A novel coronavirus main protease inhibitor and its preparation method and application

Abstract

The present invention provides a novel coronavirus main protease inhibitor and a preparation method and application thereof, specifically providing a compound or a pharmaceutically acceptable salt thereof. The beneficial effect of the present invention is that the compound of the present invention can significantly inhibit the activity of the SARS-CoV-2 main protease, and has good application prospects in the preparation of drugs for treating or preventing coronavirus infection.

Description

Technical Field

[0001] The present invention belongs to the technical field of small molecule inhibitors of the main protease of the novel coronavirus and their synthesis methods, and in particular, relates to a main protease inhibitor of the novel coronavirus and its preparation method and application. Background Art

[0002] Coronavirus is a class of pathogens widely found in nature. Its host range is very wide, covering birds, mammals and humans. Since the first coronavirus was isolated in 1965, it has caused many serious human epidemics around the world in the past 60 years. On February 11, 2020, the World Health Organization officially announced that the disease caused by this virus is called COVID-19. The new coronavirus infection (COVID-19) has caused more than 300 million infections and more than 5 million deaths, posing a serious threat to human health and world public health security, and also bringing a serious burden to the recovery of the world economy. Since the outbreak of the new crown epidemic, variants of the new coronavirus have been continuously discovered. The Omicron strain is more contagious than the Delta strain. The risk of reinfection caused by this variant is more than 5 times higher than other strains. The overall risk assessment of the new coronavirus Omicron variant is "very high" in the world, and it may be widely spread in the world. It can be seen that compared with the past, the new coronavirus has a higher degree of variation in its adaptation to the environment. It is precisely because of the high mutation rate and high mutation speed of the new coronavirus that the protection rate of the new coronavirus vaccine has been declining. Even though the new coronavirus vaccine has been vaccinated on a large scale and multiple times around the world, it is still unable to effectively prevent and stop the harm that the virus brings to human health. Therefore, in this case, the development of small molecule drugs against the new coronavirus is particularly necessary.

[0003] At present, studies have found that the main protease of SARS-CoV-2 is involved in the process of hydrolyzing the replicase polyprotein encoded by the coronavirus genome into non-structural proteins necessary for viral genome replication, and thus plays a vital role in the transcription and replication of coronavirus. And there is no homologous protein of the main protease in the human body, so the main protease is a good anti-coronavirus target. Moreover, enzymatic experiments further confirmed that the substrate binding site of the coronavirus main protease is conserved. Therefore, if the hydrolysis of the main protease of SARS-CoV-2 can be inhibited, it will effectively resist the infection of SARS-CoV-2 to the human body. Therefore, the coronavirus main protease is an ideal target for the design of anti-new coronavirus drugs. Based on this, the design, modification and optimization of some small molecule inhibitors were attempted using the crystal structure information of the target protein, and some small molecules were synthesized using the classic structure-based drug design ideas and processes. After verification, it was found that some designed and modified small molecules have significant inhibitory activity against SARS-CoV-2. Summary of the invention

[0004] One object of the present invention is to provide a compound that is a small molecule inhibitor that can effectively inhibit the activity of the main protease of the new coronavirus. The general structural formula of the compound is shown in Formula 1:

[0005]

[0006] Among them, U is

[0007] R1 is selected from the following groups: C1-C6 alkylcarbonyl or cycloalkylcarbonyl, tert-butyloxycarbonyl, benzoyl, isoxazolylcarbonyl, furanylcarbonyl, pyrrolylcarbonyl, thienylcarbonyl, imidazolylcarbonyl, pyrazolylcarbonyl, thiazolylcarbonyl, pyridylcarbonyl, trifluoromethylcarbonyl,

[0008] R2 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl, hydroxymethyl,

[0009] R3 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, hydroxyl, p-methylphenyl, fluorophenyl, fluorobenzyl,

[0010] R4 is selected from the following groups: C1-C6 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl;

[0011] R5 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl.

[0012] Preferably, R1 is the following group:

[0013] R2 is preferably methyl, isopropyl, hydroxymethyl, R3 is preferably isopropyl, tert-butyl, cyclohexyl, benzyl, phenyl, hydroxyl, p-fluorobenzyl,

[0014] R4 is preferably a cyclohexyl group, an isopropyl group, a phenyl group, or a hydrogen atom;

[0015] R5 is preferably isobutyl or isopropyl.

[0016] Preferably, the structure of the compound is one of the following structures,

[0017]

[0018]

[0019]

[0020] Preferably, the structure of the compound is as shown in Formula 2:

[0021]

[0022] Wherein, R1 is selected from the following groups: C1-C6 alkylcarbonyl or cycloalkylcarbonyl, tert-butyloxycarbonyl, benzoyl, isoxazolylcarbonyl, furanylcarbonyl, pyrrolylcarbonyl, thienylcarbonyl, imidazolylcarbonyl, pyrazolylcarbonyl, thiazolylcarbonyl, pyridylcarbonyl, trifluoromethylcarbonyl,

[0023] R2 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl, hydroxymethyl,

[0024] R3 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, hydroxyl, p-methylphenyl, fluorophenyl, fluorobenzyl,

[0025] R4 is selected from the following groups: C1-C6 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl;

[0026] R5 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl.

[0027] Preferably, the structure of the compound is one of the following structures,

[0028]

[0029] Another object of the present invention is to provide a method for synthesizing the small molecule inhibitor, which comprises:

[0030] Removing the amino protecting group R6 in the compound of formula 3, wherein R6 is selected from the group consisting of: tert-butyloxycarbonyl, trifluoroacetyl, benzyloxycarbonyl, methyloxycarbonyl, and allyloxycarbonyl;

[0031] In the presence of a condensing agent, the product of the previous step is condensed with the compound of formula 4 to obtain formula 5;

[0032]

[0033] Among them, U is

[0034] R1 is selected from the following groups: C1-C6 alkylcarbonyl or cycloalkylcarbonyl, tert-butyloxycarbonyl, benzoyl, isoxazolylcarbonyl, furanylcarbonyl, pyrrolylcarbonyl, thienylcarbonyl, imidazolylcarbonyl, pyrazolylcarbonyl, thiazolylcarbonyl, pyridylcarbonyl, trifluoromethylcarbonyl,

[0035] R2 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl, hydroxymethyl,

[0036] R3 is selected from the following groups: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, hydroxyl, p-methylphenyl, fluorophenyl, fluorobenzyl,

[0037] Preferably, the compound of formula 3 is reacted with an acid or a base in an organic solvent at room temperature for 2 to 8 hours to remove the amino protecting group R6, and the organic solvent is removed;

[0038] Then, the obtained product and the compound of formula 4 are dissolved in an aprotic solvent, and the condensing agent and the organic base are added, and the reaction is carried out at room temperature for 16 to 24 hours to obtain the compound of formula 5.

[0039] Preferably, the acid is trifluoroacetic acid and / or hydrochloric acid;

[0040] The alkali is sodium hydroxide and / or sodium methoxide;

[0041] The organic solvent is one or more of CH2Cl2, THF, DMF and dioxane;

[0042] The aprotic solvent is one or more of CH2Cl2, THF, DMF, dioxane, dimethyl sulfoxide, and benzene;

[0043] The condensing agent is one or more of HATU, HBTU, EDCI and HOBT;

[0044] The organic base is one or more of LDA, triethylamine and DIEA.

[0045] Another object of the present invention is to provide a compound and a pharmaceutically acceptable salt thereof for use in the preparation of a medicament for treating or preventing coronavirus infection; preferably, the coronavirus is the new coronavirus SARS-CoV-2.

[0046] The last object of the present invention is to provide a compound and its pharmaceutically acceptable salt for use in the preparation of a new coronavirus main protease inhibitor.

[0047] Using the above technical scheme, relevant experiments have proved that the compound of the present invention can significantly inhibit the activity of the SARS-CoV-2 main protease and has good application prospects in the preparation of drugs for treating or preventing coronavirus infection. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a compound M1 of the embodiment of the present invention 1 H-NMR graph

[0049] Figure 2 is a compound M1 of the embodiment of the present invention 13 C-NMR

[0050] Figure 3 This is the MS spectrum of compound M1 of the present invention.

[0051] Figure 4 is a compound M2 of an embodiment of the present invention 1 H-NMR graph

[0052] Figure 5 is a compound M2 of an embodiment of the present invention 13 C-NMR graph

[0053] Figure 6 This is the MS spectrum of compound M2 of the present invention.

[0054] Figure 7 is a compound M3 of an embodiment of the present invention 1 H-NMR graph

[0055] Figure 8 is a compound M3 of an embodiment of the present invention 13 C-NMR graph

[0056] Fig. 9 This is the MS spectrum of compound M3 of the present invention.

[0057] Fig.10 is a compound M4 of the present invention. 1 H-NMR graph

[0058] Fig.11 is a compound M4 of the present invention. 13 C-NMR graph

[0059] Fig.12 This is the MS spectrum of compound M4 of the present invention.

[0060] Fig.13 is a compound M5 of an embodiment of the present invention 1 H-NMR graph

[0061] Fig.14 is a compound M5 of an embodiment of the present invention 13 C-NMR graph

[0062] Fig.15 This is the MS spectrum of compound M5 of the present invention.

[0063] Fig.16 is a compound M6 of an embodiment of the present invention 1 H-NMR graph

[0064] Fig.17 is a compound M6 of an embodiment of the present invention 13 C-NMR graph

[0065] Fig.18 This is the MS spectrum of compound M6 of the present invention.

[0066] Fig.19 is a compound M7 of an embodiment of the present invention 1 H-NMR graph

[0067] Fig. 20 is a compound M7 of an embodiment of the present invention 13 C-NMR graph

[0068] Fig.21 This is the MS spectrum of compound M7 of the present invention.

[0069] Fig. 22 is a compound M8 of the present invention. 1 H-NMR graph

[0070] Fig.23 is a compound M8 of the present invention. 13 C-NMR graph

[0071] Fig.24 This is the MS spectrum of compound M8 of the present invention.

[0072] Fig.25 is a compound M9 of an embodiment of the present invention 1 H-NMR graph

[0073] Fig.26 is a compound M9 of an embodiment of the present invention 13 C-NMR graph

[0074] Fig. 27 This is the MS spectrum of compound M9 of the present invention.

[0075] Fig.28 is a compound M10 of an embodiment of the present invention 1 H-NMR graph

[0076] Fig.29 is a compound M10 of an embodiment of the present invention 13 C-NMR graph

[0077] Fig.30 This is the MS spectrum of compound M10 of the present invention. DETAILED DESCRIPTION

[0078] The present invention will be further described below in conjunction with embodiments and drawings:

[0079] Unless otherwise defined, all professional terms used hereinafter have the same meaning as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and comparative examples, and are not intended to limit the scope of protection of the present invention. It should be particularly noted that there may be multiple names for the same organic structure, as long as the structure is within the scope of this patent, it belongs to the protection object of this patent.

[0080] Unless otherwise defined, the raw materials, reagents, etc. in the following examples and comparative examples can be purchased from the market or prepared according to reported methods.

[0081] For the convenience of description, some specific terms are used in this article, which are explained one by one below.

[0082] M1-M10 are codes for particularly preferred small molecule inhibitors of the present invention;

[0083] The term “SARS-CoV-2M pro ” refers to the main proteolytic enzyme of the SARS-CoV-2 coronavirus.

[0084] In some structural formulas, "Et" represents ethyl, "Bn" represents benzyl, and "Boc" represents tert-butyloxycarbonyl. "TFA" represents trifluoroacetic acid, "DCM" represents dichloromethane, "EA" represents ethyl acetate, "THF" represents tetrahydrofuran, "DMF" represents N,N-dimethylformamide, "DMSO" represents dimethyl sulfoxide, "Et3N" represents triethylamine, "DIEA" represents N,N-diisopropylethylamine, "EDCI" represents 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, "HATU" represents 2-(7-azobenzotriazole)-N,N,N',N'-tetramethyluronium hexafluorophosphate, and "HOBT" represents 1-hydroxybenzotriazole.

[0085] The structure of the compound of the present invention is as described above, and the structure of the compound of the present invention is shown in general formula 1:

[0086]

[0087] R1 is selected from: C1-C6 alkylcarbonyl or cycloalkylcarbonyl, tert-butyloxycarbonyl, benzoyl, isoxazolylcarbonyl, furanylcarbonyl, pyrrolylcarbonyl, thienylcarbonyl, imidazolylcarbonyl, pyrazolylcarbonyl, thiazolylcarbonyl, pyridylcarbonyl, trifluoromethylcarbonyl, One or more of the following;

[0088] R2 is selected from: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl, hydroxymethyl, One or more of the following;

[0089] R3 is selected from: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, hydroxyl, p-methylphenyl, fluorophenyl, fluorobenzyl, One or more of the following;

[0090] R4 is selected from: one or more of: C1-C6 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, fluorobenzyl;

[0091] R5 is selected from one or more of: C1-C5 alkyl or cycloalkyl, hydrogen atom, phenyl, benzyl, p-methylphenyl, fluorophenyl, and fluorobenzyl.

[0092] The preferred general structural formula of the compound in the present invention is shown in Formula 2:

[0093]

[0094] The selection range of R1, R2, and R3 is consistent with the above and will not be repeated here.

[0095] The preferred specific compounds M1-M10 of the present invention are listed below:

[0096]

[0097]

[0098] Another object of the present invention is to provide a method for synthesizing the small molecule inhibitor, which comprises:

[0099] Removing the amino protecting group R6 in the compound of formula 3, wherein R6 is selected from the group consisting of: tert-butyloxycarbonyl, trifluoroacetyl, benzyloxycarbonyl, methyloxycarbonyl, and allyloxycarbonyl;

[0100] In the presence of a condensing agent, the product of the previous step is condensed with the compound of formula 4 to obtain formula 5;

[0101]

[0102]

[0103] Among them, U, R1, R2, and R3 are consistent with the above-mentioned selection ranges and are not described in detail here.

[0104] The synthesis of the compound of formula 3 can be referred to: Linlin Zhang, Daizong Lin, Yuri Kusov, etc., J. Med. Chem. 2020, 63, 4562-4578; the synthesis of the compound of formula 4 can be referred to: Dawei Ma, Weiqing Xie, Bin Zou, Qiong Lei and Duanqing Pei Tetrahedron Lett. 2004, 45, 8103-8105.

[0105] Specifically, in an organic solvent, the compound of formula 3 is reacted with an acid or a base at room temperature for 2 to 8 hours, preferably 4 to 6 hours, to remove the amino protecting group R6, and the organic solvent is removed; then the obtained product and the compound of formula 4 are dissolved in a non-protonic solvent, a condensing agent and an organic base are added, and the reaction is carried out at room temperature for 16 to 24 hours, preferably 12 to 24 hours, to obtain a compound of formula 5.

[0106] The above-mentioned acid is trifluoroacetic acid and / or hydrochloric acid;

[0107] The base is sodium hydroxide and / or sodium methoxide;

[0108] The organic solvent is one or more of CH2Cl2, THF, DMF and dioxane;

[0109] The aprotic solvent is one or more of CH2Cl2, THF, DMF, dioxane, dimethyl sulfoxide, and benzene;

[0110] The condensing agent is one or more of HATU, HBTU, EDCI and HOBT;

[0111] The organic base is one or more of LDA, triethylamine and DIEA.

[0112] Here are some specific examples:

[0113] The present invention selects the synthesis of compound M1 to illustrate the synthesis method and application of the present invention in detail, but it does not mean to limit the application scope of other compounds of the present invention.

[0114] Example 1

[0115]

[0116] 200 mg of M1-2 was dissolved in 4 mL of DCM, and then 108 μL of DIEA, 269 mg of M1-1 and 299 mg of HATU were added in sequence, and the mixture was stirred at room temperature for 12 h. After the reaction was completed, it was washed with 1 M HCl solution, saturated NaHCO3 solution and saturated NaCl solution in sequence, and the DCM phase was collected, dried with anhydrous sodium sulfate, and then purified on a silica gel column to obtain 276 mg of a white solid, namely M1, with a yield of 62%.

[0117] like Figure 1-Figure 3 As shown, the relevant data of M1 are: 1H NMR (600MHz, DMSO-d6) δ8.21(t,J=6.2Hz,1H),8.09–8.04(m,1H),7.92(d,J=9.0Hz,1H),7.51(d,J=6.0Hz,1H),7.43(dd,J= 9.6,6.0Hz,1H),7.32–7.20(m,5H),6.56–6.55(m,1H),5.79(dd,J=15.0,6.0Hz,1H),4.55(m,1H),4.33(m,1H),4.28–4.24(m ,1H),4.23–4.16(m,2H),3.91(dd,J=6.1,3.2Hz,1H),3.15–3.11(m,1H),3.02(m,1H),2.46(s,3H),2.26–2.21(m,1H),2.18– 2.12(m,1H),1.98(m,2H),1.57(m,2H),1.44–1.36(m,3H),1.30(d,J=7.1Hz,2H),1.24(d,J=3.1Hz,1H),0.86–0.78(m,12H). 13 C NMR (151MHz, DMSO) δ172.23,171.81,171.72,170.06,159.05,158.71,138.64,136.26,128.84,128.58,128.45,128.20,127.48, 101.78,66.40,60.21,56.07,55.35,51.00,49.02,38.70,24.66,23.09,23.04,21.77,21.38,18.44,14.54,12.28.ESI-MS:calcd for C 34 H 47 N7O8[M+H] + :682.79,found 682.71.

[0118] Among them, the preparation process of M1-1 is:

[0119]

[0120] Specifically, the preparation of compound 5:

[0121] Dissolve 1g of sodium hydroxide in 10mL of water, add 5mL of 1,4-dioxane, cool in an ice bath, add 1g of compound 1, then add 1.8g of (Boc)2O, stir at room temperature for 12 hours, adjust pH 4-5 with 1M hydrochloric acid solution, then extract with ethyl acetate, collect ethyl acetate phase, dry over anhydrous sodium sulfate, and remove ethyl acetate by rotary evaporation to obtain 1.7g of oil, i.e., compound 2, with a yield of 95%, and continue to feed without further purification. Dissolve the obtained 1.7g of compound 2 in 25mL of DMF, add 2g of anhydrous potassium carbonate, cool the reaction system in an ice bath, then add 1mL of benzyl bromide, stir at room temperature for 12 hours, then add a small amount of water, stir at room temperature for 30 minutes, filter the reaction system, collect the filtrate, dilute the system with dichloromethane, wash with water, collect the organic phase, dry over anhydrous sodium sulfate, and remove the solvent by rotary evaporation to obtain 2.1g of oil, i.e., compound 3, with a yield of 90%, and continue to feed without further purification. The obtained 2.1g compound 3 was dissolved in 20mL dichloromethane, and then 5mL TFA was added and stirred at room temperature for 4 hours. The solvent was evaporated under reduced pressure, and the obtained oil was dissolved in 20mL dichloromethane. The reaction system was placed in an ice bath, and after cooling, 5mL triethylamine was added, and then 1.9g N-Boc-L-valine, 1.0g HOBT and 1.5g EDCI were added, and the reaction was stirred at room temperature for 12h. The reaction system was washed with 1M hydrochloric acid solution, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution in sequence, and the organic phase was collected, dried by adding anhydrous sodium sulfate, and then the sodium sulfate was filtered off, the solvent was evaporated, and 2.6g of white solid, i.e., compound 5, was obtained by rapid silica gel column chromatography with a yield of 90%.

[0122] The relevant data of compound 5 are: 1 H NMR (400MHz, CDCl3) δ7.35-7.40(m,5H),6.23(d,J=7.0Hz,1H),5.18(d,J=2.8Hz,2H),5.06(d,J=7.6Hz,1H),4.66 -4.72(m,1H),3.85 -3.93(m,1H),1.64-1.71(m,3H),1.46(s,9H),0.91-0.98(m,13H).

[0123] Preparation of compound 7:

[0124] 0.6 g of compound 5 was dissolved in 5 mL of dichloromethane, 1 mL of TFA was added, and the mixture was stirred at room temperature for 4 hours. The solvent was evaporated under reduced pressure, and the mixture was pumped dry. The obtained oil was dissolved in 5 mL of dichloromethane, and then 1.1 mL of triethylamine and 0.3 g of N-Boc-L-alanine were added, followed by 0.2 g of HOBT and 0.3 g of EDCI. The system was stirred at room temperature overnight to react. After the reaction was completed, the mixture was washed with 1 M hydrochloric acid, saturated sodium bicarbonate aqueous solution, and saturated sodium chloride aqueous solution in sequence, the organic phase was collected, dried with anhydrous sodium sulfate, and then the sodium sulfate was filtered off, the organic phase was collected, the solvent was evaporated, and 0.6 g of white solid, i.e., compound 7, was obtained by rapid silica gel column chromatography with a yield of 83%.

[0125] The relevant data of compound 7 are: 1 H NMR (400MHz, CDCl3) δ7.31-7.42(m,5H),6.69-6.78(m,2H),6.35-6.44(m,1H),4.95(d ,J=5.4Hz,2H),4.92-5.03(m,1H),4.24(dd,J=6.6,8.7Hz,1H),4.09-4.19(m,1H),2.13 -2.24(m,1H),1.56-1.69(m,3H),1.44(s,9H),1.35(d,J=7.2Hz,3H),0.89-0.94(m,12H).

[0126] Preparation of compound 9:

[0127] 470 mg of compound 7 was dissolved in 2 ml of dichloromethane, and 0.7 mL of TFA was added. The mixture was stirred at room temperature for 4 hours. After the reaction was complete, the solvent was evaporated under reduced pressure and the mixture was pumped dry. The obtained oil was dissolved in 2 mL of dichloromethane, and then 0.8 mL of triethylamine, 0.11 g of 5-methylisoxazole-3-carboxylic acid, 0.14 g of HOBT and 0.2 g of EDCI were added in sequence. The system was stirred at room temperature for 12 hours. After the reaction was complete, the mixture was washed with 1 M hydrochloric acid solution, saturated sodium bicarbonate and saturated brine in sequence. The organic phase was collected and dried by adding anhydrous sodium sulfate. The sodium sulfate was then filtered off. The organic phase was collected and the solvent was evaporated under reduced pressure. 0.41 g of white solid, i.e., compound 9, was obtained by rapid silica gel column chromatography. The yield was 85%.

[0128] The relevant data of compound 9 are: 1H NMR(600MHz,Chloroform-d)δ7.42–7.31(m,5H),6.74(d,J=8.6Hz,1H),6.45(s,1H),6.37(d,J=8.1Hz,1H),5.18(q,J=12.3Hz,2H),4.75 –4.59(m,2H),4.28(dd,J=8.7,6.7Hz,1H),2.49(s,3H),2.20–2.06(m,1H),1.87–1.53(m,5H),1.48(d,J=7.0Hz,3H),1.08–0.70(m,11H).

[0129] Preparation of compound M1-1:

[0130] 100 mg of compound 9 was dissolved in 1 mL of THF, 9.3 mg of lithium hydroxide and 2 ml of water were added, and the system was stirred overnight to react. After the reaction was complete, 1 M hydrochloric acid solution was added to acidify and the pH was adjusted to 5. The solvent was then evaporated under reduced pressure, and the obtained white solid was washed once with water. The solid was collected and dried in vacuo to obtain 80 mg of white solid, i.e., compound 10, with a yield of 98%.

[0131] The relevant data of compound M1-1 are: 1 H NMR (400 MHz, DMSO-d 6 ): δ12.47(s,1H),8.61(d,J=7.5Hz,1H),8.17(d,J=7.6Hz,1H),7.88(d,J=9.0Hz,1H),6.55(s,1H),4.46 -4.56(m,1H),4.15-4.26(m,2H),2.46(s,3H),1.90 -2.03(m,1H),1.58 -1.66(m,1H),1.43 -1.55(m,2H),1.30(d,J=7.1Hz,3H),0.79-0.90(m,12H).

[0132] Example 2

[0133]

[0134] 250 mg of M2-1 was dissolved in 4 mL of DCM, and 256 mg of HATU, 558 μL of DIEA and 172 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 254 mg of a white solid, namely M2, with a yield of 63%.

[0135] like Figure 4-Figure 6 As shown, the relevant detection data of M2 is: 1 H NMR(600MHz,Chloroform-d)δ7.50(d,J=7.2Hz,1H),7.48(d,J=7.6Hz,1H),7.42–7.37(m,1H),7.37–7.31(m,5H) ,7.29–7.23(m,5H),6.52(d,J=8.0Hz,1H),6.41(m,1H),5.57(d,J=7.1Hz,1H),5.07(d,J=3.9Hz,1H),4.76(p,J=7 .1Hz,1H),4.66–4.60(m,1H),2.81(m,9H),2.46(dd,J=4.0,0.9Hz,3H),1.93(s,1H),1.68–1.52(m,3H),1.48(d, J=7.0Hz,2H),1.43(d,J=7.0Hz,1H),1.31–1.23(m,1H),0.90(dd,J=6.3,1.8Hz,5H),0.72(dd,J=6.6,4.2Hz,1H). 13 C NMR (151MHz, DMSO) δ171.90,171.74,171.63,171.50,159.06,158.63,136.33,128.80,128.49,101.78,66.25,60.21,57.57,57.4 1,54.09,49.09,42.32,38.70,31.42,29.27,28.63,26.00,25.94,21.21,19.55,18.55,18.48,18.35,17.19,14.54,12.94,12.28. MS m / z=716.73[M+1] + ,m / z=714.73[M-1] - .

[0136] Example 3

[0137]

[0138] 238 mg of M3-1 was dissolved in 4 mL of DCM, and 241 mg of HATU, 524 μL of DIEA and 162 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 235 mg of a white solid, namely M3, with a yield of 62%.

[0139] like Figure 7-Figure 9 As shown, the relevant test data of M3 is: 1 H NMR(600MHz,Chloroform-d)δ8.33(d,J=6.4Hz,1H),7.56(t,J=6.2Hz,1H),7.36–7.29(m,5H),7.03(d,J=8.5H z,1H),6.34(s,1H),5.28(m,1H),4.77(p,J=7.1Hz,1H),4.57(m,1H),4.50(d,J=6.2Hz,2H),4.41(dd,J=9.1,6 .1Hz,1H),3.50(s,1H),3.38(td,J=8.7,6.2Hz,2H),2.57–2.47(m,2H),2.45(s,3H),2.08(m,2H),2.04–1.97( m,3H),1.93(m,2H),1.75–1.71(m,3H),1.69–1.58(m,3H),1.55–1.47(m,3H),0.92–0.89(m,6H),0.85(m,6H). 13 C NMR (151MHz, DMSO) δ196.90,178.47,172.57,171.72,170.90,161.33,159.08,158.59,140.95,138.93,128.75,127.76,127.40,101.77,55 .36,51.36,49.04,42.53,38.06,34.14,31.75,29.48,29.15,28.47,2 6.04,24.52,23.26,23.23,22.55,22.29,21.99,18.54,14.40,12.29. MS m / z=722.86[M+1] + ,m / z=720.82[M-1] - .

[0140] Example 4

[0141]

[0142] 269 ​​mg of M4-1 was dissolved in 5 mL of DCM, and 273 mg of HATU, 592 μL of DIEA and 182 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 264 mg of a white solid, namely M4, with a yield of 61%.

[0143] like Figure 10-12 As shown, the relevant detection data of M4 is: 1 H NMR(600MHz,Chloroform-d)δ8.33(d,J=6.3Hz,1H),7.56(t,J=6.2Hz,1H),7.36–7.29(m,5H),7.03(d,J=8. 6Hz,1H),6.34(d,J=1.0Hz,1H),5.28(m,1H),4.77(p,J=7.1Hz,1H),4.57(m,1H),4.50(d,J=6.2Hz,2H),4.41 (dd,J=9.1,6.1Hz,1H),3.50(s,1H),3.37(dd,J=8.7,6.1Hz,2H),2.56–2.51(m,1H),2.46–2.44(m,3H),2.0 8(m,2H),2.04–1.88(m,5H),1.74(m,4H),1.68–1.57(m,5H),1.50(d,J=7.0Hz,3H),1.29(d,J=17.4Hz,10H). 13 C NMR (151MHz, DMSO) δ196.90,178.47,172.57,171.72,170.90,161.33,159.08,158.59,140.95,138.93,128.75,127.76,127.40,101.77,55 .36,51.36,49.04,42.53,38.06,34.14,31.75,29.48,29.15,28.47,2 6.04,24.52,23.26,23.23,22.55,22.29,21.99,18.54,14.40,12.29. MS m / z=722.82[M+1] + ,m / z=720.64[M-1] - .

[0144] Example 5

[0145]

[0146] 270 mg of M5-1 was dissolved in 5 mL of DCM, and 281 mg of HATU, 610 μL of DIEA and 188 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 265 mg of a white solid, namely M5, with a yield of 61%.

[0147] like Figure 13-Figure 15 As shown, the relevant test data of M5 is: 1 H NMR (600MHz, DMSO-d6) δ9.24(t,J=6.3Hz,1H),8.46(d,J=7.5Hz,1H),8.27(d,J=8.9Hz,1H),8.04(dd,J=17.0,8.4Hz,2H),7.65(s,1H) ,7.33–7.21(m,5H),6.57(d,J=1.1Hz,1H),5.08(ddd,J=11.2,7.6,3.2Hz,1H),4.39–4.36(m,1H),4.34–4.29(m,2H),4.20(dd,J=8.8, 7.3Hz,1H),3.18(s,2H),3.08(td,J=9.4,7.2Hz,1H),2.46(d,J=0.9Hz,3H),2.38(tdd,J=10.4,8.3,3.7Hz,1H),2.20–2.14(m,1H),2. 08(dt,J=13.7,6.8Hz,1H),1.97–1.86(m,2H),1.73–1.51(m,3H),1.45–1.37(m,2H),0.88(dd,J=6.7,3.4Hz,6H),0.86–0.80(m,12H). 13 C NMR (151MHz, DMSO) δ196.89,178.47,172.63,171.85,170.98,170.53,161.30,159.07,158.80,140.86,138.93,130.39,128.74,128.55,127.39 ,101.81,58.73,58.01,52.46,51.26,49.06,42.52,41.24,38.10,31.74 ,31.04,27.67,24.47,23.34,22.11,19.57,19.53,18.83,18.74,12.29. MS m / z=710.67[M+1] + ,m / z=708.85[M-1] - .

[0148] Example 6

[0149]

[0150] 237 mg of M6-1 was dissolved in 5 mL of DCM, and 229 mg of HATU, 497 μL of DIEA and 153 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 230 mg of a white solid, namely M6, with a yield of 62%.

[0151] like Figure 16-18 As shown, the relevant test data of M6 is: 1 H NMR (600MHz, DMSO-d6) δ9.25(t,J=6.4Hz,1H),8.51(dd,J=8.3,4.7Hz,1H),8.44(dd,J=14.4,8.2Hz,1H),7.65(s,1H),7.55–7.51(m,1 H),7.46–7.43(m,1H),7.41–7.15(m,10H),6.59(dd,J=7.1,1.1Hz,1H),5.07(m,1H),4.33(dd,J=7.1,2.5Hz,1H),4.31(d,J=6.6Hz,1H) ,4.29–4.17(m,2H),3.07(m,1H),2.47–2.47(s,3H),2.37(m,1H),2.14(m,1H),1.99–1.85(m,2H),1.64(m,3H),1.43(t,J=7.4Hz,1H),1 .39–1.34(m,1H),1.25(d,J=14.0Hz,2H),0.89(d,J=6.6Hz,1H),0.88–0.79(m,7H),0.76(d,J=6.6Hz,1H),0.64(dd,J=8.2,6.8Hz,3H). 13 C NMR (151MHz, DMSO) δ171.91,171.74,171.70,171.55,159.06,158.64,136.30,128.82,128.54,101.77,66.33,60.20,57.97,57.5 1,55.35,54.08,49.08,42.32,38.69,31.37,30.19,21.20,19.56,19.29,18.58,18.54,18.48,18.38,17.19,14.53,12.93,12.28. MS m / z=744.59[M+1] + ,m / z=742.76[M-1] - .

[0152] Example 7

[0153]

[0154] 249 mg of M7-1 was dissolved in 5 mL of DCM, and 280 mg of HATU, 609 μL of DIEA and 188 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 258 mg of a white solid, namely M7, with a yield of 62%.

[0155] like Figure 19-21 As shown, the relevant test data of M7 is: 1 H NMR (600MHz, DMSO-d6) δ8.61(dt,J=14.9,6.1Hz,1H),8.53(dd,J=7.4,1.5Hz,1H),7.99(dd,J=9.5,7.8Hz,1H),7.87(dq,J =7.2,1.4Hz,2H),7.74(dd,J=8.8,3.7Hz,1H),7.55–7.52(m,1H),7.47(t,J=7.9Hz,2H),7.32–7.19(m,5H),4.52(td,J=7. 3,2.8Hz,1H),4.35–4.07(m,4H),3.18(d,J=5.2Hz,1H),3.12–3.06(m,1H),3.03–2.97(m,1H),2.25–2.13(m,2H),2.12–1. 99(m,3H),1.97–1.87(m,2H),1.57(dq,J=13.5,6.7Hz,1H),1.43(m,3H),1.32(dd,J=7.1,2.3Hz,3H),0.91–0.76(m,12H). 13 C NMR (151MHz, DMSO) δ178.65,172.73,172.62,172.56,172.01,171.67,171.53,159.06,159.00,101.73,5 2.37,51.29,50.69,49.20,48.81,41.05,38.09,32.65,27.61,24.77,23.50,21.66,18.30,18.27,12.28. MS m / z=677.67[M+1] + ,m / z=675.72[M-1] - .

[0156] Example 8

[0157]

[0158] 212 mg of M8-1 was dissolved in 4 mL of DCM, and 245 mg of HATU, 532 μL of DIEA and 164 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 214 mg of a white solid, namely M8, with a yield of 60%.

[0159] like Figure 22-Figure 24 As shown, the relevant test data of M8 is: 1 H NMR (600MHz, DMSO-d6) δ8.27–8.22(m,2H),8.12–8.05(m,1H),7.96(dd,J=8.7,6.0Hz,1H),7.78(td,J=9.4,4.9Hz, 1H),7.72(t,J=1.6Hz,1H),7.57–7.51(m,1H),7.38–7.25(m,2H),7.25–7.20(m,2H),6.89(dp,J=2.0,1.1Hz,1H),4 .50(dd,J=8.3,6.1Hz,1H),4.37–4.19(m,3H),4.15(m,1H),3.22–2.95(m,3H),2.34–2.12(m,2H),2.11–1.99(m,2H ),1.98–1.83(m,2H),1.60(qd,J=12.5,11.8,7.9Hz,2H),1.50–1.35(m,3H),1.28–1.26(m,3H),0.91–0.78(m,12H). 13 C NMR (151MHz, DMSO) δ178.92,172.50,171.79,171.74,171.00,170.18,167.86,159.07,158.55,136.47,136.20,129.16,127.66,101.77,76 .14,57.15,51.82,49.04,47.82,42.26,37.68,33.17,29.44,28.44,2 8.04,26.34,26.08,24.50,23.19,22.32,21.12,21.02,18.59,12.29. MS m / z=667.63[M+1] + ,m / z=665.80[M-1] - .

[0160] Example 9

[0161]

[0162] 230 mg of M9-1 was dissolved in 4 mL of DCM, and 265 mg of HATU, 575 μL of DIEA and 177 mg of M1-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 236 mg of a white solid, namely M9, with a yield of 61%.

[0163] like Figure 25-27 As shown, the relevant test data of M9 is: 1 H NMR (600MHz, DMSO-d6) δ8.21(t,J=6.2Hz,1H),8.08–8.03(m,1H),7.92(d,J=9.0Hz,1H),7.51(d,J=6.0Hz,1H),7.43(dd,J=9.6,6.0Hz,1H ),7.32–7.20(m,5H),6.57–6.51(m,1H),5.79(dd,J=14.9,6.0Hz,1H),4.57–4.51(m,1H),4.33(ddd,J=15.0,6.7,2.4Hz,1H),4.28–4.24(m ,1H),4.23–4.13(m,2H),3.91(dd,J=6.1,3.2Hz,1H),3.16–3.08(m,1H),3.02(td,J=9.3,7.1Hz,1H),2.46(s,3H),2.27–2.21(m,1H),2.14 (ddt,J=12.0,8.6,4.9Hz,1H),2.02–1.91(m,2H),1.46–1.36(m,1H),1.32(dd,J=14.2,7.1Hz,3H),1.26–1.21(m,2H),0.90–0.72(m,12H). 13C NMR(151MHz,DMSO)δ196.80,178.53,172.83,172.26,171.66,170.85,16 1.24,159.01,158.63,138.95,128.74,127.74,127.38,101.69,57.81,55 .37,52.75,50.97,49.03,46.16,42.51,38.22,31.75,29.48,28.25,27. 59,26.24,26.01,24.50,23.50,22.55,21.73,18.98,14.40,12.28,9.06. MS m / z=668.61[M+1] + .

[0164] Example 10

[0165]

[0166] 209 mg of M10-1 was dissolved in 4 mL of DCM, and 212 mg of HATU, 460 μL of DIEA and 138 mg of M10-2 were added in sequence, and stirred overnight. After the reaction, the mixture was washed with 1 M hydrochloric acid solution, saturated NaHCO3 solution and saturated sodium chloride solution in sequence, and the DCM phase was collected, dried over anhydrous sodium sulfate, and then spin-dried to obtain an oily substance, which was purified by silica gel to obtain 206 mg of a white solid, namely M10, with a yield of 62%.

[0167] like Figure 28-Figure 30 As shown, the relevant test data of M10 is: 1H NMR (600MHz, DMSO-d6) δ8.58–8.53(m,1H),8.07–8.00(m,1H),7.89(dd,J=9.0,2.1Hz,1H),7.85–7.83(m,1H),7.54(d,J=9.0H z,1H),6.55(s,1H),4.50(p,J=7.1Hz,1H),4.29(m,1H),4.25–4.18(m,2H),3.19–3.11(m,2H),3.04–2.96(m,1H),2.47(s,3H) ,2.13(s,1H),2.10–2.03(m,3H),1.92–1.86(m,1H),1.65(d,J=14.1Hz,4H),1.57(dd,J=12.5,5.7Hz,3H),1.43–1.32(m,3H), 1.29(d,J=7.0Hz,3H),1.26–1.17(m,6H),1.08(m,6H),1.01–0.89(m,3H),0.85(t,J=6.3Hz,3H),0.81(dd,J=9.0,6.5Hz,3H). 13 C NMR (151MHz, DMSO) δ195.57,178.51,171.73,159.07,140.94,132.86,130.48,128.60,101.77,94.49,70.26,59.72,57.24,55.36,52.46,51.37 ,49.06,48.52,42.17,41.28,38.04,32.22,29.46,28.46,27.96,27.59 ,26.33,26.06,25.47,25.18,24.50,23.23,22.33,21.94,18.54,12.29. MS m / z=714.59[M+1] + ,m / z=712.89[M-1] - .

[0168] According to the M1-M10 obtained above, the above small molecule inhibitors were tested for their effects on SARS-CoV-2 M pro Inhibitory activity studies were performed.

[0169] Research method: To identify whether the small molecule inhibitors obtained above can inhibit SARS-CoV-2M pro activity, this study constructed SARS-CoV-2M proActivity evaluation system: Based on the principle of fluorescence resonance energy transfer, Dabcyl-KTSAVLQSGFRKME-Edans (purchased from Beyotime) was used as the reaction substrate to evaluate the activity of small molecule inhibitors against SARS-CoV-2M. pro The substrate was M pro After cleavage, the Edans fluorescent group is generated. The maximum excitation wavelength of Edans is 340nm and the maximum emission wavelength is 490nm. M is detected by measuring fluorescence. pro activity.

[0170] First, SARS-CoV-2M pro Determination of use concentration:

[0171] S1: Prepare reaction buffer: 20 mM Hepes, 120 mM NaCl, 0.4 mM EDTA, 4 mM DTT, 20% glycerol, pH = 7.5;

[0172] S2: Prepare substrate solution: dilute the reaction substrate Dabcyl-KTSAVLQSGFRKME-Edans with DMSO to a final concentration of 500 μM;

[0173] S3: The purified SARS-CoV-2M pro Replace with the reaction buffer obtained in S1 above using a dialysis tube, and dilute with the reaction buffer to 4 μM, 2 μM, 1 μM, 0.5 μM, 0.25 μM, and 0.125 μM;

[0174] S4: Pipette 100 μL of all the above concentrations of SARS-CoV-2M pro Add them to black 96-well plates respectively, conduct two independent experiments, and perform three replicate wells each time. Place the 96-well plate in a thermostatic homogenizer and incubate for 30 min at 30°C.

[0175] S5: After the incubation is completed, the fluorescence value is measured using an ELISA reader, and the conditions are set as an excitation wavelength of 340 nm and an emission wavelength of 490 nm, and the data is saved as the background value;

[0176] S6: Add 2 μL of 500 μM coronavirus main protein fluorescent substrate to the 96-well plate. In the same way as step S4, set up two independent experiments, with three replicates for each experiment, and incubate in a constant temperature homogenizer for 60 minutes at 30°C.

[0177] S7: After the incubation is completed, the fluorescence value is measured using an ELISA reader, the conditions are set as an excitation wavelength of 340 nm and an emission wavelength of 490 nm, and the data is saved as the reaction value.

[0178] Data processing: actual response value (△RFU) = response value - background value, dilute SARS-CoV-2M pro The logarithm of the concentration with base 10 was taken as the X-axis, and the corresponding △RFU was taken as the Y-axis. The data were processed using GraphPad Prism 8. According to the experimental results, SARS-CoV-2M pro The concentration used was determined to be 1 μM.

[0179] Then M1-M10 was used to detect SARS-CoV M pro Determination of inhibitory effect:

[0180] The purified SARS-CoV-2M pro Dilute to a final concentration of 2 μM, M1-M10 was diluted 4-fold with the above buffer in 6 gradients, with the highest concentration being 100 μM. The positive reference drug was selected and has been reported to effectively inhibit SARS-CoV-2M pro Active GC376 was diluted to 100 μM in reaction buffer; three control experimental groups were set up:

[0181] Drug group: 50 μL SARS-CoV-2M was drawn pro (2 μM) and 50 μL of the drug to be tested (any one of M1-M10) were added to a black 96-well plate;

[0182] Positive drug group: 50 μL SARS-CoV-2M pro (2 μM) and 50 μL GC376 (100 μM) were added to a black 96-well plate;

[0183] No drug control group: 50 μL SARS-CoV-2M pro (2 μM) and 50 μL of reaction buffer were added to a black 96-well plate.

[0184] Adoption and SARS-CoV-2M pro The same determination method as the concentration determination step was used for determination, and data processing was as follows: actual response value = response value - background value, inhibition rate = (actual response value of the non-drug group - actual response value of the drug group) / actual response value of the non-drug group × 100%.

[0185] Results and Analysis:

[0186] M1-M10 vs SARS-CoV-2M pro The inhibitory activity is shown in Table 1:

[0187] Table 1 IC values ​​of M1-M10 for the main protease of novel coronavirus 50

[0188]

[0189]

[0190] The test results show that M1-M10 is effective against SARS-CoV-2M pro It has significant inhibitory activity.

[0191] In summary, the present invention provides a novel coronavirus main protease inhibitor represented by Formula 1 and Formula 2, and a preparation method and application thereof. The compounds represented by Formula 1 and Formula 2 can effectively inhibit SARS-CoV-2M pro Active, can be used to prepare SARS-CoV-2M pro The compound of the present invention has very good application prospects in the preparation of SARS-CoV-2 M pro inhibitors and anti-SARS-CoV-2 drugs.

[0192] The references involved in the present invention, including patent documents, academic papers, publications, etc., are all included in this article in their entirety by reference.

[0193] It should be noted that the various experimental operations involved in the present invention are all routine techniques in the field. If not specifically described herein, ordinary technicians in the field can implement them by referring to various commonly used reference books, scientific and technological literature or related instructions, manuals, etc. before the filing date of the present invention.

[0194] Among the various experimental supplies (including but not limited to: chemical reagents, biological products, cells, organisms, instruments, etc.) involved in this article, for those that are special or difficult to obtain, the manufacturers, references or detailed preparation methods have been noted in the text; those that are not specifically stated are all conventional experimental supplies, which can be easily obtained in various ways (such as purchase, self-preparation, etc.) before the filing date of this invention. It should be understood that without departing from the spirit and scope of the present invention, ordinary technicians in this field can make various changes and improvements in form and details, and these are considered to fall within the scope of protection of the present invention.

Claims

1. A compound, or a pharmaceutically acceptable salt thereof, characterized in that: The general structural formula of the compound is shown in Formula 2: R1 is benzoyl, furanylcarbonyl or R2 is methyl, isopropyl or phenyl; R3 is cyclohexyl or phenyl; R4 is isopropyl, cyclohexyl or phenyl; R5 is isobutyl or isopropyl.

2. A compound according to claim 1, or a pharmaceutically acceptable salt thereof, characterized in that: The structure of the compound is one of the following structures, 3. A method for preparing the compound according to claim 1, or a pharmaceutically acceptable salt thereof, characterized in that: Removing the amino protecting group R6 in the compound of formula 3, wherein R6 is selected from the group consisting of: tert-butyloxycarbonyl, trifluoroacetyl, benzyloxycarbonyl, methyloxycarbonyl, and allyloxycarbonyl; In the presence of a condensing agent, the product of the previous step is condensed with the compound of formula 4 to obtain formula 5; R1 is benzoyl, furanylcarbonyl or R2 is methyl, isopropyl or phenyl; R3 is cyclohexyl or phenyl; R4 is isopropyl, cyclohexyl or phenyl; R5 is isobutyl or isopropyl.

4. A method for preparing a compound according to claim 3, or a pharmaceutically acceptable salt thereof, characterized in that: In an organic solvent, react the compound of formula 3 with an acid or a base at room temperature for 2 to 8 hours to remove the amino protecting group R6, and remove the organic solvent; Then, the obtained product and the compound of formula 4 are dissolved in an aprotic solvent, and the condensing agent and the organic base are added, and the reaction is carried out at room temperature for 16 to 24 hours to obtain the compound of formula 5.

5. A method for preparing a compound according to claim 4, or a pharmaceutically acceptable salt thereof, characterized in that: The acid is trifluoroacetic acid and / or hydrochloric acid; The alkali is sodium hydroxide and / or sodium methoxide; The organic solvent is one or more of CH2Cl2, THF, DMF and dioxane; The aprotic solvent is one or more of CH2Cl2, THF, DMF, dioxane, dimethyl sulfoxide, and benzene; The condensing agent is one or more of HATU, HBTU, EDCI and HOBT; The organic base is one or more of LDA, triethylamine and DIEA.

6. Use of a compound as claimed in claim 1 or 2, or a pharmaceutically acceptable salt thereof, in the preparation of a medicament for treating or preventing coronavirus infection, wherein: The coronavirus is the new coronavirus SARS-CoV-2.

7. Use of a compound as claimed in claim 1 or 2, or a pharmaceutically acceptable salt thereof, in the preparation of a main protease inhibitor of a novel coronavirus.

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