Linazolamide derivatives and uses thereof

Abstract

The application discloses a kind of containing linezolid derivative and its application, belong to the field of pharmaceutical chemistry and antibacterial drug technology.In order to develop efficient drug against drug-resistant gram-positive bacteria, the application is based on pharmacophore fusion strategy, linezolid is modified and optimized, through molecular docking simulation, in vitro antibacterial activity screening and mechanism research, adjust compound structure, design and synthesize a series of novel structure linezolid derivatives, thus obtained antibacterial activity strong, safety good, can overcome the new antibacterial drug of drug resistance.The linezolid derivative of the application has strong inhibitory effect on gram-positive bacteria, especially on drug-resistant gram-positive bacteria (such as methicillin-resistant staphylococcus aureus), and shows excellent antibacterial effect, which can be used for treating diseases caused by gram-positive bacterial infection.

Description

Technical Field

[0001] This invention relates to the fields of pharmaceutical chemistry and antibacterial drug technology, and in particular to a linezolid derivative and its application. Background Technology

[0002] Bacterial infections have long been a major public health problem threatening human health. Since the discovery and clinical application of penicillin, the development and use of antibiotics have provided an effective means of treating bacterial infections. However, with the widespread use of antibiotics, the problem of bacterial resistance has become increasingly prominent, with multidrug-resistant bacteria (MDR), multidrug-resistant bacteria (XDR), and even pan-drug-resistant bacteria (PDR) constantly emerging, leading to the gradual ineffectiveness of many traditional antibiotics. Among them, the spread of "superbugs" such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) has become one of the most pressing threats in the global public health field.

[0003] The oxazolidinone antibiotic linezolid is a key drug for treating infections caused by drug-resistant Gram-positive bacteria and plays an important role in clinical practice. Its mechanism of action is unique; it binds to the peptidyl transferase center of the bacterial ribosomal 50S subunit, inhibiting the initiation of protein synthesis. Therefore, it exhibits no cross-resistance with other classes of antibiotics and demonstrates good antibacterial activity against resistant bacteria such as MRSA and VRE.

[0004] However, linezolid still has significant limitations in clinical application: long-term use can easily lead to bone marrow suppression, mainly manifested as thrombocytopenia and anemia; it has certain toxicity, and its inhibitory effect on monoamine oxidase may trigger drug interactions; with its increasingly widespread clinical application, bacterial resistance to linezolid is gradually emerging, and known resistance mechanisms include target mutations on 23S rRNA and the spread of acquired resistance genes (such as cfr). Furthermore, currently used linezolid has poor inhibitory effects on Gram-negative bacteria, and its antibacterial spectrum is somewhat limited.

[0005] Although some oxazolidinone derivatives are currently under investigation (such as torezolid), they generally suffer from insufficient antibacterial activity, high toxicity, and insignificant improvement effects against drug-resistant bacteria. Therefore, developing novel linezolid derivatives with novel structures, stronger antibacterial activity, lower toxicity, and the ability to effectively overcome existing drug resistance is of great significance for solving the treatment challenges of drug-resistant bacterial infections in clinical practice.

[0006] Summary of the Invention The purpose of this invention is to provide a linezolid derivative and its application to solve the above-mentioned problems in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is to provide a linezolid derivative, whose general structural formula I is: ; Where R1 is or ; R2 is , , , , , , , , , , , , , , and Any one of them.

[0008] Preferably, the linezolid-containing derivative is one of the following compounds: (S)-N-(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinylphenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl]-1H-1,2,4-triazol-3-carboxamide; 1-(4-((((S)-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(1-(1-(methanesulfonyl)pyrrolidine-3-yl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(((1-methyl-1H-pyrazol-3-yl)methyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(2-(thiophen-2-yl)ethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(4-(trifluoromethyl)cyclohexyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(1-Cyclopropylpiperidin-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(1-(1-(methanesulfonyl)piperidin-4-yl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(pyrimidin-2-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(pyridin-4-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(2-(pyridin-3-yl)ethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(3,5-difluorobenzyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(thiophen-3-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; 1-(4-((((S)-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(1-(1-(methylsulfonyl)pyrrolidine-3-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-N-(2-Cyclohexylethyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-N-(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(((1-methyl-1H-pyrazol-4-yl)methyl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(2-(thiophen-2-yl)ethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(1-(1-(methylsulfonyl)piperidin-4-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyrimidin-2-ylmethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyridin-4-ylmethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(thiophen-3-ylmethyl)-1,6-dihydropyridazine-3-carboxamide.

[0009] The second technical solution of the present invention: provides a method for preparing the above-mentioned linezolid-containing derivative, wherein R1 is... At that time, the linezolid-containing derivative was prepared according to route 1; R1 is At the same time, the linezolid-containing derivative was prepared according to route 2; Route 1 includes the following steps: mixing 4-aminobenzoic acid with sodium nitrite in a solvent to carry out a diazotization reaction to obtain a diazonium salt; The diazonium salt was subjected to a cyclization and substitution reaction with an isocyanoacetate compound and sodium acetate to obtain intermediate X2. The intermediate X2 was dissolved in an organic solvent and subjected to an amide condensation reaction with (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one in the presence of a condensing agent and a base to obtain intermediate X3. The intermediate X3 was hydrolyzed under alkaline conditions and then acidified to obtain intermediate X4. The intermediate X4 was dissolved in an organic solvent and then reacted with an amine compound in the presence of a condensing agent and a base to complete the preparation. In Route 1, the types of amine compounds are 4-aminothiophene-2-onitrile, 1-(methanesulfonyl)pyrrolidine-3-amine, 1,1-dioxotetrahydro-2H-thiopyran-4-amine, (1-methyl-1H-pyrazol-3-yl)methylamine, 2-(thiophene-2-yl)ethylamine, 4-(trifluoromethyl)cyclohexylamine, 5-cyclopropyl-1H-pyrazol-3-amine, 1-cyclopropylpiperidine-4-amine, 1-(methanesulfonyl)piperidine-4-amine, pyrimidin-2-ylmethylamine, pyridin-4-ylmethylamine, 2-(pyridin-3-yl)ethylamine, 3,5-difluorobenzylamine, or thiophene-3-ylmethylamine; The reaction formula for Route 1 is as follows: Route 1: Preparation of linezolid derivatives containing a triazole ring: ; Route 2 includes the following steps: mixing 4-aminobenzoic acid with sodium nitrite in a solvent to carry out a diazotization reaction to obtain a diazonium salt; The diazonium salt was coupled with ethyl acetoacetate and ammonium acetate to obtain intermediate Y2; The intermediate Y2 was dissolved in an organic solvent and, in the presence of a condensing agent and a base, was subjected to an amide condensation reaction with (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one to obtain intermediate Y3. The intermediate Y3 was reacted with ethyl (triphenylphosphine) in an organic solvent by a Wittig reaction to obtain intermediate Y4; The intermediate Y4 was hydrolyzed under alkaline conditions and then acidified to obtain the key intermediate Y5. The intermediate Y5 was dissolved in an organic solvent and then reacted with an amine compound in the presence of a condensing agent and a base to complete the preparation. In Route 2, the types of amine compounds are 4-aminothiophene-2-onitrile, 1-(methanesulfonyl)pyrrolidine-3-amine, 2-cyclohexylethylamine, 1,1-dioxotetrahydro-2H-thiopyran-4-amine, (1-methyl-1H-pyrazol-4-yl)methylamine, 2-(thiophene-2-yl)ethylamine, 4-(trifluoromethyl)cyclohexylamine, 5-cyclopropyl-1H-pyrazol-3-amine, 1-(methanesulfonyl)piperidin-4-amine, pyrimidin-2-ylmethylamine, pyridin-4-ylmethylamine, or thiophene-3-ylmethylamine; The reaction formula for Route 2 is as follows: Route 2: Preparation of linezolid derivatives containing pyridazinone rings: .

[0010] Preferably, the isocyanate compound is ethyl acetoacetate.

[0011] Preferably, the condensing agent is N,N,N',N'-tetramethylchloroformamidin hexafluorophosphate, and the base is N-methylimidazole.

[0012] The third technical solution of the present invention provides a pharmaceutical composition in which the active ingredient includes the above-mentioned linezolid derivative.

[0013] Preferably, the pharmaceutical composition further contains pharmaceutically acceptable excipients.

[0014] Preferably, the pharmaceutically acceptable excipient refers to any diluent, adjuvant, and / or carrier that can be used in the pharmaceutical field. The derivatives of this invention can be used in combination with other active ingredients, provided they do not produce other adverse effects, such as allergic reactions.

[0015] Preferably, the clinical dosage of the linezolid derivative for patients can be adjusted based on the therapeutic efficacy and bioavailability of the active ingredient in vivo, its metabolic and excretion rates, and the patient's age, sex, and disease severity. The daily dose for adults should generally be 10–500 mg, preferably 50–300 mg. The linezolid derivative can be administered in divided doses at regular intervals (preferably one to six times) as directed by a physician or pharmacist.

[0016] Preferably, the dosage form of the pharmaceutical composition is a tablet, capsule, ointment, aerosol, suppository, drop pill, topical liniment, injection, or film.

[0017] Preferably, the carrier is a common type available in the pharmaceutical field, including at least one of binders, lubricants, disintegrants, solubilizers, diluents, stabilizers, suspending agents, pigments, flavoring agents, preservatives, solvents, and matrices.

[0018] Pharmaceutical formulations can be administered orally or via parenteral route (e.g., intravenously, subcutaneously, intraperitoneally, or locally). If certain drugs are unstable under gastric conditions, they can be formulated into enteric-coated tablets.

[0019] The fourth technical solution of the present invention provides the use of the above-mentioned linezolid derivative or the above-mentioned pharmaceutical composition in the preparation of a medicament for treating and / or preventing bacterial infectious diseases.

[0020] Preferably, the bacterial species causing the bacterial infectious disease are at least one of Staphylococcus aureus and Staphylococcus epidermidis.

[0021] The pharmaceutical composition of the present invention is suitable for treating diseases such as skin and soft tissue infections, pneumonia, bloodstream infections, and abdominal infections caused by the above-mentioned bacteria.

[0022] The beneficial technical effects of the present invention are as follows: In order to develop highly effective drugs against drug-resistant Gram-positive bacteria, this invention modifies and optimizes the structure of linezolid based on a pharmacophore fusion strategy. Through molecular docking simulation, in vitro antibacterial activity screening and mechanism of action studies, the compound structure is adjusted, and a series of novel linezolid derivatives are designed and synthesized, thereby obtaining a new type of antibacterial drug with strong antibacterial activity, good safety and the ability to overcome drug resistance.

[0023] The linezolid derivative of the present invention has a strong inhibitory effect on Gram-positive bacteria, especially showing excellent antibacterial effect against drug-resistant Gram-positive bacteria (such as methicillin-resistant Staphylococcus aureus), and can be used to treat diseases caused by Gram-positive bacterial infections. Attached Figure Description

[0024] Figure 1The results are the hemolytic safety evaluation results for Example 19.

[0025] Figure 2 The results are from the in vivo toxicity experiment in KM mice in Example 19.

[0026] Figure 3 The results of HE staining of internal organs in KM mice in Example 19 are shown.

[0027] Figure 4 This is a time-killing kinetic curve of Staphylococcus aureus in Example 19.

[0028] Figure 5 This is a time-based bactericidal kinetic diagram of Staphylococcus aureus in Example 19.

[0029] Figure 6 This is a time-based bactericidal kinetic curve of methicillin-resistant Staphylococcus aureus in Example 19.

[0030] Figure 7 This is a time-based bactericidal kinetic diagram of methicillin-resistant Staphylococcus aureus in Example 19.

[0031] Figure 8 This is an electrophoresis diagram of the effect of Example 19 on MRSA nucleic acid leakage.

[0032] Figure 9 The images show a comparison of SEM images after treatment with Staphylococcus aureus in Example 19. In the images, A represents the control group, B represents the 1×MIC group, C represents the 2×MIC group, and D represents the 4×MIC group.

[0033] Figure 10 The images shown are SEM images after MRSA processing in Example 19. In the images, A represents the blank group, B represents the 1×MIC group, C represents the 2×MIC group, and D represents the 4×MIC group.

[0034] Figure 11 This is a statistical analysis of the treatment effects of the KM mouse infection model in Example 19.

[0035] Figure 12 HE staining results of in vivo organs from the KM mouse infection model in Example 19. Figure 13 This is a morphological observation of liver tissue in mice after treatment with bacterial infection, as described in Example 19. Figure 14 The effect of Example 19 on the expression of IL-1, IL-6, and TNF-α in the liver of mice infected with bacteria. Figure 15 The immunohistochemical results for the expression of IL-1, IL-6, and TNF-α in the liver of bacterial-infected mice are shown in Example 19. Figure 16This is a morphological observation of liver tissue in mice after treatment with bacterial infection, as described in Example 19. Figure 17 The effect of Example 19 on the expression of IL-1, IL-6, and TNF-α in the kidneys of mice infected with bacteria. Figure 18 The immunohistochemical results for the expression of IL-1, IL-6, and TNF-α in the kidneys of bacterial-infected mice are shown in Example 19. Detailed Implementation

[0036] The proton NMR spectra of the compounds of this invention were determined using a Bruker ARX-400, and the mass spectra were determined using an Agilent 1100 LC / MSD; all reagents used were of analytical or chemical purity.

[0037] The raw materials used in this invention are prepared by methods well known to those skilled in the art of organic chemistry, or are commercially available, as described in the synthetic routes. All linezolid derivatives of this invention are prepared by methods well known to those skilled in the art of organic chemistry, as described in the synthetic routes. All variable factors used in the synthetic routes are as defined below or as defined in the claims.

[0038] The technical solution of the present invention will be further illustrated by the following embodiments.

[0039] The structural formulas of embodiments 1-25 of the present invention are shown in Table 1 below.

[0040] Table 1: Structural Formulas of Examples 1-25 Example 1: ( S )- N Preparation of -(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinylphenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl]-1H-1,2,4-triazol-3-carboxamide The preparation was carried out according to the synthetic route of linezolid containing a triazole ring, as described in Route 1: 4-aminobenzoic acid (3.0 g, 21.9 mmol) was used as the starting material and dissolved in 10 ml of 10% HCl solution in an ice bath at 0–5 °C. Sodium nitrite (1.8 g, 26.1 mmol) was added and stirred for 0.5–1 hour to complete diazotization, yielding a diazonium salt. The obtained diazonium salt did not need to be separated and was directly added to ethyl isocyanate (2.47 g, 21.9 mmol) and sodium acetate (trihydrate, 10.8 g, approximately 79.4 mmol) for cyclization and substitution reactions to construct the 1,2,4-triazole ring intermediate X2. X2 was dissolved in 20 mL of acetonitrile, and TCFH (N,N,N',N'-tetramethylchloromethanemidane hexafluorophosphate, 6.14 g, 21.9 mmol) and NMI (N-methylimidazolium, 2.16 g, 26.3 mmol) were added. The mixture was stirred at room temperature (23 °C) until TLC showed complete activation of the carboxyl group. Then, (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one (7.42 g, 24.1 mmol) was added to form an amide bond, yielding intermediate X3. X3 was dissolved in 30 mL of a methanol and water mixture (1:10 v / v), and lithium hydroxide monohydrate (1.01 g, 24.1 mmol) was added. The mixture was stirred at 60 °C until the ester bond was completely hydrolyzed, and then acidified with dilute hydrochloric acid to pH ≈ 3 to obtain the key intermediate X4. Finally, X4 was dissolved again in 10 ml of acetonitrile, and TCFH (6.14 g, 21.9 mmol) and NMI (2.16 g, 26.3 mmol) were added to activate the carboxyl group. Then, it was reacted with 4-aminothiophene-2-onitrile at room temperature to form a new amide bond. The final target compound was obtained by column chromatography purification. The yield of the final product was 70%, and the purity was 93%.

[0041] Route 1: Preparation of linezolid derivatives containing a triazole ring: .

[0042] Structural confirmation: ESI-MS / (m / z): 673.2654(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 11.44 (s, 1H), 9.65 (s, 1H), 9.03 (s,2H), 8.28 (s, 1H), 8.16 (s, 1H), 8.09 (s, 3H), 7.68 (d, J = 12.7 Hz, 1H),7.55 – 7.45 (m, 1H), 7.20 (d, J = 9.0 Hz, 1H), 7.07 (t, J = 9.4 Hz, 1H), 4.88(s, 1H), 4.18 (t, J = 8.8 Hz, 1H), 3.86 (s, 1H), 3.73 (d, J = 5.6 Hz, 4H),3.66 (s, 2H), 2.96 (s, 4H) Example 2: 1-(4-(((() S )-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of -(1-(methanesulfonyl)pyrrolidine-3-yl)-1H-1,2,4-triazole-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with an equimolar amount of 1-(methanesulfonyl)pyrrolidine-3-amine, and the rest of the operation is the same.

[0043] Structural confirmation: ESI-MS / (m / z): 714.2387(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.56 (s, 1H), 9.03 (d, J = 4.8 Hz, 1H), 8.11 – 8.00 (m, 3H), 7.48 (d, J = 15.3 Hz, 1H), 7.19 (d, J = 8.8 Hz, 1H),7.05 (t, J = 9.4 Hz, 1H), 4.86 (s, 1H), 4.16 (t, J = 9.1 Hz, 1H), 3.91 (s,3H), 3.77 – 3.57 (m, 6H), 3.16 (d, J = 5.1 Hz, 1H), 3.01 (s, 1H), 2.94 (s, 4H), 2.68 (s, 1H), 1.23 (s, 1H), 0.84 (d, J = 7.6 Hz, 1H) Example 3: ( S)- N Preparation of -(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1,1-dioxotetrahydro-2H-thiopyran-4-amine, and the rest of the operation is the same.

[0044] Structural confirmation: ESI-MS / (m / z): 727.2498(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.63 – 9.47 (m, 1H), 9.00 (d, J = 5.8 Hz,1H), 8.83 (d, J = 8.4 Hz, 1H), 8.15 – 7.98 (m, 4H), 7.49 (d, J = 15.0 Hz,1H), 7.20 (d, J = 8.8 Hz, 1H), 7.06 (t, J = 9.2 Hz, 1H), 4.95 – 4.83 (m, 1H), 4.17 (t, J = 9.0 Hz, 1H), 3.91 – 3.83 (m, 1H), 3.77 – 3.71 (m, 4H), 3.67 (d,J = 8.3 Hz, 2H), 3.10 (d, J = 8.7 Hz, 3H), 2.96 (q, J = 5.4, 4.4 Hz, 5H), 2.27 – 2.06 (m, 2H), 1.18 (t, J = 7.2 Hz, 4H) Example 4: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of -((1-methyl-1H-pyrazole-3-yl)methyl)-1H-1,2,4-triazole-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with (1-methyl-1H-pyrazol-3-yl)methylamine, and the rest of the operation is the same.

[0045] Structural confirmation: ESI-MS / (m / z): 647.2418(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.49 (d, J = 1.7 Hz, 1H), 9.07 – 8.94 (m,1H), 8.63 (t, J = 5.7 Hz, 1H), 8.16 – 7.93 (m, 4H), 7.60 (s, 1H), 7.36 (s,1H), 6.82 (t, J = 9.2 Hz, 1H), 6.52 – 6.30 (m, 2H), 5.55 (d, J = 6.1 Hz, 1H), 5.10 (d, J = 5.0 Hz, 1H), 4.29 (d, J = 6.0 Hz, 2H), 3.90 – 3.63 (m, 8H), 3.17– 3.01 (m, 1H), 2.94 (dt, J = 12.6, 6.1 Hz, 2H), 2.87 – 2.72 (m, 4H) Example 5: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N- Preparation of (2-(thiophen-2-yl)ethyl)-1H-1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 2-(thiophene-2-yl)ethylamine, and the rest of the operation is the same.

[0046] Structural confirmation: ESI-MS / (m / z): 658.2341(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.49 (d, J = 1.7 Hz, 1H), 9.07 – 8.94 (m,1H), 8.63 (t, J = 5.7 Hz, 1H), 8.16 – 7.93 (m, 4H), 7.60 (s, 1H), 7.36 (s,1H), 6.82 (t, J = 9.2 Hz, 1H), 6.52 – 6.30 (m, 2H), 5.55 (d, J = 6.1 Hz, 1H), 5.10 (d, J = 5.0 Hz, 1H), 4.29 (d, J = 6.0 Hz, 2H), 3.90 – 3.63 (m, 8H), 3.17– 3.01 (m, 1H), 2.94 (dt, J = 12.6, 6.1 Hz, 2H), 2.87 – 2.72 (m, 4H) Example 6: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of 3-(4-(trifluoromethyl)cyclohexyl)-1H-1,2,4-triazole-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 4-(trifluoromethyl)cyclohexylamine, and the rest of the operation is the same.

[0047] Structural confirmation: ESI-MS / (m / z): 753.2893(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.52 (s, 1H), 9.01 (dd, J = 6.9 Hz, 1H), 8.05 (s, 4H), 7.49 (d, J = 14.9 Hz, 1H), 7.19 (d, J = 8.9 Hz, 1H), 7.06 (t, J= 9.4 Hz, 1H), 4.87 (s, 1H), 4.16 (t, J = 8.8 Hz, 1H), 3.85 (s, 1H), 3.69 (d,J = 30.3, 6 Hz, 1H), 2.92 (d, J = 21.0, Hz, 6H), 1.90 (s, 3H), 1.68 (s, 4H),1.39 (d, J = 12.5 Hz, 1H) Example 7: ( S )- N Preparation of -(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 5-cyclopropyl-1H-pyrazole-3-amine, and the rest of the operation is the same.

[0048] Structural confirmation: ESI-MS / (m / z): 657.2521(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 12.28 (s, 1H), 10.38 (s, 1H), 9.55 (s,1H), 9.01 (t, J = 5.9 Hz, 1H), 8.08 (s, 4H), 7.49 (dd, J = 15.0, 2.8 Hz, 1H),7.28 – 6.95 (m, 2H), 6.43 – 6.19 (m, 1H), 4.88 (p, J = 6.3 Hz, 1H), 4.17 (t,J = 9.0 Hz, 1H), 3.96 – 3.57 (m, 7H), 3.06 – 2.85 (m, 4H), 1.91 (t, J = 6.4Hz, 1H), 1.06 – 0.61 (m, 4H) Example 8: ( S )- N Preparation of -(1-Cyclopropylpiperidin-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1-cyclopropylpiperidine-4-amine, and the rest of the operation is the same.

[0049] Structural confirmation: ESI-MS / (m / z): 698.3185(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.51 (d, J = 1.5 Hz, 1H), 9.02 (s, 1H), 8.50 (d, J = 8.2 Hz, 1H), 8.05 (d, J = 2.9 Hz, 4H), 7.54 – 7.46 (m, 1H), 7.20(d, J = 8.5 Hz, 1H), 7.06 (t, J = 9.4 Hz, 1H), 4.87 (s, 1H), 4.17 (t, J = 8.9Hz, 1H), 3.86 (t, J = 7.7 Hz, 2H), 3.73 (t, J = 4.4 Hz, 5H), 3.65 (d, J = 4.5Hz, 2H), 3.00 – 2.88 (m, 6H), 2.23 (dd, J = 12.9, 10.1 Hz, 2H), 1.72 (d, J =12.3 Hz, 2H), 1.58 (d, J = 13.3 Hz, 3H), 0.41 (d, J = 6.1 Hz, 2H), 0.29 (s,2H) Example 9: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of -(1-(methanesulfonyl)piperidin-4-yl)-1H-1,2,4-triazole-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1-(methanesulfonyl)piperidine-4-amine, and the rest of the operation is the same.

[0050] Structural confirmation: ESI-MS / (m / z):728.2543(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.52 (s, 1H), 9.00 (t, J = 5.8 Hz, 1H), 8.70 (d, J = 8.3 Hz, 1H), 8.05 (d, J = 2.3 Hz, 4H), 7.56 – 7.42 (m, 1H), 7.25– 7.15 (m, 1H), 7.06 (t, J = 9.4 Hz, 1H), 4.88 (t, J = 7.2 Hz, 1H), 4.17 (t,J = 9.0 Hz, 1H), 3.97 (d, J = 8.5 Hz, 1H), 3.86 (dd, J = 9.2, 6.0 Hz, 1H),3.79 – 3.52 (m, 8H), 3.01 – 2.81 (m, 9H), 1.87 (d, J = 12.6 Hz, 2H), 1.72 (q,J = 10.8, 10.3 Hz, 2H) Example 10: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of 1,2,4-triazol-3-carboxamide (pyrimidin-2-ylmethyl)-1H-1,2,4-triazol-3-carboxamide) The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with pyrimidin-2-methylamine, and the rest of the operation is the same.

[0051] Structural confirmation: ESI-MS / (m / z): 659.2367(M+H) + ¹H NMR (400 MHz, Methanol-d4) δ 9.54 (s, 1H), 9.35 (t, J = 6.1 Hz,1H), 9.00 (t, J = 5.6 Hz, 1H), 8.69 – 8.51 (m, 3H), 8.10 – 7.99 (m, 4H), 7.49(dd, J = 15.4, 2.4 Hz, 1H), 7.23 – 7.15 (m, 1H), 7.06 (t, J = 9.3 Hz, 1H), 4.87 (t, J = 7.0 Hz, 1H), 4.65 (d, J = 6.0 Hz, 2H), 4.16 (t, J = 9.0 Hz, 1H),3.86 (dd, J = 9.2, 6.0 Hz, 1H), 3.69 (dt, J = 26.3, 4.8 Hz, 6H), 2.95 (t, J =4.6 Hz, 4H) Example 11: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of 1,2,4-triazol-3-carboxamide (pyridin-4-ylmethyl)-1H-1,2,4-triazol-3-carboxamide) The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with pyridin-4-ylmethylamine, and the rest of the operation is the same.

[0052] Structural confirmation: ESI-MS / (m / z): 658.2472(M+H) + ¹H NMR (400 MHz, Methanol-d4) δ 9.54 (s, 1H), 9.39 (d, J = 8.4 Hz,1H), 9.00 (s, 1H), 8.51 (d, J = 5.0 Hz, 2H), 8.05 (s, 4H), 7.49 (d, J = 14.9Hz, 1H), 7.31 (d, J = 5.0 Hz, 2H), 7.19 (d, J = 8.9 Hz, 1H), 7.06 (t, J = 9.5Hz, 1H), 4.88 (s, 1H), 4.50 (d, J = 6.4 Hz, 2H), 4.16 (t, J = 8.7 Hz, 1H),3.87 (d, J = 7.6 Hz, 1H), 3.69 (d, J = 28.1 Hz, 6H), 2.95 (d, J = 4.4 Hz, 4H) Example 12: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of 1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 2-(pyridin-3-yl)ethylamine, and the rest of the operation is the same.

[0053] Structural confirmation: ESI-MS / (m / z): 659.2523(M+H) + ¹H NMR (400 MHz, Methanol-d4) δ 9.50 (s, 1H), 9.03 (d, J = 5.9 Hz,1H), 8.86 (d, J = 6.2 Hz, 1H), 8.57 (d, J = 19.8 Hz, 1H), 8.18 – 7.86 (m,4H), 7.64 – 7.40 (m, 2H), 7.19 (d, J = 8.9 Hz, 1H), 7.06 (t, J = 9.3 Hz, 1H), 4.96 – 4.80 (m, 1H), 4.16 (t, J = 9.1 Hz, 1H), 3.86 (d, J = 7.3 Hz, 1H), 3.80– 3.53 (m, 9H), 2.95 (d, J = 5.9 Hz, 5H) Example 13: ( S )- N Preparation of -(3,5-difluorobenzyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 3,5-difluorobenzylamine, and the rest of the operation is the same.

[0054] Structural confirmation: ESI-MS / (m / z): 685.2389(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.54 (d, J = 2.4 Hz, 1H), 9.44 – 9.37 (m,1H), 9.02 (q, J = 6.6, 6.1 Hz, 1H), 8.12 – 7.99 (m, 4H), 7.49 (dd, J = 14.9,3.0 Hz, 1H), 7.19 (d, J = 8.9 Hz, 1H), 7.15 – 7.00 (m, 4H), 4.87 (q, J = 6.4Hz, 1H), 4.49 (d, J = 6.2 Hz, 2H), 4.16 (t, J = 9.1 Hz, 1H), 3.86 (q, J =8.5, 7.1 Hz, 1H), 3.78 – 3.61 (m, 6H), 3.00 – 2.87 (m, 4H) Example 14: (S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)- N Preparation of 1,2,4-triazol-3-carboxamide The method of Example 1 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with thiophene-3-ylmethylamine, and the rest of the operation is the same.

[0055] Structural confirmation: ESI-MS / (m / z): 644.2135(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.53 (s, 1H), 9.23 (s, 1H), 9.01 (s, 1H), 8.05 (s, 4H), 7.50 (d, J = 12.1 Hz, 2H), 7.33 (s, 1H), 7.20 (d, J = 8.9 Hz, 1H), 7.14 – 7.02 (m, 2H), 4.88 (s, 1H), 4.47 (d, J = 6.2 Hz, 2H), 4.17 (t, J = 8.9 Hz, 1H), 3.86 (d, J = 2.0 Hz, 1H), 3.69 (d, J = 29.9 Hz, 6H), 2.95 (s,4H) Example 15: ( S )- N Preparation of -(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide The preparation was carried out according to the synthetic route of linezolid derivative containing pyridazinone ring, as described in Route 2: 4-aminobenzoic acid (3.0 g, 21.9 mmol) was used as the starting material and dissolved in 10 ml of 10% HCl solution in an ice bath at 0–5 °C. Sodium nitrite (1.8 g, 26.1 mmol) was added and stirred for 0.5–1 hour to complete diazotization, yielding a diazonium salt. The obtained diazonium salt did not need to be separated and was directly added to ethyl acetoacetate (2.82 g, 21.7 mmol) and ammonium acetate (16.8 g, 218 mmol). The mixture was stirred at room temperature to carry out a coupling reaction, constructing an intermediate containing a hydrazone bond and isomerizing it to a more thermodynamically stable Z-configuration, yielding intermediate Y2. Y2 was dissolved in 20 mL of acetonitrile, and TCFH (6.0 g, 21.9 mmol) and NMI (2.16 g, 26.3 mmol) were added. The mixture was stirred at room temperature until the carboxyl group was fully activated (as monitored by TLC). Then, (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one (7.42 g, 24.1 mmol) was added to form an amide bond, yielding intermediate Y3. Y3 was reacted with ethyl (triphenylphosphine) acetate (61.0 g, 175 mmol) and 100 mL of a 1:1 mixture of N,N-dimethylformamide and N,N-dimethylacetamide in a Wittig reaction at 100 °C. The reaction proceeded via a four-membered ring transition state to form a carbon-carbon double bond, yielding intermediate Y4. Y4 was dissolved in 30 mL of a methanol-water (1:10) mixture, and lithium hydroxide monohydrate (1.20 g, 28.5 mmol) was added. The mixture was stirred at room temperature until the ester bond was completely hydrolyzed (monitored by TLC). The solution was then acidified with dilute hydrochloric acid to pH ≈ 3 to obtain the key intermediate Y5. Y5 was then dissolved again in 10 mL of acetonitrile, and TCFH (6.0 g, 21.9 mmol) and NMI (2.16 g, 26.3 mmol) were added to activate the carboxyl group. The carboxyl group was then reacted with 4-aminothiophene-2-onitrile (26.3 mmol, the exact mass adjusted according to the molecular weight of the selected amine) at room temperature to form a new amide bond. The final target compound was obtained by column chromatography purification. The yield of the final product was 82%, and the purity was 92%.

[0056] Route 2: Preparation of linezolid derivatives containing pyridazinone rings: .

[0057] Structural confirmation: ESI-MS / (m / z): 683.2174(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.98 (t, J = 6.0 Hz, 1H), 8.15 (s, 1H), 7.98 (d, J = 8.6 Hz, 3H), 7.82 (d, J = 8.2 Hz, 2H), 7.49 (d, J = 15.1 Hz,1H), 7.19 (d, J = 9.0 Hz, 1H), 7.06 (d, J = 8.1 Hz, 2H), 4.88 (t, J = 7.5 Hz,1H), 4.16 (t, J = 8.9 Hz, 1H), 3.86 (t, J = 7.7 Hz, 1H), 3.80 – 3.58 (m, 7H),3.44 (d, J = 7.1 Hz, 1H), 2.95 (t, J = 4.4 Hz, 4H), 2.42 (s, 3H) Example 16: 1-(4-(((() S )-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl- N Preparation of 1-(1-(methylsulfonyl)pyrrolidone-3-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1-(methanesulfonyl)pyrrolidine-3-amine, and the rest of the operation is the same.

[0058] Structural confirmation: ESI-MS / (m / z): 724.2308(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.84 (d, J = 6.6 Hz, 1H), 8.59 (s, 1H), 7.98 (d, J = 7.9 Hz, 3H), 7.75 (d, J = 8.4 Hz, 3H), 7.19 (d, J = 9.6 Hz, 1H), 6.82 (t, J = 9.3 Hz, 1H), 6.43 (d, J = 14.9 Hz, 1H), 6.35 (d, J = 8.7 Hz, 1H), 5.55 (s, 1H), 5.10 (d, J = 5.0 Hz, 1H), 4.42 (q, J = 6.2 Hz, 1H), 4.31(q, J = 7.2 Hz, 1H), 4.16 (t, J = 9.0 Hz, 1H), 3.84 (d, J = 6.1 Hz, 2H), 3.76– 3.64 (m, 6H), 3.53 (dd, J = 10.5, 6.7 Hz, 1H), 3.21 – 3.06 (m, 3H), 2.95(d, J = 6.0 Hz, 3H), 2.90 (s, 3H), 2.32 (s, 3H), 2.17 (dd, J = 13.1, 6.6 Hz,1H), 2.03 – 1.89 (m, 2H) Example 17: ( S )- N Preparation of -(2-cyclohexylethyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 2-cyclohexylethylamine, and the rest of the operation is the same.

[0059] Structural confirmation: ESI-MS / (m / z):709.3237(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.56 (d, J = 13.7 Hz, 1H), 7.97 (d, J =8.5 Hz, 2H), 7.77 (d, J = 8.4 Hz, 2H), 6.99 (s, 1H), 6.82 (t, J = 9.3 Hz,1H), 6.50 – 6.32 (m, 2H), 5.55 (s, 1H), 5.09 (d, J = 5.2 Hz, 1H), 3.76 (d, J= 58.1 Hz, 6H), 3.10 (s, 2H), 3.00 – 2.76 (m, 5H), 2.32 (s, 3H), 1.82 – 1.52(m, 5H), 1.49 – 1.03 (m, 7H), 0.88 (d, J = 12.6 Hz, 2H) Example 18: ( S )- N Preparation of -(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1,1-dioxotetrahydro-2H-thiopyran-4-amine, and the rest of the operation is the same.

[0060] Structural confirmation: ESI-MS / (m / z): 737.2559(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.95 (t, J = 6.0 Hz, 1H), 8.68 (d, J =8.1 Hz, 1H), 7.95 (d, J = 8.4 Hz, 2H), 7.77 (d, J = 8.4 Hz, 2H), 7.49 (dd, J= 14.9, 2.5 Hz, 1H), 7.26 – 7.13 (m, 1H), 7.13 – 6.93 (m, 2H), 4.87 (dd, J =8.8, 5.4 Hz, 1H), 4.16 (t, J = 9.0 Hz, 2H), 3.85 (dd, J = 9.2, 5.9 Hz, 1H),3.69 (dt, J = 27.5, 5.0 Hz, 6H), 3.31 (s, 2H), 3.08 (d, J = 14.0 Hz, 2H), 2.95 (t, J = 4.6 Hz, 4H), 2.31 (d, J = 1.2 Hz, 3H), 2.17 – 1.97 (m, 4H) Example 19: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl- N Preparation of -((1-methyl-1H-pyrazol-4-yl)methyl)-6-oxo-1,6-dihydropyridazine-3-carboxamide (S6) The method of Example 15 was followed, except that the 4-aminothiophene-2-nitrile in the last step was replaced with (1-methyl-1H-pyrazol-4-yl)methylamine, and the rest of the operation was the same, to obtain the target compound S6.

[0061] Structural confirmation: ESI-MS / (m / z): 677.2582(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.93 (dt, J = 23.6, 5.9 Hz, 2H), 7.95 (d,J = 8.4 Hz, 2H), 7.78 (d, J = 8.4 Hz, 2H), 7.59 (s, 1H), 7.50 (dd, J = 15.0,2.5 Hz, 1H), 7.34 (s, 1H), 7.26 – 7.16 (m, 1H), 7.13 – 6.96 (m, 2H), 4.87 (t,J = 6.7 Hz, 1H), 4.29 – 4.11 (m, 3H), 3.86 (dd, J = 9.0, 6.1 Hz, 1H), 3.78(s, 3H), 3.69 (dt, J = 30.5, 5.1 Hz, 6H), 2.95 (t, J = 4.7 Hz, 4H), 2.34 (s,3H) Example 20: ( S )-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo- N Preparation of 3-(2-(thiophen-2-yl)ethyl)-1,6-dihydropyridazine-3-carboxamide The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 2-(thiophene-2-yl)ethylamine, and the rest of the operation is the same.

[0062] Structural confirmation: ESI-MS / (m / z): 686.2453(M+H) + ¹H NMR (400 MHz, Methanol-d4) δ 7.85 (d, J = 8.6 Hz, 2H), 7.65 (d, J= 8.5 Hz, 2H), 7.42 (d, J = 14.4 Hz, 1H), 7.21 – 7.01 (m, 3H), 6.96 – 6.74(m, 4H), 4.88 (s, 1H), 4.08 (t, J = 8.9 Hz, 1H), 3.83 (d, J = 7.4 Hz, 6H), 3.63 (t, J = 8.2 Hz, 2H), 3.16 – 2.95 (m, 5H), 2.57 (s, 3H) Example 21: Preparation of (S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 5-cyclopropyl-1H-pyrazole-3-amine, and the rest of the operation is the same.

[0063] Structural confirmation: ESI-MS / (m / z): 687.2634(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.95 (s, 1H), 8.02 – 7.87 (m, 2H), 7.77(ddd, J = 8.0, 5.7, 2.0 Hz, 2H), 7.55 – 7.44 (m, 1H), 7.20 (d, J = 8.9 Hz,1H), 7.13 – 6.93 (m, 2H), 4.88 (s, 1H), 4.21 – 4.12 (m, 1H), 3.86 (t, J = 7.8Hz, 1H), 3.80 – 3.58 (m, 6H), 3.10 (dd, J = 7.6, 5.3 Hz, 1H), 3.04 – 2.86 (m,4H), 2.28 (d, J = 13.5 Hz, 4H), 2.04 – 1.75 (m, 3H), 1.63 (d, J = 11.7 Hz,3H), 1.37 (d, J = 10.5 Hz, 1H), 1.18 (td, J = 7.3, 1.9 Hz, 1H) Example 22: Preparation of (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(1-(1-(methylsulfonyl)piperidin-4-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide) The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with 1-(methanesulfonyl)piperidine-4-amine, and the rest of the operation is the same.

[0064] Structural confirmation: ESI-MS / (m / z): 738.2659(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 8.96 (s, 1H), 8.60 (d, J = 8.0 Hz, 1H), 7.95 (d, J = 8.2 Hz, 2H), 7.76 (d, J = 8.2 Hz, 2H), 7.49 (d, J = 14.7 Hz,1H), 7.19 (d, J = 8.7 Hz, 1H), 7.12 – 6.96 (m, 2H), 4.87 (s, 1H), 4.16 (t, J= 9.0 Hz, 1H), 3.95 – 3.46 (m, 11H), 3.03 – 2.80 (m, 9H), 2.31 (s, 3H), 1.89(d, J = 12.9 Hz, 2H), 1.55 (d, J = 12.2 Hz, 2H) Example 23: Preparation of (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyrimidin-2-ylmethyl)-1,6-dihydropyridazine-3-carboxamide) The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with pyrimidin-2-methylamine, and the rest of the operation is the same.

[0065] Structural confirmation: ESI-MS / (m / z): 689.2478(M+H) + ¹H NMR (400 MHz, Methanol-d4) δ 8.61 (s, 1H), 8.45 (q, J = 2.7 Hz,2H), 8.16 (t, J = 5.8 Hz, 1H), 7.81 (d, J = 8.3 Hz, 2H), 7.67 (t, J = 6.1 Hz,1H), 7.61 (d, J = 8.3 Hz, 2H), 7.36 (dd, J = 14.3, 2.5 Hz, 1H), 7.02 (dd, J =8.8, 2.5 Hz, 1H), 6.91 – 6.78 (m, 2H), 4.80 (qt, J = 6.6, 3.4 Hz, 1H), 4.70(d, J = 5.8 Hz, 2H), 4.01 (t, J = 8.9 Hz, 1H), 3.87 – 3.73 (m, 6H), 3.66 (dt,J = 13.8, 6.2 Hz, 1H), 2.98 (t, J = 4.6 Hz, 4H), 2.80 (s, 1H), 2.54 (s, 3H) Example 24: Preparation of (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyridin-4-ylmethyl)-1,6-dihydropyridazine-3-carboxamide) The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with pyridin-4-ylmethylamine, and the rest of the operation is the same.

[0066] Structural confirmation: ESI-MS / (m / z): 688.2583(M+H) + ¹H NMR (400 MHz, Chloroform-d) δ 8.56 – 8.50 (m, 2H), 7.83 (d, J =8.2 Hz, 2H), 7.76 (t, J = 6.4 Hz, 1H), 7.62 (d, J = 8.3 Hz, 2H), 7.40 (dd, J= 14.4, 2.6 Hz, 1H), 7.22 (d, J = 4.9 Hz, 3H), 7.04 (dd, J = 9.1, 2.5 Hz,1H), 6.93 – 6.83 (m, 2H), 4.83 (d, J = 6.0 Hz, 1H), 4.58 (d, J = 6.2 Hz, 2H),4.04 (t, J = 8.9 Hz, 1H), 3.84 (t, J = 4.7 Hz, 5H), 3.74 (ddt, J = 26.7,13.7, 6.2 Hz, 2H), 3.02 (t, J = 4.6 Hz, 4H), 2.59 (s, 3H) Example 25: Preparation of (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(thiophene-3-ylmethyl)-1,6-dihydropyridazine-3-carboxamide) The method of Example 15 is followed, except that the 4-aminothiophene-2-nitrile in the last step is replaced with thiophene-3-ylmethylamine, and the rest of the operation is the same.

[0067] Structural confirmation: ESI-MS / (m / z): 672.2246(M+H) + ¹H NMR (400 MHz, DMSO-d6) δ 9.09 (d, J = 7.0 Hz, 1H), 8.97 (s, 1H), 7.95 (d, J = 8.3 Hz, 2H), 7.84 – 7.74 (m, 2H), 7.49 (d, J = 11.0 Hz, 2H),7.32 (s, 1H), 7.19 (d, J = 9.0 Hz, 1H), 7.10 – 6.95 (m, 3H), 4.87 (s, 1H),4.50 – 4.31 (m, 3H), 4.16 (t, J = 8.6 Hz, 1H), 3.85 (s, 1H), 3.68 (d, J =33.0 Hz, 6H), 2.95 (s, 4H), 2.35 (s, 3H) Effect verification I. Verification of in vitro antibacterial activity The linezolid derivatives prepared in various embodiments of the present invention were subjected to in vitro inhibitory activity tests against Gram-positive bacteria (Staphylococcus aureus ATCC6538, Staphylococcus epidermidis ATCC12228, and methicillin-resistant Staphylococcus aureus MRSAATCC43300). Using Linezolid as a control, the minimum inhibitory concentration (MIC) was determined using the micro-broth two-fold dilution method. The specific experimental steps are as follows: (1) After the test strain was revived, it was inoculated into LB broth medium and cultured at 37℃ with shaking at 180 r / min for 16-18 h until the logarithmic growth phase. The bacterial culture was then diluted with LB broth medium and the bacterial concentration was adjusted to 10 using the McFarland turbidimetric method. 6 CFU / mL, for later use. In a 96-well plate, except for the top, bottom, and leftmost blank wells (without bacterial culture), add 180 μL of diluted bacterial culture to the remaining wells. Place the 96-well plate in an incubator and pre-incubate at 37°C for 2 hours.

[0068] (2) Dissolve the test sample in 20 μL of dimethyl sulfoxide and add 980 μL of LB broth medium to dissolve the sample into a 1 mg / mL solution. Then, perform serial dilutions of the sample in EP tubes to obtain concentration gradients of 1, 0.333, 0.111, 0.037, and 0.012 μg / mL. Set up 3 replicates for each concentration, add 20 μL of the solution to each well (the two rows and two columns of wells around the bottom are blank wells, with only bacterial solution and medium added), and incubate the 96-well plate at 37°C for 24 h.

[0069] (3) After the culture is completed, observe and record the bacterial growth in each well. The lowest drug concentration at which no bacterial growth occurs is taken as the MIC value of the compound. If the liquid in the well is clear, it indicates that bacterial growth is inhibited; if the liquid is turbid, it indicates that the bacteria are growing normally. At the same time, a blank control (only culture medium is added) and a positive control (bacterial solution, culture medium and Ceritinib are added) are set up for result calibration.

[0070] The compound against Staphylococcus aureus ( S.aureus ATCC6538, Bacillus subtilis ( B.Subtilis ATCC6633, Staphylococcus epidermidis ( S.Epidermidis ATCC12228, methicillin-resistant Staphylococcus aureus (ATCC12228, methicillin-resistant Staphylococcus aureus) MRSA The antibacterial activity results of ATCC43300 are shown in Table 2.

[0071] Table 2: Antibacterial activity (MIC determination) of some examples The above experimental results show that the compound of general formula I protected by this invention has good in vitro antibacterial activity, and Example 19 exhibits excellent antibacterial effects against both Staphylococcus epidermidis and Staphylococcus aureus. Specifically, Example 19 showed a minimum inhibitory concentration (MIC) of 0.5 μg / mL against Staphylococcus epidermidis, with significantly better antibacterial activity than the positive control drug Linezolid (MIC = 1 μg / mL), doubling the antibacterial efficacy and demonstrating a strong inhibitory ability against Staphylococcus epidermidis. Meanwhile, Example 19 had an MIC of 1 μg / mL against Staphylococcus aureus, comparable to the antibacterial activity of the positive control drug Linezolid, effectively inhibiting the growth of Staphylococcus aureus and reaching the in vitro antibacterial level of a first-line clinical drug.

[0072] II. Evaluation of Hemolytic Toxicity Hemolytic toxicity of the preferred compound Example 19 was evaluated. Hemolytic toxicity is a core indicator for evaluating the effect of antibacterial compounds on erythrocyte membrane stability and blood compatibility. The hemolytic risk of Example 19 at different concentrations was assessed through an in vitro hemolysis experiment system, providing a safety basis for subsequent in vivo animal experiments and clinical applications.

[0073] Hemolytic toxicity evaluation experimental procedure (1) Take 1.5 mL of 2% sheep red blood cell suspension and centrifuge to obtain pure red blood cells. (2) Add 0.9% physiological saline to the red blood cells for resuspending, and then add the test solution of Example 19 with gradient concentrations respectively. Vortex thoroughly to ensure uniform dispersion. (3) Place the above system incubate at 37℃ for 1 h, and use a UV spectrophotometer to measure the absorbance value A at 540 nm. Calculate the hemolysis rate according to the following formula: Hemolysis rate (%) = (A experimental group - A negative control group) / (A positive control group - A negative control group) × 100%.

[0074] Figure 1 The hemolytic safety evaluation results for Example 19 are shown below (the x-axis represents the corresponding concentration (μg / mL) of Example 19 at 8, 16, 32, 64, 128, and 256, and X-100 represents Triton X-100). Figure 1 The images shown are direct photographs of the hemolysis experiment (corresponding one-to-one with the horizontal axis from left to right). The results show that Example 19 exhibited a hemolysis rate of only 6.27% at a concentration of 16 μg / mL. The hemolysis rate increased slowly with increasing compound concentration, but all tested concentrations showed a hemolysis rate below 7%, far below the safety threshold of 10%. These results indicate that Example 19 has extremely weak erythrocyte membrane-damaging effects within its effective antibacterial concentration range and possesses excellent blood compatibility. This is mainly due to the synergistic effect of the morpholine ring, fluorobenzene ring, and polar pyridazinone fragment in its structure, which significantly reduces non-specific damage to the cell membrane. The low hemolytic toxicity confirms that Example 19 has high safety for in vivo application and can be used for subsequent in vivo antibacterial and toxicity experiments.

[0075] III. KM Mouse Toxicity Test The KM mouse toxicity test is a key step in the preclinical safety evaluation of antibacterial drugs. It comprehensively assesses the effects of Example 19 on the overall condition, liver and kidney function, and organ tissues of animals, and determines the safe dosage range.

[0076] Detailed operating steps (1) Experimental grouping: SPF-grade KM mice were ear-tagged and randomly divided into 4 groups of 4 mice each: blank control group (control, physiological saline), positive control group (Linezolid 100 mg / kg), low-dose group (50 mg / kg) of Example 19, and high-dose group (100 mg / kg) of Example 19. (2) Gavage administration: The administration interval was 24 h / time. The positive group and low-dose group were administered 50 mg / kg, and the high-dose group was administered 100 mg / kg. The solvent was physiological saline. The blank group was given an equal volume of physiological saline. (3) Sample collection: After 7 days of continuous administration, no less than 0.5 mL of blood was collected from the eyeballs of the mice and placed in a 1.5 mL EP tube. The blood was kept at 4℃ for later use. Two mice in each group were randomly dissected, and the heart, liver, spleen, lungs, and kidneys were removed and stored in 4% paraformaldehyde fixative at 4℃ for later use.

[0077] Mouse blood sample analysis (1) Blood sample processing: Centrifuge at 15000 r / min for 10 min in a 4℃ low-temperature centrifuge, take the supernatant, and repeat centrifugation until 200µL of pure serum is obtained. (2) Biochemical detection: Take 150µL of serum and add it to the blood sample analysis reagent tray. Place it in a fully automated multifunctional biochemical analyzer to perform preoperative testing of ten indicators, record and analyze key indicators such as ALT (alanine aminotransferase), AST (aspartate aminotransferase), CREA (creatinine), TP (total protein), UREA (urea), GLU (glucose), LDH (lactate dehydrogenase), ALP (alkaline phosphatase), and CK (creatine kinase).

[0078] HE staining experiment (1) Tissue processing: Rinse organs with physiological saline and dry surface moisture, fix with 4% formaldehyde for 24 h, and dehydrate sequentially with 50%, 70%, 80%, 90%, and 100% ethanol, 1 h for each step. (2) Clearing and paraffin infiltration: Clear the dehydrated tissue twice with xylene, 15 min each time; then immerse in molten paraffin for 2 h. (3) Dewaxing of sections: Treat paraffin sections sequentially with xylene I, xylene II, anhydrous ethanol I, anhydrous ethanol II, and 75% ethanol for 20 min, 20 min, 5 min, 5 min, and 5 min respectively, and rinse with tap water. (4) Hematoxylin staining: Stain with hematoxylin solution for 3-5 min, rinse with tap water, differentiate with differentiation solution, re-blue with blue solution, and rinse with running water. (5) Eosin staining: Dehydrate sections with 85% and 95% ethanol for 5 min each, and stain with eosin solution for 5 min. (6) Dehydration and mounting: The sections are dehydrated by gradient dehydration with anhydrous ethanol, cleared with xylene, and mounted with neutral resin. (7) Microscopic examination: The morphology of organs and tissues is observed under a microscope, photographed and recorded, and pathological damage is analyzed.

[0079] The results of in vivo toxicity experiments in each group of KM mice are shown below. Figure 2 (A: ALT, AST, CREA; B: TP, UREA, GLU; C: LDH, ALP, CK), organ HE staining results are shown in [reference needed]. Figure 3 The results showed that mice in both the blank control group and the Example 19 treatment group experienced steady weight gain without death, diarrhea, lethargy, or other abnormal reactions. Liver function indicators (ALT, AST), kidney function indicators (CREA, UREA), metabolic indicators (GLU, TP), and myocardial enzyme profiles (LDH, CK) remained within normal physiological ranges in both the low-dose and high-dose groups of Example 19. The high-dose group showed only slight fluctuations with no statistically significant differences. HE staining results indicated that the heart, liver, spleen, lung, and kidney tissues of mice in the Example 19 treatment group were structurally intact with normal cell morphology. In the high-dose group, only very slight edema was observed in the liver and kidneys, without necrosis, inflammatory infiltration, or significant pathological damage. Overall, the results confirmed that Example 19, at an effective antibacterial dose, had no significant acute toxicity in mice, and its liver and kidney function and organ structure were unaffected. Its safety profile was significantly better than the positive control group, demonstrating good potential for drug development.

[0080] IV. Time-based sterilization kinetics test The time-based sterilization curve method was used to evaluate the pair of products in Example 19. S.aureus The bactericidal kinetics of Staphylococcus aureus and MRSA (methicillin-resistant Staphylococcus aureus) were investigated to clarify their bactericidal rate and concentration dependence.

[0081] Experimental operation steps (1) Staphylococcus aureus (ATCC6538) and MRSA (ATCC43300) were cultured to the logarithmic growth phase, and the bacterial concentration was adjusted to 1×10⁻⁶. 6 CFU / mL. (2) Dilute Example 19 with culture medium to four concentration gradients of 0.5×MIC, 1×MIC, 2×MIC, and 4×MIC, and mix with an equal volume of bacterial solution. (3) Incubate at 37℃ in a shaker, and take samples at 0, 2, 4, 6, and 8 h respectively, dilute and spread on LB solid medium. (4) Count the colonies after 24 h of incubation and calculate log. 10 CFU / mL, plot the time-based sterilization curve.

[0082] Figure 4 This is a time-killing kinetic curve of Staphylococcus aureus in Example 19.

[0083] Figure 5 This is a time-based bactericidal kinetic diagram of Staphylococcus aureus in Example 19.

[0084] Figure 6 This is a time-based bactericidal kinetic curve of methicillin-resistant Staphylococcus aureus in Example 19.

[0085] Figure 7This is a time-based bactericidal kinetic diagram of methicillin-resistant Staphylococcus aureus in Example 19.

[0086] The time-killing kinetics results of Example 19 are shown in [the original text]. Figures 4-7 The results showed that Example 19 exhibited significant concentration-dependent rapid bactericidal activity against both Staphylococcus aureus and MRSA: at a concentration of 4×MIC, both Staphylococcus aureus and MRSA were completely killed within 8 hours, reducing the colony count to 0; at a concentration of 2×MIC, significant bactericidal activity was achieved within 6-8 hours; and concentrations of 1×MIC and below showed bacteriostatic activity. Example 19 demonstrated rapid and thorough bactericidal action, superior to the antibacterial properties of linezolid, and possessed the characteristics of a potent bactericide.

[0087] V. Evaluation of bacterial cell membrane integrity (nucleic acid leakage test) The disruptive effect of Example 19 on the integrity of bacterial cell membranes was verified through a nucleic acid leakage experiment, thus clarifying its antibacterial target.

[0088] Experimental operation steps (1) MRSA was cultured to the logarithmic growth phase, and different concentrations of Example 19 (2, 4, 8, 16, 32 μg / mL) were added and incubated at 37℃ for 4 h. (2) Centrifuged at 5000 r / min for 10 min, the supernatant was collected, and the bacterial cells were removed. (3) 1.2% agarose gel was prepared, stained with EB, and 10 μL of the supernatant was used for agarose gel electrophoresis at 120 V for 30 min. (4) The nucleic acid bands were observed using a gel imaging system to determine the degree of cell membrane damage.

[0089] See results Figure 8 As the concentration of Example 19 increased, the nucleic acid bands in the supernatant gradually became brighter and wider. The high concentration (32 μg / mL) group showed obvious nucleic acid leakage bands, confirming that Example 19 killed the bacteria by disrupting the integrity of the bacterial cell membrane, causing the leakage of intracellular genetic material.

[0090] VI. Ultramorphological observation of bacteria (scanning electron microscopy, SEM) Scanning electron microscopy was used to visually observe the changes in bacterial morphology and structure after treatment in Example 19, and to verify the cell membrane damage mechanism.

[0091] Experimental operation steps (1) Staphylococcus aureus and MRSA were treated for 4 h using the methods described in Example 19 (1×MIC, 2×MIC, 4×MIC), and the bacterial cells were collected. (2) The bacteria were fixed overnight in 2.5% glutaraldehyde at 4°C, dehydrated with graded ethanol, critically dried, and sputtered with gold. (3) The surface morphology, cell membrane integrity, bacterial shrinkage and rupture were observed by scanning electron microscopy and compared with the untreated control group.

[0092] Figure 9 The images show a comparison of SEM images after treatment with Staphylococcus aureus in Example 19. In the images, A represents the control group, B represents the 1×MIC group, C represents the 2×MIC group, and D represents the 4×MIC group.

[0093] Figure 10 The images shown are SEM images after MRSA processing in Example 19. In the images, A represents the blank group, B represents the 1×MIC group, C represents the 2×MIC group, and D represents the 4×MIC group.

[0094] See results Figure 9-10 The bacteria in the blank group were plump, smooth, and structurally intact; the bacteria in the treatment group of Example 19 showed obvious shrinkage, depression, cell membrane rupture, and leakage of contents. The bacteria in the high concentration group ruptured and disintegrated over a large area, which directly confirmed that Example 19 exerted its bactericidal effect by destroying the cell membrane structure.

[0095] VII. Evaluation of the therapeutic activity of preferred compounds in vivo for Staphylococcus aureus infection in Example 19 1. Laboratory animals and bacterial strains SPF grade KM mice, 4-5 weeks old, female, weighing 23-27g; Staphylococcus aureus (S. aureus ATCC6538).

[0096] 2. Experimental grouping and drug administration Thirty mice were randomly divided into five groups of six each: a model control group (saline), a positive control group (linezolid 40 mg / kg), a low-dose group (20 mg / kg) as described in Example 19, a medium-dose group (40 mg / kg) as described in Example 19, and a high-dose group (60 mg / kg) as described in Example 19. Mice were injected intraperitoneally with 10 mg / kg of saline solution. 8 A peritoneal infection model was established using CFU / mL Staphylococcus aureus bacterial suspension. The first dose was administered 5 minutes after infection, followed by doses every 6 hours for a total of 6 doses.

[0097] 3. Observation Indicators Mice were observed daily for their mental state, activity level, coat luster, and body weight. After drug administration, blood was collected from the eyeballs, and serum was separated to detect liver and kidney function biochemical indicators. The heart, liver, spleen, lungs, and kidneys were dissected, fixed in 4% paraformaldehyde, and subjected to HE staining and histopathological observation. Immunohistochemistry was used to detect the expression levels of IL-1β, IL-6, and TNF-α inflammatory factors in liver and kidney tissues.

[0098] 4. Experimental Results (1) General condition and weight changes In the model control group, mice exhibited lethargy, reduced activity, and continuous weight loss. In Example 19, the mental state and activity of mice in each dose group and the positive control group gradually recovered, and their weight showed a steady upward trend. The high-dose group (60 mg / kg) showed the best recovery effect, comparable to the linezolid group.

[0099] (2) Serum biochemical indicators Compared with the model control group, the liver function indicators (ALT, AST, ALP), kidney function indicators (CREA, UREA), and tissue damage markers (LDH, CK) of mice in each dose group of Example 19 were significantly reduced in a dose-dependent manner. The indicators in the high-dose group were close to normal physiological levels and there was no obvious liver and kidney toxicity.

[0100] (3) Histopathological observation of organs In the model control group, the liver and kidney tissues of mice showed obvious pathological damage such as inflammatory infiltration, cell edema, and necrosis. In Example 19, the pathological damage in the low- and medium-dose groups was significantly reduced, and the liver and kidney tissues in the high-dose group had intact structure, normal cell morphology, and no obvious inflammation or necrosis, which was consistent with the effect of the positive control group.

[0101] (4) Expression of inflammatory factors Immunohistochemical results showed that Example 19 could significantly downregulate the expression levels of IL-1β, IL-6, and TNF-α in the liver and kidney tissues of infected mice. The inhibitory effect increased with increasing dose. The inhibition rate of the three inflammatory factors in the high-dose group was not significantly different from that in the linezolid group, and it could effectively alleviate the systemic inflammatory response caused by bacterial infection.

[0102] 5. Conclusion Figure 11 This is a statistical analysis of the treatment effects of the KM mouse infection model in Example 19.

[0103] Figure 12 HE staining results of in vivo organs from the KM mouse infection model in Example 19.

[0104] Figure 13 This is a morphological observation of liver tissue in mice after treatment with bacterial infection, as described in Example 19.

[0105] Figure 14 The effect of Example 19 on the expression of IL-1, IL-6, and TNF-α in the liver of mice infected with bacteria.

[0106] Figure 15 The immunohistochemical results for the expression of IL-1, IL-6, and TNF-α in the liver of bacterial-infected mice are shown in Example 19.

[0107] Figure 16 This is a morphological observation of liver tissue in mice after treatment with bacterial infection, as described in Example 19.

[0108] Figure 17 The effect of Example 19 on the expression of IL-1, IL-6, and TNF-α in the kidneys of mice infected with bacteria.

[0109] Figure 18 The immunohistochemical results for the expression of IL-1, IL-6, and TNF-α in the kidneys of bacterial-infected mice are shown in Example 19.

[0110] like Figure 11-18 Example 19 shows that it has a significant in vivo therapeutic effect on Staphylococcus aureus peritoneal infection in mice. It can effectively improve the clinical symptoms of infected mice, protect liver and kidney function, reduce organ pathological damage, and inhibit the release of inflammatory factors. It is significantly dose-dependent. The in vivo antibacterial efficacy of high dose (60mg / kg) is comparable to that of linezolid, while having good in vivo safety. It can be further developed as a candidate drug for anti-Staphylococcus aureus infection.

[0111] Examples of application formulations Application Example 1: Tablets Take 10g of the compound from Example 1, add 20g of excipients (15g lactose, 3g sodium carboxymethyl starch, and 2g magnesium stearate) according to the general pharmaceutical tableting method, mix well, pass through an 80-mesh sieve, dry, and compress into 100 tablets, each weighing 300mg (containing 100mg of the active ingredient).

[0112] Application Example 2: Capsules Take 5g of the compound from Example 19, mix it with 10g of excipients (6g of microcrystalline cellulose, 3g of talc, and 1g of silicon dioxide) according to the requirements of pharmaceutical capsules, pass it through a 60-mesh sieve, and fill it into No. 1 empty capsules. Each capsule weighs 300mg (containing 50mg of the active ingredient).

[0113] Application Example 3: Ointment Take 10g of the compound from Example 12, grind it into a fine powder, and then grind it evenly with 500g of oily matrix such as petrolatum (450g of petrolatum and 50g of lanolin). Grind it into a fine and uniform powder using a three-roll mill to obtain an ointment (containing 2% of the active ingredient).

[0114] Application Example 4: Aerosol Take 10g of the compound from Example 15, dissolve it in 50mL of propylene glycol, add 400mL of distilled water and other excipients (5g of polysorbate 80 and 0.5g of benzalkonium chloride), stir to dissolve, filter until clear, add distilled water to make up to 500mL, fill into a pressure-resistant aerosol can, and press in a propellant (a Freon substitute) to obtain the final product.

[0115] Application Example 5: Suppositories Take 10g of the compound from Example 20, grind it finely, add 20g of glycerin, grind evenly, then add 80g of melted glycerin-gelatin matrix (30g glycerin, 20g gelatin, 30g distilled water), grind evenly, pour into a suppository mold coated with lubricant (liquid paraffin), cool and solidify, scrape it flat, and demold to obtain 50 suppositories (each containing 200mg of the active ingredient).

[0116] Application Example 6: Droplets Take 5g of the compound from Example 22 and 25g of matrix such as gelatin (15g gelatin, 10g polyethylene glycol 6000). Heat to 60°C to melt and mix. Then, drop the mixture into low-temperature liquid paraffin (temperature 0-5°C) through a pelleting machine. After cooling and solidification, collect the pellets and remove the surface paraffin. A total of 1000 pellets (each pellet containing 5mg of the active ingredient) were obtained.

[0117] Application Example 7: Topical Liniment Take 10g of the compound from Example 23, mix and grind it with 2.5g of excipients such as emulsifier (1g sodium dodecyl sulfate, 1.5g glyceryl monostearate) according to conventional pharmaceutical methods, add distilled water to 200mL, stir and emulsify until uniform and clear, and you will get the topical liniment (containing 5% of the active ingredient).

[0118] Application Example 8: Injectable Take 6g of the compound from Example 26, add 150mL of distilled water for injection according to conventional pharmaceutical methods, stir to dissolve, add 0.3g of activated carbon to adsorb impurities, stir for 30min, filter through a 0.65μm microporous membrane, add distilled water for injection to make up to 200mL of the filtrate, purge with nitrogen for protection, fill into 2mL ampoules, sterilize (121℃, 15min) to prepare an aqueous injection preparation, fill a total of 100 bottles (each bottle contains 60mg of the active ingredient).

[0119] Application Example 9: Film Formulation Take 6g of the compound from Example 28, add 15g of polyvinyl alcohol, 3g of pharmaceutical glycerin and 50mL of distilled water, stir until expanded, heat to 80°C to dissolve, filter through an 80-mesh sieve, add the compound from Example 28 to the filtrate and stir until dissolved, pour onto the stainless steel plate of a coating machine, control the thickness to 0.2mm, dry in a 60°C drying oven to form a film, and cut into 100 tablets (each tablet contains 60mg of the active ingredient and has an area of ​​2cm×2cm).

Claims

1. A linezolid derivative, characterized in that, Its general structural formula I is: ； Where R1 is or ; R2 is , , , , , , , , , , , , , , and Any one of them.

2. The linezolid-containing derivative according to claim 1, characterized in that, The linezolid derivative is one of the following compounds: (S)-N-(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinylphenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl]-1H-1,2,4-triazol-3-carboxamide; 1-(4-((((S)-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(1-(1-(methanesulfonyl)pyrrolidine-3-yl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(((1-methyl-1H-pyrazol-3-yl)methyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(2-(thiophen-2-yl)ethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(4-(trifluoromethyl)cyclohexyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(1-Cyclopropylpiperidin-4-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(1-(1-(methanesulfonyl)piperidin-4-yl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(pyrimidin-2-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(pyridin-4-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(2-(pyridin-3-yl)ethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(3,5-difluorobenzyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-1H-1,2,4-triazol-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-N-(thiophen-3-ylmethyl)-1H-1,2,4-triazol-3-carboxamide; (S)-N-(5-cyanothiophene-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; 1-(4-((((S)-3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(1-(1-(methylsulfonyl)pyrrolidine-3-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-N-(2-Cyclohexylethyl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-N-(1,1-dioxotetrahydro-2H-thiopyran-4-yl)-1-(4-(((3-(3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(((1-methyl-1H-pyrazol-4-yl)methyl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(2-(thiophen-2-yl)ethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-N-(5-cyclopropyl-1H-pyrazol-3-yl)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidine-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-N-(1-(1-(methylsulfonyl)piperidin-4-yl)-6-oxo-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyrimidin-2-ylmethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(pyridin-4-ylmethyl)-1,6-dihydropyridazine-3-carboxamide; (S)-1-(4-(((3-(3-fluoro-4-morpholinophenyl)-2-oxooxazolidin-5-yl)methyl)carbamoyl)phenyl)-4-methyl-6-oxo-N-(thiophen-3-ylmethyl)-1,6-dihydropyridazine-3-carboxamide.

3. A method for preparing a linezolid derivative according to any one of claims 1-2, characterized in that, R1 is At that time, the linezolid-containing derivative was prepared according to route 1; R1 is At the same time, the linezolid-containing derivative was prepared according to route 2; Route 1 includes the following steps: mixing 4-aminobenzoic acid with sodium nitrite in a solvent to carry out a diazotization reaction to obtain a diazonium salt; The diazonium salt was subjected to a cyclization and substitution reaction with an isocyanoacetate compound and sodium acetate to obtain intermediate X2. The intermediate X2 was dissolved in an organic solvent and subjected to an amide condensation reaction with (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one in the presence of a condensing agent and a base to obtain intermediate X3. The intermediate X3 was hydrolyzed under alkaline conditions and then acidified to obtain intermediate X4. The intermediate X4 was dissolved in an organic solvent and then reacted with an amine compound in the presence of a condensing agent and a base to complete the preparation. In Route 1, the types of amine compounds are 4-aminothiophene-2-onitrile, 1-(methanesulfonyl)pyrrolidine-3-amine, 1,1-dioxotetrahydro-2H-thiopyran-4-amine, (1-methyl-1H-pyrazol-3-yl)methylamine, 2-(thiophene-2-yl)ethylamine, 4-(trifluoromethyl)cyclohexylamine, 5-cyclopropyl-1H-pyrazol-3-amine, 1-cyclopropylpiperidine-4-amine, 1-(methanesulfonyl)piperidine-4-amine, pyrimidin-2-ylmethylamine, pyridin-4-ylmethylamine, 2-(pyridin-3-yl)ethylamine, 3,5-difluorobenzylamine, or thiophene-3-ylmethylamine; Route 2 includes the following steps: mixing 4-aminobenzoic acid with sodium nitrite in a solvent to carry out a diazotization reaction to obtain a diazonium salt; The diazonium salt was coupled with ethyl acetoacetate and ammonium acetate to obtain intermediate Y2; The intermediate Y2 was dissolved in an organic solvent and, in the presence of a condensing agent and a base, was subjected to an amide condensation reaction with (S)-5-(aminomethyl)-3-(3-fluoro-4-morpholinophenyl)oxazolidin-2-one to obtain intermediate Y3. The intermediate Y3 was reacted with ethyl (triphenylphosphine) in an organic solvent by a Wittig reaction to obtain intermediate Y4; The intermediate Y4 was hydrolyzed under alkaline conditions and then acidified to obtain the key intermediate Y5. The intermediate Y5 was dissolved in an organic solvent and then reacted with an amine compound in the presence of a condensing agent and a base to complete the preparation. In Route 2, the types of amine compounds are 4-aminothiophene-2-onitrile, 1-(methanesulfonyl)pyrrolidine-3-amine, 2-cyclohexylethylamine, 1,1-dioxotetrahydro-2H-thiopyran-4-amine, (1-methyl-1H-pyrazol-4-yl)methylamine, 2-(thiophene-2-yl)ethylamine, 4-(trifluoromethyl)cyclohexylamine, 5-cyclopropyl-1H-pyrazol-3-amine, 1-(methanesulfonyl)piperidin-4-amine, pyrimidin-2-ylmethylamine, pyridin-4-ylmethylamine, or thiophene-3-ylmethylamine.

4. A pharmaceutical composition, characterized in that, Its active ingredients include the linezolid derivative as described in any one of claims 1-2.

5. The pharmaceutical composition according to claim 4, characterized in that, The pharmaceutical composition also contains pharmaceutically acceptable excipients.

6. The pharmaceutical composition according to claim 4, characterized in that, The dosage form of the pharmaceutical composition is tablets, capsules, ointments, aerosols, suppositories, drop pills, topical liniments, injections, or films.

7. Use of a linezolid derivative according to any one of claims 1-2 or a pharmaceutical composition according to any one of claims 4-6 in the preparation of a medicament for treating and / or preventing bacterial infectious diseases.

8. The application according to claim 7, characterized in that, The bacteria that cause the aforementioned bacterial infectious diseases are at least one of Staphylococcus aureus and Staphylococcus epidermidis.

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