Method for preparing a compound as a PI3K inhibitor and an intermediate compound for preparing the same

Abstract

The present invention provides a method for manufacturing a compound as a PI3K inhibitor that includes a process having a shortened reaction time in the process of manufacturing the compound as a PI3K inhibitor, enables the reaction under mild conditions, and reduces the number of process steps. Accordingly, the present invention provides a method for manufacturing a compound as a PI3K inhibitor that achieves process simplification compared to previously known manufacturing methods, while also being easy to control and easy to mass-produce industrially.

Description

Technology Field

[0001] The present invention relates to a method for preparing a compound as a PI3K inhibitor and an intermediate compound for preparing the same. Background Technology

[0002] Phosphatidylinositol 3-kinase (PI3 kinase; PI3K) is a lipid kinase that phosphorylates lipid molecules instead of proteins and plays an important role in cell survival, signal transduction, and the control of membrane trafficking. Problems with these regulations can lead to cancer, inflammatory diseases, and autoimmune diseases.

[0003] Recently, research results have been reported on the development of compounds with structures capable of selectively inhibiting PI3 kinase. These compounds as PI3K inhibitors can be usefully employed in the treatment of cancer, autoimmune diseases, and respiratory diseases. Therefore, simplifying the manufacturing process for compounds as PI3K inhibitors has emerged as an important issue. The problem to be solved

[0004] One objective of the present invention is to provide a new method for manufacturing a compound as a PI3K inhibitor that enables process simplification.

[0005] One objective of the present invention is to provide a method for preparing an intermediate compound for the preparation of a compound as a PI3K inhibitor that enables process simplification.

[0006] One objective of the present invention is to provide an intermediate compound for the preparation of a compound as a PI3K inhibitor that enables process simplification. means of solving the problem

[0007] To solve the above problem, the present invention provides a method for preparing a compound of Formula 7. The method for preparing a compound of Formula 7 comprises:

[0008] (S1) A step of preparing a compound of chemical formula 5 using a compound of chemical formula 4;

[0009] (S2) a step of preparing a compound of formula 6 by reacting a compound of formula 5 with dimethylformamide-dimethylacetal; and

[0010] (S3) The step of preparing a compound of chemical formula 7 by cyclizing a compound of chemical formula 6 may be included.

[0011] [Chemical Formula 4]

[0012]

[0013] [Chemical Formula 5]

[0014]

[0015] [Chemical Formula 6]

[0016]

[0017] [Chemical Formula 7]

[0018]

[0019] In the above chemical formulas 4 to 7, X1, X2, and X4 are each independently halogen atoms.

[0020] The above X1, X2, and X4 may be the same or different from each other. X1, X2, and X4 may each independently be F, Cl, Br, or I. More specifically, the above X1, X2, and X4 may each independently be Br or Cl. For example, X1, X2, and X4 may all be Cl. X1 and X4 may be Cl.

[0021] In the above chemical formula 6, either R1 or R2 is a hydrogen atom and the other is dimethylamine.

[0022] The method for preparing the compound of Formula 7 may further include the step of (S1-1) preparing the compound of Formula 4 by halogenating the compound of Formula 3.

[0023] [Chemical Formula 3]

[0024]

[0025] In the above chemical formula 3, X1 and X2 may be the same as those defined in the above chemical formulas 4 to 7.

[0026] The method for preparing the compound of Formula 7 may further include the step of (S1-2) reacting the compound of Formula 1 with the compound of Formula 2 to prepare the compound of Formula 3.

[0027] [Chemical Formula 1]

[0028]

[0029] [Chemical Formula 2]

[0030]

[0031] In the above Chemical Formulas 1 and 2, X1 and X2 may each independently be the same as those defined in Chemical Formulas 4 to 7. In Chemical Formula 2, X3 may be a halogen atom.

[0032] Unless otherwise specifically mentioned in this specification, the halogen atom may be any one selected from F, Cl, Br, or I. For example, it may be any one selected from Cl and Br.

[0033] The method for preparing the compound as a PI3K inhibitor may include the following steps (S1) to (S3).

[0034] (S1) A step of preparing a compound of chemical formula 5 by amination of a compound of chemical formula 4;

[0035] (S2) a step of preparing a compound of formula 6 by reacting a compound of formula 5 with dimethylformamide-dimethylacetal; and

[0036] (S3) A step of preparing a compound of chemical formula 7 by cyclizing a compound of chemical formula 6.

[0037] The method for preparing the compound as a PI3K inhibitor may further include the following step (S1-1).

[0038] (S1-1) A step of preparing a compound of chemical formula 4 by halogenating a compound of chemical formula 3.

[0039] The method for preparing the compound as a PI3K inhibitor may further include the following step (S1-2).

[0040] (S1-2) A step of preparing a compound of chemical formula 3 by reacting a compound of chemical formula 1 with a compound of chemical formula 2.

[0041] A method for preparing a compound of Formula 7 according to one embodiment is,

[0042] (S1-2) A step of preparing a compound of chemical formula 3 by reacting a compound of chemical formula 1 with a compound of chemical formula 2;

[0043] (S1-1) A step of preparing a compound of chemical formula 4 by halogenating a compound of chemical formula 3;

[0044] (S1) A step of preparing a compound of chemical formula 5 using a compound of chemical formula 4;

[0045] (S2) a step of preparing a compound of formula 6 by reacting a compound of formula 5 with dimethylformamide-dimethylacetal; and

[0046] (S3) The step of preparing a compound of formula 7 by cyclizing a compound of formula 6 may be included, and the same may apply to compounds of formulas 1 to 7 as long as there is no contradiction.

[0047] In addition, a method for preparing a compound of Formula 7 according to one embodiment is,

[0048] (S1-2) A step of preparing a compound of chemical formula 3 by reacting a compound of chemical formula 1 with a compound of chemical formula 2;

[0049] (S1-1) A step of preparing a compound of chemical formula 4 by halogenating a compound of chemical formula 3;

[0050] (S1) A step of preparing a compound of chemical formula 5 by amination of a compound of chemical formula 4;

[0051] (S2) a step of preparing a compound of formula 6 by reacting a compound of formula 5 with dimethylformamide-dimethylacetal; and

[0052] (S3) The step of preparing a compound of formula 7 by cyclizing a compound of formula 6 may be included, and the same may apply to compounds of formulas 1 to 7 as long as there is no contradiction.

[0053] Step (S1) above may be carried out in a polar aprotic solvent. For example, in Step (S1), the solvent may include dimethyl sulfoxide. Step (S1) above may be carried out under basic conditions. For example, in Step (S1), a basic compound such as ammonium hydroxide may participate in the reaction.

[0054] Step (S1-2) above may be carried out in a polar aprotic solvent. For example, in Step (S1-2), the solvent may include acetonitrile. Step (S1-2) above may be carried out under basic conditions. For example, in Step (S1-2), a basic compound may participate in the reaction. The basic compound may be a tertiary amine, such as triethylamine.

[0055] In this specification, polar aprotic solvents may include at least one of dichloromethane, tetrahydrofuran, ethyl acetate, dimethyl sulfoxide, dimethylformamide, and acetonitrile, but are not limited thereto.

[0056] In the above (S1-2) step, the equivalent ratio of the compound of Formula 1, the compound of Formula 2, and the triethylamine may be 1:1.1:1.5.

[0057] The above X1 and X2 may be Cl.

[0058] More specifically, the above (S1-2) step may include the steps of adding the compound of Formula 1 and the compound of Formula 2 to an organic solvent (e.g., a mixed solvent of acetonitrile and triethylamine) and refluxing and stirring for about 1 to 3 hours, cooling to room temperature, adding purified water and stirring at room temperature, filtering and washing (e.g., the washing solvent may be purified water), and drying.

[0059] The above step (S1-1) may be a step of reacting the compound of Formula 3 with N-chlorosuccinimide to carry out the chlorination reaction. In the step (S1-1), the equivalent ratio of the compound of Formula 3 to N-chlorosuccinimide may be 1:1.13.

[0060] The above step (S1-1) may be carried out in a polar aprotic solvent. More specifically, the above step (S1-1) may be carried out in at least one solvent selected from dichloromethane and acetonitrile.

[0061] More specifically, the above step (S1-1) may include the steps of adding the compound of Formula 3 and N-chlorosuccinimide to an organic solvent (e.g., dichloromethane) and refluxing and stirring for about 3 hours, cooling to room temperature and concentrating, adding an organic solvent (e.g., acetonitrile) and concentrating again, adding acetonitrile and cooling and stirring to about 0°C or higher and 5°C or lower, filtering and washing (the washing solvent may be an organic solvent, e.g., acetonitrile), and drying.

[0062] The above step (S1) may include a step of reacting the compound of Formula 4 with ammonium hydroxide (NH4OH) to produce a crude product of Formula 5. The above step (S1) may include a step of purifying the crude product.

[0063] The step of purifying the crude product may include at least one selected from ethanol, isopropyl alcohol, and acetone as a purification solvent. The step of purifying the crude product may use isopropyl alcohol as a purification solvent.

[0064] In the above step (S1), the equivalent ratio of the compound of formula 4 to ammonium hydroxide (NH4OH) may be 1:5 to 1:15.

[0065] More specifically, the step of producing the crude product in the above (S1) step may include the step of adding the compound of Formula 4 and the ammonium hydroxide (NH4OH) to an organic solvent (e.g., dimethyl sulfoxide) and stirring for about 3 hours (about 70°C to 90°C, e.g., about 80°C), stirring at room temperature for about 1 to 2 hours (or at least 2 hours until a solid is produced), adding purified water and stirring again at room temperature, filtering and washing (purified water may be used as the washing solvent), and drying.

[0066] More specifically, the step of purifying the crude product in step (S1) above may include adding an organic solvent (e.g., isopropyl alcohol) to the crude product and refluxing and stirring for about 30 minutes, stirring at room temperature for about 1 to 2 hours, filtering and washing (the washing solvent may be an organic solvent, e.g., isopropyl alcohol), and drying.

[0067] In step (S2) above, the equivalent ratio of the compound of formula 5 and the dimethylformamide-dimethylacetal may be 1:2.

[0068] More specifically, the above step (S2) may include the steps of refluxing and stirring the compound of Formula 5 and dimethylformamide-dimethylacetal in an organic solvent (e.g., dichloromethane) for about 1 hour, cooling and concentrating to room temperature, adding an organic solvent (e.g., isopropyl alcohol) and then refluxing and stirring, cooling and stirring to room temperature, filtering and washing (the washing solvent may be an organic solvent, e.g., isopropyl alcohol), and drying.

[0069] In the above step (S3), the cyclization reaction may include a step of reacting the compound of Formula 6 with a base and a step of adding an acid. The step of adding an acid may be performed after the step of reacting the compound of Formula 6 with the base. The base may be a tert-butoxide salt. For example, the base may be potassium tert-butoxide or sodium tert-butoxide. The acid may be an organic acid or an inorganic acid, for example, acetic acid or hydrochloric acid.

[0070] In step (S3) above, the equivalent ratio of the compound of Formula 6 to the base may be 1:1.5. The equivalent ratio of the compound of Formula 6 to the acid may be 1:3.

[0071] More specifically, the above step (S3) may include the steps of adding the compound of Formula 6 to an organic solvent (e.g., a mixed solvent of tetrahydrofuran and acetonitrile) and cooling and stirring at about -5°C, adding the base (e.g., about 2 to 3 times) and cooling and stirring for about 30 minutes to 2 hours, adding purified water and then adding an acid (e.g., acetic acid) dropwise to form a solid and stirring at room temperature for about 1 to 2 hours, filtering and washing (e.g., purified water may be used as the washing solvent), and drying.

[0072] In one embodiment, the method for preparing the compound of Formula 7 may further include the step of purifying the crude product of the compound of Formula 7.

[0073] In addition, the present invention may provide a method for preparing a compound of Formula 6. A method for preparing a compound of Formula 6 according to one embodiment may include the step of reacting a compound of Formula 5 with dimethylformamide-dimethylacetal.

[0074] [Chemical Formula 5]

[0075]

[0076] [Chemical Formula 6]

[0077]

[0078] In the above chemical formulas 5 and 6, X1 and X4 may each independently be halogen atoms. In the above chemical formula 6, either R1 or R2 may be a hydrogen atom and the other may be dimethylamine.

[0079] The method for preparing the compound of Formula 6 above can reduce the steps in the preparation process of the compound of Formula 7 and reduce the process time by providing the compound of Formula 6, which is an intermediate compound used in the preparation process of the compound of Formula 7 of the present invention.

[0080] A method for preparing a compound of Formula 7 according to one embodiment may include a step of cyclizing the compound of Formula 6 described above.

[0081] According to one embodiment of the present invention, a compound represented by the following chemical formula 6 may be provided.

[0082] [Chemical Formula 6]

[0083]

[0084] In the above chemical formula 6, X1 and X4 may each independently be halogen atoms. Either R1 or R2 may be a hydrogen atom and the other may be dimethylamine.

[0085] The compound represented by the above chemical formula 6 can participate as an intermediate compound in the manufacturing process of the compound as a PI3K inhibitor of one embodiment, thereby reducing process steps and process costs.

[0086] According to the present invention, unlike conventional methods for manufacturing compounds as PI3K inhibitors, the process steps required for manufacturing compounds as PI3K inhibitors can be reduced, and the synthesis of compounds as PI3K inhibitors is possible without long-duration reflux and stirring reactions that take several days or more. In addition, since the reaction can be carried out under mild reaction conditions, risk factors that may occur during synthesis can be significantly reduced, and the manufacturing process can be easily managed.

[0087] Therefore, process simplification is achieved, which shortens the time required for the process, reduces process costs, and facilitates process management. Accordingly, the method for preparing a compound as a PI3K inhibitor according to one embodiment may be suitable for the industrial production of a compound as a PI3K inhibitor. Effects of the invention

[0088] According to the method for preparing a compound as a PI3K inhibitor of the present invention, the manufacturing process of the compound as a PI3K inhibitor is simplified, thereby enabling a reduction in manufacturing steps and manufacturing costs. In addition, the intermediate compound for preparing the compound as a PI3K inhibitor according to the present invention can be used in the manufacturing process of the compound as a PI3K inhibitor to reduce manufacturing steps and manufacturing costs. Accordingly, the productivity of the compound as a PI3K inhibitor can be improved. Specific details for implementing the invention

[0089] Hereinafter, the advantages and features of the present invention and the methods for achieving them will be described in detail with reference to the following embodiments. However, the present invention is not limited to the embodiments disclosed below and may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the claims.

[0090] Example 1: Synthesis of (S)-4-((1-(4,8-dichloro-1-oxo-2-phenyl-1,2-dihydroisoquinolin-3-yl)ethyl)amino)pyrido[2,3-d]pyrimidin-5(8H)-one

[0091] 1. Reaction equation

[0092]

[0093] 2. Step (1) - Synthesis of intermediate compound QHK

[0094] According to the above reaction scheme, acetonitrile (AN) (80 ml), DCK (1-(4,6-dichloropyrimidin-5-yl)ethanone) (7.0 g, 36.8 mmol), and triethylamine (Et) were added to the intermediate compound IQA ((S)-3-(1-aminoethyl)-8-chloro-2-phenylisoquinolin-1(2H)-one) (10 g, 33.5 mmol). 3-N) (7.0 ml, 50.2 mmol) was added and refluxed and stirred for 3 hours. After cooling to room temperature (25°C), purified water (20 ml) was added and stirred at room temperature (25°C). The solid was filtered, washed with purified water (25 ml), and dried with hot air at 40°C to obtain the intermediate compound QHK((S)-3-(1-((5-acetyl-6-chloropyrimidin-4-yl)amino)ethyl)-8-chloro-2-phenylisoquinolin-1(2H)-one). (13.8 g, yield: 91%)

[0095] 1 H-NMR (400MHz, CDCl3): δ 1.43 (d, 3H), δ 2.78 (s, 3H), δ 4.92 (t, 1H) δ 6.48 (s, 1H), δ 7.26-7.46 (m, 8H), δ 8.18 (s, 1H), δ 8.97 (d, 1H).

[0096] 3. Step (2) - Synthesis of the intermediate compound IQCK

[0097] Dichloromethane (MC) (35 ml) and N-chlorosuccinimide (NCS) (2.0 g, 15 mmol) were added to the intermediate compound QHK (6.0 g, 13 mmol) obtained in step (1) above, and the mixture was refluxed and stirred for 3 hours. After cooling to room temperature (25 °C), the reaction mixture was concentrated under reduced pressure. Acetonitrile (18 ml) was added to the concentrated residue and stirred at 0 to 5 °C for 1 hour, after which the solid was filtered, washed with acetonitrile (6 ml), and dried with hot air at 40 °C to obtain the intermediate compound IQCK ((S)-3-(1-((5-acetyl-6-chloropyrimidin-4-yl)amino)ethyl)-4,8-dichloro-2-phenylisoquinolin-1(2H)-one). (5.7g, Yield: 89%)

[0098] 1H-NMR (400MHz, CDCl3): δ 1.62 (d, 3H), δ 2.74 (s, 3H), δ 4.98 (t, 1H), δ 7.17-7.95 (m, 8H), δ 8.26 (s, 1H), δ 9.37 (broad, 1H)

[0099] 4. Step (3) - Synthesis of the intermediate compound IQNK

[0100] Dimethyl sulfoxide (DMSO) (304 ml) and ammonium hydroxide (48.6 ml, 642 mmol) were added to the intermediate compound IQCK (30.4 g, 62 mmol) obtained in step (2) above, heated and stirred at 80°C for 5 hours, then cooled to room temperature and stirred overnight. Purified water (304 ml) was added to the reaction mixture from which a solid was formed, and stirred at room temperature for 1.5 hours. The solid of the reaction mixture was filtered, washed with purified water (610 ml), and dried with hot air at 40°C to obtain a crude product of IQCK (29.8 g). The crude product of IQCK (29.8 g) was added to isopropyl alcohol (300 ml) and refluxed for 10 minutes, then cooled to room temperature and stirred for 2 hours. The solid was filtered, washed with isopropyl alcohol (75 ml), and dried with hot air at 40°C to obtain purified IQNK ((S)-3-(1-((5-acetyl-6-aminopyrimidin-4-yl)amino)ethyl)-4,8-dichloro-2-phenylisoquinolin-1(2H)-one). (26.9 g, yield 92%)

[0101] 1 H-NMR (400MHz, CDCl3): δ 1.60 (d, 3H), δ 2.56 (s, 3H), δ 5.03 (t, 1H), δ 5.77 (br, 2H), δ 7.15-7.97 (m, 9H)

[0102] In step (3), isopropyl alcohol was used as the purification solvent for the crude product of IQNK, but the example is not limited thereto and various organic solvents can be used. For example, one or more organic solvents selected from ethanol, isopropyl alcohol, and acetone may be used. Preferably, isopropyl alcohol may be used as the solvent.

[0103] 5. Step (4) - Synthesis of intermediate compound IQVK

[0104] Dichloromethane (130 ml) and dimethylformamide-dimethylacetal (DMF-DMA) (15.2 ml, 114.4 mmol) were added to the intermediate compound IQNK (26.8 g, 57.2 mmol) obtained in step (3) above, and the mixture was refluxed and stirred for 1 hour, then cooled to room temperature (25°C) and concentrated under reduced pressure. Isopropyl alcohol (190 ml) was added to the concentrated residue, the mixture was refluxed and stirred, and then cooled to room temperature and the solid was filtered. The filtered solid was washed with isopropyl alcohol (80 ml) and dried with hot air at 40°C to obtain the intermediate compound IQVK((S)-N'-(5-acetyl-6-((1-(4,8-dichloro-1-oxo-2-phenyl-1,2-dihydroisoquinolin-3-yl)ethyl)amino)pyrimidin-4-yl)-N,N-dimethylformimidamide). (26.2 g, yield: 88%)

[0105] 1 H-NMR (400MHz, CDCl3): δ 1.60 (d, 3H), δ 2.75 (s, 3H), δ 3.11 (s, 3H), δ 3.14 (s, 3H), δ 4.99 (t, 1H), δ 7.26-7.96 (m, 8H), δ 8.10 (s, 1H), δ 8.55 (s, 1H)

[0106] 6. Step (5) - Synthesis of the final product

[0107] Tetrahydrofuran (6 ml) was added to the intermediate compound IQVK (1 g, 1.9 mmol) obtained in step (4) above, and the mixture was cooled and stirred at -5°C. Potassium tert-butoxide (0.32 g, 2.9 mmol) was added in three separate additions and stirred while maintaining the temperature at -5°C for 0.5 hours, then purified water (12 ml) was added, followed by acetic acid (0.33 ml, 5.7 mmol), and the mixture was stirred at room temperature for 2 hours. The resulting solid was filtered and washed with purified water (10 ml), then dried with hot air at 40°C to obtain the final product ((S)-4-((1-(4,8-dichloro-1-oxo-2-phenyl-1,2-dihydroisoquinolin-3-yl)ethyl)amino)pyrido[2,3-d]pyrimidin-5(8H)-one) (0.85 g, yield: 77%).

[0108] 1 H-NMR (400MHz, CDCl3): δ 1.67 (d, 3H), δ 5.03 (t, 1H), δ 6.31 (d, 1H), δ 7.20-7.95 (m, 9H), δ 8.25 (s, 1H)

[0109] Referring to Example 1, the method for preparing a compound as a PI3K inhibitor according to one embodiment can synthesize the compound as a PI3K inhibitor in only five steps, from step (1) to step (5). In addition, since the reaction time for each step is short, the process time can be shortened. More specifically, steps (1) to (5) do not involve harsh reaction conditions requiring reflux and stirring for several days or more. In particular, steps (1) to (5) include a reflux and stirring step of about 1 to about 5 hours, and do not include a reflux and stirring step that requires more time. Therefore, according to the method for preparing a compound as a PI3K inhibitor of one embodiment, the total number of working days can be shortened by several days or more. In addition, since strong acids such as TFA (Trifluoroacetic acid) or MsOH (Methane Sulfonic Acid) are not used, the reaction can proceed under mild reaction conditions. Therefore, risk factors that may occur during synthesis can be significantly reduced, and manufacturing process control can be facilitated.

[0110] A method for manufacturing a PI3K inhibitor according to one embodiment simplifies the process by manufacturing the PI3K inhibitor using a method comprising steps (S1) to (S5), thereby reducing the number of manufacturing steps and manufacturing costs. Additionally, manufacturing the PI3K inhibitor under mild reaction conditions can facilitate process management.

Claims

Claim 1 (S1) a step of preparing a compound of Formula 5 using a compound of Formula 4; (S2) a step of preparing a compound of Formula 6 by reacting the compound of Formula 5 with dimethylformamide-dimethylacetal; and (S3) a step of preparing a compound of Formula 7 by cyclizing the compound of Formula 6; wherein steps (S1) and (S2) are carried out in a polar aprotic solvent, a method for preparing a compound of Formula 7: [Formula 4] [Chemical Formula 5] [Chemical Formula 6] [Chemical Formula 7] In the above chemical formulas 4 to 7, X1, X2 and X4 are each independently halogen atoms, and in the above chemical formula 6, either R1 or R2 is a hydrogen atom and the other is dimethylamine. Claim 2 A method for preparing a compound of Formula 7 according to claim 1, wherein the manufacturing method further comprises the step of (S1-1) preparing a compound of Formula 4 by halogenating a compound of Formula 3: [Formula 3] In the above chemical formula 3, X1 and X2 are each independently identical to those defined in the above chemical formulas 4 to 7. Claim 3 In claim 2, the above manufacturing method further comprises the step of (S1-2) reacting a compound of Formula 1 with a compound of Formula 2 to produce a compound of Formula 3, wherein a method for producing a compound of Formula 7 [Formula 1] [Chemical Formula 2] In the above chemical formulas 1 and 2, X1 and X2 are each independently identical to those defined in the above chemical formulas 4 to 7, and in the above chemical formula 2, X3 is a halogen atom. Claim 4 A method for preparing a compound of Formula 7, wherein, in claim 1, the step (S1) is carried out under basic conditions. Claim 5 A method for preparing a compound of Formula 7, wherein, in claim 1, the polar aprotic solvent in step (S1) is dimethyl sulfoxide and the polar aprotic solvent in step (S2) is dichloromethane. Claim 6 A method for preparing a compound of Formula 7, wherein the step (S1-1) above is a step of reacting the compound of Formula 3 with N-chlorosuccinimide to chlorine it. Claim 7 A method for preparing a compound of Formula 7 according to claim 1, wherein step (S1) comprises the step of reacting the compound of Formula 4 with ammonium hydroxide to produce a crude product of Formula 5. Claim 8 In claim 7, the above (S1) step comprises a step of purifying the crude product, a method for preparing a compound of Formula 7. Claim 9 In claim 8, the step of purifying the crude product comprises at least one selected from ethanol, isopropyl alcohol, and acetone as a purification solvent, in a method for preparing a compound of Formula 7. Claim 10 In claim 8, the step of purifying the crude product is a method for preparing a compound of Formula 7 using isopropyl alcohol as a purification solvent. Claim 11 A method for preparing a compound of Formula 7, wherein in the step (S3), the cyclization reaction comprises the step of reacting the compound of Formula 6 with a base and the step of adding an acid. Claim 12 In claim 11, a method for preparing a compound of formula 7 in which the base is a tert-butoxide salt. Claim 13 A method for preparing a compound of Formula 7, wherein, in Clause 11, the acid is acetic acid or hydrochloric acid. Claim 14 A method for preparing a compound of Formula 6 comprising the step of reacting a compound of Formula 5 with dimethylformamide-dimethylacetal in a polar aprotic solvent: [Formula 5] [Chemical Formula 6] In the above chemical formulas 5 and 6, X1 and X4 are each independently halogen atoms, and in the above chemical formula 6, either R1 or R2 is a hydrogen atom and the other is dimethylamine. Claim 15 A method for preparing a compound of Formula 7 comprising the step of cyclizing a compound of Formula 6: [Formula 6] [Chemical Formula 7] In the above chemical formulas 6 and 7, X1 and X4 are each independently halogen atoms, and in the above chemical formula 6, either R1 or R2 is a hydrogen atom and the other is dimethylamine. Claim 16 Compound represented by the following chemical formula 6: [Chemical Formula 6] In the above chemical formula 6, X1 and X4 are each independently halogen atoms, and either R1 or R2 is a hydrogen atom and the other is dimethylamine.

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