Anti-SARS-cov-2 drug

Abstract

Provided is an antiviral drug that is effective against SARS-CoV-2.　Provided are: a compound represented by formula (I) (in the formula, Ar and R are as defined in the specification); a salt thereof; a solvate of these; a prodrug of these; and an anti-SARS-CoV-2 drug comprising these.

Description

Anti-SARS-CoV-2 drug

[0001] This invention relates to an anti-SARS-CoV-2 drug.

[0002] Since the global spread of COVID-19, an infectious disease caused by the novel coronavirus (SARS-CoV-2), various anti-SARS-CoV-2 drugs have been approved, including various antibody drugs, remdesivir and mornupiravir (which were repurposed from other antiviral drugs), and newly developed drugs such as nilmatrelvir and encitrelvir. Remdesivir and mornupiravir inhibit the viral RNA-dependent RNA polymerase, while nilmatrelvir and encitrelvir inhibit the main protease necessary for viral replication. However, these drugs have several drawbacks, including various side effects and problems with their use in combination with other drugs. Therefore, it is extremely important to identify and develop novel drugs with different mechanisms of action than these drugs.

[0003] There have been no reports to date regarding the relationship between 2-pyridone-3-carboxylic acid derivatives and their anti-SARS-CoV-2 effects.

[0004] The object of this invention is to provide an antiviral drug effective against SARS-CoV-2.

[0005] To solve the aforementioned problems, the present inventors established an anti-SARS-CoV-2 assay system for drugs and proceeded with screening various drugs. As a result, they discovered that a specific 2-pyridone-3-carboxylic acid derivative has an anti-SARS-CoV-2 effect, thus completing the present invention.

[0006] In other words, the gist of the present invention is as follows: [1] Formula (I) below:

[0007] Compounds represented by (wherein Ar is a substituted or unsubstituted aromatic group, and R is a hydrogen atom, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted alkyl group), salts thereof, solvates thereof, or prodrugs thereof.

[0008] [2] In formula (I) above, Ar is a substituted or unsubstituted C １－６-an alkyl group, substituted or unsubstituted C １－６ -an alkoxy group, a halogen atom, and at least one substituent selected from the group consisting of a hydroxy group, each substituted or unsubstituted, C ６－１０ -an aromatic hydrocarbon group, or a 5- or 6-membered aromatic heterocyclic group, the compound according to [1] above, a salt thereof, a solvate thereof, or a prodrug thereof.

[0009] [3] In the formula (I), Ar is C １－６ -an alkyl group, C １－６ -an alkoxy group, a halogen atom, and one or two substituents selected from the group consisting of a hydroxy group, each substituted or unsubstituted, C ６－１０ -an aromatic hydrocarbon group, or a 5- or 6-membered aromatic heterocyclic group, the compound according to [1] above, a salt thereof, a solvate thereof, or a prodrug thereof.

[0010] [4] In the formula (I), Ar is C １－６ -an alkyl group, C １－６ -an alkoxy group, and at least one substituent selected from the group consisting of a halogen atom, each substituted or unsubstituted, C ６－１０ -an aromatic hydrocarbon group, the compound according to [1] above, a salt thereof, a solvate thereof, or a prodrug thereof.

[0011] [5] In the formula (I), R is a hydrogen atom; substituted or unsubstituted C １－６ -an alkoxy group, and at least one substituent selected from the group consisting of a halogen atom, each substituted or unsubstituted, C ６－１０ -an aromatic hydrocarbon group; or C １－６ -an alkyl group, the compound according to any one of [1] to [4] above, a salt thereof, a solvate thereof, or a prodrug thereof.

[0012] [6] In the formula (I), R is a hydrogen atom; C １－６ -an alkoxy group, and one or two substituents selected from the group consisting of a halogen atom, each substituted or unsubstituted, a phenyl group; or C １－６ -an alkyl group, the compound according to any one of [1] to [4] above, a salt thereof, a solvate thereof, or a prodrug thereof.

[0013] [7] In formula (I), R is a hydrogen atom; a phenyl group substituted with one or two substituents selected from halogen atoms; or C １－６ - Compounds described in any one of items [1] to [4] above, salts thereof, solvates thereof, or prodrugs thereof, which are alkyl groups.

[0014] [8] A pharmaceutical composition comprising a compound according to any one of items [1] to [7] above, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, and a pharmaceutically acceptable carrier. [9] An anti-SARS-CoV-2 drug comprising a compound according to any one of items [1] to [7] above, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof.

[10] The anti-SARS-CoV-2 drug according to [9] above, which does not inhibit at least one of the RNA-dependent RNA polymerase and 3CL protease of SARS-CoV-2.

[0015]

[11] A compound, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, as described in any one of [1] to [7] above, for use in the treatment or prevention of SARS-CoV-2.

[12] A method for the prevention or treatment of SARS-CoV-2, comprising administering a therapeutically effective amount of a compound, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, to a mammal, comprising administration in a mammal.

[13] Use of a compound, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, as described in any one of [1] to [7] above, for the manufacture of an anti-SARS-CoV-2 drug.

[0016] [1A] The following formula (I'):

[0017]

[0018] (wherein Ar is a substituted or unsubstituted aromatic group.) Compounds represented by the formula (I'), salts thereof, solvates thereof, or prodrugs thereof. [2A] In formula (I'), Ar is a substituted or unsubstituted C １－６ - Alkyl alkyl, substituted or unsubstituted C１－６ - The compound according to [1A], a salt thereof, a solvate thereof, or a prodrug thereof, which is a phenyl group substituted with at least one substituent selected from an alkoxy group, a halogen atom, and a hydroxyl group. [3A] An anti-SARS-CoV-2 drug comprising the compound according to [1A] or [2A], a salt thereof, a solvate thereof, or a prodrug thereof.

[0019] According to the present invention, an antiviral agent effective against SARS-CoV-2 can be provided.

[0020] Figure 1 shows a schematic of the anti-SARS-CoV-2 assay performed in the examples. Figure 2 shows the anti-SARS-CoV-2 effects of compound 5 and nilmatrelvir of the present invention in HeLa-ACE2 cells. Figure 3 shows the effect of the present invention on SARS-CoV-2 RNA-dependent RNA polymerase. Figure 4 shows the effect of the present invention on SARS-CoV-2 3CL protease.

[0021] The present invention will be described in detail below. In formulas (I) and (I'), the aromatic group is, for example, a phenyl group, a naphthyl group, etc. ６－１０ - Aromatic hydrocarbon groups (aryl groups); examples include 5- to 14-membered aromatic heterocyclic groups (preferably 5 or 6-membered aromatic heterocyclic groups) such as furyl groups, thienyl groups, pyrrolyl groups, oxazolyl groups, isoxazolyl groups, thiazolyl groups, isothiazolyl groups, imidazolyl groups, pyrazolyl groups, triazolyl groups (1,2,3-triazolyl groups, 1,2,4-triazolyl groups), pyridyl groups, pyrimidinyl groups, pyridadinyl groups, pyrazinyl groups, quinolyl groups, isoquinolyl groups, indolyl groups, pyridothienopyrimidinyl groups, etc.

[0022] Substituents in the aromatic group include linear and / or cyclic C groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, hexyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and 2-cyclopropylethyl. １－６- Alkyl groups; linear and / or cyclic C such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, hexyloxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, and cyclohexyloxy groups. １－６ - Alkoxy groups; linear and / or cyclic C groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group, isopropoxycarbonyl group, butoxycarbonyl group, isobutoxycarbonyl group, sec-butoxycarbonyl group, tert-butoxycarbonyl group, pentyloxycarbonyl group, isopentyloxycarbonyl group, cyclopropyloxycarbonyl group, cyclobutyloxycarbonyl group, cyclopentyloxycarbonyl group, etc. １－６ -Alkoxy-carbonyl group; C such as phenyl group, tolyl group, naphthyl group, etc. ６－１０ - Aromatic hydrocarbon groups (aryl groups); halogen atoms such as fluorine, chlorine, bromine, and iodine; C such as formyl, acetyl, propionyl (propanoyl), butyryl (butanoyl), valeryl (pentanoyl), and hexanoyl groups. １－６ - Aliphatic acyl groups; C such as benzoyl groups and toluyl groups ７－１１ - Aromatic acyl group (aloyl group); C ７－１６ - Aralkyl group (C ６－１０ -Aryl-C １－６ -Alkyl alkyl group), C ７－１６ - Aralkyloxy group (C ６－１０ -Aryl-C １－６ -alkoxy group), hydroxyl group, carboxyl group, amino group, C １－６ - Alkylamino group, diC １－６ - Examples include alkylamino groups.

[0023] Said C １－６ - Alkyl alkyl group, C １－６ - Alkoxy group, C １－６ -alkoxy-carbonyl group, C ６－１０ - Aromatic hydrocarbon group, C １－６ - Aliphatic acyl group, C ７－１１ - Aromatic acyl group, C７－１６ - Aralkyl group, C ７－１６ - Aralkyloxy group, C １－６ - Alkylamino group and diC １－６ - The alkylamino group is an aromatic group (for example, the above C ６－１０ - Aromatic hydrocarbon group, 5-14 member aromatic heterocyclic group), acyl group (for example, the above C １－６ - Aliphatic acyl group, C ７－１１ - Aromatic acyl group), hydroxyl group, carboxyl group, halogen atom, C １－６ - It may be substituted with one or more substituents selected from alkoxy groups (e.g., methoxy group, ethoxy group, propoxy group), etc. For example, C substituted with a halogen atom １－６ - An example of an alkyl group is the trifluoromethyl group.

[0024] In this specification, "substituted or unsubstituted" means that substitution is permitted, and unless otherwise specified, it means "unsubstituted."

[0025] In formulas (I) and (I'), Ar is a substituted or unsubstituted aromatic group. In formulas (I) and (I'), Ar is preferably a substituted or unsubstituted C, respectively. ６－１０ - An aromatic hydrocarbon group, or a five- or six-membered aromatic heterocyclic group. In formulas (I) and (I'), preferred embodiments of Ar are as follows:

[0026] In one embodiment, Ar is preferably a substituted or unsubstituted C １－６ - Alkyl alkyl groups (e.g., methyl, isopropyl), substituted or unsubstituted C １－６ -C13 is substituted with at least one substituent selected from alkoxy groups (e.g., methoxy), halogen atoms (e.g., fluorine, chlorine, bromine), and hydroxyl groups, or is unsubstituted. ６－１０ - An aromatic hydrocarbon group (e.g., phenyl, naphthyl), or a 5- or 6-membered aromatic heterocyclic group (e.g., furyl). In one embodiment, Ar is more preferably a substituted or unsubstituted C １－６ - Alkyl alkyl groups (e.g., methyl, isopropyl), substituted or unsubstituted C１－６ - A C molecule substituted with at least one substituent selected from alkoxy groups (e.g., methoxy), halogen atoms (e.g., fluorine, chlorine, bromine), and hydroxyl groups, or unsubstituted. ６－１０ - An aromatic hydrocarbon group (e.g., phenyl, naphthyl), or a 5- or 6-membered aromatic heterocyclic group (e.g., furyl). In one embodiment, Ar is more preferably C １－６ - Alkyl alkyl groups (e.g., methyl, isopropyl), C １－６ - Substituted with one or two substituents selected from alkoxy groups (e.g., methoxy), halogen atoms (e.g., fluorine, chlorine, bromine), and hydroxyl groups, or unsubstituted, C ６－１０ - An aromatic hydrocarbon group (e.g., phenyl, naphthyl), or a five- or six-membered aromatic heterocyclic group (e.g., furyl).

[0027] In one embodiment, the selectivity coefficient (SI) (50% toxicity concentration (CC) ５０ ) / 50% effective concentration (EC ５０ From the standpoint of ), Ar is preferably C １－６ - Alkyl alkyl groups (e.g., methyl, isopropyl), C １－６ - A C molecule substituted with at least one substituent selected from alkoxy groups (e.g., methoxy) and halogen atoms (e.g., chlorine atoms), or unsubstituted. ６－１０ - Aromatic hydrocarbon groups (e.g., phenyl, naphthyl). In one embodiment, from the viewpoint of SI, Ar is more preferably C １－３ - Substituted with one or two substituents selected from alkyl groups (e.g., methyl, isopropyl), methoxy groups, and chlorine atoms, or unsubstituted, C ６－１０ - An aromatic hydrocarbon group (e.g., phenyl, naphthyl). In one embodiment, from the viewpoint of SI, Ar is more preferably substituted with one or two substituents selected from a methyl group, a methoxy group, and a chlorine atom, or is unsubstituted. ６－１０ - These are aromatic hydrocarbon groups (e.g., phenyl, naphthyl).

[0028] In formula (I), R is a hydrogen atom, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted alkyl group. In formula (I), R is preferably a hydrogen atom, a substituted or unsubstituted C ６－１０ - Aromatic hydrocarbon group, or substituted or unsubstituted C １－６ - It is an alkyl group. In formula (I), preferred embodiments of R are as follows:

[0029] In one embodiment, R is preferably a hydrogen atom; substituted or unsubstituted C １－６ - A C molecule substituted with at least one substituent selected from alkoxy groups (e.g., methoxy) and halogen atoms (e.g., fluorine atom, bromine atom), or unsubstituted. ６－１０ - Aromatic hydrocarbon groups (e.g., phenyl); or C １－６ - An alkyl group (e.g., isopropyl). In one embodiment, R is more preferably a hydrogen atom; C １－６ - Phenyl groups substituted with one or two substituents selected from alkoxy groups (e.g., methoxy) and halogen atoms (e.g., fluorine atoms, bromine atoms), or unsubstituted; or C １－６ - It is an alkyl group (e.g., isopropyl).

[0030] In one embodiment, from the viewpoint of SI, R is more preferably a hydrogen atom; a phenyl group substituted with one or two substituents selected from halogen atoms (e.g., fluorine atoms); or C １－６ - It is an alkyl group (e.g., isopropyl).

[0031] The compounds of the present invention may have tautomers. The compounds of the present invention may be any isolated isomer, or they may be mixtures containing two or more isomers in any proportion.

[0032] The salt of the compound represented by formula (I) above is preferably a pharmaceutically acceptable salt, and examples include alkali metal salts such as sodium salt and potassium salt; alkaline earth metal salts such as magnesium salt and calcium salt; ammonium salts such as ammonium salt and alkylammonium salt; inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydroiodic acid, nitric acid, pyrosulfuric acid, and metaphosphoric acid; or organic acids such as citric acid, benzoic acid, acetic acid, propionic acid, fumaric acid, maleic acid, and sulfonic acid (e.g., methanesulfonic acid, p-toluenesulfonic acid, and naphthalenesulfonic acid).

[0033] Examples of solvates of the compound represented by formula (I) or its salt include hydrates.

[0034] The compound represented by formula (I), its salt, its solvates, or its prodrugs are, １ H ２ Deuterium converters converted to H(D) are also included in the present invention.

[0035] In this specification, "prodrug" refers to all compounds that, when administered to a biological system, produce a compound represented by formula (I) as a result of a spontaneous chemical reaction or by a catalyzed enzyme or metabolic reaction. Preferably, a prodrug is a compound that is acceptable for administration into the body as a pharmaceutical. Examples of prodrugs include pharmaceutically acceptable esters or amides. Specifically, examples of groups constituting a prodrug used in the hydroxyl group or amino group include C ２－７ - Acyl group, C １－６ -alkoxy(C) ２－７ -Acyl group, C １－６ - Alkoxycarbonyl (C ２－７ -Acyl group, C １－６ - Alkoxycarbonyl group, C １－６ -alkoxy(C) ２－７ -alkoxycarbonyl) group, (C ２－７ -Acyloxy)methyl group, 1-(C ２－７ -Acyloxy)ethyl group, (C ２－７ -alkoxycarbonyl)oxymethyl group, 1-[(C ２－７-alkoxycarbonyl)oxy]ethyl group and the like can be mentioned, C ２－７ -acyl group, C １－６ -alkoxycarbonyl group is preferable. Examples of the group constituting the prodrug used for the carboxyl group include, for example, C １－６ -alkyl group, C １－６ -alkoxy-C １－６ -alkyl group, (C ２－７ -acyloxy)methyl group, 1-(C ２－７ -acyloxy)ethyl group, (C ２－７ -alkoxycarbonyl)oxymethyl group, 1-[(C ２－７ -alkoxycarbonyl)oxy]ethyl group and the like can be mentioned, C １－６ -alkyl group, C １－６ -alkoxy-C １－６ -alkyl group is preferable.

[0036] Among the compounds represented by the formula (I), the compound in which R is a hydrogen atom can be produced, for example, as follows.

[0037]

[0038] (In the formula, Ar has the same meaning as in the formula (I).)

[0039] That is, the pyranone amide is obtained by reacting the cyanolactone with polyphosphoric acid under heating under solvent-free conditions. Next, hydroxylamine hydrochloride and NaHCO ３ are dissolved in an organic solvent (for example, ethanol) solution of the pyranone amide, and the mixture is reacted under heating to obtain a compound (2-pyridone-3-carboxylic acid derivative) represented by the formula (I) in which R is a hydrogen atom.

[0040] Further, the compound represented by the formula (I) in which R is a substituted or unsubstituted aromatic group or a substituted or unsubstituted alkyl group (R is not a hydrogen atom) can be produced, for example, as follows.

[0041]

[0042] That is, in the presence of a base, aromatic methyl ketone is reacted with CS２ and CH ３ By reacting with I, (1) is obtained (step i), and by reacting (1) with dimethylmalonate (DMM) under heating in the presence of a base, (2) is obtained (step ii), (2) is amidated to obtain (3) (step iii), and by reacting (3) with hydroxylamine under heating in the presence of a base, a compound represented by formula (I) in which R is not a hydrogen atom is obtained (step iv).

[0043] To purify the product obtained as described above, commonly used methods may be employed, such as column chromatography using silica gel as a support, or recrystallization using methanol, ethanol, chloroform, dimethyl sulfoxide, n-hexane-ethyl acetate, water, etc. Examples of elution solvents for column chromatography include methanol, ethanol, chloroform, acetone, hexane, dichloromethane, ethyl acetate, and mixtures thereof.

[0044] The aforementioned compounds can be formulated as anti-SARS-CoV-2 drugs in combination with conventionally accepted formulation carriers that are pharmaceutically acceptable. There are no particular limitations on the form of administration, and they can be appropriately selected and used as needed. Examples include oral preparations such as tablets, capsules, granules, fine granules, powders, sustained-release preparations, liquids, suspensions, emulsions, syrups, and elixirs, as well as parenteral preparations such as injections and suppositories.

[0045] Oral preparations are manufactured by conventional methods using, for example, starch, lactose, sucrose, mannitol, carboxymethylcellulose, inorganic salts, etc. In addition, binders, disintegrants, surfactants, lubricants, flow enhancers, flavoring agents, colorants, fragrances, etc., may be added as appropriate.

[0046] Examples of binders include starch, dextrin, gum arabic, gelatin, hydroxypropyl starch, methylcellulose, sodium carboxymethylcellulose, hydroxypropylcellulose, crystalline cellulose, ethylcellulose, polyvinylpyrrolidone, and macrogol.

[0047] Examples of disintegrants include starch, hydroxypropyl starch, sodium carboxymethylcellulose, calcium carboxymethylcellulose, carboxymethylcellulose, and low-substituted hydroxypropylcellulose.

[0048] Examples of surfactants include sodium lauryl sulfate, soy lecithin, sucrose fatty acid esters, and polysorbate 80.

[0049] Examples of lubricants include talc, waxes, hydrogenated vegetable oils, sucrose fatty acid esters, magnesium stearate, calcium stearate, aluminum stearate, and polyethylene glycol.

[0050] Examples of fluidity enhancers include light anhydrous silicic acid, dried aluminum hydroxide gel, synthetic aluminum silicate, and magnesium silicate.

[0051] The injectable preparation is manufactured according to conventional methods, and diluents such as distilled water for injection, physiological saline, glucose aqueous solution, olive oil, sesame oil, peanut oil, soybean oil, corn oil, propylene glycol, polyethylene glycol, etc., can generally be used. Furthermore, disinfectants, preservatives, stabilizers, isotonic agents, analgesics, etc., may be added as needed. Also, from the viewpoint of stability, the injectable preparation can be frozen after being filled into vials, etc., and moisture can be removed by conventional freeze-drying techniques, and the liquid preparation can be re-prepared from the freeze-dried product immediately before use. The proportion of the compound of formula (I) in the injectable preparation may vary between 5 and 50% by weight, but is not limited thereto.

[0052] Other parenteral preparations include suppositories for rectal administration, which are manufactured according to conventional methods.

[0053] Formulated anti-SARS-CoV-2 drugs can be administered, for example, one to four times a day for a period of one week to three months, although this varies depending on the dosage form and route of administration.

[0054] Furthermore, the compound represented by formula (I) does not inhibit at least one of SARS-CoV-2's RNA-dependent RNA polymerase and 3CL protease. Therefore, it is presumed that its mechanism of action differs from existing anti-SARS-CoV-2 drugs such as remdesivir and mornupiravir, which inhibit the virus's RNA-dependent RNA polymerase, and nilmatrelvir and encitrelvir, which inhibit the main protease necessary for viral replication (3CL protease in the case of coronavirus).

[0055] The anti-SARS-CoV-2 drug of the present invention is used to treat COVID-19. In the present invention, treatment also includes preventing the progression of the disease to severe symptoms.

[0056] In order for the oral preparation to exert the desired effect, the dosage will vary depending on the patient's age, weight, and the severity of the disease, but for adults, it is usually appropriate to take, for example, 0.1 to 1000 mg, preferably 1 to 500 mg, of the compound of formula (I) once or in several divided doses per day.

[0057] In order for the parenteral agent to exert the desired effect, the appropriate dosage varies depending on the patient's age, weight, and the severity of the disease, but for adults, it is usually appropriate to administer, for example, 0.1 to 1000 mg, preferably 1 to 500 mg, of the compound of formula (I) by weight, by intravenous injection, intravenous drip infusion, subcutaneous injection, or intramuscular injection.

[0058] The compound represented by formula (I), its salts, their solvates, or their prodrugs may be included in a pharmaceutical composition as the sole active ingredient, or as an ingredient in combination with other active ingredients.

[0059] Furthermore, the compound represented by formula (I), its salts, their solvates, or their prodrugs may be used in combination with other agents effective against SARS-CoV-2 infection. These may be administered separately during the course of treatment or combined with the compound represented by formula (I) in a single dosage form, such as a tablet, intravenous solution, or capsule. Examples of such other agents include remdesivir, mornupyravir, nilmatrelvir, and encitrelvir.

[0060] Coronaviruses are known to infect a variety of animals, and SARS-CoV is also known to infect a variety of animals across species barriers. Therefore, the therapeutic targets of the anti-SARS-CoV-2 drug of the present invention are not limited to humans, but include a variety of animals such as pets (e.g., dogs, cats), pigs, camels, bats, civets, tigers, ferrets, golden hamsters, minks, and sparrows.

[0061] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited thereto.

[0062] [Example 1-A] Synthesis of 2-pyridone-3-carboxylic acid derivatives (Synthesis of compounds represented by formula (I) where R is a hydrogen atom)

[0063]

[0064] The following compounds 1 to 16 were synthesized.

[0065]

[0066] (1) Synthesis of Pyranoamide Derivatives This reaction was carried out under solvent-free conditions in polyphosphate. 400 mg (approximately 1 equivalent) of each 6-aryl-4-(methylthio)-2-oxo-2H-pyran-3-carbonitrile (cyanolactone 1a-p) was heated under reflux at 170°C for 30 minutes with 15 mL of polyphosphate. After confirming the completion of the reaction by TLC, the work-up was performed. The work-up for this reaction was carried out in a 30% cold KOH solution. This solution was added dropwise to a round-bottom flask while stirring until a precipitate formed. After precipitate formation, the precipitate was filtered and purified by column chromatography. The obtained precipitate was filtered, dried, and purified. The physical properties of the obtained pyranoamide derivative 2a-p are shown below.

[0067] (1) 4-(methylthio)-2-oxo-6-phenyl-2H-pyran-3-carboxamide (2a) Brown crystals, yield: 65%; MP: 252.1℃; UV(MeOH): λmax = 340 nm. IR: (KBr) (ν, cm -1 ) 1699(amide, C=O); 1H-NMR (400 MHz, DMSO-D6) δ 8.14 (s, 1H, NH), 7.97-7.96 (d, J = 7.1 Hz, 2H), 7.55-7.53 (m, 4H, ArH & NH), 7.11 (s, 1H, CH), 2.55 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 168.09, 166.08, 160.21, 158.03, 132.9, 130.78, 129.72,129.72, 126.98, 126.98, 108.95, 101.05, 16.15; Mass: ESI-MS (m / z): [M + + Na + 284.02.

[0068] (2) 4-(methylthio)-2-oxo-6-(p-tolyl)-2H-pyran-3-carboxamide (2b) Yellow crystals, yield: 67%; MP: 248.6 ℃; UV(MeOH): λmax = 342 nm; IR: (KBr) (ν, cm -1 1691 (amide, C=O); 1 H-NMR (400 MHz, DMSO-d6) δ 8.14 (s, 1H, NH), 7.87-7.85 (d, J = 7.7 Hz, 2H, ArH), 7.52 (s, 1H, NH), 7.35-7.33 (d, J = 7.7 Hz, 2H, ArH), 7.06 (s, 1H, NH), 2.54 (s, 3H, CH3), 2.36 (s, 3H, ArH); 13 C-NMR (101 MHz, DMSO) δ 168.36, 166.14, 160.42, 158.24, 142.75, 130.32, 130.32, 127.98, 126.94, 126.94, 108.37, 100.38, 21.61, 16.36; Mass: ESI-MS (m / z): [M + + Na + 298.06.

[0069] (3) 6-(4-methoxyphenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2c) Pale reddish crystals, yield: 68%; MP: 217.6 ℃; UV (MeOH): λmax = 344, 380 nm; IR: (KBr) (ν, cm -1 1688 (amide, C=O); 1 H-NMR (400 MHz, DMSO-D6) δ8.25 (s, 1H, NH), 8.04-8.02 (d, J = 8.8 Hz, 2H, ArH), 7.59 (s, 1H, NH), 7.19-7.16 (d, J = 9.3 Hz, 2H, ArH), 7.10 (s, 1H, CH), 3.92 (s, 3H, OCH3), 2.63 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 169.20, 166.54, 162.67, 160.39, 158.18, 129.07,129.07, 123.01, 115.06,115.06, 107.32, 99.27, 56.22, 16.49; Mass: ESI-MS (m / z): [M + + Na + 314.04.

[0070] (4) 6-(4-chlorophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2d) Pale yellow crystals, yield: 65%; MP: 241.0 ℃; UV(MeOH): λmax = 348 nm; IR: (KBr) (ν, cm -1 1704 (C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 8.11 (s, 1H, NH), 7.99-7.97 (d, J = 8.2 Hz, 2H, ArH), 7.60-7.58 (m, 3H, ArH & NH), 7.12 (s, 1H, CH), 2.46 (s, 3H, CH3); 13C-NMR (101 MHz, DMSO-D6) δ 167.88, 165.98, 159.81, 156.87, 137.12, 129.32, 129.79, 129.79, 128.77, 128.77, 109.26, 101.42, 16.33; Mass: ESI-MS (m / z): [M + + Na + 318.00.

[0071] (5) 6-(4-fluorophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2e) Brown crystals, yield: 68%; MP: 223.7 ℃; UV (MeOH): λmax = 350, 386 nm; IR: (KBr) (ν, cm -1 1706 (amide C=O); 1 H-NMR (400 MHz, DMSO-D6) δ8.18 (s, 1H, NH), 8.04-8.02 (d, J = 7.7 Hz, 2H, ArH), 7.48 (m, 3H, ArH & NH), 7.28 (s, 1H, CH), 2.62 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 172.21,161.50, 157.84, 146.05, 130.66, 127.92, 127.92, 126.04,126.04, 116.98, 114.93, 99.36, 14.92.

[0072] (6) 6-(4-bromophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2f) Pale yellow crystals, yield: 65%; MP: 197.7 ℃; UV(MeOH): λmax = 346 nm; IR: (KBr) (ν, cm -1 1699 (amide C=O).

[0073] (7) 4-(methylthio)-2-oxo-6-(o-tolyl)-2H-pyran-3-carboxamide (2g) Yellow crystals, yield: 68%; MP: 186.3 ℃; UV (MeOH): λmax = 322 nm; IR: (KBr) (ν, cm -1 1690 (amide C=O).

[0074] (8) 6-(2-chlorophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2h) Brown crystals, yield: 65%; MP: 201.2 ℃; UV(MeOH): λmax = 322 nm; IR: (KBr) (ν, cm -1 1695 (amide C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 8.13 (s, 1H, NH), 7.75 (d, J = 7.7 Hz, 1H, ArH), 7.67-7.62 (m, 3H, ArH), 7.09 (s, 1H, NH), 6.98 (s, 1H, CH), 2.75 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 172.19, 167.11, 165.87, 160.37, 133.71, 133.17, 132.21, 132.00, 131.12, 128.34, 114.12, 105.11, 14.88; Mass: ESI-MS (m / z): [M + + Na + 318.00.

[0075] (9) 6-(2-methoxyphenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2i) Pale reddish crystals, yield: 68%; MP: 244.3 ℃; UV(MeOH): λmax = 320,374 nm; IR: (KBr) (ν, cm -1 1692 (amide C=O); 1H-NMR (400 MHz, DMSO-D6) δ8.23 (s, 1H, NH), 7.84-7.81 (d, J = 9.3 Hz, 1H, ArH), 7.61-7.57 (m, 2H, ArH), 7.45 (s, 1H, NH), 7.29-7.27 (d, J = 8.2 Hz, 1H, ArH), 7.18 (s, 1H, CH), 3.98 (s, 3H, OCH3), 2.51 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 168.91, 166.19, 160.69, 158.43, 155.67, 133.77, 129.84, 129.47, 121.17, 119.10, 113.30, 105.12, 56.76, 16.64; Mass: ESI-MS (m / z): [M + + Na + 314.06.

[0076] (10) 4-(methylthio)-2-oxo-6-(m-tolyl)-2H-pyran-3-carboxamide (2j) Yellow crystals, yield: 63%; MP: 250.5 ℃; UV(MeOH): λmax = 338 nm; IR: (KBr) (ν, cm -1 1692 (amide C=O).

[0077] (11) 6-(3-chlorophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2k) White crystals, yield: 67%; MP: 246.9 ℃; UV(MeOH): λmax = 339 nm; IR: (KBr) (ν, cm -1 1698 (amide C=O).

[0078] (12) 6-(3-bromophenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2l) Pale yellow crystals, yield: 68%; MP: 217.0 ℃; UV(MeOH): λmax = 336 nm; IR: (KBr) (ν, cm -11699 (amide C=O).

[0079] (13) 6-(4-isopropylphenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2m) Pale yellow crystals, yield: 66%; MP: 164.5 ℃; UV (MeOH): λmax = 338, 372 nm; IR: (KBr) (ν, cm -1 1696 (amide C=O).

[0080] (14) 4-(methylthio)-6-(naphthalen-2-yl)-2-oxo-2H-pyran-3-carboxamide (2n) White crystals, yield: 68%; MP: 249.6 ℃; UV (MeOH): λmax = 292, 378 nm; IR: (KBr) (ν, cm -1 1692 (amide C=O).

[0081] (15) 6-(2,4-dimethylphenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2o) White crystals, yield: 73%; MP: 191.6 ℃; UV (MeOH): λmax = 305 nm; IR: (KBr) (ν, cm -1 ) 1688 (C=O); Mass: ESI-MS (m / z): [M + + Na + ]

[0082] (16) 6-(2-hydroxy-4-methylphenyl)-4-(methylthio)-2-oxo-2H-pyran-3-carboxamide (2p) Brown crystals, yield: 64%; MP: 226.9 ℃; UV(MeOH): λmax = 296,374 nm; IR: (KBr) (ν, cm -1 1696 (amide C=O).

[0083] (2) Synthesis of 2-pyridone-3-carboxylic acid derivatives The reaction was carried out under reflux conditions without a catalyst in an alcohol solvent. Hydroxylamine hydrochloride (3.5 equivalents) and NaHCO3 ３ The mixture (4 equivalents) was added to 15 ml of an EtOH solution of 4-(methylthio)-2-oxo-6-phenyl-2H-pyran-3-carboxamide (2a, 400 mg, 1 equivalent), the mixture was stirred for 5 minutes, and refluxed for 12-14 hours. After confirming the completion of the reaction by TLC, the work-up was performed. The work-up for this reaction was carried out under ice-cold water conditions. After the formation of the precipitate, the precipitate was collected by filtration and purified by column chromatography.

[0084] As described above, the 2-pyridone-3-carboxylic acid derivative 3a (compound 1 of the present invention) was synthesized.

[0085] In the same manner as described above, 2-pyridone-3-carboxylic acid derivatives 3b-p (compounds 2 to 16 of the present invention) were synthesized.

[0086] The physical properties of the obtained 2-pyridone-3-carboxylic acid derivatives 3a-p (compounds 1 to 16 of the present invention) are shown below.

[0087] (1) 4-(hydroxyamino)-2-oxo-6-phenyl-1,2-dihydropyridine-3-carboxylic acid (3a) (Compound 1) Pale yellow crystals, yield: 75%; MP: 218 ℃; UV(MeOH): λmax = 302nm. IR: (KBr) (ν, cm -1 ) 1679 (C=O); 1 H-NMR (400 MHz, DMSO-D6): δ 12.65 (s, 1H), 10.39 (s, 1H), 8.42 (s, 1H), 7.88 (d, J = 7.7 Hz, 2H), 7.52 (m, 3H), 7.38 (s, 1H), 7.08 (s, 1H); 13C-NMR (101 MHz, DMSO-D6): δ 170.54, 162.72, 160.16, 159.22, 132.19, 131.27, 129.72, 129.72, 126.48, 126.48, 91.6, 82.0; HRMS calculated for ([C 12 H 10 N2O4] + H): 296.9579 found ([C 12 H 10 [N2O4] + H) + : 247.0706.

[0088] (2) 4-(hydroxyamino)-2-oxo-6-(p-tolyl)-1,2-dihydropyridine-3-carboxylic acid (3b) (Compound 2) White crystals, yield: 78%; MP: 213 ℃; UV (MeOH): λmax = 305 nm; IR: (KBr) (ν, cm -1 1680 (C=O), 1614 (C=O). 1 H-NMR (400 MHz, DMSO-D6): δ 12.60 (s, 1H, -OH), 10.34 (s, 1H, -OH), 8.40 (s, 1H, -NH), 7.77-7.75 (d, J = 7.7 Hz, 2H, ArH), 7.38-7.29 (m, J = 8.2 Hz, 3H, ArH, -NH), 7.01 (s, 1H, -CH), 2.33 (s, 3H, -CH3); 13 C-NMR (101 MHz, DMSO-D6): δ 170.54, 162.67, 160.27, 159.29, 142.37, 130.28,130.28, 128.51, 126.41,126.41, 90.85, 81.62, 21.53; Mass: MS-ESI (m / z): [M + - 1] 258.99.

[0089] (3) 4-(hydroxyamino)-6-(4-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3c) (Compound 7) Pale yellow crystals, yield: 78%; MP: 216.5 ℃; UV (MeOH): λmax = 305 nm; IR: (KBr) (ν, cm -1 1680 (C=O), 1614 (C=O).

[0090] (4) 6-(4-chlorophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3d) (Compound 10) Yellow crystals, yield: 77%; MP: 227 ℃; UV (MeOH): λmax = 308 nm; IR: (KBr) (ν, cm -1 1638 (C=O); 1 H-NMR (400 MHz, DMSO-D6): δ 12.82 (s, 1H, -OH), 10.57 (s, 1H, -OH), 8.54 (s, 1H, -NH), 8.06-8.05 (d, J = 4.4 Hz, 2H, ArH), 7.72-7.71 (d, J = 4.4 Hz, 2H, ArH), 7.53 (s, 1H, -NH), 7.26(s, 1H, -CH); 13 C-NMR (101 MHz, DMSO-D6): δ 170.64, 162.63, 159.20, 155.46, 137.00, 130.16, 129.93, 129.93, 128.51, 128.51, 92.29, 82.15; Mass: MS-ESI (m / z): [M + - 1] 278.93.

[0091] (5) 6-(4-fluorophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3e) (Compound 13) Pale yellow crystals, yield: 73%; MP: 190.4 ℃; UV (MeOH); λmax = 318 nm; IR: (KBr) (ν, cm -1 1642 (C=O), 1678 (C=O); 1 H-NMR(400 MHz, DMSO-D6): δ 12.80 (s, 1H, -OH), 10.56 (s, 1H, -OH), 8.59 (s, 1H, -NH), 8.12 (s, 1H, -NH), 7.99-7.97 (d, J = 7.1 Hz, 2H, ArH), 7.54-7.52 (d, J = 6.6 Hz, 2H, ArH), 7.21(s, 1H, -CH); 13 C-NMR (101 MHz, DMSO-D6) δ 170.74, 162.92, 160.04, 159.45, 144.50, 129.70, 127.00, 127.00 126.25, 126.25, 90.93, 82.13; Mass: MS-ESI (m / z): [M + - 1] 263.02.

[0092] (6) 6-(4-bromophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3f) (Compound 14) White crystals, yield: 73%; MP: 240.2 ℃; UV (MeOH): λmax = 307 nm; IR: (KBr) (ν, cm -1 1685 (C=O), 1627 (C=O); 1H-NMR(400 MHz, DMSO-D6): δ 12.66 (s, 1H, -OH), 10.41 (s, 1H, -OH), 8.40 (s, 1H, -NH), 7.83-7.81 (d, J = 8.2 Hz, 2H, ArH), 7.71-7.69 (d, J = 7.7 Hz, 2H, ArH), 7.39 (s, 1H, NH2), 7.11 (s, 1H, CH); 13 C-NMR (101 MHz, DMSO-D6): δ 170.49, 162.53, 159.10, 159.04, 132.71, 132.71, 130.28, 128.46, 128.46, 126.81, 92.10, 90.70; Mass: MS-ESI (m / z): [M + - 1] 324.

[0093] (7) 4-(hydroxyamino)-2-oxo-6-(o-tolyl)-1,2-dihydropyridine-3-carboxylic acid (3g) (Compound 4) White crystals, yield: 76%; MP: 223.4℃; UV (MeOH) λmax = 301 nm; IR: (KBr) (ν, cm -1 1664(C=O), 1621(C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 12.69 (s, 1H, OH), 10.44 (s, 1H, OH), 8.42 (s, 1H, NH), 7.46-7.31 (m, 5H, ArH & NH), 6.61 (s, 1H, CH), 2.36 (s, 3H, CH3); 13 C-NMR (101 MHz, DMSO-D6): δ 170.26, 162.97, 162.70, 159.04, 136.64, 132.25, 131.73, 131.31, 129.38, 126.85, 102.47, 95.76, 20.63; Mass: MS-ESI (m / z): [M + - 1] 258.98.

[0094] (8) 6-(2-chlorophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3h) (Compound 12) Brown crystals, yield: 73%; MP: 209.1℃; UV (MeOH): λmax = 295 nm. IR: (KBr) (ν, cm -1 1670 (C=O), 1617 (C=O). 1 H-NMR (400 MHz, DMSO-D6) δ 12.66 (s, 1H, OH), 10.44 (s, 1H, OH), 8.39 (s, 1H, NH), 7.67-7.41 (m, 5H, ArH & NH), 6.80 (s, 1H, CH); 13 C-NMR (400MHz, DMSO-d6) δ 170.49, 157.82, 148.85, 130.61, 129.22, 129.00, 128.59, 101.18, 29.44. Mass: MS-ESI (m / z): [M + - 1] 278.97.

[0095] (9) 4-(hydroxyamino)-6-(2-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3i) (Compound 8) White-yellow crystals, yield: 75%; MP: 247.3 ℃; UV (MeOH) λmax = 326 nm; IR: (KBr) (ν, cm -1 1650(C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 12.66 (s, 1H, OH), 10.40 (s, 1H, OH), 8.51 (s, 1H, NH), 7.82-7.80 (d, J = 7.7 Hz, 1H, ArH), 7.59 (m, 1H, ArH), 7.44 (s, 1H, NH), 7.38 (s, 1H, CH), 7.29 (d, J = 8.8 Hz, 1H, ArH), 7.18 (m, 1H, ArH), 3.98 (s, 3H, OCH3); 13C-NMR (101 MHz, DMSO-D6) δ 170.62, 162.86, 159.56, 158.24, 157.49, 133.36, 129.20, 121.42, 119.66, 113.14, 96.32, 82.15, 56.62; Mass: MS-ESI (m / z): [M + - 1] 275.01.

[0096] (10) 4-(hydroxyamino)-2-oxo-6-(m-tolyl)-1,2-dihydropyridine-3-carboxylic acid (3j) (Compound 3) White crystals, yield: 65%; MP: 221.8℃; UV (MeOH) λmax = 310nm. IR: (KBr) (ν, cm -1 ) 1686 (C=O); Mass: MS-ESI (m / z): [M + - 1] 259.04.

[0097] (11) 6-(3-chlorophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3k) (Compound 11) Yellowish-white crystals, yield: 72%; MP: 234.7℃; UV (MeOH) λmax = 308 nm. IR: (KBr) (ν, cm -1 1688 (C=O), 1637 (C=O); 1 H-NMR (400MHz, DMSO-d6): δ 9.09 (s, 1H, -OH), 7.67 (d, J = 4.8Hz, 1H, Ar-H), 7.64 (d, J = 2Hz, 1H, Ar-H), 7.15 (t, J = 3.6Hz, 1H, Ar-H), 6.73 (s, 1H, isoxazole), 5.59 (brs, 2H, -NH2), 3.49 (s, 2H, -CH2). 13C-NMR (101 MHz, DMSO-d6) δ170.59, 162.49, 159.03, 158.44, 134.42, 133.27, 131.84, 131.60, 126.15, 125.22, 92.87, 82.11; Mass: MS-ESI (m / z): [M + - 1] 278.95.

[0098] (12) 6-(3-bromophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3l) (Compound 15) White crystals, yield: 73%; MP: 231.4℃; UV (MeOH) λmax = 305 nm; IR: (KBr) (ν, cm -1 ) 1687 (OH), 1634 (CH2). 1 H-NMR (400 MHz, DMSO-D6) δ 12.68 (s, 1H, OH), 10.45 (s, 1H, OH), 8.39 (s, 1H, NH), 8.05 (s, 1H, NH), 7.90 (d, J = 7.7 Hz, 1H, ArH), 7.73 (d, J = 8.8 Hz, 1H, ArH), 7.49-7.44 (m, 1H, ArH), 7.40 (s, 1H, ArH), 7.17 (s, 1H, CH); 13 C-NMR (101 MHz, DMSO-D6) δ 170.47, 162.15, 159.10, 158.34, 134.91, 133.32, 131.81, 128.71, 125.58, 122.78, 93.06, 81.86; Mass: MS-ESI (m / z): [M + - 1] 324.94.

[0099] (13) 4-(hydroxyamino)-6-(4-isopropylphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3m) (Compound 9) Yellow crystals, yield: 75%; MP: 174.4℃; UV (MeOH): λmax = 311 nm; IR: (KBr) (ν, cm -1 1680 (C=O), 1640 (C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 12.62 (s, 1H, OH), 10.38 (s, 1H, OH), 8.42 (s, 1H, NH), 7.81 (d, J = 8.2 Hz, 2H, ArH), 7.39-7.34 (m, 3H, ArH& NH), 7.02 (s, 1H, CH), 2.92 (m, 1H, CH), 1.18 (d, J = 6.6 Hz, 6H, CH3); 13 C-NMR (101 MHz, DMSO-D6) δ 170.45, 162.95, 160.31, 159.31, 153.03, 128.84, 127.71, 127.71, 126.44, 126.44,90.93, 81.88, 33.91, 24.18; Mass: MS-ESI (m / z): [M + - 1] 286.98

[0100] (14) 4-(hydroxyamino)-6-(naphthalen-2-yl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3n) (Compound 16) Pale yellow crystals, yield: 76%; MP: 237.6℃; UV (MeOH) λmax = 284,320 nm; IR: (KBr) (ν,cm) -1 1682 (C=O); 1H-NMR (400 MHz, DMSO-D6) δ 12.68 (s, 1H, OH), 10.46 (s, 1H, OH), 8.51-8.45 (d, J = 23.6 Hz, 2H, NH & NH), 8.10-7.96 (m, 4H, ArH), 7.59-7.58 (m, 2H, ArH), 7.39 (s, 1H, ArH), 7.25 (s, 1H, CH); 13 C-NMR (101 MHz, DMSO-D6) δ 170.58, 162.59, 160.02, 159.18, 134.83, 133.04, 129.66, 129.41, 128.65, 128.38, 128.19, 127.65, 126.92, 122.90, 92.12, 82.04; Mass: MS-ESI (m / z): [M + - 1] 290.0.

[0101] (15) 6-(2,4-dimethylphenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3o) (Compound 5) Yellowish-white crystals, yield: 79%; MP: 229.4℃; UV (MeOH) λmax = 301 nm; IR: (KBr) (ν, cm -1 1692 (C=O), 1633 (C=O); 1 H-NMR (400 MHz, DMSO-D6) δ 12.57 (s, 1H, OH), 10.39 (s, 1H, OH), 8.41 (s, 1H, NH), 7.36 (m, 2H, ArH), 7.13-7.10 (m, 2H, ArH & NH), 6.58 (s, 1H, CH), 2.34 (s, 3H, CH3), 2.28 (s, 3H, CH3); 13C-NMR (101 MHz, DMSO-D6): δ 170.56, 163.03, 162.82, 159.24, 141.39, 136.64, 132.69, 129.41, 129.36, 127.46, 95.61, 81.71, 21.59, 20.69. Mass: MS-ESI (m / z): [M + - 1] 272.99.

[0102] (16) 6-(2-hydroxy-4-methylphenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (3p) (compound 6) White crystals, yield: 76%; MP: 209.4 ℃; UV (MeOH) λmax = 271 nm; IR: (KBr) (ν, cm -1 ) 1682 (C=O).

[0103] [Example 1-B] Synthesis of 2-pyridone-3-carboxylic acid derivatives (Synthesis of compounds represented by formula (I) where R is not a hydrogen atom)

[0104] General Information: The solvents and reagents, with the exception of tetrahydrofuran (THF), were used without any special purification. The THF was dried using sodium. The progress of the reaction was confirmed by TLC on a pre-coated silica gel plate (Kieselgel 60 F254, Merck), and spots were detected under UV light (254 nm). Purification was performed by column chromatography using silica gel (particle size 100-200 mesh, Fisher Scientific). １ H and １３ The 13C-NMR spectrum was measured in DMSO-d6 using a JEOL 400MHz instrument. Chemical shifts were recorded in ppm(δ) using tetramethylsilane (TMS) as an internal standard. The mass spectrum was measured in HPLC-grade methanol using an Orbitrap Exploris 120 (HRMS). The IR spectrum was measured with a BRUKER (FTIR) spectrometer. The UV spectrum was measured with a LAB INDIA UV-Vis spectrophotometer. The melting point was measured with a STUART automated melting point analyzer and no correction was applied.

[0105]

[0106] The following compounds 17-25 (4a-i) were synthesized.

[0107]

[0108] Synthesis of 3,3-bis(methylthio)-1-(4-methylphenyl)propa-2-en-1-one (1a) p-methylacetophenone was added dropwise to a THF solution of NaH under stirring at 0°C. After stirring the suspension for 10 minutes, CS ２ The reaction mixture was added dropwise. After stirring the reaction mixture for 10 minutes, MeI was added dropwise. The reaction mixture was slowly allowed to return to room temperature, and stirring was continued for 12 hours while monitoring the reaction by TLC. The reaction mixture was poured into ice water and then filtered. The crude product was purified by recrystallization with ethyl acetate and n-hexane to obtain 1a.

[0109] Synthesis of 4-(methylthio)-6-(4-methylphenyl)-2-oxo-2H-pyran-3-carboxylic acid (2a) DMM was added dropwise to a dioxane solution in NaH under stirring at 0°C and stirred for 30 minutes. 1a was added, and the reaction mixture was allowed to return to room temperature and stirred for another 10 minutes. The reaction mixture was then heated at 80°C for 8 hours while monitoring the progress of the reaction by TLC. The reaction mixture was poured into ice water and washed with ethyl acetate to remove organic impurities. The aqueous layer was neutralized with 1.5N HCl and then filtered using a vacuum pump to obtain 2a.

[0110] Synthesis of N-phenyl-4-(methylthio)-6-(4-methylphenyl)-2-oxo-2H-pyran-3-carboxamide (3a) To a DMF solution of 2a under stirring at room temperature, 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate (HATU) and N,N-diisopropylethylamine were added. After 10 minutes, the amine compound was added and the mixture was stirred at room temperature for a further 4 hours. The progress of the reaction was confirmed by TLC, and then the mixture was poured into ice water while stirring. The precipitate was filtered and recrystallized in a mixed solvent of ethyl acetate and n-hexane to obtain 3a.

[0111] Synthesis of 4-(hydroxyamino)-6-(4-methylphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3-carboxylic acid (4a) N-methylpiperazine and K2CO3 were added to an ethanol solution of 3a. After 20 minutes, hydroxylamine hydrochloride was added and the mixture was stirred for a further 12 hours under reflux at 80°C. Completion of the reaction was confirmed by TLC. The solvent was removed under reduced pressure, ice water was added, and the resulting precipitate was filtered. The crude product was purified by column chromatography using a suitable solvent mixture to obtain 4a.

[0112] As described above, the 2-pyridone-3-carboxylic acid derivative 4a (compound 17 of the present invention) was synthesized.

[0113] In the same manner as described above, 2-pyridone-3-carboxylic acid derivatives 4b-i (compounds 18-25 of the present invention) were synthesized.

[0114] The physical properties of the obtained 2-pyridone-3-carboxylic acid derivatives 4a-i (compounds 17-25 of the present invention) are shown below.

[0115] (17) 4-(hydroxyamino)-6-(4-methylphenyl)-2-oxo-1-phenyl-1,2-dihydropyridine-3-carboxylic acid (4a) (Compound 17) Light yellow powder: Yield 75%; mp: 219-223℃; IR(KBr):3233(OH), 2924(NH), 1660(C=O); UV(MeOH) λmax= 286 nm; 1 H NMR: (400MHz, DMSO-d6):δ 2.364(s,3H, CH3),7.043(s, 1H ,Pyridone), 7.832(d,Ar H), 7.570(d,Ar H), 7.365(m, Ar H), 7.137(m, Ar H), 12.446(s, OH), 11.329(s, NH), 10.557(s,OH); HRMS calculated for ([C 19 H 16 N2O4] - H): 335.1032 found ([C 19 H 16 N2O4] - H) -: 335.1026.

[0116] (18) 6-(2-fluorophenyl)-4-(hydroxyamino)-2-oxo-1-phenyl-1,2-dihydropyridine-3-carboxylic acid (4b) (Compound 18) Yellow powder: 80% yield; mp: 228-230℃; IR (KBr): 3346(OH), 2927(NH), 1644(C=O); UV (MeOH) λmax = 280 nm; 1 H NMR: (400MHz, DMSO-d6): δ 2.473(s 2.473,3H, CH3), 7.177(s, 1H,Pyridone), 8.0022-8.008(d, Ar H), 7.999-7.986(d Ar H), 7.593-7.380(m, Ar H),12.421(s,OH), 11.305(s,NH), 10.595(s,OH); HRMS calculated for ([C 18 H 13 FN2O4] - H):339.0781 found ([C 18 H 13 [FN2O4] - H) - : 339.0776.

[0117] (19) 1-(4-fluorophenyl)-4-(hydroxyamino)-6-(2-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (4c) (Compound 19) Yellow powder: yield 65%; mp: 210-212℃; IR (KBr): 3345 (OH), 2847 (NH), 1640 (C=O); UV (MeOH) λmax = 306 nm; 1H NMR: (400MHz, DMSO-d6): δ 2.473(s 2.473,3H, CH3), 7.379(s, 1H,Pyridone), 7.7999-7.777(d, Ar H), 7.621-7.587(d Ar H), 7.242-7.174(m, Ar H),12.304(s,OH), 11.314(s,NH), 10.518(s,OH); HRMS calculated for ([C 19 H 15 FN2O5] - H):369.0887 found ([C 19 H 15 [FN2O5] - H) - : 369.0881.

[0118] (20) 1-(4-bromophenyl)-6-(4-chlorophenyl)-4-(hydroxyamino)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (4d) (Compound 20) Yellow powder: yield 68%; mp: 212-215℃; IR (KBr): 3249(OH), 2924(NH), 1660(C=O); UV (MeOH) λmax = 301 nm; HRMS calculated for ([C 18 H 12 BrClN2O4] - H):432.9591 found ([C 18 H 12 [BrClN2O4] - H) - : 432.9585.

[0119] (21) 4-(hydroxyamino)-2-oxo-1,6-diphenyl-1,2-dihydropyridine-3-carboxylic acid (4e) (Compound 21) Yellow powder: yield 55%; mp: 217-220℃; IR (KBr): 3272 (OH), 2923 (NH), 1661 (C=O); UV (MeOH) λmax = 301 nm; HRMS calculated for ([C 18 H 14 [N2O4] - H):369.0887 found ([C 18H 14 [N2O4]- H) - : 321.0870.

[0120] (22) 6-(furan-2-yl)-4-(hydroxyamino)-1-(2-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (4f) (Compound 22) Bright yellow powder: yield 55%; mp: 192-198℃; IR (KBr): 3190 (OH), 2920 (NH), 1665 (C=O); UV (MeOH) λmax = 334 nm; ([C 17 H 14 N2O6] - H): 341.0774 found ([C 17 H 14 [N2O6] - H) - : 341.0768.

[0121] (23) 1-(3-fluorophenyl)-4-(hydroxyamino)-6-(4-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3-carboxylic acid (4g) (Compound 23) Yellow powder: yield 55%; mp: 194-196℃; IR (KBr): 3199(OH), 2925(NH), 1679(C=O); UV (MeOH) λmax = 344 nm; ([C 19 H 15 N2O5] - H): 369.0887 found ([C 19 H 15 [N2O5] - H) - : 369.0866.

[0122] (24) 4-(hydroxyamino)-1-isopropyl-2-oxo-6-phenyl-1,2-dihydropyridine-3-carboxylic acid (4h) (Compound 24) Yellow powder: yield 55%; mp: 210-215℃; IR (KBr): 3206(OH), 2924(NH), 1668(C=O); UV (MeOH) λmax = 309 nm; ([C 15 H 16N2O4] - H): 287.1032 found ([C 15 H 16 N2O4] - H) - : 287.1032.

[0123] (25) 4-(hydroxyamino)-1-(2-methoxyphenyl)-2-oxo-6-(naphthalen-2-yl)-1,2-dihydropyridine-3-carboxylic acid (4i) (Compound 25) Yellow powder: Yield 55%; mp:228-230℃; IR(KBr):3187(OH), 2967(NH), 1650(C=O); UV(MeOH) λmax= 334 nm; ([C 23 H 18 N2O5] - H): 401.1137 found ([C 23 H 18 N2O5] - H) - : 401.1132.

[0124] [Example 2] Anti-SARS-CoV-2 effect in VeroE6 / TMPRSS2 cells A schematic of the anti-SARS-CoV-2 assay is shown in Figure 1.

[0125] VeroE6 / TMPRSS2 cells, which are highly susceptible to SARS-CoV-2, were seeded in 96-well microplates (2 × 10⁻¹⁰). ４ Cells / well). After culturing at 37°C for 24 hours, cells were infected with SARS-CoV-2 standard strain WK-521 at a multiplicity of infection (MOI) of 0.002, or with Omicron BA. 5 mutant strain TY41-702 at an MOI of 0.01, and cultured at 37°C for 72 hours in the presence of various concentrations of the test compound. After culturing, the number of viable cells was measured by the MTT method. All experiments were repeated at least twice using 3 wells for each concentration. The anti-SARS-CoV-2 effect and cytotoxicity of the test compound were determined by comparing the number of viable cells in infected and uninfected cells with those without the test compound.

[0126] Table 1 shows the anti-SARS-CoV-2 effect of the test compound. In this table, EC ５０The value corresponds to CC ５０ When the value is smaller than this, it can be determined that this compound has a selective anti-SARS-CoV-2 effect. Also, CC ５０ The value of EC ５０ The value obtained by dividing by the given value is called the selectivity coefficient (SI), and the larger this value, the more selective the effect of inhibiting viral replication is considered to be.

[0127]

[0128] [Example 3] Anti-SARS-CoV-2 effect in HeLa-ACE2 cells HeLa-ACE2 cells were seeded in a 96-well microplate (1 × 10⁻¹⁶). ４ Cells / well). After culturing at 37°C for 24 hours, the cells were infected with the SARS-CoV-2 standard strain WK-521 at MOI = 0.1 and cultured at 37°C for 72 hours in the presence of various concentrations of the test compound. After culturing, PrimeDirect ＴＭ Using Probe RT-qPCR Mix (Takara Bio Inc.) according to the instructions, viral RNA levels in the culture supernatant were measured using the MTT method and real-time RT-PCR method. All experiments were performed using three wells for each concentration.

[0129] The results for compound 5 and nilmatrelvir of the present invention are shown in Figure 2. In Figure 2, EC ５０ This indicates a 50% effective concentration based on inhibition of viral RNA levels in the culture supernatant of infected cells. In this experiment, compound 5 showed anti-SARS-CoV-2 activity at very low concentrations, similar to nilmatrelvir.

[0130] [Example 4] Investigation of mechanism of action (target molecule) (1) Effect of SARS-CoV-2 on RNA-dependent RNA polymerase This assay was performed using the SARS-CoV-2 RNA polymerase assay kit from ProFoldin (Hudson, Massachusetts) according to its instructions. All experiments were performed using 3 wells for each concentration. The results are shown in Figure 3. In Figure 3, "PC" indicates "enzyme present, compound absent," and "NC" indicates "neither enzyme nor compound present." The compound of the present invention did not inhibit the activity of SARS-CoV-2 RNA-dependent RNA polymerase.

[0131] (2) Effect of SARS-CoV-2 on 3CL protease This assay was performed using the SARS-CoV-2 3CL protease assay kit from BPS Bioscience (San Diego, California) according to its instructions. All experiments were performed using three wells for each concentration.

[0132] The results are shown in Figure 4. In Figure 4, "PC" indicates "enzyme present, no compound", "NC" indicates "neither enzyme nor compound present", "1-1" indicates compound 5 (100 μM), "1-2" indicates compound 5 (10 μM), "2-1" indicates compound 6 (100 μM), "2-2" indicates compound 6 (10 μM), and "3" indicates nilmatrellvir (10 μM).

[0133] The compounds of the present invention did not inhibit the activity of SARS-CoV-2 3CL protease.

[0134] Existing anti-SARS-CoV-2 drugs, remdesivir and mornupiravir, inhibit the viral RNA-dependent RNA polymerase, while nilmatrelvir and encitrelvir inhibit the main protease necessary for viral replication (3CL protease in the case of coronavirus). On the other hand, in the investigation of the mechanism of action (target molecule) described above, the compound of the present invention did not inhibit the activity of either SARS-CoV-2 RNA-dependent RNA polymerase or 3CL protease. Therefore, it was thought that the target molecule of the compound of the present invention is an inhibitor with a different mechanism of action from existing anti-SARS-CoV-2 drugs.

[0135] According to the present invention, an antiviral agent effective against SARS-CoV-2 can be provided.

[0136] This application is based on Japanese Patent Application No. 2024-232249, filed in Japan on December 27, 2024, the contents of which are fully incorporated herein.

Claims

1. The following formula (I): Compounds represented by (wherein Ar is a substituted or unsubstituted aromatic group, and R is a hydrogen atom, a substituted or unsubstituted aromatic group, or a substituted or unsubstituted alkyl group), salts thereof, solvates thereof, or prodrugs thereof.

2. In formula (I) above, Ar is either substituted or unsubstituted C. １－６ - Alkyl, substituted or unsubstituted C １－６ -C13 is substituted with at least one substituent selected from an alkoxy group, a halogen atom, and a hydroxyl group, or is unsubstituted. ６－１０ - The compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof, wherein the compound is an aromatic hydrocarbon group or a five- or six-membered aromatic heterocyclic group.

3. In the above formula (I), Ar is C １－６ - Alkyl alkyl group, C １－６ - A C molecule substituted with one or two substituents selected from alkoxy groups, halogen atoms, and hydroxyl groups, or unsubstituted. ６－１０ - The compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof, wherein the compound is an aromatic hydrocarbon group or a five- or six-membered aromatic heterocyclic group.

4. In the formula (I), Ar is C １－６ -alkyl group, C １－６ -alkoxy group, and at least one substituent selected from a halogen atom, or unsubstituted, C ６－１０ -aromatic hydrocarbon group, the compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof.

5. In formula (I) above, R is a hydrogen atom; substituted or unsubstituted C １－６ - A C atom substituted with at least one substituent selected from an alkoxy group and a halogen atom, or unsubstituted. ６－１０ - Aromatic hydrocarbon group; or C １－６ - The compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof, which is an alkyl group.

6. In formula (I) above, R is a hydrogen atom; C １－６ - A phenyl group substituted with one or two substituents selected from alkoxy groups and halogen atoms, or unsubstituted; or C １－６ - The compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof, which is an alkyl group.

7. In formula (I), R is a hydrogen atom; a phenyl group substituted with one or two substituents selected from halogen atoms; or C １－６ - The compound according to claim 1, a salt thereof, a solvate thereof, or a prodrug thereof, which is an alkyl group.

8. A pharmaceutical composition comprising a compound according to any one of claims 1 to 7, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, and a pharmaceutically acceptable carrier.

9. An anti-SARS-CoV-2 agent comprising a compound according to any one of claims 1 to 7, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof.

10. The anti-SARS-CoV-2 agent according to claim 9, which does not inhibit at least one of SARS-CoV-2 RNA-dependent RNA polymerase and 3CL protease.

11. A compound according to any one of claims 1 to 7, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof, for use in the treatment or prevention of SARS-CoV-2.

12. A method for the prevention or treatment of SARS-CoV-2, comprising administering to a mammal a therapeutically effective amount of a compound according to any one of claims 1 to 7, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof.

13. Use of a compound according to any one of claims 1 to 7, a pharmaceutically acceptable salt thereof, a solvate thereof, or a prodrug thereof for the manufacture of an anti-SARS-CoV-2 drug.

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