Method for modifying C-21 site structure of fusidic acid

Abstract

The invention discloses a method for modifying a C-21 site structure of fusidic acid, which comprises the following steps: adding fusidic acid as shown in a formula (I) and a substituted benzyl bromide reagent as shown in a formula (II) into a grinding tank, adding an alkaline reagent, adding a grinding aid and a cosolvent, adding stainless steel grinding balls with the diameter of 8mm, and grinding for 10-60 minutes at the grinding frequency of 10-30Hz. After grinding is finished, a reactant is scraped out, ethyl acetate is added to dissolve the reactant, the reactant is filtered and then washed with 10% hydrochloric acid, water and a saturated saline solution in sequence, an organic phase is dried with anhydrous sodium sulfate, concentration and column chromatography purification are conducted after filtering, and the fusidic acid C-21 esterified derivative shown in the formula (IV) is obtained. Compared with an existing chemical method, the method has the advantages that the operation is simple and convenient, the reaction condition is mild, the reaction time is short, the pollution is less, and the synthesis of the fusidic acid C-21 esterified derivative can be effectively realized.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and particularly relates to a method for synthesizing a C-21 esterified derivative of fusidic acid with the assistance of mechanical grinding. Background Art

[0002] Fusidic acid was first isolated from Fusidiosporium rhodopsinum in 1960. It is a class of tetracyclic triterpenoid compounds that has been clinically used to treat local and systemic infections caused by Staphylococci. However, fusidic acid still has disadvantages such as a narrow antibacterial spectrum, increased drug resistance, and serious adverse reactions. Its current clinical indications are relatively narrow. Therefore, researchers have attempted to structurally modify fusidic acid and study the pharmacological activity of fusidic acid C-21 esterified derivatives.

[0003] The carboxyl group at C-21 of fusidic acid is a common derivatization site, and its derivatives have a variety of pharmacological activities. Among them, the esterification product of fusidic acid at C-21, 21-fusidic acid benzyl ester, has a high anti-tumor resistance reversal activity, can sensitize KBV cells to paclitaxel, vincristine and irinotecan, and block KBV cells in the G2 / M phase to induce apoptosis; if the esterified phenyl group is replaced with a substituted benzene, the derivatives have an in vitro anti-malarial biological activity against Plasmodium falciparum NF 54 and K1 strains that is 4-49 times higher than that of fusidic acid, and have a higher selectivity index; the esterification product of fusidic acid at C-21 formed by the introduction of a nitrogen-containing heterocycle has good anti-inflammatory activity, and can exert anti-inflammatory effects by regulating inflammatory mediators, inhibiting MAPK, NF-κB and NLRP3 inflammasome signaling pathways, and can thus be used to alleviate acute lung injury.

[0004]

[0005] Currently, various chemical methods have been reported to synthesize C-21 esterified derivatives of fusidic acid, usually by reacting fusidic acid with different halides or alcohols under base catalysis (CN 109320577A, 2019.; Bioorg. Med. Chem. Lett., 2017, 27: 658-661.; Eur. J. Med. Chem., 2023, 259: 115697-115697.).

[0006] In 2019, Bi Yi et al. combined fusidic acid and benzyl bromide in K 2 CO 3 and acetone at 30 °C for 6 h to synthesize 21-fusidic acid benzyl ester (CN 109320577 A, 2019.).

[0007] In 2017, Marlene et al. reacted fusidic acid with the corresponding alcohol in DCM as solvent, EDCI and DMAP as catalysts at 25°C for 12 hours to synthesize fusidic acid C-21 substituted phenyl esterified derivatives (Bioorg. Med. Chem. Lett., 2017, 27: 658-661.).

[0008] In 2023, Liu et al. combined fusidic acid with the corresponding nitrogen-containing heterocyclic intermediates in DMF as solvent and K 2 CO 3 As an alkaline reagent, the reaction was carried out at 60°C for 4-6 hours to introduce a nitrogen-containing heterocycle into fusidic acid (Eur. J. Med. Chem., 2023, 259: 115697-115697.).

[0009] Traditional methods for synthesizing C-21 esterified derivatives of fusidic acid are mostly solvent reactions, which have disadvantages such as long reaction time, poor selectivity, and high toxicity of the solvents used. Therefore, they do not conform to the concept of green chemistry, are harmful to the environment, and hinder their industrial production. Therefore, the green synthesis of C-21 esterified derivatives of fusidic acid still needs further research.

[0010] Mechanochemistry and mechanical ball milling technology are green, efficient and environmentally friendly in drug synthesis. They are important means to achieve green chemistry and have the advantages of being fast, solvent-free, reproducible, selective and high yield. However, this technology has not been widely used in the derivatization of fusidic acid. If mechanical ball milling technology can be applied to the synthesis of fusidic acid C-21 ester derivatives, the efficiency of the synthesis can be improved and the synthesis process can be made more environmentally friendly, thereby promoting the derivatization research of fusidic acid. Summary of the invention

[0011] In view of the limitations of the prior art, the present application aims to provide an efficient and environmentally friendly method for modifying the structure of fusidic acid at C-21 to synthesize fusidic acid C-21 esterified derivatives.

[0012] In order to achieve the above object, the technical solution adopted by the present invention is:

[0013] A method for modifying the structure of C-21 of fusidic acid, the method comprising: adding several stainless steel grinding balls with a diameter of 8 to 10 mm into a stainless steel grinding pot, then sequentially adding a grinding aid, fusidic acid shown in formula (I), a substituted benzyl bromide reagent shown in formula (II), an alkaline reagent and a cosolvent, and then grinding at a certain grinding frequency; after grinding, scraping out the reactant, adding ethyl acetate to dissolve the reactant, filtering, and sequentially washing the liquid phase with 10% hydrochloric acid, water and saturated saline to obtain an organic phase, drying the organic phase with anhydrous sodium sulfate, filtering, concentrating the liquid phase, and purifying by column chromatography to obtain the fusidic acid C-21 esterified derivative shown in formula (IV). The reaction formula is as follows:

[0014]

[0015] In the above formula, R is -H, 2-NO 2 、3-NO 2 、4-NO 2 、2-CH 3 、3-CH 3 、4-CH 3 , one of 4-Br, 2-F, 3-F, 4-F, 4-Cl, and 4-CN.

[0016] Furthermore, the substituted benzyl bromide reagent is one of benzyl bromide, 2-nitrobenzyl bromide, 3-nitrobenzyl bromide, 4-nitrobenzyl bromide, 2-methylbenzyl bromide, 3-methylbenzyl bromide, 4-methylbenzyl bromide, 4-bromobenzyl bromide, 2-fluorobenzyl bromide, 3-fluorobenzyl bromide, 4-fluorobenzyl bromide, 4-chlorobenzyl bromide and 4-cyanobenzyl bromide.

[0017] Furthermore, the molar ratio of fusidic acid, substituted benzyl bromide reagent and alkaline reagent is 1:1.2:(1-2).

[0018] Furthermore, the alkaline reagent is any one of potassium carbonate, sodium hydroxide and potassium hydroxide.

[0019] Furthermore, the grinding aid is any one of silica gel, sodium chloride, anhydrous sodium sulfate, and neutral alumina.

[0020] Furthermore, the co-solvent is any one of ethyl acetate, acetone, anhydrous ethanol, DMF, DMSO, and THF.

[0021] Furthermore, the grinding frequency is 10 to 30 Hz; and the grinding time is 10 to 60 min.

[0022] Furthermore, the ratio of the added mass of the grinding aid to the amount of fusidic acid represented by formula (I) is 0.2-0.8:1, the mass unit is g, and the amount unit is mmol.

[0023] Furthermore, the ratio of the added volume of the co-solvent to the amount of fusidic acid represented by formula (I) is 0.4 to 1:1, the volume unit is L, and the amount unit is mol.

[0024] Furthermore, the column chromatography eluent is composed of ethyl acetate and petroleum ether in a volume ratio of 1: (4-20).

[0025] The mechanical grinding method described in the present invention is as follows: add the substrate mixture into a vibrating ball mill, and grind until the reaction is complete under the conditions that the grinding jar volume is 25 ml, the grinding frequency is 10-30 Hz, and the grinding ball diameter is 8 mm (preferably the grinding jar volume is 25 ml, the grinding frequency is 30 Hz, and the diameter of the stainless steel ball is 8 mm).

[0026] The method for separating and purifying the reaction mixture of the present invention is as follows: the entire reaction mixture is transferred out of the grinding tank, the grinding balls are taken out, the contents are dissolved with ethyl acetate, after being fully soaked, the mixture is filtered, washed, dried, and separated by silica gel column chromatography to obtain a pure product.

[0027] The present invention uses mechanical grinding technology to synthesize a series of fusidic acid C-21 esterified derivatives without catalyst and solvent. Compared with the existing chemical method, the present invention is simple to operate, mild reaction conditions, short reaction time, less pollution, and can effectively realize the synthesis of fusidic acid C-21 esterified derivatives. DETAILED DESCRIPTION

[0028] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] Synthesis of 21-fusidic acid benzyl ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), benzyl bromide (0.575 mmol), 98 mg K 2 CO 3As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 4:1, v / v), and obtain white crystals with a yield of 70.4%.

[0031] The NMR characterization data of the compound:

[0032] 1 H NMR (400 MHz, CDCl 3 )δ7.39-7.26(m,5H),5.87(d,J=8.4Hz,1H),5.20(d,J=12.2Hz,1H),5.05(t,J=7.2Hz,1H),4.92(d,J=12.2Hz ,1H),4.33(s,1H),3.74(d,J=2.4Hz,1H),3.03(d,J=10.9Hz,1H),2.53-2.39(m,2H),2.34-2.26(m,1H),2.20- 2.03(m,6H),1.92(s,3H),1.88-1.78(m,2H),1.78-1.69(m,2H),1.62(s,3H),1.60-1.54(m,3H),1.51(s,3H), 1.49-1.41(m,1H),1.36(s,3H),1.31-1.22(m,2H),1.17-1.03(m,2H),0.96(s,3H),0.92(s,3H),0.90(s,3H).

[0033] Embodiment 2:

[0034] Synthesis of 2-nitrobenzyl 21-fusidic acid ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 2-nitrobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 4:1, v / v), and obtain white crystals with a yield of 49.4%.

[0035] The NMR characterization data of the compound:

[0036] 1 H NMR (400 MHz, CDCl 3 )δ8.11(d,J=8.2Hz,1H),7.68-7.58(m,2H),7.51-7.45(m,1H),5.89(d,J=8.4Hz,1H),5.68(d,J=14.8Hz,1H),5.25(d,J =14.8Hz,1H),5.08(t,J=7.2Hz,1H),4.35(s,1H),3.75(d,J=2.4Hz,1H),3.07(d,J=10.7Hz,1H),2.56-2.40(m,2H),2.36 -2.28(m,1H),2.23-2.02(m,5H),1.95(s,3H),1.91-1.81(m,2H),1.79-1.70(m,2H),1.64(s,3H),1.62-1.57(m,4H),1. 55(s,3H),1.51-1.47(m,1H),1.38(s,3H),1.33-1.24(m,2H),1.18-1.06(m,2H),0.97(s,3H),0.92(s,3H),0.91(s,3H).

[0037] Embodiment 3:

[0038] Synthesis of 21-fusidic acid (3-nitrobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 3-nitrobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 54.3%.

[0039] The NMR characterization data of the compound:

[0040] 1 H NMR (400 MHz, CDCl 3)δ8.25-8.16(m,2H),7.70(d,J=7.7Hz,1H),7.55(t,J=7.9Hz,1H),5.89(d,J=8.3Hz,1H),5.29(d,J=12.8Hz,1H),5.05(t ,J=7.2Hz,1H),4.99(d,J=12.8Hz,1H),4.34(s,1H),3.75(d,J=2.7Hz,1H),3.06(d,J=10.5Hz,1H),2.55-2.39(m,2H),2. 34-2.27(m,1H),2.22-2.05(m,4H),1.94(s,3H),1.90-1.80(m,2H),1.79-1.70(m,2H),1.62(s,3H),1.59-1.54(m,5H),1 .52(s,3H),1.50-1.41(m,1H),1.37(s,3H),1.31-1.24(m,2H),1.17-1.03(m,2H),0.97(s,3H),0.92(s,3H),0.91(s,3H).

[0041] Embodiment 4:

[0042] Synthesis of 21-fusidic acid (4-nitrobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-nitrobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 93.5%.

[0043] The NMR characterization data of the compound:

[0044] 1 H NMR (400 MHz, CDCl 3)δ8.22(d,J=8.7Hz,2H),7.52(d,J=8.6Hz,2H),5.90(d,J=8.4Hz,1H),5.30(d,J=13.0Hz,1H),5.05(t,J=7.1 Hz,1H),4.98(d,J=13.2Hz,1H),4.34(s,1H),3.76(d,1H),3.06(d,J=12.2Hz,1H),2.55-2.39(m,2H),2.36-2 .26(m,1H),2.23-2.05(m,4H),1.94(s,3H),1.90-1.79(m,2H),1.80-1.70(m,2H),1.63(s,3H),1.58-1.55(m ,5H),1.53(s,3H),1.37(s,3H),1.34-1.24(m,4H),1.18-1.05(m,2H),0.97(s,3H),0.92(s,3H),0.90(s,3H).

[0045] Embodiment 5:

[0046] Synthesis of 2-methylbenzyl 21-fusidic acid ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 2-methylbenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 91.7%.

[0047] The NMR characterization data of the compound:

[0048] 1 H NMR (400 MHz, CDCl 3)δ7.32(d,J=7.1Hz,1H),7.24-7.14(m,3H),5.86(d,J=8.3Hz,1H),5.27(d,J=12.4Hz,1H),5.08-5.02(m,1H),4. 91(d,J=12.4Hz,1H),4.33(s,1H),3.75(d,J=2.8Hz,1H),3.02(d,J=12.0Hz,1H),2.50-2.38(m,2H),2.36-2.25(m ,4H),2.21-2.04(m,4H),1.93(s,3H),1.87-1.80(m,2H),1.77-1.70(m,2H),1.63(s,3H),1.60-1.53(m,5H),1.5 1(s,3H),1.42(s,1H),1.36(s,3H),1.29-1.24(m,2H),1.17-1.04(m,2H),0.97(s,3H),0.92(s,3H),0.90(s,3H).

[0049] Embodiment 6:

[0050] Synthesis of 21-fusidic acid (3-methylbenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 3-methylbenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 53.6%.

[0051] The NMR characterization data of the compound:

[0052] 1 H NMR (400 MHz, CDCl 3)δ7.25-7.20(m,1H),7.17-7.09(m,3H),5.86(d,J=8.3Hz,1H),5.16(d,J=12.1Hz,1H),5.05(t,J=7.2Hz,1H),4.88(d ,J=12.1Hz,1H),4.32(s,1H),3.73(d,J=2.7Hz,1H),3.02(d,J=11.8Hz,1H),2.52-2.36(m,2H),2.34(s,3H),2.32-2.2 5(m,1H),2.20-1.95(m,5H),1.92(s,3H),1.87-1.78(m,2H),1.76-1.68(m,4H),1.63(s,3H),1.61-1.53(m,3H),1.52 (s,3H),1.49-1.39(m,1H),1.36(s,3H),1.31-1.24(m,1H),1.16-1.02(m,2H),0.96(s,3H),0.91(s,3H),0.90(s,3H).

[0053] Embodiment 7:

[0054] Synthesis of 21-fusidic acid (4-methylbenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-methylbenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 50.2%.

[0055] The NMR characterization data of the compound:

[0056] 1 H NMR (400 MHz, CDCl 3)δ7.28(d,J=3.0Hz,2H),7.18(d,J=7.8Hz,2H),5.89(d,J=8.4Hz,1H),5.19(d,J=12.0Hz,1H),5.08(t,J=7.1Hz,1H),4 .90(d,J=12.1Hz,1H),4.35(s,1H),3.77(d,J=2.7Hz,1H),3.04(d,J=9.3Hz,1H),2.56-2.38(m,2H),2.36(s,3H),2.34- 2.27(m,1H),2.25-1.99(m,5H),1.96(s,3H),1.90-1.81(m,2H),1.80-1.71(m,2H),1.66(s,3H),1.63-1.56(m,5H),1.5 4(s,3H),1.52-1.44(m,1H),1.38(s,3H),1.33-1.27(m,1H),1.19-1.04(m,2H),0.99(s,3H),0.95(s,3H),0.93(s,3H).

[0057] Embodiment 8:

[0058] Synthesis of 21-fusidic acid (4-bromobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-bromobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 4:1, v / v), and obtain white crystals with a yield of 55.3%.

[0059] The NMR characterization data of the compound:

[0060] 1 H NMR (400 MHz, CDCl 3)δ7.49(d,J=8.4Hz,2H),7.26(d,J=20.6Hz,2H),5.88(d,J=8.4Hz,1H),5.16(d,J=12.4Hz,1H),5.06(t,J=7.2Hz,1H) ,4.87(d,J=12.4Hz,1H),4.35(s,1H),3.73(d,J=2.3Hz,1H),3.05(d,J=11.0Hz,1H),2.52-2.37(m,2H),2.34-2.27(m, 1H),2.22-2.07(m,7H),1.93(s,3H),1.88-1.79(m,2H),1.78-1.68(m,2H),1.64(s,3H),1.62-1.55(m,3H),1.52(s,3 H),1.50-1.42(m,1H),1.38(s,3H),1.28(d,J=12.1Hz,2H),1.20-1.03(m,2H),0.98(s,3H),0.92(s,3H),0.91(s,3H).

[0061] Embodiment 9:

[0062] Synthesis of 2-fluorobenzyl 21-fusidic acid ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 2-fluorobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 70.8%.

[0063] The NMR characterization data of the compound:

[0064] 1 H NMR (400 MHz, CDCl 3)δ7.43-7.29(m,2H),7.18-7.02(m,2H),5.86(d,J=8.4Hz,1H),5.29(d,J=12.5Hz,1H),5.06(t,J=7.4Hz,1H),4 .97(d,J=12.4Hz,1H),4.33(s,1H),3.75(d,J=3.1Hz,1H),3.03(d,J=12.3Hz,1H),2.45(q,J=10.3,9.7Hz,2H),2 .35-2.25(m,1H),2.22-2.03(m,4H),1.95(s,3H),1.88-1.78(m,2H),1.79-1.69(m,2H),1.63(s,3H),1.58-1.54 (m,5H),1.52(s,3H),1.36(s,3H),1.29-1.24(m,3H),1.16-1.06(m,2H),0.97(s,3H),0.92(s,3H),0.90(s,3H).

[0065] Embodiment 10:

[0066] Synthesis of 21-fusidic acid (3-fluorobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 3-fluorobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 74.2%.

[0067] The NMR characterization data of the compound:

[0068] 1 H NMR (400 MHz, CDCl 3)δ7.35-7.28(m,1H),7.15-6.97(m,3H),5.89(d,J=8.4Hz,2H),5.20(d,J=12.6Hz,1H),5.06(t,J=7.2Hz,1H),4. 90(d,J=12.5Hz,1H),4.33(s,1H),3.75(d,J=3.0Hz,1H),3.04(d,J=10.9Hz,1H),2.54-2.37(m,2H),2.36-2.26(m ,1H),2.22-2.05(m,4H),1.93(s,3H),1.89-1.80(m,2H),1.79-1.70(m,2H),1.63(s,3H),1.60-1.53(m,5H),1.5 3(s,3H),1.42(s,1H),1.37(s,3H),1.29-1.23(m,2H),1.18-1.04(m,2H),0.97(s,3H),0.92(s,3H),0.90(s,3H).

[0069] Embodiment 11:

[0070] Synthesis of 21-fusidic acid (4-fluorobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-fluorobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as cosolvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 52.6%.

[0071] The NMR characterization data of the compound:

[0072] 1 H NMR (400 MHz, CDCl 3)δ7.35-7.27(m,2H),7.06-6.99(m,2H),5.87(d,J=8.3Hz,1H),5.16(d,J=12.1Hz,1H),5.04(t,J=7.2Hz,1H),4.8 7(d,J=12.1Hz,1H),4.32(s,1H),3.74(d,J=2.7Hz,1H),3.03(d,J=13.1Hz,1H),2.52-2.34(m,2H),2.33-2.24(m,1 H),2.21-2.04(m,4H),1.93(s,3H),1.88-1.78(m,2H),1.78-1.69(m,2H),1.62(s,3H),1.60-1.53(m,6H),1.51(s, 3H),1.49-1.38(m,1H),1.36(s,3H),1.31-1.24(m,1H),1.17-1.02(m,2H),0.96(s,3H),0.92(s,3H),0.90(s,3H).

[0073] Embodiment 12:

[0074] Synthesis of 21-fusidic acid (4-chlorobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-chlorobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 45.3%.

[0075] The NMR characterization data of the compound:

[0076] 1 H NMR (400 MHz, CDCl 3)δ7.35-7.27(m,4H),5.86(d,J=8.3Hz,1H),5.15(d,J=12.3Hz,1H),5.03(t,J=7.3Hz,1H),4.86(d,J=12.3Hz ,1H),4.33(s,1H),3.72(d,J=2.8Hz,1H),3.03(d,J=10.3Hz,1H),2.50-2.36(m,2H),2.33-2.25(m,1H),2.20- 2.02(m,5H),1.91(s,3H),1.87-1.77(m,3H),1.75-1.67(m,2H),1.62(s,3H),1.60-1.51(m,3H),1.50(s,3H), 1.48-1.40(m,1H),1.35(s,3H),1.29-1.22(m,2H),1.16-1.03(m,2H),0.96(s,3H),0.91(s,3H),0.89(s,3H).

[0077] Embodiment 13:

[0078] Synthesis of 21-fusidic acid (4-cyanobenzyl) ester: Two stainless steel grinding balls with a diameter of 8 mm were added to a 25 ml stainless steel grinding jar, followed by the addition of grinding aid silica gel (300 mg), fusidic acid (0.475 mmol), 4-cyanobenzyl bromide (0.575 mmol), 98 mg K 2 CO 3 As alkaline reagent and 400μLDMSO as co-solvent, 30Hz, stop after 30min of reaction. After grinding, scrape out the reactant, add ethyl acetate to dissolve the reactant, filter and wash with 10% hydrochloric acid, water and saturated brine in turn, dry the organic phase with anhydrous sodium sulfate, filter and concentrate, column chromatography purification (the eluent used is petroleum ether: ethyl acetate = 6: 1, v / v), and obtain white crystals with a yield of 69.8%.

[0079] The NMR characterization data of the compound:

[0080] 1 H NMR (400 MHz, CDCl 3)δ7.65(d,J=8.2Hz,2H),7.46(d,J=8.0Hz,2H),5.89(d,J=8.4Hz,1H),5.25(d,J=13.1Hz,1H),5.05(t,J=7.3Hz,1H ),4.94(d,J=13.1Hz,1H),4.34(s,1H),3.76(d,J=2.9Hz,1H),3.05(d,J=12.0Hz,1H),2.55-2.36(m,2H),2.34-2.2 6(m,1H),2.23-2.03(m,4H),1.93(s,3H),1.87-1.78(m,2H),1.77-1.68(m,2H),1.63(s,3H),1.59-1.55(m,5H),1. 53(s,3H),1.42(s,1H),1.37(s,3H),1.31-1.25(m,2H),1.18-1.05(m,2H),0.97(s,3H),0.92(s,3H),0.90(s,3H).

[0081] Compared with the existing inventions, the characteristics of the present invention are mainly reflected in: the present invention provides a new method for synthesizing a C-21 esterified derivative of fusidic acid, which can react quickly in a short time and has a high yield.

[0082] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for modifying the C-21 structure of fusidic acid, characterized in that: The method comprises the following steps: adding a plurality of stainless steel grinding balls with a diameter of 8 to 10 mm into a stainless steel grinding pot, then sequentially adding a grinding aid, fusidic acid represented by formula (I), a substituted benzyl bromide reagent represented by formula (II), an alkaline reagent and a cosolvent, and then grinding at a certain grinding frequency; after grinding, scraping out the reactant, adding ethyl acetate to dissolve the reactant, filtering, and sequentially washing the liquid phase with 10% hydrochloric acid, water and saturated saline to obtain an organic phase, drying the organic phase with anhydrous sodium sulfate, filtering, concentrating the liquid phase, and purifying by column chromatography to obtain the fusidic acid C-21 esterified derivative represented by formula (IV); the reaction formula is as follows: In the above formula, R is one of -H, 2-NO2, 3-NO2, 4-NO2, 2-CH3, 3-CH3, 4-CH3, 4-Br, 2-F, 3-F, 4-F, 4-Cl, and 4-CN.

2. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The substituted benzyl bromide reagent is one of benzyl bromide, 2-nitrobenzyl bromide, 3-nitrobenzyl bromide, 4-nitrobenzyl bromide, 2-methylbenzyl bromide, 3-methylbenzyl bromide, 4-methylbenzyl bromide, 4-bromobenzyl bromide, 2-fluorobenzyl bromide, 3-fluorobenzyl bromide, 4-fluorobenzyl bromide, 4-chlorobenzyl bromide and 4-cyanobenzyl bromide.

3. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The molar ratio of fusidic acid, substituted benzyl bromide reagent and alkaline reagent is 1:1.2:(1~2).

4. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The alkaline reagent is any one of potassium carbonate, sodium hydroxide and potassium hydroxide.

5. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The grinding aid is any one of silica gel, sodium chloride, anhydrous sodium sulfate and neutral alumina.

6. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The co-solvent is any one of ethyl acetate, acetone, anhydrous ethanol, DMF, DMSO, and THF.

7. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The grinding frequency is 10 to 30 Hz; the grinding time is 10 to 60 minutes.

8. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The ratio of the added mass of the grinding aid to the amount of fusidic acid represented by formula (I) is 0.2-0.8:1, the mass unit is g, and the amount unit is mmol.

9. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The ratio of the added volume of the co-solvent to the amount of fusidic acid represented by formula (I) is (0.4-1):1, the volume unit is L, and the amount unit is mol.

10. The method for modifying the C-21 structure of fusidic acid according to claim 1, characterized in that: The column chromatography eluent is composed of ethyl acetate and petroleum ether in a volume ratio of 1: (4-20).

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