Trans-decacyclene indole liquid crystal compounds and methods for their preparation

Abstract

The application belongs to the technical field of liquid crystal materials, and relates to a trans-decahydronaphthalene indole liquid crystal compound and a preparation method thereof. The application provides a trans-decahydronaphthalene indole liquid crystal compound, which has a chemical structural formula as shown in formula (I). The preparation of the compound of formula (I) comprises the following steps: obtaining a compound of formula (III) from a compound of formula (II) through a Grignard reaction, oxidizing the compound of formula (III) to obtain a compound of formula (IV), and obtaining the compound of formula (I) from the compound of formula (IV) through a Fischer indole synthesis reaction. The preparation method is simple in operation, high in product yield and purity, and the prepared trans-decahydronaphthalene indole liquid crystal compound can be applied to special liquid crystal materials.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal material technology, and relates to a trans-decahydronaphthaleneindole liquid crystal compound and its preparation method. Background Technology

[0002] With the rapid development of liquid crystal displays (LCDs), increasingly higher demands are being placed on the performance of liquid crystal materials, such as operating temperature range, threshold voltage, birefringence, dielectric anisotropy, and response speed. Existing liquid crystal materials, with their monocyclic backbones (e.g., cyclohexane, benzene, and pyrimidine compounds), each possess unique photoelectric properties, but share a common drawback: a narrow liquid crystal phase range. This limitation is insufficient for high-end TFT (thin-film transistor) LCDs. Therefore, the search for novel liquid crystal compounds with superior molecular structures, wide phase transition temperature ranges, electrical anisotropy, and optical anisotropy has become a focus of attention for chemists. Summary of the Invention

[0003] The purpose of this invention is to provide a trans-decahydronaphthaleneindole liquid crystal compound and its preparation method. The compound is synthesized by Grignard, oxidation and Fischer indole processes, and the product has high yield and purity, and can be applied to special liquid crystal materials.

[0004] To achieve the technical objective of this invention, on one hand, this invention relates to a trans-decahydronaphthaleneindole liquid crystal compound having the chemical structural formula shown in formula (I):

[0005]

[0006] In compound (Ⅰ), F m The symbol indicates fluorine substitution, m indicates the number of fluorine substitutions, m can be 1 or 2, and R indicates a C3 to C7 straight-chain alkyl group.

[0007] On the other hand, the present invention relates to a method for preparing a trans-decahydronaphthaleneindole liquid crystal compound, comprising: obtaining compound (III) from compound (II) by Grignard reaction, obtaining compound (IV) from compound (III) by oxidation, and obtaining compound (I) from compound (IV) by Fischer indole synthesis reaction.

[0008] The specific structure of the compound is as follows:

[0009]

[0010] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds. The specific steps for obtaining compound (III) from compound (II) by Grignard reaction include: adding compound (II) to THF and stirring, cooling to 0 to -30°C, adding methyl Grignard reagent dropwise, acid destruction, and reacting for 0.5 to 2 hours to obtain compound (III).

[0011] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the methyl Grignard reagent is a bromomethyl Grignard reagent or a chloromethyl Grignard reagent; the molar ratio of the methyl Grignard reagent to the compound of formula (II) is 1 to 2:1.

[0012] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the acid is one of hydrochloric acid, sulfuric acid, and phosphoric acid, and the molar ratio of the acid to the methyl Grignard reagent is 1:1.

[0013] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the specific steps for oxidizing the compound of formula (III) to obtain the compound of formula (IV) include: mixing the compound of formula (III) with a solvent and an oxidant, and reacting at 40-80°C for 4-10 h to obtain the compound of formula (IV).

[0014] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the oxidant is CrO3 / H2SO4 or PCC.

[0015] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the solvent in the specific steps of oxidizing compound (III) to obtain compound (IV) is any one of chloroform, dichloroethane, chloroform and acetone.

[0016] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds. The specific steps for obtaining compound (I) from compound (IV) via Fischer indole synthesis reaction include: mixing compound (IV), fluorophenylhydrazine, acid and solvent, and reacting at 50-150°C for 5-10 h to obtain compound (I).

[0017] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the solvent in the specific steps of obtaining compound (I) from compound (IV) via Fischer indole synthesis reaction is DMSO or dioxane; furthermore, the acid is one of sulfuric acid, polyphosphoric acid and acetic acid.

[0018] Furthermore, the present invention provides a method for preparing trans-decahydronaphthaleneindole liquid crystal compounds, wherein the fluorophenylhydrazine is selected from:

[0019]

[0020] The molar ratio of the fluorophenylhydrazine to the compound of formula (Ⅳ) is 1:1.

[0021] On the other hand, the liquid crystal compound prepared by this invention has a novel molecular structure, a wide phase transition temperature range, and superior properties such as electrical anisotropy and optical anisotropy. Therefore, this invention seeks protection for the application of the liquid crystal compound in the field of liquid crystal materials.

[0022] Compared with the prior art, the present invention has the following beneficial effects or advantages:

[0023] This invention uses alkyl-trans-decahydronaphthalene-trans-cyclohexane-1-carboxaldehyde as raw material and carries out Grignard, oxidation, and Fischer-indole synthesis reactions to synthesize the compound. The operation is simple, and the product yield and purity are high. The compound is a nematic liquid crystal compound with excellent properties such as a wide phase transition temperature range, electrical anisotropy, and optical anisotropy, and can be used in special liquid crystal materials. Attached Figure Description

[0024] Figure 1 The H-NMR spectrum of the liquid crystal compound prepared in Example 1 is shown.

[0025] Figure 2 The H-NMR spectrum of the liquid crystal compound prepared in Example 2 is shown.

[0026] Figure 3 The H-NMR spectrum of the liquid crystal compound prepared in Example 3 is shown.

[0027] Figure 4 The image shows the differential scanning calorimetry curve of the liquid crystal compound prepared in Example 2.

[0028] Figure 5 The image shows the schlieren texture of the liquid crystal compound prepared in Example 2 at a temperature of 106°C.

[0029] Figure 6 The image shows the schlieren texture of the liquid crystal compound prepared in Example 2 at a temperature of 100°C. Detailed Implementation

[0030] The technical solution of the present invention will be described below with reference to the embodiments. However, the present invention is not limited to the following embodiments.

[0031] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0032] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0033] Example 1

[0034] This embodiment provides a method for preparing 4-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, the structural formula of which is shown below:

[0035]

[0036] 29 g of (1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphth-2-yl)cyclohexane-1-carboxaldehyde was added to 300 mL of THF, stirred, cooled to -10 °C, and 0.15 mol of bromomethyl Grignard reagent was added dropwise. After reacting for 1 h, 15 mL of hydrochloric acid was added, the mixture was concentrated, extracted with ethyl acrylate (EA), and recrystallized from concentrated ethanol to prepare 22.3 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphth-2-yl)cyclohexyl)ethane-1-ol, with a yield of 72.8% and a purity of 97.2%. (1R,4r)-4-

[0037] The structural formula of ((2R,4aS,6S,8aR)-6-propyldecahydronaphth-2-yl)cyclohexane-1-carboxaldehyde is as follows:

[0038]

[0039] 15.3 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol was added to 150 mL of acetone and 5 g of CrO3 / 5 g of sulfuric acid. The mixture was reacted at 55 °C for 5 h, extracted with EA, concentrated, and recrystallized to prepare 12.9 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol, with a yield of 84.9% and a purity of 98.3%. The structural formula of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol is as follows:

[0040]

[0041] Under nitrogen protection, 10 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one, 4.14 g of 4-fluorophenylhydrazine, and 10 ml of 50% concentrated sulfuric acid were added to 100 ml of dioxane. The mixture was stirred and reacted at 60 °C for 8 h. After the reaction was complete, the mixture was extracted with EA, concentrated, and recrystallized to prepare 8.56 g of 4-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, with a yield of 63.1% and a purity of 99.1%. ¹H-NMR is shown in [reference needed]. Figure 1 The characterization results are 1 H-NMR (500MHz, Chloroform-d) δ9.29 (s, 1H), 7.39 (ddd, J=7.2, 4.9, 2.3Hz, 2H), 7.0 9-7.02(m, 1H), 6.46-6.34(m, 1H), 3.02-2.94(m, 1H), 2.08-1.95(m, 2H), 1.88-1.77( m, 4H), 1.71 (ddt, J = 12.3, 7.9, 5.4 Hz, 2H), 1.66-1.58 (m, 1H), 1.58-1.53 ​​(m, 1H), 1.53-1.39 (m, 10H), 1.39-1.30 (m, 5H), 1.30-1.25 (m, 1H), 0.89 (td, J = 7.0, 1.5 Hz, 3H). The structural formula of 1-((1R, 4r)-4-((2R, 4aS, 6S, 8aR)-6-propyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one is as follows:

[0042]

[0043] Example 2

[0044] This embodiment provides a method for preparing 4,5-difluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, the structural formula of which is shown below:

[0045]

[0046] 31.8 g of (1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphth-2-yl)cyclohexyl-1-carboxaldehyde was added to 300 mL of THF, stirred, cooled to -20 °C, and 0.2 mol of bromomethyl Grignard reagent was added dropwise. After reacting for 3 h, 20 mL of hydrochloric acid was added, the mixture was concentrated, extracted with EA, and recrystallized from concentrated ethanol to prepare 25.0 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphth-2-yl)cyclohexyl)ethane-1-ol, with a yield of 75.0% and a purity of 97.7%. (1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphth-2-yl)cyclohexyl)ethane-1-ol was also prepared.

[0047] The structural formula of (-6-pentyldehydronaphth-2-yl)cyclohex-1-carboxaldehyde is as follows:

[0048]

[0049] 20.0 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol was added to 200 mL of dichloroethane and 26.2 g of PCC (pyridine chlorochromate). The mixture was reacted at 70 °C for 5 h, extracted with EA, concentrated, and recrystallized to prepare 15.8 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one, with a yield of 79.4% and a purity of 98.4%. The structural formula of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol is as follows:

[0050]

[0051] Under nitrogen protection, 10 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one, 4.33 g of 3,4-difluorophenylhydrazine, and 10 mL of 75% concentrated sulfuric acid were added to 100 mL of DMSO and stirred. The mixture was reacted at 100 °C for 8 h. After the reaction was complete, the mixture was extracted with EA, concentrated, and recrystallized to prepare 7.83 g of 3,4-difluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, with a yield of 59.3% and a purity of 99.2%. The 1H-NMR spectrum is shown in [reference needed]. Figure 2 The characterization results are 1H NMR (500MHz, Chloroform-d) δ9.44 (s, 1H) 7.62 (ddd, J=8.1, 5.0, 2.2Hz, 1H), 7.19 (dd, J=8.0, 5.0Hz, 1H), 6.41 (d, J=2.4Hz, 1H), 3.02-2.94 ( m, 1H), 2.05-1.97 (m, 1H), 1.88-1.77 (m, 4H), 1.71 (ddt, J=12.3, 7.9, 5.4Hz, 2H), 1.66-1.58 (m, 1H), 1.58-1.22 (m, 26H), 0.94-0.85 (m, 3H). The structural formula of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphth-2-yl)cyclohexyl)ethane-1-one is as follows:

[0052]

[0053] Example 3

[0054] This embodiment provides a method for preparing 4-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, the structural formula of which is shown below:

[0055]

[0056] 34.6 g of (1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphth-2-yl)cyclohexyl-1-carboxaldehyde was added to 300 mL of THF, stirred, cooled to -20 °C, and 0.1 mol of bromomethyl Grignard reagent was added dropwise. After reacting for 2 h, 20 mL of hydrochloric acid was added, the mixture was concentrated, extracted with EA, and recrystallized from concentrated ethanol to prepare 27.6 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphth-2-yl)cyclohexyl)ethane-1-ol, with a yield of 76.3% and a purity of 96.8%. (1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphth-2-yl)cyclohexyl)ethane-1-ol was also prepared.

[0057] The structural formula of (-6-heptayldecahydronaphth-2-yl)cyclohex-1-carboxaldehyde is as follows:

[0058]

[0059] 25.0 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol was added to 250 mL of dichloroethane and 14.8 g of PCC. The mixture was reacted at 80 °C for 5 h, extracted with EA, concentrated, and recrystallized to prepare 18.3 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one, with a yield of 73.4% and a purity of 97.4%. The structural formula of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-ol is as follows:

[0060]

[0061] Under nitrogen protection, 15 g of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)ethane-1-one, 5.3 g of 4-fluorophenylhydrazine, and 10 mL of 75% concentrated sulfuric acid were added to 100 mL of DMSO. The mixture was stirred and reacted at 100 °C for 8 h. After the reaction was complete, the mixture was extracted with EA, concentrated, and recrystallized to prepare 9.1 g of 4-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole, with a yield of 48.4% and a purity of 99.1%. The 1H-NMR spectrum is shown below. Figure 3 The characterization results are 1 H NMR (500MHz, Chloroform-d) δ9.29 (s, 1H), 7.39 (ddd, J=7.2, 5.0, 2.3Hz, 2H) ,7.09-7.02(m,1H),6.46-6.35(m,1H),3.02-2.94(m,1H),2.04-1.97(m,2H) ,1.88-1.77(m,4H),1.71(ddt,J=12.3,7.9,5.4Hz,2H),1.66-1.58(m,1H),1 .58-1.33(m, 15H), 1.33-1.27(m, 12H), 1.27-1.19(m, 2H), 0.94-0.85(m, 3H). The structural formula of 1-((1R,4r)-4-((2R,4aS,6S,8aR)-6-heptyldecahydronaphth-2-yl)cyclohexyl)ethane-1-one is as follows:

[0062]

[0063] The 5-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphthyl-2-yl)cyclohexyl)-1H-indole prepared in Example 2 was characterized for its properties and liquid crystal texture using a DSC-60 differential scanning calorimeter and an XPN-300E hot-stage polarizing microscope. Figure 4 It can be seen that the prepared 5-fluoro-2-((1R,4r)-4-((2R,4aS,6S,8aR)-6-pentyldecahydronaphth-2-yl)cyclohexyl)-1H-indole exhibits a liquid crystal phase during both heating and cooling processes. The liquid crystal phase range is: melting point: 77℃; clearing point: 127℃. Figure 5 The liquid crystal compound prepared in Example 2 is shown as a schlieren texture in its liquid crystal state at a temperature of 106°C. Figure 6 The image shows the schlieren texture of the liquid crystal compound prepared in Example 2 at 100°C. The liquid crystal compound prepared in this invention exhibits a typical nematic schlieren texture.

[0064] As described above, the present invention can be well implemented. The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, all changes and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the present invention.

Claims

1. A trans-decalin indole liquid crystal compound, having a chemical structure as shown in formula (I) : F represents a fluorine substitution, m represents the number of fluorine substitutions, m has a value of 1 or 2, and R is a C3-C7 straight chain alkyl group. m F represents a fluorine substitution, m represents the number of fluorine substitutions, m has a value of 1 or 2, and R is a C3-C7 straight chain alkyl group.

2. A method for preparing a trans-decacyclene indole liquid crystal compound, characterized by, comprising: The compound of formula (II) is obtained by Grignard reaction to obtain the compound of formula (III), the compound of formula (III) is oxidized to obtain the compound of formula (IV), and the compound of formula (I) is obtained by Fischer indole synthesis reaction of the compound of formula (IV) ; The specific structure of the compound is as follows:

3. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 2, characterized in that, The specific steps of obtaining the compound of formula (III) by Grignard reaction of the compound of formula (II) include: stirring the compound of formula (II) in THF, cooling to 0-30℃, adding methyl Grignard reagent dropwise, acid destruction, and reacting for 0.5-2h to obtain the compound of formula (III).

4. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 3, characterized in that, The methyl Grignard reagent is bromomethyl Grignard reagent or chloromethyl Grignard reagent; and the molar ratio of the methyl Grignard reagent to the compound of formula (II) is 1-2:

1.

5. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 3, characterized in that, The acid is one of hydrochloric acid, sulfuric acid and phosphoric acid, and the molar ratio of the acid to the methyl Grignard reagent is 1:

1.

6. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 2, characterized in that, The specific steps of obtaining the compound of formula (IV) by oxidizing the compound of formula (III) include: mixing the compound of formula (III) with a solvent and an oxidizing agent, and reacting at 40-80℃ for 4-10h to obtain the compound of formula (IV).

7. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 6, characterized in that, The oxidizing agent is a mixture of CrO3 and H2SO4 or PCC.

8. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 2, characterized in that, The specific steps of obtaining the compound of formula (I) by Fischer indole synthesis reaction of the compound of formula (IV) include: mixing the compound of formula (IV), fluorobenzene hydrazine, an acid and a solvent, and reacting at 50-150℃ for 5-10h to obtain the compound of formula (I).

9. The method for preparing the trans-decahydronaphthaleneindole liquid crystal compound according to claim 8, characterized in that, The fluorobenzene hydrazine is selected from: The molar ratio of the fluorobenzene hydrazine to the compound of formula (IV) is 1:

1. 10.The trans-decalin indole liquid crystal compound of claim 1 is applied in the field of liquid crystal materials.

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