Pleuromutilin derivatives and preparation methods thereof

Abstract

The present invention discloses a pleuromutilin derivative, a preparation method thereof, and an application thereof. A pleuromutilin derivative of the present invention has a structural chemical formula as shown in formula (I): #imgabs0# and a chemical name of (3aR, 4R, 5R, 7S, 8S, 9R, 9aS, 12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propoxycyclopenta[8]annulene-5-yl 2-(4-((E)-2-((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazine-1-yl)acetate (Compound 9a). Compound 9a, synthesized using N-Boc-piperazine as a starting material, has excellent antibacterial activity against Staphylococcus aureus. According to a CFU test, Compound 9a has better activity than pleuromutilin.

Description

Technical Field

[0001] The present invention relates to the technical field of drug preparation, in particular to a pleuromutilin derivative and a preparation method thereof. Background Art

[0002] In recent years, natural products have been used extensively to combat bacterial and fungal infections. Antibiotics are primarily categorized into nine classes: β-lactams, tetracyclines, oxadiazolidines, glycopeptides, aminoglycosides, lincosamides, sulfonamides, oxazolidinones, and fluoroquinolones. The first six are derivatives of natural products, while only the last three are entirely synthesized through chemical design. Pleuromutilin is a diterpenoid compound with a tricyclic backbone produced by submerged culture of the higher basidiomycete fungi Pleurotus mutilis and Pleurotus passeckerianus. Pleuromutilin antibacterial drugs achieve their antibacterial activity by selectively inhibiting protein synthesis. This mechanism differs from the antibacterial mechanism of other antibiotics that inhibit protein synthesis, as it involves a unique binding mechanism to the prokaryotic ribosome. The tricyclic core of this class of antibacterial drugs is located in the center of the peptidyl transferase enzyme in the 50S large subunit of the ribosomal ribosomal unit. The tricyclic core protrudes over the ribosomal P site, and the C-14 side chain penetrates deep into the internal cavity of the enzyme. They interfere with bacterial protein synthesis through a triple process: these compounds bind to the 23S rRNA of the 50S large subunit, inhibiting peptide transfer, preventing interactions at the P site, and suppressing normal 50S large subunit formation. Consequently, bacterial protein synthesis is disrupted, leading to bacterial death. Clinical use of pleuromutilins has shown a very slow development of target-specific resistance in bacteria, and no cross-resistance has been observed to mupirocin, β-lactams, macrolide antibiotics, or quinolones, highlighting the significant advantages of this class of molecules.

[0003] However, due to their poor water solubility and short half-life, pleuromutilins, despite their good antibacterial activity, are difficult to directly use in drug development. Consequently, attempts have been made to modify their structure, such as modifying the parent nucleus of pleuromutilin compounds based on their metabolic sites, in an attempt to obtain derivatives with improved solubility, longer half-lives, and higher antibacterial activity. Research has revealed that the carbonyl group on the five-membered ring and the hydroxyl group on C-11 in the molecular structure are essential functional groups for the basic activity of this class of antibiotics. Consequently, most research, both domestically and internationally, has focused on chemically modifying C-14. In recent years, four pleuromutilin derivatives have been approved for clinical use. These studies have provided new approaches to modifying pleuromutilins, including introducing five-membered rings (thiazole, thiadiazole, and triazole), six-membered rings (piperazine, pyridine, pyrimidine, tetrahydropyrone), and carbamates into the C-14 side chain, with the goal of synthesizing compounds with high antibacterial activity. Summary of the Invention

[0004] The object of the present invention is to provide a pleuromutilin derivative and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above object, the invention provides the following technical solution: a pleuromutilin derivative having the formula:

[0006]

[0007] The preparation method of the pleuromutilin derivative specifically comprises the following steps:

[0008] Step 1: Under ice bath, 2.39 ml, 17.17 mmol of triethylamine was slowly added to 150 ml of acetonitrile solution of 5 g, 13.21 mmol of pleuromutilin and 2.77 g, 14.53 mmol of p-toluenesulfonyl chloride, and the mixture was stirred for 6 hours. The solvent was removed by rotary evaporation, and the residue was extracted with dichloromethane (DCM). The organic phase was collected and dried over anhydrous sodium sulfate. After filtration, the filtrate was collected and concentrated. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 3:1 to 2:1 to obtain (3aR, 4R, 5R, 7S, 8S, 9R, 9aS, 12R)-8-hydroxy-4, 7, 9, 12-tetramethyl-3-oxo-7-vinyldecahydro-4, 9a-propoxycyclopenta[8]annulene-5-yl 2-(toluenesulfonyloxy)acetate (Compound 2) as a white solid;

[0009] Step 2: 0.82 ml, 5.91 mmol of triethylamine was slowly added to a mixture of 1 g, 5.37 mmol of N-Boc-piperazine and 1.14 g, 5.37 mmol of 2-bromo-4'-methylacetophenone in 30-50 ml of acetonitrile, and the mixture was stirred at room temperature for 3-6 hours. The reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain tert-butyl 4-(2-oxo-2-(p-tolyl)ethyl)piperazine-1-carboxylate (Compound 5a) as a yellow solid;

[0010] Step 3: 0.15 g, 6.28 mmol of lithium hydroxide was slowly added to 1 g, 3.14 mmol of compound 5a in 20-40 ml of methanol, and the mixture was stirred at room temperature for 1 hour, and then 0.52 g, 6.28 mmol of o-methylhydroxylamine hydrochloride in 10-15 ml of methanol was slowly added dropwise, and the mixture was stirred at room temperature for 2-4 hours; the solvent was removed by rotary evaporation, and the mixture after rotary evaporation was extracted with DCM. The organic phases were combined and dried over Na2SO4; the crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain (E)-4-(2-(hydroxyimino)-2-(p-tolyl)ethyl)piperazine-1-carboxylic acid tert-butyl ester (compound 6a) as a light yellow solid;

[0011] Step 4: 0.49 g, 2.83 mmol of 2-naphthoic acid, 0.52 g, 4.24 mmol of 4-dimethylaminopyridine (DMAP) and 0.81 g, 4.24 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) were dissolved in DCM and stirred at room temperature for 1.5 hours. Then, 0.5 g, 1.41 mmol of compound 6a were slowly added, and the mixture was stirred at room temperature for 5 hours; the reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4; the crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain (E)-4-(2-(((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazine-1-carboxylic acid tert-butyl ester (compound 7a) as a yellow solid;

[0012] Step 5: Add 0.25 g, 0.49 mmol of compound 7a to a solution of DCM: trifluoroacetic acid = 4:1, stir at room temperature for 1 hour, remove the solvent by rotary evaporation, extract the mixture after rotary evaporation with DCM, combine the organic phases and dry with Na2SO4 to obtain compound 8a, add 0.20 g, 0.49 mmol of compound 8a and 0.1 g, 0.74 mmol of anhydrous potassium carbonate to a solution of 0.24 g, 0.49 mmol of compound 3 in 50 ml of acetonitrile, and stir at 70°C for 2 hours. The solvent was removed by rotary evaporation, and the mixture after rotary evaporation was extracted with DCM. The organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 10:1 to 5:1 to give (3aR,4R,5R,7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propoxycyclopenta[8]annulene-5-yl 2-(4-((E)-2-((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazin-1-yl)acetate (Compound 9a) as a light yellow solid.

[0013] Preferably, the pleuromutilin derivative is used to resist Staphylococcus aureus infection.

[0014] Compared with the prior art, the invention has the beneficial effect that the prepared pleuromutilin derivative has a better effect of resisting Staphylococcus aureus infection. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the CFU test of compounds 9a, 9b, 9c, and 9d of the present invention at different concentrations against Staphylococcus aureus;

[0016] Figure 2 Schematic diagram of the CFU test of compounds 9e, 9f, 9g, and 9h of the present invention at different concentrations against Staphylococcus aureus;

[0017] Figure 3 Schematic diagram of the CFU test of compounds 9i and 9j of the present invention at different concentrations against Staphylococcus aureus;

[0018] Figure 4 Schematic diagram of the reaction synthesis route of the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] A pleuromutilin derivative having the formula:

[0021]

[0022]

[0023] The preparation method of the pleuromutilin derivative specifically comprises the following steps:

[0024] Step 1: Under ice bath, 2.39 ml, 17.17 mmol of triethylamine was slowly added to 150 ml of acetonitrile solution of 5 g, 13.21 mmol of pleuromutilin and 2.77 g, 14.53 mmol of p-toluenesulfonyl chloride, and the mixture was stirred for 6 hours. The solvent was removed by rotary evaporation, and the residue was extracted with dichloromethane (DCM). The organic phase was collected and dried over anhydrous sodium sulfate. After filtration, the filtrate was collected and concentrated. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 3:1 to 2:1 to obtain (3aR, 4R, 5R, 7S, 8S, 9R, 9aS, 12R)-8-hydroxy-4, 7, 9, 12-tetramethyl-3-oxo-7-vinyldecahydro-4, 9a-propoxycyclopenta[8]annulene-5-yl 2-(toluenesulfonyloxy)acetate (Compound 2) as a white solid;

[0025] Step 2: 0.82 ml, 5.91 mmol of triethylamine was slowly added to a mixture of 1 g, 5.37 mmol of N-Boc-piperazine and 1.14 g, 5.37 mmol of 2-bromo-4'-methylacetophenone in 30-50 ml of acetonitrile, and the mixture was stirred at room temperature for 3-6 hours. The reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain tert-butyl 4-(2-oxo-2-(p-tolyl)ethyl)piperazine-1-carboxylate (Compound 5a) as a yellow solid;

[0026] Step 3: 0.15 g, 6.28 mmol of lithium hydroxide was slowly added to 1 g, 3.14 mmol of compound 5a in 20-40 ml of methanol, and the mixture was stirred at room temperature for 1 hour, and then 0.52 g, 6.28 mmol of o-methylhydroxylamine hydrochloride in 10-15 ml of methanol was slowly added dropwise, and the mixture was stirred at room temperature for 2-4 hours; the solvent was removed by rotary evaporation, and the mixture after rotary evaporation was extracted with DCM. The organic phases were combined and dried over Na2SO4; the crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain (E)-4-(2-(hydroxyimino)-2-(p-tolyl)ethyl)piperazine-1-carboxylic acid tert-butyl ester (compound 6a) as a light yellow solid;

[0027] Step 4: 0.49 g, 2.83 mmol of 2-naphthoic acid, 0.52 g, 4.24 mmol of 4-dimethylaminopyridine (DMAP) and 0.81 g, 4.24 mmol of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) were dissolved in DCM and stirred at room temperature for 1.5 hours. Then, 0.5 g, 1.41 mmol of compound 6a were slowly added, and the mixture was stirred at room temperature for 5 hours; the reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4; the crude mixture was purified by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain (E)-4-(2-(((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazine-1-carboxylic acid tert-butyl ester (compound 7a) as a yellow solid;

[0028] Step 5: Add 0.25 g, 0.49 mmol of compound 7a to a solution of DCM: trifluoroacetic acid = 4:1, stir at room temperature for 1 hour, remove the solvent by rotary evaporation, extract the mixture after rotary evaporation with DCM, combine the organic phases and dry with Na2SO4 to obtain compound 8a, add 0.20 g, 0.49 mmol of compound 8a and 0.1 g, 0.74 mmol of anhydrous potassium carbonate to a solution of 0.24 g, 0.49 mmol of compound 3 in 50 ml of acetonitrile, and stir at 70°C for 2 hours. The solvent was removed by rotary evaporation, and the mixture after rotary evaporation was extracted with DCM. The organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 10:1 to 5:1 to give (3aR,4R,5R,7S,8S,9R,9aS,12R)-8-hydroxy-4,7,9,12-tetramethyl-3-oxo-7-vinyldecahydro-4,9a-propoxycyclopenta[8]annulene-5-yl 2-(4-((E)-2-((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazin-1-yl)acetate (Compound 9a) as a light yellow solid.

[0029] Example 1. Synthesis and antibacterial activity study of compound 9a.

[0030] 1. Synthesis of compound 2.

[0031] The reaction process is the same as step 1, with a yield of 93.4%. 1H NMR(500MHz,Chloroform-d)δ7.83–7.79(m,2H),7.37–7.33(m,2H),6.40(dd,J=17.4,11.0Hz,1H),5.76(d,J=8.6Hz,1H),5.34–5. 30(m,1H),5.19(dd,J=17.4,1.6Hz,1H),4.48(s,2H),3.35(dd,J=10.5,6.5Hz,1H),2.45(s,3H),2.30–2.14(m,3H),2.10–1.99(m,2 H),1.79–1.72(m,1H),1.64(ddd,J=12.3,10.7,8.3,4.9Hz,2H),1.53(d,J=10.4Hz,1H),1.47(d,J=2.9Hz,1H),1.40(s,3H),1.37–1 .31(m,1H),1.26(d,J=5.9Hz,1H),1.24–1.21(m,1H),1.15(s,3H),1.13–1.08(m,1H),0.88(d,J=7.0Hz,3H),0.62(d,J=7.1Hz,3H).

[0032] 2. Synthesis of compound 5a.

[0033] The reaction process is the same as step 2, with a yield of 87.5%. 1 H NMR(500MHz,Chloroform-d)δ7.87(d,J=8.2Hz,2H),7.25(d,J=8.0Hz,2H),3.86(s,2 H), 3.52 (t, J = 5.1Hz, 4H), 2.61 (t, J = 5.0Hz, 4H), 2.40 (d, J = 3.8Hz, 3H), 1.47 (s, 9H).

[0034] 3. Synthesis of compound 6a.

[0035] The reaction process is the same as step 3, with a yield of 38.8%. 1 H NMR(500MHz,Chloroform-d)δ7.89(dd,J=8.2,1.9Hz,2H),7.25(dd,J=8.2,2.1Hz,2H),3.80(d, J=1.7Hz,2H),3.50(t,J=5.0Hz,4H),2.55(t,J=5.1Hz,4H),2.41(d,J=2.1Hz,3H),1.46(s,9H).

[0036] 4. Synthesis of compound 7a.

[0037] The reaction process is the same as step 4, with a yield of 56.4%. 1 H NMR(500MHz,Chloroform-d)δ8.60(d,J=1.6Hz,1H),8.03(dd,J=8.5,1.7Hz,1H),7.9 1(d,J=8.0Hz,1H),7.86(d,J=8.6Hz,1H),7.83(d,J=8.1Hz,1H),7.81–7.77(m,2H),7 .54(ddd,J=8.2,6.8,1.4Hz,1H),7.49(ddd,J=8.0,6.8,1.3Hz,1H),7.15(d,J=8.1Hz ,2H),3.81(s,2H),3.30(q,J=8.7,6.8Hz,4H),2.46(s,4H),2.31(s,3H),1.34(s,9H).

[0038] 5. Synthesis of compound 9a.

[0039] The reaction process is the same as step 5, with a yield of 72.5%. 1H NMR(500MHz,Chloroform-d)δ8.61(s,1H),8.04(d,J=8.6Hz,1H),7.93(d,J=8.1Hz,1H),7.86(d ,J=8.8Hz,1H),7.84(d,J=7.8Hz,1H),7.80(d,J=7.9Hz,2H),7.55(t,J=7.5Hz,1H),7.51(t,J=7 .5Hz,1H),7.14(d,J=8.0Hz,2H),6.37(ddd,J=31.8,17.4,10.9Hz,2H),5.68(d,J=8.4Hz,1H),5 .27(d,J=11.1Hz,1H),5.09(d,J=17.2Hz,1H),3.81(s,2H),3.60–3.48(m,1H),3.28(dt,J=15.8 ,7.7Hz,2H),3.07(d,J=17.1Hz,1H),2.92(d,J=17.1Hz,1H),2.62(s,4H),2.51(s,1H),2.42(s, 1H),2.32(s,3H),2.24(t,J=7.0Hz,1H),2.16(d,J=8.7Hz,1H),2.12(d,J=9.5Hz,1H),2.03(d,J =3.5Hz,1H),1.70–1.64(m,2H),1.57(s,1H),1.55(s,1H),1.38(s,2H),1.34(s,3H),1.26(d,J= 4.9Hz,1H),1.24(s,1H),1.11(s,1H),1.06(s,3H),0.78(d,J=7.0Hz,3H),0.61(d,J=7.0Hz,3H).

[0040] 6. Anti-Staphylococcus aureus activity of compound 9a.

[0041] CFU analysis: The antibacterial activity of each single substance extract against Staphylococcus aureus and Escherichia coli was determined by the agar plate CFU counting method. The resulting colonies were counted to determine the CFU and growth inhibitory activity of the drug. The bacterial suspension was incubated with different concentrations of the extract for 3 hours. Subsequently, 30 μl of 10-fold serial dilutions of bacteria at different concentrations were dropped onto TSB and LB agar plates and incubated at 37°C for 24 hours, with three replicates per group. After incubation at 37°C for 24 hours, the colonies were counted. Representative images of BHI agar plates were acquired with an iPhone 12. Data from three parallel plates were obtained.

[0042] Example 2. Synthesis of compound 9b and study of its antibacterial activity.

[0043] 1. Synthesis of compound 2.

[0044] The reaction process and results are the same as above.

[0045] 2. Synthesis of compound 5b.

[0046] The reaction process is the same as step 2, with a yield of 76.5%. 1 H NMR(500MHz,Chloroform-d)δ8.01–7.96(m,2H),7.04(t,J=8.6Hz,2H),4.02(q,J =7.1Hz,2H),3.65(dt,J=13.1,3.9Hz,1H),3.58(d,J=16.4Hz,1H),3.06(ddd,J=1 3.2,9.9,3.1Hz,1H),2.80(d,J=36.9Hz,1H),2.69(dt,J=11.5,3.7Hz,1H),2.57( tt,J=7.1,3.3Hz,1H),2.37(d,J=22.0Hz,1H),1.37(s,9H),1.01(d,J=6.4Hz,3H).

[0047] 3. Synthesis of compound 6b.

[0048] The reaction process is the same as step 3, with a yield of 33.4%. 1 H NMR(500MHz,Chloroform-d)δ7.60–7.56(m,2H),6.98(t,J=8.6Hz,2H),3.97(d,J=14.5Hz,1H),3.78–3.69(m,1H),3.65(dt,J=13.4,4.1Hz, 1H),3.57(t,J=13.2Hz,2H),3.11(s,1H),2.79(dt,J=11.8,3.9Hz,1H),2.49–2.42(m,1H),2.27(s,1H),1.39(s,9H),1.12(d,J=6.4Hz,3H).

[0049] 4. Synthesis of compound 7b.

[0050] The reaction process is the same as step 4, with a yield of 68.9%. 1H NMR(500MHz,Chloroform-d)δ8.61(d,J=1.7Hz,1H),8.03(dd,J=8.5,1.7Hz,1H),7.94–7.91(m,2H),7.91(d,J= 2.2Hz,1H),7.88(d,J=8.6Hz,1H),7.85(d,J=8.1Hz,1H),7.58–7.54(m,1H),7.51(td,J=7.5,6.7,1.4Hz,1H),7 .04(t,J=8.6Hz,2H),3.99(d,J=13.3Hz,1H),3.79(d,J=13.3Hz,1H),3.53(dt,J=13.6,4.2Hz,1H),2.94(s,1H) ,2.68(d,J=11.9Hz,1H),2.44(tt,J=9.3,4.2Hz,1H),2.22(s,1H),1.63(s,2H),1.35(s,9H),1.12–1.09(m,3H).

[0051] 5. Synthesis of compound 9b.

[0052] The reaction process is the same as step 5, with a yield of 74.1%. 1H NMR(500MHz,Chloroform-d)δ8.62(d,J=1.7Hz,1H),8.04(dt,J=8.6,1.5Hz,1H),7.96(d,J=2.0Hz,1H),7.94(d,J=3.5Hz ,1H),7.93(s,1H),7.88(d,J=8.6Hz,1H),7.86(d,J=8.0Hz,1H),7.57(ddd,J=8.2,6.8,1.4Hz,1H),7.53(ddd,J=8.0,6.8 ,1.4Hz,1H),7.03(t,J=8.6Hz,2H),6.46–6.31(m,2H),5.70(dd,J=8.5,2.1Hz,1H),5.31–5.26(m,1H),5.12(dd,J=6.8,1 .6Hz,1H),3.97(d,J=13.0Hz,1H),3.83(dd,J=13.1,2.3Hz,1H),3.61–3.50(m,1H),3.29(dq,J=16.1,8.2,7.4Hz,2H),3.0 9–3.01(m,1H),2.91(d,J=16.2Hz,1H),2.72(d,J=12.2Hz,1H),2.59(s,1H),2.45(d,J=10.6Hz,1H),2.26(dd,J=8.5,5.3 Hz,1H),2.20–2.17(m,1H),2.16(d,J=6.8Hz,1H),2.13(d,J=2.6Hz,1H),2.04(d,J=2.5Hz,1H),2.00(d,J=3.8Hz,1H),1.9 6(d,J=8.6Hz,1H),1.71–1.68(m,1H),1.57(d,J=2.0Hz,1H),1.56–1.55(m,1H),1.49(d,J=3.4Hz,1H),1.39(s,2H),1.35 (d,J=3.5Hz,3H),1.28(s,1H),1.19(t,J=7.7Hz,3H),1.12(s,2H),1.11(s,1H),1.07(s,3H),0.82(dd,J=7.1,4.5Hz,3H).

[0053] 6. Anti-Staphylococcus aureus activity of compound 9b.

[0054] The test process is the same as above, and the results are shown in Figure 1 .

[0055] Example 3. Synthesis of compound 9c and study of its antibacterial activity.

[0056] 1. Synthesis of compound 2.

[0057] The reaction process and results are the same as above.

[0058] 2. Synthesis of compound 5a.

[0059] The reaction process and results are the same as above.

[0060] 3. Synthesis of compound 9c.

[0061] The reaction process is the same as step 5, with a yield of 74.3%. 1 H NMR(500MHz,Chloroform-d)δ7.81(d,J=8.0Hz,2H),7.17(d,J=7.9Hz,2H),6.43(ddd,J=17.0,11.0,5.9Hz,1H),5.71(d,J=8.3Hz,1H),5.24(dd,J=10.9,1.6 Hz,1H),5.16–5.09(m,1H),4.08–3.93(m,1H),3.73(s,2H),3.29(d,J=6.6Hz, 1H),3.11(d,J=17.1Hz,1H),2.97(d,J=17.1Hz,1H),2.53(d,J=8.7Hz,3H),2.3 3(s,3H),2.27(q,J=6.8Hz,1H),2.15(dq,J=12.8,9.4,8.8Hz,2H),2.05–1.99 (m,2H),1.97(s,1H),1.70(dt,J=14.6,3.1Hz,1H),1.58(ddt,J=10.9,8.7,4.4 Hz,3H),1.48(dd,J=13.2,3.7Hz,1H),1.37(s,3H),1.30–1.25(m,1H),1.25–1. 19(m,2H),1.09(d,J=2.4Hz,3H),0.80(d,J=7.1Hz,3H),0.65(d,J=7.1Hz,3H).

[0062] 4. Anti-Staphylococcus aureus activity of compound 9c.

[0063] The test process is the same as above, and the results are shown in Figure 1 .

[0064] Example 4. Synthesis and antibacterial activity study of compound 9d.

[0065] 1. Synthesis of compound 2.

[0066] The reaction process and results are the same as above.

[0067] 2. Synthesis of compound 5a.

[0068] The reaction process and results are the same as above.

[0069] 3. Synthesis of compound 6d.

[0070] The reaction process is the same as step 3, with a yield of 36.8%. 1 H NMR(500MHz,Chloroform-d)δ7.73–7.70(m,2H),7.14(d,J=8.0Hz,2H),3.61(s,2H), 3.35(t,J=5.3Hz,4H),2.43(t,J=5.0Hz,4H),2.35(s,3H),1.46(s,9H),1.34(s,9H).

[0071] 4. Synthesis of compound 9d.

[0072] The reaction process is the same as step 5, with a yield of 77.3%. 1 H NMR(500MHz,Chloroform-d)δ7.63(d,J=8.3Hz,2H),7.14(d,J=8.1Hz,2H),6.43–6.39(m,1H),5.72(d,J=8.5Hz,1H),5.35(dd,J=4.1,1.5Hz,1H),5.31(t, J=2.3Hz,1H),5.20(t,J=1.4Hz,1H),3.66(d,J=10.5Hz,1H),3.58(d,J=10.4 Hz,1H),3.36(d,J=4.0Hz,4H),3.17–3.13(m,1H),3.02–2.98(m,1H),2.56(s, 4H),2.47(s,3H),2.27–2.26(m,1H),2.24(d,J=3.6Hz,1H),2.20(d,J=3.0Hz ,1H),2.11(d,J=2.8Hz,2H),2.09(d,J=3.0Hz,1H),2.05(d,J=8.2Hz,1H),1.7 9–1.75(m,3H),1.66(s,1H),1.64(d,J=2.0Hz,1H),1.55–1.53(m,1H),1.43(s ,3H),1.28(s,9H),1.15(s,3H),0.88(d,J=3.8Hz,3H),0.75(d,J=7.0Hz,3H).

[0073] 5. Anti-Staphylococcus aureus activity of compound 9d.

[0074] The test process is the same as above, and the results are shown in Figure 1 .

[0075] Example 5. Synthesis and antibacterial activity study of compound 9e.

[0076] 1. Synthesis of compound 2.

[0077] The reaction process and results are the same as above.

[0078] 2. Synthesis of compound 5a.

[0079] The reaction process and results are the same as above.

[0080] 3. Synthesis of compound 6e.

[0081] The reaction process is the same as step 3, with a yield of 38.8%. 1 H NMR(500MHz,Chloroform-d)δ7.89(dd,J=8.2,1.9Hz,2H),7.25(dd,J=8.2,2.1Hz,2H),3.80(d, J=1.7Hz,2H),3.50(t,J=5.0Hz,4H),2.55(t,J=5.1Hz,4H),2.41(d,J=2.1Hz,3H),1.46(s,9H).

[0082] 4. Synthesis of compound 9e.

[0083] The reaction process is the same as step 5, yield: 68.6%. NMR(500MHz,Chloroform-d)δ7.45(d,J=7.9Hz,2H),7.10(d,J=7.8Hz,2H),6.44 (ddd,J=17.1,11.1,6.0Hz,1H),5.71(dd,J=8.6,4.0Hz,1H),5.29–5.24(m,1H), 5.12(d,J=17.3Hz,1H),3.70(s,2H),3.29(d,J=7.5Hz,4H),3.10(dd,J=17.1,10 .5Hz,1H),2.97(t,J=16.8Hz,1H),2.66–2.53(m,4H),2.49(d,J=8.4Hz,3H),2.2 9(s,1H),2.24–2.15(m,1H),2.11(dd,J=19.4,9.3Hz,1H),2.04–1.93(m,2H),1. 70(dd,J=14.6,3.4Hz,1H),1.60(t,J=6.7Hz,1H),1.58–1.53(m,1H),1.49(td,J =13.8,3.5Hz,1H),1.42(d,J=17.9Hz,1H),1.37(s,3H),1.32–1.25(m,1H),1.22 (d,J=8.5Hz,1H),1.18(s,3H),1.09(s,3H),0.81(s,3H),0.64(d,J=6.9Hz,3H).

[0084] 5. Anti-Staphylococcus aureus activity of compound 9e.

[0085] The test process is the same as above, and the results are shown in Figure 2 .

[0086] Example 6. Synthesis and antibacterial activity study of compound 9f.

[0087] 1. Synthesis of compound 2.

[0088] The reaction process and results are the same as above.

[0089] 2. Synthesis of compound 5f.

[0090] The reaction process is the same as step 2, with a yield of 86.3%. 1H NMR(500MHz,Chloroform-d)δ7.92–7.89(m,2H),7.25(d,J=8.0Hz,2H),4.12(q,J=7.1Hz,2H),3.73(dt,J=23.7,10.5Hz,2H),3.15(ddd,J=13.4, 10.0,3.1Hz,1H),2.81(dt,J=11.5,3.7Hz,1H),2.67(t,J=7.2Hz,1H),2. 45(s,1H),2.41(s,3H),2.04(s,1H),1.46(s,9H),1.09(d,J=6.4Hz,3H).

[0091] 3. Synthesis of compound 9f.

[0092] The reaction process is the same as step 5, with a yield of 68.9%. 1H NMR(500MHz,Chloroform-d)δ7.44–7.37(m,2H),7.11(dd,J=8.3,2.3Hz,2H),6.43(ddd,J=17.4,10 .9,3.3Hz,1H),5.73–5.67(m,1H),5.26(dd,J=11.0,4.9Hz,1H),5.15–5.08(m,1H),3.41(t,J=5.3H z,1H),3.32–3.20(m,2H),3.17–3.06(m,1H),3.05–2.95(m,1H),2.94–2.77(m,1H),2.76–2.62(m,1 H),2.54(dd,J=28.8,10.8Hz,1H),2.38(ddd,J=39.3,11.3,4.1Hz,1H),2.29(s,3H),2.28–2.24(m, 1H),2.21(dd,J=11.3,3.2Hz,1H),2.19–2.13(m,2H),2.13–2.07(m,1H),2.04–1.96(m,2H),1.70(d q,J=14.5,2.8Hz,1H),1.58(dt,J=13.4,10.0Hz,3H),1.49(d,J=3.7Hz,1H),1.43(s,1H),1.42–1.3 8(m,1H),1.36(t,J=2.3Hz,3H),1.35(s,1H),1.34(s,1H),1.30(d,J=2.9Hz,1H),1.27(d,J=4.4Hz, 1H),1.23(dd,J=8.4,3.8Hz,3H),1.10–1.07(m,3H),0.81(dd,J=4.2,2.6Hz,3H),0.65–0.60(m,3H).

[0093] 4. Anti-Staphylococcus aureus activity of compound 9f.

[0094] The test process is the same as above, and the results are shown in Figure 2 .

[0095] Example 7. Synthesis of compound 9g and study of its antibacterial activity.

[0096] 1. Synthesis of compound 2.

[0097] The reaction process and results are the same as above.

[0098] 2. Synthesis of compound 9g.

[0099] The reaction process is the same as step 5, with a yield of 74.3%. 1H NMR(500MHz,Chloroform-d)δ7.81(d,J=8.0Hz,2H),7.17(d,J=7.9Hz,2H),6.43(ddd,J=17.0,11.0,5.9Hz,1H),5.71(d,J=8.3Hz,1H),5.24(dd,J=10.9,1.6 Hz,1H),5.16–5.09(m,1H),4.08–3.93(m,1H),3.73(s,2H),3.29(d,J=6.6Hz, 1H),3.11(d,J=17.1Hz,1H),2.97(d,J=17.1Hz,1H),2.53(d,J=8.7Hz,3H),2.3 3(s,3H),2.27(q,J=6.8Hz,1H),2.15(dq,J=12.8,9.4,8.8Hz,2H),2.05–1.99 (m,2H),1.97(s,1H),1.70(dt,J=14.6,3.1Hz,1H),1.58(ddt,J=10.9,8.7,4.4 Hz,3H),1.48(dd,J=13.2,3.7Hz,1H),1.37(s,3H),1.30–1.25(m,1H),1.25–1. 19(m,2H),1.09(d,J=2.4Hz,3H),0.80(d,J=7.1Hz,3H),0.65(d,J=7.1Hz,3H).

[0100] 3. Anti-Staphylococcus aureus activity of compound 9g.

[0101] The test process is the same as above, and the results are shown in Figure 2 .

[0102] Example 8. Synthesis and antibacterial activity study of compound 9h.

[0103] 1. Synthesis of compound 2.

[0104] The reaction process and results are the same as above.

[0105] 2. Synthesis of compound 5h.

[0106] The reaction process was the same as in Step 2. Yield: 87.5%. 1H NMR (500 MHz, Chloroform-d) δ 8.01 (d, J = 3.0 Hz, 1H), 7.72 (d, J = 3.1 Hz, 1H), 4.11 (s, 2H), 3.53 (d, J = 5.1 Hz, 4H), 2.63 (t, J = 5.1 Hz, 4H), 1.47 (s, 9H).

[0107] 3. Synthesis of compound 9h.

[0108] The reaction process is the same as step 5, yield: 52.3%. NMR(500MHz,Chloroform-d)δ7.92(d,J=4.8Hz,1H),7.67(d,J=4.6Hz,1H),5.68( m,J=10.8,1.9,0.9Hz,1H),5.10(dd,J=10.8,2.4Hz,1H),5.00(tq,J=5.7,1.5Hz,1 H), 4.96 (dd, J=11.0, 2.4Hz, 1H), 3.89 (d, J=5.5Hz, 2H), 3.46 (ddd, J=8.1, 6.2, 3. 1,1.5Hz,1H),3.36(d,J=1.0Hz,2H),2.92(d,J=6.6Hz,1H),2.70–2.67(m,4H),2.6 6–2.63(m,4H),2.35–2.26(m,2H),2.13(dd,J=12.5,5.7Hz,1H),1.80(ddd,J=12. 3,5.3,3.9Hz,1H),1.74–1.69(m,2H),1.67–1.62(m,1H),1.61–1.57(m,1H),1.57– 1.52(m,1H),1.48(ddd,J=12.0,8.0,4.9Hz,1H),1.44–1.37(m,1H),1.08(t,J=1.3 Hz,3H),1.06(t,J=1.5Hz,3H),0.97(dd,J=6.3,1.5Hz,3H),0.94(d,J=6.5Hz,3H).

[0109] 4. Anti-Staphylococcus aureus activity of compound 9h.

[0110] The test process is the same as above, and the results are shown in Figure 2 .

[0111] Example 9. Synthesis and antibacterial activity study of compound 9i.

[0112] 1. Synthesis of compound 2.

[0113] The reaction process and results are the same as above.

[0114] 2. Synthesis of compound 5h.

[0115] The reaction process and results are the same as above.

[0116] 3. Synthesis of compound 6i.

[0117] The reaction process was the same as in Step 3. Yield: 32.6%. 1H NMR (500 MHz, Chloroform-d) δ 7.80 (d, J = 3.3 Hz, 1H), 7.38 (d, J = 3.3 Hz, 1H), 3.48 (s, 2H), 3.30 (t, J = 5.1 Hz, 4H), 2.40 (t, J = 5.1 Hz, 4H), 1.30 (s, 9H).

[0118] 4. Synthesis of compound 9i.

[0119] The reaction process was the same as step 5, with a yield of 43.7%. 1H NMR (500 MHz, Chloroform-d) δ7.87 (d, J = 3.3 Hz, 1H), 7.44 (d, J = 3.3 Hz, 1H), 6.43 (dd, J = 17.4, 10.9 Hz, 1H), 5.72 (d, J = 8.5 Hz, 1H), 5.27–5.24 (m, 1H), 5.11 (dd, J = 17.4, 1.7 Hz, 1H), 4.05 ( q,J=7.2Hz,1H),3.63(s,2H),3.28(t,J=7.8Hz,2H),3.13(d,J=17.0Hz,1H),2.99(d,J=17.0 Hz,1H),2.70–2.63(m,4H),2.60(s,1H),2.52(s,1H),2.30–2.25(m,1H),2.21–2.09(m,3H), 2.03–2.01(m,1H),1.97(s,1H),1.72–1.67(m,1H),1.59(d,J=3.4Hz,1H),1.58–1.56(m,1H) ,1.48(dd,J=13.5,3.5Hz,1H),1.46–1.43(m,1H),1.41(d,J=6.2Hz,1H),1.36(s,3H),1.29( d, J = 4.2 Hz, 1H), 1.26 (dd, J = 6.9, 2.6 Hz, 1H), 1.22 (d, J = 3.9 Hz, 1H), 1.19 (s, 1H), 1.08 (s, 3H), 1.05 (d, J = 4.5 Hz, 1H), 0.80 (d, J = 6.9 Hz, 3H), 0.64 (d, J = 6.9 Hz, 3H). 5. Anti-Staphylococcus aureus activity of compound 9i.

[0120] The test process is the same as above, and the results are shown in Figure 3 .

[0121] Example 10. Synthesis and antibacterial activity study of compound 9j.

[0122] 1. Synthesis of compound 2.

[0123] The reaction process and results are the same as above.

[0124] 2. Synthesis of compound 5h.

[0125] The reaction process and results are the same as above.

[0126] 3. Synthesis of compound 6i.

[0127] The reaction process and results are the same as above.

[0128] 4. Synthesis of compound 7j.

[0129] The reaction process was the same as that in step 4. Yield: 63%. 1H NMR (500 MHz, Chloroform-d) δ 8.75 (s, 1H), 8.17–8.13 (m, 1H), 8.04 (d, J = 3.3 Hz, 1H), 7.95–7.91 (m, 2H), 7.86 (d, J = 8.3 Hz, 1H), 7.66 (d, J = 3.2 Hz, 1H), 7.58 (t, J = 7.5 Hz, 1H), 7.53 (d, J = 7.6 Hz, 1H), 4.08 (d, J = 8.3 Hz, 2H), 3.40 (t, J = 4.9 Hz, 4H), 2.72–2.64 (m, 4H), 1.38 (s, 9H).

[0130] 5. Synthesis of compound 9j.

[0131] The reaction process is the same as step 5, with a yield of 33.2%. 1H NMR(500MHz,Chloroform-d)δ8.64(s,1H),8.05(dd,J=8.6,1.7Hz,1H),7.94(d,J=8.2Hz,1H),7.90(d, J=3.2Hz,1H),7.89(d,J=8.6Hz,1H),7.86(d,J=8.1Hz,1H),7.58(ddd,J=8.1,6.8,1.4Hz,1H),7.53(dd d,J=8.2,6.8,1.3Hz,1H),7.42(d,J=3.2Hz,1H),6.48–6.36(m,2H),5.68(d,J=8.4Hz,1H),5.21(dd,J= 10.9,1.6Hz,1H),5.11–5.07(m,1H),3.27(d,J=8.3Hz,2H),3.09(d,J=15.9Hz,1H),2.94(d,J=17.5Hz, 1H),2.73(s,4H),2.28(dd,J=7.1,2.9Hz,1H),2.26–2.24(m,1H),2.18–2.15(m,1H),2.15–2.14(m,1H) ,2.13–2.09(m,1H),2.03(d,J=7.6Hz,1H),2.00(d,J=2.5Hz,1H),1.69(d,J=4.1Hz,1H),1.66(d,J=2.8 Hz,1H),1.58(d,J=3.1Hz,1H),1.51–1.48(m,1H),1.47–1.45(m,1H),1.37(d,J=2.4Hz,3H),1.34(s,3H ),1.27(dd,J=4.6,2.5Hz,1H),1.24–1.23(m,1H),1.20(s,3H),1.17(s,3H),1.11(s,1H),1.06(s,3H).

[0132] 6. Anti-Staphylococcus aureus activity of compound 9j. The test process is the same as above, and the results are shown in Figure 3 .

[0133] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A pleuromutilin derivative, characterized in that Its structural formula is: Compound 9a: Compound 9b: Compound 9e: Compound 9f: .

2. A method for preparing a pleuromutilin derivative, characterized in that: The specific steps include: Step 1: Under an ice bath, 2.39 ml, 17.17 mmol of triethylamine was slowly added to a 150 ml acetonitrile solution of 5 g, 13.21 mmol of pleuromutilin and 2.77 g, 14.53 mmol of p-toluenesulfonyl chloride. The mixture was stirred for 6 hours. The solvent was removed by rotary evaporation. The residue was extracted with dichloromethane (DCM). The organic phase was collected and dried over anhydrous sodium sulfate. The filtrate was collected and concentrated after filtration. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 3:1 to 2:1 to obtain compound 2 as a white solid: ; Step 2: 0.82 ml, 5.91 mmol of triethylamine was slowly added to a mixture of 1 g, 5.37 mmol of N-Boc-piperazine and 1.14 g, 5.37 mmol of 2-bromo-4'-methylacetophenone in 30-50 ml of acetonitrile, and the mixture was stirred at room temperature for 3-6 hours. The reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography (PE / EtOAc 10:1 to 5:1) to obtain tert-butyl 4-(2-oxo-2-(p-tolyl)ethyl)piperazine-1-carboxylate, i.e., Compound 5a, as a yellow solid. Step 3: Slowly add 0.15 g, 6.28 mmol of lithium hydroxide to a solution of 1 g, 3.14 mmol of compound 5a in 20-40 ml of methanol, and stir the mixture at room temperature for 1 hour. Then slowly add dropwise 0.52 g, 6.28 mmol of o-methylhydroxylamine hydrochloride in 10-15 ml of methanol, and stir the mixture at room temperature for 2-4 hours; remove the solvent by rotary evaporation, extract the mixture after rotary evaporation with DCM, combine the organic phases and dry with Na2SO4; purify the crude mixture by silica gel column chromatography (PE / EtOAc 10:1 to 5:1) to obtain (E)-4-(2-(hydroxyimino)-2-(p-tolyl)ethyl)piperazine-1-carboxylic acid tert-butyl ester, i.e., compound 6a, as a light yellow solid; Step 4: 0.49 g (2.83 mmol) of 2-naphthoic acid, 0.52 g (4.24 mmol) of 4-dimethylaminopyridine (DMAP), and 0.81 g (4.24 mmol) of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) were dissolved in DCM and stirred at room temperature for 1.5 hours. 0.5 g (1.41 mmol) of compound 6a was then slowly added, and the mixture was stirred at room temperature for 5 hours. The reaction mixture was extracted with DCM, and the organic phases were combined and dried over Na2SO4. The crude mixture was purified by silica gel column chromatography with PE / EtOAc 10:1 to 5:1 to obtain tert-butyl (E)-4-(2-(((2-naphthoyl)oxy)imino)-2-(p-tolyl)ethyl)piperazine-1-carboxylate, compound 7a, as a yellow solid. Step 5: Add 0.25 g, 0.49 mmol of compound 7a to a solution of DCM: trifluoroacetic acid = 4:1, stir at room temperature for 1 hour, remove the solvent by rotary evaporation, extract the mixture after rotary evaporation with DCM, combine the organic phases and dry with Na2SO4 to obtain the intermediate compound, add 0.20 g, 0.49 mmol of the intermediate compound and 0.1 g, 0.74 mmol of anhydrous potassium carbonate to a 50 ml acetonitrile solution of 0.24 g, 0.49 mmol of compound 3, stir at 70 ° C for 2 hours, remove the solvent by rotary evaporation, extract the mixture after rotary evaporation with DCM, combine the organic phases and dry with Na2SO4, and purify the crude mixture by silica gel column chromatography PE / EtOAc 10:1 to 5:1 to obtain compound 9a as a light yellow solid: 。 3. Use of the pleuromutilin derivative according to claim 1 in the preparation of a drug for resisting Staphylococcus aureus infection.

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