent was distilled off under reduced pressure. The obtained residue was purified by silica gel column chromatography (eluent; toluene),
(+)-4- (1-methoxyethyl) benzyl bromide
1.49 g (65% yield) ▲ [α] ²⁰ _D ▼ = + 68.1 ° (CHCl
₃ , c = 1).

Example 3 In Example 1, instead of methyl (+)-4- (1-hexyloxyethyl) benzoate, (+)-4- (1-
Hexyloxyethyl) -4'-biphenylcarboxylate The reaction and post-treatment were conducted in the same manner as in Example 1 except that 34.0 g (0.1 mol) of methyl was used to obtain (+)-4- (1-hexyloxyethyl) -4. '-Hydroxymethyl biphenyl 30.9 g
(Yield 99%) ▲ [α] ²⁰ _D ▼ = + 65.6 ° (CHCl ₃ , c =
1), (n ²⁰ _D ) = 1.5578 was obtained.

(+)-4- (1-hexyloxyethyl) obtained above
3.12 g of -4'-hydroxymethylbiphenyl was reacted and worked up according to Method A of Example 1 to give (+)-4- (1-
(Hexyloxyethyl) -4'-chloromethylbiphenyl 3.2 g (96% yield) ▲ [α] ²⁰ _D ▼ = + 60.1 ° (CHC
l ₃ , c = 1).

Examples 4 to 11 Example 1 was repeated except that the starting material (II) (0.1 mol) shown in Table 1 was used in place of methyl (+)-4- (1-hexyloxyethyl) benzoate. The reaction and post-treatment were carried out according to the procedures described in Table 1 to obtain the alcohol derivative shown in (Ia) of Table 1.

The alcohol derivative obtained here was reacted and post-treated in accordance with Method A or Method B of Example 1 or Method C of Example 2;
(I) was obtained.

[Brief description of the drawings]

FIG. 1 is an infrared absorption spectrum (Nujol method) of (+)-4- (1-hexyloxyethyl) benzyl alcohol obtained in Example 1.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location C07C 309/65 7419-4H C07C 309/65 309/73 7419-4H 309/73 // C07M 7: 00 (72) Inventor Masayoshi Minai 3-1-1, Kasuganaka, Konohana-ku, Osaka-shi, Japan Sumitomo Chemical Industries, Ltd. (56) References JP-A-2-304040 (JP, A)

Claims (6)

(57) [Claims] 1. The compound of the general formula (I) (Wherein, R ¹ represents an alkyl group or an alkyloxyalkyl group which may be substituted by a halogen atom having 1 to 20 carbon atoms, and X represents a halogen atom, an —OH group, or an —OSO ₂ R ² group. And R ² represents a lower alkyl group, a trifluoromethyl group or a phenyl group which may be substituted, l is 1 or 2, and * represents an asymmetric carbon atom. Active benzyl derivative. 2. A compound of the general formula (II) (In the formula, R ¹ represents an alkyl group or an alkyloxyalkyl group which may be substituted with a halogen atom having 1 to 20 carbon atoms, R ³ represents a hydrogen atom or an alkyl group, and 1 is 1 or 2. * Indicates that the compound is an asymmetric carbon atom). An optically active ester represented by the general formula (Ia): (Wherein, R ¹ , 1 and * have the same meanings as described above). 3. A compound of the formula (Ia) (Wherein, R ¹ represents an alkyl group or an alkyloxyalkyl group which may be substituted by a halogen atom having 1 to 20 carbon atoms, 1 represents 1 or 2, and * represents an asymmetric carbon atom. Wherein the optically active benzyl alcohol derivative represented by the general formula (Ib) is halogenated with a halogenating agent. (Wherein X ¹ represents a halogen atom, and R ¹ , l and * have the same meanings as described above). 4. A compound of the general formula (II) (Wherein, R ¹ represents an alkyl group or an alkyloxyalkyl group which may be substituted by a halogen atom having 1 to 20 carbon atoms, 1 represents 1 or 2, and * represents an asymmetric carbon atom. Wherein the optically active benzyl alcohol derivative represented by the formula is sulfonated with a sulfonating agent. (Wherein, X ² represents an -OSO ₂ R ² group. Where R ² is a lower alkyl group, .R ¹ showing a trifluoromethyl group or an optionally substituted phenyl group, l and * mark the Having the same meaning as described above). 5. The optically active benzyl derivative according to claim 1, wherein 1 is 1 in the general formula (I). 6. The optically active benzyl derivative according to claim 1, wherein 1 is 2 in the general formula (I).