Zanamivir and derivative thereof-adamantane derivative covalent conjugate and anti-influenza virus application thereof

Abstract

The invention provides zanamivir and derivatives thereof, namely adamantane derivative covalent conjugates and application of the zanamivir and the derivatives thereof in resisting influenza viruses. The structure of the zanamivir and the derivative thereof-adamantane derivative covalent conjugate is as shown in formula I in the specification. The invention also provides a method for preparing the zanamivir and the derivative of the zanamivir-adamantane derivative covalent conjugate and a pharmaceutical composition containing the zanamivir and the derivative of the zanamivir-adamantane derivative covalent conjugate. The covalent conjugate provided by the invention not only can improve the pharmacokinetic property of zanamivir, but also has the activity of an M2 ion channel / NA enzyme for inhibiting double targets, can efficiently inhibit influenza viruses, and has relatively high safety.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pharmaceutical chemistry. Specifically, the present application relates to a covalent conjugate of zanamivir and its derivative, adamantane derivative, and the use thereof for anti-influenza virus. BACKGROUND

[0002] Influenza, also known as flu, is an acute viral respiratory system disease with symptoms similar to common cold, and its culprit is influenza virus (IAV). It can infect the respiratory system of the host, leading to a series of respiratory symptoms, including fever, chills, fatigue, headache, cough, sore throat, loss of appetite, muscle and joint pain, etc. In severe cases, it can cause serious lung damage to patients, and even endanger the lives of patients. The number of deaths worldwide due to influenza reaches 500,000 per year. As a kind of zoonotic pathogen, the ecology and epidemiology of influenza virus are very complex, involving multiple hosts including humans, poultry and livestock. Since the Spanish flu outbreak in 1918, there have been several outbreaks of influenza in pigs and poultry, including swine flu and avian flu. This not only poses a great threat to human health, but also causes great harm to social production and life and economic development. Therefore, the research and development of anti-influenza virus vaccines and drugs are both important and urgent.

[0003] However, the current seasonal influenza vaccine has the following shortcomings: 1) the structure of hemagglutinin (HA) of influenza virus has high variability, leading to antigenic drift, making it difficult to match the developed influenza vaccine with the prevalent influenza strain, thereby reducing the preventive effect of the influenza vaccine, and even being ineffective; 2) influenza vaccines produced by chicken embryos are prone to adaptive mutations of the virus, resulting in a decrease in the effect of the influenza vaccine; 3) the current influenza virus vaccine has poor immunogenicity, and is difficult to induce a high level of antibody response; 4) the current influenza virus vaccine is difficult to achieve broad-spectrum and long-term prevention; 5) the currently developed M2e antibody can only reduce the symptoms of severe patients, but cannot neutralize the virus itself. These shortcomings mean that it is still very difficult to eradicate the threat of influenza to humans through universal influenza vaccine means.

[0004] Current anti-influenza drugs / inhibitors mainly target several biological macromolecular targets that play important roles in the life cycle of influenza virus, namely M2 ion channel, HA, NA and RNP. The first synthetic compound approved for the treatment of influenza was amantadine. Amantadine and rimantadine prevent IAV from fusing with host cells by targeting and inhibiting the M2 ion channel transport of protons on the IAV envelope, thus blocking viral entry into cells and inhibiting the replication of influenza virus. However, IAVs quickly developed significant resistance to amantadine and rimantadine. Therefore, amantadine and rimantadine are no longer recommended by the FDA as a treatment for seasonal influenza. Researchers then considered designing M2 ion channel protein inhibitors with innovative scaffolds that could reduce the resistance of resistant strains to M2 ion channel protein inhibitors. Kurtz et al. designed and synthesized a spiro compound, BL-1743, and replaced the amino group with a more positively charged guanidino group, but the mutant strain still remained highly resistant to the compound (see Kurtz S et al., Growth impairment resulting from expression of influenza virus M2 protein in Saccharomyces cerevisiae: identification of a novel inhibitor of influenza virus [J]. Antimicrobial Agents and Chemotherapy, 1995, 39(10): 2204-2209).Wang et al. and Balannik et al. designed and synthesized a series of spirocyclic analogs of BL-1743, but only weak inhibitory activity against V27A mutant (see Wang J et al., Discovery of spiro-piperidine inhibitors and their modulation of the dynamics of the M2 proton channel from influenza A virus [J]. Journal of the American Chemical Society, 2009, 131(23): 8066-8076; Balannik V et al., Design and pharmacological characterization of inhibitors of amantadine-resistant mutants of the M2 ion channel of influenza A virus [J]. Biochemistry, 2009, 48(50): 11872-11882, respectively).

[0005] The surface of influenza A virus contains NA enzyme, which plays an important role in desialylation during the maturation stage of influenza virus, so the development of neuraminidase inhibitors (NAIs) is particularly important. The existing NA enzyme inhibitors are mainly oseltamivir (OSV) and zanamivir (ZNV). The NA enzyme of IAV also produces drug-resistant mutations under drug pressure, and the level of resistance to zanamivir is lower than that of oseltamivir, but the poor pharmacokinetics of zanamivir affects its wide application in the clinic.

[0006] Therefore, it is of great significance to develop a drug that can efficiently inhibit influenza virus, especially influenza A virus. SUMMARY

[0007] In view of the above problems, the purpose of the present application is to provide a zanamivir and derivative-adamantane derivative covalent conjugate and its anti-influenza virus use. The present inventors have found that by coupling zanamivir and its derivatives and adamantane derivatives together through covalent bond, a new double-target twin drug can be obtained, which can efficiently inhibit influenza virus and has high safety. Therefore, the present application provides a zanamivir and derivative-adamantane derivative covalent conjugate and its anti-influenza virus use.

[0008] In the present application, some terms are defined as follows. Terms other than these have meanings commonly known in the art to which the present application pertains.

[0009] As used herein, the term "C1-C6alkyl" denotes an alkyl group having 1 to 6, in particular up to 4 carbon atoms, the group being straight-chained or branched with a single or multiple branching, for example butyl, such as n-butyl, sec-butyl, iso-butyl, tert-butyl; propyl, for example n-propyl or iso-propyl; ethyl or methyl; more particularly methyl, iso-propyl or tert-butyl.

[0010] As used herein, the term "alkoxy" refers to "alkyl-O-" and in particular methoxy, ethoxy, iso-propoxy or tert-butoxy.

[0011] As used herein, the term "Boc group" refers to "tert-butyloxycarbonyl", which consists of one tert-butyl and one oxycarbonyl group, the chemical structure of which is (CH3)3C-O-CO-.

[0012] As used herein, the term "Ac group" refers to "acetyl", the chemical structure of which is CH3CO-.

[0013] As used herein, the term "Me group" refers to "methyl".

[0014] As used herein, the term "pharmaceutically acceptable excipient" can include solvents, dispersion media, coatings, surfactants, antioxidants, preservatives (e.g., antibacterial and antifungal agents), isotonic agents, absorption delaying agents, salts, drug stabilizers, binders, excipients, disintegration agents, lubricants, sweetening agents, flavoring agents, colorants, and the like, and combinations thereof, as would be known to one of ordinary skill in the art, except insofar as any conventional excipient is incompatible with the active ingredient, as such, its use in the treatment compositions or pharmaceutical compositions is contemplated.

[0015] The above object of the present application is achieved by providing the following technical solutions:

[0016] In a first aspect, the present application provides a compound represented by Formula I, or a pharmaceutically acceptable salt or hydrate thereof,

[0017]

[0018] wherein,

[0019] R1is selected from the group consisting of -NHR5, -NH3 + Y – , -NR5(C=NH)NH2and -NR5(C=NH2 + )NH2Y –wherein R5is selected from H, unsubstituted C1-C6straight or branched chain alkyl, C1-C6straight or branched chain alkyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkenyl, C2-C6straight or branched chain alkenyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkynyl, C2-C6straight or branched chain alkynyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C1-C6straight or branched chain alkoxy, C1-C6straight or branched chain alkoxy substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted aryl, aryl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted aralkyl, aralkyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy; wherein Y – is a negative counterion;

[0020] R2is unsubstituted C1-C6straight or branched chain alkyl or C1-C6straight or branched chain alkyl substituted with halogen;

[0021] R3and R4are each independently selected from H, unsubstituted C1-C6straight or branched chain alkyl, C1-C6straight or branched chain alkyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkenyl, C2-C6straight or branched chain alkenyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkynyl, C2-C6straight or branched chain alkynyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy;

[0022] A is selected from , , , , and ;

[0023] R6and R 16 are each independently selected from H, halogen, hydroxy, unsubstituted C1-C6straight or branched chain alkyl, C1-C6straight or branched chain alkyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkenyl, C2-C6straight or branched chain alkenyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy, unsubstituted C2-C6straight or branched chain alkynyl, C2-C6straight or branched chain alkynyl substituted with hydroxy, amino, C1-C6straight or branched chain alkanoyl, or carboxy;

[0024] R7and R 11Each is independently selected from the following: unsubstituted C1-C6 straight-chain or branched alkylene groups, C1-C6 straight-chain or branched alkylene groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkenyl groups, and C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups;

[0025] R8, R9, R 10 and R 12 Each of the following groups is independently selected from unsubstituted C1-C6 straight-chain or branched alkyl groups, C1-C6 straight-chain or branched alkyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkenyl groups, C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkynyl groups, and C2-C6 straight-chain or branched alkynyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; wherein n1 and n4 are each independently selected from integers from 0 to 10; n2 is selected from integers from 0 to 8; and n3 is selected from integers from 0 to 11.

[0026] R 13 R 14 and R 15 Each is independently selected from H, unsubstituted C1-C6 straight-chain or branched alkyl, C1-C6 straight-chain or branched alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkenyl, C2-C6 straight-chain or branched alkenyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkynyl, and C2-C6 straight-chain or branched alkynyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl;

[0027] X is either O or NH;

[0028] L is selected from the unsubstituted C1-C bond. 60 Straight-chain or branched alkylene groups, C1-C6 straight-chain or branched alkyl acyl groups or carboxyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkyl groups or carboxyl groups. 60 Straight-chain or branched alkylene, unsubstituted C2-C 60 Straight-chain or branched subalkenyl groups, C2-C substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl, or carboxyl groups. 60 Straight-chain or branched alkenyl groups, -(CR 17 R 18 -CR 19 R 20 -O) n5- Unsubstituted arylene, arylene substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted arylene alkyl, arylene alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted heterocyclic group containing 1 to 3 heteroatoms selected from N, S or O, heterocyclic group containing 1 to 3 heteroatoms selected from N, S or O substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; wherein, R 17 R 18 R 19 and R 20 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group; n5 is selected from integers from 0 to 50.

[0029] According to some embodiments of the present invention, Y – Selected from chloride ions, bromide ions, iodide ions, acetate ions, trifluoroacetate ions, phosphate ions, diphosphate ions, nitrate ions, sulfate ions, benzenesulfonate ions, benzoate ions, salicylate ions, hydroxynaphthyl ions, fumarate ions, maleate ions, lactate ions, malic acid, succinate ions, tartrate ions, citrate ions, glutamate ions, gluconeate ions, and stearate ions.

[0030] According to some embodiments of the present invention, R1 is -NR5(C=NH)NH2, wherein R5 is H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, preferably H.

[0031] According to some embodiments of the present invention, R2 is an unsubstituted C1-C3 straight-chain or branched alkyl group or a halogen-substituted C1-C3 straight-chain or branched alkyl group, preferably CH3 or CF3.

[0032] According to some embodiments of the present invention, R3 and R4 are each independently H, or unsubstituted C1-C6 straight-chain or branched alkyl groups; preferably, R3 and R4 are H.

[0033] According to some embodiments of the present invention, R6 and R 16 Each is independently selected from H, halogens and hydroxyl groups, preferably each is independently selected from H, Br and hydroxyl groups.

[0034] According to some embodiments of the present invention, R7 and R 11 Each is independently a bonded or unsubstituted C1-C6 straight-chain or branched alkylene group, preferably an independently a bonded or unsubstituted C1-C3 alkylene group.

[0035] According to some embodiments of the present invention, R8, R9, R 10 and R 12Each is an unsubstituted C1-C6 straight-chain or branched alkyl group, wherein n1, n3 and n4 are each independently selected from integers from 0 to 5, preferably 0, and n2 is selected from integers from 0 to 4, preferably 0.

[0036] According to some embodiments of the present invention, R 13 R 14 and R 15 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, preferably an unsubstituted C1-C3 alkyl group.

[0037] According to some embodiments of the invention, L is selected from unsubstituted C1-C. 60 Straight-chain or branched alkylene, -(CR 17 R 18 -CR 19 R 20 -O) n5 - An unsubstituted subheterocyclic group comprising 1 to 3 heteroatoms selected from N, S, or O, wherein R 17 R 18 R 19 and R 20 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, and n5 is selected from integers from 0 to 20; more preferably, L is selected from -(CH2). n6 -,-(CH2-CH2-O) n5 -and , where n5 and n6 are each independently selected from integers from 1 to 10.

[0038] According to some embodiments of the present invention, the compound has the structure shown in Formula II:

[0039] .

[0040] According to some embodiments of the present invention, A is selected from , , , , , , , , , , , , , and .

[0041] According to some embodiments of the present invention, the compound is selected from the following:

[0042]

[0043]

[0044] In a second aspect, the present invention provides a method for preparing the compound according to the first aspect of the present invention, or a pharmaceutically acceptable salt or hydrate thereof, comprising the following steps:

[0045]

[0046] The compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate, is reacted with compound AH, or its pharmaceutically acceptable salt or hydrate, to obtain the compound shown in Formula II, or its pharmaceutically acceptable salt or hydrate.

[0047] Wherein, the compound AH is selected from , , , , and ;

[0048] R' is methyl or tert-butyl.

[0049] According to some embodiments of the present invention, the method includes the following steps:

[0050]

[0051] (1) The compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate, is coupled with compound AH, or its pharmaceutically acceptable salt or hydrate, to obtain intermediate 4, or its pharmaceutically acceptable salt or hydrate;

[0052] (2) Remove the ketal, Boc and R' protecting groups from the intermediate 4 or its pharmaceutically acceptable salt or hydrate.

[0053] According to some embodiments of the present invention, the compound AH is selected from... , , , , , , , , , , , , , and .

[0054] According to some embodiments of the present invention, the coupling reaction is carried out under the following conditions: at 15-30°C for 10-18 hours in the presence of a catalyst and a solvent; preferably, the catalyst is 4-dimethylaminopyridine (DMAP); preferably, the solvent is pyridine.

[0055] According to some embodiments of the present invention, the removal of the ketal, Boc, and R' protecting groups is carried out under the following conditions:

[0056] When R' is methyl: (i) in the presence of an alkaline auxiliary agent, in a dioxane-H2O system with a volume ratio of 3:(0.5-1.5), react at 15-30°C for 0.1-1 hours; preferably, the alkaline auxiliary agent is KOH; (ii) the product obtained in step (i) is reacted in a trifluoroacetic acid-dichloromethane (TFA-DCM) system with a volume ratio of 1:(0.5-1.5) for 1-5 hours at 15-30°C;

[0057] When R' is tert-butyl: react at 15-30℃ for 1-5 hours in a TFA-DCM system with a volume ratio of 1:(0.5-1.5).

[0058] According to some embodiments of the present invention, the compound represented by Formula 3, or a pharmaceutically acceptable salt or hydrate thereof, is prepared by a method comprising the following steps:

[0059]

[0060] (a) The azide group of the compound represented by formula D4, or a pharmaceutically acceptable salt or hydrate thereof, is reduced to an amino group, and the resulting compound is then subjected to a nucleophilic substitution reaction with N,N'-di-Boc-1H-pyrazole-1-carboxamidine under basic conditions to give intermediate 1, or a pharmaceutically acceptable salt or hydrate thereof;

[0061] (b) Deacetyl protecting group is removed from the acetoxy group in intermediate 1 or its pharmaceutically acceptable salt or hydrate, and the resulting compound is then ketalized with 2,2-dimethoxypropane in the presence of a catalyst and a solvent to give intermediate 2 or its pharmaceutically acceptable salt or hydrate.

[0062] (c) When R' is methyl: intermediate 2, or its pharmaceutically acceptable salt or hydrate, is subjected to a nucleophilic substitution reaction with p-nitrophenyl chloroformate in the presence of a catalyst, solvent and basic auxiliaries to give the compound of Formula 3, or its pharmaceutically acceptable salt or hydrate; when R' is tert-butyl: intermediate 2, or its pharmaceutically acceptable salt or hydrate, is hydrolyzed under basic conditions, and the hydrolysis product is then reacted with 2-tert-butyl-1,3-diisopropylurea, and the resulting product is then subjected to a nucleophilic substitution reaction with p-nitrophenyl chloroformate in the presence of a catalyst, solvent and basic auxiliaries to give the compound of Formula 3, or its pharmaceutically acceptable salt or hydrate.

[0063] According to some embodiments of the present invention, in step (a), the reduction of the azide group to an amino group is carried out under the following conditions: in the presence of a solvent and a catalyst, H2 is introduced as a reducing agent, and the reaction is carried out at 15-30°C for 8-16 hours; preferably, the solvent is ethanol; preferably, the catalyst is Pd-CaCO3-Pb(OAc)2.

[0064] According to some embodiments of the present invention, in step (a), the nucleophilic substitution reaction is carried out under the following conditions: the obtained compound is reacted with N,N'-di-tert-butoxycarbonyl-1H-pyrazole-1-carboxamide at 15-30°C for 10-18 hours in the presence of a solvent and a basic auxiliary agent; preferably, the solvent is tetrahydrofuran; preferably, the basic auxiliary agent is triethanolamine.

[0065] According to some embodiments of the present invention, in step (b), the deacetyl protecting group is carried out under the following conditions: in a methanol-sodium methoxide system with a volume ratio of 7:(1-5), the reaction is carried out at 15-30°C for 0.1-1 hours.

[0066] According to some embodiments of the present invention, in step (b), the ketalization reaction is carried out under the following conditions: at 15-30°C for 4-8 hours.

[0067] According to some embodiments of the present invention, in step (b), the catalyst is p-toluenesulfonic acid and / or p-toluenesulfonic acid pyridinium salt, preferably p-toluenesulfonic acid pyridinium salt.

[0068] According to some embodiments of the present invention, in step (b), the solvent is dichloromethane and / or acetone, preferably dichloromethane.

[0069] According to some embodiments of the present invention, in step (c), when R' is methyl or tert-butyl, the nucleophilic substitution reaction is carried out under the following conditions: at 15-30°C for 10-18 hours.

[0070] According to some embodiments of the present invention, in step (c), when R' is methyl or tert-butyl, the catalyst is 4-dimethylaminopyridine.

[0071] According to some embodiments of the present invention, in step (c), when R' is methyl or tert-butyl, the solvent is dichloromethane and / or pyridine, preferably dichloromethane.

[0072] According to some embodiments of the present invention, in step (c), when R' is methyl or tert-butyl, the basic auxiliary is diisopropylethylamine.

[0073] According to some embodiments of the present invention, in step (c), the hydrolysis is carried out under the following conditions: in the presence of an alkaline auxiliary agent and a solvent, the reaction is carried out at 15-30°C for 0.1-1 hours; preferably, the alkaline auxiliary agent is KOH; preferably, the solvent is dioxane-H2O in a volume ratio of 3:(0.5-1.5).

[0074] According to some embodiments of the present invention, in step (c), the hydrolysis product is reacted with 2-tert-butyl-1,3-diisopropylurea under the following conditions: in the presence of a solvent, the reaction is carried out at 15-30°C for 40-56 hours; preferably, the solvent is DCM.

[0075] Thirdly, the present invention provides a pharmaceutical composition for the prevention and / or treatment of influenza or related diseases, comprising a compound according to the first aspect of the present invention, or a pharmaceutically acceptable salt or hydrate thereof, or a compound prepared by the method according to the second aspect of the present invention, or a pharmaceutically acceptable salt or hydrate thereof.

[0076] According to some embodiments of the present invention, the pharmaceutical composition further comprises one or more pharmaceutically acceptable excipients.

[0077] According to some embodiments of the present invention, the influenza is influenza A.

[0078] Fourthly, the present invention provides the use of compounds according to the first aspect of the invention, or pharmaceutically acceptable salts or hydrates thereof, compounds prepared by the method according to the second aspect of the invention, or pharmaceutical compositions according to the third aspect of the invention, in the preparation of medicaments for the prevention and / or treatment of influenza or related diseases.

[0079] According to some embodiments of the present invention, the influenza is influenza A.

[0080] In specific embodiments of the present invention, the pharmaceutical compositions of the present invention may be administered via any suitable route. Suitable routes may include oral, rectal, nasal, aerosol or particulate inhalation, local (including sublingual and sublingual), transdermal, vaginal, intravesical, intra-wound, and parenteral (including subcutaneous, intramuscular, intravenous, intrasternal, intramembranous, epidural, and intradermal).

[0081] In specific embodiments of the invention, pharmaceutically acceptable excipients may be in the form of carriers, diluents, adjuvants, and / or excipients, and may include all conventional solvents, dispersants, fillers, solid carriers, coatings, antifungal or antimicrobial agents, skin penetrants, surfactants, isotoners, absorbents, and sustained-release or controlled-release matrices. Each carrier, diluent, adjuvant, and / or excipient must be "pharmaceutically acceptable" in the sense of compatibility with other components of the composition and patient physiological tolerability. The composition may be readily available in a single dosage form and may be prepared by methods known in the pharmaceutical industry. These methods include the step of mixing the active ingredient with a carrier, wherein the carrier is composed of one or more excipients. Generally, the preparation of the composition includes uniformly and directly mixing the active ingredient with a liquid carrier, diluent, adjuvant, and / or excipient or finely separated solid carrier or both, and then shaping the product if necessary.

[0082] The compositions of the present invention suitable for oral administration may be in the form of isolated units, such as capsules, sacs, or tablets, each containing a predetermined amount of the active ingredient; as powder or granules; as a solution or suspension in an aqueous or non-aqueous liquid; or as an oil-in-water emulsion or an oil-in-water emulsion. The active ingredient may also be in the form of pellets, syrups, or pastes.

[0083] Tablets can be prepared by compression or molding, optionally with one or more excipients. Compressed tablets can be prepared by pressing the active ingredient in a free-flowing form, such as powder or granules, in a suitable machine, optionally mixed with a binder (e.g., an inert diluent, preservative, disintegrant, starch, sodium glycolate, crospovidone, crospovidone), surfactant, or dispersant. Molded tablets can be prepared by molding a mixture of powdered compounds moistened with an inert liquid diluent in a suitable machine. Tablets can optionally be coated or scored to allow for sustained or controlled release of the active ingredient, for example, by using varying proportions of hydroxypropyl methylcellulose to produce the desired release properties. Tablets may optionally have an enteric coating for release in the intestine rather than the stomach.

[0084] Compositions suitable for parenteral administration include aqueous and non-aqueous isotonic sterile injectable solutions, which may contain antioxidants, buffers, antibacterial agents, and solutes that make the composition isotonic with the blood of the intended patient; and aqueous and non-aqueous sterile suspensions, which may include suspending agents and thickeners. The compositions may be present in single-dose or multi-dose sealed containers such as ampoules and tubes, and may be stored under freeze-drying (lyophilization) conditions, requiring only the addition of a sterile liquid carrier, such as water for injection, prior to use. Injectable solutions and suspensions can be prepared from the aforementioned types of sterile powders, granules, and tablets.

[0085] Compositions suitable for topical application to the skin, i.e., transdermal application, can contain an active agent dissolved or suspended in any suitable carrier or matrix, and can be in the form of lotions, gels, creams, pastes, ointments, etc. Suitable carriers may include liquid paraffin, propylene glycol, waxes, polyoxyethylene, and long-chain alcohols. Transdermal devices such as patches can also be used, which may contain microporous membranes made of suitable materials such as nitric acid / cellulose acetate, propylene, and polycarbonate. Patches may also contain suitable skin adhesion and base materials.

[0086] The active compounds of the present invention can also be present in the form of implants, which may contain polymeric devices of the drug, wherein the polymer is biocompatible and non-toxic. Suitable polymers may include hydrogels, silicones, polyethylene, and biodegradable polymers.

[0087] The compounds of this invention can be administered in a sustained-release (i.e., controlled-release) or extended-release form. A sustained-release formulation is one in which the active ingredient is slowly released from the patient after administration and maintains the desired drug concentration for a minimal period of time. The preparation of sustained-release formulations is well known to those skilled in the art. Dosage forms may include oral, implantable, and transdermal forms. For extended-release administration, the active ingredient may be, for example, a sustained-release particle suspension or in liposomes.

[0088] The appropriate dosage range of the compounds of the present invention is selected based on the specific activity of the chosen compound, the patient's condition, and the disease to be treated. Those skilled in the art can determine the appropriate dosage range based on their general knowledge and experience in the field.

[0089] The present invention has at least the following beneficial effects:

[0090] This invention provides a novel dual-target drug by covalently linking molecules with anti-influenza inhibitory activity (M2 ion channel inhibitor and NA enzyme inhibitor).

[0091] Specifically, this invention covalently couples adamantane derivatives with zanamivir and its derivatives, so that the resulting covalent conjugate can improve the pharmacokinetic properties of zanamivir and also have dual target activity of M2 ion channel / NA enzyme inhibition. This can reduce or delay the risk of drug resistance to zanamivir and its derivatives, as well as adamantane and its derivatives, and has high inhibitory activity against drug-resistant mutant strains of influenza virus.

[0092] In vitro experiments showed that the covalent conjugate of the present invention has high safety and stronger anti-influenza virus activity compared to amantadine, oseltamivir, and zanamivir. In vivo experiments showed that the covalent conjugate of the present invention achieves better antiviral effects than zanamivir at lower concentrations, while also having higher safety. Attached Figure Description

[0093] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings, wherein:

[0094] Figure 1 This demonstrates the inhibitory effects of different compounds on influenza virus strains;

[0095] Figure 2 The inhibition rates of different compounds against influenza virus strains at different concentrations are shown.

[0096] Figure 3 This study demonstrates the toxicity of different compounds to MDCK cells at different concentrations.

[0097] Figure 4 This study demonstrated the safety and anti-influenza virus activity of different compounds at the animal level. Detailed Implementation

[0098] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0099] Unless otherwise specified, all experimental materials used in the following examples are commercially available products. Additionally, room temperature in the following examples generally refers to 20-25°C, and overnight reaction generally refers to 12-16 hours.

[0100] Example 1 Synthesis of zanamivir-amantadine covalent conjugates

[0101] 1. Synthesis of zanamivir carbonate intermediate

[0102] (1) Synthetic route of intermediate 3-1

[0103]

[0104] The specific synthesis steps are as follows:

[0105] (a) Starting from the azide-substituted zanamivir intermediate D4 (which can be synthesized from commercially available N-acetylneuraminic acid (Neu5Ac), see the literature Feng E, Shin WJ, Zhu X, et al. Structure-based design and synthesis of C-1 and C-4-modified analogs of zanamivir as neuraminidase inhibitors [J]. Journal of Medicinal Chemistry, 2013, 56(3): 671-684), the 4-azide group is reduced to an amino group by catalytic hydrogenation with a Lindra catalyst, and then undergoes a nucleophilic substitution reaction with N,N'-di-tert-butoxycarbonyl-1H-pyrazole-1-carboxamide under basic conditions to convert it into intermediate 1 with two tert-butoxycarbonyl (Boc) protected guanidine groups;

[0106] (b) After the acetoxy group in intermediate 1 is deacetylated in the methanol-sodium methoxide system, the exposed cis-vicinal diol at C8 and C9 positions reacts with 2,2-dimethoxypropane in dichloromethane solvent and is catalyzed by pyridinium p-toluenesulfonate (PPTS) to form a ketal structure. The C7 hydroxyl group that can undergo nucleophilic reaction is selectively retained to obtain intermediate 2. The yield of the two-step reaction is as high as 98%, and the conversion is basically quantitative.

[0107] (c) In the solvent dichloromethane and under the catalysis of DMAP and in the alkaline environment provided by diisopropylethylamine (DIEA), the exposed C7 hydroxyl group of intermediate 2 undergoes a nucleophilic substitution reaction with 4-nitrophenylchloroformate to generate an important and active 3-nitrophenyl carbonate intermediate, which can then undergo an amide condensation reaction with a compound having an amino functional group.

[0108] The reagents and conditions for the above reaction are as follows:

[0109] Step (a):

[0110] (i) Reduction of azide groups to amino groups: using ethanol (EtOH) as solvent, Pd-CaCO3-Pb(OAc)2 as catalyst, and H2 as reducing agent, the reaction was carried out at room temperature for 12 hours.

[0111] (ii) Nucleophilic substitution reaction: using tetrahydrofuran (THF) as solvent and triethanolamine (TEA) as basic auxiliary agent, the reactant N,N'-di-tert-butoxycarbonyl-1H-pyrazole-1-carboxamide was added and reacted overnight at room temperature; the yield of the above two steps was as high as 98%;

[0112] Step (b):

[0113] (i) Deacetyl protecting group: using methanol-sodium methoxide in a volume ratio of 7:3 as solvent, react at room temperature for 0.5 hours;

[0114] (ii) Ketation reaction: 2,2-dimethoxypropane was added as a reactant, and PPTS was used as a catalyst and DCM was used as a solvent. The reaction was carried out at room temperature for 6 hours.

[0115] Step (c):

[0116] Nucleophilic substitution reaction: Using DMAP as catalyst, DIEA as basic auxiliary agent, and DCM as solvent, p-nitrophenyl chloroformate was added to the reaction mixture and the reaction was carried out overnight at room temperature with a yield of 74%.

[0117] In the above-described route, this invention improves the synthetic route of the active intermediate of zanamivir carbonate by replacing the reaction solvent acetone in step (b) with dichloromethane and using the milder PPTS instead of p-toluenesulfonic acid, thereby avoiding the deprotection of the Boc group caused by an excessively acidic environment. Furthermore, this invention replaces the solvent pyridine in step (c) with dichloromethane and adds DIEA to increase the basicity of the reaction system, increasing the yield of this step from 59% to 74%.

[0118] (2) Synthetic route of intermediate 3-2

[0119] Alternatively, the methyl group in the methoxycarbonyl group of intermediate 3-1 can be replaced with a protecting group that can be removed under acidic conditions, such as a tert-butyl group, to achieve removal under TFA-DCM conditions. The synthetic route is as follows:

[0120]

[0121] The specific synthesis steps are as follows:

[0122] (a) Using intermediate 2 as a raw material, the protecting group is converted, and the methoxy carbonyl group therein is hydrolyzed under alkaline conditions;

[0123] (b) The product obtained after hydrolysis in step (a) is reacted with 2-tert-butyl-1,3-diisopropylisourea to generate intermediate 2';

[0124] (c) In the solvent dichloromethane and under the catalysis of 4-dimethylaminopyridine and in an alkaline environment provided by diisopropylethylamine, the exposed C7 hydroxyl group of intermediate 2' undergoes a nucleophilic substitution reaction with p-nitrophenyl chloroformate to generate acid-hydrolyzable zanamivir active intermediate 3-2.

[0125] The reagents and conditions for the above reaction are as follows:

[0126] Step (a): Using KOH as an alkaline auxiliary agent, react at room temperature for 30 min in a dioxane-H2O (volume / volume, 3:1) system;

[0127] Step (b): Using DCM as solvent, add reactant 2-tert-butyl-1,3-diisopropylurea and react at room temperature for 48 hours; the yield of the above two steps is 67%;

[0128] Step (c): Using DMAP as a catalyst, DIEA as an alkaline auxiliary agent, and DCM as a solvent, p-nitrophenyl chloroformate was added to the reaction mixture and allowed to react overnight at room temperature. The reaction yield was 61%.

[0129] 2. Synthesis of adamantaneamine compounds

[0130] Amantadine, rimantadine, and their analogues, including 3-hydroxyamantadine, 3-bromoamantadine, triazaspiro-[5.5]-undecane, cyclohexylmethylamine, cyclohexylamine, piperidine, and (1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]heptane-3-amine, were selected for the synthesis of this covalently coupled compound, the structures of which are shown below:

[0131]

[0132] 3-Bromoadamantaneamine requires the preparation of intermediate compound 18 from 3-bromo-1-adamantanecarboxylic acid via the Curtius rearrangement reaction, followed by deprotection of the Boc group under THF-DCM conditions. The synthetic route is as follows:

[0133]

[0134] The reagents and conditions are as follows:

[0135] Step (a):

[0136] (i) Using tert-butanol (t-BuOH) as solvent, 3-bromo-1-adamantane carboxylic acid, diphenyl azidophosphate (DPPA) and TEA were added and reacted at room temperature for 1 hour;

[0137] (ii) The reaction was continued under N2 protection and refluxed overnight, with a yield of 34%;

[0138] Step (b):

[0139] The reaction was carried out at room temperature for 0.5 hours in a TFA-DCM (volume / volume, 1:1) system.

[0140] The specific steps for synthesizing compound 18 are as follows:

[0141] 3-Bromo-1-adamantanecarboxylic acid (500 mg, 1.9 mmol), diphenyl azidophosphate (907 mg, 3.3 mmol), and triethylamine (802 μL, 5.8 mmol) were dissolved in tert-butanol (25 mL). After stirring at room temperature for 1 hour, the mixture was heated to reflux under nitrogen protection overnight. After the reaction was completed by TLC monitoring, the tert-butanol was evaporated to dryness, and the mixture was extracted with ethyl acetate (60 mL × 3) and deionized water (60 mL). The combined organic phases were washed successively with saturated sodium bicarbonate aqueous solution (60 mL × 3) and saturated brine (60 mL × 3). The resulting organic phases were dried over anhydrous sodium sulfate, filtered, and evaporated to dryness to obtain the crude product. Purification by silica gel column chromatography (eluent: polyethylene:ethyl acetate (PE:EtOAc) = 20:1) yielded 236 mg of a white solid, with a yield of 34%. f =0.68 (PE: EtOAc = 4: 1); 1 H NMR (400 MHz, CDCl3): δ 4.45 (brs, 1H), 2.54 (s,2H), 2.24 (s, 4H), 2.23 – 2.16 (m, 2H), 1.97 (d, J = 12.1 Hz, 2H), 1.82 (d, J= 11.9 Hz, 2H), 1.62 (brs, 2H), 1.41 (s, 9H); 13 C NMR (100 MHz, CDCl3): δ154.03, 79.28, 63.46, 53.27, 52.71, 48.01, 40.22, 34.54, 32.42, 28.54; ES-TOF-HRMS (m / z): C 15 H 23 BrNO2[M-H] - The calculated value is 328.0917, and the measured value is 328.0910.

[0142] 3. Synthesis of Zanamivir-Amantadine Covalent Conjugates

[0143] Nine zanamivir-amantadine covalent conjugates (20a-20i) were prepared, and the synthetic routes are shown below:

[0144]

[0145] The reagents and conditions are as follows:

[0146] Step (a):

[0147] Compounds 3-1, AH, and DMAP were dissolved in pyridine and coupled together at room temperature for 12 hours. The yields of compounds 19a, 19b, 19c, 19d, 19e, 19f, 19g, 19h, and 19i were 80%, 66%, 55%, 59%, 63%, 64%, 54%, 63%, and 76%, respectively.

[0148] Step (b) (removal of the methyl group from the ketal, tert-butyloxycarbonyl, and methoxycarbonyl groups):

[0149] (i) Using KOH as an alkaline auxiliary agent, the reaction was carried out at room temperature for 30 min in a dioxane-H2O (volume / volume, 3:1) system;

[0150] (ii) In the TFA-DCM (volume / volume, 1:1) system, the reaction was carried out at room temperature for 3 h;

[0151] The yields of 20a and 20e were both 80%, the yields of 20b, 20c, 20d, 20f, 20g and 20h were 98%, and the yield of 20i was 92%.

[0152] The specific steps for synthesizing compounds 19a-19i are as follows:

[0153] Synthesis of compound 19a

[0154] The mixture was coupled with adamantane (33 mg, 0.22 mmol), compound 3-1 (150 mg, 0.20 mmol), and DMAP (73 mg, 0.60 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: (CH3)2CO = 8:1→7:1→6:1) to give 122 mg of white solid. f = 0.65 (CH2Cl2: CH3OH = 10:1); 1HNMR (400 MHz, CDCl3): δ 11.38 (s, 1H), 8.42 (d, J = 8.4 Hz, 1H), 5.87 (s,1H), 5.75 (d, J = 8.1 Hz, 1H), 5.20 (t, J = 9.2 Hz, 1H), 5.16 (d, J = 6.2 Hz,1H), 4.71 (s, 1H), 4.40 – 4.27 (m, 2H), 4.24 – 4.13 (m, 1H), 4.12 – 4.05 (m,1H), 4.04 – 3.96 (m, 1H), 3.78 (s, 3H), 2.04 (s, 3H), 1.98 – 1.86 (m, 9H),1.63 (br s, 6H), 1.47 (s, 18H), 1.39 (s, 3H), 1.34 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ 170.60, 163.23, 162.08, 157.12, 152.85, 145.56, 109.96, 109.03,83.78, 79.68, 77.94, 74.93, 68.80, 66.05, 52.51, 50.94, 49.14, 48.44, 41.60,36.42, 29.57, 28.39, 28.20, 26.84, 25.62, 23.22; ESI-HRMS (m / z): C 37 H 58 N5O 12 [M + H] + The calculated value is 764.4076, and the measured value is 764.4076.

[0155] Synthesis of compound 19b

[0156] The mixture was coupled with rimantadine hydrochloride (47 mg, 0.22 mmol), compound 3-1 (150 mg, 0.20 mmol), and DMAP (73 mg, 0.60 mmol). The crude product was purified by silica gel column chromatography (eluent: PE: (CH3)2CO = 10:1 → 8:1 → 5:1) to give 117 mg of a white solid. f = 0.34 (PE: (CH3)2CO = 3: 1); 1H NMR (400 MHz, CDCl3): δ 11.37 (s, 1H), 8.48 – 8.30 (m, 1H), 5.97 – 5.81 (m, 2H), 5.42 – 5.13 (m, 2H), 4.96 – 4.58 (m, 1H), 4.56 – 4.27 (m, 2H), 4.19 – 3.83(m, 2H), 3.78 (s, 3H), 3.34 – 3.22 (m, 1H), 2.02 – 1.85 (m, 3H), 1.89 (s,3H), 1.71 – 1.32 (m, 36H), 1.11 – 0.97 (m, 3H); 13 C NMR (100 MHz, CDCl3): δ 170.71, 170.67, 163.29, 163.19, 162.15, 162.08, 157.09, 156.97, 155.57, 155.40, 152.95, 152.85, 145.55, 145.30, 110.27, 110.00, 109.07, 108.88, 83.76, 83.65, 79.63, 79.54, 77.87, 75.18, 74.55, 69.79, 69.50, 66.25, 66.04, 56.00, 56.80, 52.52, 52.48, 49.63, 49.06, 48.57, 48.36, 38.41, 38.33, 37.16,37.12, 36.04, 35.82, 28.40, 28.36, 28.17, 26.84, 26.74, 25.67, 25.55, 23.33,23.24, 14.77, 14.42; ESI-HRMS (m / z): C 39 H 62 N5O 12 [M + H] + The calculated value is 792.4389, and the measured value is 792.4397.

[0157] Synthesis of compound 19c

[0158] The mixture was coupled with 3-hydroxyadamantaneamine (20 mg, 0.12 mmol), compound 3-1 (90 mg, 0.12 mmol), and DMAP (44 mg, 0.36 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 50:1 → 30:1) to give 49 mg of a white solid. f = 0.60 (CH2Cl2: CH3OH = 9: 1); 1 HNMR (400 MHz, CDCl3): δ 11.34 (s, 1H), 8.39 (d, J = 8.4 Hz, 1H), 6.19 (d, J =9.1 Hz, 1H), 5.85 (s, 1H), 5.17 (d, J = 5.0 Hz, 1H), 5.13 (t, J = 8.8 Hz, 1H), 4.86 (s, 1H), 4.36 – 4.25 (m, 1H), 4.19 (q, J = 9.5 Hz, 1H), 4.07 (t, J = 7.4 Hz, 1H), 3.97 (t, J = 7.0 Hz, 1H), 3.75 (s, 3H), 2.55 (brs, 1H), 2.21(brs, 2H), 2.08 (s, 1H), 1.97 (d, J = 10.8 Hz, 1H), 1.87 (s, 3H), 1.86 – 1.74(m, 5H), 1.71 – 1.57 (m, 4H), 1.55 – 1.47 (m, 2H), 1.44 (s, 18H), 1.35 (s, 3H), 1.31 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ 170.63, 163.07, 162.01, 157.03,153.14, 152.75, 145.29, 110.12, 108.86, 83.74, 79.66, 77.91, 75.11, 69.26,68.76, 65.81, 53.39, 52.49, 49.22, 49.00, 47.94, 44.18, 43.94, 40.33, 40.05,34.87, 30.64, 28.32, 28.13, 26.74, 25.53, 23.15; ESI-HRMS (m / z): C 37 H 58 N5O 13[M+ H] + The calculated value is 780.4026, and the measured value is 780.4016.

[0159] Synthesis of compound 19d

[0160] Compound 18 (44 mg, 0.13 mmol), after deprotection with the Boc group, was coupled with compound 3-1 (100 mg, 0.13 mmol) and DMAP (49 mg, 0.40 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: (CH3)2CO = 20:1 → 18:1) to give 66 mg of white solid. f = 0.39 (PE: EtOAc= 1: 1); 1 H NMR (400 MHz, CDCl3): δ 11.39 (s, 1H), 8.44 (d, J = 8.6 Hz, 1H), 5.87 (d, J = 2.3 Hz, 1H), 5.83 (d, J = 8.2 Hz), 5.22 – 5.13 (m, 2H), 4.80 (s,1H), 4.34 (q, J = 6.1 Hz, 1H), 4.31 – 4.18 (m, 2H), 4.15 – 4.05 (m, 1H), 4.04– 3.96 (m, 1H), 3.79 (s, 3H), 2.64 (d, J = 11.7 Hz, 1H), 2.51 (d, J = 11.7Hz, 1H), 2.29 – 2.16 (m, 6H), 2.03 – 1.94 (m, 2H), 1.91 (s, 3H), 1.90 – 1.75(m, 2H), 1.61 (s, 2H) 1.48 (s, 18H), 1.40 (s, 3H), 1.35 (s, 3H); 13C NMR (100MHz, CDCl3): δ 170.64, 163.15, 161.98, 157.13, 152.82, 145.57, 109.92,109.02, 83.82, 79.70, 78.01, 74.89, 68.99, 65.95, 63.38, 52.54, 52.15, 49.17,48.37, 47.98, 47.89, 39.89, 39.67, 34.44, 32.41, 28.36, 28.18, 26.83, 25.56,23.18; ESI-HRMS (m / z): C 37 H 57 BrN5O 12 [M + H] + The calculated value is 842.3182, and the measured value is 842.3181.

[0161] Synthesis of compound 19e

[0162] The mixture was coupled with triazaspiro-[5,5]-undecane hydrochloride (20 mg, 0.11 mmol), compound 3-1 (79 mg, 0.12 mmol), and DMAP (39 mg, 0.32 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 50:1) to give 49 mg of a white solid. f = 0.64 (PE: EtOAc = 1:3); 1 H NMR (400 MHz, CDCl3): δ 11.37 (s, 1H), 8.38 (d, J = 8.5 Hz, 1H), 6.00 (d, J = 9.2 Hz, 1H), 5.86 (d, J = 2.3 Hz, 1H), 5.25 (dd, J = 5.5, 1.4 Hz,1H), 5.23 – 5.15 (m, 1H), 4.40 – 4.31 (m, 2H), 4.14 – 3.97 (m, 3H), 3.76 (s,3H), 3.58 – 3.42 (m, 2H), 3.33 (t, J = 10.9 Hz, 1H), 3.21 (t, J = 11.2 Hz,1H), 1.87 (s, 3H), 1.56 – 1.24 (m, 14H), 1.46 (s, 9H), 1.44 (s, 9H), 1.35 (s,3H), 1.32 (s, 3H);13 C NMR (100 MHz, CDCl3): δ 170.70, 163.20, 162.11, 156.99,154.66, 152.86, 145.37, 110.03, 108.86, 83.66, 79.56, 77.81, 75.08, 70.21,66.14, 52.42, 49.04, 48.56, 39.95, 37.87, 35.80, 35.71, 34.35, 31.12, 28.33,28.16, 26.82, 26.60, 25.47, 23.29, 21.51;ESI-HRMS (m / z): C 37 H 60 N5O 12 [M + H] + The calculated value is 766.4223, and the measured value is 766.4230. C 37 H 59 N5O 12 Na [M + Na] + The calculated value is 788.4052, and the measured value is 788.4044.

[0163] Synthesis of compound 19f

[0164] The mixture was coupled with cyclohexylmethylamine (11 mg, 0.097 mmol), compound 3-1 (73 mg, 0.097 mmol), and DMAP (36 mg, 0.29 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100: 1 → 50: 1) to give 45 mg of a white solid. f = 0.42 (PE: EtOAc = 1: 3); 1H NMR (400MHz, CDCl3): δ 11.37 (s, 1H), 8.41 (d, J = 8.7 Hz, 1H), 6.06 (d, J = 9.3 Hz, 1H), 5.87 (d, J = 2.4 Hz, 1H), 5.28 – 5.14 (m, 2H), 4.87 (t, J = 6.1 Hz, 1H),4.42 – 4.29 (m, 2H), 4.14 – 4.06 (m, 2H), 4.06 – 3.97 (m, 1H), 3.77 (s, 3H,),3.17 – 3.02 (m, 1H), 2.93 – 2.81 (m, 1H), 1.89 (s, 3H), 1.69 (d, J = 11.7 Hz,4H), 1.65 – 1.58 (m, 1H), 1.46 (s, 18H), 1.37 (s, 3H), 1.34 (s, 3H), 1.27 –1.06 (m, 4H), 0.88 (q, J = 11.5 Hz, 2H); 13 C NMR (100 MHz, CDCl3): δ 170.81,163.15, 162.10, 157.07, 155.80, 152.87, 145.33, 110.03, 109.02, 83.79, 79.70,77.62, 74.81, 69.77, 66.13, 52.50, 48.89, 48.51, 47.63, 38.13, 30.77, 28.35,28.16, 26.66, 26.50, 25.89, 25.55, 23.21; ESI-HRMS (m / z): C 34 H 56 N5O 12 [M + H] + The calculated value is 726.3920, and the measured value is 726.3908.

[0165] Synthesis of compound 19g

[0166] The mixture was coupled with cyclohexylamine hydrochloride (18 mg, 0.13 mmol), compound 3-1 (100 mg, 0.13 mmol), and DMAP (49 mg, 0.40 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 200:3) to give 51 mg of a white solid. f= 0.64 (PE: EtOAc = 1: 3); 1 H NMR (400MHz, CDCl3): δ 11.37 (s, 1H), 8.41 (d, J = 8.5 Hz, 1H), 6.00 (d, J = 9.3 Hz, 1H), 5.86 (d, J = 2.3 Hz, 1H), 5.31 – 5.06 (m, 2H), 4.74 (d, J = 7.9 Hz, 1H),4.39 – 4.27 (m, 2H), 4.17 – 4.04 (m, 2H), 4.04 – 3.97 (m, 1H), 3.76 (s, 3H),3.48 – 3.28 (m, 1H), 1.99 (d, J = 12.2 Hz, 1H), 1.89 (s, 3H), 1.88 – 1.82 (m,1H), 1.74 – 1.59 (m, 2H), 1.59 – 1.50 (m, 1H), 1.46 (s, 9H), 1.45 (s, 9H),1.36 (s, 3H), 1.33 (s, 3H), 1.31 – 1.22 (m, 2H), 1.19 – 1.01 (m, 3H); 13 C NMR (100 MHz, CDCl3): δ 170.75, 163.15, 162.05, 157.03, 154.65, 152.82, 145.35,109.97, 108.95, 83.75, 79.63, 77.64, 74.91, 69.51, 66.07, 52.51, 50.22,48.87, 48.49, 33.33, 33.04, 28.32, 28.14, 26.64, 25.58, 25.54, 24.90, 23.21;ESI-HRMS (m / z): C 33 H 54 N5O 12 [M + H] + The calculated value is 712.3764, and the measured value is 712.3773.

[0167] Synthesis of compound 19h

[0168] The mixture was coupled with piperidine (23 mg, 0.27 mmol), compound 3-1 (200 mg, 0.27 mmol), and DMAP (97 mg, 0.80 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 50:1) to give 116 mg of a white solid. f = 0.43 (PE: EtOAc = 1: 3); 1 H NMR (400 MHz, CDCl3): δ 11.39 (s, 1H), 8.40 (d, J = 8.6 Hz, 1H), 5.96 (d, J = 9.3 Hz, 1H), 5.87 (d, J = 2.4 Hz, 1H), 5.28 – 5.20 (m, 2H), 4.40 – 4.33 (m, 2H), 4.15 –4.09 (m, 1H), 4.09 – 4.00 (m, 2H), 3.78 (s, 3H), 3.62 – 3.42 (m, 2H), 3.41 –3.16 (m, 2H), 1.89 (s, 3H), 1.71 – 1.49 (m, 6H), 1.48 (s, 9H), 1.47 (s, 9H), 1.37 (s, 3H), 1.34 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ 170.79, 163.21,162.16, 157.08, 154.61, 152.93, 145.53, 109.97, 108.92, 83.79, 79.68, 77.87,75.02, 70.24, 66.23, 52.50, 48.98, 48.74, 45.13, 28.38, 28.22, 26.66, 25.55,24.46, 23.32; ESI-HRMS (m / z): C 32 H 52 N5O 12 [M + H] + The calculated value is 698.3607, and the measured value is 698.3599.

[0169] Synthesis of compound 19i

[0170] The mixture was coupled with (1R,2R,3R,5S)-2,6,6-trimethylbicyclo[3.1.1]heptane-3-amine (20 mg, 0.13 mmol), compound 3-1 (100 mg, 0.13 mmol), and DMAP (49 mg, 0.40 mmol). The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: (CH3)2CO: CH3OH = 25: 1: 0 → 100: 5: 1 → 50: 0: 1) to give 83 mg of white solid. f = 0.45 (PE: EtOAc = 1: 1); 1 H NMR (400 MHz, CDCl3): δ11.36 (s, 1H), 8.41 (d, J = 8.6 Hz, 1H), 5.87 (d, J = 2.4 Hz, 1H), 5.27 –5.16 (m, 2H), 4.76 (d, J = 8.8 Hz, 1H), 4.40 – 4.29 (m, 2H), 4.20 – 4.06 (m,2H), 4.06 – 3.99 (m, 1H), 3.97 – 3.85 (m, 1H), 3.77 (s, 3H), 2.60 – 2.47 (m,1H), 2.40 – 2.30 (m, 1H), 1.96 – 1.91 (m, 1H), 1.90 (s, 3H), 1.76 (t, J = 5.6Hz, 1H), 1.75 – 1.66 (m, 2H), 1.46 (s, 9H), 1.45 (s, 9H), 1.37 (s, 3H), 1.34(s, 3H), 1.18 (s, 3H), 1.06 (d, J = 7.1 Hz, 3H), 0.99 (s, 3H), 0.82 (d, J =9.8 Hz, 1H); 13C NMR (100 MHz, CDCl3): δ 170.79, 163.16, 162.05, 157.06,155.30, 152.84, 145.46, 110.03, 108.94, 83.77, 79.64, 77.77, 75.05, 69.59,66.03, 52.52, 50.23, 48.95, 48.59, 47.78, 46.26, 41.68, 38.48, 36.76, 35.35,28.35, 28.16, 26.67, 25.62, 23.44, 23.20, 20.77; ESI-HRMS (m / z): C 37 H 58 N5O 12 [M-H] - The calculated value is 764.4082, and the measured value is Found 764.4081, C. 37 H 59 N5O 12 Cl [M + Cl] - The calculated value is 800.3854, and the measured value is 800.3871.

[0171] The specific steps for synthesizing compounds 20a-20i are as follows:

[0172] Synthesis of compound 20a

[0173] Compound 19a (55 mg, 0.072 mmol) was deprotected to give 31 mg of a white solid with a melting point (mp) > 300 °C. 1H NMR (400 MHz, DMSO-d6): δ 7.99 (d, J = 9.1 Hz, 1H), 7.57(d, J = 7.4 Hz, 1H), 7.40 (br s, 3H), 6.88 (s, 1H), 5.62 (s, 1H), 4.79 (d, J= 9.4 Hz, 1H), 4.34 (d, J = 10.0 Hz, 1H), 4.28 (t, J = 7.3 Hz, 1H), 4.01 (q,J = 9.6 Hz, 1H), 3.82 (t, J = 9.4 Hz, 1H), 3.41 (d, J = 11.3 Hz, 1H), 3.29 –3.20 (m, 1H), 1.97 (s, 3H), 1.89 – 1.70 (m, 9H), 1.67 – 1.49 (m, 6H); 13 C NMR (100 MHz, DMSO-d6): δ 169.14, 162.90, 157.10, 153.24, 145.34, 108.06, 75.79,69.06, 68.37, 63.22, 51.23, 49.71, 46.12, 40.94, 36.09, 28.84, 22.62; ESI-HRMS (m / z): C 23 H 36 N5O8 [M + H] + The calculated value is 510.2558, and the measured value is 510.2563.

[0174] Synthesis of compound 20b

[0175] Compound 19b (32 mg, 0.040 mmol) was deprotected to give 21 mg of a white solid, mp 236–238 °C; 1H NMR (400 MHz, CD3OD): δ 5.93 – 5.85 (m, 1H), 5.02 – 4.94 (m, 1H), 4.64 – 4.56 (m, 1H), 4.49 – 4.39 (m, 1H), 4.27 – 4.16 (m, 1H), 4.06 – 3.97(m, 1H), 3.69 – 3.61 (m, 1H), 3.55 – 3.45 (m, 1H), 3.28 – 3.17 (m, 1H), 2.06– 1.89 (m, 6H), 1.77 – 1.48 (m, 12H), 1.35 – 1.28 (m, 1H), 1.08 – 1.00 (m,3H); 13 C NMR (100 MHz, CD3OD): δ 173.55, 173.47, 164.65, 158.88, 158.79, 157.87, 157.76, 146.72, 146.66, 108.94, 77.32, 77.25, 70.80, 70.53, 64.51,64.28, 57.21, 56.90, 52.89, 52.70, 47.92, 39.50, 39.41, 38.19, 37.42, 37.02,29.88, 22.78, 22.73, 14.78, 14.39; QTOF-HRMS (m / z): C 25 H 40 N5O8[M + H] + The calculated value is 538.2871, and the measured value is 538.2873.

[0176] Synthesis of compound 20c

[0177] Compound 19c (37 mg, 0.047 mmol) was deprotected to give 26 mg of a pale yellow solid, mp >300 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.88 (d, J = 2.4 Hz, 1H), 4.92 – 4.90 (m, 1H, overlapping with water peak), 4.55 (d, J = 9.6 Hz, 1H), 4.40 (d, J = 8.6 Hz, 1H), 4.21 (t, J = 9.5 Hz, 1H), 4.05 – 3.90 (m, 1H), 3.63 (dd, J = 11.9, 2.5 Hz, 1H), 3.49 (dd, J = 11.8, 6.0 Hz, 1H), 2.21 (brs, 2H), 1.96 (s, 3H), 1.94 – 1.76 (m, 6H), 1.65 (s, 4H), 1.55 (brs, 2H); 13 C NMR (100 MHz, CD3OD): δ 173.55, 164.70,158.90, 155.59, 146.77, 108.87, 77.32, 70.59, 69.85, 69.72, 64.38, 54.09,52.68, 49.57, 44.91, 41.29, 41.21, 36.07, 32.03, 22.75; ESI-HRMS (m / z):C 33 H 36 N5O9[M + H] + The calculated value is 526.2508, and the measured value is 526.2515.

[0178] Synthesis of compound 20d

[0179] Compound 19d (30 mg, 0.036 mmol) was deprotected to give 26 mg of a pale yellow solid, mp 197 – 198 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.89 (d, J = 2.4 Hz, 1H), 4.94 – 4.89 (m, 1H, overlapping with water peak), 4.55 (dd, J = 9.8, 1.8 Hz, 1H), 4.42 (d, J = 8.6, 2.1Hz, 1H), 4.20 (t, J = 9.4 Hz, 1H), 4.04 – 3.94 (m, 1H), 3.63 (dd, J = 11.7, 2.5 Hz, 1H), 3.49 (dd, J = 11.8, 6.0 Hz, 1H), 2.62 – 2.46 (m, 2H), 2.31– 2.15 (m, 6H), 2.03 – 1.93 (m, 2H), 1.96 (s, 3H), 1.93 – 1.78 (m, 2H), 1.66 (brs,2H); 13 C NMR (100 MHz, CD3OD): δ 173.46, 164.71, 158.88, 155.55, 146.73,109.02, 77.32, 70.50, 69.98, 64.36, 64.27, 54.31, 53.37, 52.77, 48.44, 40.67,40.62, 35.41, 33.76, 22.78; QTOF-HRMS (m / z): C 23 H 35 BrN5O8[M + H] + The calculated value is 588.1664, and the measured value is 588.1667.

[0180] Synthesis of compound 20e

[0181] Compound 19e (38 mg, 0.049 mmol) was deprotected to give 20 mg of a pale yellow solid, mp 153 – 155 °C; 1H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.6 Hz, 1H), 5.02 (dd, J= 9.0, 2.6 Hz, 1H), 4.55 (dd, J = 9.7, 2.6 Hz, 1H), 4.42 (dd, J = 8.8, 2.6Hz, 1H), 4.19 (t, J = 9.3 Hz, 1H), 4.07 – 3.96 (m, 1H), 3.61 (dd, J = 11.6,3.1 Hz, 1H), 3.48 (dd, J = 12.0, 5.7 Hz, 1H), 3.58 – 3.37 (m, 3H), 3.34 –3.28 (m, 1H, (overlapping with CD3OD peak), 1.94 (s, 3H), 1.63 – 1.31 (m, 14H); 13 C NMR (100MHz, CD3OD): δ 173.56, 164.77, 158.93, 156.40, 146.99, 109.17, 77.64, 71.70,70.44, 64.31, 52.52, 48.64, 40.92, 38.17, 36.68, 35.90, 32.17, 27.82, 22.78,22.45; ESI-HRMS (m / z): C 23 H 38 N5O8[M + H] + The calculated value is 512.2715, and the measured value is 512.2720.

[0182] Synthesis of compound 20f

[0183] Compound 19f (30 mg, 0.041 mmol) was deprotected to give 19 mg of a white solid, mp 149–150 °C; 1H NMR (400 MHz, DMSO-d6): δ 8.00 (d, J = 8.8 Hz, 1H), 7.59 (d, J =8.0 Hz, 1H), 7.43 (brs, 3H), 7.21 (t, J = 5.7 Hz, 1H), 5.62 (s, 1H), 4.82 (d,J = 9.0 Hz, 1H), 4.41 – 4.26 (m, 2H), 3.98 (q, J = 9.0 Hz, 1H), 3.81 (t, J =9.0 Hz, 1H), 3.40 (d, J = 10.2 Hz, 1H), 3.23 (dd, J = 10.8, 7.5 Hz, 1H), 2.85– 2.64 (m, 2H), 1.77 (s, 3H), 1.71 – 1.52 (m, 5H), 1.43 – 1.26 (m, 1H), 1.21 – 1.01 (m, 3H), 0.90 – 0.71 (m, 2H); 13 C NMR (100 MHz, DMSO-d6): δ 169.26,163.37, 157.17, 155.74, 146.15, 107.33, 75.73, 69.33, 69.10, 63.14, 51.02,46.88, 46.28, 37.45, 30.28, 26.14, 25.51, 25.46, 22.63; ESI-HRMS (m / z):C 20 H 34 N5O8[M + H] + The calculated value is 472.2402, and the measured value is 472.2401.

[0184] Synthesis of 20g of compound

[0185] 19 g (38 mg, 0.054 mmol) of the compound was deprotected to give 25 mg of a white solid, mp 230–232 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.88 (d, J = 2.4 Hz, 1H), 5.00 – 4.96 (m, 1H, overlapping with water peak), 4.57 (dd, J = 9.8, 2.0 Hz, 1H), 4.42 (dd, J = 8.7, 2.2 Hz, 1H), 4.18 (t, J = 9.4 Hz, 1H), 4.08 – 3.95 (m, 1H), 3.63 (dd, J = 11.8, 2.8 Hz, 1H), 3.49 (dd, J = 11.8, 6.0 Hz, 1H), 3.34 – 3.25 (m, 1H, overlapping with CD3OD peak), 1.96 (s, 3H), 1.97 – 1.81 (m, 2H), 1.73 (d, J = 11.5 Hz, 2H), 1.66 – 1.56 (m,1H), 1.39 – 1.24 (m, 3H), 1.23 – 1.15 (m, 2H); 13 C NMR (100 MHz, CD3OD): δ173.61, 164.73, 158.90, 158.84, 157.06, 146.62, 108.95, 77.19, 70.47, 64.34,52.45, 51.37, 34.12, 33.86, 26.63, 26.11, 22.71; ESI-HRMS (m / z): C 19 H 32 N5O8[M+ H] + The calculated value is 458.2246, and the measured value is 458.2248.

[0186] Synthesis of compound 20h

[0187] After deprotection of the compound at 19 h (116 mg, 0.17 mmol), 73 mg of a white solid was obtained, mp 242–243 °C. 1¹H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.3 Hz, 1H), 5.08 – 5.00 (m, 1H, overlapping with water peak), 4.57 (dd, J = 9.9, 2.0 Hz, 1H), 4.47 (dd, J = 8.8, 2.2 Hz, 1H), 4.18 (t, J = 9.4 Hz, 1H), 4.07 – 3.93 (m, 1H), 3.62 (dd, J = 12.2, 2.8 Hz, 1H), 3.49 (dd, J = 11.9, 5.6 Hz, 1H), 3.56 – 3.37 (m, 3H), 3.34 – 3.24 (m, 1H, (overlapping with CD3OD peak), 1.95 (s, 3H), 1.76 – 1.38 (m, 6H); 13 C NMR (100 MHz, CD3OD): δ 173.60, 164.76, 158.89, 156.18, 146.87, 109.32, 77.52, 71.65,70.43, 64.24, 52.43, 48.69, 46.07, 26.44, 25.28, 22.75; ESI-H RMS (m / z):C 18 H 30 N5O8[M + H] + The calculated value is 444.2089, and the measured value is 444.2097.

[0188] Synthesis of compound 20i

[0189] Compound 19i (55 mg, 0.072 mmol) was deprotected to give 34 mg of a white solid, mp 221–223 °C; 1H NMR (400 MHz, CD3OD): δ 5.89 (d, J = 2.2 Hz, 1H), 5.00 – 4.96 (m,1H, overlap), 4.57 (dd, J = 9.8, 2.0 Hz, 1H), 4.42 (dd, J = 8.8, 2.2 Hz, 1H), 4.20 (t, J = 9.2 Hz, 1H), 4.07 – 3.98 (m, 1H), 3.93 – 3.83 (m, 1H), 3.65 (dd,J = 11.8, 2.9 Hz, 1H), 3.51 (dd, J = 11.7, 6.2 Hz, 1H), 2.57 – 2.43 (m, 1H),2.43 – 2.33 (m, 1H), 1.96 (s, 3H), 1.94 – 1.82 (m, 2H), 1.78 (t, J = 6.0 Hz,1H), 1.68 (ddd, J = 14.1, 6.2, 1.8 Hz, 1H), 1.23 (s, 3H), 1.20 – 1.12 (m,1H), 1.09 (d, J = 7.2 Hz, 3H), 1.04 (s, 3H), 1.00 – 0.93 (m, 1H); 13 C NMR (100MHz, CD3OD): δ 173.60, 164.73, 158.87, 157.74, 146.69, 108.90, 77.21, 70.60, 70.56, 64.40, 52.55, 51.10, 49.00 (overlapping with CD3OD peak), 48.43, 46.44, 42.92, 39.59, 37.43, 35.68, 28.55, 23.79, 22.72, 21.18; ESI-HRMS (m / z): C 23 H 38 N5O8[M+ H] + The calculated value is 512.2715, and the measured value is 512.2715.

[0190] Example 2 Synthesis of zanamivir-adamantine covalent conjugates

[0191] 1. Synthesis of zanamivir carbonate intermediate

[0192] The synthesis method is the same as in Example 1.

[0193] 2. Synthesis of amino-functionalized adamantine derivatives

[0194] The synthesis of zanamivir-adamantine covalent conjugates first requires amino-functionalization of adamantine. As shown in the following synthetic route, adamantine-1-acid, 3-hydroxyadamantine-1-acid, and 3-bromoadamantine-1-acid are used to construct amide-linked amino-functionalized adamantine derivatives 17a, 17c, and 17e via the reaction of 1-hydroxybenzotriazole (HOBt) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDCI); or ester-linked amino-functionalized adamantine derivatives 17b, 17d, and 17f are constructed via the reaction of EDCI and DMAP.

[0195]

[0196] The reagents and conditions are as follows:

[0197] Step (a) (Preparation of 17a, 17c and 17e):

[0198] (i) At room temperature, 1-hydroxybenzotriazole (HOBt) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDCI) were reacted in tetrahydrofuran solvent for 0.5 hours at room temperature.

[0199] (ii) Using tetrahydrofuran as a solvent, add the reactant N-Boc-ethylenediamine ((CH3)3COCONHCH2CH2NH2) and the basic auxiliary agent diisopropylethylamine (DIEA), and react overnight at room temperature;

[0200] The yields of 17a, 17c, and 17e were 61%, 70%, and 70%, respectively.

[0201] Step (b) (Preparation of 17b, 17d, and 17f):

[0202] Using DCM as solvent, EDCI as condensing agent, and DMAP as catalyst, N-Boc-ethylenediamine was added to the reaction mixture, and the mixture was reacted overnight at room temperature. The yields of 17b, 17d, and 17f were 94%, 80%, and 65%, respectively.

[0203] The specific steps for synthesizing compounds 17a-17f are as follows:

[0204] Synthesis of compound 17a

[0205] Amide condensation was performed using 1-adamantanecarboxylic acid (100 mg, 0.56 mmol), N-Boc-ethylenediamine (98 mg, 0.61 mmol), HOBt (80 mg, 0.61 mmol), EDCI (117 mg, 0.61 mmol), and DIEA (291 μL, 1.7 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: EtOAc = 1:1) to give 109 mg of a white solid. f = 0.46 (EA); 1 H NMR (400 MHz, CDCl3): δ 6.35 (brs, 1H), 4.89 (brs, 1H), 3.41 – 3.16 (m, 4H), 2.03 (brs, 3H), 1.84 (d, J = 2.6 Hz, 6H), 1.78 – 1.65(m, 4H), 1.44 (s, 9H); 13 C NMR (100 MHz, CDCl3): δ 179.02, 157.30, 79.87,41.30, 40.66, 40.08, 39.33, 36.68, 28.53, 28.28; ESI-HRMS (m / z): C 18 H 30 N₂O₃Na[M + Na] + The calculated value is 345.2149, and the measured value is 345.2147. C 36 H 60 N4O6Na [2M + Na] + The calculated value is 667.4404, and the measured value is 667.4404.

[0206] Synthesis of compound 17b

[0207] Ester condensation was performed using 1-adamantanecarboxylic acid (100 mg, 0.56 mmol), N-Boc-ethanolamine (98 mg, 0.61 mmol), EDCI (159 mg, 0.83 mmol), and DMAP (203 mg, 1.7 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: EtOAc = 10:1 → 5:1) to obtain 169 mg of a colorless oil. f = 0.71(PE: EA = 1: 1); 1H NMR (400 MHz, CDCl3): δ 4.71 (brs, 1H), 4.10 (t, J = 5.3Hz, 2H), 3.38 (q, J = 5.2 Hz, 2H), 2.01 (brs, 2H), 1.88 (d, J = 2.6 Hz, 6H),1.77 – 1.65 (m, 6H), 1.44 (s, 9H); 13 C NMR (100 MHz, CDCl3): δ 177.76, 155.87,79.65, 63.38, 40.87, 39.92, 38.93, 36.58, 28.51, 28.01; ESI-HRMS (m / z): C 18 H 29 NO4Na [M + Na] + The calculated value is 346.1989, and the measured value is 346.1986. C 36 H 58 N₂O₈Na [2M + Na] + The calculated value is 669.4086, and the measured value is 669.4086.

[0208] Synthesis of compound 17c

[0209] Amide condensation was performed using 3-hydroxy-1-adamantanecarboxylic acid (100 mg, 0.51 mmol), N-Boc-ethylenediamine (90 mg, 0.56 mmol), HOBt (76 mg, 0.56 mmol), EDCI (107 mg, 0.56 mmol), and DIEA (267 μL, 1.5 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: (CH3)2CO = 1:1) to give 121 mg of a colorless oily liquid. f = 0.42 (PE: (CH3)2CO = 1: 2); 1 H NMR (400 MHz, CDCl3): δ6.59 (brs, 1H), 5.16 (brs, 1H), 3.48 – 3.11 (m, 4H), 2.28 (brs, 1H), 2.27 –2.20 (m, 2H), 1.79 (s, 2H), 1.72 (d, J = 2.4 Hz, 4H), 1.70 – 1.62 (m, 4H), 1.59 – 1.52 (m, 2H), 1.42 (s, 9H); 13C NMR (100 MHz, CDCl3): δ 177.60, 157.40,79.82, 68.47, 46.80, 44.32, 44.10, 41.38, 39.88, 38.11, 35.17, 30.45, 28.51;ESI-HRMS (m / z): C 18 H 30 N₂O₄Na [M + Na] + The calculated value is 361.2098, and the measured value is 361.2099. C 36 H 60 N4O8Na [2M + Na] + The calculated value is 699.4304, and the measured value is 699.4301.

[0210] Synthesis of compound 17d

[0211] Ester condensation was performed using 3-hydroxy-1-adamantanecarboxylic acid (100 mg, 0.51 mmol), N-Boc-ethanolamine (90 mg, 0.56 mmol), EDCI (146 mg, 0.77 mmol), and DMAP (187 mg, 1.5 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: (CH3)2CO = 10:1 → 5:1) to give 138 mg of a white solid. f = 0.28 (CH2Cl: (CH3)2CO = 5: 1); 1 H NMR (400 MHz, CDCl3): δ 4.75 (brs,1H), 4.10 (t, J = 5.3 Hz, 2H), 3.37 (q, J = 5.2 Hz, 2H), 2.29 – 2.20 (m, 2H), 1.87 – 1.65 (m, 11H), 1.57 (brs, 2H), 1.43 (s, 9H); 13 C NMR (100 MHz, CDCl3): δ 176.43, 155.86, 79.70, 68.34, 63.67, 46.29, 44.36, 44.17, 39.81, 37.75,35.05, 30.29, 28.49; ESI-HRMS (m / z): C 18 H 29 NO5Na [M + Na] + The calculated value is 362.1938, and the measured value is 362.1937. C 36 H58 N2O 10 Na [2M + Na] + The calculated value is 701.3984, and the measured value is 701.3981.

[0212] Synthesis of compound 17e

[0213] Amide condensation was performed using 3-bromo-1-adamantanecarboxylic acid (75 mg, 0.29 mmol), N-Boc-ethylenediamine (51 mg, 0.32 mmol), HOBt (43 mg, 0.32 mmol), EDCI (61 mg, 0.32 mmol), and DIEA (151 μL, 0.87 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: (CH3)2CO = 3:1) to give 81 mg of a white solid. f = 0.56 (PE: (CH3)2CO = 1: 1); 1 H NMR (400 MHz, CDCl3): δ 6.61 (brs,1H, NH), 4.97 (brs, 1H, NH), 3.49 – 3.14 (m, 4H, NCH2), 2.41 (s, 2H), 2.36 –2.24 (m, 4H), 2.24 – 2.18 (m, 2H), 1.45 (s, 9H); 13 C NMR (100 MHz, CDCl3): δ176.47, 157.62, 80.11, 64.22, 50.29, 48.30, 45.13, 41.95, 39.81, 37.51,34.66, 32.04, 28.55; ESI-HRMS (m / z): C 18 H 29 BrN₂O₃Na [M + Na] + The calculated value is 423.1254, and the measured value is 423.1242.

[0214] Synthesis of compound 17f

[0215] Ester condensation was performed using 3-bromo-1-adamantanecarboxylic acid (75 mg, 0.29 mmol), N-Boc-ethanolamine (51 mg, 0.32 mmol), EDCI (83 mg, 0.43 mmol), and DMAP (106 mg, 0.87 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: PE: EtOAc = 6: 1) to give 138 mg of a white solid.f = 0.46 (PE:(CH3)2CO = 2:1); 1 H NMR (400 MHz, CDCl3): δ 4.70 (brs, 1H), 4.12 (t, J = 5.3Hz, 2H), 3.39 (q, J = 5.3 Hz, 2H), 2.47 (s, 2H), 2.36 – 2.26 (m, 4H), 2.25 –2.16 (m, 4H), 1.88 (d, J = 2.8 Hz, 4H), 1.69 (q, J = 2.2 Hz, 2H), 1.45 (s,9H); 13 C NMR (100 MHz, CDCl3): δ 155.86, 79.79, 63.89, 63.65, 49.66, 48.20,45.07, 39.80, 37.22, 34.55, 31.79, 28.53; QTOF-HRMS (m / z): C 18 H 29 BrNO4Na [M +Na] + The calculated value is 424.1094, and the measured value is 424.1093. C 36 H 58 Br2N2O8Na [2M + Na] + The calculated value is 825.2296, and the measured value is 825.2314.

[0216] 3. Synthesis of Zanamivir-Adamantane Covalent Conjugates

[0217] The synthetic route for zanamivir-adamantine covalent conjugates is shown below. Similarly, after covalently coupling the above-mentioned zanamivir active intermediate 3 with amino-functionalized adamantine derivatives 17a-17f, group deprotection was performed under conditions (b) or (c) to obtain a total of 6 zanamivir-adamantine covalent conjugates 22a-22f.

[0218]

[0219] The reagents and conditions are as follows:

[0220] Step (a):

[0221] (i) Deprotection of the Boc group: Compound 17 was dissolved in a TFA-DCM (volume / volume, 1:1) system and reacted at room temperature for 30 min;

[0222] (ii) Coupling reaction: Using pyridine as solvent and DMAP as catalyst, the compound obtained after step (i) was coupled with compound 3 and the reaction was carried out overnight at room temperature;

[0223] Step (b) (21a, 21c and 21e: removal of ketal, Boc and R'):

[0224] (i) Using KOH as an alkaline auxiliary agent, the reaction was carried out at room temperature for 30 min in a dioxane-H2O (volume / volume, 3:1) system;

[0225] (ii) Dissolve the product obtained in step (i) in a TFA-DCM (volume / volume, 1:1) system and react at room temperature for 3 hours;

[0226] Step (c) (21b, 21d, and 21f: removal of ketal, Boc, and R'):

[0227] In the TFA-DCM (volume / volume, 1:1) system, the reaction was carried out at room temperature for 3 hours;

[0228] The yields of compounds 22a, 22b, 22c, 22d, 22e, and 22f were 96%, 96%, 98%, 97%, 83%, and 99%, respectively.

[0229] The specific steps for synthesizing compounds 21a-21f are as follows:

[0230] Synthesis of compound 21a

[0231] Compound 17a (54 mg, 0.17 mmol), after deprotection with a Boc group, was coupled with compound 3 (126 mg, 0.17 mmol) and DMAP (61 mg, 0.50 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 50:1) to give 114 mg of a white solid, with a yield of 82%. f = 0.43(PE: (CH3)2CO = 1: 1); 1H NMR (400 MHz, CDCl3): δ 11.38 (s, 1H), 8.38 (d, J =8.5 Hz, 1H), 7.39 (t, J = 5.5 Hz, 1H), 6.48 – 6.30 (m, 1H), 5.88 (d, J = 2.2Hz, 1H), 5.17 (d, J = 6.2 Hz, 1H), 5.13 (tt, J = 8.2, 2.4 Hz, 1H), 5.05 (t, J= 5.7 Hz, 1H), 4.33 (q, J = 6.2 Hz, 1H), 4.31 – 4.25 (m, 2H), 4.11 – 3.96 (m,2H), 3.78 (s, 3H), 3.52 – 3.41 (m, 1H), 3.32 – 3.14 (m, 2H), 3.14 – 3.03 (m,1H), 2.03 – 1.93 (m, 3H), 1.89 (s, 3H), 1.84 (d, J = 2.7 Hz, 6H), 1.69 (t, J= 3.2 Hz, 6H) 1.46 (s, 9H), 1.45 (s, 9H), 1.36 (s, 3H), 1.33 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ 179.03, 170.99, 163.08, 162.00, 157.16, 155.67, 152.79,145.49, 110.14, 109.09, 83.80, 79.82, 78.27, 74.56, 69.79, 66.11, 52.57,49.44, 47.79, 40.88, 40.62, 39.21, 38.02, 36.71, 28.33, 28.25, 28.06, 26.66,25.52, 23.24; ESI-HRMS (m / z): C 40 H 63 N6O 13 [M + H] + The calculated value is 835.4448, and the measured value is 835.4430.

[0232] Synthesis of compound 21b

[0233] Compound 17b (21 mg, 0.064 mmol), after deprotection with the Boc group, was coupled with compound 14b (51 mg, 0.064 mmol) and DMAP (23 mg, 0.19 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 80:1 → 60:1) to give 39 mg of a white solid, with a yield of 70%. f = 0.68 (PE: EtOAc = 1: 3); 1 H NMR (400 MHz, CDCl3): δ 11.40 (s, 1H), 8.39(d, J = 8.4 Hz, 1H), 5.95 (d, J = 9.0 Hz, 1H), 5.76 (t, J = 2.1 Hz, 1H), 5.28(d, J = 1.6 Hz, 1H), 5.25 (d, J = 4.6 Hz, 1H), 5.20 (t, J = 9.4 Hz, 1H), 5.03(t, J = 5.9 Hz, 1H), 4.43 – 4.24 (m, 2H), 4.22 – 3.96 (m, 4H), 3.51 – 3.38(m, 1H), 3.38 – 3.25 (m, 1H), 1.99 (brs, 3H), 1.89 (s, 3H), 1.86 (brs, 5H), 1.76 – 1.63 (m, 6H), 1.50 (s, 9H), 1.46 (s, 18H), 1.35 (s, 3H), 1.33 (s, 3H); 13 C NMR (100 MHz, CDCl3): δ 177.65, 170.87, 163.23, 160.53, 157.10, 155.70,152.84, 146.39, 108.85, 83.72, 82.46, 79.66, 77.59, 75.17, 69.97, 66.01,63.02, 53.54, 48.93, 48.66, 40.82, 40.64, 38.91, 36.55, 28.36, 28.16, 28.13,27.97, 26.57, 25.57, 23.22;ESI-HRMS (m / z): C 43 H 69 N5O 14 [M + H] +The calculated value is 878.4758, and the measured value is 878.4738.

[0234] Synthesis of compound 21c

[0235] Compound 17c (45 mg, 0.13 mmol), after deprotection with the Boc group, was coupled with compound 3 (100 mg, 0.13 mmol) and DMAP (49 mg, 0.40 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1→50:1→30:1→20:1) to give 68 mg of a white solid, with a yield of 60%. f = 0.32 (PE: (CH3)2CO = 1: 2); 1 H NMR (400 MHz, CDCl3): δ 11.39 (s, 1H), 8.31 (d, J = 8.4 Hz, 1H), 7.50 (t, J = 5.1 Hz, 1H), 6.56 (d, J = 8.5 Hz, 1H), 5.87 (d, J = 1.9 Hz, 1H), 5.83 (d, J = 8.2 Hz, 1H), 5.23 – 5.07 (m, 3H), 4.32(q, J = 6.0 Hz, 1H), 4.30 – 4.23 (m, 2H), 4.12 – 4.03 (m, 1H), 4.02 – 3.93(m, 1H), 3.76 (s, 3H), 3.52 – 3.39 (m, 1H), 3.31 – 3.00 (m, 3H), 2.72 (brs,1H), 2.20 (s, 2H), 1.89 (s, 3H), 1.85 – 1.67 (m, 6H), 1.63 (s, 4H), 1.57 –1.48 (m, 2H), 1.45 (s, 18H), 1.34 (s, 3H), 1.31 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 177.59, 171.10, 163.07, 161.98, 157.03, 155.73, 152.77, 145.30,110.29, 109.05, 83.82, 79.83, 78.19, 74.63, 69.72, 68.44, 65.95, 52.54,49.48, 47.53, 46.92, 44.38, 44.23, 44.14, 40.65, 38.07, 37.91, 35.20, 30.46,30.41, 28.31, 28.08, 26.61, 25.44, 23.26; ESI-HRMS (m / z): C 40 H 62 N6O 14 [M + H] + The calculated value is 851.4397, and the measured value is 851.4390.

[0236] Synthesis of compound 21d

[0237] Compound 17d (34 mg, 0.10 mmol), after deprotection with the Boc group, was coupled with compound 14b (80 mg, 0.10 mmol) and DMAP (37 mg, 0.30 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1→75:1→50:1→40:1) to give 57 mg of white solid, yield 63%. f = 0.60 (PE: (CH3)2CO = 1: 1); 1H NMR (400 MHz, CDCl3): δ 11.38 (s, 1H), 8.36 (d, J = 8.5 Hz, 1H), 6.15 (d, J = 9.2 Hz, 1H), 5.76 (d, J = 2.3 Hz, 1H), 5.24 (d, J = 4.4 Hz, 1H), 5.22 – 5.14 (m, 1H), 5.09 (t, J = 5.4 Hz, 1H), 4.39 – 4.25 (m, 2H), 4.21 – 3.97 (m, 5H), 3.50 – 3.23 (m, 2H), 2.23 (s, 2H), 2.03(brs, 1H), 1.86(s, 3H), 1.82 (s, 2H), 1.76 (brs, 4H), 1.67 (brs, 4H), 1.59 –1.53 (m, 2H), 1.49 (s, 9H), 1.46 (s, 9H), 1.45 (s, 9H), 1.34 (s, 3H), 1.32(s, 3H); 13 C NMR (100 MHz, CDCl3): δ 176.33, 170.89, 163.20, 160.53, 157.03,155.74, 152.82, 146.31, 108.91, 108.86, 83.72, 82.46, 79.67, 77.55, 75.20,69.99, 68.24, 65.92, 63.24, 48.94, 48.49, 46.34, 44.34, 44.30, 44.14, 40.53,37.72, 35.04, 30.26, 28.36, 28.16, 28.12, 26.57, 25.46, 23.19; ESI-HRMS (m / z): C 43 H 68 N5O 15 [M + H] + The calculated value is 894.4707, and the measured value is 894.4687.

[0238] Synthesis of compound 21e

[0239] Compound 17e (27 mg, 0.067 mmol), after deprotection with the Boc group, was coupled with compound 3 (50 mg, 0.067 mmol) and DMAP (24 mg, 0.20 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 50:1) to give 38 mg of a white solid, with a yield of 48%. f = 0.30(PE: EtOAc = 1: 3); 1 H NMR (400 MHz, CDCl3): δ 11.39 (s, 1H, NH), 8.40 (d, J =8.3 Hz, 1H, NH), 7.64 (t, J = 5.3 Hz, 1H), 6.32 (d, J = 9.0 Hz, 1H, NH), 5.87(d, J = 2.2 Hz, 1H), 5.21 – 5.07 (m, 2H), 4.90 (t, J = 5.4 Hz, 1H), 4.38 –4.22 (m, 3H), 4.12 – 4.05 (m, 1H), 4.05 – 3.98 (m, 1H), 3.78 (s, 3H), 3.55 –3.44 (m, 1H), 3.34 – 3.17 (m, 2H), 3.15 – 3.01 (m, 1H), 2.46 (s, 2H), 2.25 (d, J = 10.2 Hz, 2H), 2.21 – 2.13 (m, 2H), 1.92 (s, 3H), 1.91 – 1.79 (m, 4H),1.63 (brs, 2H), 1.47 (s, 18H), 1.37 (s, 3H), 1.34 (s, 3H); 13C NMR (100 MHz, CDCl3): δ 176.54, 171.33, 163.01, 161.94, 157.25, 155.67, 152.85, 145.77,109.78, 109.14, 83.89, 79.92, 78.42, 74.50, 69.94, 66.27, 64.65, 52.59,50.35, 49.53, 48.38, 48.27, 45.29, 40.77, 37.84, 37.44, 37.40, 34.77, 32.13,28.37, 28.16, 26.73, 25.56, 23.36; ESI-HRMS (m / z): C 40 H 62 BrN6O 13 [M + H] + The calculated value is 913.3553, and the measured value is 913.3546. C 40 H 61 BrN6NaO 13 [M + Na] + The calculated value is 935.3372, and the measured value is 935.3362.

[0240] Synthesis of compound 21f

[0241] Compound 17f (26 mg, 0.064 mmol), after deprotection with the Boc group, was coupled with compound 14b (51 mg, 0.064 mmol) and DMAP (23 mg, 0.19 mmol) as starting materials. The crude product was purified by silica gel column chromatography (eluent: CH2Cl2: CH3OH = 100:1 → 80:1 → 60:1) to give 42 mg of a white solid, with a yield of 69%. f = 0.55 (PE: EtOAc = 1: 3); 1H NMR (400 MHz, CDCl3): δ 11.39 (s, 1H), 8.39(d, J = 8.5 Hz, 1H), 5.91 (d, J = 9.2 Hz, 1H), 5.76 (d, J = 2.2 Hz, 1H), 5.87(d, J = 2.2 Hz, 1H), 5.23 (d, J = 4.6 Hz, 1H), 5.21 – 5.13 (m, 2H), 5.03 (t,J = 5.6 Hz, 1H), 4.34 (q, J = 6.2 Hz, 1H), 4.28 (dd, J = 10.5, 1.2 Hz, 1H),4.23 – 4.06 (m, 4H), 4.05 – 3.96 (m, 1H), 3.51 – 3.28 (m, 2H), 2.45 (s, 2H), 2.35 – 2.22 (m, 4H), 2.22 – 2.14 (m, 2H), 1.88 (s, 3H), 1.86 (d, J = 2.4 Hz, 4H), 1.67 (brs, 2H), 1.49 (s, 9H), 1.46 (s × 2, 18H), 1.35 (s, 3H), 1.33 (s,3H); 13 C NMR (100 MHz, CDCl3): δ 175.36, 170.78, 163.20, 160.49, 157.11,155.71, 152.82, 146.38, 108.85, 108.78, 83.73, 82.48, 79.66, 77.64, 75.12,70.00, 66.01, 63.59, 63.52, 49.62, 49.00, 48.49, 48.15, 45.00, 40.48, 37.18,34.51, 31.74, 28.35, 28.16, 28.13, 26.58, 25.52, 23.22; ESI-HRMS (m / z):C 43 H 67 BrN5O 14 [M + H] + The calculated value is 956.3863, and the measured value is 956.3852.

[0242] The specific steps for synthesizing compounds 22a-22f are as follows:

[0243] Synthesis of compound 22a

[0244] Compound 21a (76 mg, 0.091 mmol) was deprotected to give 56 mg of a white solid, mp > 300 °C; 1 ¹H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.4 Hz, 1H), 5.00 – 4.96 (m, 1H, overlap), 4.58 (dd, J = 9.7, 2.2 Hz, 1H), 4.49 (dd, J = 8.7, 2.2 Hz 1H), 4.19 (t, J = 9.2 Hz, 1H), 4.05 – 3.96 (m, 1H), 4.09 – 3.96 (m, 2H), 3.65 (dd, J = 11.8, 2.8 Hz, 1H), 3.51 (dd, J = 11.8, 5.8 Hz, 1H), 3.30 – 3.22 (m, 2H, overlap), 3.14 (t, J = 5.6 Hz, 1H), 2.01 (brs, 3H), 1.97 (s, 3H), 1.86 (d, J = 2.1Hz, 6H), 1.82 – 1.68 (m, 6H); 13 C NMR (100 MHz, CD3OD): δ 181.31, 173.61,164.69, 158.89, 158.19, 146.71, 109.00, 77.29, 71.04, 70.45, 64.33, 52.08,48.68, 41.78, 41.63, 40.10, 37.55, 29.57, 22.82; ESI-HRMS (m / z): C 26 H 41 N6O9[M+ H] + The calculated value is 581.2930, and the measured value is 581.2930.

[0245] Synthesis of compound 22b

[0246] Compound 21b (31 mg, 0.035 mmol) was deprotected to give 22 mg of a white solid, mp 236–238 °C; 1H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.4 Hz, 1H), 4.99 (dd, J = 9.1,2.3 Hz, 1H), 4.57 (dd, J = 9.7, 2.3 Hz, 1H), 4.42 (dd, J = 8.7, 2.5 Hz, 1H), 4.22 – 4.11 (m, 2H), 4.09 – 3.96 (m, 2H), 3.64 (dd, J = 11.8, 3.0 Hz, 1H), 3.50 (dd, J = 11.8, 6.4 Hz, 1H), 3.43 – 3.35 (m, 1H), 3.28 – 3.19 (m, 1H),2.00 (brs, 3H), 1.96 (s, 3H), 1.91 (d, J = 2.4 Hz, 6H), 1.76 (tt, J = 15.3,2.6 Hz, 6H); 13 C NMR (100 MHz, CD3OD): δ 179.22, 173.75, 164.69, 158.92,157.95, 146.70, 108.88, 77.29, 70.98, 70.44, 64.37, 63.99, 52.34, 48.48,41.97, 41.00, 39.90, 37.52, 29.39, 22.74; ESI-HRMS (m / z): C 26 H 40 N5O 10 [M + H] + The calculated value is 582.2770, and the measured value is 582.2772.

[0247] Synthesis of compound 22c

[0248] Compound 21c (45 mg, 0.053 mmol) was deprotected to give 32 mg of a white solid, mp > 300 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.4 Hz, 1H), 5.00 – 4.98 (m, 1H, overlapping with water peak), 4.57 (dd, J = 10.1, 1.9 Hz, 1H), 4.50 (dd, J = 9.0, 2.3 Hz 1H), 4.21 (t, J = 9.5 Hz, 1H), 4.06 – 3.98 (m, 1H), 3.64 (dd, J = 11.9, 2.8 Hz, 1H), 3.51 (dd, J = 11.9, 5.9 Hz, 1H), 3.40 – 3.35 (m, 1H, overlapping with CD3OD peak), 3.28 – 3.03 (m, 3H). 2.23 (s, 2H), 1.97 (s, 3H, Ac), 1.94 – 1.68 (m, 10H), 1.62 (s, 2H); 13 C NMR (100 MHz, CD3OD): δ 179.92, 173.42, 164.70, 158.95,158.05, 146.86, 109.11, 77.36, 70.96, 70.35, 69.42, 64.31, 52.36, 48.65,46.84, 45.31, 45.12, 45.07, 41.40, 39.50, 39.24, 38.86, 36.12, 31.82, 31.72,22.88; ESI-HRMS (m / z): C 26 H 41 N6O 10 [M + H] + The calculated value is 597.2879, and the measured value is 597.2889.

[0249] Synthesis of compound 22d

[0250] Compound 21d (38 mg, 0.043 mmol) was deprotected to give 28 mg of a white solid, mp 198–200 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.5 Hz, 1H), 5.00 (dd, J = 9.2, 2.3 Hz, 1H, overlap), 4.57 (dd, J = 8.8, 2.5 Hz, 1H), 4.43 (dd, J = 8.7, 2.2 Hz, 1H), 4.21 – 4.13 (m, 2H), 4.10 – 3.98 (m, 2H), 3.65 (dd, J = 11.8, 3.0 Hz, 1H), 3.51 (dd, J = 11.8, 6.2 Hz, 1H), 3.43 – 3.36 (m, 1H, overlap), 3.28 – 3.20 (m, 1H). 2.22 (brs, 2H), 1.96 (s, 3H, Ac), 1.87 – 1.75 (m, 6H), 1.70 (d, J =2.4 Hz, 4H), 1.62 (q, J = 2.4 Hz, 2H); 13 C NMR (100 MHz, CD3OD): δ 178.04, 173.71, 164.67, 158.92, 157.93, 146.71, 108.93, 77.28, 70.98, 70.44, 68.77, 64.36, 64.15, 52.34, 48.51 (overlap), 46.92, 45.21, 44.97, 41.00, 38.79, 36.10, 31.62, 22.74; ESI-HRMS (m / z): C 26 H 40 N5O 11 [M + H] + The calculated value is 598.2719, and the measured value is 598.2722.

[0251] Synthesis of compound 22e

[0252] Compound 21e (29 mg, 0.031 mmol) was deprotected to give 17 mg of a white solid, yield 83%, mp 181 – 182 °C; 1¹H NMR (400 MHz, CD3OD): δ 5.90 (d, J = 2.1 Hz, 1H), 4.99 (dd, J = 8.9, 1.8 Hz, 1H), 4.58 (dd, J = 9.7, 2.0 Hz, 1H), 4.47 (dd, J = 8.4, 1.6 Hz, 1H), 4.20 (t, J = 9.1 Hz, 1H), 3.65 (dd, J = 11.8, 2.6 Hz, 1H), 3.62 –3.55 (m, 1H), 3.52 (dd, J = 11.8, 5.6 Hz, 1H), 3.38 – 3.21 (m, 2H, overlapping with CD3OD peak), 3.14 (t, J = 5.0 Hz). Hz, 2H), 2.49 – 2.37 (m, 2H), 2.37 – 2.26 (m, 4H), 2.20 (brs, 2H), 1.97 (s, 3H), 1.87 (brs, 4H), 1.79 – 1.66 (m, 2H); 13 C NMR (100 MHz, CD3OD): δ 178.94, 173.63, 164.74, 158.91, 158.20, 146.81, 108.89,77.35, 71.05, 70.46, 65.07, 64.33, 52.17, 51.22, 49.35, 48.67, 46.36, 41.54,40.17, 38.39, 38.31, 35.49, 33.42, 22.84; ESI-HRMS (m / z): C 26 H 40 BrN6O9[M + H] + The calculated value is 659.2035, and the measured value is 659.2040.

[0253] Synthesis of compound 22f

[0254] Compound 21f (38 mg, 0.043 mmol) was deprotected to give 28 mg of a white solid, 99% yield, mp 172 – 173 °C; 1H NMR (400 MHz, DMSO-d6): δ 8.00 (d, J = 9.2 Hz, 1H), 7.64 (d, J= 8.8 Hz, 1H), 7.43 (t, J = 5.6 Hz, 1H), 7.31 (brs, 3H), 5.70 (d, J = 2.2 Hz,1H), 4.82 (dd, J = 9.3, 1.6 Hz, 1H), 4.37 (dd, J = 10.1, 1.8 Hz, 1H), 4.32(dd, J = 9.0, 1.9 Hz, 1H), 4.11 – 4.01 (m, 1H), 4.01 – 3.87 (m, 2H), 3.87 –3.77 (m, 1H), 3.41 (dd, J = 11.4, 2.5 Hz, 1H), 3.30 – 3.13 (m, 2H), 3.13 –3.03 (m, 1H), 2.41 (s, 2H), 2.26 (brs, 4H), 2.14 (brs, 2H), 1.81 (d, J = 1.6Hz, 4H), 1.78 (s, 3H), 1.71 – 1.57 (m, 2H); 13 C NMR (100 MHz, DMSO-d6): δ174.57, 169.39, 162.63, 157.07, 155.61, 144.90, 108.45, 75.81, 69.53, 68.88,66.20, 63.15, 62.91, 50.69, 49.14, 47.66, 46.14, 44.53, 36.40, 33.70, 31.36,22.65; ESI-HRMS (m / z): C 26 H 39 BrN5O 10 [M + H] + The calculated value is 660.1875, and the measured value is 660.1874.

[0255] Bioactivity evaluation

[0256] The anti-influenza virus activity of the zanamivir-adamantine covalent conjugates prepared in the above examples was evaluated, mainly including the inhibitory activity against multiple and mutant NA enzymes, the toxicity to MDCK cells, and the evaluation of anti-influenza activity at the cellular and animal levels.

[0257] 1. Experimental Materials

[0258] 1.1 Cells and Culture Methods

[0259] MDCK cells were purchased from the Cell Bank of the Chinese Academy of Sciences. The provider guaranteed that the cells were free of contamination. The cells were cultured at 37°C and 5% CO2 in DMEM (Gibco) medium containing 10% (v / v) fetal bovine serum (FBS, Gibco) and 1 μg / mL puromycin (Beijing leagenebiotech, Cat. CA0070).

[0260] 1.2 Influenza virus rescue

[0261] Influenza virus rescue was performed using an influenza virus 12-plasmid packaging system.

[0262] 2. Bioactivity test

[0263] 2.1 Neuraminidase (NA) Inhibition Test

[0264] The activity of various and mutant neuraminidases was detected using (4-methylumbelliferyl-aDN-acetylneuraminic acid sodium salt hydrate solution (MUNANA) as a substrate. The influenza virus NA protein can hydrolyze the MUNANA substrate and produce fluorescence.

[0265] The reaction system consisted of a series of analyte compounds at different concentrations, neuraminidase expressed and purified from insect cells, and 20 μM 4-MUNANA. The reaction solution was a 32.5 mM 2-morpholinoethanesulfonic acid (MES) solution (containing 4 mM CaCl2, pH = 6.5). The reaction was carried out in 96-well plates. After incubation at 37°C for 30 minutes, the reaction was terminated by adding 150 μL of 34 mM NaOH aqueous solution. Fluorescence readings were detected at an excitation wavelength of 360 nm and an emission wavelength of 460 nm.

[0266] 2.2 Surface Plasmon Resonance Experiment (SPR)

[0267] The binding mechanics of the test compound and the target protein were measured using the Biacore T200 system (GE Healthcare), and the binding force data between the test compound and the protein were calculated.

[0268] The specific steps are as follows: First, the recombinant viral protein was coupled to the CM5 chip using the amino-coupling method. This experiment was performed at 25°C. Following the instructions in the Biacore T200 manual, the final coupling amount of protein was determined based on its specific molecular weight. Next, the analyte was flowed through the chip at different concentrations using PBS-P (10 mM phosphate buffer containing 2.7 mM KCl, 137 mM NaCl, and 0.05% Surfactant P20, pH 4.5). For the binding experiment, the analyte flow rate was 30 µL / min, the binding time was 60 s, and the dissociation time was 60 s. The chip was then washed with the system buffer and additionally washed with 50% (v / v) DMSO. Finally, curve simulation was performed using Biacore evaluation software (T200 Version 1.0) in a 1:1 binding mode.

[0269] 2.3 Assay of anti-influenza activity at the MDCK cell level

[0270] Co-incubation of test solutions with cells: Discard the culture medium for MDCK cells, and add 100 μL of the test compound solution containing the virus (test compound experimental group), 1% (v / v) DMSO aqueous solution containing the virus (DMSO experimental group), the test compound solution without the virus (test compound control group), and 1% DMSO aqueous solution without the virus (DMSO control group) to the wells of MDCK cells, with three replicates for each group. The cells were then placed in a constant temperature incubator and cultured at 37℃ and 5% CO2 for 48 h. The inhibition rate was calculated by measuring cell viability.

[0271] Note: Cell viability in the DMSO control group was 100%.

[0272] Inhibition rate = [1 - (cell viability of experimental group of test compound - cell viability of control group of test compound) / (cell viability of experimental group of DMSO - cell viability of control group of DMSO)] × 100%.

[0273] 2.4 MDCK Cytotoxicity Assay

[0274] Co-incubation of test solutions with cells: Discard the culture medium for MDCK cells, and add 100 μL of the three concentrations of test compound solutions to the wells of MDCK cells, with three parallel experiments per group. Then place them in an incubator and incubate at 37°C and 5% CO2 for 48 h.

[0275] Assessing cell viability: Thawing CellTiter-Glo ®Buffer, equilibrate to room temperature, and simultaneously add CellTiter-Glo ® Equilibrate the lyophilized substrate powder to room temperature. Take 100 mL of CellTiter-Glo ® Buffer transferred to CellTiter-Glo ® In a brown bottle containing the substrate, rehydrate the lyophilized enzyme / substrate mixture by gently vortexing, rotating, or inverting the contents to mix thoroughly and obtain a homogeneous CellTiter-Glo ® Reagents. Add 40 μL of the reagent to the wells of cells incubated for 48 h, and mix using a shaker for 2 min to induce cell lysis. Then incubate the plate at room temperature for 10 min to stabilize the luminescence signal. Turn on the microplate reader beforehand, double-click the Shaking option under the Action section, then double-click the luminescence option under the Detection section to record the luminescence signal. Higher cell viability indicates lower cytotoxicity of the compound.

[0276] Note: Cell viability was calculated with the control group as 100%.

[0277] Cell viability in the experimental group = (fluorescence value of the experimental group / fluorescence value of the control group) × 100%;

[0278] The control group consisted of cells treated with DMSO only.

[0279] 2.5 Evaluation of safety and anti-influenza virus activity at the animal level

[0280] This invention evaluated the safety and anti-influenza virus activity at the animal level. Mice inoculated with 5×LD50 influenza virus (WSN) were administered the drug via intranasal drops once daily for five days. An experimental group (22a), a positive control group (ZNV), and a negative control group (PBS) were established, using two different drug concentrations (see [link to relevant documentation]). Figure 4 Mice were monitored for their living conditions and weight for fourteen consecutive days, and were considered dead when their weight dropped to 80%.

[0281] 3. Experimental Results

[0282] 3.1 Neuraminidase inhibition IC50

[0283] Table 1. Results of neuraminidase inhibition IC50

[0284]

[0285] A lower IC50 value indicates that a 50% inhibitory effect can be achieved at a lower compound concentration, suggesting a stronger inhibitory ability of the compound against neuraminidase and higher anti-influenza activity. The results show that compound 22a exhibits significantly higher inhibitory abilities against neuraminidase N1 (H275Y), N2, N9 (R292K), IBV-NA, and IBV-NA (E119V) than drugs OSV and ZNV. Its inhibitory abilities against neuraminidase N2 (E119V) and N9 are comparable to ZNV but higher than OSV.

[0286] 3.2 Affinity (SPR) of Neuraminidase to Compounds

[0287] Table 2. Affinity results of neuraminidase and compounds.

[0288]

[0289] The affinity between neuraminidase and a compound refers to the strength of the binding between the compound molecule and the neuraminidase. Higher affinity indicates a tighter binding between the compound and the neuraminidase, generally implying a stronger inhibitory effect. SPR (Spectroradioactive Protease) can directly measure the binding ability of a compound to neuraminidase, usually expressed as the dissociation constant (KD). The smaller the KD, the stronger the affinity. The results above show that, compared to drugs OSV and ZNV, compound 22a has a stronger affinity for neuraminidases N1 (H275Y), N2 (E119V), N9, N9 (R292K), IBV-NA, and IBV-NA (E119V). Its affinity for neuraminidase N2 is comparable to ZNV but higher than OSV.

[0290] 3.3 Results of the compound's antiviral activity against influenza virus strains

[0291] Figure 1 The inhibitory effects of compounds 22a, ZNV, OSV, and Aman on influenza virus strains A / WSN / 1933 (H1N1) (WSN), A / Puerto Rico / 8 / 34 (H1N1) (PR8), and A / Darwin / 9 / 2021 (H3N2) (H3N2) were demonstrated. Figure 1 It is evident that compound 22a exhibits better inhibitory activity, achieving significant viral inhibition at relatively low concentrations. This suggests that compound 22a possesses higher anti-influenza virus efficacy compared to ZNV, OSV, and Aman.

[0292] Table 3. EC50 (nM) results of the compounds against influenza virus strains

[0293]

[0294] EC50 refers to the concentration of a compound required to reduce the replication or infection rate of influenza virus by 50% in in vitro experiments. 50 The lower the value, the more effective the compound is at a lower concentration, indicating that it can achieve a 50% inhibitory effect on influenza virus and has higher antiviral activity.

[0295] The EC50 results of compounds 22a, ZNV, OSV, and Aman against three influenza virus strains are shown in the table above. The results indicate that, compared to ZNV, OSV, and Aman, compound 22a has significantly lower EC50 values ​​against influenza virus strains WSN, PR8, and H3N2, suggesting that compound 22a possesses stronger anti-influenza virus activity.

[0296] The inhibition rates of different compounds against WSN were tested according to the method described in Part 2.3 above, and the results are as follows: Figure 2 As shown in the figure, compound 22a (5 μM) exhibited higher anti-influenza virus activity compared to ZNV (5 μM), Aman (5 μM), and ZNV (5 μM) + Aman (5 μM); similarly, compound 22a (25 μM) also exhibited higher anti-influenza virus activity compared to ZNV (25 μM), Aman (25 μM), and ZNV (25 μM) + Aman (25 μM).

[0297] 3.4 Results of screening for anti-influenza virus activity of compounds

[0298] Cell viability generally refers to the ability of cells to survive and proliferate under specific conditions. In cytotoxicity experiments, the results of cell viability measurements can reflect the effect of a compound on cells. If the cell viability of cells treated with a compound does not decrease significantly compared to the untreated control group, or the decrease is small, this usually means that the compound has low cytotoxicity.

[0299] The toxicity of different compounds to MDCK cells, such as Figure 3 As shown (higher cytotoxicity corresponds to lower cell viability). Generally, the inhibitory effect of a drug on a virus is directly proportional to its cytotoxicity; that is, better viral inhibition is often accompanied by higher cytotoxicity. However, compound 22a exhibited superior anti-influenza virus activity while maintaining similar cytotoxicity to ZNV (see experimental results in Section 3.3). This indicates that compound 22a significantly enhanced the inhibitory effect on influenza virus while maintaining cell viability, achieving the dual goal of improving antiviral efficacy while ensuring cell safety.

[0300] 3.5 Results of safety and anti-influenza virus activity evaluation at the animal level

[0301] like Figure 4As shown, at higher concentrations, compound 22a exhibits safety and anti-influenza virus activity comparable to ZNV. However, surprisingly, at lower concentrations, compound 22a significantly surpasses ZNV in both safety and anti-influenza virus activity. In other words, compound 22a achieves superior antiviral efficacy and higher safety than ZNV at lower concentrations, providing significant competitiveness and application potential for compound 22a in the development of anti-influenza drugs.

[0302] The above descriptions are merely several exemplary embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any equivalent or similar implementation schemes obtained by those skilled in the art by making some modifications or alterations to the above-disclosed technical content without departing from the scope of the present invention are within the scope of the present invention.

Claims

1. A compound represented by Formula I, or a pharmaceutically acceptable salt or hydrate thereof, in, R1 is selected from -NHR5, -NH3 + Y – -NR5(C=NH)NH2 and -NR5(C=NH2)NH2 + )NH2Y – R5 is selected from H, unsubstituted C1-C6 straight-chain or branched alkyl groups, C1-C6 straight-chain or branched alkyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkenyl groups, C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkynyl groups, and C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl groups. C2-C6 straight-chain or branched alkynyl groups substituted with hydroxyl or carboxyl groups; unsubstituted C1-C6 straight-chain or branched alkoxy groups; C1-C6 straight-chain or branched alkoxy groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; unsubstituted aromatic groups; aromatic groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; unsubstituted aralkyl groups; aralkyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; wherein, Y – It is a negative counterion; R2 is an unsubstituted C1-C6 straight-chain or branched alkyl group or a C1-C6 straight-chain or branched alkyl group substituted with a halogen; R3 and R4 are each independently selected from H, unsubstituted C1-C6 straight-chain or branched alkyl, C1-C6 straight-chain or branched alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkenyl, C2-C6 straight-chain or branched alkenyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkynyl, and C2-C6 straight-chain or branched alkynyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl. A is selected from , , , , and ; R6 and R 16 Each is independently selected from H, halogen, hydroxyl, unsubstituted C1-C6 straight-chain or branched alkyl, C1-C6 straight-chain or branched alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkenyl, C2-C6 straight-chain or branched alkenyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkynyl, and C2-C6 straight-chain or branched alkynyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl. R7 and R 11 Each is independently selected from the following: unsubstituted C1-C6 straight-chain or branched alkylene groups, C1-C6 straight-chain or branched alkylene groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkenyl groups, and C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; R8, R9, R 10 and R 12 Each of the following groups is independently selected from unsubstituted C1-C6 straight-chain or branched alkyl groups, C1-C6 straight-chain or branched alkyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkenyl groups, C2-C6 straight-chain or branched alkenyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted C2-C6 straight-chain or branched alkynyl groups, and C2-C6 straight-chain or branched alkynyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; wherein n1 and n4 are each independently selected from integers from 0 to 10; n2 is selected from integers from 0 to 8; and n3 is selected from integers from 0 to 11. R 13 R 14 and R 15 Each is independently selected from H, unsubstituted C1-C6 straight-chain or branched alkyl, C1-C6 straight-chain or branched alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkenyl, C2-C6 straight-chain or branched alkenyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl, unsubstituted C2-C6 straight-chain or branched alkynyl, and C2-C6 straight-chain or branched alkynyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl; X is either O or NH; L is selected from the unsubstituted C1-C bond. 60 Straight-chain or branched alkylene groups, C1-C6 straight-chain or branched alkyl acyl groups or carboxyl groups substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkyl groups or carboxyl groups. 60 Straight-chain or branched alkylene, unsubstituted C2-C 60 Straight-chain or branched subalkenyl groups, C2-C substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl, or carboxyl groups. 60 Straight-chain or branched alkenyl groups, -(CR 17 R 18 -CR 19 R 20 -O) n5 - Unsubstituted arylene, arylene substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted arylene alkyl, arylene alkyl substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups, unsubstituted heterocyclic group containing 1 to 3 heteroatoms selected from N, S or O, heterocyclic group containing 1 to 3 heteroatoms selected from N, S or O substituted with hydroxyl, amino, C1-C6 straight-chain or branched alkanoyl or carboxyl groups; wherein, R 17 R 18 R 19 and R 20 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group; n5 is selected from integers from 0 to 50.

2. The compound according to claim 1, or a pharmaceutically acceptable salt or hydrate thereof, wherein, Y – Selected from chloride ions, bromide ions, iodide ions, acetate ions, trifluoroacetate ions, phosphate ions, diphosphate ions, nitrate ions, sulfate ions, benzenesulfonate ions, benzoate ions, salicylate ions, hydroxynaphthyl ions, fumarate ions, maleate ions, lactate ions, malic acid, succinate ions, tartrate ions, citrate ions, glutamate ions, gluconeate ions, and stearate ions.

3. The compound according to claim 1 or 2, or a pharmaceutically acceptable salt or hydrate thereof, wherein, R1 is -NR5(C=NH)NH2, wherein R5 is H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, preferably H; Preferably, R2 is an unsubstituted C1-C3 straight-chain or branched alkyl group or a halogen-substituted C1-C3 straight-chain or branched alkyl group, preferably CH3 or CF3; Preferably, R3 and R4 are each independently H, or unsubstituted C1-C6 straight-chain or branched alkyl groups; more preferably, R3 and R4 are H. Preferably, R6 and R 16 Each is independently selected from H, halogens and hydroxyl groups, preferably each is independently selected from H, Br and hydroxyl groups; Preferably, R7 and R 11 Each is independently a bonded or unsubstituted C1-C6 straight-chain or branched alkylene group, preferably each is independently a bonded or unsubstituted C1-C3 alkylene group; Preferably, R8, R9, R 10 and R 12 Each is an unsubstituted C1-C6 straight-chain or branched alkyl group, wherein n1, n3 and n4 are each independently selected from integers from 0 to 5, preferably 0, and n2 is selected from integers from 0 to 4, preferably 0; Preferably, R 13 R 14 and R 15 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, preferably an unsubstituted C1-C3 alkyl group; Preferably, L is selected from unsubstituted C1-C. 60 Straight-chain or branched alkylene, -(CR 17 R 18 -CR 19 R 20 -O) n5 - An unsubstituted subheterocyclic group comprising 1 to 3 heteroatoms selected from N, S, or O, wherein R 17 R 18 R 19 and R 20 Each is independently H, or an unsubstituted C1-C6 straight-chain or branched alkyl group, and n5 is selected from integers from 0 to 20; more preferably, L is selected from -(CH2). n6 -,-(CH2-CH2-O) n5 -and , where n5 and n6 are each independently selected from integers from 1 to 10.

4. The compound according to any one of claims 1 to 3, or a pharmaceutically acceptable salt or hydrate thereof, wherein, The compound has the structure shown in Formula II: 。 5. The compound according to any one of claims 1 to 4, or a pharmaceutically acceptable salt or hydrate thereof, wherein, A is selected from , , , , , , , , , , , , , and ; Preferably, the compound is selected from the following: 。 6. A method for preparing the compound according to claim 4 or 5, or a pharmaceutically acceptable salt or hydrate thereof, comprising the following steps: The compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate, is reacted with compound AH, or its pharmaceutically acceptable salt or hydrate, to obtain the compound shown in Formula II, or its pharmaceutically acceptable salt or hydrate. Wherein, the compound AH is selected from , , , , and ; R' is methyl or tert-butyl.

7. The method according to claim 6, wherein, The method includes the following steps: (1) The compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate, is coupled with compound AH, or its pharmaceutically acceptable salt or hydrate, to obtain intermediate 4, or its pharmaceutically acceptable salt or hydrate; (2) Remove the ketal, tert-butyloxycarbonyl and R' protecting group from the intermediate 4 or its pharmaceutically acceptable salt or hydrate; Preferably, the compound AH is selected from... , , , , , , , , , , , , , and .

8. The method according to claim 6 or 7, wherein, The compound represented by Formula 3, or its pharmaceutically acceptable salt or hydrate, is prepared by a method comprising the following steps: (a) The azide group of the compound represented by formula D4, or its pharmaceutically acceptable salt or hydrate, is reduced to an amino group, and the resulting compound is then subjected to a nucleophilic substitution reaction with N,N'-di-tert-butoxycarbonyl-1H-pyrazole-1-carboxamide under basic conditions to give intermediate 1, or its pharmaceutically acceptable salt or hydrate. (b) Deacetyl protecting group is removed from the acetoxy group in intermediate 1 or its pharmaceutically acceptable salt or hydrate, and the resulting compound is then ketalized with 2,2-dimethoxypropane in the presence of a catalyst and a solvent to give intermediate 2 or its pharmaceutically acceptable salt or hydrate. (c) When R' is methyl: intermediate 2, or its pharmaceutically acceptable salt or hydrate, is subjected to a nucleophilic substitution reaction with p-nitrophenyl chloroformate in the presence of a catalyst, solvent and basic auxiliaries to give the compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate; when R' is tert-butyl: intermediate 2, or its pharmaceutically acceptable salt or hydrate, is hydrolyzed under basic conditions, and the hydrolysis product is then reacted with 2-tert-butyl-1,3-diisopropylurea, and the resulting product is then subjected to a nucleophilic substitution reaction with p-nitrophenyl chloroformate in the presence of a catalyst, solvent and basic auxiliaries to give the compound shown in Formula 3, or its pharmaceutically acceptable salt or hydrate; Preferably, in step (b), the catalyst is p-toluenesulfonic acid and / or p-toluenesulfonic acid pyridinium salt, more preferably p-toluenesulfonic acid pyridinium salt; Preferably, in step (b), the solvent is dichloromethane and / or acetone, more preferably dichloromethane; Preferably, in step (c), when R' is methyl or tert-butyl, the catalyst is 4-dimethylaminopyridine; Preferably, in step (c), when R' is methyl or tert-butyl, the solvent is dichloromethane and / or pyridine, preferably dichloromethane; Preferably, in step (c), when R' is methyl or tert-butyl, the alkaline auxiliary is diisopropylethylamine.

9. A pharmaceutical composition for the prevention and / or treatment of influenza or related diseases, comprising a compound according to any one of claims 1 to 5, or a pharmaceutically acceptable salt or hydrate thereof, or a compound prepared by the method according to any one of claims 6 to 8, or a pharmaceutically acceptable salt or hydrate thereof; Preferably, the pharmaceutical composition further comprises one or more pharmaceutically acceptable excipients; Preferably, the influenza is influenza A.

10. The use of the compound of any one of claims 1 to 5, or a pharmaceutically acceptable salt or hydrate thereof, the compound of any one of claims 6 to 8, or a pharmaceutically acceptable salt or hydrate thereof, or the use of the pharmaceutical composition of claim 9 in the preparation of a medicament for the prevention and / or treatment of influenza or related diseases; Preferably, the influenza is influenza A.

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