Diester prodrug of antiviral N4-hydroxycytidine phosphate as well as preparation method and medical application of diester prodrug

Abstract

The invention discloses a diester prodrug of N hydroxyl cytidine phosphate as shown in a formula I and pharmaceutically acceptable salts thereof, a phosphate group retains a hydroxyl group, a hydrolyzable ester bond structure is contained on a side chain, and meanwhile, the N4 hydroxyl group of NHC is designed as an esterified prodrug. The diester prodrug of N-hydroxycytidine phosphate overcomes the speed limiting step of phosphorylation of NHC in cells, N4-hydroxyl easy to metabolize is protected while the design of a phosphate side chain is optimized, and the diester prodrug can be used for treating RNA virus infection by regulating the physicochemical property of diester and regulating the druggability of the prodrug. Formula I

Description

Technical Field

[0001] This invention belongs to the field of medicinal chemistry, and specifically relates to a diester prodrug of N4-hydroxycytidine phosphate, its preparation method, and its uses. Background Technology

[0002] Respiratory RNA viruses have caused numerous global public health emergencies in recent years. SARS, MERS, Ebola, Zika, and COVID-19 have all caused or are causing regional or even global pandemics. These diseases pose a serious threat to human life and health, and have caused enormous economic losses to human society.

[0003] Phosphorylation of the 5-hydroxyl group in nucleoside compounds is the rate-limiting step for these drugs to exert their antiviral effects. The 5-hydroxyphosphate of nucleoside antiviral drugs not only affects their antiviral activity but also their bioavailability. Therefore, designing phosphate prodrugs for nucleoside antiviral drugs is a key scientific issue in this field. Sofosbuvir and tenofovir alafenamide are excellent phosphate prodrugs that have achieved great success in clinical practice.

[0004] N4-Hydroxycytidine (NHC) possesses broad-spectrum antiviral activity. Merck developed its prodrug monopravir (CAS No: 2492423-29-5, code name EIDD-2801) for marketing as an anti-SARS-CoV-2 drug; however, due to metabolic reasons, its oral dose is as high as 1600 mg / day for adults. In vivo metabolic studies show that monopravir rapidly releases the antiviral active ingredient NHC in vivo. However, NHC needs to be phosphorylated in vivo to the triphosphate form NHC-TP to exert its antiviral effect. The key step in NHC phosphorylation is the first step, the monophosphorylation of the 5-hydroxyl group of the NHC sugar ring. Therefore, to overcome this rate-limiting step, phosphate ester prodrugs of NHC have been designed. For example, WO 2017 / 156380 A1 (CN 107427529 A) reported a class of NHC phosphate ester prodrugs, whose structures are mainly based on the structures of phosphate prodrug esters such as sofosbuvir and tenofovir alafenamide, including... , , , , Chinese patent CN 116554249 B discloses a class of phosphate prodrugs for NHC. Its main characteristic is that the Z group of the aliphatic side chain of the phosphate ester has a disulfide bond structure; Chinese patent CN118591377A discloses a class of long-acting phosphate ester prodrugs. Its main characteristic is that the side chain contains a glycerol structure, for example , , , wait.

[0005] However, the hydrolytic release of phosphate ester prodrugs remains a key issue that needs further exploration in the field. Depending on the combination of nucleoside and carrier fragments, different possibilities arise for the hydrolysis of phosphate esters in vivo. Phosphate ester prodrugs can hydrolyze the ester bond between the phosphate group and the carrier to yield N4-hydroxycytidine phosphate (NHC-P), or they may hydrolyze and break the ester bond between the 5-hydroxy group of NHC and the phosphate group, returning to NHC. Furthermore, the N4-hydroxy group of NHC is also a site prone to metabolic inactivation, requiring prodrug design for protection. However, there are currently no research reports on diester prodrugs of NHC-N4-hydroxy and NHC-glycocyclic 5-hydroxyphosphate. This may be because the more steps involved in the prodrug release of the active ingredient, the lower the release efficiency. For example, the drug release mechanism of the diester prodrug of NHC-N4-hydroxy and NHC-glycocyclic 5-hydroxyphosphate shown in Formula A includes the breaking of ester bonds at positions 1, 1', 2, and 3 (shown by dashed lines), leading to uncertainty in prodrug release efficiency. Therefore, the design of diester prodrugs remains a current technological challenge.

[0006] Formula A Summary of the Invention The purpose of this invention is to provide a class of diester prodrugs of N-hydroxycytidine phosphate and their pharmaceutically acceptable salts, characterized in that the phosphate group retains a hydroxyl group, the side chain contains a hydrolyzable ester bond structure, and the N4 hydroxyl group of NHC is designed as an esterification prodrug.

[0007] On the one hand, the present invention provides a diester prodrug of N-hydroxycytidine phosphate as shown in Formula I and a pharmaceutically acceptable salt thereof. Formula I in: R1 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C13 straight-chain or branched alkyl ester, C2-C13 straight-chain or branched alkenyl ester, C2-C13 straight-chain or branched alkynyl ester, C6-C18 aryl, C1-C6 straight-chain or branched alkyl, C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide. Preferably, R1 is selected from C1-C15 straight-chain or branched alkyl, C2-C15 straight-chain or branched alkenyl, C2-C15 straight-chain or branched alkynyl, C1-C13 straight-chain or branched alkyl ester, C2-C13 straight-chain or branched alkenyl ester, C2-C13 straight-chain or branched alkynyl ester, C6-C10 aryl, C1-C6 straight-chain or branched alkyl, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C15 straight-chain or branched alkylamide, C2-C15 straight-chain or branched alkenylamide, and C2-C15 straight-chain or branched alkynylamide.

[0008] Preferably, R1 is selected from C1-C11 straight-chain or branched alkyl, C2-C11 straight-chain or branched alkenyl, C2-C11 straight-chain or branched alkynyl, C6-C10 aryl, C1-C3 straight-chain or branched alkyl, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O or N, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O or N, C1-C11 straight-chain or branched alkylamide, C2-C11 straight-chain or branched alkenylamide, and C2-C11 straight-chain or branched alkynylamide. Preferably, R1 is selected from C1-C11 straight-chain or branched alkyl groups.

[0009] R2 is selected from C1-C25 straight-chain or branched alkyl, C2-C25 straight-chain or branched alkenyl, C2-C25 straight-chain or branched alkynyl, C3-C25 straight-chain or branched alkyl containing 1-4 oxygen atoms (-O-), C3-C25 straight-chain or branched alkyl ester, C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1 -C25 straight-chain or branched alkyl amide group, C2-C25 straight-chain or branched alkenyl amide group, C2-C25 straight-chain or branched alkynyl amide group, wherein in C3-C25 straight-chain or branched alkyl groups containing 1-4 oxygen groups (-O-), the oxygen group may be located at any position in the alkyl chain as long as the valence allows; in C3-C25 straight-chain or branched alkyl ester group, the ester group (-COO-) may be located at any position in the alkyl chain as long as the valence allows; Preferably, R2 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-4 oxygen atoms (-O-), C3-C20 straight-chain or branched alkyl ester, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, and 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S. C1-C20 straight-chain or branched alkyl amide groups, C2-C20 straight-chain or branched alkenyl amide groups, C2-C20 straight-chain or branched alkynyl amide groups, wherein in C3-C20 straight-chain or branched alkyl groups containing 1-4 oxygen groups (-O-), the oxygen group may be located at any position on the alkyl chain as long as the valence allows; in C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) may be located at any position on the alkyl chain as long as the valence allows.

[0010] Preferably, R2 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-4 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl containing 1-4 oxygen groups (-O-), the oxygen group can be located at any position on the alkyl chain as long as the valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position on the alkyl chain as long as the valence allows.

[0011] Preferably, R2 is selected from C1-C10 straight-chain or branched alkyl, C2-C10 straight-chain or branched alkenyl, C2-C10 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), the oxygen group can be located at any position on the alkyl chain as long as the chemical valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position on the alkyl chain as long as the chemical valence allows.

[0012] Preferably, R2 is selected from C1-C10 straight-chain or branched alkyl groups, C3-C20 straight-chain or branched alkyl groups containing 1-3 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl groups containing 1-3 oxygen groups (-O-), the oxygen group can be located at any position on the alkyl chain, provided that the chemical valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position on the alkyl chain, provided that the chemical valence allows.

[0013] Preferably, the diester prodrug of N-hydroxycytidine phosphate according to Formula I of the present invention and its pharmaceutically acceptable salt can be represented by Formula I-1 or Formula I-2:

[0014] The definition of substituent R1 is the same as that in Equation I above; R21 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C1-C20 straight-chain or branched alkyl substituted with oxo groups (O=), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows.

[0015] Preferably, R21 is selected from C1-C18 straight-chain or branched alkyl, C2-C18 straight-chain or branched alkenyl, C2-C18 straight-chain or branched alkynyl, C1-C18 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C1-C10 straight-chain or branched alkyl substituted with oxo groups (O=), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C18 straight-chain or branched alkylamide, C2-C18 straight-chain or branched alkenylamide, and C2-C18 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows.

[0016] Preferably, R21 is selected from C1-C18 straight-chain or branched alkyl groups, C1-C18 straight-chain or branched alkyl groups containing 1 or 2 oxygen groups (-O-), and C1-C10 straight-chain or branched alkyl groups substituted with oxo groups (O=), wherein the oxygen group is located at any position on the alkyl chain, provided that the valence allows.

[0017] R22 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows.

[0018] Preferably, R22 is selected from C1-C18 straight-chain or branched alkyl, C2-C18 straight-chain or branched alkenyl, C2-C18 straight-chain or branched alkynyl, C1-C18 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C18 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows.

[0019] Preferably, R22 is selected from C1-C18 straight-chain or branched alkyl groups, C1-C18 straight-chain or branched alkyl groups containing 1 or 2 oxygen groups (-O-), wherein the oxygen group can be located at any position on the alkyl chain, provided that the chemical valence allows.

[0020] n is an integer from 1 to 6; Preferably, n is an integer from 1 to 4.

[0021] Preferably, n is an integer of 1, 2, or 3.

[0022] More preferably, the compounds represented by Formula I, Formula I-1, or Formula I-2 are selected from specific compounds A1 to A33 with the following structures:

[0023] In another aspect, the present invention provides a method for preparing a diester prodrug of N-hydroxycytidine phosphate represented by Formula I and a pharmaceutically acceptable salt thereof:

[0024] As shown in the reaction formula above, the method includes the following steps: i-1) Compound 1a is protected with silane and then undergoes a one-pot reaction involving chlorination and amine substitution to generate compound 2a. i-2) Compound 2a undergoes an acetone cross condensation reaction to generate compound 3a. i-3) Compound 3a undergoes a silane protection reaction to regenerate compound 4a. i-4) Compound 4a undergoes an amine substitution reaction to generate compound 5a. i-5) Compound 5a is restructured through condensation and other reactions to generate compound 6a with the corresponding R1 group. i-6) Compound 6a undergoes a deprotection reaction of the silyl ether protecting group to regenerate compound 7a. i-7) Compound 7a undergoes a condensation reaction to form a phosphite compound 8a. i-8) Compound 8a undergoes substitution and oxidation reactions to generate compound 9a containing the R2 group. i-9) Compound 9a undergoes a hydrolysis reaction to remove the acetone cross protection, yielding compound 10a. i-10) Compound 10a undergoes a reverse Michael addition reaction to remove the cyanoethyl group, yielding compound of general formula I.

[0025] In the above reaction formula, the substituents R1 and R2 are defined in the same way as in Formula I above.

[0026] Preferably, in step i-1), trimethylchlorosilane is used as the silanization protecting agent, phosphorus oxychloride is used as the chlorination agent, and 1,2,4-triazole is used as the transition nucleophile to carry out the amine substitution reaction, and the reaction is carried out at 0~25°C.

[0027] Preferably, in step i-2), sulfuric acid is used as a catalyst, and 2,2-dimethoxypropane and compound 2a undergo a condensation reaction at 25-40°C.

[0028] Preferably, in step i-3), tert-butyldimethylchlorosilane is used as a silanization protecting agent, and the reaction is carried out at room temperature.

[0029] Preferably, in step i-4), hydroxylamine hydrochloride is used as the final nucleophilic substitution agent to replace triazole, and the reaction is carried out at room temperature.

[0030] Preferably, in step i-5), a condensation reaction is carried out using the corresponding acid or acyl chloride at room temperature.

[0031] Preferably, in step i-6), tetrabutylammonium fluoride is used to remove the silyl ether protecting group, and the reaction is carried out at room temperature.

[0032] Preferably, in step i-7), N,N-diisopropylethylamine is used as an acid-binding agent for the condensation reaction, and the reaction is carried out at room temperature.

[0033] Preferably, in steps i-8), a substitution reaction is carried out using the corresponding alcohol, and an oxidation reaction is carried out using tert-butylhydrogen oxidant to obtain the corresponding phosphate ester compound 9a, and the reaction is carried out at room temperature.

[0034] Preferably, in step i-9), formic acid is used as a catalyst, and the reaction is carried out at room temperature.

[0035] Preferably, in step i-10), triethylamine is used for a reverse Michael addition reaction, which is carried out at room temperature.

[0036] On the other hand, the present invention provides a pharmaceutical composition comprising a therapeutically effective amount of the above-mentioned diester prodrug of N-hydroxycytidine phosphate and its pharmaceutically acceptable salt, and optionally pharmaceutically acceptable excipients.

[0037] Wherein, the pharmaceutically acceptable salt is a base addition salt of a compound of general formula (I), wherein the base used for salt formation includes inorganic bases and organic bases; wherein, the inorganic salts include: sodium salts, potassium salts, lithium salts, and barium salts; and the organic salts include: amine salts, triethylamine salts, and pyridine salts.

[0038] In another aspect, the present invention provides the use of the above-mentioned diester prodrug of N-hydroxycytidine phosphate and its pharmaceutically acceptable salt or the above-mentioned pharmaceutical composition in the preparation of a drug for treating viral infections.

[0039] The viruses mentioned are RNA viruses, including coronaviruses, influenza viruses, rhabdoviruses, paramyxoviruses, respiratory syncytial viruses, flaviviridae viruses, filoviridae viruses, human metapneumoviruses, porcine epidemic diarrhea viruses, Bunyaviridae viruses, and arenaviruses.

[0040] In a specific implementation, the virus is an influenza virus, a coronavirus respiratory syncytial virus, or a human metapneumovirus.

[0041] Beneficial effects The N-hydroxycytidine phosphate diester prodrug of the present invention overcomes the rate-limiting step of NHC phosphorylation in cells. While optimizing the design of the phosphate ester side chain, it protects the easily metabolized N4-hydroxyl group. By regulating the physicochemical properties of the diester, the drug-likeness of the prodrug is controlled, and it has very good biological activity in the treatment of influenza virus and vesicular stomatitis virus infection. Detailed Implementation

[0042] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this description and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical method of the present invention, based on the principle that the inventors are allowed to appropriately define the terminology for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0043] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0044] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0045] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0046] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0047] In this document, when Markush groups or alternative terms are used to describe features or examples of the invention, those skilled in the art should understand that subgroups of all elements within a Markush group or option list, or any individual element, can also be used to describe the invention. For example, if X is described as "selected from the group consisting of X1, X2, and X3," it also indicates that the claim that X is X1 and the claim that X is X1 and / or X2 have been fully described. Furthermore, when Markush groups or alternative terms are used to describe features or examples of the invention, those skilled in the art should understand that any combination of subgroups of all elements within a Markush group or option list, or any combination of individual elements, can also be used to describe the invention. Accordingly, for example, if X is described as "selected from the group consisting of X1, X2, and X3," and Y is described as "selected from the group consisting of Y1, Y2, and Y3," it indicates that the claim that X is X1 or X2 or X3 and Y is Y1 or Y2 or Y3 has been fully described.

[0048] definition As used herein, the term "alkyl" alone or as part of another group refers to a straight-chain or branched aliphatic saturated hydrocarbon. In some embodiments, the alkyl group may contain 1 to 20 carbon atoms (i.e., C64-C ... 1-20 Alkyl group or a specified number of carbon atoms (i.e., C1 alkyl (e.g., methyl), C2 alkyl (e.g., ethyl), C3 alkyl (e.g., propyl or isopropyl), etc.). In one embodiment, the alkyl group is a straight-chain C1 alkyl group. 1-20 Alkyl group. In another embodiment, the alkyl group is a straight-chain C14 group. 1-18 Alkyl groups. For example, C14 used in this article. 1-4 Alkyl groups are selected from methyl, ethyl, propyl (n-propyl), isopropyl, butyl (n-butyl), sec-butyl, tert-butyl, and isobutyl groups. Optional substitution of C0 1-4 Alkyl refers to the C1646-C ... 1-4 Alkyl groups, optionally substituted with one or more permitted substituents as described herein. As used herein, the term "alkylene," when used alone or as part of another group, refers to a divalent group derived from an alkyl group. For example, non-limiting straight-chain alkylene groups include -CH2-CH2-CH2-CH2-, -CH2-CH2-CH2-, -CH2-CH2-, etc.

[0049] As used herein, the term "alkenyl," when used alone or as part of another group, refers to an alkyl group as defined above containing one, two, or three carbon-carbon double bonds. In one embodiment, the alkenyl group is C0. 2-18 Alkenyl group. In another embodiment, the alkenyl group is C. 2-4 Alkenyl. Non-limiting exemplary alkenyl groups include vinyl, propenyl, isopropenyl, butenyl, sec-butenyl, pentenyl, and hexenyl.

[0050] As used herein, the term "alkynyl," when used alone or as part of another group, refers to an alkyl group as defined above containing one to three carbon-carbon triple bonds. In one embodiment, the alkynyl group has one carbon-carbon triple bond. In one embodiment, the alkynyl group is a C2-20 alkynyl group. In another embodiment, the alkynyl group is a C2-18 alkynyl group. Non-limiting exemplary alkynyl groups include ethynyl, propynyl, butynyl, 2-butynyl, pentyynyl, and hexynyl.

[0051] As used herein, the term "alkanoyl", when used alone or as part of another group, refers to formula R ’ The group of CO, wherein R' is an alkyl group as defined above.

[0052] As used herein, the term "alkanoyloxy," when used alone or as part of another group, refers to formula R ’ COO groups, where R ’ It is an alkyl group as defined above.

[0053] As used herein, the term "alkylaminoalkylacyl" when used alone or as part of another group refers to the formula NHCOR. ’ The group, wherein R ’ It is an alkyl group as defined above.

[0054] As used herein, the term "alkoxyalkylyl" when used alone or as part of another group refers to the formula OR ’ COOR ’ The group, wherein R ’ It is an alkyl group as defined above.

[0055] The term "halogenated," used alone or as part of another group, refers to a compound in which one or more hydrogen atoms are replaced by atoms selected from fluorine, chlorine, bromine, and / or iodine. For example, a haloalkyl group is an alkyl group substituted with one, two, or three fluorine atoms.

[0056] "Heterocyclic group" or "heterocycle," used alone or as part of another group, refers to a group having a 5- to 10-membered non-aromatic ring system having a ring carbon atom and 1 to 4 ring heteroatoms (each heteroatom independently selected from nitrogen, oxygen, and sulfur) ("5- to 10-membered heterocyclic group"). Where valence permits, in a heterocyclic group containing one or more nitrogen or oxygen atoms, the linking point can be a carbon, nitrogen, or oxygen atom. Heterocyclic groups can be monocyclic ("monocyclic heterocyclic group") or fused, bridged, or spirocyclic systems, such as bicyclic systems ("bicyclic heterocyclic group"), and can be saturated or partially unsaturated. A bicyclic heterocyclic system may contain one or more heteroatoms in one or both rings. "Heterocyclic group" also includes a ring system in which a heterocycle as defined above is fused with one or more carbocyclic groups, wherein the connection point is on the carbocyclic group or the heterocycle, or a ring system in which a heterocycle as defined above is fused with one or more aryl or heteroaryl groups, wherein the connection point is on the heterocycle, and in this case, the number of ring members continues to represent the number of ring members in the heterocyclic system.

[0057] “Aryl”, used alone or as part of another group, refers to a monocyclic or polycyclic (e.g., bicyclic or tricyclic) 4n+2 aromatic ring system (e.g., having 6, 10, 14, or 18 π electrons shared in the ring array) having 6-18 carbon atoms and 0 heteroatoms in an aromatic ring system (“C6-18 aryl”). In some embodiments, the aryl has 6 ring carbon atoms (“C6 aryl”; e.g., phenyl). In some embodiments, the aryl has 10 ring carbon atoms (“C10 aryl”; e.g., naphthyl, such as 1-naphthyl and 2-naphthyl). In some embodiments, the aryl has 14 ring carbon atoms (“C14 aryl”; e.g., anthracene). “Aryl” also includes ring systems in which the aryl ring as defined above is fused with one or more carbocyclic or heterocyclic groups, wherein the radical or connecting point is on the aryl ring, and in this case, the number of carbon atoms continues to represent the number of carbon atoms in the aromatic ring system.

[0058] "Heteroaryl," used alone or as part of another group, refers to a group ("5-10 membered heteroaryl") having a cyclic carbon atom provided in the aromatic ring system and 1-4 cyclic heteroatoms (each heteroatom independently selected from nitrogen, oxygen, and sulfur) of a 5-10 membered monocyclic or bicyclic 4n+2 aromatic ring system (e.g., having 6 or 10 π electrons shared in the ring array). Where valence permits, in heteroaryl containing one or more nitrogen atoms, the linking point can be a carbon or nitrogen atom. A heteroaryl bicyclic system may contain one or more heteroatoms in one or both rings. "Heteroaryl" includes ring systems in which the heteroaryl ring as defined above is fused with one or more carbocyclic or heterocyclic groups, wherein the linking point is on the heteroaryl ring, and in this case, the number of ring members continues to indicate the number of ring members in the heteroaryl ring system. "Heteroaryl" also includes ring systems in which a heteroaryl ring as defined above is fused with one or more aryl groups, wherein the connection point is on the aryl or heteroaryl ring, and in this case, the number of ring members represents the number of ring members in the fused (aryl / heteroaryl) ring system. A bicyclic heteroaryl group (e.g., indolyl, quinolinyl, carbazolyl, etc.) in which one ring does not contain a heteroatom can have the connection point on either ring, i.e., a ring with a heteroatom (e.g., 2-indolyl) or a ring without a heteroatom (e.g., 5-indolyl).

[0059] The term "pharmaceutically acceptable salt" refers to salts that, within reasonable medical judgment, are suitable for contact with the tissues of humans and lower animals without excessive toxicity, irritation, allergic reactions, etc., and in proportion to a reasonable benefit / risk ratio. Pharmaceutically acceptable salts are well known in the art.

[0060] When listing a range of values, the intention is to include every value within that range and its subranges. For example, "C 1-6 "Aims to cover C1, C2, C3, C4, C5, C6, C 1-6 C 1-5 C 1-4 C 1-3 C 1-2 C 2-6 C 2-5 C 2-4 C 2-3 C 3-6 C 3-5 C 3-4 C 4-6 C 4-5 and C 5-6 .

[0061] Some embodiments relate to pharmaceutical compositions comprising one or more compounds of the present disclosure. The pharmaceutical composition may optionally comprise a pharmaceutically acceptable excipient. In some embodiments, the pharmaceutical composition comprises a compound represented by Formula I of the present disclosure or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient. Pharmaceutically acceptable excipients are well known in the art. Suitable excipients include, but are not limited to, encapsulating materials or additives such as absorption enhancers, antioxidants, binders, buffers, carriers, coatings, colorants, diluents, disintegrants, emulsifiers, swelling agents, fillers, flavoring agents, humectants, lubricants, fragrances, preservatives, propellants, release agents, bactericides, sweeteners, solubilizers, wetting agents, and mixtures thereof.

[0062] The present invention will be further described below. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0063] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0064] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0065] Example 1: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}[2-(octanoyloxy)ethoxy]phosphonic acid A1 (mch-2328)

[0066]

[0067]

[0068] Compound 1a (6.0 g, 24.6 mmol) was added to acetonitrile (39 mL), followed by N-methylpyrrolidine (38.5 mL, 369 mmol) and trimethylchlorosilane (15.6 mL, 123 mmol). After the additions were complete, the reaction was carried out at 30 °C for 60 min under a nitrogen atmosphere. Phosphorus oxychloride (4.5 mL, 49.2 mmol) was added dropwise under an ice bath, and the mixture was stirred for 20 min. Then, 1,2,4-triazole (16.9 g, 246 mmol) was added, and the reaction was carried out under an ice bath for 60 min, followed by a reaction at 30 °C for 2 h. TLC showed that the reaction was complete. The reaction solution was diluted with dichloromethane (37.5 mL), and the reaction was quenched with saturated sodium chloride aqueous solution (150 mL). The organic phase was separated, and the aqueous phase was extracted four times with dichloromethane. The combined organic phases were dried over anhydrous sodium sulfate. After filtration, the solvent was evaporated, methanol (30 mL) was added and stirred to dissolve, and acetic acid (3 mL) was added. The mixture was stirred at 30 °C for 10 h, and a large amount of solid precipitated. After filtration and drying, compound 2a was obtained as a pale yellow solid (5.8 g, 79.9%).

[0069] Compound 2a (5.5 g, 18.6 mmol) was added to acetonitrile (55 mL), followed by 2,2-dimethoxypropane (4.6 mL, 37.2 mmol) and concentrated sulfuric acid (2 mL). The reaction was then carried out at 30 °C for 10 h under a nitrogen atmosphere. TLC showed that the reaction was complete. The mixture was filtered to give compound 3a as a white solid (5.0 g, 80.0%).

[0070] Compound 3a (5.0 g, 16.9 mmol) was added to N,N-dimethylformamide (33 mL), followed by tert-butyldimethylchlorosilane (3.1 mg, 20.3 mmol) and imidazole (2.7 g, 38.9 mmol). The reaction was then carried out at 30 °C for 8 hours, and TLC showed that the reaction was complete. The reaction solution was added to 150 mL of deionized water, and a large amount of solid precipitated. The solid was filtered, dried, and compound 4a was obtained (6.9 g, 99.4% purity, white solid).

[0071] Compound 4a (6.9 g, 16.8 mmol) was added to ethyl acetate (100 mL), followed by hydroxylamine hydrochloride (1.8 g, 25.4 mmol) and triethylamine (4.6 mL, 33.9 mmol). The mixture was stirred at 30 °C for 10 h under nitrogen protection. TLC showed that the reaction was complete. The reaction solution was diluted with ethyl acetate (50 mL), washed with deionized water (150 mL), and the organic phase was separated and dried over anhydrous sodium sulfate. The mixture was filtered, and the solvent was evaporated to give compound 5a as a yellow solid (6.6 g, 95.1%).

[0072] Compound 5a (6.5 g, 15.7 mmol) was added to dichloromethane (50 mL), followed by the addition of triethylamine (3.3 mL). The mixture was stirred and dissolved under a nitrogen atmosphere, then cooled in an ice bath. Acetyl chloride (1.3 g, 16.5 mmol) dissolved in 10 mL of dichloromethane was then added dropwise. After the addition was complete, the mixture was stirred at 30 °C for 2 h. TLC showed that the reaction was complete. The reaction mixture was washed with deionized water (100 mL), separated, and the organic phase was dried over anhydrous sodium sulfate. The mixture was filtered, and the solvent was evaporated to obtain compound 6a-1 as a yellow solid (6.5 g, 90.9%).

[0073] Compound 6a-1 (6.5 g, 14.3 mmol) was added to tetrahydrofuran (50 mL) and stirred to dissolve. Then, a 1 M tetrabutylammonium fluoride solution in tetrahydrofuran (17 mL) was added dropwise, and the mixture was stirred at 30 °C for 4 h after the addition was complete. TLC showed that the reaction was complete. The reaction solution was washed with deionized water (100 mL), separated, and the organic phase was dried over anhydrous sodium sulfate. After filtration and solvent removal by rotary evaporation, DCM:MeOH = 25:1 silica gel column chromatography was performed to give compound 7a-1 as a white solid (3.17 g, 64.9%).

[0074] Compound 7a-1 (682 mg, 2 mmol) was added to DCM (15 mL), followed by N,N-diisopropylethylamine (516 mg, 4 mmol). The mixture was stirred until dissolved, and then 2-cyanoethyl N,N-diisopropylphosphonamide (709 g, 3 mmol) was added. The reaction was carried out at 30 °C for 1.5 h under a nitrogen atmosphere. TLC showed that the reaction was complete. The reaction solution was washed with deionized water (100 mL), separated, and the organic phase was dried over anhydrous sodium sulfate. The mixture was filtered, and the solvent was evaporated to obtain crude adduct 8a-1, which was a colorless, transparent, viscous liquid.

[0075] The crude compound 8a-1 was added to anhydrous acetonitrile (50 mL), followed by 2-hydroxyethyl octanoate (752 mg, 4 mmol). The mixture was stirred until dissolved, and a 1H-tetrazole acetonitrile solution (0.45 M, 13.3 mL, 6 mmol) was added dropwise under an ice bath. The reaction was carried out at 30 °C for 2 h under a nitrogen atmosphere. TLC showed complete reaction. A (5.0-6.0 M in Decane) tert-butyl hydroperoxide solution (1.45 mL, 8 mmol) was added, and the reaction was carried out at 30 °C for 2 h under a nitrogen atmosphere. TLC showed complete reaction. The reaction solution was diluted with 30 mL of ethyl acetate, quenched with 100 mL of saturated sodium thiosulfate aqueous solution, separated, and the organic phase was dried over anhydrous sodium sulfate. The mixture was filtered, the solvent was evaporated, and DCM:MeOH = 40:1 silica gel column chromatography was performed to obtain compound 9a-1 as a colorless, transparent viscous liquid (698.0 mg, 54.3%).

[0076] Compound 9a-1 (690 mg, 1.07 mmol) was added to formic acid (4 mL) and reacted at 30 °C for 12 h. TLC showed that the reaction was complete. After the solvent was evaporated, compound 10a-1 was obtained by silica gel column chromatography in DCM:MeOH = 30:1 as a colorless and transparent viscous liquid (253.9 mg, 36.7%).

[0077] Compound 10a-1 (220 mg, 0.364 mmol) was added to pyridine (2 mL) and triethylamine (2 mL) was added. The reaction was carried out at 30 °C for 16 h. TLC showed that the reaction was complete. The solvent was evaporated and silica gel column chromatography with DCM:MeOH = 8:1 was used to obtain compound A1 as a white solid (91.9 mg, 45.8%). 1 H NMR (400 MHz, DMSO-d6) δ 11.18 – 10.81 (m, 1H), 7.61 –7.29 (m, 1H), 5.87 (dd, J = 78.7, 7.2 Hz, 1H), 5.70 (dd, J = 38.2, 7.0 Hz, 1H), 5.45 (d, J = 5.6 Hz, 1H), 5.38 (s, 1H), 4.10 (t, J = 4.9 Hz, 2H), 4.03(q, J = 5.6 Hz, 1H), 3.97 (s, 1H), 3.90 (d, J = 3.5 Hz, 1H), 3.82 (d, J =12.6 Hz, 4H), 3.16 (d, J = 3.3 Hz, 1H), 2.28 (t, J = 7.4 Hz, 2H), 2.10 (d, J= 4.5 Hz, 3H), 1.49 (p, J = 7.3 Hz, 2H), 1.23 (d, J = 3.9 Hz, 8H), 0.84 (t, J= 6.8 Hz, 3H). Example 2: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}[2-(hexanoyloxy)ethoxy]phosphonic acid A2 (mch-2332)

[0078] Compound A2 was prepared as described in Example 1, A1, and was a white solid with a yield of 3.11%. 1 H NMR (400MHz, DMSO- d6) δ 10.03 (s, 1H), 9.42 (d, J = 22.6 Hz, 1H), 7.03 (d, J = 8.3 Hz, 1H), 5.74 (d, J = 6.4 Hz, 1H), 5.52 (d, J = 8.2 Hz, 1H), 5.38 (d, J = 5.6 Hz, 2H), 4.09 (t, J = 5.0 Hz, 2H), 4.00 (q, J = 5.6 Hz, 1H), 3.95 (dd, J = 5.3, 2.7 Hz, 1H), 3.85 (q, J = 3.5 Hz, 1H), 3.82 – 3.76 (m, 2H), 3.73 (dd, J = 5.7, 3.6 Hz, 2H), 2.29 (t, J = 7.5 Hz, 2H), 1.51 (p, J = 7.3 Hz, 2H), 1.36 – 1.12 (m, 6H), 0.84 (t, J = 6.8 Hz, 4H). Example 3: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy}(octoxy)phosphonic acid A3 (mch-2333)

[0079] Compound A3 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 4.52%. 1 H NMR (400MHz, DMSO- d 6) δ 10.03 (s, 1H), 9.41 (d, J = 15.6 Hz, 1H), 7.04 (d, J = 8.2 Hz, 1H), 5.73 (d, J = 6.3 Hz, 1H), 5.58 – 5.32 (m, 3H), 4.03 – 3.90 (m, 2H), 3.85(d, J = 3.4 Hz, 1H), 3.72 (t,J = 4.5 Hz, 2H), 3.60 (q, J = 6.6 Hz, 2H), 1.46 (p, J =6.6 Hz, 2H), 1.23 (s, 13H), 0.85 (t, J = 6.6 Hz, 3H). Example 4: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}[3-(3-butoxypropoxy)propoxy]phosphonic acid A4 (mch-2339)

[0080] Compound A4 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 5.33%. 1 H NMR (400MHz, DMSO- d 6) δ 10.99 (d, J = 100.7 Hz, 1H), 7.20 (d, J = 151.3 Hz, 1H), 6.10 –5.60 (m, 2H), 5.61 – 4.97 (m, 2H), 4.36 – 4.11 (m, 1H), 4.09 – 3.69 (m, 5H), 3.50 (qt, J = 8.7, 6.0, 5.3 Hz, 2H), 3.41 – 3.35 (m, 2H), 3.34 – 3.15 (m, 6H), 2.09 (d, J = 6.0 Hz, 3H), 1.50 – 1.36 (m, 2H), 1.30 (tq, J = 11.5, 3.8, 3.2 Hz,2H), 1.15 (d, J = 6.9 Hz, 2H), 1.02 (td, J = 6.2, 3.2 Hz, 2H), 0.91 – 0.79 (m,3H).MS m / z =554.2[M+H] + .

[0081] Example 5: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}[3-(hexadecyloxy)propoxy]phosphonic acid A5 (mch-2340)

[0082] Compound A5 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 4.88%. 1 H NMR (400MHz, DMSO- d 6) δ 10.99 (d, J = 102.2 Hz, 1H), 10.16 – 9.30 (m, 1H), 7.19 (dd, J =153.0, 8.2 Hz, 1H), 5.88 (dd, J = 81.9, 6.9 Hz, 1H), 5.76 – 5.61 (m, 1H), 5.61– 5.16 (m, 2H), 4.02 (dt, J = 16.3, 5.6 Hz, 2H), 3.96 – 3.63 (m, 5H), 3.37 (t, J = 6.4 Hz, 2H), 3.32 – 3.22 (m, 2H), 2.09 (d, J = 5.6 Hz, 2H), 1.73 (p, J = 6.5Hz, 2H), 1.44 (t, J = 6.9 Hz, 2H), 1.22 (d, J = 3.0 Hz, 24H), 1.16 (t, J = 7.3 Hz, 3H), 0.85 (t, J = 6.7 Hz, 3H).MS m / z =664.3[M+H] + .

[0083] Example 6: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}({3-[3-(3-butoxypropoxy)propoxy]propoxy})phosphonic acid A6 (mch-2342)

[0084] Compound A6 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 4.23%. 1 H NMR (400MHz, DMSO- d 6) δ 10.17 – 9.23 (m, 1H), 7.21 (d, J = 152.5 Hz, 1H), 6.18 – 5.60(m, 2H), 5.60 – 5.13 (m, 2H), 4.18 (s, 1H), 4.01 (d, J = 9.7 Hz, 2H), 3.91 (d, J = 16.1 Hz, 3H), 3.56 – 3.23 (m, 14H), 2.09 (d, J = 6.2 Hz, 3H), 1.44 (h, J = 6.3,5.8 Hz, 2H), 1.35 – 1.27 (m, 2H), 1.16 (d, J = 5.8 Hz, 2H), 1.02 (dd, J = 4.1, 2.1 Hz, 4H), 0.86 (t, J = 7.4 Hz, 3H). Example 7: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy}(dodecyloxy)phosphonic acid A7 (mch-2773)

[0085] Compound A7 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 3.82%. 1 H NMR (400MHz, DMSO- d 6) δ 10.98 (d, J = 101.0 Hz, 1H), 7.62 – 7.32 (m, 1H), 5.80 – 5.71(m, 1H), 5.39 (d, J = 5.4 Hz, 1H), 4.04 (q, J = 5.4 Hz, 1H), 3.98 (t, J = 4.4 Hz, 1H), 3.90 (d, J = 3.5 Hz, 1H), 3.79 (s, 2H), 3.63 (q,J = 6.7 Hz, 2H), 3.01 (q, J =7.2 Hz, 4H), 2.09 (d, J = 6.4 Hz, 3H), 1.47 (p, J = 6.9 Hz, 2H), 1.24 – 1.17 (m,18H), 0.85 (t, J = 6.7 Hz, 3H).MS m / z =550.2[M+H] + .

[0086] Example 8: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy}({2-[(4-methylpentanoyl)oxy]ethoxy})phosphonic acid A8 (mch-2775)

[0087] Compound A8 was prepared according to the preparation of A1 in Example 1, and was a white solid with a yield of 4.12%. 1 H NMR (400MHz, DMSO- d 6) δ 11.27 – 10.73 (m, 1H), 7.68 – 7.17 (m, 1H), 6.07 – 5.74 (m,1H), 5.66 – 5.20 (m, 2H), 4.11 (t, J = 5.0 Hz, 2H), 4.04 (q, J = 5.5 Hz, 1H),4.01 – 3.95 (m, 1H), 3.91 (s, 1H), 3.84 (s, 3H), 3.04 (q, J = 7.3 Hz, 3H), 2.35– 2.21 (m, 2H), 2.10 (d, J = 4.1 Hz, 3H), 1.16 (d, J = 7.3 Hz, 3H), 0.84 (d, J =6.5 Hz, 6H).MS m / z =524.1[M+H] + .

[0088] Example 9: {[(2R,3S,4R,5R)-5-{4-[(acetoxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy}[(4-methylpentyl)oxy]phosphonic acid A9 (mch-3305)

[0089] Example 10: [3-(3-butoxypropoxy)propoxy]({[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy})phosphonic acid A10 (mch-2311)

[0090] Compound A10 was prepared using compound 5a as the starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 4.11%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.02 (d, J = 118.4 Hz, 1H), 7.39 (t, J = 8.8Hz, 1H), 5.87 (dd, J = 61.1, 6.9 Hz, 1H), 5.77 – 5.65 (m, 1H), 5.41 (s, 1H), 4.21 (s, 1H), 4.09 – 3.97 (m, 2H), 3.94 (s, 3H), 3.59 – 3.42 (m, 2H), 3.42 –3.35 (m, 2H), 3.30 – 3.18 (m, 2H), 2.96 (s, 1H), 2.81 (hept, J = 6.9 Hz, 1H), 1.43 (dtd, J = 10.8, 7.4, 7.0, 3.8 Hz, 2H), 1.35 – 1.23 (m, 3H), 1.17 (t, J = 5.6Hz, 5H), 1.11 (d, J = 7.0 Hz, 5H), 1.03 (ddt, J = 10.1, 5.0, 2.3 Hz, 3H), 0.85(td, J = 7.3, 2.0 Hz, 3H).MS m / z =582.1[M+H]+ .

[0091] Example 11: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy}(dodecyloxy)phosphonic acid A11 (mch-2317)

[0092] Compound A11 was prepared using compound 8a-10 as a starting material, referring to the preparation of A1 in Example 1. It was a white solid with an overall yield of 5.47%. 1 H NMR (400 MHz, DMSO- d 6) δ 7.56 (d, J = 8.3 Hz, 1H), 7.42 (d, J = 8.2 Hz,1H), 6.00 – 5.59 (m, 2H), 5.47 (d, J = 5.7 Hz, 2H), 4.00 (dt, J = 18.5, 5.1 Hz, 2H), 3.90 (q, J = 3.4 Hz, 1H), 3.76 (t, J = 4.6 Hz, 2H), 3.61 (q, J = 6.6 Hz, 2H), 3.00 (q, J = 7.3 Hz, 1H), 1.45 (q, J = 6.8 Hz, 2H), 1.22 (s, 19H), 1.12 (t, J = 7.5Hz, 6H), 0.85 (t, J = 6.6 Hz, 3H).MS m / z =576.2[MH] + .

[0093] Example 12: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentyl-2-yl]methoxy}[2-(octanoyloxy)ethoxy]phosphonic acid A12 (mch-2318)

[0094] Compound A12 was prepared using compound 8a-10 as a starting material, referring to the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.26%. 1 H NMR (400 MHz, DMSO- d 6) δ 7.59 – 7.23 (m, 2H), 5.99 – 5.63 (m, 2H), 5.54 – 5.19 (m, 2H), 4.09 (t, J = 5.0 Hz, 2H), 4.04 (q, J = 5.5 Hz, 1H), 3.98 (s,1H), 3.90 (s, 1H), 3.81 (d, J = 7.0 Hz, 4H), 3.02 (q, J = 7.3 Hz, 1H), 2.28 (t, J =7.5 Hz, 2H), 1.48 (q, J = 7.3 Hz, 2H), 1.24 (d, J = 8.6 Hz, 8H), 1.13 (dd, J =15.1, 6.6 Hz, 6H), 0.87 – 0.81 (m, 3H).MS m / z =580.1[M+H] + .

[0095] Example 13: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentyl-2-yl]methoxy}(octyloxy)phosphonic acid A13 (mch-2321)

[0096] Compound A13 was prepared using compound 8a-10 as a starting material, referring to the preparation of A1 in Example 1. It was a white solid with an overall yield of 5.36%. 1 H NMR (400 MHz, DMSO- d 6) δ 8.26 (d, J = 5.5 Hz, 1H), 7.65 – 7.36 (m,1H), 5.85 (dd, J = 64.3, 7.1 Hz, 1H), 5.69 (dd, J = 32.1, 6.5 Hz, 1H), 4.03 (q, J=5.8 Hz, 1H), 3.98 (dd, J = 5.3, 3.1 Hz, 1H), 3.95 – 3.88 (m, 1H), 3.81 (s, 2H), 3.65 (s, 2H), 2.80 (dd, J = 14.6, 7.2 Hz, 3H), 1.54 – 1.42 (m, 2H), 1.26 – 1.20(m, 10H), 1.09 (dd, J = 9.9, 7.1 Hz, 7H), 0.87 – 0.81 (m, 3H).MS m / z =522.2[M+H] + .

[0097] Example 14: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentyl-2-yl]methoxy}[3-(hexadecyloxy)propoxy]phosphonic acid A14 (mch-2322)

[0098] Compound A14 was prepared using compound 8a-10 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 5.89%. 1 H NMR (400 MHz, DMSO- d 6) δ 7.38 (d, J = 8.2 Hz, 1H), 5.87 (dd, J = 69.4, 6.9 Hz, 1H), 5.73 (dd, J = 12.4, 6.6 Hz, 1H), 5.46 (s, 1H), 4.01 (dq, J = 8.9, 4.4 Hz, 2H), 3.91 (d, J = 16.5 Hz, 2H), 3.78 (s, 2H), 3.38 (s, 4H), 3.28 (d, J =13.2 Hz, 2H), 2.89 – 2.65 (m, 1H), 1.72 (h, J = 6.6 Hz, 2H), 1.49 – 1.38 (m,2H), 1.22 (d, J = 4.0 Hz, 27H), 1.11 (dd, J= 9.1, 6.8 Hz, 6H), 0.89 – 0.81 (m,3H). Example 15: {3-[3-(3-butoxypropoxy)propoxy]propoxy} ({[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy})phosphonic acid A15 (mch-2350)

[0099] Compound A15 was prepared using compound 8a-10 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 5.81%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.85 (s, 1H), 7.46 (d, J = 54.0 Hz, 1H),6.07 – 5.73 (m, 1H), 5.54 (d, J = 103.6 Hz, 2H), 4.17 (s, 1H), 4.02 (s, 2H), 3.90 (d, J = 17.3 Hz, 3H), 3.52 – 3.24 (m, 15H), 2.81 (p, J = 6.9 Hz, 1H), 1.45(p, J = 6.7 Hz, 2H), 1.29 (ddt, J = 13.0, 7.8, 4.2 Hz, 2H), 1.12 (dd, J = 9.2, 6.9Hz, 6H), 1.03 (dt, J = 6.4, 3.0 Hz, 6H), 0.86 (t, J = 7.3 Hz, 3H).MS m / z =639.7[M+H] + .

[0100] Example 16: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentyl-2-yl]methoxy}[2-(hexanoyloxy)ethoxy]phosphonic acid A16 (mch-2401)

[0101] Compound A16 was prepared using compound 8a-10 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.82%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.00 (d, J = 116.8 Hz, 1H), 7.39 (d, J = 8.2Hz, 1H), 5.87 (dd, J = 72.1, 7.0 Hz, 1H), 5.77 – 5.05 (m, 3H), 4.11 (d, J = 5.0Hz, 2H), 3.96 (dd, J = 45.1, 19.6 Hz, 7H), 2.86 (d, J = 11.7 Hz, 1H), 2.27 (t, J =7.5 Hz, 2H), 1.50 (p, J = 7.4 Hz, 2H), 1.28 – 1.20 (m, J = 4.1, 3.4 Hz, 4H), 1.11(dd, J = 6.0, 2.8 Hz, 6H), 0.84 (t, J = 6.7 Hz, 3H). Example 17: (2-Butoxypropoxy)({[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy})phosphonic acid A17 (mch-3329)

[0102] Compound A17 was prepared using compound 8a-10 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 2.36%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.84 (s, 1H), 9.39 (s, 1H), 7.45 (d, J =7.9 Hz, 1H), 5.75 (dd, J = 14.1, 5.8 Hz, 2H), 5.62 (d, J = 8.1 Hz, 1H), 5.48 (d, J= 8.1 Hz, 1H), 5.30 (d, J = 5.7 Hz, 2H), 4.23 – 4.06 (m, 2H), 3.98 (s, 1H), 3.89 (s, 1H), 3.78 (s, 2H), 3.17 (t, J = 4.6 Hz, 2H), 1.50 – 1.42 (m, 2H), 1.27 – 1.23 (m, 3H), 1.14 – 1.08 (m, 9H), 0.86 (td, J = 7.5, 4.8 Hz, 3H).MS m / z =524.1[M+H] + .

[0103] Example 18: ({1-[(1-butoxypropyl-2-yl)oxy]propyl-2-yl}oxy)({[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(2-methylpropionyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxacyclopentan-2-yl]methoxy})phosphonic acid A18 (mch-3331)

[0104] Compound A18 was prepared using compound 8a-10 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 2.19%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.98 (d, J = 113.9 Hz, 1H), 7.66 – 7.34 (m,1H), 6.06 – 5.72 (m, 1H), 5.63 (d, J = 8.2 Hz, 1H), 5.34 (d, J = 6.0 Hz, 2H), 4.11 (s, 1H), 4.05 (q, J = 5.4 Hz, 1H), 3.99 (s, 1H), 3.90 (s, 1H), 3.81 (d, J =5.7 Hz, 2H), 3.55 – 3.46 (m, 3H), 2.96 (s, 2H), 1.45 (dd, J = 7.7, 4.9 Hz, 2H),1.26 – 1.22 (m, 3H), 1.16 – 1.10 (m, 13H), 1.03 (ddt, J= 6.2, 4.6, 2.4 Hz,3H), 0.88 – 0.84 (m, 2H).MS m / z =582.2[M+H] + .

[0105] Example 19: {3-[3-(3-butoxypropoxy)propoxy]propoxy} ({[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy})phosphonic acid A19 (mch-2241)

[0106] Compound A19 was prepared using compound 5a as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 6.29%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.03 (d, J = 113.0 Hz, 1H), 7.39 (t, J = 8.9Hz, 1H), 5.84 – 5.63 (m, 2H), 5.46 (d, J = 4.9 Hz, 2H), 4.19 (s, 1H), 4.09 –3.73 (m, 6H), 3.47 (tdd, J = 24.8, 11.1, 6.2 Hz, 5H), 3.35 – 3.14 (m, 6H), 3.01– 2.94 (m, 1H), 2.40 (dt, J = 23.7, 7.4 Hz, 2H), 1.53 (t, J = 7.0 Hz, 2H), 1.45(q, J = 7.4, 7.0 Hz, 2H), 1.24 (q, J = 4.5, 3.5 Hz, 15H), 1.14 (d, J = 7.3 Hz, 3H), 1.02 (dd, J = 6.4, 4.2 Hz, 6H), 0.85 (td, J = 7.2, 3.9 Hz, 6H). Example 20: {[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}[3-(hexadecyloxy)propoxy]phosphonic acid A20 (mch-2310)

[0107] Compound A20 was prepared using compound 8a-21 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 5.87%. 1 H NMR (400 MHz, Chloroform- d ) δ 5.84 – 5.70 (m, 2H), 5.41 (s, 2H), 4.14 – 3.73 (m, 12H), 1.72 (d, J = 6.7 Hz, 2H), 1.44 (s, 6H), 1.23 (d, J = 4.5Hz, 42H), 0.85 (s, 6H). Example 21: [3-(3-butoxypropoxy)propoxy]({[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy})phosphonic acid A21 (mch-2247)

[0108] Compound A21 was prepared using compound 8a-21 as a starting material, referring to the preparation of A1 in Example 1. It was a white solid with an overall yield of 4.31%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.03 (d, J = 111.4 Hz, 1H), 7.40 (s, 1H), 5.98 – 5.60 (m, 2H), 5.45 (d, J = 5.0 Hz, 2H), 4.18 (s, 1H), 4.02 (d, J = 15.9Hz, 2H), 3.96 – 3.76 (m, 3H), 3.51 (dq, J = 13.3, 6.6 Hz, 2H), 3.34 – 3.13 (m,5H), 3.00 (q, J= 7.3 Hz, 3H), 2.46 – 2.35 (m, 2H), 1.60 – 1.47 (m, 2H), 1.43(dtd, J = 9.8, 6.7, 3.9 Hz, 2H), 1.23 (d, J = 3.4 Hz, 13H), 1.16 (d, J = 7.3 Hz, 6H), 1.04 – 0.99 (m, 3H), 0.88 – 0.82 (m, 6H). Example 22: {[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}(octyloxy)phosphonic acid A22 (mch-2238)

[0109] Compound A22 was prepared using compound 8a-21 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.49%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.83 (s, 1H), 7.39 (d, J = 8.2 Hz, 1H),5.88 – 5.64 (m, 2H), 5.58 – 5.29 (m, 2H), 4.05 – 3.79 (m, 6H), 3.70 (s, 2H),2.43 (t, J = 7.4 Hz, 2H), 1.50 (ddd, J = 21.1, 12.6, 6.5 Hz, 4H), 1.23 (q, J = 7.0, 6.5 Hz, 24H), 1.00 (t, J = 7.2 Hz, 2H), 0.86 – 0.81 (m, 6H).MS m / z =656.1[M+Na] + .

[0110] Example 23: {[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}(dodecyloxy)phosphonic acid A23 (mch-2787)

[0111] Compound A23 was prepared using compound 8a-21 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.34%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.98 (d, J = 114.7 Hz, 1H), 9.68 (d, J =227.7 Hz, 1H), 7.22 (dd, J = 147.8, 8.3 Hz, 1H), 5.96 – 5.71 (m, 1H), 5.56 (dd, J = 58.6, 8.0 Hz, 1H), 5.32 (d, J = 49.3 Hz, 2H), 4.01 (dt, J = 20.4, 6.7 Hz, 2H), 3.88 (d, J = 16.1 Hz, 1H), 3.80 (s, 2H), 3.64 (s, 2H), 2.43 (t, J = 7.4 Hz, 1H), 2.28 (t, J = 7.4 Hz, 1H), 1.49 (dt, J = 20.5, 6.7 Hz, 4H), 1.24 (p, J = 4.8, 4.0Hz, 34H), 0.89 – 0.79 (m, 6H). Example 24: Butoxyphosphonic acid A24 (mch-2793) ({[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxacyclopentan-2-yl]methoxy})

[0112] Compound A24 was prepared using compound 8a-21 as the starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.88%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.99 (d, J = 112.3 Hz, 1H), 7.67 – 7.29 (m,1H), 5.77 – 5.62 (m, 1H), 5.43 (d, J= 5.4 Hz, 1H), 4.03 (t, J = 5.4 Hz, 1H), 3.98 (t, J = 4.3 Hz, 1H), 3.90 (d, J = 3.6 Hz, 1H), 3.80 (s, 1H), 3.66 (d, J = 7.0Hz, 1H), 3.04 – 2.99 (m, 3H), 2.43 (t, J = 7.5 Hz, 2H), 1.53 (s, 1H), 1.49 –1.40 (m, 2H), 1.29 – 1.16 (m, 21H), 0.85 (td, J = 7.2, 2.7 Hz, 6H).MS m / z =578.2[M+H] + .

[0113] Example 25: {[(2R,3S,4R,5R)-5-{4-[(dodecyloxy)amino]-2-oxo-1,2-dihydropyrimidin-1-yl}-3,4-dihydroxyoxopentane-2-yl]methoxy}({2-[(4-methylpentanoyl)oxy]ethoxy})phosphonic acid A25 (mch-2795)

[0114] Compound A25 was prepared using compound 8a-21 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.56%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.30 – 10.70 (m, 1H), 7.56 – 7.27 (m,1H), 5.79 – 5.66 (m, 1H), 5.45 (dd, J = 46.8, 6.9 Hz, 2H), 4.10 (t, J = 5.0 Hz,2H), 4.04 – 3.97 (m, 1H), 3.91 (d, J = 3.6 Hz, 1H), 3.82 (s, 2H), 3.03 (q, J =7.3 Hz, 3H), 2.43 (t, J = 7.5 Hz, 1H), 2.28 (td, J = 7.8, 1.6 Hz, 2H), 1.51 (dtd, J= 13.2, 7.1, 6.6, 3.2 Hz, 3H), 1.41 (ddd, J = 10.9, 7.5, 5.7 Hz, 2H), 1.29 –1.16 (m, 19H), 0.84 (dd, J = 6.6, 2.6 Hz, 9H).MS m / z =664.3[M+H] + .

[0115] Example 26: Butoxyphosphonic acid A26 (mch-3347) ({[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(4-methylpentanoyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy})

[0116]

[0117] Compound A26 was prepared using compound 5a as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.44%. (dd, J = 59.8, 8.3 Hz, 1H), 5.42 – 5.31 (m, 1H), 4.03 (t, J = 5.7 Hz, 1H), 3.97 (d, J = 6.1 Hz, 1H), 3.91 (d, J = 3.6 Hz, 1H), 3.80 (s, 1H), 3.66 (q, J = 6.8Hz, 2H), 3.00 (d, J = 7.3 Hz, 3H), 1.49 – 1.42 (m, 3H), 1.27 (dt, J = 14.6, 3.3Hz, 2H), 1.16 (t, J = 7.3 Hz, 7H), 0.87 (dd, J = 6.9, 4.2 Hz, 6H).MS m / z =494.2[M+H] + .

[0118] Example 27: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-(4-{[(4-methylpentanoyl)oxy]amino}-2-oxo-1,2-dihydropyrimidin-1-yl)oxopentane-2-yl]methoxy}(octoxy)phosphonic acid A27 (mch-3355)

[0119] Compound A27 was prepared using compound 8a-30 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 4.17%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.88 (s, 1H), 7.48 (dd, J = 61.7, 8.3 Hz,1H), 6.02 – 5.74 (m, 1H), 5.74 – 5.59 (m, 1H), 5.55 – 5.35 (m, 1H), 4.03 (t, J = 5.5 Hz, 1H), 3.96 (d, J = 5.1 Hz, 1H), 3.88 (dd, J = 16.4, 3.6 Hz, 1H), 3.79(s, 1H), 3.61 (dd, J = 16.2, 9.5 Hz, 2H), 2.99 (d, J = 7.3 Hz, 3H), 2.45 (t, J =7.7 Hz, 1H), 1.47 (tt, J = 15.4, 6.7 Hz, 4H), 1.16 (t, J = 7.2 Hz, 8H), 0.86 (dd, J = 16.7, 6.4 Hz, 9H).MS m / z =522.2[M+H] + .

[0120] Example 28: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxacyclopentan-2-yl]methoxy}(octyloxy)phosphonic acid A28 (mch-3389)

[0121] Compound A28 was prepared using compound 5a as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.64%.1 H NMR (400 MHz, DMSO- d 6) δ 11.01 (d, J = 113.4 Hz, 1H), 7.40 (d, J = 8.3Hz, 1H), 6.02 – 5.70 (m, 1H), 5.69 – 5.21 (m, 2H), 4.08 – 3.94 (m, 2H), 3.81(d, J = 6.8 Hz, 1H), 3.66 (s, 2H), 3.02 (d, J = 7.3 Hz, 4H), 1.47 (q, J = 6.8 Hz,2H), 1.24 – 1.17 (m, 13H), 1.05 (t, J = 7.5 Hz, 2H), 0.85 (td, J = 6.9, 2.5 Hz,3H).MS m / z =506.1[MH] + .

[0122] Example 29: [3-(3-butoxypropoxy)propoxy]({[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxacyclopentan-2-yl]methoxy})phosphonic acid A29 (mch-3391)

[0123] Compound A29 was prepared using compound 8a-32 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 4.12%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.01 (d, J = 113.0 Hz, 1H), 7.67 – 7.03 (m,1H), 6.10 – 5.59 (m, 1H), 5.59 – 5.31 (m, 2H), 4.14 (s, 1H), 4.08 – 3.94 (m,2H), 3.85 (d, J = 19.2 Hz, 2H), 3.50 (dq, J = 13.6, 6.0, 5.4 Hz, 3H), 3.24 (tt, J =10.0, 4.2 Hz, 3H), 3.00 (q,J = 7.3 Hz, 4H), 2.43 (dd, J = 16.1, 8.5 Hz, 1H), 1.43 (dq, J = 12.4, 5.9, 5.4 Hz, 2H), 1.33 – 1.26 (m, 2H), 1.16 (q, J = 6.6, 5.9Hz, 7H), 1.03 (dd, J = 7.0, 2.7 Hz, 3H), 0.86 (td, J = 7.3, 1.9 Hz, 3H).MS m / z =566.1[MH] + .

[0124] Example 30: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxacyclopentan-2-yl]methoxy}[3-(hexadecyloxy)propoxy]phosphonic acid A30 (mch-3397)

[0125] Compound A30 was prepared using compound 8a-32 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 2.86%. 1 H NMR (400 MHz, DMSO- d 6) δ 10.42 (d, J = 351.1 Hz, 1H), 7.46 – 7.16 (m,1H), 5.75 (dd, J = 13.7, 6.1 Hz, 1H), 5.58 (dd, J = 61.8, 8.2 Hz, 1H), 5.47 –5.24 (m, 2H), 4.08 – 3.94 (m, 2H), 3.88 (d, J = 16.2 Hz, 1H), 3.79 (s, 2H), 3.70 (s, 2H), 3.02 (q, J = 7.2 Hz, 5H), 1.72 (q, J = 6.6 Hz, 2H), 1.45 (s, 2H), 1.23 (s, 29H), 1.04 (t, J = 7.4 Hz, 2H), 0.85 (t, J= 6.6 Hz, 3H).MS m / z =678.3[M+H] + .

[0126] Example 31: {3-[3-(3-butoxypropoxy)propoxy]propoxy} ({[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxacyclopentan-2-yl]methoxy})phosphonic acid A31 (mch-3399)

[0127] Compound A31 was prepared using compound 8a-32 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 2.12%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.00 (d, J = 113.0 Hz, 1H), 7.66 – 7.20 (m,1H), 5.86 (dd, J = 72.7, 7.1 Hz, 1H), 5.69 (dd, J = 35.8, 7.0 Hz, 1H), 5.58 –5.26 (m, 2H), 4.12 (s, 1H), 4.07 – 3.89 (m, 2H), 3.82 (s, 2H), 3.67 – 3.42(m, 4H), 3.35 – 3.13 (m, 7H), 3.01 (q, J = 7.3 Hz, 3H), 2.43 (dd, J = 16.2, 8.5Hz, 1H), 1.44 (q, J = 6.9 Hz, 1H), 1.34 – 1.25 (m, 2H), 1.16 (dt, J = 11.3, 6.3Hz, 6H), 1.03 (td, J = 8.5, 6.9, 4.9 Hz, 6H), 0.86 (t, J = 7.3 Hz, 3H).MS m / z =626.2[M+H] + .

[0128] Example 32: Butoxyphosphonic acid A32 (mch-3706) ({[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxopentyl-2-yl]methoxy})

[0129] Compound A32 was prepared using compound 8a-32 as the starting material, referring to the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.46%. 1 H NMR (400 MHz, DMSO- d 6) δ 11.01 (d, J = 112.7 Hz, 1H), 7.67 – 6.87 (m,1H), 6.07 – 5.59 (m, 1H), 5.59 – 5.29 (m, 1H), 4.03 (t, J = 5.6 Hz, 1H), 3.97(s, 1H), 3.94 – 3.84 (m, 1H), 3.79 (s, 1H), 3.65 (q, J = 6.9 Hz, 1H), 2.99 (q, J = 7.3 Hz, 4H), 2.47 – 2.37 (m, 1H), 1.55 – 1.41 (m, 2H), 1.30 (ddd, J = 15.6,9.6, 3.9 Hz, 2H), 1.17 (d, J = 7.3 Hz, 4H), 1.05 (t, J = 7.5 Hz, 2H), 0.86 (t, J =7.3 Hz, 2H).MS m / z =452.1[M+H] + .

[0130] Example 33: {[(2R,3S,4R,5R)-3,4-dihydroxy-5-{2-oxo-4-[(propionyloxy)amino]-1,2-dihydropyrimidin-1-yl}oxacyclopentan-2-yl]methoxy}[(4-methylpentyl)oxy]phosphonic acid A33 (mch-3707)

[0131] Compound A33 was prepared using compound 8a-32 as a starting material, following the preparation of A1 in Example 1. It was a white solid with an overall yield of 3.74%. 1 H NMR (400 MHz, DMSO-d 6) δ 11.22 – 10.80 (m, 1H), 7.44 (d, J = 8.2 Hz,1H), 6.04 – 5.59 (m, 1H), 5.54 – 5.25 (m, 2H), 4.09 – 4.00 (m, 1H), 3.97 (s,1H), 3.89 (s, 1H), 3.76 (s, 1H), 3.59 (d, J = 7.0 Hz, 2H), 3.03 (s, 3H), 1.51 –1.43 (m, 2H), 1.15 (d, J = 7.5 Hz, 6H), 1.05 (t, J = 7.4 Hz, 2H), 0.84 (d, J = 6.6Hz, 6H).MS m / z =480.1[M+H] + .

[0132] Test Implementation Examples 1.1 Experimental strains and cells: Recombinant vesicular stomatitis virus (VSV-GFP) was stored at the Biomedical Analysis Center of the Academy of Military Medical Sciences. All experimental procedures in this study were performed in a biosafety level 2 laboratory. Human metapneumovirus (HMPV-A2-GFP-NS1) was stored at Zhejiang Difuluns Biotechnology Co., Ltd.

[0133] Human coronavirus OC43 (HCoV-OC43) was preserved at Zhejiang Difuluns Biotechnology Co., Ltd.

[0134] Respiratory syncytial virus (RSV-GFP1(A2)) was stored at Zhejiang Difuluns Biotechnology Co., Ltd.

[0135] Madin-Darby canine kidney (MDCK) cells are preserved in the Vector Biology and Biosafety Protection Laboratory of the Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences.

[0136] African green monkey kidney cells (Vero) are preserved at the Biomedical Analysis Center of the Academy of Military Medical Sciences.

[0137] Rhesus monkey kidney epithelial cells (LLC-MK2) were obtained from the Cell Bank of the Chinese Academy of Sciences.

[0138] Human malignant embryonic rhabdomyosarcoma cells (RD) were obtained from the Cell Bank of the Chinese Academy of Sciences.

[0139] Human laryngeal epidermoid carcinoma cells (Hep-2) were obtained from the Cell Bank of the Chinese Academy of Sciences.

[0140] 1.2 Experimental Reagents and Consumables

[0141] 1.3 Main Experimental Instruments

[0142] Test Example 1: Cytotoxicity Assay Cells: MDCK cells; Culture medium: DMEM medium + FBS (10%) + antibiotics (1%) (1. MDCK cells were cultured in DMEM medium supplemented with 10% fetal bovine serum and 1% penicillin-dextrose antibody. The cells were digested, centrifuged, resuspended, counted, and prepared to a concentration of 8×10⁶ cells / mL.) 4 Prepare a cell suspension of 100 μL / ml and add it to each well of a 96-well plate (100 μL per well), i.e., 8 × 10⁸ cells per well. 3 Each cell.

[0143] (2. Place the prepared 96-well plate in a constant temperature incubator at 37℃ and 5% CO2 for 24 hours.)

[0144] (3. After the cells attach, discard the old culture medium and add 100 μL of drug-containing culture medium of different concentrations to each well. Set up three replicates for each sample group, and set up blank control and positive control group. Place the 96-well plate with added drug into the cell culture incubator and culture for 24 h.

[0145] (4. Prepare the required amount of blank culture medium containing 1:5 MTS, discard the old culture medium, add 100 μL of the above culture medium to each well for staining, and continue to incubate in the incubator for 1.5 h.

[0146] (5. Subsequently, the OD value of each well was measured at a wavelength of 450 nm using a microplate reader, and cell viability was calculated. The results are shown in Table 1.) Test Example 2: Anti-VSV Virus Experiment Cells: MDCK cells; Virus: VSV-GFP Culture medium: DMEM medium + FBS (10%) + antibiotics (1%) Operating instructions: (1. MDCK cells were cultured in DMEM medium supplemented with 10% fetal bovine serum and 1% penicillin-dextrose antibody. The cells were digested, centrifuged, resuspended, counted, and prepared to a concentration of 8×10⁶ cells / mL.) 4 Prepare a cell suspension of 100 μL / ml and add it to each well of a 96-well plate (100 μL per well), i.e., 8 × 10⁸ cells per well. 3 Each cell.

[0147] (2. Place the prepared 96-well plate in a constant temperature incubator at 37℃ and 5% CO2 for 24 hours.)

[0148] (3. After the cells attach, discard the old culture medium and add 100 μL of drug-containing culture medium of different concentrations to each well. Set up three replicates for each sample group, and set up blank control and negative control group. Place the 96-well plate with added drug into a cell culture incubator for culture.

[0149] (4. Perform VSV-GFP virus infection with a multiplicity of infection (MOI) of 1 and continue culturing for 24 hours.)

[0150] (5. Aspirate the culture medium containing the virus and drugs, add Hochest (5000*) prepared with physiological saline, and incubate in an incubator for 15 min.

[0151] (6. Use a high-content instrument to read the OD value.)

[0152] (7. Data Processing: Inhibition rate (%) = (OD value of drug-treated wells - OD value of viral wells) / (OD value of NT wells - OD value of viral wells) × 100% Table 1. Cytotoxicity results of the compounds in the examples.

[0153] Table 2 shows the anti-VSV virus results of the compounds in the examples.

[0154] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. The diester prodrug of N-hydroxycytidine phosphate as shown in Formula I and its pharmaceutically acceptable salt, Formula I in: R1 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C13 straight-chain or branched alkyl ester, C2-C13 straight-chain or branched alkenyl ester, C2-C13 straight-chain or branched alkynyl ester, C6-C18 aryl, C1-C6 straight-chain or branched alkyl, C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide. R2 is selected from C1-C25 straight-chain or branched alkyl, C2-C25 straight-chain or branched alkenyl, C2-C25 straight-chain or branched alkynyl, C3-C25 straight-chain or branched alkyl containing 1-4 oxygen atoms (-O-), C3-C25 straight-chain or branched alkyl ester, C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1 -C25 straight-chain or branched alkyl amide group, C2-C25 straight-chain or branched alkenyl amide group, C2-C25 straight-chain or branched alkynyl amide group, wherein in C3-C25 straight-chain or branched alkyl groups containing 1-4 oxygen groups (-O-), the oxygen group may be located at any position on the alkyl chain as long as the valence allows; in C3-C25 straight-chain or branched alkyl ester group, the ester group (-COO-) may be located at any position on the alkyl chain as long as the valence allows.

2. The diester prodrug of N-hydroxycytidine phosphate as described in Formula I according to claim 1, and its pharmaceutically acceptable salt, characterized in that, Preferably, R1 is selected from C1-C15 straight-chain or branched alkyl, C2-C15 straight-chain or branched alkenyl, C2-C15 straight-chain or branched alkynyl, C1-C13 straight-chain or branched alkyl ester, C2-C13 straight-chain or branched alkenyl ester, C2-C13 straight-chain or branched alkynyl ester, C6-C10 aryl, C1-C6 straight-chain or branched alkyl, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C15 straight-chain or branched alkylamide, C2-C15 straight-chain or branched alkenylamide, and C2-C15 straight-chain or branched alkynylamide. Preferably, R1 is selected from C1-C11 straight-chain or branched alkyl, C2-C11 straight-chain or branched alkenyl, C2-C11 straight-chain or branched alkynyl, C6-C10 aryl, C1-C3 straight-chain or branched alkyl, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O or N, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O or N, C1-C11 straight-chain or branched alkylamide, C2-C11 straight-chain or branched alkenylamide, and C2-C11 straight-chain or branched alkynylamide. Preferably, R1 is selected from C1-C11 straight-chain or branched alkyl groups; Preferably, R2 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-4 oxygen atoms (-O-), C3-C20 straight-chain or branched alkyl ester, C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, and 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S. C1-C20 straight-chain or branched alkyl amide groups, C2-C20 straight-chain or branched alkenyl amide groups, C2-C20 straight-chain or branched alkynyl amide groups, wherein in C3-C20 straight-chain or branched alkyl groups containing 1-4 oxygen groups (-O-), the oxygen group can be located at any position in the alkyl chain as long as the valence allows; in C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position in the alkyl chain as long as the valence allows; Preferably, R2 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-4 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl containing 1-4 oxygen groups (-O-), the oxygen group can be located at any position in the alkyl chain as long as the chemical valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position in the alkyl chain as long as the chemical valence allows. Preferably, R2 is selected from C1-C10 straight-chain or branched alkyl, C2-C10 straight-chain or branched alkenyl, C2-C10 straight-chain or branched alkynyl, C3-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), the oxygen group can be located at any position in the alkyl chain as long as the chemical valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position in the alkyl chain as long as the chemical valence allows. Preferably, R2 is selected from C1-C10 straight-chain or branched alkyl groups, C3-C20 straight-chain or branched alkyl groups containing 1-3 oxygen groups (-O-), and C3-C20 straight-chain or branched alkyl ester groups. Among the C3-C20 straight-chain or branched alkyl groups containing 1-3 oxygen groups (-O-), the oxygen group can be located at any position on the alkyl chain, provided that the chemical valence allows. Among the C3-C20 straight-chain or branched alkyl ester groups, the ester group (-COO-) can be located at any position on the alkyl chain, provided that the chemical valence allows.

3. The diester prodrug of N-hydroxycytidine phosphate as described in Formula I according to claim 1, and its pharmaceutically acceptable salt, characterized in that, It is represented by the following formula I-1 or I-2: Wherein, the definition of substituent R1 is the same as that in claim 1 or 2; R21 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C1-C20 straight-chain or branched alkyl substituted with oxo groups (O=), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows; R22 is selected from C1-C20 straight-chain or branched alkyl, C2-C20 straight-chain or branched alkenyl, C2-C20 straight-chain or branched alkynyl, C1-C20 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 to 3 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 to 3 heteroatoms selected from O, N, and S, C1-C20 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain, provided that the valence allows; n is an integer from 1 to 6.

4. The diester prodrug of N-hydroxycytidine phosphate as described in Formula I according to claim 3, and its pharmaceutically acceptable salt, characterized in that, Preferably, R21 is selected from C1-C18 straight-chain or branched alkyl, C2-C18 straight-chain or branched alkenyl, C2-C18 straight-chain or branched alkynyl, C1-C18 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C1-C10 straight-chain or branched alkyl substituted with oxo groups (O=), C6-C18 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C18 straight-chain or branched alkylamide, C2-C18 straight-chain or branched alkenylamide, and C2-C18 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain as long as the valence allows; Preferably, R21 is selected from C1-C18 straight-chain or branched alkyl groups, C1-C18 straight-chain or branched alkyl groups containing 1 or 2 oxygen groups (-O-), and C1-C10 straight-chain or branched alkyl groups substituted with oxo groups (O=), wherein the oxygen group is located at any position on the alkyl chain, provided that the valence allows it. Preferably, R22 is selected from C1-C18 straight-chain or branched alkyl, C2-C18 straight-chain or branched alkenyl, C2-C18 straight-chain or branched alkynyl, C1-C18 straight-chain or branched alkyl containing 1-3 oxygen groups (-O-), C6-C10 aryl, 5- to 10-membered heterocyclic alkyl containing 1 or 2 heteroatoms selected from O, N, and S, 5- to 10-membered heteroaryl containing 1 or 2 heteroatoms selected from O, N, and S, C1-C18 straight-chain or branched alkylamide, C2-C20 straight-chain or branched alkenylamide, and C2-C20 straight-chain or branched alkynylamide, wherein the oxygen group can be located at any position on the alkyl chain as long as the valence allows; Preferably, R22 is selected from C1-C18 straight-chain or branched alkyl groups, C1-C18 straight-chain or branched alkyl groups containing 1 or 2 oxygen groups (-O-), wherein the oxygen group can be located at any position on the alkyl chain as long as the chemical valence allows; Preferably, n is an integer from 1 to 4; Preferably, n is an integer of 1, 2, or 3.

5. The diester prodrug of N-hydroxycytidine phosphate according to any one of claims 1 to 4, and its pharmaceutically acceptable salt thereof, are selected from specific compounds A1 to A33 with the following structures:

6. The diester prodrug of N-hydroxycytidine phosphate as described in any one of claims 1 to 5, and its pharmaceutically acceptable salt, characterized in that, The pharmaceutically acceptable salt is a base addition salt of a compound of formula I, wherein the base used for salt formation includes inorganic bases and organic bases, and the inorganic salts include: sodium salts, potassium salts, lithium salts, and barium salts; the organic salts include: amine salts, triethylamine salts, and pyridine salts.

7. A method for preparing the diester prodrug of N-hydroxycytidine phosphate as described in any one of claims 1 to 6, and its pharmaceutically acceptable salt thereof: As shown in the reaction formula above, the method includes the following steps: i-1) Compound 1a is protected with silane and then undergoes a one-pot reaction involving chlorination and amine substitution to generate compound 2a. i-2) Compound 2a undergoes an acetone cross condensation reaction to generate compound 3a. i-3) Compound 3a undergoes a silane protection reaction to regenerate compound 4a. i-4) Compound 4a undergoes an amine substitution reaction to generate compound 5a. i-5) Compound 5a is restructured through condensation and other reactions to generate compound 6a with the corresponding R1 group. i-6) Compound 6a undergoes a deprotection reaction of the silyl ether protecting group to regenerate compound 7a. i-7) Compound 7a undergoes a condensation reaction to form a phosphite compound 8a. i-8) Compound 8a undergoes substitution and oxidation reactions to generate compound 9a containing the R2 group. i-9) Compound 9a undergoes a hydrolysis reaction to remove the acetone cross protection, yielding compound 10a. i-10) Compound 10a undergoes a reverse Michael addition reaction to remove the cyanoethyl group, yielding compound of general formula I; In the above reaction formula, the definitions of substituents R1 and R2 are the same as those in Formula I above; Preferably, in step i-1), trimethylchlorosilane is used as the silanization protecting agent, phosphorus oxychloride is used as the chlorination agent, and 1,2,4-triazole is used as the transition nucleophile to carry out the amine substitution reaction, and the reaction is carried out at 0~25°C. Preferably, in step i-2), sulfuric acid is used as a catalyst, and 2,2-dimethoxypropane and compound 2a undergo a condensation reaction at 25-40°C; Preferably, in step i-3), tert-butyldimethylchlorosilane is used as a silanization protecting agent, and the reaction is carried out at room temperature; Preferably, in step i-4), hydroxylamine hydrochloride is used as the final nucleophilic substitution agent to replace triazole, and the reaction is carried out at room temperature; Preferably, in step i-5), the condensation reaction is carried out using the corresponding acid or acyl chloride at room temperature; Preferably, in step i-6), tetrabutylammonium fluoride is used to remove the silane protecting group, and the reaction is carried out at room temperature; Preferably, in step i-7), N,N-diisopropylethylamine is used as an acid-binding agent for the condensation reaction, and the reaction is carried out at room temperature; Preferably, in steps i-8), a substitution reaction is carried out using the corresponding alcohol, and an oxidation reaction is carried out using tert-butylhydrogen oxidant to obtain the corresponding phosphate ester compound 9a, and the reaction is carried out at room temperature; Preferably, in step i-9), formic acid is used as a catalyst, and the reaction is carried out at room temperature; Preferably, in step i-10), triethylamine is used for a reverse Michael addition reaction, which is carried out at room temperature.

8. A pharmaceutical composition comprising a therapeutically effective amount of a diester prodrug of N-hydroxycytidine phosphate as described in any one of claims 1 to 6, of formula I, I-1 or I-2, and a pharmaceutically acceptable salt thereof, and optionally a pharmaceutically acceptable excipient.

9. Use of the diester prodrug of N-hydroxycytidine phosphate as described in any one of claims 1 to 6, and the pharmaceutically acceptable salt thereof, in the preparation of a medicament for treating viral infections; in, The viruses mentioned are RNA viruses, including coronaviruses, influenza viruses, rhabdoviruses, paramyxoviruses, respiratory syncytial viruses, flaviviridae viruses, filoviridae viruses, human metapneumoviruses, porcine epidemic diarrhea viruses, Bunyaviridae viruses, or arenaviruses.

10. The use according to claim 9, characterized in that, The viruses mentioned are influenza virus, coronavirus, respiratory syncytial virus, and human metapneumovirus.

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