A protac compound, preparation method and application thereof as a targeted ab aggregate degrading agent

Abstract

The application discloses a PROTAC compound, a preparation method and application as a targeted A beta aggregate degradation agent, and belongs to the technical field of biological medicines. The application provides a small molecule QR which is combined with various aggregation forms of A beta, and the small molecule QR is used as a ligand for targeting A beta and aggregates. A type of PROTAC compound is designed and synthesized by using a carefully designed and efficient chemical synthesis method. D4 in the PROTAC compound has high affinity to various aggregation forms of A beta, and can promote effective degradation of various aggregation forms of A beta through different ways. The oligomer mainly plays a high-efficiency degradation role through UPS, and the polymer plays a degradation role through promoting the autophagy-lysosome system. In addition, intracerebral / subcutaneous administration shows that the A beta level in the brain can be significantly reduced, the expression of synaptic related proteins can be restored, the inflammatory environment in the brain can be reduced, and the cognitive function of AD model mice can be improved. The application has great significance in the field of AD and other disease treatments.

Description

Technical Field

[0001] This invention belongs to the field of biomedical technology, specifically relating to a PROTAC compound, its preparation method, and its application as a targeted Aβ aggregate degrader. Background Technology

[0002] β-amyloid (Aβ) deposition in the brain is a key pathological feature of Alzheimer's disease (AD). Aβ is hydrophobic and readily aggregates, with Aβ oligomers and fibrils being the main Aβ types found in the naturally soluble protein fraction of the AD brain. These Aβ aggregates drive AD pathological progression through pathways promoting tau pathology, neuroinflammation, and impaired neuronal and synaptic function. Studies show that clinical drugs targeting Aβ monomer production and aggregation often face challenges due to high toxicity or unsatisfactory therapeutic effects. However, reducing Aβ aggregate levels in the brain can slow cognitive decline, highlighting Aβ aggregates as a key target for AD treatment. Therefore, the development of drugs targeting brain Aβ aggregates is crucial for AD treatment. It is well known that small molecules constitute the vast majority of central nervous system (CNS) drugs because they can easily cross the blood-brain barrier via passive or carrier-mediated transport. More importantly, small molecule drugs are more patient-friendly and have higher compliance due to their lower cost, diverse administration methods, and storage stability. Therefore, the development of small molecule drugs targeting Aβ aggregates holds significant promise.

[0003] However, a technical challenge lies in the fact that traditional small-molecule drugs bind to enzymes or receptors through specific "pockets," thereby acting as "switches" to regulate biological activities. But misfolded proteins lack classic active "pockets," making it difficult to target Aβ aggregates with traditional small-molecule compounds. This may explain the poor efficacy of clinical drug treatments targeting Aβ aggregates. The turning point is the development of protein-targeting chimeras (PROTACs), which effectively address the problem of untargetable proteins. Therefore, PROTACs have been widely studied in neurodegenerative diseases related to misfolded proteins, such as tau protein in Alzheimer's disease (AD), α-synuclein in Parkinson's disease (PD), and mutant huntingtin protein in HD. Specifically, PROTACs act as "molecular bridges," with one end containing a ligand that binds to the target protein and the other end containing a ligand that binds to E3 ubiquitin ligase. By promoting ubiquitination of the target protein, they induce its degradation. However, PROTACs are far more effective at degrading soluble aggregates with low aggregation levels than those with high aggregation levels. Therefore, although Aβ plaques showed ubiquitin positivity in clinical autopsy brain slices, they were not effectively removed. This may be attributed to the fact that Aβ aggregates need to be unfolded and linearized before they can pass through the narrow pores of the 20S core particles in the UPS for degradation, while highly aggregated Aβ aggregates, due to their rigid structure, cannot be well linearized and are therefore difficult to degrade through the UPS. Therefore, there are currently no PROTACs for the degradation of Aβ and its aggregates.

[0004] Recent studies have shown that aspirin mediates the degradation of α-syn fibrils (PFFs) via the lysosomal pathway by increasing K63-linked ubiquitination. This suggests that lysosomal degradation mediated by increasing K63-linked ubiquitination via PROTAC may be a promising approach to clearing highly aggregated Aβ aggregates. However, detailed research in this area is still limited. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a small molecule QR that binds to multiple Aβ aggregation forms. Using this QR as a ligand targeting Aβ and its aggregates, a class of PROTAC compounds was designed and synthesized using a carefully designed and efficient chemical synthesis method. The D4 molecule in this compound exhibits high affinity for various Aβ aggregation forms and can promote the effective degradation of Aβ through different pathways. Oligomers primarily exert their efficient degradation effect through UPS (Up-Solution-Under-Plasma), while polymers exert their degradation effect by promoting the autophagy-lysosomal system. Furthermore, intracerebral / subcutaneous administration showed that it significantly reduced intracerebral Aβ levels, while simultaneously restoring synaptic-related protein expression and reducing the intracerebral inflammatory environment, collectively improving cognitive function in AD model mice. This invention provides new insights for developing PROTAC molecules targeting Aβ aggregates.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: One objective of this invention is to provide a PROTAC compound with the structure shown in formula (I): (I); Wherein A is selected from one of the following formulas (II) to (V): (II) (III) (IV) (V).

[0007] Furthermore, the structure of A in the PROTAC compound is shown in the following formula (II): (II).

[0008] Furthermore, the structure of A in the PROTAC compound is shown in the following formula (III): (III).

[0009] Furthermore, the structure of A in the PROTAC compound is shown in the following formula (IV): (IV).

[0010] Furthermore, the structure of A in the PROTAC compound is shown in the following formula (V): (V).

[0011] A second objective of this invention is to provide a method for preparing the PROTAC compound when structure A is as shown in formula (II), comprising the following steps: (1) React 4-acetaminobenzaldehyde with an aqueous sodium hydroxide solution in methanol to obtain 4-hydroxybenzaldehyde (A2); (2) The 4-hydroxybenzaldehyde (A2) obtained in step (1) is reacted with di-tert-butyl dicarbonate in anhydrous tetrahydrofuran in the presence of N,N-diisopropylethylamine to obtain 4-(tert-butyloxycarbonyloxy)benzaldehyde (A3). (3) The 4-(tert-butoxycarbonyloxy)benzaldehyde (A3) obtained in step (2) is reacted with iodomethane in anhydrous N,N-dimethylformamide in the presence of sodium hydride to obtain 4-(tert-butoxycarbonyloxy)-3-methoxybenzaldehyde (A4). (4) React the 4-(tert-butoxycarbonyloxy)-3-methoxybenzaldehyde (A4) obtained in step (3) with trifluoroacetic acid in dichloromethane to remove the protecting group and obtain 3-methoxy-4-hydroxybenzaldehyde (A5). (5) The 3-methoxy-4-hydroxybenzaldehyde (A5) obtained in step (4) is reacted with 2-bromoacetyl bromide in anhydrous dichloromethane in the presence of triethylamine to give 2-bromo-1-(3-methoxy-4-hydroxyphenyl) ethyl ketone (A6). (6) The 2-bromo-1-(3-methoxy-4-hydroxyphenyl) ethyl ketone (A6) obtained in step (5) is reacted with VHL ligand 1 in anhydrous acetonitrile in the presence of potassium carbonate and a catalytic amount of potassium iodide to obtain intermediate A7. (7) React the intermediate A7 obtained in step (6) with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

[0012] A third objective of this invention is to provide a method for preparing the PROTAC compound when structure A is as shown in formula (III), comprising the following steps: (1) Compound B4 is reacted with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to give activated ester C1; (2) The activated ester C1 obtained in step (1) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate C2; (3) The intermediate C2 obtained in step (2) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinolineonium salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile upon heating, and the structure of compound B4 is shown in formula (VI): (VI).

[0013] The fourth objective of this invention is to provide a method for preparing the PROTAC compound when structure A is as shown in formula (IV), comprising the following steps: (1) React activated ester C1 with ethanolamine in dichloromethane in the presence of triethylamine to obtain intermediate D1; (2) The intermediate D1 obtained in step (1) is reacted with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to obtain activated ester D2; (3) The activated ester D2 obtained in step (2) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate D3; (4) The intermediate D3 obtained in step (3) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

[0014] The fifth objective of this invention is to provide a method for preparing the PROTAC compound when structure A is as shown in formula (V), comprising the following steps: (1) React activated ester D2 with ethanolamine in dichloromethane in the presence of triethylamine to obtain intermediate F1; (2) React the intermediate F1 obtained in step (1) with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to obtain intermediate F2; (3) The intermediate F2 obtained in step (2) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate F3; (4) The intermediate F3 obtained in step (3) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

[0015] The sixth objective of this invention is to provide the use of any of the above-described PROTAC compounds in the preparation of a degrading agent targeting Aβ aggregates, wherein the degrading agent targeting Aβ aggregates comprises any of the described PROTAC compounds and a pharmaceutically acceptable carrier.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a small molecule QR that binds to multiple aggregation forms of Aβ. Using this QR as a ligand targeting Aβ and its aggregates, a class of PROTAC compounds was designed and synthesized using a carefully designed and efficient chemical synthesis method. The D4 molecule in this class exhibits high affinity for various aggregation forms of Aβ and can promote the effective degradation of Aβ through different pathways. Oligomers primarily exert their efficient degradation effect through UPS (Up-Solution-Under-Plasma), while polymers exert their degradation effect by promoting the autophagy-lysosomal system. Furthermore, intracerebral / subcutaneous administration showed that it significantly reduced intracerebral Aβ levels, while simultaneously restoring synaptic-related protein expression and reducing the intracerebral inflammatory environment, collectively improving cognitive function in AD model mice. This invention provides new insights into the development of PROTAC molecules targeting aggregates. Attached Figure Description

[0017] Figures 1-6 This is an NMR data image of probe I (A9) in Embodiment 1 of the present invention.

[0018] Figures 7-15 The images show the NMR data and high-performance liquid chromatography (HPLC) chromatogram of probe III (C3) in Example 1 of this invention.

[0019] Figures 16-20 The images show the NMR data and high-performance liquid chromatography (HPLC) chromatogram of probe IV (D4) in Example 1 of this invention.

[0020] Figures 21-25 The images show the NMR data and high-performance liquid chromatography (HPLC) chromatogram of probe VI (F4) in Example 1 of this invention.

[0021] Figure 26 The chemical structure diagrams of the four probes in Example 1 of this invention are shown.

[0022] Figure 27 This presents the preliminary screening results of the affinity between Aβ PROTACs and Aβ aggregates and the degradation effect of targeting Aβ PROTAC molecules in Example 2 of the present invention.

[0023] Figure 28 This demonstrates the dose-response relationship of compound D4 in degrading Aβ in Example 2 of the present invention.

[0024] Figure 29 This demonstrates the time-dependent relationship between the degradation of Aβ by compound D4 in Example 2 of this invention.

[0025] Figure 30 This demonstrates the degradation mechanism of Aβ by compound D4 in Example 2 of the present invention.

[0026] Figure 31 This demonstrates that compound D4 in Example 2 of the present invention can degrade Aβ protein in the brain of 5×FAD.

[0027] Figure 32 This demonstrates that compound D4 in Example 2 of the present invention can treat and alleviate AD-related pathology. Detailed Implementation

[0028] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and essence of the invention are within the scope of the invention. The reagents, products, and instruments used in the following examples are all commercially available, and the methods used in the examples, unless otherwise specified, are consistent with conventionally used methods.

[0029] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0030] Example 1 This embodiment provides a class of PROTAC compounds targeting Aβ, including probe I (A9), probe III (C3), probe IV (D4), and probe VI (F4), and the specific preparation steps are as follows: 1. Synthesis of Probe I (A9) The synthetic route for probe I (A9) is as follows: The specific synthesis method of probe I (A9) is as follows: (1) Weigh 4-acetaminobenzaldehyde (A1, 2 g, 12.3 mmol, 1.0 equivalent) and dissolve it in 20 mL of methanol solution. Then, dissolve sodium hydroxide (2 g, 49 mmol, 4.0 equivalent) in an appropriate amount of water to prepare a solution and add it dropwise to the reaction system. Heat the resulting solution under reflux and stir for 2 hours. After the reaction solution cools to room temperature, dilute it with dichloromethane and wash it with saturated sodium chloride solution. Combine the organic layers, dry them, and concentrate the filtrate. Dissolve the residue in a small amount of cyclohexane and recrystallize it from dichloromethane to give the yellow product A2 (1.4 g, 11.6 mmol, yield 94%). 1 H NMR (400 MHz, CDCl3) δ9.74 (s, 1H), 7.68 (d, J = 8.6 Hz, 2H), 6.69 (d, J = 8.5 Hz, 2H), 4.30 (s, 2H). 13 C NMR (100 MHz, CDCl3) δ 190.57, 152.63, 132.46, 127.59, 114.16. (2) Compound A2 (590 mg, 4.9 mmol, 1.0 equivalent) and di-tert-butyl dicarbonate (1.2 g, 5.4 mmol, 1.1 equivalent) were weighed and dissolved in 12 mL of anhydrous tetrahydrofuran. N,N-diisopropylethylamine (1.26 g, 9.8 mmol, 2.0 equivalent) was then added to the reaction system. Under nitrogen protection, the solution was heated under reflux and stirred for 12 hours. After cooling to room temperature, the solvent was removed by concentration. The residue was partitioned and washed with dichloromethane, and the combined organic phases were concentrated to give a pale yellow solid A3 (0.6 g, 2.7 mmol, yield 55%). 1 H NMR (400 MHz, CDCl3) δ 10.14 (s, 1H), 8.07(d,J = 8.6 Hz, 2H), 7.80 (d, J = 8.6 Hz, 2H), 1.77 (s, 9H). 13 C NMR (100 MHz, CDCl3) δ 190.21, 151.27, 143.51, 130.36, 116.93, 80.51, 27.33. (3) Weigh compound A3 (600 mg, 2.7 mmol, 1.0 equivalent) and sodium hydride (130 mg, 3.2 mmol, 1.2 equivalent), and dissolve them in 12 mL of anhydrous N,N-dimethylformamide. Place the mixture in an ice bath and stir for 30 minutes under nitrogen protection. Then add iodomethane (460 mg, 3.2 mmol, 1.2 equivalent) to the reaction system and continue stirring overnight at room temperature. After the reaction is complete, remove the solvent by rotary evaporation. The residue obtained is separated and concentrated by silica gel column chromatography using petroleum ether / ethyl acetate (50:1 v / v) as the elution system to obtain an oily liquid product A4 (398 mg, 1.7 mmol, yield 63%).

[0031] 1 H NMR (400 MHz, CDCl3) δ 9.91 (s, 1H), 7.80 (d, J = 8.6 Hz, 2H), 7.42(d, J = 8.6 Hz, 2H), 3.29 (s, 3H), 1.45 (s, 9H). 13 C NMR (100 MHz, CDCl3) δ191.10, 153.92, 149.22, 132.65, 130.08, 124.60, 81.31, 36.76, 28.22. (4) Weigh out compound A4 (398 mg, 1.7 mmol) and dissolve it in 6 mL of anhydrous dichloromethane. Cool the reaction system to 0 °C and then add trifluoroacetic acid (3 mL). Stir the mixture at room temperature for 6 hours, and then remove the solvent by rotary evaporation to obtain the oily liquid product A5. 1 H NMR (400 MHz, CDCl3) δ 9.68 (s, 1H), 7.72 (d, J = 8.4 Hz, 2H), 6.63 (d, J = 8.4 Hz, 2H), 2.93 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 190.46, 154.32, 132.45, 126.64, 111.63, 30.20. (5) Weigh compound A5 (30 mg, 0.22 mmol, 1.0 equivalent) and triethylamine (68 mg, 0.67 mmol, 3.0 equivalent) and dissolve them in 3 mL of anhydrous dichloromethane. After cooling the reaction system to 0 °C, slowly add 2-bromoacetyl bromide (90 mg, 0.45 mmol, 2.0 equivalent) dropwise. Stir the mixture at room temperature for 1 hour and monitor the reaction until complete by thin-layer chromatography (TLC). Then remove the solvent by rotary evaporation. The residue was separated and concentrated by silica gel column chromatography using petroleum ether / ethyl acetate (volume ratio 10:1) as the elution system to give a light brown solid product A6 (28 mg, 0.11 mmol, yield 50%). 1 H NMR (400 MHz, CDCl3) δ 10.06 (s, 1H), 7.99 (d, J = 8.3 Hz, 2H), 7.49 (d, J = 8.3 Hz, 2H), 3.71 (s, 2H), 3.37 (s, 3H). HRMS (ESI / Q-TOF) m / z of [M+Na] + :Calcd for C 10 H 10 BrNNaO2 277.9787; Found 277.9794. (6) Weigh VHL ligand 1 (30 mg, 0.06 mmol, 1.0 equivalent), compound A6 (28 mg, 0.11 mmol, 2.0 equivalent), potassium carbonate (18 mg, 0.12 mmol, 2.0 equivalent), and trace potassium iodide (5 mg), and dissolve them in 5 mL of anhydrous acetonitrile. Heat the mixture under reflux and stir for 12 hours. After the reaction is complete, remove the solvent by rotary evaporation. Separate the residue by silica gel column chromatography to obtain a light brown solid product A7 (11.3 mg, 0.02 mmol, yield 33%). 1 H NMR (400 MHz, CDCl3) δ10.03 (s, 1H), 8.68 (s, 1H), 7.94 (d, J = 8.4 Hz, 2H), 7.42 (d, J = 8.3 Hz, 2H), 7.36 (q, J = 8.3 Hz, 4H), 4.82 (d, J= 8.8 Hz, 1H), 4.63 (dd, J = 14.8,7.0 Hz, 1H), 4.50-4.44 (m, 1H), 4.33-4.28 (m, 1H), 3.88-3.79 (m, 1H), 3.70-3.68 (m, 2H), 3.29 (s, 3H), 3.20-3.14 (m, 2H), 2.52 (s, 3H), 2.46-2.34 (m,2H), 2.16-2.12 (m, 1H), 0.86 (s, 9H). HRMS (ESI / Q-TOF) m / z of [M+Na] + : Calcdfor C 32 H 39 N5NaO5S 628.2564; Found 628.2572. (7) In a dry reaction flask, 2-methylquinoline (5 g, 34.9 mmol) was dissolved in acetonitrile (50 mL), followed by the addition of iodoethane (16.3 g, 104.8 mmol). The mixture was heated in an oil bath at 80 °C for 16 hours. After the reaction system cooled to room temperature, the solvent was removed by vacuum distillation. The crude product was purified by recrystallization from anhydrous ethanol to obtain a yellowish-brown solid product A8 (2.6 g, yield 25%). 1 H NMR (400 MHz, DMSO- d 6) δ 9.10 (d, J = 8.0 Hz, 1H), 8.61 (d, J =8.0 Hz, 1H), 8.42 (d, J = 8.0 Hz, 1H), 8.25 (t, J = 4.0 Hz, 1H), 8.22 (d, J =4.0 Hz, 1H), 8.00 (t, J = 4.0 Hz, 1H), 5.00 (dd, J = 12.0, 8.0 Hz, 2H), 3.11(s, 3H), 1.53 (t, J = 8.0 Hz, 3H). HRMS (ESI / Q-TOF): m / z: [M+Na] + Calcd.C 12 H 14 N + For 172.1121, Found 172.1120. (8) Weigh compound A7 (11.3 mg, 0.02 mmol, 1.0 equivalent) and compound A8 (3.2 mg, 0.02 mmol, 1.0 equivalent) and place them in a dry reaction vessel under nitrogen protection. Add 2 mL of anhydrous methanol solution to the system, mix thoroughly, and then add a small amount of piperidine. Heat the mixture under reflux and stir for 1 hour. Monitor the reaction by thin-layer chromatography (TLC) until complete, and then remove the solvent under reduced pressure. Recrystallize the residue from methanol to obtain a light brown solid A9 (probe I, 9 mg, 0.012 mmol, yield 59%). 1 H NMR (400 MHz, DMSO- d 6) δ 9.11 (d, J = 9.0 Hz, 1H), 8.98 (d, J = 2.2 Hz, 1H), 8.71-8.57 (m, 3H), 8.43-8.39 (m, 2H), 8.33-8.17 (m, 4H), 8.06(d, J = 8.5 Hz, 1H), 8.01 -7.96 (m, 1H), 7.54 (d, J = 8.4 Hz, 2H), 7.44-7.37(m, 2H), 5.48-5.45 (m, 2H), 5.22-5.17 (m, 2H), 4.77-4.74 (m, 1H), 4.45-4.38(m, 3H), 3.98-3.92 (m, 2H), 3.26 (s, 3H), 3.10 (s, 1H), 2.44 (s, 3H), 1.65-1.61 (m, 3H), 1.58-1.53 ​​(m, 4H), 1.33 (s, 2H), 1.25-1.23 (m, 3H), 1.05-0.72(m, 9H). HRMS (ESI / Q-TOF) m / z of [M+H] + Calculated for C 44 H 51 N6O4S 759.3687; Found759.3685. The NMR data of probe I (A9) are shown in the figure. Figures 1-6 As shown.

[0032] 2. Synthesis of Probe III (C3) The synthetic route for probe III (C3) is as follows: The synthesis method of probe III (C3) is as follows: (1) Compound B4 (50.0 mg, 1.0 equivalent) and triethylamine (0.12 mL, 3.0 equivalent) were dissolved in dichloromethane, and 4-nitrobenzene chloroformate (67.3 mg, 1.2 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 12 hours, the crude product was purified by column chromatography using petroleum ether / ethyl acetate (v / v) as the eluent to give a yellow oily product C1 (79.2 mg, yield 82%). 1 H NMR (400 MHz, CDCl3) δ 9.75 (s, 1H), 8.23 ​​(d, J = 9.1 Hz, 2H), 7.75 (d, J = 8.9 Hz, 2H), 7.23 (d, J = 9.1 Hz, 2H), 6.79 (d, J = 8.9 Hz, 2H), 4.49 (t, J = 5.8 Hz, 2H), 3.83 (t, J = 5.8 Hz, 2H), 3.13 (s, 3H). 13 C NMR(100 MHz, CDCl3) δ 190.66, 155.36, 153.42, 152.61, 145.67, 132.39, 126.29,125.46, 121.86, 115.83, 111.38, 66.01, 50.62, 39.05. (2) VHL ligand 1 (30 mg, 1.0 equivalent) and compound C1 (44.2 mg, 2.0 equivalent) were dissolved in DMF, and N-methylmorpholine (NMM, 42.4 μL, 6.0 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 12 hours, the crude product was purified by column chromatography using dichloromethane / methanol (25:1 v / v) as the eluent to obtain product C2 (34.1 mg, yield 84%). 1 H NMR (400 MHz, CDCl3) δ 9.68 (s, 1H), 8.67 (s, 1H), 7.70 (d, J = 8.7Hz, 2H), 7.34 (t, J = 6.2 Hz, 4H), 6.70 (d, J = 8.6 Hz, 2H), 5.41 (d, J= 9.1Hz, 1H), 4.68 (t, J = 7.8 Hz, 1H), 4.58- 4.49 (m, 2H), 4.32 (dd, J = 15.0,5.3 Hz, 1H), 4.25-4.17 (m, 3H), 3.90 (d, J = 11.2 Hz, 1H), 3.81 (t, J = 4.9Hz, 1H), 3.68 (t, J = 5.9 Hz, 1H), 3.65-3.57 (m, 2H), 3.04 (s, 3H), 2.50 (s,3H), 2.16-2.08 (m, 1H), 0.87 (s, 9H). 13 C NMR (100 MHz, CDCl3) δ 190.65,171.67, 170.87, 156.46, 153.72, 150.49, 148.57, 138.17, 132.33, 131.73,131.07, 129.63, 128.19, 125.66, 111.21, 62.12, 59.40, 58.73, 56.84, 51.02,43.36, 38.74, 36.28, 35.49, 29.81, 26.34, 16.15. HRMS (ESI / Q-TOF) m / z of [M+Na] + Calcd for C 34 H 41 N5NaO6S 658.2670; Found 672.2666. (3) Compound C2 (32.0 mg, 1.0 equivalent) and A8 (7.8 mg, 1.0 equivalent) were dissolved in 1.0 mL of anhydrous methanol, a small amount of piperidine was added, and the mixture was heated under reflux for 2 hours. After the reaction was completed, all solvents were evaporated, and the crude product was washed with diethyl ether to obtain a purple powder product C3 (probe III, 36.0 mg, yield 91%). 1 H NMR (400 MHz, DMSO- d 6) δ 8.97(s, 1H), 8.79 (s, 1H), 8.56 (d, J = 19.6 Hz, 2H), 8.43 (d, J = 9.3 Hz, 1H), 8.28 (dd, J= 24.9, 11.5 Hz, 2H), 8.09 (s, 1H), 7.92-7.81 (m, 2H), 7.48-7.35(m, 4H), 7.32-6.97 (m, 2H), 6.86 (s, 2H), 5.03 (s, 2H), 4.41 (d, J = 28.1 Hz,3H), 4.25-4.19 (m, 2H), 3.71-3.62 (m, 3H), 3.38 (q, J = 6.3 Hz, 1H), 3.16 (s,3H), 2.42 (s, 3H), 2.12-1.98 (m, 1H), 1.96-1.82 (m, 1H), 1.53 (t, J = 16.8Hz, 3H), 0.92 (s, 9H). HRMS (ESI / Q-TOF) m / z of [M+H] + Calcd for C 45 H 53 N6O5S + 789.3793; Found 789.3793. The NMR data of probe III (C3) are shown in the figure. Figures 7-14 As shown, the high-performance liquid chromatography (HPLC) chromatogram is as follows: Figure 15 As shown.

[0033] 3. Chemical synthesis of probe IV (D4) The synthetic route for probe IV (D4) is as follows: The synthesis method of probe IV (D4) is as follows: (1) Compound C1 (30.0 mg, 1.0 equivalent) and triethylamine (36.3 µL, 3.0 equivalent) were dissolved in dichloromethane, and ethanolamine (10.6 mg, 3.0 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 24 hours, the solution was purified by column chromatography using dichloromethane / methanol (volume ratio 40:1) as the eluent to obtain a yellow oily product D1 (20.4 mg, yield 88%). 1 H NMR (400 MHz, CDCl3) δ 9.73 (s, 1H), 7.73 (d, J = 8.9 Hz, 2H), 6.76(d, J = 8.6 Hz, 2H), 5.06 (s, 1H), 4.28 (t, J= 5.9 Hz, 2H), 3.72-3.63 (m,4H), 3.31 (t, J = 5.5 Hz, 2H), 3.09 (s, 3H). (2) Compound D1 (20.4 mg, 1.0 equivalent) and triethylamine (31.9 µL, 3.0 equivalent) were dissolved in dichloromethane, and 4-nitrobenzene chloroformate (18.5 mg, 1.2 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 12 hours, the crude product was purified by column chromatography using petroleum ether / ethyl acetate (volume ratio 1:1) as the eluent to obtain a yellow oily product D2 (24.4 mg, yield 74%). 1 H NMR (400 MHz, CDCl3) δ 9.73 (s, 1H), 8.28 (d, J = 9.1 Hz, 2H), 7.73 (d, J = 8.9 Hz, 2H), 7.38 (d, J = 9.2 Hz, 2H), 6.76 (d, J = 8.5 Hz,2H), 5.02 (s, 1H), 4.30 (t, J = 5.4 Hz, 4H), 3.70 (t, J = 5.9 Hz, 2H), 3.53(q, J = 5.6 Hz, 2H), 3.09 (s, 3H). 13 C NMR (100 MHz, CDCl3) δ 190.46, 153.74,152.56, 132.26, 125.88, 125.57, 121.95, 111.34, 68.29, 62.13, 51.20, 40.07,38.88. HRMS (ESI / Q-TOF) m / z of [M+Na] + Calcd for C 36 H 46 N6NaO8S 745.2990; Found745.2992. (3) VHL ligand 1 (17.4 mg, 1.0 equivalent) and compound D2 (32.1 mg, 2.0 equivalent) were dissolved in 0.4 mL DMF, and N-methylmorpholine (NMM, 24.6 μL, 6.0 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 12 hours, the crude product was purified by column chromatography using dichloromethane / methanol (25:1 v / v) as the eluent to obtain product D3 (22.8 mg, yield 85%). 1 H NMR (400 MHz, CDCl3) δ 9.67 (s, 1H), 8.67 (s, 1H), 7.69 (d, J =8.9 Hz, 2H), 7.34 (t, J = 5.7 Hz, 4H), 6.74 (d, J = 8.5 Hz, 2H), 5.57 (d, J =9.3 Hz, 1H), 5.15 (s, 1H), 4.72 (t, J = 7.9 Hz, 1H), 4.55 (d, J = 16.4 Hz, 2H), 4.32 (dd, J = 14.8, 5.3 Hz, 2H), 4.26-4.19 (m, 2H), 4.02-3.92 (m, 2H), 3.88 (d, J = 4.8 Hz, 1H), 3.64 (d, J = 12.3 Hz, 3H), 3.44-3.31 (m, 1H), 3.31-3.18 (m, 1H), 3.05 (s, 3H), 2.72 (s, 1H), 2.50 (s, 3H), 2.18-2.11 (m, 1H), 0.92 (s, 9H). 13C NMR (100 MHz, CDCl3) δ 190.66, 171.89, 171.07, 153.83,150.47, 148.54, 138.26, 132.23, 131.70, 131.00, 129.57, 128.14, HRMS (ESI / Q-TOF) m / z of [M+Na] + : Calcd forC 36 H 46 N6NaO8S 745.2990; Found 745.2992. (4) Compound D3 (20.0 mg, 1.0 equivalent) and A8 (4.8 mg, 1.0 equivalent) were dissolved in 1.0 mL of anhydrous methanol, a small amount of piperidine was added, and the mixture was heated under reflux for 2 hours. After the reaction was completed, all solvents were evaporated, and the crude product was washed with diethyl ether to obtain a purple powder product D4 (22.0 mg, yield 91%). 1 H NMR (400 MHz, DMSO- d 6) δ 8.97 (s, 1H), 8.81 (d, J = 9.1 Hz, 1H), 8.57 (s, 1H), 8.43 (d, J = 8.8 Hz, 1H), 8.28 (dd, J = 24.2, 11.3 Hz, 2H), 8.09 (t, J = 8.0 Hz, 1H), 7.93-7.81 (m, 2H), 7.67 (d, J = 8.4 Hz, 1H), 7.40 (t, J = 6.9 Hz, 4H), 7.34-7.07 (m, 2H), 6.91 (dd, J =17.1, 8.9 Hz, 2H), 5.04 (d, J = 7.7 Hz, 2H), 4.47-4.34 (m, 3H), 4.19 (ddd, J= 21.1, 13.5, 5.8 Hz, 4H), 4.00-3.87 (m, 3H), 3.24-3.15 (m, 2H), 3.06 (d, J =19.8 Hz, 3H), 2.43 (s, 3H), 2.08-1.99 (m, 1H), 1.95-1.85 (m, 1H), 1.54 (t, J = 7.2 Hz, 3H), 0.93 (s, 9H). HRMS (ESI / Q-TOF) m / z of [M+H] + : Calcd forC 48 H 58 N7O7S + 876.4113; Found 876.4117. The NMR data of probe IV (D4) are shown in the figure. Figures 16-19 As shown, the high-performance liquid chromatography (HPLC) chromatogram is as follows: Figure 20 As shown.

[0034] 4. Synthesis of probe VI (F4) The synthetic route for probe VI (F4) is as follows: The probe VI (F4) was synthesized using a method similar to that described above.

[0035] (1) Compound D2 (48.0 mg, 1.0 equivalent) and triethylamine (36.3 µL, 3.0 equivalent) were dissolved in dichloromethane, and ethanolamine (10.6 mg, 3.0 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 24 hours, it was purified by column chromatography using dichloromethane / methanol (v / v 40:1) as the eluent to give a yellow oily product F1 (45.0 mg, yield 71%). HRMS (ESI / Q-TOF) m / z of [M+Na] + Calcd for C 16 H 23 N3NaO6 376.1477; Found376.1477. (2) Compound F1 (45.0 mg, 1.0 equivalent) and triethylamine (72.0 μL, 4.0 equivalent) were dissolved in 1.3 mL of dichloromethane, and 4-nitrobenzene chloroformate (38.5 mg, 1.5 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 8 hours, the crude product was purified by rapid column chromatography (FCC) using dichloromethane / methanol (40:1 v / v) as the eluent to obtain compound F2 (47.5 mg, yield 72%). HRMS (ESI / Q-TOF) m / z of [M+Na] + Calcd for C 23 H 26 N4NaO 10 541.1541; Found 541.1546. (3) VHL ligand 1 (18.8 mg, 1.0 equivalent) and compound F2 (25 mg, 1.2 equivalent) were dissolved in 0.5 mL DMF, and N-methylmorpholine (NMM, 26.0 μL, 6.0 equivalent) was added at 0 °C. After stirring the reaction solution at room temperature for 12 hours, the crude product was purified by column chromatography using dichloromethane / methanol (v / v 15:1) as the eluent to obtain product F3 (20.0 mg, yield 81%). HRMS (ESI / Q-TOF) m / z of [M+Na] + Calcd for C 39 H 51 N7NaO 10 S + 832.3310, Found 832.3292. (4) Compound F3 (20.0 mg, 1.0 equivalent) and A8 (4.3 mg, 1.0 equivalent) were dissolved in 1.0 mL of anhydrous methanol, a small amount of piperidine was added, and the mixture was heated under reflux for 2 hours. After the reaction was completed, all solvents were evaporated, and the crude product was washed with diethyl ether to obtain a purple powder product D4 (22.1 mg, yield 93%). 1 H NMR (400 MHz, DMSO- d 6) δ 8.97 (s, 1H), 8.81 (d, J = 9.1 Hz, 1H), 8.56 (dd, J = 20.0, 7.9 Hz, 2H), 8.44 (d, J = 9.2Hz, 1H), 8.31 (d, J = 15.4 Hz, 1H), 8.25 (d, J= 7.9 Hz, 1H), 8.09 (t, J =7.9 Hz, 1H), 7.86 (dd, J = 8.1, 5.2 Hz, 2H), 7.47 (d, J = 15.3 Hz, 1H), 7.40(t, J = 6.4 Hz, 4H), 7.29 (s, 1H), 7.19 (t, J = 5.8 Hz, 1H), 6.93 (d, J = 9.2Hz, 1H), 6.88 (d, J = 8.7 Hz, 2H), 5.16 (d, J = 3.6 Hz, 1H), 5.05 (d, J = 7.6Hz, 2H), 4.48-4.40 (m, 2H), 4.40-4.33 (m, 2H), 4.24 (d, J = 5.7 Hz, 1H), 4.16(t, J = 6.9 Hz, 3H), 3.93 (dd, J = 11.4, 6.2 Hz, 4H), 3.71 (d, J = 6.0 Hz, 3H), 3.18 (d, J = 5.6 Hz, 3H), 3.08 (s, 3H), 2.43 (s, 3H), 2.03 (d, J = 9.6Hz, 1H), 1.90 (dt, J = 12.4, 6.4 Hz, 1H), 1.54 (t, J = 7.2 Hz, 3H), 0.93 (s,9H). HRMS (ESI / Q-TOF) m / z of [M+H] + Calcd for Calcd for C 51 H 63 N8O9S + 963.4433, Found 963.4430. The NMR data of probe VI (F4) are shown in the figure. Figures 21-24 As shown, the high-performance liquid chromatography (HPLC) chromatogram is as follows: Figure 25 As shown.

[0036] The chemical structure diagrams of the above four probes are as follows: Figure 26 As shown.

[0037] Example 2 This embodiment provides the pharmaceutical application of the above-mentioned PROTAC compounds that target Aβ, specifically: PROTACs are used to prevent and treat Aβ-mediated Alzheimer's disease by promoting Aβ degradation at the cellular and in vivo levels.

[0038] (1) Preliminary screening results of the affinity of Aβ PROTACs to Aβ aggregates and their degradation effect on Aβ PROTAC molecules: Aβ monomers were fibrinolysed at 37°C for 72 h to obtain Aβ aggregates at a final concentration of 20 μM, and AβPROTACs at a final concentration of 25 μM. The total test volume was 200 μL, placed in black opaque 96-well plates. Fluorescence spectra of different concentrations of AβPROTACs and Aβ aggregates were measured using a multi-mode microplate reader at 37°C with an excitation wavelength of 580 nm. To preliminarily verify the ability of AβPROTACs to degrade Aβ in cells, Western blotting was used to measure protein changes. In 293T cells overexpressing APP (Aβ precursor protein), Aβ levels were quantified after treatment with 5 μM PROTACs for 24 hours.

[0039] See results Figure 27 . Figure 27 A shows that, except for compound A9 which has an affinity at the micromolar level, the binding affinity of compounds C3, D4, and F4 remains at the nanomolar level, indicating that the synthesized Aβ PROTACs have good targeting properties with Aβ aggregates. Figure 27 BE showed that 72 hours after APP transfection, the levels of APP and Aβ proteins were significantly higher than those in the control group. With comparable APP expression levels in each treatment group, compound D4 almost completely degraded intracellular poly-Aβ aggregates within 24 hours, while other PROTACs with different linkers showed relatively weak degradation efficiency.

[0040] (2) Dose-effect relationship of compound D4 in the degradation of Aβ: Compound D4 was selected as a representative Aβ PROTAC, and the relationship between concentration and degradation effect was further investigated within a fixed concentration range (0-10 μM).

[0041] See results Figure 28 Different concentrations of D4 were used to treat 293T cells overexpressing APP for 24 h. Figure 28 A showed that within the tested concentration range, Aβ levels in D4-treated cells decreased in a dose-dependent manner, with Dmax values ​​of 39% (multimer) and 80% (oligomer). Figure 28AC). When the concentration was >5 μM, a dose-dependent improvement in protein knockdown was observed ( Figure 28 C), this biphasic reaction indicates that the degradation depends on the formation of a PROTAC-mediated ternary complex (hook effect).

[0042] (3) Time-dependent relationship of compound D4 in the degradation of Aβ After treating Aβ-EGFP cells with 5 μM D4 for 0–48 h, Western blot analysis of Aβ multimers and oligomers was performed to further investigate the relationship between time and degradation efficiency.

[0043] See results Figure 29 The scavenging effect of D4 on Aβ was observable within 6 hours after treatment, reaching maximum degradation at 48 hours: the maximum degradation rate (Dmax) for polymeric Aβ was 59%, and for oligomers it was 61%. Figure 29 AC).

[0044] (4) Verification of the degradation mechanism of compound D4 for Aβ Cells were treated with 10 μM MG132 proteasome inhibitor or 0.1 μM BafA1 lysosomal inhibitor and 0.5 μM D4 for 24 hours. Aβ protein levels were detected by Western blotting to explore the D4-induced Aβ multimer clearance and degradation pathway.

[0045] See results Figure 30 After MG132 inhibits proteasome activity, D4-mediated Aβ oligomer degradation is cancelled. Figure 30 (AB), indicating that D4 enhances the proteasome's clearance of Aβ oligomers through ubiquitination. However, MG132 treatment selectively inhibited oligomer degradation without affecting multimer clearance (AB). Figure 30 C). This indicates that the degradation of the Aβ multimer is independent of the ubiquitin-proteasome system. This is likely because the folded structure of the Aβ multimer hinders its entry into the narrow 20S proteasome barrel, thus impeding proteasome degradation. Eukaryotic protein clearance is primarily achieved through two pathways—the ubiquitin-proteasome system and lysosomal proteolysis. We further confirm that D4 promotes multimer degradation via a lysosomal mechanism. Treatment with the lysosomal inhibitor Bafilomycin A1 (BafA1) canceled D4-mediated Aβ multimer clearance. Figure 30 These results indicate that D4 enhances Aβ multimer clearance via lysosomal degradation. Immunoprecipitation confirmed that D4 selectively increases K63 ubiquitination of Aβ multimers (DE). Figure 30The K63R mutation cancels D4-induced K63 ubiquitination, and K63-linked ubiquitination in the cell mediates lysosomal degradation. These results indicate that D4 enhances the degradation of various aggregate forms of Aβ aggregates by increasing the ubiquitin-proteasome and lysosomal degradation pathways.

[0046] (5) Compound D4 degrades Aβ protein in the brain of 5×FAD. Six-month-old 5×FAD mice were treated with intraperitoneal injections of 3 mg / kg D4 weekly for four weeks. After treatment, the mice were anesthetized, and their hearts were perfused with PBS. Hippocampal tissue was then harvested from the brain, and a mixture of ripa and protease inhibitors was added. The tissue was ground at low temperature and centrifuged at 12,000 rpm for 15 minutes. The supernatant was collected, and protein concentration was determined using the BCA assay. An equal volume of protein sample was boiled at 95°C for 10 minutes, and then separated in a 12% SDS-PAGE gel at 110V for 80 minutes. Finally, the protein was transferred to a polyvinylidene fluoride membrane at 300 mA for 130 minutes. The membrane was then blocked with 5% skim milk at 37°C for 1 hour, incubated with Aβ primary antibody at 4°C overnight, and incubated with the corresponding HRP-labeled secondary antibody at 37°C for 1 hour. ECL staining was then performed, and the results were analyzed using ImageJ software.

[0047] See results Figure 31 In 6-month-old 5×FAD mice, compared with the control group, the D4 treatment group showed a significant decrease in high molecular weight Aβ in brain tissue ( Figure 31 AC), indicating that D4 increased the degradation level of high molecular weight Aβ.

[0048] (6) Compound D4 treatment alleviates AD-related pathology Six-month-old 5×FAD mice were selected for treatment, receiving weekly intraperitoneal injections of 3 mg / kg D4 for four weeks. After treatment, the mice were anesthetized and then perfused with PBS and 4% PFA. The mice were fixed with 4% PFA for 24 h, and then sectioned on a vibratory microtome to a thickness of 30 μm. The sections were then blocked with PBS solution of 3% BSA + 0.3% Triton-100X at room temperature for 2 h. The mice were incubated overnight at 4°C with primary antibodies against the neuronal marker NeuN, the microglial marker IBA1, and the astrocyte marker GFAP. After incubation with the corresponding fluorescently labeled secondary antibodies at 37°C for 2 h, immunofluorescence imaging was performed, and the results were analyzed using ImageJ software.

[0049] See results Figure 32Neuronal density increased in the D4 treatment group compared to the control group. Subsequent examination of neuroinflammation levels revealed significantly reduced microglia and astrocyte activation levels in the brain tissue of 6-month-old mice treated with D4 compared to the control group. Therefore, D4 ​​treatment not only reduced Aβ burden but also improved various pathological features in AD model mice, suggesting that PROTAC therapy targeting Aβ is a potential treatment for delaying AD progression.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A PROTAC compound, characterized in that, Its structure is shown in the following formula (I): （I）； Wherein A is selected from one of the following formulas (II) to (V): (II)、 (‌III)、 (IV)、 （V）。 2. The PROTAC compound according to claim 1, characterized in that, The structure of A in the PROTAC compound is shown in the following formula (II): (II)。 3. The PROTAC compound according to claim 1, characterized in that, The structure of A in the PROTAC compound is shown in the following formula (III): (‌III)。 4. The PROTAC compound according to claim 1, characterized in that, The structure of A in the PROTAC compound is shown in the following formula (IV): (IV)。 5. The PROTAC compound according to claim 1, characterized in that, The structure of A in the PROTAC compound is shown in the following formula (V): （V）。 6. A method for preparing the PROTAC compound of claim 2, characterized in that, Includes the following steps: (1) React 4-acetaminobenzaldehyde with an aqueous sodium hydroxide solution in methanol to obtain 4-hydroxybenzaldehyde (A2); (2) The 4-hydroxybenzaldehyde (A2) obtained in step (1) is reacted with di-tert-butyl dicarbonate in anhydrous tetrahydrofuran in the presence of N,N-diisopropylethylamine to obtain 4-(tert-butyloxycarbonyloxy)benzaldehyde (A3). (3) The 4-(tert-butoxycarbonyloxy)benzaldehyde (A3) obtained in step (2) is reacted with iodomethane in anhydrous N,N-dimethylformamide in the presence of sodium hydride to obtain 4-(tert-butoxycarbonyloxy)-3-methoxybenzaldehyde (A4). (4) React the 4-(tert-butoxycarbonyloxy)-3-methoxybenzaldehyde (A4) obtained in step (3) with trifluoroacetic acid in dichloromethane to remove the protecting group and obtain 3-methoxy-4-hydroxybenzaldehyde (A5). (5) The 3-methoxy-4-hydroxybenzaldehyde (A5) obtained in step (4) is reacted with 2-bromoacetyl bromide in anhydrous dichloromethane in the presence of triethylamine to give 2-bromo-1-(3-methoxy-4-hydroxyphenyl) ethyl ketone (A6). (6) The 2-bromo-1-(3-methoxy-4-hydroxyphenyl) ethyl ketone (A6) obtained in step (5) is reacted with VHL ligand 1 in anhydrous acetonitrile in the presence of potassium carbonate and a catalytic amount of potassium iodide to obtain intermediate A7. (7) React the intermediate A7 obtained in step (6) with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

7. A method for preparing the PROTAC compound of claim 3, characterized in that, Includes the following steps: (1) Compound B4 is reacted with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to give activated ester C1; (2) The activated ester C1 obtained in step (1) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate C2; (3) The intermediate C2 obtained in step (2) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinolineonium salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile upon heating, and the structure of compound B4 is shown in formula (VI): (WE).

8. A method for preparing the PROTAC compound of claim 4, characterized in that, Includes the following steps: (1) The activated ester C1 obtained in step (1) of claim 7 is reacted with ethanolamine in dichloromethane in the presence of triethylamine to obtain intermediate D1; (2) The intermediate D1 obtained in step (1) is reacted with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to obtain activated ester D2; (3) The activated ester D2 obtained in step (2) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate D3; (4) The intermediate D3 obtained in step (3) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

9. A method for preparing the PROTAC compound of claim 5, characterized in that, Includes the following steps: (1) React the activated ester D2 obtained in step (2) of claim 8 with ethanolamine in dichloromethane in the presence of triethylamine to obtain intermediate F1; (2) React the intermediate F1 obtained in step (1) with 4-nitrobenzene chloroformate in dichloromethane in the presence of triethylamine to obtain intermediate F2; (3) The intermediate F2 obtained in step (2) is reacted with VHL ligand 1 in N,N-dimethylformamide in the presence of N-methylmorpholine to obtain intermediate F3; (4) The intermediate F3 obtained in step (3) is reacted with quinoline salt A8 in anhydrous methanol in the presence of piperidine to obtain the PROTAC compound; The quinoline salt A8 is prepared by reacting 2-methylquinoline with iodoethane in acetonitrile by heating.

10. The use of the PROTAC compound of claim 1 in the preparation of a degrading agent targeting Aβ aggregates, characterized in that, The degrading agent targeting Aβ aggregates comprises the PROTAC compound of any one of claims 1-5 and a pharmaceutically acceptable carrier.

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