Pyridine derivative and preparation method and application thereof, Tau protein aggregate probe and preparation method and application thereof

Abstract

The invention provides a pyridine derivative and a preparation method and application thereof, a Tau protein aggregate probe and a preparation method and application thereof, and relates to the technical field of ligands of protein aggregates. The pyridine derivative provided by the invention has an indole combined quinoline structure, has high selectivity, high specificity and high affinity to Tau protein, can be used as a selective ligand of a Tau protein aggregate, provides a diagnostic tool and a treatment strategy for neurodegenerative diseases such as Alzheimer's disease, and has broad application prospects. The method has potential value for early diagnosis, disease progress monitoring and treatment effect evaluation of neurodegenerative diseases.

Description

Technical Field

[0001] The present invention relates to the technical field of ligands of protein aggregates, and particularly relates to a pyridine derivative, a preparation method and application thereof, a Tau protein aggregate probe, and a preparation method and application thereof. Background Art

[0002] Tau protein is a microtubule-associated protein mainly expressed in neurons and plays a crucial role in maintaining the stability of the cytoskeleton. In Alzheimer's disease (AD) and other neurodegenerative diseases, abnormal aggregation of Tau protein forms neurofibrillary tangles (NFTs), which is one of the key pathological features of these diseases. With the progression of the disease, abnormal aggregation of Tau protein is closely related to cognitive decline.

[0003] Positron emission tomography (PET) is a non-invasive imaging technique that can detect and quantify the distribution of biomolecules in the body and is of great significance for studying neurodegenerative diseases. The research on Tau PET imaging agents for the characteristic pathological changes of AD can improve the early diagnosis of AD, especially the detection rate of patients with mild cognitive impairment, and is also of great significance for evaluating the efficacy of drugs for treating AD. In recent years, with the continuous in-depth research on the pathogenesis of AD, PHFs Tau (paired helical filaments in neurofibrillary tangles composed of hyperphosphorylated Tau protein) has gradually attracted attention. The research on PET imaging agents for PHFs Tau has also increased accordingly and has made great progress. Currently, a variety of Tau PET imaging agents have been reported, such as 18 F-AV-1415, 18 F-GTP1, 18 F-MK-6240, 18 F-THK5351, 18 F-RO695894 and 18 F-THK-5117, etc. Among them, 18 F-AV-1451 achieved the following two main results in phase III clinical trials: detecting brain Tau protein pathology and diagnosing AD, and was approved by the US FDA for marketing on May 28, 2020, under the trade name Tauvid. However, the selectivity of Tauvid for Tau protein still needs to be improved. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a pyridine derivative, a preparation method and application thereof, a Tau protein aggregate probe, and a preparation method and application thereof. The pyridine derivative provided by the present invention has high selectivity for Tau protein.

[0005] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0006] The present invention provides a pyridine derivative having a structure shown in Formula I:

[0007]

[0008] Wherein, X is carbon and hydrogen or nitrogen, Y is carbon and hydrogen or nitrogen, and R1 is halogen or hydrogen;

[0009] R2 is R3 is halogen or hydrogen.

[0010] Preferably, the pyridine derivative has any one of the structures shown in I1 to I10:

[0011]

[0012] The present invention also provides a preparation method of the pyridine derivative described in the above technical solution, including the following steps: mixing compound a, compound b, a basic reagent, a coupling catalyst and an organic solvent, and performing a coupling reaction to obtain the pyridine derivative;

[0013] The structural formula of the compound b is as follows:

[0014] The structural formula of the compound a is as follows:

[0015] Preferably, the molar ratio of the compound a to the compound b is 1:0.5 to 1.5;

[0016] The basic reagent includes one or more of alkali metal alcoholates, alkali metal hydrides, organo-alkali metal compounds and alkali metal hydroxides; the molar ratio of the compound a to the basic reagent is 1:0.5 to 5;

[0017] The coupling catalyst preferably includes one or more of (2 - Di - tert - butylphosphino - 2',4',6' - triisopropyl - 1,1' - biphenyl)(2' - amino - 1,1' - biphenyl - 2 - yl)palladium(II) methanesulfonate (tBuXPhos - Pd - G3), dichloro[2 - (di - tert - butylphosphino)-2',4',6' - triisopropyl - 1,1' - biphenyl][2 - (2 - aminoethyl)phenyl]palladium(II), (2 - Di - tert - butylphosphino - 2',4',6' - triisopropylbiphenyl)(2' - methylamino - 1,1' - biphenyl - 2 - yl)palladium(II) methanesulfonate, [n - butyldi(1 - adamantyl)phosphine](2' - methylamino - 1,1' - biphenyl - 2 - yl)palladium(II) methanesulfonate, (2 - Dicyclohexylphosphino - 2',4',6' - tri - isopropyl - 1,1' - biphenyl)(2' - amino - 1,1' - biphenyl - 2 - yl)palladium(II) methanesulfonate, and (2 - Dicyclohexylphosphino - 2',6' - diisopropoxy - 1,1' - biphenyl)(2 - amino - 1,1' - biphenyl - 2 - yl)palladium(II) methanesulfonate; the molar ratio of the compound a to the coupling catalyst is 1:0.01 - 0.1.

[0018] Preferably, the organic solvent includes one or more of tetrahydrofuran, N,N - dimethylformamide, 1,4 - dioxane, acetonitrile, and dimethyl sulfoxide.

[0019] Preferably, the temperature of the coupling reaction is 60 - 80 °C and the time is 12 - 24 h.

[0020] The present invention also provides the use of the pyridine derivative described in the above technical solution as a protein aggregate ligand.

[0021] Preferably, the protein aggregate includes Tau protein aggregate.

[0022] The present invention also provides a diagnostic drug, which includes the pyridine derivative described in the above technical solution, and the pyridine derivative contains a radioactive halogen.

[0023] The present invention also provides the use of the pyridine derivative or the diagnostic drug described in the above technical solution in the preparation of a drug for diagnosing neurodegenerative diseases.

[0024] The pyridine derivative having the structure shown in Formula I provided by the present invention has an indole - binding quinoline structure, has high selectivity, high specificity, and high affinity for Tau protein, can be used as a selective ligand for Tau protein aggregates, provides a diagnostic tool and a treatment strategy for neurodegenerative diseases such as Alzheimer's disease, and has potential value for the early diagnosis, disease progression monitoring, and treatment effect evaluation of neurodegenerative diseases.

[0025] The preparation method provided by the present invention has a simple process, is easy to operate, has low production costs, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1H NMR spectrum of compound I1 in Example 1;

[0027] Figure 2 1H NMR spectrum of compound I2 in Example 2;

[0028] Figure 3 1H NMR spectrum of compound I3 in Example 3;

[0029] Figure 4 1H NMR spectrum of compound I4 in Example 4;

[0030] Figure 5 1H NMR spectrum of compound I5 in Example 5;

[0031] Figure 6 1H NMR spectrum of compound I6 in Example 6;

[0032] Figure 7 1H NMR spectrum of compound I7 in Example 7;

[0033] Figure 8 1H NMR spectrum of compound I8 in Example 8;

[0034] Figure 9 1H NMR spectrum of compound I9 in Example 9;

[0035] Figure 10 1H NMR spectrum of compound I10 in Example 10. DETAILED DESCRIPTION OF THE INVENTION

[0036] The present invention provides a pyridine derivative having the structure shown in Formula I:

[0037]

[0038] wherein X is CH or N, Y is CH or N, and R1 is halogen or H;

[0039] R2 is or R3 is halogen or H.

[0040] In the present invention, the halogen in R1 and R3 independently preferably includes fluorine, chlorine, bromine or iodine, more preferably fluorine.

[0041] In the present invention, the pyridine derivative preferably has any one of the structures shown in I1-I10, as shown in Table 1:

[0042] Table 1 Pyridine Derivatives

[0043]

[0044]

[0045] The present invention also provides a method for preparing the pyridine derivatives described in the above technical solution, comprising the following steps: mixing compound a, compound b, a basic reagent, a coupling catalyst, and an organic solvent, and performing a coupling reaction to obtain the pyridine derivatives;

[0046] The structural formula of the said compound b is as follows:

[0047] The structural formula of the said compound a is as follows:

[0048] Wherein, the definitions of X, Y, R1, and R3 are the same as those of X, Y, R1, and R3 in the said formula I.

[0049] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0050] In the present invention, the molar ratio of the said compound a to compound b is preferably 1:0.5 to 1.5, and in specific embodiments, it can be 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5.

[0051] In the present invention, the said compound a preferably includes 2-bromo-4-fluoropyridine, 4-bromo-2-fluoropyridine, 3-bromo-6-fluoroisoquinoline, 1-bromoisoquinoline, 7-bromoisoquinoline, or 5-bromoisoquinoline.

[0052] In the present invention, the said compound b preferably includes 5-azabenzimidazole, 6-azaindole, benzimidazole, indole, or 6-fluoroindole.

[0053] In the present invention, the basic reagent preferably includes one or more of alkali metal alcoholates, alkali metal hydrides, organo-alkali metal compounds, and alkali metal hydroxides; the alkali metal alcoholates preferably include one or more of sodium tert-butoxide, potassium tert-butoxide, sodium ethoxide, and potassium ethoxide; the alkali metal hydrides preferably include sodium hydride and / or potassium hydride; the organo-alkali metal compounds preferably include lithium diisopropylamide and / or lithium bis(trimethylsilyl)amide; the alkali metal hydroxides preferably include sodium hydroxide and / or potassium hydroxide. In the present invention, the molar ratio of compound a to the basic reagent is preferably 1:0.5 to 5, and in specific embodiments, it can be 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5.

[0054] In the present invention, the coupling catalyst preferably includes one or more of (2-tert-butylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate (tBuXPhos-Pd-G3), chloro[2-(di-tert-butylphosphino)-2',4',6'-triisopropyl-1,1'-biphenyl][2-(2-aminoethyl)phenyl)]palladium(II), (2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl)(2'-methylamino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate, [n-butyldi(1-adamantyl)phosphine](2'-methylamino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate, (2-dicyclohexylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate, and (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II) methanesulfonate; in the present invention, the molar ratio of compound a to the coupling catalyst is preferably 1:0.01 to 0.1, and in specific embodiments, it can be 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, or 1:0.1.

[0055] In the present invention, the organic solvent preferably includes one or more of tetrahydrofuran, N,N-dimethylformamide, 1,4-dioxane, acetonitrile, and dimethyl sulfoxide; the organic solvent is preferably an anhydrous organic solvent. In the present invention, the mass ratio of the compound a to the volume of the organic solvent is preferably 1 g: 50 - 500 mL, and in specific embodiments, it can be 1 g: 50 mL, 1 g: 100 mL, 1 g: 150 mL, 1 g: 200 mL, 1 g: 250 mL, 1 g: 300 mL, 1 g: 350 mL, 1 g: 400 mL, 1 g: 450 mL, or 1 g: 500 mL.

[0056] In the present invention, the mixing preferably includes: dissolving the compound a and the compound b in an organic solvent, and adding a basic reagent and a coupling catalyst under stirring conditions for mixing.

[0057] In the present invention, the temperature of the coupling reaction is preferably 60 - 80 °C, and in specific embodiments, it can be 60 °C, 65 °C, 68 °C, 70 °C, 75 °C, or 80 °C; the time of the coupling reaction is preferably 12 - 24 h, and in specific embodiments, it can be 12 h, 15 h, 18 h, 20 h, 22 h, or 24 h; the coupling reaction is preferably carried out under a protective atmosphere, and the protective atmosphere preferably includes nitrogen, argon, or helium.

[0058] After completing the coupling reaction, the present invention preferably further includes: concentrating the reaction solution obtained from the coupling reaction under reduced pressure to remove the reaction solvent, dissolving it in an organic solvent, washing with saturated brine, and separating and purifying it by silica gel column chromatography to obtain the pyridine derivative. In the present invention, the organic solvent for dissolution preferably includes one or more of ethyl acetate, dichloromethane, ether, petroleum ether, and methyl tert-butyl ether; the mass ratio of the compound a to the volume of the organic solvent for dissolution is preferably 1 g: 50 - 500 mL, and in specific embodiments, it can be 1 g: 50 mL, 1 g: 100 mL, 1 g: 200 mL, 1 g: 300 mL, 1 g: 400 mL, or 1 g: 500 mL. In the present invention, the number of times of washing with saturated brine is preferably 2 - 5 times, more preferably 3 - 4 times; the mass ratio of the compound a to the volume of the saturated brine for single washing is preferably 1 g: 100 - 500 mL, and in specific embodiments, it can be 1 g: 100 mL, 1 g: 200 mL, 1 g: 300 mL, 1 g: 400 mL, or 1 g: 500 mL. In the present invention, the eluent used for silica gel column chromatography separation and purification is preferably a dichloromethane-methanol mixed solvent, and the volume ratio of dichloromethane to methanol in the dichloromethane-methanol mixed solvent is preferably 10 - 50:1, and in specific embodiments, it can be 10:1, 20:1, 30:1, 40:1, or 50:1.

[0059] The present invention also provides the use of the pyridine derivatives described in the above technical solution as protein aggregate ligands. In the present invention, the protein aggregates preferably include Tau protein aggregates.

[0060] The present invention also provides a diagnostic drug, comprising the pyridine derivatives described in the above technical solution, wherein the pyridine derivatives contain radioactive halogens, and the radioactive halogens preferably include 18 F and / or 125 I.

[0061] The present invention also provides the use of the pyridine derivatives or diagnostic drugs described in the above technical solution in the preparation of drugs for diagnosing neurodegenerative diseases. In the present invention, the drugs for diagnosing neurodegenerative diseases preferably include TauPET imaging agents or Tau protein tracers.

[0062] To further illustrate the present invention, the pyridine derivatives provided by the present invention, their preparation methods and applications, Tau protein aggregate probes, their preparation methods and applications will be described in detail below in conjunction with examples, but they should not be construed as limiting the protection scope of the present invention.

[0063] Example 1

[0064]

[0065] Dissolve 2-bromo-4-fluoropyridine (100 mg, 1.0 eq) and 5-azabenzimidazole (154 mg, 1.0 eq) in 10 mL of anhydrous tetrahydrofuran solution, add sodium tert-butoxide (246 mg, 3.0 eq) under stirring, and (2'-amino-1,1'-biphenyl-2-yl)palladium(II) (tBuXPhos-Pd-G3, 40 mg, 0.05 eq) of methanesulfonic acid (2-di-tert-butylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl). React at 68 °C for 16 h under nitrogen protection. After the reaction is completed, concentrate under reduced pressure to remove the reaction solvent, add 40 mL of ethyl acetate to dissolve the crude product, wash with saturated brine 3 times (20 mL each time), combine the organic layers, and separate and purify by silica gel chromatography column (eluent: dichloromethane:methanol volume ratio = 20:1) to obtain pyridine derivative (I1).

[0066] Compound I1: 23 mg of yellow solid, yield 13%, HPLC purity = 95.90%. Figure 1 For the nuclear magnetic resonance hydrogen spectrum of compound I1, 11H NMR (400 MHz, DMSO-d6) δ 9.72 (s, 1H), 9.26 (s, 1H), 8.72 (dd, J = 8.8, 5.7 Hz, 1H), 8.49 (d, J = 5.5 Hz, 1H), 8.11 (dd, J = 10.6, 2.1 Hz, 1H), 7.82 (d, J = 5.4 Hz, 1H), 7.44 (ddd, J = 8.1, 5.8, 2.2 Hz, 1H).

[0067] Example 2

[0068]

[0069] The method for preparing I2 by reacting 4-bromo-2-fluoropyridine (100 mg, 1.0 eq) with 5-azabenzimidazole (1.0 eq) was the same as that in Example 1.

[0070] Compound I2: 25 mg of pale yellow solid, yield 14%, HPLC purity = 99.89%. Figure 2 This is the 1H nuclear magnetic resonance spectrum of compound I2. 1 1H NMR (400 MHz, DMSO-d6) δ 9.15 (s, 1H), 9.08 (s, 1H), 8.70 (dd, J = 8.8, 5.7 Hz, 1H), 8.51 (d, J = 5.6 Hz, 1H), 8.32 (d, J = 5.6 Hz, 1H), 8.06 (dd, J = 10.5, 2.1 Hz, 1H), 7.44 (ddd, J = 8.2, 5.7, 2.2 Hz, 1H).

[0071] Example 3

[0072]

[0073] The method for preparing I3 by reacting 4-bromo-2-fluoropyridine (100 mg, 1.0 eq) with 6-azaindole (1.0 eq) was the same as that in Example 1.

[0074] Compound I3: 41 mg of white solid, yield 26%, HPLC purity = 99.47%. Figure 3 This is the 1H nuclear magnetic resonance spectrum of compound I3. 1 1H NMR (400 MHz, DMSO-d6) δ 9.20 (s, 1H), 8.59 (d, J = 5.5 Hz, 1H), 8.38 (d, J = 5.3 Hz, 1H), 8.19 (d, J = 3.4 Hz, 1H), 8.11 (d, J = 1.8 Hz, 1H), 7.97 (dd, J = 5.5, 1.9 Hz, 1H), 7.75 (d, J = 5.3 Hz, 1H), 6.95 (d, J = 3.3 Hz, 1H).

[0075] Example 4

[0076]

[0077] The method for preparing I by reacting 2-bromo-4-fluoropyridine (100 mg, 1.0 eq) with benzimidazole (1.0 eq) is the same as that in Example 1.

[0078] Compound I4: 53 mg of pale yellow solid, yield 30%, HPLC purity = 97.93%. Figure 4 This is the 1H NMR spectrum of Compound I4. 1 H NMR (400 MHz, DMSO-d6) δ 9.03 (s, 1H), 8.53 (d, J = 5.4 Hz, 1H), 8.34 (dd, J = 14.9, 4.4 Hz, 2H), 7.77 (d, J = 7.3 Hz, 1H), 7.69 (dd, J = 5.3, 1.5 Hz, 1H), 7.48 - 7.27 (m, 2H).

[0079] Example 5

[0080]

[0081] The preparation method of 4-bromo-2-fluoropyridine (100 mg, 1.0 eq) and benzimidazole (1.0 eq) is the same as that in Example 1.

[0082] Compound I5: 49 mg of yellow solid, yield 27%, HPLC purity = 99.90%. Figure 5 This is the 1H NMR spectrum of Compound I5. 1 H NMR (400 MHz, DMSO-d6) δ 9.03 (s, 1H), 8.52 (d, J = 5.4 Hz, 1H), 8.41 - 8.28 (m, 2H), 7.82 - 7.73 (m, 1H), 7.68 (dd, J = 5.4, 1.6 Hz, 1H), 7.45 - 7.29 (m, 2H).

[0083] Example 6

[0084]

[0085] The method for preparing I6 by reacting 2-bromo-4-fluoropyridine (100 mg, 1.0 eq) with indole (1.0 eq) is the same as that in Example 1.

[0086] Compound I6: 68 mg of pale yellow solid, yield 46%, HPLC purity = 99.11%. Figure 6 This is the 1H NMR spectrum of Compound I6. 11H NMR (400 MHz, DMSO-d6) δ 8.60 (dd, J = 9.2, 5.7 Hz, 1H), 8.53 (d, J = 8.3 Hz, 1H), 8.08 (d, J = 3.6 Hz, 1H), 7.77 (dd, J = 11.3, 2.1 Hz, 1H), 7.65 (d, J = 7.7 Hz, 1H), 7.32 - 7.16 (m, 3H), 6.79 (d, J = 3.5 Hz, 1H).

[0087] Example 7

[0088]

[0089] The method for preparing I7 by reacting 3-bromo-6-fluoroisoquinoline (100 mg, 1.0 eq) with indole (1.0 eq) is the same as that in Example 1.

[0090] Compound I7: 30 mg of white solid, yield 20%, HPLC purity = 98.42%. Figure 7 This is the 1H nuclear magnetic resonance spectrum of compound I7. 1 1H NMR (400 MHz, CDCl3) δ 9.22 (s, 1H), 8.17 (d, J = 8.3 Hz, 1H), 8.07 - 7.98 (m, 1H), 7.84 (d, J = 3.5 Hz, 1H), 7.75 (s, 1H), 7.69 (d, J = 7.8 Hz, 1H), 7.47 (dd, J = 9.5, 2.2 Hz, 1H), 7.33 (ddd, J = 11.1, 6.3, 2.4 Hz, 2H), 7.24 - 7.19 (m, 1H), 6.76 (d, J = 3.4 Hz, 1H).

[0091] Example 8

[0092]

[0093] The method for preparing I8 by reacting 1-bromoisoquinoline (100 mg, 1.0 eq) with 6-fluoroindole (1.0 eq) is the same as that in Example 1.

[0094] Compound I8: 50 mg of yellow oil, yield 35%, HPLC purity = 96.84%. Figure 8 This is the 1H nuclear magnetic resonance spectrum of compound I8. 1HNMR(400MHz,CDCl3)δ9.37(s,1H),8.63(s,1H),8.15(dd,J=6.4,2.9Hz,1H),7.69(ddt,J=18.0,8.7,5.3Hz,3H),7.53-7.45(m,1H),7.33(d,J=3.2Hz,1H),7.02-6.91(m,1H),6.78(d,J=3.2Hz,1H),6.70(dd,J=9.7,2.1Hz,1H).

[0095] Example 9

[0096]

[0097] The method for preparing I9 by reacting 7-bromoisoquinoline (100 mg, 1.0 eq) with 6-fluoroindole (1.0 eq) is the same as that in Example 1.

[0098] Compound I9: 37 mg of yellow solid, yield 25%, HPLC purity = 96.78%. Figure 9 This is the 1H NMR spectrum of compound I9. 1 H NMR(400MHz,DMSO-d6)δ9.43(s,1H),8.55(d,J=5.7Hz,1H),8.33(d,J=1.8Hz,1H),8.15(d,J=8.8Hz,1H),8.01(dd,J=8.8,2.2Hz,1H),7.89(d,J=5.7Hz,1H),7.80(d,J=3.3Hz,1H),7.69(dd,J=8.6,5.6Hz,1H),7.51(dd,J=10.4,1.9Hz,1H),7.04(td,J=9.4,2.2Hz,1H),6.79(d,J=3.2Hz,1H).

[0099] Example 10

[0100]

[0101] The method for preparing I10 by reacting 5-bromoisoquinoline (100 mg, 1.0 eq) with 6-fluoroindole (1.0 eq) is the same as that in Example 1.

[0102] Compound I10: 43 mg of light yellow solid, yield 28%, HPLC purity = 97.99%. Figure 10 This is the 1H NMR spectrum of compound I10. 11H NMR (400 MHz, DMSO-d6) δ 9.51 (s, 1H), 8.49 (d, J = 5.9 Hz, 1H), 8.33 (d, J = 8.1 Hz, 1H), 7.95 (d, J = 7.1 Hz, 1H), 7.87 (t, J = 7.8 Hz, 1H), 7.73 (dd, J = 8.6, 5.5 Hz, 1H), 7.66 (d, J = 3.2 Hz, 1H), 7.15 (d, J = 5.9 Hz, 1H), 7.01 (td, J = 9.5, 2.2 Hz, 1H), 6.83 (d, J = 3.2 Hz, 1H), 6.74 (dd, J = 10.0, 1.9 Hz, 1H).

[0103] Test Example 1

[0104] Determination of the Affinity of Compounds I1 - I10 for Tau Protein Aggregates

[0105] K18 - Tau has a complete microtubule - binding domain. In this section, K18 - Tau was used for competitive binding assays. The mixture of Aβ 1-42 aggregates or K18 - Tau aggregates and the test compound was placed in a black 96 - well plate and gently shaken at 37 °C for 30 minutes. The fluorescence intensity of each well was obtained using an Infinite M200pro microplate reader. The excitation / emission wavelengths of Aβ 1-42 aggregates are 540 / 632 nm respectively, and the excitation / emission wavelengths of K18 - Tau aggregates are 524 / 654 nm respectively. The fluorescence signals of all test compounds were also measured in the same way to reduce the background in detection. All data were input into GraphPad Prism 8.0 software, and the inhibitor constant (K i ) value was calculated according to the Cheng - Prusoff equation.

[0106] K i = IC 50 / (1 + [L] / K d )

[0107] where [L] is the concentration; K d is the equilibrium dissociation constant of the control radioligand; IC 50 is the half - maximal inhibitory concentration. K d is calculated by "Scatchard homologous displacement analysis", which is calculated by multiple self - displacement runs of the AD brain.

[0108] The K 1-42 values of Compounds I1 - I10 for Tau(K18Δ280) and Abeta i are shown in Table 2.

[0109] Table 2 Affinity of Compounds I1 - I10 for Tau Protein Aggregates

[0110]

[0111] "-" indicates not detected. The results were measured by three independent experiments and the values are averages.

[0112] As can be seen from Table 2, the pyridine derivatives provided by the present invention have strong affinity and selectivity for Tau protein aggregates. Among them, the affinity of Compound I10 for Tau protein aggregates is 11.29 nM, the affinity for Aβ is 86.69 nM, and the selectivity is 7.68, with the highest selectivity for Tau protein aggregates. The affinities of Compounds I1, I2, I4, and I8 for Tau protein aggregates are all < 20 nM, showing significant affinity for Tau protein aggregates.

[0113] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A pyridine derivative, characterized in that: It has the structure shown in Formula I: Wherein, X is carbon, hydrogen or nitrogen, Y is carbon, hydrogen or nitrogen, and R1 is halogen or hydrogen; R2 is R3 is halogen or hydrogen.

2. The pyridine derivative according to claim 1, characterized in that: The pyridine derivative has any one of the structures shown in I1 to I10:

3. The method for preparing the pyridine derivatives according to claim 1 or 2, characterized in that: The following steps are involved: Mixing compound a, compound b, an alkaline reagent, a coupling catalyst and an organic solvent to carry out a coupling reaction to obtain the pyridine derivative; The structural formula of the compound b is as follows: The structural formula of the compound a is as follows:

4. The preparation method according to claim 3, characterized in that: The molar ratio of compound a to compound b is 1:0.5-1.5; The alkaline reagent includes one or more of alkali metal alcoholates, alkali metal hydrides, organic alkali metal compounds and alkali metal hydroxides; the molar ratio of the compound a to the alkaline reagent is 1:0.5-5; The coupling catalyst includes methanesulfonic acid (2-di-tert-butylphosphino-2',4',6'-triisopropyl-1,1'-biphenyl) (2'-amino-1,1'-biphenyl-2-yl) palladium (II) (tBuXPhos-Pd-G3), chloro [2-(di-tert-butylphosphino)-2',4',6'-triisopropyl-1,1'-biphenyl] [2-(2-aminoethyl)phenyl)] palladium (II), methanesulfonic acid (2-di-tert-butylphosphino-2',4',6'-triisopropylbiphenyl) (2'-methylamino-1,1'-biphenyl-2-yl) palladium (II), One or more of methanesulfonate [n-butyldi(1-adamantyl)phosphine](2'-methylamino-1,1'-biphenyl-2-yl)palladium(II), methanesulfonate (2-dicyclohexylphosphino-2',4',6'-tri-isopropyl-1,1'-biphenyl)(2'-amino-1,1'-biphenyl-2-yl)palladium(II) and methanesulfonate (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)(2-amino-1,1'-biphenyl-2-yl)palladium(II); the molar ratio of the compound a to the coupling catalyst is 1:0.01-0.

1.

5. The preparation method according to claim 3, characterized in that: The organic solvent includes one or more of tetrahydrofuran, N,N-dimethylformamide, 1,4-dioxane, acetonitrile and dimethyl sulfoxide.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The coupling reaction is carried out at a temperature of 60 to 80° C. and for a time of 12 to 24 hours; the coupling reaction is carried out under a protective atmosphere.

7. Use of the pyridine derivatives according to claim 1 or 2 as protein aggregate ligands.

8. The use according to claim 7, characterized in that: The protein aggregates include Tau protein aggregates.

9. A diagnostic drug comprising the pyridine derivative according to claim 1 or 2, wherein the pyridine derivative contains a radioactive halogen.

10. Use of the pyridine derivatives according to claim 1 or 2 or the diagnostic drug according to claim 9 in the preparation of drugs for diagnosing neurodegenerative diseases.

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