Selenium-containing compound as well as preparation method and application thereof

Abstract

The invention discloses a selenium-containing compound as well as a preparation method and application thereof. The structural general formula of the selenium-containing compound is shown as any one of formulas (I), (II), (III), (IV), (V) and (VI): # imgabs 0, wherein R1 is # imgabs 1 #, R8 is # imgabs 2 #, and R9 is one of H, F, Cl, Br and substituted or unsubstituted C1-C5 alkyl. In consideration of the special property of selenium and the effect of selenium in an isostere, a PD-1 / PD-L1 inhibitor of a selenium-containing small molecule targeted PD-L1 protein is designed and synthesized, the biological activity of the inhibitor is investigated, and experiments prove that the compound can remarkably inhibit interaction of PD-1 and PD-L1 at the molecular level, so that the compound can be used for preparing a medicine for preventing and treating the PD-1 and the PD-L1, and can be used for preparing a medicine for preventing and treating the PD-1 and the PD-L1. Therefore, the compound can be used for treating diseases related to interaction of PD-1 / PD-L1.

Description

Technical Field

[0001] The present invention relates to a selenium-containing compound and a preparation method and application thereof, and in particular to a selenium-containing PD-L1 small molecule inhibitor, a preparation method thereof and the use of the compound in treating diseases related to the PD-1 / PD-L1 signaling pathway, such as cancer, infectious diseases and autoimmune diseases. Background Art

[0002] Cancer has become a serious public health problem in China and one of the most common causes of death in China. According to the China Cancer Data Report, about 4.06 million people are diagnosed with cancer and about 2.41 million people die from cancer each year. Among male patients, lung cancer is the most common, accounting for 24.6%, followed by liver cancer, stomach cancer, rectal cancer and esophageal cancer; while among female patients, breast cancer is the most common, accounting for 16.72%, followed by lung cancer, rectal cancer, thyroid cancer and stomach cancer. Lung cancer is also the most common cause of death among all cancer patients.

[0003] Currently, cancer treatments include surgery, radiotherapy, chemotherapy, and targeted therapy, but as the treatment time increases, drug resistance and recurrence are more likely to occur. Tumor immunotherapy, as a new type of therapy that has developed rapidly in recent years, regulates the body's immune system rather than directly attacking tumor cells to enhance the body's natural immune defense against tumors and eliminate tumor cells to treat cancer. Immunotherapy is considered the third revolution after traditional treatment and targeted therapy.

[0004] Immune checkpoint inhibition therapy (ICT) is one of the immunotherapy methods. It uses the immune checkpoints (IC) in the human body to regulate the signaling pathways of the immune system, maintain autoimmune tolerance and regulate immune responses. In cancer patients, tumor cells suppress the immune activity of T cells by overexpressing immunosuppressive molecules such as PD-L1, thereby escaping immune attacks. ICT aims to restore the killing effect of T cells on tumors by blocking these inhibitory signals, thereby achieving the purpose of treating tumors.

[0005] At present, the clinical application of PD-1 / PD-L1 immunosuppressants is mainly monoclonal antibodies (mAbs). Although mAbs have achieved certain success in clinical practice, they have limitations, such as immune tolerance imbalance, pharmacokinetic differences, and structural instability. Although small molecule inhibitors have been developed for nearly 10 years and have not yet been launched on the market, the results of clinical trials have shown that small molecule PD-1 / PD-L1 inhibitors have better bioavailability and tissue penetration, and may become another important option for cancer treatment in the future.

[0006] In addition, selenium, as a key trace element, is essential for human health. Selenium plays an important role by participating in various physiological processes, such as scavenging free radicals and regulating the activity of thyroid hormones. Selenium supplementation can have a positive impact on human health directly or indirectly. Considering the special properties of selenium and its role in electronic isosteres, the present invention designed and synthesized PD-1 / PD-L1 inhibitors containing selenium small molecules targeting PD-L1 protein, and investigated their biological activities. Summary of the invention

[0007] The technical problem solved by the present invention is to provide a selenium-containing small molecule compound that inhibits the PD-1 / PD-L1 interaction, a preparation method thereof, and use thereof in preparing drugs for preventing or treating diseases related to the PD-1 / PD-L1 signaling pathway.

[0008] Provided are selenium-containing compounds represented by the following general formulae (I), (II), (III), (IV), (V), and (VI) and pharmaceutically acceptable salts thereof.

[0009]

[0010] in:

[0011] R1 is Where R8 is R9 is one of the following: H, F, Cl, Br, substituted or unsubstituted C1-C5 alkyl;

[0012] R2 is C1-C6 alkyl, C3-C6 cycloalkyl, Ar-CH2- or 5-12 membered heterocyclic group; wherein Ar is a substituted or unsubstituted C6-C10 aromatic ring, or a 5-12 membered heteroaromatic ring, wherein the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, C1-C4 alkyl, (C1-C4) alkoxy, hydroxy, amino, cyano, trifluoromethyl, difluoromethyl, (C1-C4) alkylsulfonyl, (C1-C4) alkylsulfinyl, (C1-C4) alkylsulfonylamino, aminosulfonyl, (C1-C5) acylamino;

[0013] R3 and R5 are each independently selected from: hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C3-C8 cycloalkyl or R3 and R5 together with the nitrogen atom to which they are attached form a 4-6 membered heterocyclic ring; the alkyl or alkoxy may be optionally substituted by one or more X groups; X is selected from: hydrogen, halogen, hydroxy, carboxyl, methylthio, amino, furanyl, dimethylamino, hydroxy-substituted isopropylamino or -NHCOR 12 or-CONR 13 R 14 ; where R 12Selected from C1-C4 alkyl; the heterocyclic ring may be carboxyl or -CONR 13 R 14 Substitution; wherein R 13 and R 14 Each independently selected from: hydrogen, C1-C6 alkyl, C1-C6 alkoxy or R 13 and R 14 Together with the nitrogen atom to which they are attached, they form a 5-6 membered heterocyclic ring; wherein the alkyl, alkoxy or heterocyclic ring may be optionally substituted by one or more Y groups; wherein Y is selected from: hydrogen, halogen, hydroxyl, carboxyl, amino or acetamido;

[0014] R4 is H, F, Cl, Br, substituted or unsubstituted C1-C5 alkyl;

[0015] R6 is a C1-C6 chain carboxyl group, or

[0016] R7 is

[0017] R 10 for

[0018] R 11 is a substituted or unsubstituted C1-C5 alkyl group.

[0019] The pharmaceutically acceptable salts of the compounds of the general formula (1), (II), (III), (IV), (V), and (VI) can be synthesized by general chemical methods.

[0020] Generally, the salts can be prepared by reacting the free base or acid with an equal chemical equivalent or excess of an acid (inorganic or organic acid) or a base (inorganic or organic base) in a suitable solvent or solvent combination.

[0021] Preferably, in the structures of the general formula (1), (II), (III), (IV), (V), and (VI):

[0022] R2 is Ar-CH2-, or a 5-6 membered heterocyclic group; wherein Ar is a substituted or unsubstituted C6 aromatic ring, or a 5-6 membered heteroaromatic ring, wherein the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, amino, cyano, trifluoromethyl, difluoromethyl, (C1-C4) alkylsulfonyl, (C1-C4) alkylsulfinyl, (C1-C4) alkylsulfonylamino, aminosulfonyl, (C1-C5) acylamino;

[0023] R3 and R5 are each independently selected from: hydrogen, C1-C8 alkyl or R3 and R5 together with the nitrogen atom to which they are attached form a 4-6 membered heterocyclic ring; the alkyl group may be optionally substituted by one or more X groups; X is selected from: hydrogen, halogen, hydroxyl, carboxyl, methylthio, amino, furanyl, dimethylamino, hydroxy-substituted isopropylamino or -NHCOR 12 or -CONR 13 R 14 ; where R 12 Selected from C1-C4 alkyl; the heterocyclic ring may be carboxyl or -CONR 13 R 14 Substitution; wherein R 13 and R 14 Each independently selected from: hydrogen, C1-C6 alkyl, C1-C6 alkoxy or R 13 and R 14 Together with the nitrogen atom to which they are attached, they form a 5-6 membered heterocyclic ring; wherein the alkyl, alkoxy or heterocyclic ring may be optionally substituted by one or more Y groups; wherein Y is selected from: hydrogen, halogen, hydroxyl, carboxyl, amino or acetamido;

[0024] R4 is H or Cl.

[0025] More specifically, the compound of the general formula (1), (II), (III), (IV), (V), (VI) is any of the following compounds:

[0026]

[0027]

[0028] Another object of the present invention is to provide a method for preparing the compounds represented by the general formula (1), (II), (III), (IV), (V), and (VI).

[0029] The preparation method of the compound represented by general formula (I) is as follows:

[0030]

[0031] Compound 39 is used as a raw material, and intermediate 42 is obtained through nitro reduction, diazotization and substitution. Intermediate 42 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (I), wherein R2, R3, R4, R5, R8 and R9 are as defined above.

[0032] The pharmaceutically acceptable salts of the compounds of the general formula (I) can be synthesized by general chemical methods.

[0033] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0034] The preparation method of the compound represented by general formula (II) is as follows:

[0035]

[0036] Compound 43 is used as a raw material, and intermediate 50 is obtained through selenoic acid hydrolysis, cyclization, dehydration, reduction, and substitution. Intermediate 50 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (II), wherein R2, R3, R4, R5, R8, and R9 are as defined above.

[0037] The pharmaceutically acceptable salts of the compounds of the general formula (II) can be synthesized by general chemical methods.

[0038] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0039] The preparation method of the compound represented by general formula (III) is as follows:

[0040]

[0041] Compound 51 is used as a raw material, and intermediate compound 56 or 57 is prepared through selenization reaction, substitution reaction, and demethylation reaction. Compound 56 or 57 is hydrolyzed or amine compound HNR3R5 is reductively aminized to obtain a compound of formula (III), wherein R3, R5, R6, R7, R8, and R9 are as defined above.

[0042] The pharmaceutically acceptable salts of the compounds of the general formula (III) can be synthesized by general chemical methods.

[0043] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0044] The preparation method of the compound represented by general formula (IV) is as follows:

[0045]

[0046] Compound 58 is used as a raw material, and intermediate compound 63 is obtained through Suzuki reaction, reduction reaction, and substitution reaction. Compound 63 and amine compound HNR3R5 are subjected to reductive amination to obtain a compound of formula (IV). 10 The definition of is as mentioned above.

[0047] The pharmaceutically acceptable salts of the compounds of the general formula (IV) can be synthesized by general chemical methods.

[0048] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0049] The preparation method of the compound represented by general formula (V) is as follows:

[0050]

[0051] Compound 64 is used as a raw material, and intermediate compound 70 is obtained through Miyaura borylation reaction, Suzuki reaction, reduction reaction, and substitution reaction. Compound 70 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (V). 11 The definition of is as mentioned above.

[0052] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0053] The preparation method of the compound represented by general formula (VI) is as follows:

[0054]

[0055] Compound 71 is used as a raw material, and a substitution reaction is performed to obtain an intermediate compound 72, and compound 72 is subjected to reductive amination with an amine compound HNR3R5 to obtain a compound of formula (VI), wherein R2, R3, R4, R5, and R8 are as defined above.

[0056] Generally, the salts can be prepared by reacting a free base or acid with an equal chemical equivalent or excess amount of an acid (inorganic acid or organic acid) or a base (inorganic base or organic base) in a suitable solvent or composition.

[0057] The beneficial effects achieved by the present invention are as follows: Taking into account the special properties of selenium and its role in electronic isosteres, the present invention designs and synthesizes PD-1 / PD-L1 inhibitors containing selenium small molecules targeting PD-L1 protein, and examines their biological activities. Experimental verification shows that the compounds of the present invention can significantly inhibit the interaction between PD-1 and PD-L1 at the molecular level, and therefore can be used to treat diseases related to the interaction between PD-1 / PD-L1. DETAILED DESCRIPTION

[0058] The technical solution of the present invention is further described below in conjunction with embodiments.

[0059] Reagents and Materials: All reagents required for the experiments were of commercially available chemical or analytical grade unless otherwise specified.

[0060] Instruments: Bruker AV-400 and Bruker AV-600 NMR spectrometers were used for NMR spectroscopy. ZAD-2F and VG300 mass spectrometers were used for mass spectrometry. HPLC purity determination method: The purity of the compound was determined by HPLC (high performance liquid chromatography) analysis, and its purity was confirmed to be above 96%. C18 column (InertSustain C18, 4.6×250mm, 5μm) and Shimadzu LC-20A were used for HPLC analysis, and UV detection was performed at 254nm.

[0061] Example 1: Synthesis of N-{[4-({[2-chloro-3-(2-fluorophenyl)phenyl]methyl}seleno)-2-{[(3-cyanophenyl)methyl]oxy}phenyl]methyl}-L-serine (1)

[0062]

[0063] (1) Synthesis of 2-chloro-1-(2-fluorophenyl)-3-methylbenzene (1B)

[0064] 2-Chloro-3-bromotoluene (1A) (24.30 mmol, 1.0 eq), o-fluorophenylboric acid (26.80 mmol, 1.1 eq), K2CO3 (60.80 mmol, 2.5 eq), 1,4-dioxane 50 mL, and water 20 mL were added to a 250 mL round-bottom flask, and the mixture was stirred at room temperature for 30 min under nitrogen protection. Tetrakis(triphenylphosphine)palladium (730.00 μmol, 0.03 eq) was added, and the mixture was reacted at 80 °C for 8 h under N2 protection. The reaction was completed after TLC monitoring, and the solid residue was filtered by adding diatomaceous earth. 1,4-dioxane was distilled off under reduced pressure, the aqueous phase was extracted with EA 3 times, the organic phases were combined, the organic phases were washed with water and saturated brine in sequence, the organic phase was dried over anhydrous sodium sulfate to remove water, and 1B was distilled off under reduced pressure to obtain 5.3 g of an oily substance, which was directly used for the next step reaction.

[0065] (2) Synthesis of 3-(bromomethyl)-2-chloro-1-(2-fluorophenyl)benzene (1C)

[0066] 1B (5.3 g, 24.00 mmol, 1 eq) and 60 mL of acetonitrile were added to a 250 mL round-bottom flask. NBS (26.40 mmol, 1.1 eq) was added first under stirring, and then BPO (2.40 mmol, 0.1 eq) was added. The temperature was slowly raised to 80°C and the reaction was continued for 12 h. The reaction was completed after monitoring by TLC. The acetonitrile was distilled under reduced pressure, and impurities were washed with EA and water for 3 times. The organic phases were combined, washed once with saturated brine, dried over anhydrous sodium sulfate to remove water, and distilled under reduced pressure to obtain 7.0 g of crude oily 1C. Purification was performed by silica gel column with PE as the mobile phase to obtain 6.9 g of white solid with a yield of 95.90%. 1 H NMR (400MHz, Chloroform-d) δ7.75 (ddd, J=8.6, 5.0, 1.3Hz, 1H), 7.55 (ddd, J=8. 0,2.0,1.4Hz,1H),7.46–7.30(m,4H),7.27(dq,J=7.6,1.1Hz,1H),4.59(s,2H).

[0067] (3) Synthesis of 3-{[(2-formyl-5-nitrophenyl)oxy]methyl}benzene-1-carbonitrile (2B)

[0068] 2-Hydroxy-4-nitrobenzaldehyde (2A) (29.90mmol, 1eq), K2CO3 (32.90mmol, 1.1eq), 3-bromomethylbenzonitrile (32.90mmol, 1.1eq) and 50mL of DMF solvent were added to a 100mL round-bottom flask, and the mixture was reacted at 55°C for 4h. After the reaction was completed by TLC, 10 times the amount of water was added for elution, stirred for 10min, and filtered to obtain a white solid. 8.4g of crude 2B was obtained by drying and directly used for the next step.

[0069] (4) Synthesis of 3-{[(5-amino-2-formylphenyl)oxy]methyl}benzene-1-carbonitrile (2C)

[0070] Iron powder (148.80mmol, 5.0eq) was added to a 250mL round-bottom flask, followed by 20mL water and 1mL glacial acetic acid. The mixture was stirred for 10min under nitrogen protection. 2B (8.4g, 29.80mmol, 1.0eq) was dissolved (slightly soluble) in 20mL acetic acid and 100mL EA and then added dropwise to the round-bottom flask. The reaction was carried out under nitrogen protection at room temperature. The reaction solution changed from turbid to clear. After 8h of reaction, the reaction was monitored by TLC. The iron powder was filtered, the reaction solution was adjusted to neutral pH with saturated sodium bicarbonate, extracted with EA three times, the organic phases were combined and washed with water and saturated brine in turn, the organic phases were dried over anhydrous sodium sulfate to remove water, and the red solid 2C crude product 7.5g was obtained by vacuum distillation, which was directly put into the next step of reaction.

[0071] (5) Synthesis of (3-{[(3-cyanophenyl)methyl]oxy}-4-formylphenyl)selenocarbonitrile (2E)

[0072] 2C (29.70mmol, 1.0eq) was added to a 250mL round-bottom flask, and 10% hydrochloric acid (65mL, 6.0eq) was added. Stirring was carried out at 0°C. Sodium nitrite (32.70mmol, 1.1eq) was dissolved in 30mL water and slowly added to the reaction bottle using a constant pressure dropping funnel. After the addition was completed, stirring was continued for 2h at zero degree. The pH of the reaction solution was adjusted to 5-6 with saturated sodium acetate. Potassium selenocyanate (44.60mmol, 1.5eq) was dissolved in 20mL water and quickly added to the reaction solution. Stirring was carried out at room temperature for 30min. The reaction solution was extracted with EA 3 times, and the organic phase was washed with water and saturated brine in turn. The organic phase was dried with anhydrous sodium sulfate to remove water, and the crude oil was distilled under reduced pressure to obtain 6.8g. Purification was performed on a silica gel column, and the mobile phase PE:EA4:1 (volume ratio) was used to remove the above impurities. The product was washed out with DCM to obtain 5.5g of 2E yellow solid, with a yield of 54.21%. 1 H NMR (400MHz, Chloroform-d) δ10.43 (s, 1H), 7.91 (d, J = 7.5Hz, 1H), 7.61–7.58 (m, 2H), 7.57–7. 55(m,1H),7.55–7.53(m,1H),7.51–7.46(m,1H),7.33(d,J=2.2Hz,1H),5.16(d,J=0.8Hz,2H).

[0073] (6) Synthesis of 3-({[5-({[2-chloro-3-(2-fluorophenyl)phenyl]methyl}seleno)-2-formylphenyl]oxy}methyl)benzene-1-carbonitrile (1D)

[0074] NaH (258.0 mg, purity 60%, 6.45 mmol, 2.2 eq) was added to a 50 mL three-necked flask, nitrogen protection was applied, 5 mL of anhydrous DMF was added, compound 2E (1.0 g, 2.93 mmol, 1.0 eq) and compound 1C (1.1 g, 3.52 mmol, 1.2 eq) were dissolved in 20 mL of anhydrous DMF and added to the three-necked flask, and the mixture was reacted at 70 °C for 30 min. The reaction was monitored by TLC. After the reaction, 1 mL of water was used to quench the unreacted NaH in the reaction solution, the reaction solution was washed with saturated sodium bicarbonate, extracted with EA twice, the organic phases were combined, washed once with water and saturated brine respectively, dried over anhydrous sodium sulfate, and distilled under reduced pressure to obtain a crude black charred product, which was passed through a silica gel column with a mobile phase of PE:EA 10:1 (volume ratio) to obtain 1D as a yellow powdery solid 420 mg with a yield of 26.79%. 1H NMR(400MHz,Chloroform-d)δ10.43(s,1H),7.83(d,J=7.8Hz,1H),7.75(ddd,J=8.5,5.2 ,1.3Hz,1H),7.62–7.58(m,2H),7.56–7.52(m,2H),7.51–7.46(m,1H),7.42–7.38(m,2H), 7.36(d,J=1.7Hz,1H),7.36–7.33(m,1H),7.31(d,J=6.8Hz,1H),7.30–7.28(m,1H),7.19( d, J=2.2Hz, 1H), 5.16 (s, 2H), 3.78 (dd, J=13.2, 0.8Hz, 1H), 2.93 (dd, J=13.1, 0.8Hz, 1H).

[0075] (7) Synthesis of N-{[4-({[2-chloro-3-(2-fluorophenyl)phenyl]methyl}seleno)-2-{[(3-cyanophenyl)methyl]oxy}phenyl]methyl}-L-serine (1)

[0076] In a 10 mL round-bottom flask, intermediate 1D (50.0 mg, 93.50 μm, 1.0 eq), L-serine (19.6 mg, 187.00 μm, 2.0 eq), 1 mL each of DMF and MeOH solvents were added, and two drops of glacial acetic acid were added. After stirring at 25 ° C for 30 min, sodium cyanoborohydride (17.6 mg, 280.00 μm, 3.0 eq) was added. Stirring was continued at 25 ° C, and the reaction was monitored by TLC until the reaction was completed. Methanol solvent was distilled under reduced pressure, and compound 1 was purified by post-treatment: 7.7 mg, yield 12.96%, off-white solid. 1 H NMR(400MHz,Chloroform-d)δ7.99(dd,J=21.0,8.3Hz,1H),7.79–7.58(m,3H),7 .54–7.46(m,1H),7.42(dd,J=10.8,4.8Hz,1H),7.39–7.34(m,1H),7.33–7.27(m, 2H),7.24(d,J=1.8Hz,1H),7.20(m,1H),7.13(m,1H),6.68–6.55(m,1H),6.55–6. 47(m,1H),5.23(s,2H),5.10(s,2H),4.12(s,2H),3.43(Brs,2H),3.08(Brs,1H). MS (ESI) m / z 625.08031 [m+H] + .

[0077] Example 2: Synthesis of 3-{[(2-hydroxyethyl)amino]methyl}-5-{[(2-methyl-3-phenylphenyl)methyl]selenoyl}phenyl)oxy]methyl}benzene-1-carbonitrile (6)

[0078]

[0079] (1) Synthesis of 2-methyl-3-phenylbenzene-1-carboxaldehyde (6B)

[0080] 2-Methyl-3-bromobenzaldehyde (5.02mmol, 1.0eq), phenylboronic acid (5.53mmol, 1.1eq), potassium carbonate (12.60mmol, 2.5eq), 15mL of 1,4-dioxane and 6mL of water were added to a 50mL round-bottom flask, stirred at room temperature for 30min under nitrogen protection, and tetrakis(triphenylphosphine)palladium catalyst (151.00μmol, 0.03eq) was added. Nitrogen protection was applied and the reaction was carried out under oil bath conditions of 80°C for 8h. The reaction was monitored by TLC spot plate. After the reaction was completed, the catalyst solid residue was removed by diatomaceous earth filtration, and the organic solvent was removed by vacuum distillation. The remaining aqueous phase was extracted twice with EA, and the organic phases were combined. The organic phases were washed with water and saturated brine in turn, and the organic phase was dehydrated with anhydrous sodium sulfate. The organic phase was vacuum distilled to obtain 1.0g of granular yellow-white (6B) crude product. It was directly put into the next step reaction.

[0081] (2) Synthesis of (2-methyl-3-phenylphenyl)methanol (6C)

[0082] The crude product 6B (980.0 mg, 4.99 mmol, 1.0 eq) and 20 mL of methanol were added to a 50 mL round-bottom flask, stirred for 10 min in an ice bath, and sodium borohydride (4.99 mmol, 1.0 eq) was slowly added. The reaction was carried out in an ice bath for 10 min. The reaction was monitored by TLC. After the reaction was completed, 1 mL of water was added dropwise to quench the reaction solution. The reaction solution was distilled under reduced pressure to remove the methanol solvent. The remaining residue was dissolved with EA, washed once with water and saturated brine respectively, and the organic phase was dried over anhydrous sodium sulfate to remove water. 6C crude oil was obtained by distillation under reduced pressure 1.1 g. It was directly used for the next step reaction.

[0083] (3) Synthesis of 1-bromomethyl-2-methyl-3-phenylbenzene (6D)

[0084] 6C (962.0 mg, 4.85 mmol, 1.0 eq), triphenylphosphine (5.09 mmol, 1.05 eq) and 20 mL of DCM were added to a 50 mL round-bottom flask, and NBS (5.09 mmol, 1.05 eq) was slowly added under stirring. The reaction was allowed to react for 10 h at room temperature and monitored by TLC. After the reaction, silica gel was passed through a column with a mobile phase of PE:EA=40:1 (volume ratio) to obtain 1.1 g of white solid intermediate 6D with a purity of 99.65% and a yield of 83.36%. 1 H NMR (400MHz, Chloroform-d) δ7.46–7.41(m,2H),7.41–7.37(m,2H),7.37–7.33(m,3H),7.23(dq,J=7.6,1.2Hz,1H),4.55(s,2H),2.28(s,3H).

[0085] (4) Synthesis of 3-[(2-formyl-5-{[(2-methyl-3-phenylphenyl)methyl]seleno}phenyl)methyl]benzene-1-carbonitrile (6E)

[0086] Referring to the method of Example 1, 1-bromomethyl-2-methyl-3-phenylbenzene (6D) was reacted with (3-{[(3-cyanophenyl)methyl]oxy}-4-formylphenyl)selenocarbonitrile (2E) to obtain a yellow-green oil with a purity of 99.83% and a yield of 24.42%. 1 HNMR(400MHz,Chloroform-d)δ10.43(s,1H),7.83(d,J=7.8Hz,1H),7.63–7.58(m,2H),7 .56–7.52(m,1H),7.51–7.48(m,1H),7.46–7.42(m,2H),7.41–7.39(m,1H),7.38–7.37(m, 1H),7.36(d,J=1.1Hz,1H),7.35–7.34(m,1H),7.33(d,J=1.4Hz,1H),7.33–7.28(m,1H),7 .19(d,J=2.2Hz,1H),7.15(dq,J=7.3,0.9Hz,1H),5.16(s,2H),3.88(s,2H),2.20(s,3H).

[0087] (5) Synthesis of 3-{[(2-hydroxyethyl)amino]methyl}-5-{[(2-methyl-3-phenylphenyl)methyl]seleno}phenyl)oxy]methyl}benzene-1-carbonitrile (6)

[0088] Referring to the method of Example 1, 3-[(2-formyl-5-{[(2-methyl-3-phenylphenyl)methyl]selenoyl}phenyl)methyl]benzene-1-carbonitrile (6E) was reacted with 2-aminoethanol to obtain a light brown viscous oil, namely compound 6. Yield: 20.25%, HPLC: 98.35%. 1 H NMR(400MHz,Chloroform-d)δ7.73(s,1H),7.67(d,J=7.8Hz,1H),7.62(d,J=7.6Hz,1H),7. 51(t,J=7.7Hz,1H),7.40(t,J=7.2Hz,2H),7.37–7.32(m,1H),7.30–7.27(m,2H),7.25–7.23 (m,1H),7.15(d,J=7.7Hz,1H),7.12(s,1H),7.11(d,J=2.3Hz,1H),7.06–7.03(m,1H),6.93 (s,1H),5.08(s,2H),4.17(s,2H),4.09(s,2H),3.73(Brs,2H),2.95(Brs,2H),2.22(s,3H). MS(ESI)m / z 543.15453[m+H] + .

[0089] Example 3: Synthesis of N-({[2-(3-cyanobenzyloxy)]-4-{[2-(2-fluorophenyl)-1H-1,3-selenoxazol-4-yl]methoxy}}benzyl-L-proline (14)

[0090]

[0091] (1) Synthesis of o-fluorobenzyl selenamide (14B)

[0092] 2-Fluorobenzonitrile 14A (72.70 mmol, 1.0 eq) was added to a 250 mL round-bottom flask, followed by 100 mL of ethanol solvent and phosphorus pentaselenide (13.3 g, 29.10 mmol, 0.4 eq). (Phosphorus pentaselenide was prepared in-house, 5.0 eq of selenium was melted in a reaction bottle by an alcohol lamp, 3.0 eq of red phosphorus was slowly added, stirred with a glass rod for 10 min, and cooled to obtain phosphorus pentaselenide), the temperature was raised to boiling point, water (10.5 g, 581.00 mmol, 8.0 eq) was added dropwise, and a spherical condenser tube mouth was covered with a 2-layer balloon to prevent the generated hydrogen selenide gas from overflowing. The mixture was stirred for 5 h, saturated sodium bicarbonate was added to the reaction solution to adjust the pH, the residue was filtered, and ethanol in the reaction solution was removed by vacuum distillation. The remaining aqueous phase was extracted twice with EA, and the organic phase was extracted once with water and saturated sodium chloride in turn. The organic phase was dehydrated with anhydrous sodium sulfate and vacuum distilled to obtain 13.2 g of crude product 14B, which was directly used for the next step reaction.

[0093] (2) Synthesis of ethyl 2-(2-fluorophenyl)-1H-1,3-selenoxazole-4-carboxylate (14D)

[0094] 14B (13.2 g, 60.40 mmol, 1.0 eq) was added to a 250 mL round-bottom flask, and 100 mL of acetonitrile solvent was added, and the mixture was stirred at room temperature. Ethyl 3-bromopyruvate (17.7 g, 90.60 mmol, 1.5 eq) was dissolved in 50 mL of acetonitrile solvent and slowly added dropwise to the reaction solution using a constant pressure dropping funnel. After the addition was completed, the reaction was continued for 1 h. The reaction was monitored by TLC. When the reaction was complete, the acetonitrile was spin-dried and post-treated to obtain 17.8 g of a crude oily product of 14C. 14C (17.8 g, 53.50 mmol, 1.0 eq) was added to a 500 mL round-bottom flask, 200 mL of acetonitrile solvent was added, p-toluenesulfonic acid (4.6 g, 26.80 mmol, 0.5 eq) was added, and the mixture was refluxed at 80°C for 20 min. The reaction was monitored by TLC. After the reaction was completed, the pH was adjusted to neutral with saturated sodium bicarbonate, and the black solid produced by the reaction was removed by filtration. ACN was removed by vacuum distillation, and the mixture was extracted twice with EA. The organic phase was washed with water and saturated brine in sequence, dried over anhydrous sodium sulfate to remove water, and the organic phase was vacuum distilled to obtain 12.8 g of a crude oily product. The product was filtered through a silica gel column with the mobile phase PE:EA=10:1 (volume ratio) to obtain 10.4 g of 14D as a white solid with a yield of 61.8%. 1 HNMR(400MHz,Chloroform-d)δ8.95(s,1H),7.75(ddd,J=7.9,5.0,1.5Hz,1H),7. 51–7.45(m,1H),7.39–7.30(m,2H),4.35(q,J=7.1Hz,2H),1.19(t,J=7.1Hz,3H). MS(ESI)m / z 321.97530[m+Na] + .

[0095] (3) Synthesis of [2-(2-fluorophenyl)-1H-1,3-selenoxazol-4-yl]methanol (14E)

[0096] Lithium aluminum tetrahydride (33.10 mmol, 1.0 eq) was added to a 250 mL three-necked flask under nitrogen protection. 10 mL of anhydrous THF was added, 14D was dissolved in 100 mL of anhydrous THF, and 14D (10.4 g, 33.10 mmol, 1.0 eq) solution was added dropwise to the three-necked flask under ice bath conditions under nitrogen protection. The reaction was continued at room temperature for 12 h. The reaction was monitored by TLC. After the reaction was completed, 1.3 mL of water was added dropwise under ice bath conditions, stirred for 5 min, 1.30 mL of 15% sodium hydroxide was added dropwise and continued to stir for 5 min, diatomaceous earth was added to filter the residue, the filter cake was washed with EA, the filtrate was distilled under reduced pressure, the residue was dissolved with EA, the organic phase was washed with water and saturated brine once in sequence, the organic phase was dried over anhydrous sodium sulfate to remove water, and 14E was distilled under reduced pressure to obtain 7.3 g of a brick-red solid crude product with a crude product yield of 81.0%. 1 H NMR (600MHz, Chloroform-d) δ 8.31–8.20 (m, 1H), 7.91 (s, 1H), 7.45–7.35 (m, 1H), 7.25–7.21 (m, 1H), 7.19 (t, J = 9.8Hz, 1H), 4.83 (s, 2H).

[0097] (4) Synthesis of 4-(bromomethyl)-2-(2-fluoromethyl)-1H-1,3-selenoxazole (14F)

[0098] 14E (7.3 g, 26.80 mmol, 1.0 eq), triphenylphosphine (40.20 mmol, 1.5 eq), 200 mL of acetonitrile solvent were added to a 500 mL round-bottom flask, and carbon tetrabromide (40.20 mmol, 1.5 eq) was slowly added under stirring. The mixture was stirred at room temperature for 24 h, and the reaction was monitored by TLC. After the reaction was completed, the mixture was filtered and the filtrate was distilled under reduced pressure to obtain a crude oily solid. The mixture was filtered through a silica gel column with a mobile phase of PE:EA=10:1 (volume ratio) to obtain 8.8 g of 14F as a white solid with a yield of 98.0%. 1 H NMR(400MHz,Chloroform-d)δ8.67(s,1H),7.74(ddd,J=7.9,5.0,1.5Hz,1H),7 .51–7.45(m,1H),7.35(td,J=8.0,1.5Hz,1H),7.33–7.28(m,1H),4.44(s,2H).

[0099] (5) Synthesis of 4-{[2-(2-fluoromethyl)-1H-1,3-selenoxazol-4-yl]methoxy}-2-hydroxybenzaldehyde (14G)

[0100] 14F (8.8 g, 26.20 mmol, 1.0 eq), 2,4-dihydroxybenzaldehyde (28.90 mmol, 1.1 eq), K2CO3 (28.90 mmol, 1.1 eq), DMF 100 mL were added to a 250 mL round-bottom flask, and the mixture was reacted at 55 °C for 4 h. The reaction was monitored by TLC. After the reaction, 10 times the volume of water was added, stirred for 20 min, filtered, and the filter cake was dried in an oven at 50 °C to obtain 9.0 g of yellow-white 14G crude product. The mixture was filtered through a silica gel column with a mobile phase of PE:EA=20:1 (volume ratio) to obtain 4.50 g of 14G as a white solid with a yield of 43.7%. 1 H NMR(600MHz,Chloroform-d)δ11.46(s,1H),9.73(s,1H),8.34–8.28(m,1H),8.08(s,1H),7.46(d,J=8.7Hz,1H),7.45–7.4 0(m,1H),7.28–7.24(m,1H),7.21(dd,J=11.1,8.6Hz,1H),6.67(dd,J=8.6,2.2Hz,1H),6.60(d,J=2.0Hz,1H),5.33(s,2H).

[0101] (6) Synthesis of (4-{[2-(2-fluorophenyl)-1H-1,3-selenoxazole]methoxy}-2-[(3-cyanophenyl)benzyloxy])benzaldehyde (14H)

[0102] 14G (1.0 g, 2.60 mmol, 1.0 eq), K2CO3 (2.80 mmol), 3-bromomethylbenzonitrile (2.80 mmol, 1.1 eq) and 10 mL of DMF were added to a 25 mL round-bottom flask and reacted at 55 °C for 4 h. The reaction was monitored by TLC. After the reaction was completed, 5 eq of water was added and the mixture was extracted with EA three times. The organic phases were combined and washed with water and saturated brine in sequence. The organic phase was dried over anhydrous sodium sulfate to remove water and distilled under reduced pressure to obtain 1.4 g of a crude brown solid of 14H. The crude product was slurried with 10 mL of a solvent (PE:EA=10:1 (volume ratio)) for 30 min. The product was filtered and dried to obtain 1.2 g of a light brown solid of 14H with a yield of 92.8%, and the next step was directly performed.

[0103] (7) Synthesis of N-{4-{[2-(2-fluorophenyl)-1H-1,3-selenoxazole]methoxy}-2-[(3-cyanophenyl)benzyloxy]}benzyl-L-proline (14)

[0104] In a 10 mL round-bottom flask, intermediate 14H (100.0 mg, 203.00 μm, 1.0 eq), L-proline (46.9 mg, 407.00 μm, 2.0 eq), 2 mL of DMF and MeOH solvents were added, and two drops of glacial acetic acid were added. After stirring at 25 ° C for 30 min, sodium triacetoxyborohydride (129.0 mg, 610.00 μm, 3.0 eq) was added. Stirring was continued at 25 ° C, and the reaction was monitored by TLC until the reaction was completed. The methanol solvent was distilled under reduced pressure, and the compound 14 was purified by post-treatment: 15.63 mg, yield: 12.81%, off-white solid. HPLC: 98.53%. 1 H NMR(400MHz,Chloroform-d)δ8.28(td,J=7.7,1.5Hz,1H),8.04(s,1H),7.73(d,J=7.8Hz,1H),7.68(s,1H ),7.61(d,J=7.7Hz,1H),7.51(t,J=7.7Hz,1H),7.47–7.37(m,1H),7.28(d,J=9.0Hz,1H),7.23(d,J=6.8Hz ,1H),7.19(dd,J=10.3,1.9Hz,1H),6.61(d,J=6.9Hz,2H),5.22(s,2H),5.17(s,2H),4.23–4.13(m,2H),3. 81(dd,J=9.2,4.1Hz,1H),3.55–3.47(m,1H),2.87(q,J=8.6Hz,1H),2.38–2.16(m,2H),1.98–1.88(m,2H). MS(ESI)m / z 592.11453[m+H] +

[0105] Example 4: Synthesis of [(2-{[2-methyl-(1,1′-biphenyl)]-3-yl}-3-oxo-2,3-dihydrobenzo[1,2-d]isoselenazol-5-yl)oxy]acetic acid (22)

[0106]

[0107] (1) Synthesis of 6,6′-bis(3-methoxybenzoic acid)selenide (22B)

[0108] Selenium powder (60.80 mmol, 1.0 eq), 85% hydrazine hydrate (3.6 g, 60.80 mmol, 1.0 eq), and 61 mL (3.4 g, 60.80 mmol, 1.0 eq) of 1 mol / L potassium hydroxide aqueous solution were added to a 500 mL round-bottom flask, and the mixture was reacted at 70 °C for 1 h under nitrogen protection to prepare a potassium selenide aqueous solution, which was then placed at room temperature for later use.

[0109] A 250mL round-bottom flask was added with raw material 22A (59.80mmol, 1.0eq) and 120mL (4.4g, 120.00mmol, 2.0eq) of 1mol / L hydrochloric acid aqueous solution. The mixture was stirred for 10min in an ice-salt bath. Sodium nitrite (4.9g, 71.80mmol, 1.2eq) was prepared into a 1mol / L solution and slowly added dropwise to the reaction solution using a constant pressure dropping funnel. After the addition was completed, the reaction was continued for 1h. After the reaction was completed, the reaction solution was added dropwise to an aqueous potassium selenide solution, the temperature was raised to 70°C, and the reaction was continued for 2h. After the reaction was completed, the pH was adjusted to <1 using a 10% hydrochloric acid aqueous solution to produce a precipitate. The precipitate was filtered to obtain a crude brown solid.

[0110] Recrystallization: In a 250 mL round-bottom flask, dissolve the brown solid with 100 mL 1 mol / L NaCO3 aqueous solution, boil at 100°C for 1 h, filter the reaction solution residue while hot, adjust the filtrate to pH <1 with 10% hydrochloric acid aqueous solution to produce a precipitate, filter the precipitate, and dry the filter cake to obtain 8.7 g of 22B brown solid with a yield of 65.19%. Directly proceed to the next step.

[0111] (2) Synthesis of 5-methoxy-2-[2-methyl-(1,1′-biphenyl)-3-yl]benzo[1,2-d]isoselenazol-3(2H)-one (22D)

[0112] 5 g 22B, 40 mL thionyl chloride and 2 drops of DMF were added to a 250 mL round-bottom flask. The mixture was refluxed for 4 h. The thionyl chloride was evaporated under reduced pressure to dryness to obtain a black oily crude product 22C. The flask was sealed for later use.

[0113] 2-Methyl-3-phenylaniline (43.30mmol, 2.0eq) was dissolved in 50mL DCM solution, triethylamine (65.17mmol, 3.0eq) was added, 22C was dissolved in 100mL DCM, and slowly added dropwise to the stirred reaction solution using a constant pressure dropping funnel, reacted at room temperature for 24h, and the solvent was spin-dried by vacuum distillation, the solid was dissolved with EA, the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine in turn, and the organic phase was dried with anhydrous sodium sulfate to remove water, and a black tarry crude product was obtained. The silica gel column was passed through the column, and the mobile phase PE:EA=10:1 (volume ratio) washed out the raw material, and PE:EA=1:1 (volume ratio) washed out the product, and 22D was obtained as a light yellow solid 4.3g, with a yield of 50.19%. 1H NMR(400MHz,Chloroform-d)δ7.77(d,J=8.5Hz,1H),7.65(dd,J=7.9,1.2Hz,1H),7.46– 7.41(m,3H),7.40–7.32(m,5H),6.85(dd,J=8.6,1.9Hz,1H),3.81(s,3H),2.29(s,3H).

[0114] (3) Synthesis of 5-hydroxy-2-[2-methyl-(1,1′-biphenyl)-3-yl]benzo[1,2-d]isoselenazol-3-(2H)-one (22E)

[0115] 22D (4.3 g, 10.90 mmol, 1.0 eq) and 50 mL of anhydrous DCM were added to a 250 mL round-bottom flask. The reaction solution was stirred in a dry ice ethanol bath for 10 min. When the temperature dropped to about -70 ° C, 22.0 mL of 1 mol / L DCM solution of boron tribromide (5.5 g, 21.8 mmol, 2.0 eq) was slowly added dropwise. After the addition was completed, the reaction was stirred for 1 h under nitrogen protection and then continued to stir at room temperature for about 8 h. The reaction was monitored by TLC and the reaction was completed. 10 mL of methanol was added dropwise in a dry ice ethanol bath to quench the reaction. After quenching, the reaction was stirred at room temperature for 1 h, and the reaction was evaporated under reduced pressure. The solid was dissolved in DCM, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine in sequence. The organic phase was dried over anhydrous sodium sulfate to remove water, and the organic phase was evaporated under reduced pressure to obtain 22E as a burnt black solid. The residue was passed through a silica gel column with the mobile phase PE:EA=10:1–1:1 (volume ratio) to obtain 1.1 g of 22E as a dark brown solid with a yield of 27.01%. 1 HNMR(400MHz,Chloroform-d)δ7.78(d,J=8.9Hz,1H),7.65(dd,J=7.9,1.2Hz,1H),7.46–7.41(m,3H), 7.40–7.37(m,1H),7.37–7.33(m,3H),7.27(d,J=1.9Hz,1H),6.79(dd,J=8.9,2.1Hz,1H),2.29(s,3H).

[0116] (4) Synthesis of methyl (2-[2-methyl-(1,1′-biphenyl)-3-yl]-3-oxo-2,3-dihydrobenzo[1,2-d]isoselenazol-5-yl}oxy)acetate (22F)

[0117] 22E (100.0 mg, 262.90 μmol, 1.0 eq), σ-bromoacetic acid methyl ester (44.2 mg, 289.00 μmol, 1.1 eq), Cs2CO3 (289.00 μmol, 1.1 eq), and DMF 1 mL were added to a 10 mL Schlenk reaction tube, and the mixture was reacted at 50°C for 4 h. The reaction was monitored by TLC. After the reaction, 5 volumes of water were added, and the mixture was extracted with EA for 3 times. The organic phases were combined, washed with water and saturated brine in turn, and dried with anhydrous sodium sulfate to obtain 110.0 mg of crude 22F. The mixture was directly subjected to the next step of reaction.

[0118] (5) Synthesis of ({2-[2-methyl-(1,1′-biphenyl)-3-yl]-3-oxo-2,3-dihydrobenzo[1,2-d]isoselenazol-5-yl}oxy)acetic acid (22)

[0119] 22F (110.0 mg, 243.00 μmol, 1.0 eq) and lithium hydroxide (29.1 mg, 1.22 mmol, 5.0 eq) were added to a 10 mL round-bottom flask, and 1 mL of THF and 1 mL of H2O were added. The mixture was stirred at room temperature for 30 min, and the reaction was monitored by TLC. After the reaction was complete, THF was removed by vacuum distillation, and the aqueous phase was extracted with EA three times. The organic phases were combined, and the organic phases were washed with water and saturated brine in sequence. The organic phase was dried over anhydrous sodium sulfate to remove water, and the crude solid was distilled under reduced pressure. The compound 226.0 mg was purified to obtain brown powder, with a yield of 5.63%, and HPLC: 97.53%. 1 HNMR (400MHz, DMSO-d6) δ8.01(d,J=8.0Hz,1H),7.47(t,J=7.3Hz,3H),7.41–7.32(m,4H),7.32–7.18(m,4H),4.54(s,2H),1.99(d,J=22.0Hz,3H). MS(ESI)m / z 438.02500[mH] - .

[0120] Example 5: Synthesis of (23)

[0121]

[0122] (1) Synthesis of 3-[({2-[2-methyl-(1,1′-biphenyl)-3-yl]-3-oxo-2,3-dihydrobenzo[1,2-d]isoselenazol-5-yl}oxy)methyl]benzaldehyde (23A)

[0123] 22D (100.0 mg, 263.00 μm, 1.0 eq), m-bromomethylbenzaldehyde (289.00 μm, 1.1 eq), potassium carbonate (289.00 μm, 1.1 eq) were added to a 10 mL round-bottom flask. 2 mL of DMF was added and the mixture was reacted at 55 °C for 4 h. The reaction was monitored by TLC. After the reaction was completed, post-treatment was performed to obtain 130.0 mg of a crude oily product 23A. The intermediate was directly used for the next step reaction.

[0124] (2) Synthesis of {3-[({2-[2-methyl-(1,1′-biphenyl)-3-yl]-3-oxo-2,3-dihydrobenzo[1,2-d]isoselenazol-5-yl}oxy)methyl]benzyl}-L-proline (23)

[0125] A 10 mL round-bottom flask was charged with 23A (130.0 mg, 261.00 μm, 1.0 eq), L-proline (60.1 mg, 522.00 μm, 2.0 eq), 1 mL of methanol, 1 mL of DMF, a drop of acetic acid, and stirred at room temperature for 30 min. Sodium cyanoborohydride (49.2 mg, 782.00 μm1, 3.0 eq) was added and stirred at room temperature for 24 h. The reaction was monitored by TLC. After the reaction was completed, post-treatment was performed and purified to obtain 12.4 mg of compound 23. 1 HNMR(400MHz,Chloroform-d)δ7.82(d,J=8.6Hz,1H),7.65(dd,J=7.9,1.2Hz,1H),7.46–7.41(m,4 H),7.41–7.37(m,2H),7.37–7.33(m,3H),7.29–7.27(m,1H),7.28–7.23(m,1H),7.23–7.19(m,1H), 6.88(dd,J=8.5,2.7Hz,1H),5.10(s,2H),3.82–3.64(m,2H),3.51(dd,J=5.4,3.7Hz,1H),3.19–2.9 1(m,1H),2.83–2.68(m,1H),2.29(s,3H),2.05–1.93(m,1H),1.86–1.80(m,1H),1.80–1.65(m,2H). MS(ESI)m / z 597.12980[mH] - .

[0126] Evaluation of pharmacological activity of compounds

[0127] Biological test HTRF method to detect the activity of compounds inhibiting PD-1 / PD-L1 protein interaction

[0128] The in vitro protein level detection method uses the PD-1 / PD-L1 binding assay kit developed by Cisbio.

[0129] Screening principles and methods for PD-1 / PD-L1 small molecule inhibitors

[0130] Principle: PD-1 protein carries a HIS tag, and PD-1's ligand PD-L1 carries an hFc tag. Eu-labeled anti-hFc antibody and XL665-labeled anti-HIS antibody are respectively bound to the two label proteins. After laser excitation, energy can be transferred from the donor Eu to the acceptor XL665, causing XL665 to emit light. After adding inhibitors (compounds or antibodies), the binding of PD-1 and PD-L1 is blocked, making Eu and XL 665 far apart, energy cannot be transferred, and XL 665 will not emit light.

[0131] Experimental method: For specific methods, please refer to Cisbio's PD-1 / PD-L1 kit, which is briefly described as follows: 384-well white ELISA plate, add 4μL PD-1 protein and 4μL PD-L1 protein to each well, then add 2μL diluent or target compound diluted with diluent to each well, incubate at room temperature for 15 minutes, then add 10μL of anti-Tag 1-Eu3+ and anti-Tag2-XL665 mixture to each well, incubate at room temperature for 1h-4h, and then use a multifunctional ELISA reader to detect the fluorescence signal at 665nm and 620nm. HTRF rate = (665nm / 620nm)*10 4 8-10 concentrations of each compound were tested and IC was calculated using Graphpad software 50 .

[0132] The activity test results of the compounds are shown in Table 1.

[0133] Table 1. HTRF test results of compounds synthesized in the examples

[0134] Serial number Compound <![CDATA[HTRFIC 50 (μM)]]> 1 1 >1 2 2 0.5-1 3 3 >1 4 4 0.24 5 5 >1 6 6 1-1.5 7 7 1-1.5 8 8 1-1.5 9 9 1-1.5 10 10 0.65 11 11 >1 12 12 1-1.5 13 13 >1 14 14 >1 15 15 0.11 16 16 >1 17 17 >1 18 18 >1 19 19 0.069 20 20 >1 21 21 >1 22 22 >1 23 23 >1

[0135] Experimental conclusion: As can be seen from Table 1, the compounds of the present invention can significantly inhibit the interaction between PD-1 and PD-L1 at the molecular level, and can therefore be used to treat diseases related to the interaction between PD-1 / PD-L1.

Claims

1. A selenium-containing compound and a pharmaceutically acceptable salt thereof, characterized in that The general structural formula of the selenium-containing compound is shown in any one of formulas (I), (II), (III), (IV), (V), and (VI): in: R1 is Where R8 is R9 is one of the following: H, F, Cl, Br, substituted or unsubstituted C1-C5 alkyl; R2 is C1-C6 alkyl, C3-C6 cycloalkyl, Ar-CH2- or 5-12 membered heterocyclic group; wherein Ar is a substituted or unsubstituted C6-C10 aromatic ring, or a 5-12 membered heteroaromatic ring, wherein the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, C1-C4 alkyl, (C1-C4) alkoxy, hydroxy, amino, cyano, trifluoromethyl, difluoromethyl, (C1-C4) alkylsulfonyl, (C1-C4) alkylsulfinyl, (C1-C4) alkylsulfonylamino, aminosulfonyl, (C1-C5) acylamino; R3 and R5 are each independently selected from: hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C3-C8 cycloalkyl or R3 and R5 together with the nitrogen atom to which they are attached form a 4-6 membered heterocyclic ring; the alkyl or alkoxy may be optionally substituted by one or more X groups; X is selected from: hydrogen, halogen, hydroxy, carboxyl, methylthio, amino, furanyl, dimethylamino, hydroxy-substituted isopropylamino or -NHCOR 12 or-CONR 13 R 14 ; where R 12 Selected from C1-C4 alkyl; the heterocyclic ring may be carboxyl or -CONR 13 R 14 Substitution; wherein R 13 and R 14 Each independently selected from: hydrogen, C1-C6 alkyl, C1-C6 alkoxy or R 13 and R 14 Together with the nitrogen atom to which they are attached, they form a 5-6 membered heterocyclic ring; wherein the alkyl, alkoxy or heterocyclic ring may be optionally substituted by one or more Y groups; wherein Y is selected from: hydrogen, halogen, hydroxyl, carboxyl, amino or acetamido; R4 is one of the following: H, F, Cl, Br, substituted or unsubstituted C1-C5 alkyl; R6 is a C1-C6 chain carboxyl group, or R7 is R 10 for R 11 is a substituted or unsubstituted C1-C5 alkyl group.

2. The selenium-containing compound and the pharmaceutically acceptable salt thereof according to claim 1, characterized in that: R2 is Ar-CH2-, or a 5-6 membered heterocyclic group; wherein Ar is a substituted or unsubstituted C6 aromatic ring, or a 5-6 membered heteroaromatic ring, wherein the substitution refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, amino, cyano, trifluoromethyl, difluoromethyl, (C1-C4) alkylsulfonyl, (C1-C4) alkylsulfinyl, (C1-C4) alkylsulfonylamino, aminosulfonyl, (C1-C5) acylamino; R3 and R5 are each independently selected from: hydrogen, C1-C8 alkyl or R3 and R5 together with the nitrogen atom to which they are attached form a 4-6 membered heterocyclic ring; the alkyl group may be optionally substituted by one or more X groups; X is selected from: hydrogen, halogen, hydroxyl, carboxyl, methylthio, amino, furanyl, dimethylamino, hydroxy-substituted isopropylamino or -NHCOR 12 or -CONR 13 R 14 ; where R 12 Selected from C1-C4 alkyl; the heterocyclic ring may be carboxyl or -CONR 13 R 14 Substitution; wherein R 13 and R 14 Each independently selected from: hydrogen, C1-C6 alkyl, C1-C6 alkoxy or R 13 and R 14 Together with the nitrogen atom to which they are attached, they form a 5-6 membered heterocyclic ring; wherein the alkyl, alkoxy or heterocyclic ring may be optionally substituted by one or more Y groups; wherein Y is selected from: hydrogen, halogen, hydroxyl, carboxyl, amino or acetamido; R4 is H or Cl.

3. The selenium-containing compound and the pharmaceutically acceptable salt thereof according to claim 1, characterized in that: The compound is selected from any of the following compounds:

4. A method for preparing the selenium-containing compound according to claim 1, characterized in that The preparation method is as follows: Compound 39 is used as a raw material, and intermediate 42 is obtained through nitro reduction, diazotization, and substitution. Intermediate 42 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (I); wherein R2, R3, R4, R5, R8, and R9 are defined as in claim 1; Compound 43 is used as a raw material, and intermediate 50 is obtained through selenoic acid hydrolysis, cyclization, dehydration, reduction, and substitution. Intermediate 50 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (II); wherein R2, R3, R4, R5, R8, and R9 are defined as in claim 1; Using compound 51 as a raw material, an intermediate compound 56 or 57 is prepared through a selenization reaction, a substitution reaction, and a demethylation reaction. Compound 56 or 57 is hydrolyzed or an amine compound HNR3R5 is reductively aminized to obtain a compound of formula (III); wherein R3, R5, R6, R7, R8, and R9 are defined as in claim 1; Compound 58 is used as a raw material, and intermediate compound 63 is obtained through Suzuki reaction, reduction reaction, and substitution reaction. Compound 63 and amine compound HNR3R5 are subjected to reductive amination to obtain a compound of formula (IV); Among them, R2, R3, R4, R5, R9, R 10 The definition of as in claim 1; Compound 64 is used as a raw material, and an intermediate compound 70 is obtained through Miyaura borylation reaction, Suzuki reaction, reduction reaction, and substitution reaction. Compound 70 and an amine compound HNR3R5 are subjected to reductive amination to obtain a compound of formula (V); Among them, R2, R3, R4, R5, R9, R 11 The definition of is as mentioned above; Using compound 71 as a raw material, a substitution reaction is performed to obtain an intermediate compound 72, and compound 72 is reacted with an amine compound HNR3R5 through reductive amination to obtain a compound of formula (VI); wherein R2, R3, R4, R5, and R8 are as defined above; 5. A pharmaceutical composition, characterized in that The pharmaceutical composition comprises a therapeutically effective amount of an active ingredient and a pharmaceutically acceptable excipient; the active ingredient comprises a selenium-containing compound as described in any one of claims 1 to 3, its stereoisomers, metabolites, metabolic precursors, prodrugs, solvates, crystals or pharmaceutically acceptable salts thereof.

6. Use of the selenium-containing compound according to any one of claims 1 to 3, its stereoisomers, metabolites, metabolic precursors, prodrugs, solvates, crystals or pharmaceutically acceptable salts thereof in the preparation of PD-1 / PD-L1 inhibitor drugs.

7. Use of the selenium-containing compound, its stereoisomers, metabolites, metabolic precursors, prodrugs, solvates, crystals or pharmaceutically acceptable salts according to any one of claims 1 to 3 in the preparation of drugs for treating PD-1 / PD-L1-mediated immunosuppression-related diseases.

8. The use according to claim 7, characterized in that: Diseases related to PD-1 / PD-L1-mediated immunosuppression include cancer.

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