LIQUID CRYSTAL COMPOUNDS AND INTERMEDIATES THEREOF

Abstract: A liquid crystal compound of the formula: wherein m and n are independently integers of 1 to 22; k and ℓ are independently integers of 1 or 2; and C* is an asymmetric carbon atom, is chemically stable and can be applied to liquid crystal display devices operable at room temperature.

Description: This invention relates to a liquid crystal compound and an intermediate thereof. In a by now highly information-oriented society, innovations of information display techniques as well as innovations of information processing, memory and transmission techniques are inevitable. Liquid crystal display devices have been used as digital displays in devices such as hand-held calculators, watches, etc., since they have advantages that low voltage driving (several volts to several tens of volts) is possible, electric power consumed is small (several µW/cm² to several tens of µW/cm²), and hence they are excellent in saving energy. Also they can be made thin and light-weight; they hardly fatigue eyes due to their non-emissive character and they are very economical. Further, they have recently been applied as flat displays for animations such as televisions in combination with active matrix driving circuits such as TFT (thin film transistor). Most of such liquid crystal display devices now practically used are of twisted nematic (TN) display mode, which has a defect in that the response speed is as slow as several tens of msec. due to revolution in a plane including a molecular axis by static forces generated by application of a voltage. Therefore, liquid crystals excellent in high speed response properties have been desired. In order to respond to such a demand, R.B. Meyer et al planned and synthesized p-decyloxybenzylidene p'-amino 2-methyl butyl cinnamate (hereinafter referred to as "DOBAMBC") having an asymmetric carbon atom, and found that DOBAMBC shows a chiral smectic C phase and the phase is a ferroelectric liquid crystalline phase [R.B. Meyer et al; J. de physique 36 , L-69 (1975)]. The response properties of ferroelectric liquid crystals by an electric field E depend on precession for maintaining the tilt angle constant by spontaneous polarization Ps. The driving force PsE is remarkably great compared with a method for applying dielectric anisotropy in nematic liquid crystals. When a ferroelectric liquid crystal is sandwiched between a pair of electrodes having a gap thinner than the helical pitch after being subjected to an orientation treatment, there is formed a molecular configuration state corresponding to a smectic C structure wherein the helical structure disappears. When a d.c. electric field is applied in this case, it is found that bistable states are formed depending on plus and minus of the electric field. By applying this memory effect, it is not necessary to use active matrix driving, and display by a simple matrix becomes possible, which results in making it possible to produce economically liquid crystal display devices with high speed response. In practice, high speed response is confirmed by sandwiching a ferroelectric liquid crystal in a very thin cell [N.A. Clark, and S.T. Lagerwall: Appl. Phys. Lett., 36 , 899 (1980)]. But DOBAMBC has defects in that its operation temperature is high (Sc* phase temperature : 75 to 95°C), and stability is not sufficient because of hydrolysis. On the other hand, European Patent Publication Nos. 0110299 and 0136725 disclose compounds of the formula: wherein R * is an optcally active alkyl group containing an asymmetric carbon atom, said compounds being excellent in stability due to having no azomethine group unlike DOBAMBC. But compounds having a hydrocarbon group as a side chain (which is optically active) generally have a higher liquid crystal phase temperature than those having an ether linkage in the side chain. The compound obtained from lactic acid as disclosed in European Patent Publication No. 0175591 has an ether linkage outside of an asymmetric carbon atom and is resistant to moisture, but is not sufficiently large in spontaneous polarization since the asymmetric carbon atom is far from an aromatic ring. SUMMARY OF THE INVENTION It is an object of this invention to provide a liquid crystal compound which is stable chemically and shows a liquid crystal phase at near room temperature and higher than room temperature; an intermediate thereof, and a process for producing the same. This invention provides a liquid crystal compound of the formula: wherein m is an integer of 1 to 22; n is an integer of 1 to 22; k and ℓ are independently an integer of 1 or 2; and C * is an asymmetric carbon atom. This invention also provides intermediates for synthesizing a liquid crystal compound and represented by the formulae: and wherein n is an integer of 1 to 22; and C * is an asymmetric carbon atom. DESCRIPTION OF THE PREFERRED EMBODIMENTS A molecular structure of ferroelectric liquid crystals comprises terminal flexible portions, a core portion and a chiral carbon portion. The liquid crystal compound of the present invention is characterized by showing a ferroelectric phase at near room temperature or higher and having a large spontaneous polarization due to having an ester structure at the core portion. Heretofore, as the core portion, there have been used a biphenyl, aromatic ester, heterocyclic, or polycyclic moiety. Further, the chiral carbon portion has been obtained by using amyl alcohol, lactic acid, an amino acid as a starting material. But there have not been known liquid crystal compounds having an aromatic ester structure as the core portion, the 1-alkoxy-2-propoxy unit as a chiral portion, which is obtained from ethyl lactate as claimed in the present invention. By taking such a special structure, the liquid crystal compounds of the present invention are chemically stable, and have a ferroelectric phase at near room temperature and higher than room temperature. Further, even if compounds do not show a ferroelectric phase near room temperature, there can be obtained a liquid crystal composition showing a ferroelectric phase near room temperature by mixing such compounds with one or more other liquid crystal compounds showing, for example, a smectic C phase or a chiral smectic C phase. The liquid crystal compound of the present invention is represented by the formula: wherein k is an integer of 1 or 2; ℓ is an integer of 1 or 2; m is an integer of 1 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom. Preferable examples of the compound of the formula [I] are as follows: wherein m′ is an integer of 5 to 22; and n and C* are as defined above. wherein m, n and C * are as defined above. The liquid crystal compound of the formula [I] and intermediates for producing the same can be produced as follows. First, ethyl lactate is reduced by a reducing agent such as lithium aluminum hydride or lithium triethylborohydride/lithium borohydride in an organic solvent such as ethyl ether, isopropylether, tetrahydrofuran etc., with cooling to 25°C or lower to S(+)-1,2-propanediol. Then, S(+)-1,2-propanediol is converted to s(+)-2-hydroxypropyl p-toluenesulfonate using 0.5 to 1.5 equivalents of p-toluenesulfonyl chloride per equivalent of S(+)-1,2-propanediol in a solvent such as pyridine, or triethylamine, followed by a reaction with an alcohol in the presence of metallic sodium, metallic potassium, sodium hydride, sodium alcoholate, potassium alcoholate etc., for several hours at a temperature from room temperature to 150°C to give an intermediate of the formula: wherein C * and n are as defined above. The intermediate of the formula [X] can also be produced as follows: In order to protect the hydroxyl group of ethyl lactate, 3,4-dihydro-2H-pyran is used to form tetrahydropyranyl ether, which is reduced by lithium aluminum hydride or lithium triethylborohydride/lithium borohydride in a solvent such as ethyl ether, isopropyl ether, or tetrahydrofuran, with cooling to 25°C or lower to S(+)-2-(2-tetrahydropyranyloxy)propanol. Then, using p-toluenesulfonyl chloride, there is synthesized S(+)-2-(2-tetrahydropyranyloxy) propyl p-toluenesulfonate, which is reacted with an alcohol to produce the intermediate of the formula [X]. A compound of the formula: wherein n is an integer of 1 to 22; ℓ is an integer of 1 or 2; and C * is an asymmetric carbon, can be produced by reacting the compound of the formula: wherein n and C * are as defined above, with (i) 4-benzyloxybenzoic acid or a reactive derivative thereof, or (ii) 4-benzyloxybiphenylcarboxylic acid or a reactive derivative thereof preferably in an amount of 0.5 to 1.5 equivalents of the latter per equivalent of the compound of the formula [X] in the presence of a base preferably at a temperature from room temperature to a reflux temperature, more preferably 50°C or lower. The term "reactive derivative" means an acid chloride, acid anhydride, ester or the like conventionally used in this art. As the base, there can be used pyridine, a tertiary amine such as trimethylamine, N-methylmorpholine, or N-methyl pyrrolidine, an inorganic compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate, If necessary, there can be used a solvent such as an aromatic hydrocarbon, e.g. benzene, toluene, etc., a halogenated hydrocarbon, e.g. dichloromethane, dichloroethane, chloroform, carbon tetrachloride, etc. More concretely, the intermediate of the formula [X] is reacted with 0.5 - 1.5 equivalents of 4-benzyloxybenzoic acid or a reactive derivative thereof such as an acid chloride thereof to give an intermediate of the formula: wherein C* and n are as defined above. Alternatively the intermediate of the formula [X] can be reacted, for example, with 4-benzyloxybenzoyl chloride or 4-[4-(benzyloxyphenyl)benzoyl chloride to give an intermediate of the formula: wherein n and C* are as defined above. A compound of the formula: wherein ℓ is an integer of 1 or 2; n is an integer of 1 to 22; and C* is an asymmetric carbon atom, can be produced by reacting the compound of the formula: wherein ℓ, n and C * are as defined above with hydrogen in an organic solvent in the presence of a catalyst preferably at a temperature from room temperature to 50°C under an atmospheric pressure or under pressure, more preferably up to an initial hydrogen pressure of 10 kg/cm². As the catalyst, there can be used Raney nickel, 5-10% palladium on carbon, or a mixture thereof. More concretely, the intermediate of the formula [VIII] is then catalytically reduced by Raney nickel or 5-10% palladium on carbon in an organic solvent such as methanol, ethanol, ethyl acetate, tetrahydrofuran, or methylene dichloride, at room temperature to 50°C to give an intermediate of the formula: wherein C * and n are as defined above. Alternatively, the intermediate of the formula [IX] wherein ℓ is 2 is subjected to catalytic reduction with Raney nickel or 5-10% palladium or carbon at room temperature to 50°C to give an intermediate of the formula: wherein n and C* are as defined above. Finally, a liquid crystal compound of the formula: wherein k is an integer of 1 or 2; ℓ is an integer of 1 or 2; m is an integer of 1 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom, can be produced by reacting the compound of the formula: wherein ℓ, n and C* are as defined above, with (i) 4-alkyloxybenzoic acid or a reactive derivative thereof, or (ii) 4-alkyloxybiphenylcarboxylic acid or a reactive derivative thereof preferably in an amount of 0.5 to 1.5 equivalents of the latter per equivalent of the compound of the formula [VII] in the presence of a base preferably at a temperature from room temperature to a reflux temperature, more preferably 50°C or lower. The term "reactive derivative" means an acid chloride, acid anhydride, ester or the like conventionally used in this art. As the base, there can be used pyridine, a tertiary amine such as trimethylamine, N-methylmorpholine, or N-methylpyrrolidine, an inorganic compound such as sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate. If necessary, there can be used a solvent such as an aromatic hydrocarbon, e.g. benzene, toluene, etc., a halogenated hydrocarbon, e.g. dichloromethane, dichloroethane, chloroform, carbon tetrachloride, etc. More concretely, the intermediate of the formula [VI] or [VII] is then reacted, for example, with a 0.5 to 1.5 equivalents of 4-alkyloxybenzoyl chloride or 4-(4-alkyloxyphenyl) benzoyl chloride in the presence of a base such as pyridine, or triethylamine, at room temperature to a reflux temperature to give a liquid crystal compound of the formula [I]. In the case of the liquid crystal compound of the formula: wherein m', n and C * are as defined above, it can be obtained by reacting an intermediate of the formula [VI] for example, with a 0.5 to 1.5 equivalents of 4-alkyloxybenzoyl chloride in the presence of a base such as pyridine, or triethylamine at room temperature to a reflux temperature. As mentioned above, the intermediates of the formulae [X], [VIII], [VI], [IX] and [VII] are inevitable materials obtained by using ethyl lactate as a starting material for producing the liquid crystal compounds of the formula [I], including preferable examples of the formulae [II], [III], [IV] and [V]. Further, the liquid crystal compounds of the formula [I] can be produced easily and economically. The present invention is illustrated by way of the following Examples, in which all percents are by weight, unless otherwise specified. Example 1 Synthesis of S(+)-1-Pentyloxy-2-propanol (Compound [X], n=5) (1) Synthesis of S(-)-Ethyl 2-(2-tetrahydropyranyloxy)propionate S(-)-Ethyl lactate (88 g, 0.75 mol) was reacted with 3,4-dihydro-2H-pyran (191 g) in the presence of several drops of hydrochloric acid at 25±5°C for 12 h with stirring. The reaction mixture was neutralized with potassium carbonate, filtered to remove inorganic materials and then evaporated under reduced pressure. The residue was subjected to fractional distillation to give the title compound as a colorless oil having a 95.3% assay by G.C., area%; yield: 74 g (48.8%); bp 130-134°C/6.66 kPa (50 mmHg) [a] 25 / D : -20.8° ¹H NMR δppm (CDCl₃): 1.17 (3H, t, J=6Hz, -CH₂C H ₃), 1.43 (3H, d, J=6Hz, - HC H ₃), 1.53 - 1.93 (6H, m, THP 3,3-H 4,4-H 5,5-H), 3.37 - 4.90 (6H, m, - H -, -C H ₂CH₃ and THP 2-H 6,6-H). IR (Neat) νcm⁻¹ 2940, 2860, 1750. (2) Synthesis of S(-)-2-(2-Tetrahydropyranyloxy)propanol To a solution of lithium aluminum hydride (16.7 g) in dry tetrahydrofuran (600 ml), S(-)-ethyl 2-(2-tetrahydropyranyloxy)propionate (74 g, 0.366 mol) obtained in above (1) was added dropwise at 10°C or lower. The resultant mixture was stirred for 1 h at room temperature and then poured into H₂O. The mixture was extracted with ethyl ether (3 x 250 ml), the organic extract was evaporated, and the residue was distilled under reduced pressure to give the title compound as a colorless oil having a 96.7% assay by G.C., area%; yield : 37.6 g (75.2%); bp 110 - 130°C/1.99 kPa (15 mmHg). [a] 25 / D : -28.2° (Neat). ¹H NMR δppm (CDCl₃): 1.16 (3H, t, J=6Hz, -C H ₃), 1.40 - 2.00 (6H, m, THP 3,3-H 4,4-H 5,5-H), 3.36 - 4.10 (6H, m, -C H C H ₂O H and THP 6,6-H), 4,50 - 4.90 (1H, m, THP 2-H). IR (Neat) νcm⁻¹: 3450, 2940, 2860. (3) Synthesis of S(+)-2-(2-Tetrahydropyranyloxy)propyl p-toluenesulfonate To a S(-)-2-(2-tetrahydropyranyloxy)propanol (37.5 g, 0.237 mol) obtained in above (2) in pyridine (150 ml), p-toluenesulfonyl chloride (43.5 g) was added at 15°C or lower, and stirring was continued for 2 h at 10 - 15°C. The reaction mixture was evaporated under reduced pressure, the residue was diluted with H₂O and extracted with CH₂Cl₂. The organic layer was washed with H₂O, dried over MgSO₄ and then evaporated. The residue was chromatographed on silica gel (Wako Gel C-200, a trade name, manufactured by Wako Pure Chemical Industries, Ltd.) with n-hexane/CH₂Cl₂ (3:1) as eluent to give the title compound as a pale yellow viscous oil; yield : 70 g (94.6%). [α] 25 / D : +4.3° (Neat). ¹H NMR δppm (CDCl₃): 1.17 (3H, dd, J=6Hz, - HC H ₃), 1.42 - 1.88 (6H, m, THP 3,3-H 4,4-H 5,5-H), 2.43 (3H, s, Ar-C H ₃), 3.48 - 4.02 (5H, m, - H C H ₂- and THP 6,6-H), 4,50 - 4,60 (1H, m, THP 2-H), 7.27 (2H, d, J=8Hz, Ar3-H 5-H), 7.83 (2H, d, J=8Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 2960, 2880, 1610. (4) Synthesis of S(+)-1-Pentyloxy-2-propanol (Compound [X], n=5) S(+)-2-(2-Tetrahydropyranyloxy)propyl p-toluenesulfonate (40 g, 0.128 mol) obtained in above (3) was added dropwise to a solution of AmONa[prepared from Na (3.4 g) and amyl alcohol (228 g)] at 60°C and stirring was continued for 3 h at 60°C. The reaction mixture was taken up in H₂O, the organic layer was separated, washed with H₂O, dried over MgSO₄, and then evaporated under reduced pressure to give a yellow oily product (31 g) as a residue. After dissolving the residue in ethanol (370 ml), hydrochloric acid (7.4 g) was added to the resultant solution and refluxed for 30 min with stirring. The solvent was evaporated under reduced pressure and the residue was distilled under reduced pressure to give the title compound as a colorless oil having a 95.9% assay by G.C. area%; field : 9.2 g (49.2%); bp 120 - 122°C/11.99 kPa (90 mmHg). [a] 25 / D : +1.0° (Neat) ¹H NMR δppm (CDCl₃): 0.90 (3H, t, J=5Hz, -(CH₂)₄C H ₃), 1.13 (3H, d, J=6Hz, - H-C H ₃), 1.43 (6H, m, -CH₂-(C H ₂)₃-CH₃), 2.87 (1H, s, -O H ), 3,47 (4H, m, -C H ₂OC H ₂-), 3.87 (1H, m, H -CH₃). IR (Neat) νcm⁻¹: 3450, 2950, 2870 Example 2 Synthesis of S(+)-1-Propyloxy-2-propanol (Compound [X], n=3) S(+)-2-(2-Tetrahydropyranyloxy)propyl p-toluenesulfonate (47 g, 0.15 mol) obtained in Example 1, (3) was added dropwise to a solution of PrONa [prepared from Na (4.1 g) and n-propyl alcohol (160 ml)] at 60°C. Thereafter, the same procedure as described in Example 1, (4) was followed and distillation was carried out to give the title compound as a colorless oil having a 96.3% assay by G.C., area%; yield: 9.8 g (55.3%); bp 73 - 75°C/3.99 kPa (30 mmHg). [a] 25 / D :+0.23° (Neat). ¹H NMR δppm (CDCl₃): 0.93 (3H, t, J=7Hz, -CH₂C H ₃), 1.17 (3H, d, J=6Hz, -CH=C H ₃), 1.54 (2H, m, -C H ₂CH₃), 2.97 (1H, s, OH), 3.43 (4H, m, -C H ₂OC H ₂-), 3.97 (1H, m, C H ). IR (Neat ) νcm⁻¹: 3400, 2955, 2870. Example 3 Synthesis of S(+)-1-Ethyloxy-2-propanol (Compound [X], n=2) S(+)-2-(2-Tetrahydropyranyloxy)propyl p-toluenesulfonate (47 g, 0.15 mol) obtained in Example 1, (3) was added dropwise to a solution of EtONa [prepared from Na (4.1 g) and ethanol (150 ml)] at 60°C. Thereafter, the same procedure as described in Example 1, (4) was followed and distillation was carried out to give the title compound as a colorless oil having a 95.9% assay by G.C., area%; yield: 6.2 g (39.7%); bp 52 - 54°C/6.66 kPa (50 mmHg). [a] 25 / D: +4.6° (Neat). ¹H NMR δppm (CDC1₃): 1.13 (3H, d, J=7Hz, - H-C H ₃), 1.20 (3H, t, J=7Hz, -CH₂C H ₃), 2.70 (1H, s, O H ), 3,47 (4H, m, -C H ₂OC H ₂-) , 3.93 (1H, m, CH). IR (Neat) νcm⁻¹: 3400, 2950, 2850. Example 4 Synthesis of S(+)-1-Pentyloxy-2-propanol (Compound [X], n=5) (1) Synthesis of S(+)-1,2-propanediol To a solution of lithium aluminum hydride (78 g) in dry tetrahydrofuran (850 ml), S(-)-ethyl lactate (236.6 9, 2 mols) was added dropwise at 10°C or lower. The resultant mixture was stirred for 1 h at room temperature, then poured into H₂O and filtered to remove inorganic materials. The filtrate was washed with ethyl acetate, the aqueous layer was separated, concentrated under reduced pressure and the residue was distilled under reduced pressure to give the title compound as a colorless oil having a 96.9% assay by G.C., area%; yield: 78.2 a (51.4%); bp 80 - 80°C/0.799 kPa (6 mmHg.) [α] 25 / D: +16.0° (Neat). IR spectrum of this product was in good agreement with that of a commercially available material. (2) Synthesis of S(+)-2-Hydroxypropyl p-toluenesulfonate To a solution of S(+)-1,2-propanediol (78.2 g, 1.03 mol) obtained in above (1) in pyridine (530 ml), p-toluenesulfonyl chloride (167 g) was added at 15°C or lower and stirring was continued for 4 h at the same temperature. The reaction mixture was evaporated, the residue was diluted with H₂O and extracted with CH₂Cl₂. The organic layer was washed with H₂O, dried over MgSO₄ and then evaporated. The resultant residue was chromatographed on silica gel (Wako Gel C-200, manufactured by Wako Pure Chemical Industries, Ltd.) with CH₂Cl₂ as eluent to give the title compound as a pale yellow visous oil; yield: 117 g (58.0%. [α] 25 / D: +4.7° (Neat). ¹H NMR δppm (CDCl₃): 1.17 (3H, d, J=6Hz, - H-C H ₃), 2.47 (3H, s, Ar-C H ₃) , 2.77 (1H, bs, O H ), 3.97 (3H, m, - H -C H ₂-O-), 7.37 (2H, d, J=8Hz, Ar 3-H 5-H), 7.83 (2H, d, J=8Hz, Ar 2-H 6-H). (3) Synthesis of S(+)-1-Pentyloxy-2-propanol (Compound [X], n=5) S(+)-2-Hydroxypropyl p-toluenesulfonate (116 g, 0.50 mol) obtained in above (2) was added dropwise to a solution of AmONa [prepared from Na (13.8 g) and amyl alcohol (500 ml)] at 60°C and stirring was continued for 1 h at 60°C. The reaction mixture was taken up in H₂O, the organic layer was separated, washed with H₂O, dried over MgSO₄, and then evaporated. The residue was distilled under reduced pressure to give the title compound as a colourless oil having a 95.6% assay by G.C., area%, yield: 33.7 g (46.1%); bp 120 - 122°C/11.99 kPa (90 mmHg). [a] 25 / D: +1.0° (neat) IR, NMR and optical rotation data of this product were identical with those of the product as described for Example 1. Example 5 Synthesis of S(+)-1-Propyloxy-2-propanol (Compound [X], n=3) S(+)-2-Hydroxypropyl p-toluenesulfonate (45 g, 0.195 mol) obtained in Example 4, (2) was added dropwise to a solution of PrONa [prepared from Na (5.3 g) and n-propyl alcohol (150 ml)] at 60°C. Thereafter, the same procedure as described in Example 4, (3) was followed and distillation was carried out to give the title compound as a colorless oil having a 96.0% assay by G.C., area%; yield: 15.0 g (73.9%); bp 73 - 75°C/3.9 kPa (30 mmHg). [α] 25 / D: +0.23° (Neat) IR, NMR and optical rotation data of this product were identical with those of the product as described for Example 2. Example 6 Synthesis of S(+)-1-Ethyloxy-2-propanol (Compound [X], n=2) S(+)-2-Hydroxypropyl p-toluenesulfonate (66 g, 0.265 mol) obtained in Example 4, (2) was added dropwise to a solution of EtONa [prepared from Na (7.6 g) and ethanol (150 ml)] at 60°C. Thereafter, the same procedure as described in Example 4, (3) was followed and distillation was carried out to give the title compound as a colorless oil having a 96.6% assay by G.C., area%; yield: 18.4 g (62.0%); bp 52 - 54°C/6.66 kPa (50 mmHg). [a] 25 / D: +4.6° (Neat). IR, NMR and optical rotation data of this product were identical with those of the product as described for Example 3. Example 7 Synthesis of S(+)-1-Methyloxy-2-propanol (Compound [X], n=1) S(+)-2-Hydroxypropyl p-toluenesulfonate (23.1 g, 0.1 mol) obtained in Example 4, (2) was added dropwise to a solution of 28% sodium methoxide (21.3 g) in methanol (40 ml) at 50°C and stirring was continued for 1 h at 50°C. The reaction mixture was filtered to remove any insoluble material, evaporated and the residue gas subject to fractional distillation to give the title compound as a colorless oil having a 95.5% assay by G.C., area%; yield: 4.1 g (45.5%); bp 86 - 87°C. [α] 25 / D: +3.8° (c2, MeOH). ¹H NMR δppm (CDCl₃): 1.33 (3H, d, J=6Hz, - H-C H ₃), 3.06 (1H, bs, O H ), 3.30 (3H, s, OC H ₃), 3.57 (2H, d, J=6Hz, - HC H ₂O-), 3.83 - 3.94 (1H, m, C H ). IR (Neat) νcm⁻¹: 3350, 2950, 2850. Example 8 Synthesis of S(+)-1-Decyloxy-2-propanol (Compound [X], n=10) To a suspersion of metallic sodium (2.3 g) and decyl alcohol (31.6 g) in xylene (100 ml), S(+)-2-hydroxypropyl p-toluenesulfonate (21.0 g, 0.09 mol) obtained in Example 4, (2) was added dropwise at 90°C, and mixture was stirred for 3 h at 133 - 134°C. After cooling, the reaction mixture was taken up in H₂O, the organic layer was separated, washed with H₂O, dried over MgSO₄, and then evaporated. The residue was distilled to give the title compound as a colorless oil having a 97.4% assay by G.C., area%; yield: 6.4 g (32.7%); bp 150 - 152°C/2.39 kPa (18 mmHg). [a] 25 / D: +3.6°. (c2, MeOH) ¹H NMR δppm (CDCl₃): 0.90 (3H, t, J=6Hz, -(CH₂)₈-C H ₃), 1.03 - 1.90 (19H, m, - HC H ₃, -(C H ₂)₈-CH₃), 2.67 (1H, bs, O H ), 3.20 - 3.57 (4H, m, -C H ₂OC H ₂-), 3.73 - 4.17 (1H, m, - H CH₃). IR (Neat) νcm⁻¹: 3420, 2920, 2850. Example 9 Synthesis of S(+)-1-Pentyloxy-2-propyl 4-benzyloxybenzoate (Compound [VIII], n=5) (1) Synthesis of 4-Benzyloxybenzoic acid Ethyl p-hydroxybenzoate (200 g, 1.2 mol) was reacted with benzyl chloride (190 g, 1.5 mol) and potassium carbonate (165 g) for 12 h under reflux with stirring. After cooling, the mixture was filtered to remove inorganic materials, a half amount of acetone was evaporated, then was taken up in H₂O (1 ℓ) and extracted with CH₂Cl₂ (400 ml). The organic extract was washed with H₂O, dried over MgSO₄ and evaporated to give a yellow viscous oil (400 g) as a residue. Then the residue was stirred in H₂O (1 ℓ) and ethanol (500 ml) containing sodium hydroxide (60 g) for 4 h under reflux. After cooling, the reaction mixture was acidified with hydrochloric acid, the resultant precipitate was filtered, washed with H₂O, and recrystallized from ethanol to give the title compound as a white crystals; yield: 195 g (71.2%); mp 191.2 - 192.6°C. ¹H NMR δppm (CDCl₃-DMSO-d₆): 5.08 (2H, s, Ar-C H ₂O-), 6.93 (2H, d, J=8Hz, Ar 3-H 5-H), 7.37 (5H, s, ArH), 7.90 (2H, d, J=8Hz, Ar2-H 6-H), 8.53 (1H, bs, COOH). IR (KBr) νcm⁻¹: 2900, 2850, 2800, 2650, 2530, 1675, 1605. (2) Synthesis of S(+)-1-Pentyloxy-2-propyl 4-benzyloxybenzoate (Compound [VIII], n=5) To a solution of 4-benzyloxybenzoic acid (14.4 g, 63 mmol) obtained in above (1) in 1,2-dichloroethane, thionyl chloride (22.5 g) was added dropwise at 50 - 60°C, and stirring was continued for 2 h under reflux. The reaction mixture was evaporated to dryness and the resultant residue was suspended in pyridine (200 ml). To this solution, S(+)-1-pentyloxy-2-propanol (8.8 g, 60 mmol) obtained in Example 1, (4) was added dropwise at 20 - 25°C and stirred for 20 h at 20 - 25°C. The reaction mixture was filtered to remove any insoluble material, evaporated, diluted with H₂O and extracted with ethyl ether. The organic extract was evaporated and the resultant residue (15.5 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/EtOAc (10:1) as eluent to give the title compound as a pale yellow viscous oil; yield: 9.8 g (45.8%). [α] 25 / D: +21.8° (c2, MeOH). 1H NMR δppm (CDCl₃): 0.83 (3H, t, J=5Hz, -(CH₂)₄-C H ₃), 1.30 (3H, d, J=6Hz, - H-C H ₃), 1.30 (6H, m, -(C H ₂)₃-CH₃), 3.47 (4H, m, J=6Hz, - H ₂OC H ₂-), 5.70 (2H, s, Ar-C H ₂O-), 5.30 (1H, m, - H -CH₃), 7.00 (2H, d, J=8Hz, Ar3-H 5-H), 7.43 (5H, s, ArH), 8.06 (2H, d, J=8Hz, Ar2-H, 6-H). IR (Neat) νcm⁻¹: 2930, 2860, 1710, 1610. Example 10 Synthesis of S(+)-Propyloxy-2-propyl 4-benzyloxybenzoate (Compound [VIII], n=3) Using 4-benzyloxybenzoic acid (37.7 g, 0.165 mol) obtained in Example 9, (1), 4-benzoyloxy benzoylchloride was produced in the same manner as described in Example 9, (2), and then reacted with S(+)-1-propyloxy-2-propanol (15.0 g, 0.127 mol) obtained in Example 2 in the same manner as described in Example 9, (2) to give the title compound as a pale yellow viscous oil; yield: 21.0 g (50.3% [α] 25 / D: +26.2° (c2, MeOH). ¹H NMR δppm (CDCl₃): 0.80 (3H, t, J=6Hz, -CH₂C H ₃), 1.33 (3H, d, J=7Hz, - H-C H ₃), 1.33 (2H, m, -CH₂C H ₂CH₃), 3.43 (4H, m, J=6Hz, -C H ₂OC H ₂-), 5.03 (2H, s, Ar-C H ₂-), 5.30 (1H, m, - H-CH₃), 6.93 (2H, d, J=8Hz, Ar3-H 5-H), 7.33 (5H, s, ArH), 8.00 (2H, d, J=8Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹ : 2975, 2890, 1710, 1610. Example 11 Synthesis of S(+)-Ethyloxy-2-propyl 4-benzyloxybenzoate (Compound [VIII], n=2) Using 4-benzyloxybenzoic acid (52.5 g, 0.23 mol) obtained in Example 9, (1), 4-benzyloxybenzoylchloride was produced in the same manner as described in Example 9, (2), and then reacted with S(+)-1-ethyloxy-2-propanol (18.4 g, 0.177 mol) obtained in Example 3 in the same manner as described in Example 9, (2) to give the title compound as a pale yellow viscous oil; yield: 28.5 g (51.2%). [α] 25 / D: +22.1° (c2, MeOH). ¹H NMR δppm (CDCl₃): 1.16 (3H, t, J=7Hz, -CH₂C H ₃), 1.33 (3H, d, J=6Hz, - H-C H ₃), 3.50 (4H, m, J=6Hz, -C H ₂OC H ₂-), 5.03 (2H, s, Ar-C H ₂-), 5.30 (1H, m, - H-), 6.87 (2H, d, J=8Hz, Ar3-H 5-H), 7.30 (5H, s, ArH), 7.83 (2H, d, J=8Hz, Ar 2-H 6-H). IR (Neat) νcm⁻¹: 2980, 2880, 1710, 1610. Example 12 Synthesis of S(+)-1-Methyloxy-2-propyl 4-benzyloxy-benzoate (Compound [VIII, n=1) Using 4-benzyloxybenzoic acid (11.6 g, 0.051 mol) obtained in Example 9, (1), 4-benzyloxy-benzoyl chloride was produced in the same manner as described in Example 9, (2), and then reacted with S(+)-1-methyloxy-2-propanol (2.6 g, 0.029 mol) obtained in Exmple 7 in the same manner as described in Example 9, (2) to give the title compound as a pale yellow viscous oil; yield: 4.5 g (63.4%). [α] 25 / D: +16.4° (c1, MeOH). ¹H NMR δppm (CDCl₃): 1.36 (3H, d, J=6Hz, - H-C H ₃), 3.37 (3H, s, OC H ₃), 3.57 (2H, d, J=6Hz, - HC H ₂-), 5.07 (2H, s, Ar-C H ₂-), 5.05 - 5.53 (1H, m, J=6Hz, - H-CH₂-), 6.97 (2H, d, J=9Hz, Ar3-H 5-H), 7.37 (5H, s, ArH), 8.00 (2H, d, J=9Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 2980, 2930, 2880, 1780, 1700, 1605 Example 13 Synthesis of S(+)-1-Decyloxy-2-propyl 4-benzyloxybenzoate (Compound VIII], n=10) Using 4-benzyloxybenzoic acid (6.3 g, 0.028 mol) obtained in Example 9,(1), 4-benzyloxybenzoyl chloride was produced in the same manner as described in Example 9 (2), and then reacted with S(+)-1-decyloxy-2-propanol (6.0 g, 0.028 mol) obtained in Example 8 in the same manner as described in Example 9, (2) to give the title compound as a pale yellow viscous oil; yield: 8.5 g (71.4%). [α] 25 / D: +17.6° (c2, MeOH). ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₉-C H ₃), - .03 - 1.90 (19H, m, - H-C H ₃-, -CH₂(C H ₂)₈CH₃), 3.36 - 3.57 (4H, m, -C H ₂OC H ₂-), 5.06 (2H, s, Ar-C H ₂-), 5.03 -5.50 (1H, m, J=6Hz, - H -), 6.93 (2H, d, J=9Hz, Ar3-H 5-H), 7.33 (5H, s, ArH), 7.97 (2H, d, J=9Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 2950, 2870, 1715, 1610. Example 14 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-benzyloxyphenyl)benzoate (Compound [IX], n=2) (1) Synthesis of 4-(4-Benzyloxyphenyl)benzoic acid To a suspension of 60% sodium hydride (6 g) in dimethylformamide (DMF), ethyl 4-(4-hydroxyphenyl)benzoate (29.0 g, 0.12 mol) was added in small portions. The mixture was stirred for 15 min and then treated dropwise with benzyl chloride (19.0 g, 0.15 mol). The solution was stirred for 6 h under reflux. After cooling, the reaction mixture was taken up in H₂O, extracted with ethyl acetate, the organic extract was washed with H₂O and then dried over MgSO₄. The solvent was evaporated to give a pale yellow solid (30 g) as a residue. The residue was stirred in H₂O (150 ml) and ethanol (400 ml) containing sodium hydroxide (7.2 g) for 6 h under reflux. After cooling, the reaction mixture was acidified with hydrochloric acid, the resultant precipitate was filtered, washed with H₂O and warm ethanol to give the title compound as a white crystals; yield: 24 g (65.8%); mp 263.0 - 265.0°C. ¹H NMR δppm (CDCl₃-DMSO-d₆): 5.17 (2H, s, Ar-C H ₂-), 7.06 - 8.10 (14H, m, ArH and -COOH). IR (KBr) νcm⁻¹: 3100, 2950, 2750, 1700, 1625. (2) Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-benzyloxyphenyl)benzoate (Compound [IX], n=2) To a solution of 4-(4-benzyloxyphenyl)benzoic acid (18.0 g, 59 mmol) obtained in above (1) in toluene (50 ml), thoinyl chloride (21.1 g) was added dropwise at 50 - 60°C, and then stirring was continued for 6 h at 90 - 100°C. The mixture was evaporated to dryness and the resultant residue was suspended in pyridine (120 ml). To this solution, S(+)-1-ethyloxy-2-propanol (4.3 g, 57 mmol) obtained in Example 3 was added dropwise at 20 - 25°C and stirred for 8 h at 20 - 25°C. The reaction mixture was concentrated, diluted with H₂O and extracted with CH₂Cl₂. The organic extract was washed with H₂O, evaporated and the resultant residue (23 g) was chromatographed on silica gel (Wako Gel C-200, manufactured by Wako Pure Chemical Industries, Ltd.) with n-hexane/CH₂Cl₂ (3:1) as eluent to give the title compound as a pale yellow crystals; yield: 18.8 g (84.5%); mp 77.0 - 78.5°C. [α] 25 / D: +21.3° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 1.17 (3H, t, J-7Hz, -OCH₂C H ₃), 1.37 (3H, d, J=7Hz, - H-C H ₃), 3.27 - 3.73 (4H, m, -C H ₂OC H ₂-), 5.07 (2H, s, Ar-C H ₂-), 5.07 - 5.53 (1H, m, J=6Hz, - H -), 6.93 - 8.13 (13H, m, ArH). IR (KBr) νcm⁻¹: 2950, 2850, 1700, 1600. Example 15 Synthesis of S(+)-1-Pentyloxy-2-propyl 4-hydroxybenzoate (Compound [VI], n=5) S(+)-1-Pentyloxy-2-propyl 4-benzyloxybenzoate (4.6 g, 13 mmol) obtained in Example 9, (2) was reduced with hydrogen in the presence of 5% palladium on carbon (2 g) in ethyl acetate (150 ml) at 25°C and 101.325 kPa (1 atm). After absorbing a theoretical amount of hydrogen, the catalyst was filtered, the solvent was evaporated and the resultant residue (3.2 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (10:1) as eluent to give the title compound as a colorless viscous oil; yield: 3.0 g (86.6%) . [α] 25 / D: +32.2° (c2, MeOH). ¹H NMR δppm (CDCl₃) ; 0.86 (3H, t, J=5Hz, -(CH₂)₄C H ₃). 1.36 (3H, d, J=6Hz, - H-C H ₃), 1.36 (6H, m, -CH₂ (C H ₂)₃CH₃), 3.53 (4H, m, -C H ₂OC H ₂-), 5.30 (1H, m, - H -) , 6.80 (2H, d, J=8Hz, Ar3-H 5-H), 7.20 (1H, bs, Ar-O H ), 7.87 (2H, d, J=8Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 3300, 2940, 2870, 1690, 1610. Example 16 Synthesis of S(+)-1-Propyloxy-2-propyl 4-hydroxybenzoate (Compound [VI], n=3) S(+)-1-Propyloxy-2-propyl 4-benzyloxybenzoate (20 g, 0.06 mol) obtained in Example 10 was reduced with hydrogen in the presence of Raney nicked (1 g) in methanol (300 ml) at 25°C and 101.325 kPa (1 atm). Thereafter, the same procedure as described in Example 10 to give the title compound as a colorless viscous oil; yield: 14.0 g (97.8%). [α] 25 / D: +31.0° (c2, MeOH). ¹H NMR δppm (CDCl₃): 0.88 (3H, t, J=7Hz, -CH₂C H ₃), 1.33 (3H, d, J=6Hz, - H-C H ₃), 1.50 (2H, m, -C H ₂CH₃), 3.56 (4H, m, -C H ₂OC H ₂-), 5.33 (1H, m, - H -), 6.83 (2H, d, J=8Hz, Ar3-H 5-H), 7.93 (2H, d, J=8Hz, Ar2-H 6-H), 7.93 (1H, s, Ar-O H ) IR (Neat) νcm⁻¹: 3320, 2960, 2880, 1710, 1610. Example 17 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-hydroxybenzoate (Compound [VI], n=2) Using S(+)-1-ethyloxy-2-propyl 4-benzyloxybenzoate (28.0 g, 0.09 mol) obtained in Example 11, reduction was carried out in the same manner as described in Example 15 to afford the title compound as a colorless viscous oil; yield: 19.0 g (94.0%). [α] 25 / D: +26.2° (c2, MeOH). ¹H NMR δppm (CDCl₃): 1.23 (3H, t, J=7Hz, -CH₂C H ₃), 1.38 (3H, d, J=6Hz, - H-C H ₃), 3.56 (4H, m, -C H ₂OC H ₂-), 5.33 (1H, m, - H -), 6.93 (2H, d, J=8Hz, Ar3-H 5-H), 6.93 (1H, s, Ar-OH), 7.97 (2H, d, J=8Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 3300, 2980, 2880, 1710, 1610. Example 18 Synthesis of S(+)-1-Methyloxy-2-propyl 4-hydroxybenzoate (Compound [VI], n=1) Using S(+)-1-methyloxy-2-propyl 4-benzyloxybenzoate (4.5 g, 15 mmol) obtained in Example 12, reduction was carried out in the same manner as described in Example 15 to afford the title compound as a colorless visous oil; yield: 2.6 g (82.5%). [α] 25 / D: +19.2° (c1, MeOH). ¹H NMR δppm (CDCl₃): 1.36 (3H, d, J=6Hz, - H-C H ₃), 3.30 (3H, s, OC H ₃), 3.60 (2H, d, J=6Hz, -C H ₂O-), 4.63 (1H, s, Ar-O H ), 5.03 - 5.53 (1H, m, J=6Hz, - H -), 6.87 (2H, d, J=9Hz, Ar3-H 5-H), 7.93 (2H, d, J=9Hz, Ar2-H 6-H). IR (Neat) νcm⁻¹: 3250, 2980, 2930, 1685, 1605 Example 19 Synthesis of S(+)-1-Decyloxy-2-propyl 4-hydroxybenzoate (Compound [VI], n=10) Using S(+)-1-decyloxy-2-propyl 4-benzyloxybenzoate (8.5 g, 20 mmol) obtained in Example 13, reduction was carried out in the same manner as described in Example 15 to afford the title compound as a colorless viscous oil; yield: 6.2 g (92.1%). [α] 25 / D: +14.3° (c2, CHCl₃) ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₉C H ₃), 1.03 - 1.90 (19H, m, - H-C H ₃ , -CH₂(C H ₂)₈CH₃), 3.33 - 3.63 (4H, m, -C H ₂OC H ₂), 5.10 - 5.57 (1H, m, - H -), 6.83 (2H, d, J=9Hz, Ar3-H 5-H), 7.87 (3H, d, J=9Hz, Ar2-H 6-H and Ar-O H ). IR (Neat) νcm⁻¹: 3350, 2940, 2860, 1715, 1680, 1610. Example 20 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-hydroxyphenyl)benzoate (Compound [VII], n=2) Using S(+)-1-ethyloxy-2-propyl 4-(4-benzyloxyphenyl)benzoate (18.0 g, 46 mmol) obtained in Example 14, reduction was carried out in the same manner as described in Example 15 to give the title compound as white crystals; yield: 13.5 g (97.8%); mp 82.5 - 86.5°C. [α] 25 / D: +22.9° (c2, CHCl₃) ¹H NMR δppm (CDCl₃): 1.23 (3H, t, J=7Hz, -CH₂C H ₃), 1.30 (3H, d, J=6Hz, - H-C H ₃), 3.47-3.83 (4H, m, -C H ₂OC H ₂-), 5.10 - 5.57 (1H, m, J=6Hz, - H-), 6.83 - 8.13 (9H, m, ArH and Ar-O H ). IR (KBr) νcm⁻¹: 3250, 2950, 2860, 1700, 1600. Example 21 Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-decyloxybenzoyloxy)benzoate (Compound [II], m′=10, n=5) (1) Synthesis of 4-Decyloxybenzoic acid To a solution of decyl bromide (66.7 g, 0.3 mol), potassium carbonate (41.5 g) and sodium iodide (45.0 g) in acetone (500 ml), ethyl p-hydroxy benzoate (41.5 g, 0.25 mol) was added and stirring was continued for 24 h under reflux. After cooling, the reaction mixture was filtered to remove inorganic materials, taken up in H₂O (1 ℓ) and extracted with CH₂Cl₂ (2 x 100 ml). The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated to give a yellow visous oil (86 g) as a residue. The residue was stirred in H₂O (300 ml) and ethanol (200 ml) containing sodium hydroxide (18 g) for 6 h under reflux. After cooling, the reaction mixture was acidified with hydrochloric acid, the resultant precipitate was filtered, washed with H₂O and recrystallized from ethanol to give the title compound as white microneedles; yield: 28.5 g (40.8%); mp 95.2 - 97.4°C (the 1st mp), 122.8 - 124.4°C (the 2nd mp). ¹H NMR δppm (DMSO-d₆): 0.87 - 2.06 (19H, m, (C H ₂)₈-C H ₃), 3.97 (2H, t, J=6Hz, -C H ₂O-), 6.88 (2H, d, J=8Hz, Ar3-H 5-H), 7.90 (2H, d, J=8Hz, Ar2-H 6-H), 8.53 (1H, bs, -COO H ). IR (KBr) νcm⁻¹: 2925, 2850, 2650, 2550, 1680, 1605. (2) Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-decyloxybenzoyloxy)benzoate (Compound [II], m′=10, n=5) To a solution of 4-decyloxybenzoic acid (3.65 g, 13 mmol) obtained in above (1) in 1,2-dichloroethane, thionyl chloride (3.1 g) was added dropwise at 50 - 60°C, and then stirring was continued for 2 h under reflux. The mixture was evaporated to dryness and the resultant residue was suspended in pyridine (50 ml). To this solution, S(+)-1-pentyloxy-2-propyl 4-hydroxybenzoate (2.9 g, 11 mmol) obtained in Example 10 was added dropwise at 20 - 25°C and stirred for 20 h at 20 - 25°C. The reaction mixture was concentrated, diluted with H₂O and extracted with CH₂Cl₂. The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated. The resultant residue (6.1 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (10:1) as eluent to give a pale yellow solid (4.5 g). The solid was recrystallized thrice from ethanol to give the title compound as a white amorphous powder; yield: 3.6 g (62.1%); mp 41.5 - 41.9°C [α] 25 / D: +11.7° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.83 (6H, t, -(CH₂)₉C H ₃ and -(CH₂)₄C H ₃), 1.32 (25H, m, -CH₂(C H ₂)₈CH₃, - H-C H ₃ and -OCH₂(C H ₂)₃CH₃), 3.50 (4H, m, -C H ₂OC H ₂-), 4.13 (2H, t, -OC H ₂(CH₂)₈CH₃), 5.33 (1H, m, - H -), 6.87 (2H, d, J=8Hz, IR (KBr) νcm⁻¹: 2940, 2870, 1730, 1715, 1610. Anal. calcd. for C₃₂H₄₆O₆ : C%, 72.97; H%, 8.80 Found : C%, 73.05; H%, 8.76 Example 22 Synthesis of S(+)-1-Propyloxy-2-propyl 4-(4-decyloxybenzoyloxy)benzoate (Compound [II], m′=10, n=3) Using 4-decyloxybenzoic acid (3.65 g, 13 mmol) obtained in Example 21, (1), 4-decyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-propyloxy-2-propyl 4-hydroxybenzoate (2.6 g, 11 mmol) obtained in Example 16 in the same manner as described in Example 21, (2) to give the title compound as a white amorphous powder; yieid: 4.3 g (78.4%); mp 39.4 - 41.8°C. [α] 25 / D: +12.1° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.90 (6H, t, -(CH₂)₉C H ₃ and -OCH₂CH₂C H ₃), 1.13 (21H, m, -OCH₂(C H ₂)₈CH₃, - H-C H ₃ and -OCH₂C H ₂CH₃),3.53 (4H, m, -C H ₂OC H ₂-), 4.10 (2H, t, -OC H ₂(CH₂)₈CH₃), 5.33 (1H, m, - H -), IR (Neat) νcm⁻¹: 2930, 2870, 1740, 1605. Anal. calcd. for C₃₀H₄₂O₆: C%, 72.26; H%, 8.49 Found : C%, 72.27; H%, 8.44 Example 23 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-decyloxybenzoyloxy)benzoate (Compound [II], m′=10, n=2) Using 4-decyloxybenzoic acid (3.65 g, 13 mmol) obtained in Example 21, (1), 4-decyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-ethyloxy-2-propyl 4-hydroxybenzoate (2.5 g, 11 mmol) obtained in Example 17 in the same manner as described in Example 21, (2) to give the title compound as a white amorphous powder; yield: 3.7 g (69.4%); mp 34.2 - 37.8°C. [α] 25 / D: +11.6° (c2, CHCl₃) ¹H NMR δppm (CDCl₃): 0.87 (6H, t, -(CH₂)₉C H ₃ and -OCH₂C H ₃), 1.30 (19H, m, -OCH₂(C H ₂)₈CH₃ and - H -C H ₃), 3.56 (4H, n, -C H ₂OC H ₂-), 4.00 (2H, t, -OC H ₂(CH₂)₈CH₃), 5.27 (1H, m, - H -), IR (Neat) νcm⁻¹: 2930, 2855, 1735, 1720, 1605 Anal calcd. for C₂₉H₄₀O₆: C%, 71.87; H%, 8.32 Found : C%, 71.90; H%, 8.26 Example 24 Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-octyloxybenzoyloxy)benzoate (Compound [II], m′=8, n=5) (1) Synthesis of 4-Octyloxybenzoic acid Using ethyl p-hydroxybenzoate (36.7 g, 0.22 mol) and n-octyl bromide (50 g, 0.26 mol), the reaction was carried out in the same manner as described in Example 13, (1), and then recrystallized from ethanol to give the title compound as a white micro-needles; yield: 43.0 g (71.6%); mp 100.2 - 101.4°C (the 1st mp), 107.0 -107.6°C (the 2nd mp). ¹H NMR δppm (DMSO-d₆): 0.90 - 2.00 (15H, m, -(C H ₂)₆C H ₃), 4.00 (2H, t, J=6Hz, -C H ₂O-), 6.90 (2H, d, J=8Hz, Ar 3-H 5-H), 8.00 (2H, d, J=8Hz, Ar2-H 6-H), 8.00 (1H, bs, -COO H ). IR (KBr) νcm⁻¹: 2940, 2855, 2670, 2550, 1685, 1605. (2) Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-octyloxybenzoyloxy)benzoate (Compound [II], m′=8, n=5) Using 4-octyloxybenzoic acid (3.25 g, 13 mmol) obtained in above (1), 4-octyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-pentyloxy-2-propyl 4-hydroxybenzoate (2.9 g, 11 mmol) obtained in Example 15 in the same manner as described in Example 21 (2) to give the title compound as a white amorphous powder; yield: 3.8 g (69.3%); mp 29.0 - 30.5°C, [α] 25 / D: +12.1° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.90 (6H, t, -(CH₂)₇C H ₃ and -O(CH₂)₄CH₃), 1.30 (21H, m, -OCH₂(C H ₂)₆CH₃, - H -C H ₃ and -OCH₂(C H ₂)₃CH₃), 3.53 (4H, m, -C H ₂OC H ₂-), 4.06 (2H, t, -OC H ₂(CH₂)₆CH₃), 5.33 (1H, m, - H -), 6.97 (2H, d, J=8Hz, IR (Neat) νcm⁻¹: 2920, 2850, 1735, 1710, 1600 Anal. calcd. for C₃₀H₄₂O₆: C%, 72.26; H%, 8.49 Found: C%, 72.29; H%, 8.50 Example 25 Synthesis of S(+)-1-Propyloxy-2-propyl 4-(4-octyloxybenzoyloxy)benzoate (Compound [II], m′=8, n=3) Using 4-octyloxybenzoic acid (3.25 g, 13 mmol) obtained in Example 24, (1), 4-octyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-propyloxy-2-propyl 4-hydroxybenzoate (2.6 g, 11 mmol) obtained in Example 16 in the same manner as described in Example 21, (2) to give the title compound as a white amorphous powder; yield: 3.0 g (58.0%); mp 32.8 - 36.5°C. [α] 25 / D: +11.3° (c2, CHCl₃). ¹H NMR δ (CDCl₃): 0.90 (6H, t, -(CH₂)₇C H ₃ and -OCH₂CH₂C H ₃), 1.33 (17H, m, -OCH₂(C H ₂)₆CH₃, - H-C H ₃ and -OCH₂C H ₂CH₃), 3.56 (4H, m, -C H ₂OC H ₂-), 4.05 (2H, t, -OC H ₂) (CH₂)₆CH₃), 5.33 (1H, m, - H -), 6.97 (2H, d, J=8Hz, IR (Neat) νcm⁻¹: 2925, 2855, 1735, 1720, 1605. Anal. calcd. for C₂₈H₃₆O₆: C%, 71.46; H%, 8.14 Found : C%, 71.50, H%, 8.10. Example 26 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-octyloxybenzoyloxy)benzoate (Compound [II], m′=8, n=2) Using 4-octyloxybenzoic acid (3.25 g, 13 mmol) obtained in Example 24, (1), 4-octyloxybenzoyl chloride was produced in the same manner as described in Example 21 (2), and then reacted with S(+)-1-ethyloxy-2-propyl 4-hydroxybenzoate (2.5 g, 11 mmol) obtained in Example 17 in the same manner as described in Example 21 (2) to give the title compound as a white leaflets; yield: 4.0 g (79.6%); mp 40.2 - 43.3°C. [α] 25 / D: +12.0° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.87 (6H, t, -(CH₂)₇C H ₃ and OCH₂C H ₃), 1.30 (15H, m, -OCH₂(C H ₂)₆CH₃ and - H-C H ₃), 3.56 (4H, m, -C H ₂OC H ₂), 4.00 (2H, t, -OC H ₂(CH₂)₆CH₃), 5.30 (1H, m, - H -), IR (Neat) νcm⁻¹: 2930, 2855, 1735, 1720, 1605. Anal. calcd. for C₂₇H₃₆O₆: C%, 71.03; H%, 7.95 Found : C%, 71.11; H%, 7.93 Example 27 Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-heptyloxybenzoyloxy)benzoate (Compound [II], m′=7, n=5) (1) Synthesis of 4-Heptyloxybenzoic acid Using ethyl p-hydroxybenzoate (33.3 g, 0.20 mol) and n-heptyl bromide (39.4 g, 0.22 mol), the reaction was carried out in the same manner as described in Example 21, (1), and then recrystallized from ethanol to give the title compound as a white microneedles; yield: 19.0 g (40.2%); mp 86.2 - 90.3°C. ¹H NMR δppm (DMSO-d₆): 0.80 - 2.10 (13H, m, -(C H ₂)₅-C H ₃), 4.03 (2H, t, J=6Hz, -C H ₂O-), 6.93 (2H, d, J=8Hz, Ar3-H 5-H), 8.00 (2H, d, J=8Hz, Ar2-H 6-H), 8.00 (1H, bs, -COO H ) IR (KBr) νcm⁻¹: 2900, 2830, 2640, 2520, 1670, 1600. (2) Synthesis of S(+)-1-Pentyloxy-2-propyl 4-(4-heptyloxybenzoyloxy)benzoate (Compound [II], m′=7, n=5) Using 4-heptyloxybenzoic acid (3.07 g, 13 mmol) obtained in above (1), 4-heptyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-pentyloxy-2-propyl 4-hydroxybenzoate (2.9 g, 11 mmol) obtained in Example 15 in the same manner as described in Example 21, (2) to give the title compound as a white needles; yield: 3.7 g (69.4%); mp 32.0 - 36.5°C. [α] 25 / D: +12.8° (c2, CHCl₃). ¹H (NMR δppm (CDCl₃): 0.90 (6H, t, -(CH₂)₆C H ₃ and -O(CH₂)₄C H ₃), 1.30 (19H, m, -OCH₂ (C H ₂)₅CH₃, - H-C H ₃ and -OCH₂(C H ₂)₃CH₃), 3.53 (4H, m, -C H ₂OC H ₂-), 4.03 (2H, t, -OC H ₂(CH₂)₅CH₃), 5.33 (1H, m, - H -), 6.97 (2H, d, J=8Hz, IR (Neat) νcm⁻¹: 2930, 2855, 1735, 1720, 1600 Anal. calcd. for C₂₉H₄₀O₆: C%, 71.87; H%, 8.32 Found : C%, 71.89, H%, 8.30 Example 28 Synthesis of S(+)-1-Propyloxy-2-proply 4-(4-heptyloxybenzoyloxy)benzoate (Compound [II], m′=7, n=3) Using 4-heptyloxybenzoic acid (3.07 g, 13 mmol) obtained in Example 27, (1), 4-heptyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-propyloxy-2-propyl 4-hydroxybenzoate (2.6 g, 11 mmol) obtained in Example 16 in the same manner as described in Example 21, (2) to give the title compound as a white needles; yield: 3.3 g (65.7%); mp 46.2 - 49.2°C. [α] 25 / D: +11.9° (c2, CHCl₃) ¹H NMR δppm (CDCl₃): 0.87 (6H, t, -(CH₂)₆C H ₃ and -OCH₂CH₂C H ₃), 1.30 (15H, m, -OCH₂(C H ₃)₅CH₃, - H-C H ₃ and -OCH₂C H ₂CH₃), 3.47 (4H, m, -C H ₂OC H ₂-), 4.00 (2H, t, -OC H ₂(CH₂)₅CH₃), 5.27 (1H, m, -C H -), 6.87 (2H, d, J=8Hz, IR (Neat) νcm⁻¹: 2945, 2860, 1735, 1720, 1605. Anal. calcd. for C₂₇H₃₆O₆: C%, 71.03; H%, 7.95 Found : C%, 71.07, H%, 7.86 Example 29 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-heptyloxybenzoyloxy)benzoate (Compound [II], m′=7, n=2) Using 4-heptyloxybenzoic acid (3.07 g, 13 mmol) obtained in Example 27, (1), 4-heptyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2) and then reacted with S(+)-1-ethyloxy-2-propyl 4-hydroxybenzoate (2.5 g, 11 mmol) obtained in Example 17 in the same manner as described in Example 21, (2) to give the title compound as a white leaflets; yield: 3.3 g (67.8%); mp 41.2 - 44.3°C. [α] 25 / D: +13.6° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.90 (6H, t, -(CH₂)₆C H ₃ and -OCH₂C H ₃), 1.33 (13H, m, -OCH₂(C H ₂)₅CH₃ and - H-C H ₃), 3.57 (4H, m, -C H ₂OC H ₂), 4.03 (2H, t, -OC H ₂(CH₂)₅CH₃), 6.97 (2H, d, J=8Hz, IR (Neat) νcm⁻¹: 2925, 2855, 1735, 1715, 1605. Anal. calcd. for C₂₆H₃₄O₆: C%, 70.56; H%, 7.74 Found : C%, 70.67, H%, 7.63 Example 30 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-pentyloxybenzoyloxy)benzoate (Compound [II], m′=5, n=2) (1) Synthesis of 4-Pentyloxybenzoic acid To a solution of pentyl brimde (25 g, 0.17 mol), potassium carbonate (20.8 g) and potassium iodide (25 g) in acetone (200 ml), ethyl p-hydroxybenzoate (25 g, 0.15 mol) was added and stirring was continued for 12 h under reflux. After cooling, the reaction mixture was filtered to remove inorganic materials, and evaporated. The residue was taken up in CH₂Cl₂ (300 ml), washed with H₂O, dried over MgSO₄ and evaporated to give a colorless viscous oil (30 g) as a residue. The residue was solidified when cooled; mp 30.5 - 34.0°C. Then the residue was stirred in H₂O (120 ml) and ethanol (50 ml) containing sodium hydroxide (7.4 g) for 4 h under reflux. After cooling, the reaction mixture was acidified with hydrochloric acid, the resultant precipitate was filtered, washed with H₂O and recrystallized from ethanol to give the title compound as a white needles; yield: 18.0 g (70.3%); mp 123.0 - 124.5°C. ¹H NMR δppm (CDCl₃-CMSO-d₆): 0.90 (3H, t, J=6Hz, -CH₂C H ₃), 1.23 - 1.96 (6H, m, -CH₂(C H ₂)₃CH₃), 4.03 (2H, t, J=7Hz, Ar-OC H ₂-), 6.97 (2H, d, J=9Hx, Ar3-H 5-H), 7.95 (2H, d, J=9Hz, Ar2-H 6-H), 12.50 (1H, bs, -COO H ) IR (KBr) νcm⁻¹: 2940, 2860, 2650, 2530, 1670, 1605. (2) Synthesis of S(+)-1-Ethyloxy-2-propyl 4-(4-pentyloxybenzoyloxy)benzoate (Compound [II], m′=5, n=2) To a solution of 4-pentyloxybenzoic acid (4.0 g, 19 mmol) obtained in above (1) in 1,2-dichloroethane, thionyl chloride (4.0 g) was added dropwise at 50 - 60°C, and then stirring was continued for 2 h under reflux. The mixture was evaporated to dryness and the resultant residue was suspended in pyridine (50 ml). To this solution, S(+)-1-ethyloxy-2-propyl 4-hydroxybenzoate (4.0 g, 17 mmol) obtained in Example 17 was added dropwise at 20 - 25°C and stirred for 12 h at 20 - 25°C. The reaction mixture was concentrated, diluted with H₂O and extracted with CH₂Cl₂. The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated. The resultant residue (13 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (20:1) as eluent to give a pale yellow solid (6.1 g). The solid was recrystallized twice from ethanol to give the title compound as a white leaflets; yield: 3.1 g (57.0%); mp 64.0 - 68.0°C. [α] 25 / D: +12.3° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.90 - 2.00 (15H, m, -CH₂(C H ₂)₃C H ₃, -CH-C H ₃ and -OCH₂C H ₃), 3.33 - 3.73 (4H, m, -C H ₂OC H ₂-), 4.00 (2H, t, J=6Hz, Ar-OC H ₂-), 5.06 - 5.53 (1H, m, - H -), 6.83 - 7.33 (4H, m, IR (Kbr) νcm⁻¹: 2900, 2850, 1720, 1610. Anal. calcd. for C₂₄H₃₀O₆: C%, 69.54; H%, 7.29 Found : C%, 69.59; H%, 7.33. Example 31 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-{4-(4-decyloxyphenyl)benzoyloxy}benzoate (Compound [IV], m=10, n=2) (1) Synthesis of 4-Decyloxy-1,1′-biphenyl 4-Hydroxy-1,1′-biphenyl (61.3 g, 0.36 mol) and decyl bromide (218 g, 0.72 mol) were heated at 80°C. To this solution, a 50% potassium hydroxide aqueous solution (57 g) was added dropwise at 80°C and then stirring was continued for 6 h at the same temperature. After cooling, the mixture was diluted with ethyl acetate, the organic layer was separated, washed with H₂O and dried over MgSO₄. The solvent was removed under reduced pressure and the resultant residue was recrystallized from a mixed solvent of n-hexane and ethyl acetate to give the title compound as a white crystals; yield: 70 g (62.6%); mp 70.0 - 73.0°C. (2) Synthesis of 4-Acetyl-4′-decyloxy-1,1′-biphenyl To a solution of 4-decyloxy-1,1′-biphenyl (15.5 g, 0.05 mol) obtained in above (1) and aluminum chloride (7.6 g) in carbon disulfide, acetyl chloride (4 g, 0.054 mol) was added dropwise at 20 - 25°C, and stirring was continued for 2 h under reflux. After cooling, the reaction mixture was poured into 6N hydrochloric acid (100 ml), concentrated to remove carbon disulfide, and extracted with ethyl acetate. The organic extract was washed with H₂O, dried over MgSO₄, evaporated under reduced pressure and the resultant residue (18.5 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (4:1) as eluent to give the title compound as a white crystals; yield: 4.5 g (25.5%); mp 101.8 - 103.5°C (the 1st mp), 121.0 - 124.0°C (the 2nd mp). ¹H NMR δppm (CDCl₃): 0.90 (3H, t, J=6Hz, -(CH₂)₉C H ₃), 1.10 - 2.10 (16H, m, -CH₂(C H ₂)₈CH₃), 2.60 (3H, s, -COC H ₃), 4.00 (2H, t, J=6Hz, -C H ₂O-), 6.97 (2H, d, J=9Hz, Ar3′-H 5′-H), 7.47 -7.67 (4H, m, Ar2-H 6-H 2′-H 6′-H), 7.97 (2H, d, J=9Hz, Ar3-H 5-H). IR (KBr) νcm⁻¹: 2980, 2910, 1690, 1610. (3) Synthesis of 4-(4-Decyloxyphenyl)benzoic acid To a solution of 4-acetyl-4′-decyloxy-1,1′-biphenyl (4.2 g, 0.012 mol) in 1,4-dioxane (20 ml), an aqueous solution of sodium hypobromite (40 ml) [freshly prepared from sodium hydroxide (7.9 g) and bromine (7.1 g)] was added dropwise at 20 - 25°C, and stirring was continued for 2 h at 40°C. After cooling, sodium bisulfite was added to destroy excess sodium hypobromite and the mixture was acidified with hydrochloric acid. The resultant precipitate was filtered, washed with H₂O and dried to give the title compound as a white amorphous powder; yield: 3.5 g (90.1%); mp 245.5 - 250.0°C. ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₈C H ₃), 1.10 - 2.07 (16H, m, -CH₂(C H ₂)₈CH₃), 4.17 (2H, 5, J=6Hz, -C H ₂O-) 7.10 (2H, d, J=9Hz, IR (KBr) νcm⁻¹: 2940, 2860, 2680, 2560, 1685, 1605. (4) Synthesis of S(+)-1-Ethyloxy-2-propyl 4-{4-(4-decyloxyphenyl)benzoyloxy}benzoate. (Compound [IV], m=10, n=2) To a solution of 4-(4-decyloxyphenyl)benzoic acid (5.2 g, 14.7 mmol) obtained in above (3) in 1,2-dichloroethane, thionyl chloride (5.2 g) was added dropwise at 50 - 60°C, and then stirring was continued for 2 h under reflux. The mixture was evaporated to dryness and the resultant residue was suspended in pyridine (120 ml). To this solution, S(+)-1-ethyloxy-2-propyl 4-hydroxybenzoate (3 g, 13.4 mmol) obtained in Example 17 was added dropwise at 20 - 25°C and stirred for 4 h at 40°C. The reaction mixture was concentrated, diluted with H₂O and extracted with CH₂Cl₂. The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated. The resultant residue was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (3:1) as eluent to give a pale yellow solid (6.0 g). The solid was recrystallized twice from ethanol to give the title compound as a white microneedles; yield: 4.3 g (58.9%); mp 70.5 - 74.0°C (the 1st mp), 157.5 -158.5°C (the 2nd mp. [α] 25 / D: +10.0° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₉C H ₃), 1.07 - 1.87 (22H, m, -CH₂(C H ₂)₈CH₃, - H-C H ₃ and -OCH₂C H ₃), 3.40 - 3.73 (4H, m, -C H ₂OC H ₂-), 4.00 (2H, t, J=6Hz, Ar-OC H ₂-), 5.10 - 5.47 (1H, m, J=6Hz, - H -), 6.90 - 8.23 (12H, m, ArH). IR (KBr) νcm⁻¹: 2930, 2850, 1740, 1720, 1605 Anal. calcd. for C₃₅H₄₄O₆: C%, 74.97; H%, 7.91 Found : C%, 75.11: H%, 7.78 Example 32 Synthesis of S(+)-1-Hethyloxy-2-propyl 4-(4-decyloxybenzoyloxy)benzoate (Compound [II], m′=10, n=1) Using 4-decyloxybenzoic acid (3.5 g, 12.5 mmol) obtained in Example 21, (1), 4-decyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), and then reacted with S(+)-1-methyloxy-2-propyl 4-hydroxybenzoate (2.3 g, 11 mmol) obtained in Example 18 in the same manner as described in Example 21, (2) to give the title compound as a colorless viscous oil; yield: 4.0 g (77.2%). [α] 25 / D: +9.2° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₈C H ₃), 1.07 - 2.03 (19H, m, -CH₂(C H ₂)₈CH₃ and - H-C H ₃), 3.17 (3H, s, OC H ₃), 3.57 (2H, d, J=6Hz, -C H ₂OCH₃), 4.00 (2H, t, J=6Hz, Ar-OC H ₂-), 5.07-5.57 (1H, m, J=6Hz, - H-), 6.93 (2H, d, J=9Hz, IR (Neat) νcm⁻¹: 2920, 2850, 1740, 1720, 1605. Anal. calcd. for C₂₈H₃₈O₆: C%, 71.46; H%, 8.14 Found : C%, 71.58, H%, 8.01 Example 33 Synthesis of S(+)-1-Decyloxy-2-propyl 4-(4-docosyloxybenzoyloxy)benzoate (Compound [II], m′=22, n=10) (1) Synthesis of 4-Docosyloxybenzoic acid To a solution of docosyl bromide (25 g, 0.064 mol), potassium carbonate (9.0 g) and sodium iodide (9.6 g) in acetone (150 ml), ethyl p-hydroxybenzoate (10.2 g, 0.061 mol) was added, and then reacted for 12 h under reflux with stirring. After cooling, the reaction mixture was filtered to remove inorganic materials, taken up in H₂O (500 ml), and extracted with CH₂Cl₂(3 x 100 ml). The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated to dryness. The resultant residue was recrystallized from ethyl acetate to give ethyl 4-docosyloxybenzoate (27 g) as a white crystals; mp 56.5 - 59.5°C. Then ethyl 4-docosyloxybenzoate (27 g) was stirred in H₂O (120 ml) and ethanol (150 ml) containing sodium hydroxide (4.6 g) for 6 h under reflux. After cooling, the reaction mixture was acidified with hydrochloric acid, the resultant precipitate was filteted, washed with H₂O and recrystallized from acetic acid to give the title compound as a white needles; yield: 18.5 g (72.7%); mp 99.0 - 101.5°C. ¹H NMR δppm (CDCl₃-DMSO-d₆): 0.87 (3H, t, J=6Hz, -(CH₂)₂₀C H ₃), 1.00 - 2.06 (40 H, m, -OCH₂(C H ₂)₂₀CH₃), 4.07 (2H, t, J=6Hz, -OC H ₂(CH₂)₂₀-), 6.83 (2H, d, J=9Hz, Ar3-H 5-H), 8.00 (2H, d, J=9Hz, Ar2-H 6-H), 12.37 (1H, bs, -COO H ). IR (KBr) νcm⁻¹: 2910, 2850, 1670, 1605. (2) Synthesis of S(+)-1-Decyloxy-2-propyl 4-(4-docosyloxybenzoyloxy)benzoate (Compound [II], m′=22, n=10) To a solution of 4-docosyloxybenzoic acid (4.4 g, 10 mmol) obtained in above (1) in toluene (30 ml), thionyl chloride (2.4 g) was added dropwise at 50 - 60°C, and then stirring was continued for 1 h at 90 - 100°C. The mixture was concentrated to dryness and the resultant residue was suspended in pyridine (35 ml). To this solution, S(+)-1-decyloxy-2-propyl 4-hydroxybenzoate (3.0 g, 9 mmol) obtained in Example 19 was added dropwise at 20 - 25°C and stirred for 3 h at the same temperature. The reaction mixture was concnetrated, diluted with H₂O and extracted with CH₂Cl₂. The organic layer was separated, washed with H₂O, dried over MgSO₄, and evaporated. The resultant residue (7.5 g) was chromatographed on silica gel (Wako Gel C-200) with n-hexane/ethyl acetate (4:1) as eluent and further recrystallized twice from a mixed solvent of ethyl acetate and ethanol to give the title compound as a white microneedles; yield: 2.5 g (36.2%); mp 51.0 -59.5°C [α] 25 / D: +6.8° (c2, CHCl₃) ¹H NMR δppm (CDCl₃): 0.87 (6H, t, J=6Hz, -O(CH₂)₂₁C H ₃ and -O(CH₂)₉C H ₃), 1.03 - 1.97 (59H, m, -OCH₂(C H ₂)₂₀CH₃, - H-C H ₃ and -OCH₂(C H ₂)₈CH₃), 3.37 - 3.60 (4H, m, -C H ₂OC H ₂-), 4.02 (2H, t, J=6Hz, Ar-OC H ₂-), 5.07 - 5.43 (1H, m, J=6Hz, - H -), 6.93 (2H, d, J=9Hz, IR (KBr) νcm⁻¹: 2940, 2870, 1740, 1720, 1610. Anal. calcd. for C₄₉H₈₀O₆: C%, 76.92; H%, 10.54 Found : C%, 77.09; H%, 10.38 Example 34 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-{4-(4-decyloxybenzoyloxy)phenyl}benzoate (Compound [III], m=10, n=2) Using 4-decyloxybenzoic acid (4.2 g, 15 mmol) obtained in Example 21, (1), 4-decyloxybenzoyl chloride was produced in the same manner as described in Example 21, (2), then reacted with S(+)-1-ethyloxy-2-propyl 4-(4-hydroxyphenyl)benzoate (4.1 g, 13.5 mmol) obtained in Example 20 in the same manner as described in Example 21, (2) and further recrystallized twice from a mixed solvent of ethyl acetate and ethanol to give the title compound as a white amorphous powder; yield: 5.2 g (68.7%); mp 56.0 - 58.5°C (the 1st mp), 139.5 - 140.5°C (the 2nd mp); [α] 25 / D: +10.8° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₈C H ₃), 1.07 - 1.90 (22H, m, -(C H ₂)₈CH₃, - H-C H ₃ and -OCH₂C H ₃), 3.37 - 3.73 (4H, m, -C H ₂OC H ₂-), 4.00 (2H, t, J=6Hz, Ar-OC H ₂-), 5.07 - 5.47 (1H, m, J=6Hz, - H -), 6.87 - 8.20 (12H, m, ArH). IR (KBr) νcm⁻¹: 2900, 2820, 1720, 1605. Anal. calcd. for C₃₅H₄₄O₆: c%, 74.94; H%, 7.91 Found : C%, 75.12; H%, 7.76 Example 35 Synthesis of S(+)-1-Ethyloxy-2-propyl 4-{4-[4-(4-decyloxyphenyl)benzoyloxy]phenyl}benzoate (Compound [I], k=2, l=2, m=10, n=2) Using 4-(4-decyloxyphenyl)benzoic acid (2.0 g, 5.6 mmol) obtained in Example 31, (3), 4-(4-decyloxyphenyl)benzoyl chloride was produced in the same manner as described in Example 31, (4), then reacted with S(+)-1-ethyloxy-2-propyl 4-(4-hydroxyphenyl)benzoate (1.7 g, 5.6 mmol) obtained in Example 20 in the same manner as described in Example 31, (4) and further recrystallized twice from a mixed solvent of n-hexane and ethyl acetate to give the title compound as a white amorphous powder; yield: 1.5 g (42.1%); mp 102.0 -104.0°C (the 1st mp), 258.0 - 259.0°C (the 2nd mp); [α] 25 / D: +10.3° (c2, CHCl₃). ¹H NMR δppm (CDCl₃): 0.87 (3H, t, J=6Hz, -(CH₂)₈C H ₃), 1.07 - 1.90 (22H, m, -(C H ₂)₈CH₃ - H-C H ₃ and -OCH₂C H ₃), 3.47 - 3.73 (4H, m, -C H ₂OC H ₂-), 4.07 (2H, t, J=6Hz, Ar-OC H ₂-), 6.98 - 8.27 (16H, m, ArH). IR (KBr) νcm⁻¹: 2920, 2850, 1735, 1720, 1605. Anal. calcd. for C₄₁H₄₈O₆: C%, 77.33; H%, 7.60 Found: C%, 77.39; H%, 7.51. Application Example 1 Phase transition temperatures of the liquid crystal compounds obtained in Examples 21 to 35 according to the present invention were measured by using a differential scanning calorimeter and a polarization microscope and shown in Table 1. In Table 1, a black point means the presence of a phase. Figures show transition temperatures and those in parentheses show the values at a time of temperature decrease. Further, abbreviations in Table 1 have the following meaning: As explained above, the liquid crystal compounds of the present invention show a liquid crystal phase at near room temperature and temperatures higher than room temperature, and thus can be applied as ferroelectric liquid crystal materials operable at room temperature and as components constituting such ferroelectric liquid crystal materials. Further, the liquid crystal compounds of the present invention have a chemically stable molecular structure, can provide larger spontaneous polarization due to having an asymmetric carbon atom near an aromatic ring and are excellent in practical use. In addition, processes used in the present invention are effective for producing the liquid crystal compounds and intermediates thereof, said liquid crystal compounds showing a liquid crystal phase at near room temperature and higher.

Claims: A liquid crystal compound of the formula: wherein m is an integer of 1 to 22; n is an integer of 1 to 22; k and ℓ are independently an integer of 1 or 2; and C* is an asymmetric carbon atom. A liquid crystal compound according to Claim 1, which is represented by the formula: wherein m′ is an integer of 5 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom. A liquid crystal compound according to Claim 1, which is represented by the formula: wherein m is an integer of 1 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom. A liquid crystal compound according to Claim 1, which is represented by the formula: wherein m is an integer of 1 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom. A liquid crystal compound according to Claim 1, which is represented by the formula: wherein m is an integer of 1 to 22; n is an integer of 1 to 22; and C* is an asymmetric carbon atom. An intermediate for synthesizing a liquid crystal compound and represented by the formula: wherein n is an integer of 1 to 22; and C* is an asymmetric carbon atom. An intermediate for synthesizing a liquid crystal compound and represented by the formula: wherein n is an integer of 1 to 22; and C* is an asymmetric carbon atom. An intermediate for synthesizing a liquid crystal compound and represented by the formula: wherein n is an integer of 1 to 22; and C * is an asymmetric carbon atom. An intermediate for synthesizing a liquid crystal compound and represented by the formula: wherein n is an integer of 1 to 22; and C * is an asymmetric 10 carbon atom. A process for producing a liquid crystal compound of the formula: wherein k is an integer of 1 or 2; ℓ is an integer of 1 or 2; m is an integer of 1 to 22; n is an integer of 1 to 22; and C * is an asymmetric carbon atom, which comprises reacting a compound of the formula: wherein ℓ, n and C * are as defined above, with (i) 4-alkyloxybenzoic acid or a reactive derivative thereof, or (ii) 4-alkyloxybiphenylcarboxylic acid or a reactive derivative thereof, in the presence of a base. A process for producing a compound of the formula: wherein ℓ is an integer of 1 or 2; n is an integer of 1 to 22; and C * is an asymmetric carbon atom, which comprises reacting a compound of the formula; wherein ℓ, n and C* are as defined above with hydrogen in an organic solvent in the presence of a catalyst. A process for producing a compound of the formula: wherein n is an integer of 1 to 22; ℓ is an integer of 1 or 2; and C * is an asymmetric carbon, which comprises reacting a compound of the formula: wherein n and C * are as defined above, with (i) 4-benzyloxybenzoic acid or a reactive derivative thereof, or (ii) 4-benzyloxybiphenylcarboxylic acid or a reactive derivative thereof, in the presence of a base.

Inventors: ISHIBASHI, SHIGEKI C/O DENSHI OYO KENKYUSHO OF NTT, MARUNO, TOHRU C/O DENSHI OYO KENKYUSHO OF NTT, NAKAHATA, MASAAKI C/O TOKYO KENKYU HONBU, NAKAMURA, KOUZABUROU  DENSHI OYO KENKYUSHO OF NTT, NEGISHI, TAKAAKI C/O TOKYO KENKYU HONBU, URANO, FUMIYOSHI C/O TOKYO KENKYU HONBU, Nakamura, Kouzaburou Denshi Oyo Kenkyusho of NTT
Applicants: NIPPON TELEGRAPH AND TELEPHONE CORPORATION, WAKO PURE CHEMICAL INDUSTRIES, LTD.
Application year: 1988
Main classification: C09K19
IPC codes: C07C43, C07C69, C09K19