Novel Indole-based HDAC6 Small Molecule Inhibitors, Preparation Methods and Applications

Abstract

This invention belongs to the field of compound synthesis technology, specifically relating to a novel indole-based HDAC6 small molecule inhibitor, its preparation method, and its applications. The novel indole-based HDAC6 small molecule inhibitor of this invention is a compound represented by Formula I or a pharmaceutically acceptable salt thereof. Experimental results show that, compared with the positive control vorinostat (SAHA), the novel indole-based HDAC6 small molecule inhibitor provided by this invention not only exhibits superior selective inhibition of HDAC6 protein but also inhibits the proliferation of gastric cancer cells in a concentration-dependent manner. Therefore, the compound of this invention has promising applications in the preparation of HDAC6-targeted inhibitors and drugs that inhibit the proliferation of gastric cancer cells, and is of great significance for the development of HDAC6-targeted inhibitors and anti-tumor drugs, as well as the research and treatment of related diseases.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, specifically relating to a novel indole-based HDAC6 small molecule inhibitor, its preparation method, and its application. Background Technology

[0002] Globally, cancer is the second leading cause of death after cardiovascular disease. Treatment methods for cancer mainly include surgery, radiotherapy, and chemotherapy. Currently, molecularly targeted therapy targets specific oncogenic sites at the cellular and molecular level, effectively intervening in signaling pathways closely related to cancer development and progression to achieve highly effective tumor treatment. Compared to traditional anti-tumor chemotherapy drugs, the rational use of targeted drugs can significantly reduce the side effects of chemotherapy, resulting in better cancer treatment outcomes.

[0003] Numerous studies have shown that the epigenetic modifications of histones, including acetylation and deacetylation, play crucial roles in many biological processes. Under the regulation of histone acetylation enzymes (HATs) and histone deacetylases (HDACs), the level of histone acetylation in the human body maintains a dynamic balance. However, studies have found high expression of HDACs in many tumor cells. Therefore, HDACs have remained a popular target for tumor-targeted therapy.

[0004] HDAC6, as a member of the class IIb histone deacetylase family, differs from other Zn... 2+ HDAC6, a type of HDAC-dependent inhibitor, possesses more distinct characteristics. Located in the cytoplasm, HDAC6 contains two catalytic domains (CD1 and CD2) and a ubiquitin-binding zinc finger domain, playing a crucial role in cancer, neurological disorders, inflammation, and other diseases. Existing research confirms that aberrant expression of HDAC6 is closely related to the development and progression of gastric cancer; its overexpression can induce the transformation of normal cells into gastric cancer cells, leading to cancer. Therefore, inhibiting HDAC6 activity can help prevent the development and progression of gastric cancer. However, there are currently few reported studies on the use of HDAC6 inhibitors for the treatment of gastric cancer.

[0005] Therefore, developing more potent and selective small-molecule HDAC6 inhibitors is of significant research value and application importance for the treatment and prognosis of gastric cancer. Summary of the Invention

[0006] To address the aforementioned problems, the primary objective of this invention is to provide a novel indole-based small molecule inhibitor of HDAC6, which not only exhibits superior selective inhibition of HDAC6 but also inhibits the proliferation of gastric cancer cells in a concentration-dependent manner.

[0007] The second objective of this invention is to provide a method for preparing the novel indole-based HDAC6 small molecule inhibitor described above. The third objective of this invention is to provide applications of the novel indole-based HDAC6 small molecule inhibitor described above.

[0008] To achieve the objective of this invention, the technical solution adopted is as follows:

[0009] A novel indole-based small molecule inhibitor of HDAC6, which is a compound of Formula I or a pharmaceutically acceptable salt thereof;

[0010]

[0011] In Formula I, R1 is selected from one of H, 5-CH3, 6-CH3, 7-CH3, 5-OCH3, 5-Br, 6-Br, and 6-OCH3;

[0012] R2 is selected from H, CH3, One of them;

[0013] R3 is H or CH3; R4 is selected from... One of OH.

[0014] Based on considerations of improving the inhibitory effect of compounds on HDAC6 and their inhibitory effect on the proliferation of gastric cancer cells, compounds with the following structures, referred to as compounds Z-1 to Z-55, are preferred options:

[0015]

[0016]

[0017]

[0018] The present invention discloses a method for preparing a novel indole-based HDAC6 small molecule inhibitor, characterized by the following technical route:

[0019]

[0020] When R2 is H and R4 is The preparation method of a novel indole-based HDAC6 small molecule inhibitor includes the following steps:

[0021] (1) Raw material A, raw material B, condensing agent a, and alkaline substance a are condensed in solvent a to obtain intermediate C;

[0022] (2) Intermediate C was reacted with hydroxylamine aqueous solution in solvent b, and then alkaline substance b was added to react. After the reaction was completed, acidic substance and water were added, and the mixture was filtered to obtain the novel indole HDAC6 small molecule inhibitor shown in compound M.

[0023] The preparation method of a novel indole-based HDAC6 small molecule inhibitor when R2 is H and R4 is OH includes the following steps:

[0024] s1. Raw material A, raw material B, condensing agent a, and basic substance a are condensed in solvent a to obtain intermediate C;

[0025] s2. Intermediate C and basic substance b are reacted in solvent c to obtain the novel indole-based HDAC6 small molecule inhibitor shown in compound J.

[0026] When R2 is not H and R4 is The preparation method of a novel indole-based HDAC6 small molecule inhibitor includes the following steps:

[0027] ①The raw material A, raw material B, condensing agent a, and basic substance a are condensed in solvent a to obtain intermediate C;

[0028] ② React intermediate C, alkaline substance c, and raw material a in solvent d to obtain intermediate E;

[0029] ③ React intermediate E with an aqueous solution of hydroxylamine in solvent b, then add alkaline substance b to continue the reaction. After the reaction is complete, add acidic substance and water, and filter to obtain the novel indole-based HDAC6 small molecule inhibitor shown in compound F.

[0030] When R2 is H and R4 is The preparation method of a novel indole-based HDAC6 small molecule inhibitor includes the following steps:

[0031] S1. Raw material A, raw material B, condensing agent a, and basic substance a are condensed in solvent a to obtain intermediate C;

[0032] S2. Intermediate C and basic substance b are reacted in solvent c to obtain compound J;

[0033] S3. Compound J, condensing agent b, and amine are reacted in solvent d to obtain intermediate K;

[0034] S4. Dissolve intermediate K in solvent f, and then add an acidic substance under stirring to react and obtain the novel indole-based HDAC6 small molecule inhibitor shown in compound L.

[0035] When R2 is not H and R4 is The preparation method of a novel indole-based HDAC6 small molecule inhibitor includes the following steps:

[0036] (i) Raw material A, raw material B, condensing agent a, and basic substance a are condensed in solvent a to obtain intermediate C;

[0037] (ii) Intermediate compound C, CuI, raw material b, and amine are reacted in solvent e to obtain intermediate E';

[0038] (iii) Intermediate E' and basic substance b are reacted in solvent d to obtain intermediate G;

[0039] (iv) Intermediate G, condensing agent b, and amine are reacted in solvent d to obtain intermediate H;

[0040] (v) The intermediate H was dissolved in solvent f, and then an acidic substance was added under stirring to react and obtain the novel indole-based HDAC6 small molecule inhibitor shown in compound I.

[0041] To improve the solubility of raw materials and the yield of products, preferably, solvent a is dichloromethane, solvent b is a mixed solution of dichloromethane and methanol, solvent c is a mixed solution of methanol and water, solvent d is N,N-dimethylformamide, solvent e is toluene, and solvent f is 1,4-dioxane.

[0042] As a preferred embodiment, the alkaline substance a is triethylamine, the alkaline substance b is sodium hydroxide, and the alkaline substance c is potassium hydroxide; the acidic substance is hydrochloric acid.

[0043] As a preferred embodiment, the condensing agent a is EDCI or HOBT; the condensing agent b is EDCI or DMAP; and the amine is N-Boc phenylenediamine.

[0044] As a preferred embodiment, raw material a is a brominated compound; raw material b is trans(1R,2R)-N,N'-dimethyl-1,2-cyclohexanediamine and anhydrous potassium phosphate.

[0045] The application of the novel indole-based HDAC6 small molecule inhibitor of the present invention is specifically in the preparation of inhibitors based on the HDAC6 target, or in the preparation of drugs for targeted cancer therapy based on the HDAC6 target.

[0046] Furthermore, the drug comprises at least one of the novel indole HDAC6 small molecule inhibitors and pharmaceutically acceptable excipients; the mass content of the novel indole HDAC6 small molecule inhibitor is preferably 90% to 98%; the present invention does not have any special limitation on excipients, and pharmaceutically acceptable excipients well known to those skilled in the art can be used.

[0047] As a preferred embodiment, the cancer is gastric cancer. Further, the drug is a drug that inhibits the proliferative activity of gastric cancer cells. The gastric cancer cells are MGC-803.

[0048] This invention provides a novel indole-based HDAC6 small molecule inhibitor with a novel structure and excellent inhibitory activity against HDAC6, making it suitable for use as an HDAC6 inhibitor. Furthermore, this type of compound inhibits the proliferative activity of gastric cancer cells by forming stable complexes through chelation with metal ions within the cells. The preparation method of the above-mentioned compounds provided by this invention is mild, easy to implement, and yields compounds with high yield and high purity. Experimental results show that, compared with the positive control vorinostat (SAHA), the novel indole-based HDAC6 small molecule inhibitor provided by this invention not only exhibits superior selective inhibition of HDAC6 protein but also inhibits the proliferation of gastric cancer cells (MGC-803) in a concentration-dependent manner. Therefore, the compounds of this invention have promising applications in the preparation of HDAC6-targeted inhibitors and drugs for inhibiting the proliferative activity of gastric cancer cells, and are of great significance for the development of HDAC6-targeted inhibitors and anti-tumor drugs, as well as the research and treatment of related diseases. Detailed Implementation

[0049] The present invention will be further described below with reference to specific embodiments, but this does not constitute a limitation on the present invention.

[0050] Example 1

[0051] Novel Indole-based HDAC6 Small Molecule Inhibitor Z-1 The preparation process is as follows:

[0052]

[0053] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The sample was then stirred with 100–200 mesh silica gel and packed into a 200–300 mesh silica gel column. The intermediate was purified using a (petroleum ether / ethyl acetate) solution as the mobile phase, with a yield of 93% and a purity of 97%.

[0054] (2) Dissolve 1 mmol of the intermediate obtained in step (1) in a DCM:MeOH = 2:1 solution, add 30 mmol of hydroxylamine aqueous solution (50% water) under stirring at 650 rpm at room temperature, stir at room temperature for 0.5 h, then add 10 mmol of sodium hydroxide and react for 10-30 min. After the reaction of the raw materials is complete, evaporate the organic solvent, add water to dissolve the system, then place it in an ice bath, add dilute hydrochloric acid to adjust the pH to 3-4, let it stand and filter, and then beat the obtained solid with ethyl acetate. Finally, dry to obtain the target compound Z-1 with a yield of 85%, a purity of 97%, a white solid, and a melting point of 199.9-201.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.58(s,1H),11.17(s,1H),9.00(s,1H),8.49(d,J=6.1Hz,1H),8.22-8.12(m,1H), 8.08(d,J=2.8Hz,1H),7.77-7.67(m,2H),7.42(dd,J=12.1,8.1Hz,3H),7.19-7.04(m,2H),4.52(d,J=6.0Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.12,164.64,144.28,136.62,131.60,128.35,127.49, 127.35,126.62,122.37,121.47,120.85,112.30,110.84,42.14.HR-MS(ESI):calcd.C 17 H 15 N3O3,[M+H]+m / z:310.1191,found:310.1194.

[0055] Example 2

[0056] Z-2, a novel indole-based small molecule inhibitor of HDAC6 The preparation process is as follows:

[0057]

[0058] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The sample was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The sample was then stir-fried with silica gel (100–200 mesh) and packed into a column (200–300 mesh). The intermediate was purified using a mobile phase of petroleum ether / ethyl acetate in a specific ratio; the yield was 93%, and the purity was 97%.

[0059] (2) Dissolve 1 mmol of the substance obtained in step (1) in DMF, add 3 mmol of potassium hydroxide and 2 mmol of methyl bromide while stirring at 650 rpm at room temperature, and react for 3-4 h. After the reaction is complete as monitored by TLC, extract three times with ethyl acetate and water. Wash the upper organic phase with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir-fry the sample, pack into a column, and separate and purify with petroleum ether / ethyl acetate as the mobile phase to obtain the intermediate; the yield is 93% and the purity is 97%.

[0060] (3) Dissolve 1 mmol of the substance obtained in step (2) in a DCM:MeOH = 2:1 solution, add 30 mmol of hydroxylamine aqueous solution (50% water) under stirring at 650 rpm at room temperature, stir at room temperature for 0.5 h, add 10 mmol of sodium hydroxide and react for 10-30 min. After the reaction of the raw materials is complete, evaporate the organic solvent, add water to dissolve the system, and then place it in an ice bath. Add dilute hydrochloric acid to adjust the pH to 3-4, let it stand and filter, and then beat the obtained solid with ethyl acetate. Finally, dry to obtain the target compound with a yield of 75%, a purity of 97%, a white solid, and a melting point of 193.0-193.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.17(s,1H),8.50(t,J=6.0Hz,1H),8.15(d,J=7.8Hz,1H),8.05(s,1H),7.71(d,J=8.0Hz,2H),7 .49(d,J=8.2Hz,1H),7.39(d,J=8.0Hz,2H),7.22(t,J=7.6Hz,1H),7.15(t,J=7.5Hz,1H),4.50(d,J=5.8Hz,2H),3.83(s,3H). 13C NMR (101MHz, DMSO-d6, ppm) δ164.75,164.66,144.23,137.22,132.36,131.62,127.49,127 .35,126.93,122.46,121.60,121.12,110.70,109.89,42.17,33.45.HR-MS(ESI):calcd.C 18 H 17 N3O3,[M+H]+m / z:324.1348,found:324.1349.

[0061] Example 3

[0062] Z-3, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with bromoethane, while the rest is the same as in Example 2. The compound with the structure shown in Formula Z-3 has a yield of 80%, is a white solid, and has a melting point of 207.0-207.3℃. 1 H NMR(400MHz,DMSO-d6,ppm)δ11.38-11.02(m,1H),9.00(s,1H),8.49(dt,J=6 .2,3.7Hz,1H),8.20-8.08(m,2H),7.71(dd,J=8.3,2.1Hz,2H),7.54(d,J=8.2 Hz, 1H), 7.40 (dd, J=8.3, 2.1Hz, 2H), 7.17 (dt, J=26.7, 7.0Hz, 2H), 4.52 (dd, J=14.2,5.8Hz,2H),4.24(qd,J=7.3,2.1Hz,2H),1.41(td,J=7.3,2.1Hz,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.79,164.65,144.22,136.29,131.63,130.64,127.70,127.56,12 7.36,127.10,122.41,121.73,121.11,110.71,110.03,42.18,41.21,15.59.HR-MS(ESI):calcd.C 19 H 19 N3O3,[M+H]+m / z:338.1504,found:338.1507.

[0063] Example 4

[0064] Z-4, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with bromopropane, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-4 is 78%, a white solid with a melting point of 203.0-203.4℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.16 (s, 1H), 8.97 (s, 1H), 8.46 (d, J = 6.1Hz, 1H),8.16(d,J=7.8Hz,1H),8.10(s,1H),7.75-7.67(m,2H),7.54(d,J=8.1H z,1H),7.41(d,J=8.0Hz,2H),7.17(dt,J=25.7,7.3Hz,2H),4.51(d,J=6.0H z, 2H), 4.17 (t, J = 6.9Hz, 2H), 1.81 (h, J = 7.2Hz, 2H), 0.87 (t, J = 7.3Hz, 3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.79,164.64,144.20,136.63,131.64,131.37,127.58,127.35,1 27.01,122.40,121.71,121.05,110.82,109.93,47.94,42.20,23.37,11.6.HR-MS(ESI):calcd.C 20 H 21 N3O3,[M+H]+m / z:352.1661,found:352.1662.

[0065] Example 5

[0066] Z-5, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with isobromopropane, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-5 is 76%, a white solid with a melting point of 189.9-191.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.49(d,J=6.1Hz,1H),8.33-8.10(m,2H),7.73(d,J=7.9Hz,2H),7.56(d,J=8.2Hz,1H),7. 42(d,J=7.9Hz,2H),7.17(dt,J=25.7,7.4Hz,2H),4.78(h,J=6.8Hz,1H),4.52(d,J=5.9Hz,2H),1.48(d,J=6.6Hz,6H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.90,164.60,144.13,136.09,131.64,127.65,127.35,12 7.13,122.38,121.75,121.19,110.82,110.07,47.41,42.19,22.89.HR-MS(ESI):calcd.C 20 H 21 N3O3,[M+H]+m / z:352.1661,found:352.1666.

[0067] Example 6

[0068] Z-6, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with isobromobutane, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-6 is 69%, a white solid with a melting point of 177.8-178.5℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.49(d,J=6.2Hz,1H),8.17(d,J=7.9Hz,1H),8.10(s,1H),7.72(d,J=7.9Hz,2H),7.53(d,J=8.2Hz,1H),7.40(d,J=7.9 Hz,2H),7.17(dt,J=26.6,7.3Hz,2H),4.51(d,J=5.8Hz,2H),4.20(t,J=7. 0Hz, 2H), 1.77 (p, J = 7.2Hz, 2H), 1.33-1.22 (m, 3H), 0.90 (t, J = 7.4Hz, 3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.82,164.45,144.04,136.58,131.72,131.31,127.57,127.28,127.0 0,122.43,121.71,121.07,110.78,109.92,46.06,42.19,32.08,19.92,13.98.HR-MS(ESI):calcd.C 21 H 23 N3O3,[M+H]+m / z:366.1817,found:366.1818.

[0069] Example 7

[0070] Z-7, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with bromomethylcyclopropane, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-7 is 67%, a white solid with a melting point of 177.7-178.7 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.51(t,J=6.0Hz,1H),8.23-8.13(m,2H),7.72(d,J=7.9Hz,2H),7.57(d,J=8.2Hz,1H),7 .40(d,J=7.9Hz,2H),7.17(dt,J=26.0,7.3Hz,2H),4.51(d,J=5.8Hz,2H),4.08(d,J=7.0Hz,2H),1.27(dd,J=15.9,6.8 Hz,1H),0.57(q,J=5.4,4.9 Hz,2H),0.42(t,J=5.0Hz,2H). 13 C NMR(101 MHz, DMSO-d6, ppm) δ164.82,164.54,144.20,136.67,131.65,131.07,127.56,127.33,126.99,122. 40,121.66,121.08,110.86,110.01,50.52,42.18,31.62,30.31,11.68,4.33.HR-MS(ESI):calcd.C 21 H 21 N3O3,[M+H]+m / z:364.1661,found:364.1666.

[0071] Example 8

[0072] Z-8, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that bromomethane in step (2) is replaced with benzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-8 is 87%, a white solid with a melting point of 137.1-137.9 °C. 1H NMR (400 MHz, DMSO-d6, ppm) δ11.20 (s, 1H), 9.01 (s, 1H), 8.58 (t, J = 6.0 Hz, 1H), 8.23-8.15 (m, 2H), 7.72 (d, J = 7.9 Hz, 2H), 7.54 (d, J = 8.0 Hz,1H),7.40(d,J=8.0 Hz,2H),7.34(t,J=7.2 Hz,2H),7.27(t,J=8.3 Hz,3H),7.21-7.10(m,2H),5.47(s,2H),4.50(d,J=5.7 Hz,2H). 13 C NMR(101 MHz, DMSO-d6, ppm) δ164.71,164.65,144.15,137.90,136.65,131.71,131.65,129.16,128.11,127.73 ,127.60,127.37,127.12,122.65,121.77,121.26,111.12,110.59,49.95,42.23.HR-MS(ESI):calcd.C 24 H 21 N3O3,[M+H]+m / z:400.1661,found:400.1666.

[0073] Example 9

[0074] Z-9, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 4-methoxybenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-9 is 72%, a white solid with a melting point of 146.7-147.6 °C. 1 H NMR (400 MHz, DMSO-d6, ppm) δ11.20 (s, 1H), 9.06 (d, J = 13.2 Hz, 1H), 8.55 (t, J = 6.0 Hz, 1H), 8.16 (d, J = 8.3 Hz, 2H), 7.72 (d, J = 7.8 Hz,2H),7.56(d,J=8.0 Hz,1H),7.41(d,J=8.0 Hz,2H),7.30-7.10(m,4H),6.90(d,J=8.2 Hz,2H),5.37(s,2H),4.51(d,J=6.0 Hz,2H),3.71(s,3H). 13C NMR(101 MHz, DMSO-d6, ppm) δ164.79,159.25,144.15,136.54,131.59,131.50,129.65,129.32,127.60,127.35 ,127.13,122.59,121.71,121.24,114.53,111.16,110.39,55.55,49.47,42.21.HR-MS(ESI):calcd.C 25 H 23 N3O4,[M+H]+m / z:430.1767,found:430.1768.

[0075] Example 10

[0076] Z-10, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that in Example 2 in that bromomethane in step (2) is replaced with 4-methylbenzyl bromide. Compound Z-10 has a yield of 66%, is a white solid, and has a melting point of 131.6-132.0 °C. 1 H NMR (400 MHz, DMSO-d6, ppm) δ11.19 (s, 1H), 9.01 (s, 1H), 8.55 (t, J = 6.0 Hz, 1H), 8.27-8.04 (m, 2H), 7.71 (d, J = 8.0 Hz, 2H), 7.53 (d, J = 8.0 Hz,1H),7.40(d,J=8.0 Hz,2H),7.14(p,J=7.3,6.6 Hz,7H),5.41(s,2H),4.52(dd,J=13.8,5.9Hz,2H),2.25(s,3H). 13 C NMR(101 MHz, DMSO-d6, ppm) δ164.72,144.15,137.36,136.61,134.80,131.64,129.68,127.81,127.59,12 7.35,127.15,122.57,121.75,121.21,111.13,110.48,49.77,42.21,21.13.HR-MS(ESI):calcd.C 25 H 23 N3O3,[M+H]+m / z:414.1817,found:414.1818.

[0077] Example 11

[0078] Z-11, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 2-methylbenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-11 is 55%, a white solid with a melting point of 189.5-190.7℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.57(d,J=6.3Hz,1H),8.17(d,J=7.5Hz,1H),7.97(s,1H),7.68(d,J=7.8Hz,2H),7.46(d,J=7.6Hz,1H),7.38(d,J =7.9Hz,2H),7.18(dq,J=13.4,7.8,7.0Hz,4H),7.09(t,J=7.5Hz,1H),6.73(d,J=7.7Hz,1H),5.43(s,2H),4.48(d,J=5.9Hz,2H),2.27(s,3H). 13 CNMR(101MHz,DMSO-d6,ppm)δ164.68,164.49,144.08,136.97,136.37,135.68,131.70,131.44,130.83,128.15,127.7 1,127.56,127.30,127.03,126.63,122.67,121.86,121.30,111.05,110.60,48.07,42.18,19.24.HR-MS(ESI):calcd.C 25 H 23 N3O3,[M+H]+m / z:414.1817,found:414.1822.

[0079] Example 12

[0080] Z-12, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that in Example 2 in that the bromomethane in step (2) is replaced with 3-methylbenzyl bromide. The yield of the structure shown in Formula Z-12 is 67%, a white solid with a melting point of 110.0-111.3℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.18(s,1H),8.99(s,1H),8.56(t,J=6.0Hz,1H),8.17(d,J=7.9Hz,2H),7.77-7.68(m,2 H),7.53(d,J=8.0Hz,1H),7.41(d,J=7.9Hz,2H),7.26-7.01(m,6H),5.42(s,2H),4.50(d,J=5.8Hz,2H),2.26(s,3H).13 CNMR(101MHz,DMSO-d6,ppm)δ164.71,144.14,138.34,137.81,136.67,131.69,129.08,128.80,128.32,127.5 9,127.35,127.10,124.90,122.63,121.75,121.24,111.11,110.53,49.96,42.22,21.47.HR-MS(ESI):calcd.C 25 H 23 N3O 3, [M+H]+m / z:414.1817,found:414.1823.

[0081] Example 13

[0082] Z-13, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 4-fluorobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-13 is 69%, a white solid with a melting point of 141.1-142.2 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.43-10.89(m,1H),9.05(s,1H),8.57(t,J=5.9Hz,1H),8.17(d,J=8.9Hz,2H),7.72(d,J=7.8Hz,2H),7.55( d,J=8.0Hz,1H),7.40(d,J=7.9Hz,2H),7.32(dd,J=8.4,5.5Hz,2H),7.17(td,J=8.3,7.5,3.3Hz,4H),5.46(s,2H),4.50(d,J=5.9Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.68,163.28,160.85,144.14,136.55,134.09,134.06,131.65,131.59,129.95,129.87 ,127.60,127.37,127.14,122.68,121.78,121.30,116.07,115.86,111.08,110.69,49.17,42.22.HR-MS(ESI):calcd.C 24 H 20 FN3O3,[M+H]+m / z:418.1567,found:418.1573.

[0083] Example 14

[0084] Z-14, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 4-cyanobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Z-14 is 59%, a white solid with a melting point of 198.9-201.3 °C. 1 H NMR(400MHz,DMSO-d6,ppm)δ11.58(s,1H),9.00(s,1H),8.52(dt,J=19.4,5.9Hz,1 H),8.18(d,J=8.7Hz,1H),7.83(d,J=7.9Hz,1H),7.72(d,J=7.9Hz,2H),7.63(d,J=7 .9Hz,1H),7.52(t,J=7.5Hz,1H),7.41(d,J=8.2Hz,2H),7.31(t,J=8.8Hz,1H),7.25 (d,J=7.8Hz,1H),7.21-7.07(m,2H),5.50(d,J=18.5Hz,2H),4.52(t,J=5.0Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ168.00,165.12,164.69,144.28,141.00,136.62,133.27,133.14,131.73,128.44,128.35,127.61,127.49,127 .35,127.13,126.62,126.19,122.71,122.36,121.78,121.47,121.33,120.84,112.30,111.12,110.83,42.24,42.14.HR-MS(ESI):calcd.C 25 H 20 N4O3,[M+H]+m / z:425.1613,found:425.1614.

[0085] Example 15

[0086] Z-15, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that in Example 2 in that the bromomethane in step (2) is replaced with 3-cyanobenzyl bromide. The yield of the structure shown in Z-15 is 56%, a white solid with a melting point of 155.7-156.6 °C. 1H NMR (400MHz, DMSO-d6, ppm) δ11.17(s,1H),8.98(s,1H),8.57(t,J=6.2Hz,1H),8.26-8.14(m,2H),7.79(d,J=7.6Hz,1H),7.71(d,J =8.0Hz,2H),7.62-7.49(m,2H),7.39(dd,J=13.4,7.4Hz,4H),7.16(p,J=7.2Hz,2H),5.50(d,J=8.1Hz,2H),4.50(d,J=5.7Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ168.05,164.69,144.13,138.05,136.63,135.18,131.81,131.73,131.65,130.56,129.84,129.19,129.09 ,127.63,127.60,127.37,127.21,127.14,127.06,122.70,121.79,121.31,111.10,110.70,110.66,49.85,42.23.HR-MS(ESI):calcd.C 25 H 20 N4O3,[M+H]+m / z:425.1613,found:425.1614.

[0087] Example 16

[0088] Z-16, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 2-cyanobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-16 is 45%, it is a white solid with a melting point of 149.1-151.7℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.18(s,1H),8.99(s,1H),8.58(dd,J=15.4,9.5H z,1H),8.17(dd,J=27.1,6.2Hz,2H),7.93(d,J=7.8Hz,1H),7.68(dd,J=31.0,7. 7Hz,3H),7.52(t,J=7.3Hz,1H),7.44-7.36(m,2H),7.36-7.31(m,1H),7.24-7. 11(m,2H),7.06(d,J=7.9Hz,1H),5.68(d,J=16.3Hz,2H),4.50(d,J=5.9Hz,2H). 13C NMR(101MHz,DMSO-d6,ppm)δ170.84,164.73,164.65,144.15,136.79,135.88,135.81,133.88,132.20,131.64,130.57,129.84,128.56,128 .26,128.01,127.92,127.74,127.60,127.49,127.36,127.10,122.69,121.75,121.28,111.01,110.58,47.61,42.24.HR-MS(ESI):calcd.C 25 H 20 N4O3,[M+H]+m / z:425.1613,found:425.1616.

[0089] Example 17

[0090] Z-17, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 2-nitrobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Z-17 is 43%, a pale yellow solid with a melting point of 157.8-158.1℃. 1 H NMR (400 MHz, DMSO-d6, ppm) δ11.19(s,1H),9.01(s,1H),8.60(t,J=5.8 Hz,1H),8.25-8.14(m,2H),8.11(s,1H),7.72(d,J=7.9 Hz,2H),7.60(dt,J=22.1,7.5 Hz,2H),7.44(dd,J=23.7,6.5 Hz,3H),7.23-7.13(m,2H),6.62(d,J=7.6 Hz,1H),5.88(s,2H),4.51(d,J=5.8 Hz,2H). 13 C NMR(101 MHz, DMSO-d6, ppm) δ164.65,147.77,144.08,136.89,134.85,133.44,132.00,131.61,129.43,128.74,127 .62,127.35,126.99,125.65,123.01,121.85,121.60,111.20,111.14,47.52,42.23.HR-MS(ESI):calcd.C 24 H 20 N4O5,[M+H]+m / z:445.1512,found:445.1515.

[0091] Example 18

[0092] Z-18, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 3-nitrobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-18 is 57%, a pale yellow solid with a melting point of 165.9-167.3℃. 1 H NMR (400 MHz, DMSO-d6, ppm) δ11.18 (s, 1H), 8.99 (s, 1H), 8.57 (t, J = 6.1 Hz, 1H), 8.28-8.11 (m, 4H), 7.73 (d, J = 8.0 Hz,2H),7.68-7.61(m,2H),7.57(d,J=8.1 Hz,1H),7.44(dd,J=20.5,7.9 Hz,2H),7.18(p,J=7.0Hz,2H),5.66(s,2H),4.52(d,J=6.1 Hz,2H). 13 C NMR(101 MHz, DMSO-d6, ppm) δ164.63,148.43,144.08,140.24,136.56,134.34,131.69,130.83,129.84,127.74,127 .60,127.37,127.12,123.15,122.90,122.42,121.85,121.48,111.05,49.03,42.24.HR-MS(ESI):calcd.C 24 H 20 N4O5, [M+H] + m / z:445.1512,found:445.1513.

[0093] Example 19

[0094] Z-19, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the bromomethane in step (2) is replaced with 4-nitrobenzyl bromide, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-19 is 62%, a pale yellow solid with a melting point of 172.9-174.1℃. 1H NMR (400 MHz, DMSO-d6, ppm) δ8.58 (dq, J=12.3, 6.2 Hz, 1H), 8.31-8.15 (m, 3H), 7.92 (d, J=7.9 Hz,1H),7.72(d,J=7.8Hz,1H),7.61-7.37(m,4H),7.37-7.24(m,2H),7.15(ddt,J=22.3,14.7,6.4 Hz,2H),5.81-5.39(m,2H),4.57-4.48(m,2H). 13 C NMR (101MHz, DMSO-d6, ppm) δ167.70,164.61,147.45,146.01,145.67,137.9 0,136.60,131.81,131.64,129.84,129.63,129.54,129.15,128.71,128.11 ,127.76,127.73,127.62,127.36,127.14,124.37,122.89,122.64,121.87, 121.77,121.48,119.89,111.03,49.95,49.26,42.26.HR-MS(ESI):calcd.C 24 H 20 N4O5,[M+H]+m / z:445.1512,found:445.1513.

[0095] Example 20

[0096] Novel Indole-based HDAC6 Small Molecule Inhibitor Z-20 The preparation process is as follows:

[0097]

[0098] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using (100–200 mesh) silica gel and (200–300 mesh) sample-grade silica gel. The intermediate was purified using a (petroleum ether / ethyl acetate) solution as the mobile phase; the yield was 93%, and the purity was 97%.

[0099] (2) Dissolve 1 mmol of the substance obtained in step (1) and 0.6 mmol of anhydrous potassium phosphate in toluene, add the solution while stirring at 650 rpm at room temperature, then add 1.2 mmol of bromobenzene, 0.3 mmol of catalyst CuI and 2.1 mmol of trans-(1R,2R)-N,N-dimethyl-1,2-cyclohexanediamine, and react in an oil bath at 110 °C for 4-5 h under nitrogen protection. After the reaction is completed, the system is extracted three times with ethyl acetate and water, the upper organic phase is washed with saturated NaCl solution, dried with anhydrous sodium sulfate, and the organic phase is evaporated to dryness. Silica gel is added to fry the sample, and the sample is packed into a column. Petroleum ether / ethyl acetate is used as the mobile phase for separation and purification to obtain an intermediate with a yield of 93% and a purity of 97%.

[0100] (3) Dissolve 1 mmol of the substance obtained in step (2) in a DCM:MeOH = 2:1 solution, add 30 mmol of hydroxylamine aqueous solution (50% water) under stirring at 650 rpm at room temperature, stir at room temperature for 0.5 h, then add 10 mmol of sodium hydroxide and react for 10-30 min. After the reaction of the raw materials is complete, evaporate the organic solvent, add water to dissolve the system, then place it in an ice bath, add dilute hydrochloric acid to adjust the pH to 3-4, let it stand and filter, and then beat the obtained solid with ethyl acetate. Finally, dry to obtain the target compound Z-20 with a yield of 73%, a white solid with a melting point of 129.8-131.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.21(s,1H),9.02(s,1H),8.72(t,J=6.0Hz,1H),8.42(s,1H),8.36-8.14(m,1H),7.73(d,J=8.0Hz,2H),7.6 8-7.60(m,4H),7.57-7.52(m,1H),7.49(dp,J=5.3,2.4Hz,1H),7.44(d,J=8.0Hz,2H),7.26(tt,J=7.7,5.8Hz,2H),4.55(d,J=5.8Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.69,164.51,145.87,143.93,138.80,136.05,131.69,131.15,130.48,129.86,129.70, 127.88,127.80,127.76,127.61,127.39,124.70,123.64,122.19,122.13,112.33,111.17,42.24.HR-MS(ESI):calcd.C 23 H 19 N3O3,[M+H]+m / z:386.1504,found:386.1515.

[0101] Example 21

[0102] Z-21, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 4-methoxybromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-21 is 75%, a white solid with a melting point of 177.8-179.3℃. 1 H NMR(400MHz,DMSO-d6,ppm)δ8.65(t,J=6.1Hz,1H),8.36-8.22(m,2H),7.73(d,J=8.0Hz,2H), 7.60-7.50(m,2H),7.47-7.38(m,3H),7.29-7.11(m,4H),4.54(d,J=5.7Hz,2H),3.85(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.57,158.90,143.80,136.52,131.64,131.34,127.57,127.49,127 .32,126.34,123.44,122.08,121.90,115.53,111.77,111.06,55.99,42.23.HR-MS(ESI):calcd.C 24 H 21 N3O4,[M+H]+m / z:416.1610,found:416.1619.

[0103] Example 22

[0104] Z-22, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 4-methylbromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-22 is 68%, a white solid with a melting point of 121.4-122.8℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.19(s,1H),8.98(s,1H),8.69(t,J=6.1Hz,1H),8.38(s,1H),8.31-8.22(m,1H),7.73(d,J= 8.0Hz,2H),7.51(t,J=7.2Hz,3H),7.43(d,J=7.9Hz,4H),7.24(tt,J=7.7,5.8Hz,2H),4.54(d,J=5.8Hz,2H),2.41(s,3H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.63,164.54,143.95,137.40,136.31,136.18,131.71,131.10,130.86,129.87 ,127.69,127.60,127.40,124.59,123.54,122.14,122.02,112.08,111.16,42.25,21.09.HR-MS(ESI):calcd.C 24 H 21 N3O3,[M+H]+m / z:400.1661,found:400.1668.

[0105] Example 23

[0106] Z-23, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 3-methylbromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-23 is 46%, a white solid with a melting point of 159.6-161.7℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.69(t,J=6.0Hz,1H),8.39(s,1H),8.33-8.24(m,1H),7.74(d,J=7.9Hz,2H),7.56(d,J=7. 8Hz, 1H), 7.51 (t, J = 7.7Hz, 1H), 7.44 (t, J = 7.9Hz, 4H), 7.26 (dq, J = 13.2, 7.0Hz, 3H), 4.55 (d, J = 5.9Hz, 2H), 2.43 (s, 3H). 13 C NMR (101MHz, DMSO-d6, ppm) δ164.54,143.79,140.22,138.73,136.03,131.05,130.23,128.52,127.75,127 .60,127.33,125.10,123.62,122.15,122.10,121.68,112.19,111.27,42.25,21.39.HR-MS(ESI):calcd.C 24 H 21 N3O3,[M+H]+m / z:400.1661,found:400.1668.

[0107] Example 24

[0108] Z-24, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 3-cyanobromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-24 is 67%, a white solid with a melting point of 190.5-191.3℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.22(s,1H),8.75(q,J=6.2Hz,1H),8.47(d,J=5.5Hz,1H),8.29(d,J=7.5Hz,1H),8.19-8.09(m,2H),7.94(t,J=9.3 Hz,1H),7.84-7.69(m,3H),7.64(d,J=7.7Hz,1H),7.54-7.47(m,1H),7.44(d,J=7.9Hz,1H),7.29(p,J=7.0Hz,2H),4.57(dd,J=13.8,5.7Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.56,164.44,143.84,141.11,135.80,133.18,131.67,130.89,129.88,129.81, 127.95,127.77,127.63,127.39,124.34,123.99,122.43,122.24,112.87,111.35,42.26.HR-MS(ESI):calcd.C 24 H 18 N4O3,[M+H]+m / z:411.1457,found:411.1458.

[0109] Example 25

[0110] Z-25, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 4-cyanobromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-25 is 61%, a white solid with a melting point of 197.7-198.3℃. 1H NMR (400MHz, DMSO-d6, ppm) δ8.74(q,J=6.6Hz,1H),8.44(d,J=5.5Hz,1H),8.29(d,J=7.5Hz,1H),7.96(d,J=24.8Hz,1H),7.88-7.76 (m,1H),7.73(d,J=7.9Hz,2H),7.68-7.57(m,2H),7.44(d,J=7.9Hz,2H),7.27(q,J=7.2Hz,2H),6.00(s,1H),4.56(d,J=5.9Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.54,150.64,143.84,138.69,135.97,135.62,131.69,131.05,130.37,127.77, 127.62,127.37,124.95,124.73,123.85,123.76,122.20,121.40,112.46,111.23,42.27.HR-MS(ESI):calcd.C 24 H 18 N4O3,[M+H]+m / z:411.1457,found:411.1458.

[0111] Example 26

[0112] Z-26, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 2-cyanobromobenzene, while the rest is the same as in Example 2. The resulting solid with the structure shown in Formula Z-26 has a yield of 57%, is a white solid, and has a melting point of 178.9-180.3°C. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.83-8.49(m,1H),8.44-8.27(m,1H),8.15(d,J=7.2Hz,1H ),7.95(d,J=7.8Hz,1H),7.82-7.63(m,4H),7.43-7.10(m,6H),4.53(d,J=10.7Hz,2H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.21,140.53,136.95,135.54,135.09,131.57,129.80,128.89,127.44, 127.25,126.99,123.94,122.50,122.25,116.56,113.26,111.14,110.09,42.33.HR-MS(ESI):calcd.C 24 H 18 N4O3,[M+H]+m / z:411.1457,found:411.1458.

[0113] Example 27

[0114] Z-27, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 2-nitrobromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-27 is 35%, a yellowish-brown solid with a melting point of 159.7-161.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.19 (s, 1H), 9.03 (s, 1H), 8.67 (dt, J = 20.9, 6.3Hz ,1H),8.40(s,1H),8.28(t,J=6.8Hz,1H),8.21-8.12(m,1H),7.89(dd,J=28.7,8 .0Hz,1H),7.73(d,J=7.9Hz,2H),7.64(d,J=4.4Hz,2H),7.55(d,J=7.4Hz,1H),7 .52-7.39(m,2H),7.24(dp,J=15.7,6.2,5.4Hz,2H),4.55(p,J=9.5,7.6Hz,2H). 13 C NMR (101MHz, DMSO-d6, ppm) δ164.54,143.91,138.76,136.05,131.66,131.08,130.49,127.91, 127.74,127.61,127.38,124.70,123.69,122.16,112.30,111.18,42.25.HR-MS(ESI):calcd.C 23 H 18 N4O5,[M+H]+m / z:431.1355,found:431.1358.

[0115] Example 28

[0116] Z-28, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 3-nitrobromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-28 is 58%, a pale yellow solid with a melting point of 176.8-178.3℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.21 (s, 1H), 9.06 (s, 1H), 8.73 (d, J = 24.9Hz, 1H),8.51(s,1H),8.42(d,J=9.9Hz,1H),8.30(d,J=8.1Hz,2H),8.17(d,J=8 .1Hz,1H),7.93(d,J=8.0Hz,1H),7.74(d,J=7.8Hz,2H),7.66(d,J=8.4Hz,1 H),7.45(d,J=7.9Hz,2H),7.29(dt,J=17.2,8.8Hz,2H),4.68-4.40(m,2H). 13 CNMR(101MHz,DMSO-d6,ppm)δ164.58,164.46,164.34,143.77,141.69,139.67,135.80,131.99,131.71,130.94,130.78,127.96 ,127.63,127.40,124.69,124.17,122.67,122.33,122.28,121.08,119.12,115.30,113.31,111.07,42.27.HR-MS(ESI):calcd.C 23 H 18 N4O5,[M+H]+m / z:431.1355,found:431.1358.

[0117] Example 29

[0118] Z-29, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 4-nitrobromobenzene, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-29 is 60%, a yellow solid with a melting point of 179.5-180.0℃. 1H NMR (400MHz, DMSO-d6, ppm) δ11.19(s,1H),8.99(s,1H),8.77(q,J=5.6Hz,1H) ,8.51(s,1H),8.35-8.27(m,1H),8.16(d,J=8.7Hz,1H),7.92-7.81(d,J=7.9H z,2H),7.76-7.71(m,1H),7.65(d,J=7.9Hz,1H),7.55-7.47(m,1H),7.44(dd, J=8.0,3.4Hz,1H),7.30(tp,J=14.2,7.1Hz,2H),4.57(dd,J=11.8,7.8Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.51,164.17,145.82,144.23,143.70,135.56,131.77,130.74,130.48,129.84,128.33, 127.64,127.41,126.33,126.08,124.67,124.34,122.93,122.44,121.07,113.98,111.50,42.31.HR-MS(ESI):calcd.C 23 H 18 N4O5,[M+H]+m / z:431.1355,found:431.1358.

[0119] Example 30

[0120] Z-30, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that bromobenzene in step (2) is replaced with 4-bromophenol, while the rest is the same as in Example 2. The yield of the structure shown in Formula Z-30 is 20%, a pale purple solid with a melting point of 160.5-161.2℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.21(s,1H),9.91(s,1H),9.04(s,1H),8.65(t,J=6.0Hz,1H),8.27(d,J=11.2Hz,2 H),7.73(d,J=7.8Hz,2H),7.42(t,J=7.3Hz,5H),7.28-7.16(m,2H),6.99(d,J=8.2Hz,2H),4.54(d,J=5.8Hz,2H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.65,157.30,144.00,136.61,131.64,131.39,130.14,127.59, 127.37,126.44,123.34,122.00,121.81,116.74,111.47,111.11,42.21.HR-MS(ESI):calcd.C 23 H 19 N3O4,[M+H]+m / z:402.1454,found:402.1460.

[0121] Example 31

[0122] Z-31, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that bromobenzene in step (2) is replaced with 4-bromobenzyl alcohol, while the rest is the same as in Example 2. The yield of Z-31 is 66%, a white solid with a melting point of 164.9-165.6 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.25(s,1H),9.09(s,1H),8.73(t,J=6.2Hz,1H),8.34(s,1H),8.26(d,J=7.5Hz,1H),7.71(d,J=8.0Hz, 2H),7.54(dd,J=18.8,5.3Hz,5H),7.43(d,J=7.9Hz,2H),7.25(p,J=7.0Hz,2H),5.50(d,J=5.8Hz,1H),4.57(dd,J=24.7,5.0Hz,4H). 13 C NMR (101MHz, DMSO-d6, ppm) δ164.65,157.30,144.00,136.61,131.64,131.39,130.14,127.59,127 .37,126.44,123.34,122.00,121.81,116.74,111.47,111.11,45.77,42.21.HR-MS(ESI):calcd.C 24 H 21 N3O4,[M+H]+m / z:416.1610,found:416.1615.

[0123] Example 32

[0124] Z-32, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 3-bromofuran, while the rest is the same as in Example 2. The yield of the structure shown in Formula 32 is 77%, a white solid with a melting point of 185.9-187.4 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.65(d,J=6.1Hz,1H),8.36(s,2H),8.26(d,J=7.8Hz,1H),7.90(d,J=1.9Hz,1H),7.74(d,J=8.0Hz ,2H),7.61(d,J=8.2Hz,1H),7.43(d,J=8.0Hz,2H),7.28(dt,J=21.2,7.3Hz,2H),7.03(d,J=1.9Hz,1H),4.55(d,J=5.8Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ164.46,164.35,144.75,143.78,136.04,135.26,131.80,130.79,127.60, 127.49,127.35,126.76,123.77,122.18,122.05,112.24,111.59,107.69,42.26.HR-MS(ESI):calcd.C 21 H 17 N3O4,[M+H]+m / z:376.1297,found:376.1298.

[0125] Example 33

[0126] Z-33, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 20 in that the bromobenzene in step (2) is replaced with 3-bromothiophene, while the rest is the same as in Example 2. The compound of formula Z-33 has a yield of 70%, is a white solid, and has a melting point of 188.4-189.3℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.22(s,1H),8.74(t,J=6.0Hz,1H),8.43(s,1H),8.26(d,J=7.7Hz,1H),7.83(d,J=4.9Hz,2H),7.73(d,J =8.0Hz,2H),7.62(d,J=8.1Hz,1H),7.49(d,J=4.9Hz,1H),7.43(d,J=7.9Hz,2H),7.27(dt,J=19.9,7.2Hz,2H),4.54(d,J=5.9Hz,2H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.50,143.92,137.18,136.13,131.63,131.12,128.15,127.62,127 .44,127.38,123.94,123.76,122.18,122.04,116.88,111.95,111.48,42.24.HR-MS(ESI):calcd.C 21 H 17 N3O3S,[M+H]+m / z:392.1069,found:392.1075.

[0127] Example 34

[0128] Z-34, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 5-methylindole-3-carboxylic acid, while the rest is the same as in Example 1. Z-34 yield is 68%, white solid, melting point 186.8-187.7℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.49(d,J=2.9Hz,1H),11.19(s,1H),9.03(s,1H),8.48(t,J=6.0Hz,1H),8.02(d,J=2.8Hz,1H),7.96 (s,1H),7.72(d,J=7.9Hz,2H),7.40(d,J=7.9Hz,2H),7.32(d,J=8.3Hz,1H),7.01-6.95(m,1H),4.51(d,J=5.9Hz,2H),2.39(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.24,144.35,134.97,131.54,129.44,128.36,127.50 ,127.33,126.83,123.91,121.11,111.94,110.32,42.13,21.80.HR-MS(ESI):calcd.C 18 H 17 N3O3,[M+H]+m / z:324.1348,found:324.1349.

[0129] Example 35

[0130] Z-35, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 6-methylindole-3-carboxylic acid, while the rest is the same as in Example 1. The yield of Z-35 is 66%, a white solid with a melting point of 171.5-172.0 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.57-11.32(m,1H),11.19(s,1H),9.16-8.87(m,1H),8.48(t,J=6.2Hz,1H),8.06-7.93(m, 2H),7.71(d,J=7.9Hz,2H),7.39(d,J=7.9Hz,2H),7.22(s,1H),6.93(d,J=8.1Hz,1H),4.50(d,J=5.9Hz,2H),2.39(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.17,164.56,144.24,137.06,131.69,131.45,127.76,127 .48,127.31,124.49,122.61,121.15,112.04,110.74,42.13,21.77.HR-MS(ESI):calcd.C 18 H 17 N3O3,[M+H]+m / z:324.1348,found:324.1350.

[0131] Example 36

[0132] Z-36, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that indole-3-carboxylic acid in step (1) is replaced with 6-methylindole-3-carboxylic acid, and bromobenzene in step (2) is replaced with benzyl bromide. The rest is the same as in Example 2. The yield of Z-36 is 72%, a white solid with a melting point of 184.1-184.3℃. 1 H NMR(600MHz,DMSO-d6,ppm)δ11.16(s,1H),8.98(s,1H),8.48(t,J=6.1Hz,1 H),8.08(d,J=1.4Hz,1H),8.04(d,J=8.0Hz,1H),7.72-7.68(m,2H),7.39(d ,J=8.0Hz,2H),7.36-7.32(m,3H),7.29-7.25(m,1H),7.25-7.21(m,2H),6. 97(dd,J=8.2,1.4Hz,1H),5.42(s,2H),4.49(d,J=6.0Hz,2H),2.38(s,3H).13 C NMR(101MHz,DMSO-d6,ppm)δ164.76,164.65,144.18,138.01,137.09,131.92,131.64,131.13,129.16,12 8.06,127.61,127.36,124.98,123.02,121.49,110.76,110.56,49.76,42.22,21.91.HR-MS(ESI):calcd.C 25 H 23 N3O3,[M+H]+m / z:414.1817,found:414.1828.

[0133] Example 37

[0134] Z-37, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 7-methylindole-3-carboxylic acid, while the rest is the same as in Example 1. Z-37 yield is 60%, white solid, melting point 157.8-158.6℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.59(d,J=3.0Hz,1H),11.17(s,1H),8.98(s,1H),8.50(t,J=6.0Hz,1H),8.10(d,J=2.9Hz,1H),7.97(d,J=7 .9Hz,1H),7.72(d,J=8.0Hz,2H),7.40(d,J=8.0Hz,2H),7.00(t,J=7.5Hz,1H),6.94(d,J=7.0Hz,1H),4.51(d,J=5.9Hz,2H),2.47(s,3H). 13 C NMR (101MHz, DMSO-d6, ppm) δ165.18,144.29,136.16,131.61,129.80,128.07,127.51,127 .35,126.36,122.84,121.39,121.05,119.09,111.19,42.14,17.12.HR-MS(ESI):calcd.C 18 H 17 N3O3,[M+H]+m / z:324.1348,found:324.1355.

[0135] Example 38

[0136] Z-38, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 5-methoxyindole-3-carboxylic acid, while the rest is the same as in Example 1. The resulting solid, with the structure shown in Formula Z-38, has a yield of 68%, is a white solid, and has a melting point of 196.6-197.7 °C. 1H NMR (400MHz, DMSO-d6, ppm) δ11.45(s,1H),11.17(s,1H),8.99(s,1H),8.46(d,J=5.7Hz,1H),8.04(d,J=3.2Hz,1H),7.72(dd,J=8.1,2.3Hz,2H), 7.68(d,J=2.8Hz,1H),7.43-7.37(m,2H),7.32(dd,J=8.9,2.8Hz,1H),6.79(dd,J=8.8,2.8Hz,1H),4.51(d,J=5.8Hz,2H),3.76(d,J=2.6Hz,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.26,164.67,154.84,144.36,131.60,128.60,127 .47,127.36,112.97,112.64,110.45,103.00,55.67,42.12.HR-MS(ESI):calcd.C 18 H 17 N3O4,[M+H]+m / z:340.1297,found:340.1298.

[0137] Example 39

[0138] Z-39, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 5-bromoindole-3-carboxylic acid, while the rest is the same as in Example 1. The resulting product, having the structure shown in Formula Z-39, has a yield of 70%, is a white solid, and has a melting point of 191.6-192.5 °C. 1 HNMR (400MHz, DMSO-d6, ppm) δ11.80(s,1H),11.19(s,1H),9.01(s,1H),8.60(t,J=5.5Hz,1H),8.33(t,J=2.9Hz,1H),8. 15(d,J=3.2Hz,1H),7.74(dd,J=8.1,3.8Hz,2H),7.42(td,J=9.2,3.7Hz,3H),7.32-7.26(m,1H),4.53(t,J=4.9Hz,2H). 13C NMR(101MHz,DMSO-d6,ppm)δ164.66,144.07,135.32,131.65,129.68,128.47,127 .52,127.37,124.94,123.67,114.41,113.74,110.41,42.15.HR-MS(ESI):calcd.C 17 H 14 BrN3O3,[M+H]+m / z:388.0297,found:388.0299.

[0139] Example 40

[0140] Z-40, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 6-bromoindole-3-carboxylic acid, while the rest is the same as in Example 1. The resulting solid, with the structure shown in Formula Z-40, has a yield of 70%, is a white solid, and has a melting point of 195.4-196.3 °C. 1 HNMR(400MHz,DMSO-d6,ppm)δ11.70(s,1H),11.17(s,1H),9.00(s,1H),8.59(t,J=6.1Hz,1H),8.11(d,J=8.3Hz,2H) ,7.76-7.68(m,2H),7.65(d,J=1.7Hz,1H),7.41(d,J=8.0Hz,2H),7.25(dd,J=8.5,1.8Hz,1H),4.52(d,J=5.9Hz,2H). 13 C NMR (101MHz, DMSO-d6, ppm) δ164.69,144.08,137.48,131.64,129.20,127.61,127.52, 127.37,125.75,123.81,123.22,115.11,114.96,111.00,42.15.HR-MS(ESI):calcd.C 17 H 14 BrN3O3,[M+H]+m / z:388.0297,found:388.0299.

[0141] Example 41

[0142] Z-41, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 6-methoxyindole-3-carboxylic acid, while the rest is the same as in Example 1. The resulting product, having the structure shown in Formula Z-41, has a yield of 72%, is a white solid, and has a melting point of 170.8-171.2 °C. 1 HNMR (400MHz, DMSO-d6, ppm) δ11.39(d,J=2.9Hz,1H),11.20(s,1H),9.04(s,1H),8.49(t,J=6.1Hz,1H),8.00(d,J=8.7Hz,1H),7.94(d,J=2.8 Hz,1H),7.72(d,J=8.0Hz,2H),7.40(d,J=7.9Hz,2H),6.94(d,J=2.3Hz,1H),6.76(dd,J=8.7,2.3Hz,1H),4.50(d,J=5.9Hz,2H),3.77(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.20,164.72,156.32,144.30,137.39,131.55,127.50,12 7.34,127.08,122.04,120.73,111.05,110.84,95.18,55.63,42.12.HR-MS(ESI):calcd.C 18 H 17 N3O4,[M+H]+m / z:340.1297,found:340.1298.

[0143] Example 42

[0144] Z-42, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that the indole-3-carboxylic acid in step (1) is replaced with 2-methylindole-3-carboxylic acid, while the rest is the same as in Example 2. The yield of formula Z-42 is 38%, a white solid with a melting point of 185.4-186.5℃. 1H NMR (600MHz, DMSO-d6, ppm) δ11.16 (s, 1H), 8.98 (s, 1H), 8.25 (t, J = 6.0Hz, 1H),7.86-7.80(m,1H),7.72(d,J=8.2Hz,2H),7.49-7.46(m,1H),7.44(d,J =8.1Hz,2H),7.30(t,J=7.5Hz,2H),7.24(d,J=7.6Hz,1H),7.15-7.10(m,2 H),7.02(d,J=7.5Hz,2H),5.49(s,2H),4.54(d,J=5.9Hz,2H),2.58(s,3H). 13 CNMR(101MHz,DMSO-d6,ppm)δ165.73,140.52,138.10,136.30,129.79,129.16,127.73,127.58,127.3 5,126.69,125.80,121.93,120.88,120.10,110.55,109.09,46.17,42.77,12.02.HR-MS(ESI):calcd.C 13 H 13 N3O3,[M+H]+m / z:414.1817,found:414.1825.

[0145] Example 43

[0146] Z-43, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 1 in that the indole-3-carboxylic acid in step (1) is replaced with 2-methylindole-3-carboxylic acid, while the rest is the same as in Example 2. The resulting product, having the structure shown in Formula Z-43, has a yield of 50%, is a white solid, and has a melting point of 134.4-135.2 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.49(s,1H),11.17(s,1H),9.00(d,J=11.1Hz,1H),7.99(t,J=6.1Hz,1H),7.81(d,J=7.3Hz,1 H),7.72(d,J=7.9Hz,2H),7.43(d,J=7.8Hz,2H),7.36-7.30(m,1H),7.13-7.02(m,2H),4.53(d,J=6.0Hz,2H),2.60(s,3H). 13C NMR(101MHz,DMSO-d6,ppm)δ165.91,164.65,144.37,140.10,135.15,131.53,127.51,127 .32,126.49,121.49,120.38,119.90,111.40,107.95,42.57,13.82.HR-MS(ESI):calcd.C 18 H 17 N3O3,[M+H]+m / z:324.1348,found:324.1350.

[0147] Example 44

[0148] Z-44, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 2 in that indole-3-carboxylic acid in step (1) is replaced with 2-methylindole-3-carboxylic acid, and bromobenzene in step (2) is replaced with cyclopropylbenzyl bromide. The rest is the same as in Example 2. The obtained product has the structure shown in Formula Z-44 in 72% yield, is a white solid, and has a melting point of 125.4-126.7℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.17(s,1H),8.98(s,1H),8.18(d,J=6.2Hz,1H ),7.79(d,J=7.7Hz,1H),7.74(d,J=8.0Hz,2H),7.51(d,J=8.0Hz,1H),7.44( d,J=8.0Hz,2H),7.12(dt,J=18.6,7.1Hz,2H),4.54(d,J=5.9Hz,2H),4.11(d ,J=6.7Hz,2H),2.65(s,3H),1.16(td,J=8.0,4.0Hz,1H),0.52-0.31(m,4H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.86,164.63,144.25,140.19,136.12,131.56,127.54,127.36,12 5.70,121.63,120.59,119.91,110.55,108.65,46.61,42.67,12.06,11.78.HR-MS(ESI):calcd.C 22 H 23 N3O3,[M+H]+m / z:378.1817,found:378.1832.

[0149] Example 45

[0150] Z-45, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that in Example 2 in that indole-3-carboxylic acid in step (1) is replaced with 2-methylindole-3-carboxylic acid, and bromobenzene in step (2) is replaced with 4-fluorobenzyl bromide. Formula Z-45 has a yield of 56%, is a white solid, and has a melting point of 168.9-170.3℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.09 (s, 1H), 9.25-8.81 (m, 1H), 8.25 (t, J = 6.1Hz, 1H), 7.86-7.79 (m, 1H), 7.76-7.70 (m, 2H), 7.5 0-7.42(m,3H),7.14(ddd,J=8.9,6.9,2.1Hz,4H),7.07(dd,J=8.4,5.6Hz,2H),5.47(s,2H),4.54(d,J=5.9Hz,2H),2.59(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.68,163.01,160.60,144.15,140.40,136.18,134.30,134.27,131.61,129.80,128.80,128.72 ,127.60,127.36,125.82,121.99,120.93,120.12,116.07,115.86,110.52,109.20,45.47,42.69,12.00.HR-MS(ESI):calcd.C 25 H 22 FN3O3,[M+H]+m / z:432.1723,found:432.1726.

[0151] Example 46

[0152]

[0153] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using silica gel (100–200 mesh) and sample-graded using a (200–300 mesh) column. The intermediate was purified using a (petroleum ether / ethyl acetate) solution as the mobile phase; the yield was 93%, and the purity was 97%.

[0154] (2) Dissolve 1 mmol of the substance obtained in step (1) in DMF, add 3 mmol of potassium hydroxide and 2 mmol of benzyl bromide under stirring at 650 rpm at room temperature, and react for 3-4 h. After the reaction is complete as monitored by TLC, extract three times with ethyl acetate and water. Wash the upper organic phase with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir-fry the sample, pack into a column, and separate and purify with petroleum ether / ethyl acetate as the mobile phase to obtain the intermediate; the yield is 93% and the purity is 97%.

[0155] (3) Dissolve 1 mmol of the substance obtained in step (2) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C under reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain the intermediate. The yield is 95%, and the purity is 97%.

[0156] (4) Dissolve 1 mmol of the product from step (3) in DMF, add 1.2 mmol of EDCI and 0.5 mmol of DMAP as condensing agents, and stir at room temperature for 0.5 h. Then add 1.1 mmol of N-Boc-1,2-phenylenediamine and react at room temperature for 2-3 h. After the reaction is complete, extract the system three times with ethyl acetate and water, wash the upper layer with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir the sample, pack into a column, and separate and purify the intermediate by column chromatography. The yield was 62%, and the purity was 97%.

[0157] (5) Dissolve 1 mmol of the solution from step (4) in 1,4-dioxane, add 100 mmol of hydrochloric acid, and react for 2.5 h. A precipitate forms during the reaction. After the reaction is complete, evaporate the 1,4-dioxane solution to dryness under reduced pressure, dissolve the system in water, add saturated sodium bicarbonate solution under ice bath conditions to adjust the solution to a weakly alkaline state, let stand for 15 min, filter, and dry to obtain compound Z-46 with a yield of 67% and a purity of 98%. Compound Z-46 has a yield of 67%, is a white solid, and has a melting point of 210.3-211.1 °C. 1H NMR (400MHz, DMSO-d6, ppm) δ9.96 (s, 1H), 8.60 (d, J = 5.9Hz, 1H), 8.24-8.14 (m, 2H), 8.00 (d, J = 8.0Hz, 2H), 7.51 (dd, J = 21.8, 7.9Hz, 3H), 7.37-7. 23(m,6H),7.15(dq,J=20.0,7.2Hz,3H),7.04(d,J=7.9Hz,1H),6.91(t, J=7.5Hz,1H),5.47(s,2H),4.56(d,J=5.9Hz,2H),3.56(d,J=2.2Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ165.86,164.74,144.77,137.91,136.66,133.07,131.75,129.16,128.39,128.12,127.73 ,127.53,127.31,127.14,126.98,122.65,121.77,121.26,119.53,111.13,110.63,49.97,42.26.HR-MS(ESI):calcd.C 30 H 26 N4O2,[M+H]+m / z:475.2134,found:475.2137.

[0158] Example 47

[0159]

[0160] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The sample was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The sample was then stir-fried in silica gel (100–200 mesh), packed into a column (200–300 mesh), and purified using petroleum ether / ethyl acetate solution as the mobile phase to obtain the intermediate; the yield was 93%, and the purity was 97%.

[0161] (2) Dissolve 1 mmol of the substance obtained in step (1) in DMF, add 3 mmol of potassium hydroxide and 2 mmol of benzyl bromide under stirring at 650 rpm at room temperature, and react for 3-4 h. After the reaction is complete as monitored by TLC, extract three times with ethyl acetate and water. Wash the upper organic phase with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir-fry the sample, pack into a column, and separate and purify with petroleum ether / ethyl acetate as the mobile phase to obtain the intermediate; the yield is 93% and the purity is 97%.

[0162] (3) Dissolve 1 mmol of the substance obtained in step (2) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C under reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain compound Z-47. Compound Z-47 has a yield of 83%, is a white solid, and has a melting point of 284.6-285.4°C. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.61(t,J=6.0Hz,1H),8.23-8.14(m,2H),7.91(d,J=8.0Hz,2H),7.54(d,J=8.0Hz,1H), 7.45(d,J=7.7Hz,2H),7.37-7.30(m,2H),7.30-7.23(m,3H),7.21-7.10(m,2H),5.47(s,2H),4.54(d,J=5.8Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.85,164.79,145.87,137.85,136.63,131.74,129.98,129.84,129.16,128 .13,127.72,127.70,127.10,122.68,121.76,121.30,111.13,110.50,49.96,42.28.HR-MS(ESI):calcd.C 24 H2N2O3,[M+H]+m / z:385.1552,found:385.1559.

[0163] Example 48

[0164]

[0165] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using silica gel (100–200 mesh) and sample-graded using a (200–300 mesh) column. The intermediate was purified using a (petroleum ether / ethyl acetate) solution as the mobile phase; the yield was 93%, and the purity was 97%.

[0166] (2) Dissolve 1 mmol of the substance obtained in step (1) and 0.6 mmol of anhydrous potassium phosphate in toluene, add the solution while stirring at 650 rpm at room temperature, then add 1.2 mmol of bromobenzene, 0.3 mmol of catalyst CuI and 2.1 mmol of trans-(1R,2R)-N,N-dimethyl-1,2-cyclohexanediamine, and react in an oil bath at 110 °C for 4-5 h under nitrogen protection. After the reaction is completed, the system is extracted three times with ethyl acetate and water, the upper organic phase is washed with saturated NaCl solution, dried with anhydrous sodium sulfate, and the organic phase is evaporated to dryness. Silica gel is added to fry the sample, and the sample is packed into a column. Petroleum ether / ethyl acetate is used as the mobile phase for separation and purification to obtain an intermediate with a yield of 93% and a purity of 97%.

[0167] (3) Dissolve 1 mmol of the substance obtained in step (2) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C under reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain the intermediate. The yield is 95%, and the purity is 97%.

[0168] (4) Dissolve 1 mmol of the product from step (3) in DMF, add 1.2 mmol EDCI and 0.5 mmol DMAP as condensing agents, and stir at room temperature for 0.5 h. Then add 1.1 mmol N-Boc-1,2-phenylenediamine and react at room temperature for 2-3 h. After the reaction is complete, extract the system three times with ethyl acetate and water, wash the upper layer with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir the sample, pack into a column, and separate and purify the intermediate by column chromatography. The yield is 62% and the purity is 97%.

[0169] (5) Dissolve 1 mmol of the solution from step (4) in 1,4-dioxane, add 100 mmol of hydrochloric acid, and react for 2.5 h. A precipitate forms during the reaction. After the reaction is complete, evaporate the 1,4-dioxane solution to dryness under reduced pressure, dissolve the system in water, add saturated sodium bicarbonate solution under ice bath conditions to adjust the solution to a weakly alkaline state, let stand for 15 min, filter, and dry to obtain compound Z-48. Compound Z-48 has a yield of 56%, is a white solid, and has a melting point of 207.3-208.0 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ10.08 (s, 1H), 8.78 (d, J=6.4Hz, 1H), 8.46 (d, J= 2.3Hz,1H),8.35-8.26(m,1H),8.04(d,J=7.9Hz,2H),7.69-7.60(m,4H),7.5 8-7.46(m,4H),7.38(d,J=7.9Hz,1H),7.26(tt,J=7.1,5.4Hz,2H),7.15(dd, J=8.0,1.9Hz,2H),7.03-6.95(m,1H),4.60(d,J=5.9Hz,2H),3.57(s,2H).13C NMR(101MHz,DMSO-d6,ppm)δ165.90,164.56,144.64,138.81,136.07,133.01,131.19,130.49,128.46,127.89, 127.81,127.54,127.40,126.99,124.71,123.65,122.19,122.14,112.37,111.19,42.29.HR-MS(ESI):calcd.C 29 H 24 N4O2,[M+H]+m / z:461.1977,found:461.1983.

[0170] Example 49

[0171]

[0172] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using silica gel (100–200 mesh) and sample-graded using a (200–300 mesh) column. The intermediate was purified using a (petroleum ether / ethyl acetate) solution as the mobile phase; the yield was 93%, and the purity was 97%.

[0173] (2) Dissolve 1 mmol of the substance obtained in step (1) and 0.6 mmol of anhydrous potassium phosphate in toluene, add the solution while stirring at 650 rpm at room temperature, then add 1.2 mmol of bromobenzene, 0.3 mmol of catalyst CuI and 2.1 mmol of trans-(1R,2R)-N,N-dimethyl-1,2-cyclohexanediamine, and react in an oil bath at 110 °C for 4-5 h under nitrogen protection. After the reaction is completed, the system is extracted three times with ethyl acetate and water, the upper organic phase is washed with saturated NaCl solution, dried with anhydrous sodium sulfate, and the organic phase is evaporated to dryness. Silica gel is added to fry the sample, and the sample is packed into a column. Petroleum ether / ethyl acetate is used as the mobile phase for separation and purification to obtain an intermediate with a yield of 93% and a purity of 97%.

[0174] (3) Dissolve 1 mmol of the substance obtained in step (2) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C under reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain compound Z-49. The compound with the structure shown in formula Z-49 has a yield of 72%, is a white solid, and has a melting point of 257.3-258.2°C. 1 H NMR (400MHz, DMSO-d6, ppm) δ8.72(d,J=6.2Hz,1H),8.41(s,1H),8.29(d,J=7.3Hz,1H),7.92(d,J=7.8Hz,2H),7 .64(d,J=4.5Hz,4H),7.55(d,J=7.7Hz,1H),7.47(t,J=7.4Hz,3H),7.26(p,J=7.2Hz,2H),4.58(d,J=5.8Hz,2H). 13C NMR (101MHz, DMSO-d6, ppm) δ167.74,164.54,145.80,138.80,136.07,131.13,130.48,129.88,129.81, 127.90,127.79,127.75,124.71,123.66,122.19,122.14,112.32,111.18,42.31.HR-MS(ESI):calcd.C 23 H 18 N2O3,[M+H]+m / z:371.1395,found:371.1398.

[0175] Example 50

[0176]

[0177] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using (200-300 mesh) silica gel and purified using petroleum ether / ethyl acetate as the mobile phase to obtain the intermediate; the yield was 93%, and the purity was 97%.

[0178] (2) Dissolve 1 mmol of the substance obtained in step (1) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C under reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain the intermediate. The yield is 95%, and the purity is 97%.

[0179] (3) Dissolve 1 mmol of the product from step (2) in DMF, add 1.2 mmol EDCI and 0.5 mmol DMAP as condensing agents, and stir at room temperature for 0.5 h. Then add 1.1 mmol N-Boc-1,2-phenylenediamine and react at room temperature for 2-3 h. After the reaction is complete, extract the system three times with ethyl acetate and water, wash the upper layer with saturated NaCl solution, dry with anhydrous sodium sulfate, evaporate the organic phase to dryness, add silica gel to stir the sample, pack into a column, and separate and purify the intermediate by column chromatography. The yield is 62% and the purity is 97%.

[0180] (4) Dissolve 1 mmol of the product from step (3) in 1,4-dioxane, add 100 mmol of hydrochloric acid, and react for 2.5 h. A precipitate forms during the reaction. After the reaction is complete, evaporate the 1,4-dioxane solution to dryness under reduced pressure, dissolve the system in water, add saturated sodium bicarbonate solution under ice bath conditions to adjust the solution to a weakly alkaline state, let stand for 15 min, filter, and dry to obtain compound Z-48. Compound Z-50 has a yield of 72%, is a white solid, and has a melting point of 201.3-202.2 °C. 1 H NMR(400MHz,DMSO-d6,ppm)δ11.58(d,J=3.0Hz,1H),9.63(s,1H),8.53(t,J=6 .1Hz,1H),8.16(d,J=7.7Hz,1H),8.09(d,J=2.9Hz,1H),7.95(d,J=7.9Hz,2H) ,7.45(dd,J=11.1,8.0Hz,3H),7.20-7.05(m,3H),6.97(td,J=7.6,1.5Hz,1H) ,6.81-6.75(m,1H),6.61(t,J=7.6Hz,1H),4.98(s,2H),4.56(d,J=6.0Hz,2H). 13 C NMR (101MHz, DMSO-d6, ppm) δ165.69,165.14,144.62,143.30,136.63,133.44,128.35,128.27,127.40,127.15, 126.93,126.63,124.01,122.37,121.48,120.86,116.97,116.76,112.31,110.87,42.18.HR-MS(ESI):calcd.C 23 H 20 N4O2,[M+H]+m / z:385.1664,found:385.1672.

[0181] Example 51

[0182]

[0183] (1) 1 mmol of indole-3-carboxylic acid and 1.1 mmol of methyl 4-aminomethylbenzoate were placed in a 250 mL round-bottom flask and dissolved in dichloromethane. While stirring at room temperature, 2 mmol of EDCI and 0.2 mmol of HOBT were added sequentially, followed by 1.1 mmol of triethylamine. The mixture was incubated at room temperature for 4 h, and monitored by thin-layer chromatography. The mixture was extracted three times with dichloromethane and water. The lower organic phase was washed with saturated NaCl solution, dried over anhydrous sodium sulfate, and the dichloromethane was evaporated. The mixture was then packed into a column using (200-300 mesh) silica gel and purified using petroleum ether / ethyl acetate as the mobile phase to obtain the intermediate; the yield was 93%, and the purity was 97%.

[0184] (2) Dissolve 1 mmol of the substance obtained in step (1) in methanol solution, add 2-3 mL of water, and add 10 mmol of sodium hydroxide solution while stirring at 650 rpm at room temperature. After dissolving at room temperature, place the mixture in an oil bath at 60°C and reflux for 4-5 h. After the reaction is complete as monitored by TLC, evaporate the methanol to remove it, add water to dissolve the mixture, and then place it in an ice bath. Adjust the pH to 3-4 with concentrated hydrochloric acid. Finally, allow it to stand, filter, and dry to obtain Z-51. The yield of compound Z-51 is 85%, a white solid, with a melting point of 237.8-238.5°C. 1 HNMR (400MHz, DMSO-d6, ppm) δ12.85 (s, 1H), 11.59 (s, 1H), 8.53 (d, J = 6.1Hz, 1H), 8.23-8.06 (m,2H),7.95-7.89(m,2H),7.45(t,J=7.7Hz,3H),7.19-7.07(m,2H),4.56(d,J=5.9Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.74,165.14,146.20,136.62,129.85,129.66,128.38, 127.63,126.62,122.38,121.48,120.86,112.30,110.79,42.19.HR-MS(ESI):calcd.C 17 H 14 N2O3,[M+H]+m / z:295.1082,found:295.1087.

[0185] Example 52

[0186] Z-52, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 50 in that indole-3-carboxylic acid in step (1) is replaced with 6-methylindole-3-carboxylic acid. Compound Z-52 has a yield of 73%, is a white solid, and has a melting point of 223.7-224.6 °C. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.45 (s, 1H), 9.69 (d, J = 3.9 Hz, 1H), 8.50 (d, J = 5. 7Hz, 1H), 8.02 (q, J=4.0, 3.3Hz, 2H), 7.96 (dd, J=8.3, 3.1Hz, 2H), 7.46 (dd, J=8. 4,3.1Hz,2H),7.25-7.15(m,2H),7.03-6.89(m,2H),6.83(dd,J=8.1,3.5Hz,1H ),6.69-6.60(m,1H),5.34(s,2H),4.55(d,J=6.1Hz,2H),2.39(d,J=2.9Hz,3H). 13 CNMR(101MHz,DMSO-d6,ppm)δ165.72,165.19,144.71,142.47,137.07,133.36,131.44,128.27,127.78,127.42,12 7.16,126.91,124.51,124.45,122.61,121.15,117.56,117.17,112.04,110.78,42.17,21.77.HR-MS(ESI):calcd.C 24 H 22 N4O2,[M+H]+m / z:399.1821,found:399.1826.

[0187] Example 53

[0188] Z-53, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 51 in that the indole-3-carboxylic acid in step (1) is replaced with 6-methylindole-3-carboxylic acid, while the rest is the same as in Example 51. The obtained product has a yield of 78% and is a white solid with a melting point of 227.8-228.7 °C, having the structure shown in Formula Z-53. 1HNMR(400MHz,DMSO-d6,ppm)δ11.43(s,1H),8.45(d,J=6.1Hz,1H),8.05-7.95(m,2H),7.94-7.87(m,2H ),7.43(d,J=8.0Hz,2H),7.21(s,1H),6.93(dd,J=8.2,1.5Hz,1H),4.53(d,J=5.9Hz,2H),2.39(s,3H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.93,165.16,145.88,137.05,131.44,129.79,127.76 ,127.54,124.50,122.60,121.15,112.02,110.72,42.18,21.76.HR-MS(ESI):calcd.C 18 H 16 N2O3,[M+H]+m / z:309.1239,found:309.1244.

[0189] Example 54

[0190] Z-54, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 50 in that indole-3-carboxylic acid in step (1) is replaced with 6-bromoindole-3-carboxylic acid, while the rest is the same as in Example 50. The compound of formula Z-54 has a yield of 77%, is a white solid, and has a melting point of 231.2-232.1℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.43(s,1H),9.67(d,J=3.9Hz,1H),8.50(d,J=5.7Hz,1H),8.01(q,J=4.0,3.3Hz,2H),7.94(dd,J=8.3,3.1Hz,2H),7. 43(dd,J=8.4,3.1Hz,2H),7.25-7.14(m,2H),7.03-6.89(m,2H),6.82(dd, J=8.1,3.5Hz,1H),6.69-6.60(m,1H),5.35(s,2H),4.57(d,J=6.1Hz,2H). 13C NMR (101MHz, DMSO-d6, ppm) δ165.72,165.19,144.71,142.47,137.07,133.36,131.44,128.27,127.78,127.42, 127.16,126.91,124.51,124.45,122.61,121.15,117.56,117.17,112.04,110.78,42.17.HR-MS(ESI):calcd.C 23 H 19 BrN4O2,[M+H]+m / z:463.0769,found:463.0772.

[0191] Example 55

[0192] Z-55, a novel indole-based small molecule inhibitor of HDAC6, has the following structural formula: The preparation process differs from that of Example 51 in that the indole-3-carboxylic acid in step (1) is replaced with 6-bromoindole-3-carboxylic acid. Formula Z-55 has a yield of 70%, is a white solid, and has a melting point of 230.2-231.1℃. 1 H NMR (400MHz, DMSO-d6, ppm) δ11.43 (s, 1H), 8.45 (d, J = 6.1Hz, 1H), 8.05-7.95 (m, 2H), 7.94-7.87 (m,2H),7.43(d,J=8.0Hz,2H),7.21(s,1H),6.93(dd,J=8.2,1.5Hz,1H),4.53(d,J=5.9Hz,2H). 13 C NMR(101MHz,DMSO-d6,ppm)δ167.93,165.16,145.88,137.05,131.44,129.79,127 .76,127.54,124.50,122.60,121.15,112.02,110.72,42.18.HR-MS(ESI):calcd.C 17 H 13 BrN2O3,[M+H]+m / z:373.0188,found:373.0189.

[0193] Experimental Example 1

[0194] Compounds with structures shown in formulas Z-1 to Z-55 were subjected to in vitro enzyme activity assays as follows: Utilizing the deacetylation property of HDAC6, recombinant HDAC6 protein was first incubated with a polypeptide containing acetylated lysine and an AMC fluorescent group at 37°C for 20 min to expose the AMC fluorescent group. Trypsin was then added to hydrolyze the polypeptide, releasing the fluorescent group. Using a microplate reader, the change in fluorescence intensity was measured at an excitation wavelength of 355 nm and an emission wavelength of 460 nm to evaluate the inhibition rate of the target compound. Vorinostat (SAHA) was used as a positive control. Based on a set concentration gradient, the fluorescence intensity after treatment with the compound at different concentrations was measured, and the inhibition rate was calculated. The HDAC1 assay was performed similarly. The IC50 of the compounds was calculated using GraphPad Prism 8.0 software. 50 Inhibition rate = (positive control fluorescence intensity - compound fluorescence intensity) / (positive control fluorescence intensity - blank group fluorescence intensity) × 100%. The results of the inhibition activity test are shown in Table 1.

[0195] Table 1. Selective inhibitory activity of the compounds of the present invention for HDAC6.

[0196]

[0197]

[0198] Using SAHA as a positive control, compounds with an inhibition rate of over 60% against HDAC6 were selected, and their IC50 for HDAC6 was determined. 50 The values ​​and experimental results are shown in Table 2.

[0199] Table 2 shows the IC performance of some compounds of this invention on HDAC6. 50 value

[0200]

[0201]

[0202] As shown in Tables 1 and 2, the novel indole-based HDAC6 small molecule inhibitor provided by this invention exhibits good selective inhibition of HDAC6 compared to the positive control SAHA.

[0203] Experimental Example 2

[0204] Compound Z-7, which exhibits highly efficient and selective inhibition of HDAC6, was selected, and its inhibitory effect on the proliferation of human gastric cancer cells MGC-803 was tested using the MTT assay. Specifically, the cells were cultured in a high-glucose medium containing 10% fetal bovine serum at 37°C in a 5% CO2 incubator. MGC-803 cells were seeded at a density of 2500 cells / well in 96-well plates and cultured for 12 hours. After cell attachment, a 100 μM stock solution of the test compound was prepared into gradient concentrations, and 200 μL was added to each well. After incubation for 48 or 72 hours, 20 μL of 5 mg / mL MTT solution was added to each well, and the plates were cultured for another 5 hours. The supernatant was then discarded, and 150 μL of DMSO solution was added to each well. The plates were shaken at low speed for 15 minutes to fully dissolve the formazan crystals. Blank and negative control wells were also included, and the absorbance of each well was measured at 490 nm using an enzyme-linked immunosorbent assay (ELISA) reader. The inhibition rate was calculated and fitted using GraphPad Prism 8.0 software to obtain the IC. 50 Value. Inhibition rate (%) = 1 - (OD-treated group - OD blank group) / (OD negative control group - OD blank group) × 100%. The experimental results are shown in Table 3.

[0205] Table 3 Comparison of proliferation inhibition between compound Z-7 of the present invention and SAHA

[0206] compound <![CDATA[MGC-803IC 50 (μM)]]> Z-7 2.30±0.36 SAHA 6.02±0.79

[0207] The results in Table 3 show that the novel indole-based HDAC6 small molecule inhibitor Z-7 of the present invention has a good inhibitory effect on the proliferation of MGC-803 cells, and its inhibitory effect on the proliferation of MGC-803 cells is significantly better than that of the positive control SAHA.

[0208] In summary, the novel indole-based HDAC6 small molecule inhibitor provided by this invention effectively inhibits the proliferative activity of gastric cancer cells by chelating with metal ions within the cells to form stable complexes. Experimental results show that, compared to the positive control SAHA, the novel indole-based HDAC6 small molecule inhibitor provided by this invention not only exhibits superior selective inhibition of HDAC6 but also inhibits gastric cancer cell proliferation in a concentration-dependent manner, demonstrating promising application prospects in the preparation of HDAC6-targeted inhibitors and drugs for inhibiting the proliferative activity of gastric cancer cells.

Claims

1. An indole-based HDAC6 small molecule inhibitor, characterized in that, A compound represented by Formula I or a pharmaceutically acceptable salt thereof; In formula I, R1is H; R2is selected from one of the group consisting of 2. A process for the preparation of an indole-based HDAC6 small molecule inhibitor as claimed in claim 1, characterized by, The technical route of the preparation method is shown as follows: The preparation method of the indole HDAC6 small molecule inhibitor comprises the following steps: ① a condensation reaction of raw material A, raw material B, condensing agent a and alkaline substance a in solvent a to obtain intermediate C; ② a reaction of intermediate C, alkaline substance c and raw material a in solvent d to obtain intermediate E; the raw material a is a bromide compound; ③ a reaction of intermediate E and hydroxylamine aqueous solution in solvent b, and then a reaction of alkaline substance b, and then adding acid substance and water after the reaction is completed, and then filtering to obtain the indole HDAC6 small molecule inhibitor represented by compound F.

3. The method for preparing the indole-based HDAC6 small molecule inhibitor according to claim 2, characterized in that, The solvent a is dichloromethane, the solvent b is a mixed solution of dichloromethane and methanol, and the solvent d is N,N-dimethylformamide.

4. The method for preparing the indole-based HDAC6 small molecule inhibitor according to claim 2, characterized in that, The alkaline substance a is triethylamine, the alkaline substance b is sodium hydroxide, and the alkaline substance c is potassium hydroxide; the acid substance is hydrochloric acid.

5. The method for preparing the indole-based HDAC6 small molecule inhibitor according to claim 2, characterized in that, The condensing agent a is EDCI or HOBt.

6. Use of an indole HDAC6 small molecule inhibitor according to claim 1, wherein the inhibitor is a compound of formula (I) ###0002### (I) or a pharmaceutically acceptable salt thereof. In the preparation of a drug for targeted treatment of cancer based on the HDAC6 target; the cancer is gastric cancer.

7. The use of an indole HDAC6 small molecule inhibitor according to claim 6, wherein the use is for the treatment of a disease or condition selected from the group consisting of: cancer, neurodegenerative diseases, inflammatory diseases, cardiovascular diseases, metabolic diseases, viral infections, and autoimmune diseases. The drug is a drug for inhibiting the proliferation activity of gastric cancer cells; the gastric cancer cells are MGC-803.

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