Process for the preparation of lugdunomycin

Abstract

The application provides a preparation method of Lugdunomycin and belongs to the technical field of compound synthesis. The compound actinaphthoran B and iso-maleimide are prepared into Lugdunomycin through intermolecular light-induced asymmetric Diels-Alder reaction, the synthesis method is simple, the condition is mild, the raw material is easy to obtain, the cost is low, the deficiency of natural Lugdunomycin is made up, and the demand of people for Lugdunomycin is met.

Description

Technical Field

[0001] This invention belongs to the field of compound synthesis technology, specifically relating to a method for preparing Lugdunomycin. Background Technology

[0002] Lugdunomycin was isolated from Streptomyces strain QL37 in 2019 and possesses a wide range of antibacterial and anticancer biological activities. However, lugdunomycin is relatively scarce and limited in quantity. Apart from its isolation from Streptomyces strain QL37, there is currently no chemical synthesis method for lugdunomycin, which limits its practical application.

[0003] Therefore, there is an urgent need for a chemical synthesis method for Lugdunomycin. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing lugdunomycin. This invention uses a chemical method to prepare lugdunomycin, overcoming the shortcomings of natural lugdunomycin and thus meeting people's demand for it.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing Lugdunomycin, comprising the following steps:

[0007] (1) Actinaphthoran B, iso-maleimide and the first solvent were mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to obtain compound A and compound B;

[0008] The structural formula of compound A is as follows: The structural formula of compound B is as follows:

[0009] (2) The compound B obtained in step (1), the second solvent and silica gel are mixed and subjected to a cyclization reaction to obtain Lugdunomycin;

[0010] Alternatively: (2) Mix the compound A obtained in step (1), iso-maleimide and the third solvent, and carry out the Diels-Alder reaction under mercury lamp irradiation to obtain compound B. Then mix the compound B, the second solvent and silica gel to carry out the cyclization reaction to obtain Lugdunomycin.

[0011] Preferably, the molar ratio of actinaphthoran B to iso-maleimide in step (1) is 1:(3-5).

[0012] Preferably, the first solvent in step (1) includes at least one of toluene, 1,4-dioxane and dimethyl sulfoxide.

[0013] Preferably, in step (1), the power of the mercury lamp is 400-500W and the maximum wavelength of the mercury lamp is 365nm.

[0014] Preferably, the temperature of the Diels-Alder reaction in step (1) is 20-30°C, and the reaction time is 46-50 h.

[0015] Preferably, the preparation method of iso-maleimide in step (1) includes the following steps:

[0016] 1) Mix 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester, reducing agent and solvent, and carry out reduction reaction to obtain intermediate product 1;

[0017] 2) The intermediate product 1 obtained in step 1) is mixed with triisopropyltrifluoromethanesulfonate, N,N-diisopropylethylamine and solvent, and hydroxyl groups are protected to obtain silyl ether;

[0018] 3) The silane ether obtained in step 2) is mixed with diisopropylaminolithium, I2 and solvent, and reacted at low temperature to obtain compound D;

[0019] 4) The compound D obtained in step 3) is mixed with a base and a solvent and subjected to a hydrolysis reaction to obtain crude acid;

[0020] 5) The crude acid obtained in step 4) is mixed with acetic anhydride and ammonium hydroxide to carry out a monoamidation reaction to obtain crude imide;

[0021] 6) The crude imide obtained in step 5) is mixed with trifluoroacetic anhydride and subjected to a cyclization reaction to obtain compound E;

[0022] 7) The compound E obtained in step 6) is mixed with tetrabutylammonium fluoride and a solvent to remove protection and obtain iso-maleimide.

[0023] Preferably, the preparation method of actinaphthoran B in step (1) includes the following steps:

[0024] a. 2-Bromo-6-methoxybenzoic acid is mixed with boron methyl sulfide and solvent to carry out a reduction reaction to obtain compound G;

[0025] b. Mix the compound G obtained in step a with chloromethyl ether, N,N-diisopropylethylamine and a solvent to protect the hydroxyl group, thereby obtaining compound H;

[0026] c. The compound H obtained in step b is mixed with n-butyllithium, solvent and compound I to carry out an addition reaction to obtain compound J;

[0027] d. The compound J obtained in step c is mixed with trifluoroacetic acid and a solvent to carry out a cyclization reaction to obtain compound K;

[0028] e. The compound K obtained in step d is mixed with hydrochloric acid and a solvent to remove protection, thereby obtaining compound actinaphthoran A;

[0029] f. The compound actinaphthoran A obtained in step e is mixed with sulfur trioxide pyridine complex, triethylamine and solvent, and subjected to an oxidation reaction to obtain actinaphthoran B.

[0030] Preferably, the preparation method of compound I in step c includes the following steps:

[0031] ① 2-hydroxy-4-methyl-3'-methoxybiphenyl was mixed with sodium hydride, iodomethane and solvent to carry out a substitution reaction, yielding compound M;

[0032] ② The compound M obtained in step ① is mixed with tert-butyllithium, N,N-dimethylformamide and solvent to carry out a formylation reaction to obtain compound O;

[0033] ③ The compound O obtained in step ② is mixed with boron tribromide and a solvent to remove protection, thereby obtaining compound I.

[0034] Preferably, in step (2), the mass ratio of compound B to silica gel is 1:(1-3).

[0035] Preferably, the cyclization reaction temperature in step (2) is 5–15°C, and the cyclization reaction time is 46–50 h.

[0036] This invention provides a method for preparing Lugdunomycin, comprising the following steps: (1) mixing actinaphthoran B, iso-maleimide, and a first solvent, and performing a Diels-Alder reaction under mercury lamp irradiation to obtain compound A and compound B; (2) mixing compound B obtained in step (1), a second solvent, and silica gel, and performing a cyclization reaction to obtain Lugdunomycin; or: (2) mixing compound A obtained in step (1), iso-maleimide, and a third solvent, and performing a Diels-Alder reaction under mercury lamp irradiation to obtain compound B, and then mixing compound B, a second solvent, and silica gel, and performing a cyclization reaction to obtain Lugdunomycin. This invention prepares Lugdunomycin from compound actinaphthoran B and iso-maleimide via an intermolecular photoinduced asymmetric Diels-Alder reaction. The synthesis method is simple, the conditions are mild, the raw materials are readily available, and the cost is low, thus compensating for the deficiencies of natural Lugdunomycin and meeting people's demand for Lugdunomycin. Attached Figure Description

[0037] Figure 1 The reaction formula for preparing compound D from compound C in step (1) of Example 1;

[0038] Figure 2 The 1H NMR spectrum of compound D prepared in step (1) of Example 1;

[0039] Figure 3 The carbon NMR spectrum of compound D prepared in step (1) of Example 1;

[0040] Figure 4 The reaction formula for preparing compound E from compound D in step (2) of Example 1;

[0041] Figure 5 The 1H NMR spectrum of compound E prepared in step (2) of Example 1;

[0042] Figure 6 The carbon NMR spectrum of compound E prepared in step (2) of Example 1;

[0043] Figure 7 The reaction formula for preparing compound iso-maleimide from compound E in step (3) of Example 1;

[0044] Figure 8 The 1H NMR spectrum of the compound iso-maleimide prepared in step (3) of Example 1;

[0045] Figure 9 The carbon NMR spectrum of the compound iso-maleimide prepared in step (3) of Example 1;

[0046] Figure 10 The reaction formula for preparing compound M from compound L in step (4) of Example 1;

[0047] Figure 11 The 1H NMR spectrum of compound M prepared in step (4) of Example 1;

[0048] Figure 12 The carbon NMR spectrum of compound M prepared in step (4) of Example 1;

[0049] Figure 13 The reaction formula for preparing compound O from compound M in step (5) of Example 1;

[0050] Figure 14 The 1H NMR spectrum of compound O prepared in step (5) of Example 1;

[0051] Figure 15 The carbon NMR spectrum of compound O prepared in step (5) of Example 1;

[0052] Figure 16 The reaction formula for preparing compound I from compound O in step (6) of Example 1;

[0053] Figure 17 The 1H NMR spectrum of compound I prepared in step (6) of Example 1;

[0054] Figure 18 The carbon NMR spectrum of compound I prepared in step (6) of Example 1;

[0055] Figure 19 The reaction formula for preparing compound G from compound F in step (7) of Example 1;

[0056] Figure 20 The 1H NMR spectrum of compound G prepared in step (7) of Example 1;

[0057] Figure 21 The carbon NMR spectrum of compound G prepared in step (7) of Example 1;

[0058] Figure 22 The reaction formula for preparing compound H from compound G in step (8) of Example 1;

[0059] Figure 23 The 1H NMR spectrum of compound H prepared in step (8) of Example 1;

[0060] Figure 24 The carbon NMR spectrum of compound H prepared in step (8) of Example 1;

[0061] Figure 25 The reaction formula for preparing compound J from compound H in step (9) of Example 1;

[0062] Figure 26 The 1H NMR spectrum of compound J prepared in step (9) of Example 1;

[0063] Figure 27 The carbon NMR spectrum of compound J prepared in step (9) of Example 1;

[0064] Figure 28 The reaction formula for preparing compound K from compound J in step (10) of Example 1;

[0065] Figure 29 The 1H NMR spectrum of compound K prepared in step (10) of Example 1;

[0066] Figure 30 The carbon NMR spectrum of compound K prepared in step (10) of Example 1;

[0067] Figure 31 The reaction formula for preparing compound actinaphthoran A from compound K in step (11) of Example 1;

[0068] Figure 32 The 1H NMR spectrum of the compound actinaphthoran A prepared in step (11) of Example 1;

[0069] Figure 33 The carbon NMR spectrum of compound actinaphthoran A prepared in step (11) of Example 1;

[0070] Figure 34 The reaction formula for preparing compound actinaphthoran B from compound actinaphthoran A in step (12) of Example 1;

[0071] Figure 35 The 1H NMR spectrum of the compound actinaphthoran B prepared in step (12) of Example 1;

[0072] Figure 36 The carbon NMR spectrum of the compound actinaphthoran B prepared in step (12) of Example 1;

[0073] Figure 37The reaction formula for preparing compounds A and B from compound actinaphthoran B in step (13) of Example 1;

[0074] Figure 38 The 1H NMR spectrum of compound A prepared in step (13) of Example 1;

[0075] Figure 39 The carbon NMR spectrum of compound A prepared in step (13) of Example 1;

[0076] Figure 40 The 1H NMR spectrum of compound B prepared in step (13) of Example 1;

[0077] Figure 41 The carbon NMR spectrum of compound B prepared in step (13) of Example 1;

[0078] Figure 42 The reaction formula for preparing Lugdunomycin from compound B in step (14) of Example 1;

[0079] Figure 43 The 1H NMR spectrum of Lugdunomycin prepared in step (14) of Example 1;

[0080] Figure 44 The image shows the carbon NMR spectrum of Lugdunomycin prepared in step (14) of Example 1. Detailed Implementation

[0081] This invention provides a method for preparing Lugdunomycin, comprising the following steps:

[0082] (1) Actinaphthoran B, iso-maleimide and the first solvent were mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to obtain compound A and compound B;

[0083] (2) The compound B obtained in step (1), the second solvent and silica gel are mixed and subjected to a cyclization reaction to obtain Lugdunomycin;

[0084] Alternatively: (2) Mix the compound A obtained in step (1), iso-maleimide and the third solvent, and carry out the Diels-Alder reaction under mercury lamp irradiation to obtain compound B. Then mix the compound B, the second solvent and silica gel to carry out the cyclization reaction to obtain Lugdunomycin.

[0085] Unless otherwise specified, the present invention does not impose any special restrictions on the source of the raw materials, and commercially available products well known to those skilled in the art can be used.

[0086] In this invention, actinaphthoran B, isomaleimide, and a first solvent are mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to obtain compound A and compound B.

[0087] In this invention, the structural formula of the actinaphthoran B is as follows:

[0088] In this invention, the method for preparing actinaphthoran B preferably includes the following steps:

[0089] a. 2-Bromo-6-methoxybenzoic acid is mixed with boron methyl sulfide and solvent to carry out a reduction reaction to obtain compound G;

[0090] b. Mix the compound G obtained in step a with chloromethyl ether, N,N-diisopropylethylamine and a solvent to protect the hydroxyl group, thereby obtaining compound H;

[0091] c. The compound H obtained in step b is mixed with n-butyllithium, solvent and compound I to carry out an addition reaction to obtain compound J;

[0092] d. The compound J obtained in step c is mixed with trifluoroacetic acid and a solvent to carry out a cyclization reaction to obtain compound K;

[0093] e. The compound K obtained in step d is mixed with hydrochloric acid and a solvent to remove protection, thereby obtaining compound actinaphthoran A;

[0094] f. The compound actinaphthoran A obtained in step e is mixed with sulfur trioxide pyridine complex, triethylamine and solvent, and subjected to an oxidation reaction to obtain actinaphthoran B.

[0095] In this invention, 2-bromo-6-methoxybenzoic acid is mixed with boron methyl sulfide and a solvent to carry out a reduction reaction to obtain compound G.

[0096] In this invention, the structural formula of the 2-bromo-6-methoxybenzoic acid is as follows:

[0097] In this invention, the molar ratio of 2-bromo-6-methoxybenzoic acid to boron methyl sulfide is preferably 1:(1-3), more preferably 1:2.

[0098] In this invention, the solvent is preferably tetrahydrofuran and dimethyl sulfide (DMS).

[0099] In this invention, the preferred method for mixing 2-bromo-6-methoxybenzoic acid with borane methyl sulfide and a solvent is as follows: 2-bromo-6-methoxybenzoic acid and tetrahydrofuran are mixed to obtain mixture A; borane methyl sulfide and dimethyl sulfide are mixed to obtain mixture B; and then mixture B is slowly added to mixture A at -2 to 2°C. This invention does not impose any specific limitation on the exact rate at which mixture B is slowly added; a relatively slow rate is acceptable.

[0100] In this invention, the preferred molar ratio of 2-bromo-6-methoxybenzoic acid to the volume ratio of tetrahydrofuran is 43.49 mmol:(200-400) mL, more preferably 43.49 mmol:300 mL.

[0101] In this invention, the concentration of borane methyl sulfide in the mixture B is preferably 9–11 mol / L, more preferably 10 mol / L. This invention does not impose any particular limitation on the amount of dimethyl sulfide used, as long as the concentration of borane methyl sulfide in the mixture B is within the above range.

[0102] In this invention, the temperature of the reduction reaction is preferably 50–70°C, more preferably 60°C; the time of the reduction reaction is preferably 5–7 hours, more preferably 6 hours; and the reduction reaction is preferably carried out under stirring conditions. This invention does not impose any particular limitation on the stirring method and rate; stirring methods and rates well known to those skilled in the art can be used. By controlling the amount of each raw material, the mixing method, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0103] After the reduction reaction is completed, the present invention preferably adds methanol to the system after the reduction reaction at -2 to 2°C to quench the reaction, and then performs rotary evaporation and column chromatography in sequence to obtain compound G.

[0104] The present invention does not impose any special limitation on the amount of methanol used; any technical solution known to those skilled in the art can be used.

[0105] The present invention does not impose any special limitations on the operation of rotary evaporation; solvent removal can be achieved by using rotary evaporation techniques well known to those skilled in the art.

[0106] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane in a volume ratio of 1:(3-5), more preferably a mixture of ethyl acetate and n-hexane in a volume ratio of 1:4. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0107] In this invention, the structural formula of compound G is as follows:

[0108] After obtaining compound G, the present invention preferably mixes compound G with chloromethyl ether, N,N-diisopropylethylamine and a solvent to protect the hydroxyl group, thereby obtaining compound H.

[0109] In this invention, the molar ratio of compound G to N,N-diisopropylethylamine is preferably 1:(2 to 2.5), more preferably 1:2.2.

[0110] In this invention, the molar ratio of compound G to chloromethyl ether is preferably 1:(3 to 3.5), more preferably 1:3.1.

[0111] In this invention, the solvent is preferably dichloromethane.

[0112] In this invention, the preferred molar ratio of compound G to solvent volume is 35.19 mmol:(100-300) mL, more preferably 35.19 mmol:200 mL.

[0113] In this invention, the preferred method for mixing compound G with chloromethyl ether, N,N-diisopropylethylamine, and a solvent is to mix compound G, N,N-diisopropylethylamine, and a solvent, and then slowly add chloromethyl ether. This invention does not impose any specific limitation on the exact rate at which the chloromethyl ether is slowly added; a relatively slow rate is acceptable.

[0114] In this invention, the temperature for hydroxyl protection is preferably room temperature; the duration of hydroxyl protection is preferably 15–18 hours, more preferably 16 hours. By controlling the amount of each raw material, the reaction temperature, and the time within the above ranges, this invention ensures that the reaction proceeds fully.

[0115] After hydroxyl protection is completed, the reaction is preferably quenched by adding a saturated ammonium chloride aqueous solution, followed by extraction with dichloromethane. The organic layer is dried with sodium sulfate, and then subjected to rotary evaporation and column chromatography to obtain compound H.

[0116] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0117] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(9-11), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:10. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0118] In this invention, the structural formula of compound H is as follows:

[0119] After obtaining compound H, the present invention preferably mixes compound H with n-butyllithium, solvent and compound I to carry out an addition reaction to obtain compound J.

[0120] In this invention, the molar ratio of compound H to n-butyllithium is preferably (2-4):1, more preferably 3:1.

[0121] In this invention, the molar ratio of compound H to compound I is preferably (2-4):1, more preferably 3:1.

[0122] In this invention, the structural formula of compound I is as follows:

[0123] In this invention, the preparation method of compound I preferably includes the following steps:

[0124] ① 2-hydroxy-4-methyl-3'-methoxybiphenyl was mixed with sodium hydride, iodomethane and solvent to carry out a substitution reaction, yielding compound M;

[0125] ② The compound M obtained in step ① is mixed with tert-butyllithium, N,N-dimethylformamide and solvent to carry out a formylation reaction to obtain compound O;

[0126] ③ The compound O obtained in step ② is mixed with boron tribromide and a solvent to remove protection, thereby obtaining compound I.

[0127] In this invention, 2-hydroxy-4-methyl-3'-methoxybiphenyl is mixed with sodium hydride, iodomethane and a solvent to carry out a substitution reaction to obtain compound M.

[0128] In this invention, the structural formula of the 2-hydroxy-4-methyl-3'-methoxybiphenyl is as follows:

[0129] In this invention, the molar ratio of 2-hydroxy-4-methyl-3'-methoxybiphenyl to sodium hydride is preferably 1:(0.4-0.6), more preferably 1:0.5.

[0130] In this invention, the molar ratio of 2-hydroxy-4-methyl-3'-methoxybiphenyl to iodomethane is preferably 1:(1 to 1.5), more preferably 1:1.1.

[0131] In this invention, the solvent is preferably tetrahydrofuran.

[0132] In this invention, the preferred molar ratio of 2-hydroxy-4-methyl-3'-methoxybiphenyl to solvent volume is 79.75 mmol:(400-600) mL, more preferably 79.75 mmol:500 mL.

[0133] In this invention, the preferred method for mixing the 2-hydroxy-4-methyl-3'-methoxybiphenyl with sodium hydride, iodomethane, and solvent is as follows: mixing the 2-hydroxy-4-methyl-3'-methoxybiphenyl with the solvent, then slowly adding sodium hydride at -2 to 2°C, stirring at room temperature for 20 to 40 minutes, and then adding iodomethane; more preferably, mixing the 2-hydroxy-4-methyl-3'-methoxybiphenyl with the solvent, then slowly adding sodium hydride at 0°C, stirring at room temperature for 30 minutes, and then adding iodomethane. This invention does not impose any particular limitation on the specific rate of addition of sodium hydride; any technical solution well-known to those skilled in the art can be used.

[0134] In this invention, the temperature of the substitution reaction is preferably room temperature; the time of the substitution reaction is preferably 7-9 hours, more preferably 8 hours. By controlling the amount of each component, the reaction temperature, and the time within the above ranges, this invention ensures that the reaction proceeds fully.

[0135] After the substitution reaction is completed, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with diethyl ether, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain compound M.

[0136] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0137] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(48-52), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:50. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0138] In this invention, the structural formula of compound M is as follows:

[0139] After obtaining compound M, the present invention preferably mixes compound M with tert-butyllithium, N,N-dimethylformamide and solvent to carry out a formylation reaction to obtain compound O.

[0140] In this invention, the molar ratio of compound M to tert-butyllithium is preferably 1:(0.9 to 1.1), more preferably 1:1.

[0141] In this invention, the molar ratio of compound M to N,N-dimethylformamide is preferably 1:(1 to 1.5), more preferably 1:1.1.

[0142] In this invention, the solvent is preferably benzene and pentane.

[0143] In this invention, the preferred method for mixing compound M with tert-butyllithium, N,N-dimethylformamide, and a solvent is as follows: Compound M is mixed with benzene to obtain mixture A; tert-butyllithium is mixed with pentane to obtain mixture B; mixture B is slowly added to mixture A at -2 to 2°C; the mixture is stirred at room temperature for 15 to 20 hours; and then N,N-dimethylformamide is added at -2 to 2°C. This invention does not impose a specific limitation on the exact rate of addition of mixture B; any technical solution well-known to those skilled in the art can be used.

[0144] In this invention, the preferred molar ratio of compound M to benzene is 39.58 mmol:(200-400) mL, more preferably 39.58 mmol:300 mL.

[0145] In this invention, the concentration of tert-butyllithium in the mixture B is preferably 1–1.5 mol / L, more preferably 1.3 mol / L. This invention does not impose any particular limitation on the amount of pentane used, as long as the concentration of tert-butyllithium in the mixture B is within the above-mentioned range.

[0146] In this invention, the formylation reaction temperature is preferably room temperature; the formylation reaction time is preferably 1-3 hours, more preferably 2 hours; and the formylation reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0147] After the formylation reaction is completed, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with diethyl ether, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain compound O.

[0148] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0149] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(28-32), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:30. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0150] In this invention, the structural formula of compound O is as follows:

[0151] After obtaining compound O, the present invention preferably mixes compound O with boron tribromide and a solvent to perform deprotection, thereby obtaining compound I.

[0152] In this invention, the molar ratio of compound O to boron tribromide is preferably 1:(2-4), more preferably 1:3.

[0153] In this invention, the solvent is preferably dichloromethane.

[0154] In this invention, the preferred molar ratio of compound O to solvent volume is 19.56 mmol:(80-120) mL, more preferably 19.56 mmol:100 mL.

[0155] In this invention, the preferred method for mixing compound O with boron tribromide and the solvent is to mix compound O and the solvent, and then slowly add boron tribromide at -2 to 2°C. This invention does not impose any particular limitation on the specific rate of addition of the slowly added boron tribromide; any technical solution well-known to those skilled in the art can be used.

[0156] In this invention, the deprotection temperature is preferably -2 to 2°C, more preferably 0°C; the deprotection time is preferably 1 to 3 hours, more preferably 2 hours; and the deprotection is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0157] After deprotection, the present invention preferably adds water to quench the reaction, then extracts with ethyl acetate, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain compound I.

[0158] The present invention does not impose any special limitations on the amount of water used, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0159] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate, n-hexane, and methanol in a volume ratio of (4-6):(8-12):1, more preferably a mixture of ethyl acetate, n-hexane, and methanol in a volume ratio of 5:10:1. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0160] In this invention, the solvent used when compound H reacts with n-butyllithium, the solvent, and compound I is preferably tetrahydrofuran and pentane.

[0161] In this invention, the preferred method for mixing compound H with n-butyllithium, the solvent, and compound I is as follows: compound H is mixed with tetrahydrofuran to obtain mixture A; n-butyllithium is mixed with pentane to obtain mixture B; mixture B is slowly added to mixture A at -75 to -80°C, and the mixture is stirred for 30 to 50 minutes; then compound I is added. This invention does not impose a specific limitation on the exact rate of addition of mixture B; any technical solution well-known to those skilled in the art can be used.

[0162] In this invention, the preferred molar ratio of compound H to the volume ratio of tetrahydrofuran is 17.31 mmol:(100-300) mL, more preferably 17.31 mmol:200 mL.

[0163] In this invention, the concentration of n-butyllithium in the mixture B is preferably 1.5–2.0 mol / L, more preferably 1.6 mol / L. This invention does not impose any special limitation on the amount of pentane used, as long as the concentration of n-butyllithium in the mixture B is within the above-mentioned range.

[0164] In this invention, the temperature of the addition reaction is preferably -75 to -80°C, more preferably -78°C; the time of the addition reaction is preferably 0.5 to 1.5 hours, more preferably 1 hour; and the addition reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0165] After the addition reaction is completed, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with ethyl acetate, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain compound J.

[0166] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0167] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane in a volume ratio of 1:(1-3), more preferably a mixture of ethyl acetate and n-hexane in a volume ratio of 1:2. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0168] In this invention, the structural formula of compound J is as follows:

[0169] After obtaining compound J, the present invention preferably mixes compound J with trifluoroacetic acid and a solvent to carry out a cyclization reaction to obtain compound K.

[0170] In this invention, the molar ratio of compound J to trifluoroacetic acid is preferably 1:(1-3), more preferably 1:2.

[0171] In this invention, the solvent is preferably dichloromethane.

[0172] In this invention, the preferred molar ratio of compound J to solvent volume is 2.86 mmol:(200-400) mL, more preferably 2.86 mmol:300 mL.

[0173] In this invention, the preferred method for mixing compound J with trifluoroacetic acid and a solvent is to mix compound J and the solvent, and then slowly add trifluoroacetic acid at -2 to 2°C. This invention does not impose any specific limitation on the exact rate of addition of the slowly added trifluoroacetic acid; any technical solution well-known to those skilled in the art can be used.

[0174] In this invention, the preferred temperature for the cyclization reaction is -2 to 2°C, more preferably 0°C; the preferred time for the cyclization reaction is 0.5 to 1.5 hours, more preferably 1 hour; and the cyclization reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0175] After the cyclization reaction is completed, the present invention preferably adds a saturated sodium bicarbonate aqueous solution to quench the reaction, then extracts with dichloromethane, and performs rotary evaporation and column chromatography on the organic layer to obtain compound K.

[0176] The present invention does not impose any special limitations on the amount of the saturated sodium bicarbonate aqueous solution, the extraction and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0177] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(6-10), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:8. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0178] In this invention, the structural formula of compound K is as follows:

[0179] After obtaining compound K, the present invention preferably mixes compound K with hydrochloric acid and solvent to perform deprotection, thereby obtaining compound actinaphthoran A.

[0180] In this invention, the concentration of the hydrochloric acid is preferably 4 to 6 mol / L, more preferably 5 mol / L.

[0181] In this invention, the preferred molar ratio of compound K to hydrochloric acid is 1.45 mmol: (8-12) mL, more preferably 1.45 mmol: 10 mL.

[0182] In this invention, the solvent is preferably tetrahydrofuran.

[0183] In this invention, the preferred molar ratio of compound K to solvent volume is 1.45 mmol:(30-50) mL, more preferably 1.45 mmol:40 mL.

[0184] In this invention, the preferred method for mixing compound K with hydrochloric acid and solvent is to mix compound K and solvent, and then add hydrochloric acid at room temperature.

[0185] In this invention, the deprotection temperature is preferably 30–50°C, more preferably 40°C; the deprotection time is preferably 12–18 hours, more preferably 16 hours; and the deprotection is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0186] After deprotection, the present invention preferably adds a saturated sodium bicarbonate aqueous solution to quench the reaction, then extracts with dichloromethane, and performs rotary evaporation and column chromatography on the organic layer to obtain the compound actinaphthoran A.

[0187] The present invention does not impose any special limitations on the amount of the saturated sodium bicarbonate aqueous solution, the extraction and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0188] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(5-7), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:6. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0189] In this invention, the structural formula of the compound actinaphthoranA is as follows:

[0190] After obtaining compound actinaphthoran A, the present invention preferably mixes the compound actinaphthoran A with a sulfur trioxide pyridine complex, triethylamine and a solvent to carry out an oxidation reaction to obtain actinaphthoran B.

[0191] In this invention, the molar ratio of the compound actinaphthoranA and the sulfur trioxide pyridine complex is preferably 1:(1-3), more preferably 1:2.

[0192] In this invention, the molar ratio of the compound actinaphthoran A to triethylamine is preferably 1:(2-4), more preferably 1:3.

[0193] In this invention, the solvent is preferably dimethyl sulfoxide.

[0194] In this invention, the preferred molar ratio of the compound actinaphthoranA to the volume ratio of the solvent is 0.37 mmol: (5-10) mL, more preferably 0.37 mmol: 8 mL.

[0195] In this invention, the preferred method for mixing the compound actinaphthoranA with the sulfur trioxide pyridine complex, triethylamine, and solvent is to mix the compound actinaphthoranA, the sulfur trioxide pyridine complex, and the solvent, and then add triethylamine at room temperature.

[0196] In this invention, the oxidation reaction temperature is preferably room temperature; the oxidation reaction time is preferably 1-3 hours, more preferably 2 hours; and the oxidation reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0197] After the oxidation reaction is complete, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with diethyl ether, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain actinaphthoran B.

[0198] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0199] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(8-12), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:10. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0200] In this invention, the structural formula of iso-maleimide is:

[0201] In this invention, the method for preparing iso-maleimide preferably includes the following steps:

[0202] 1) Mix 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester, reducing agent and solvent, and carry out reduction reaction to obtain intermediate product 1;

[0203] 2) The intermediate product 1 obtained in step 1) is mixed with triisopropyltrifluoromethanesulfonate, N,N-diisopropylethylamine and solvent, and hydroxyl groups are protected to obtain silyl ether;

[0204] 3) The silane ether obtained in step 2) is mixed with diisopropylaminolithium, I2 and solvent, and reacted at low temperature to obtain compound D;

[0205] 4) The compound D obtained in step 3) is mixed with a base and a solvent and subjected to a hydrolysis reaction to obtain crude acid;

[0206] 5) The crude acid obtained in step 4) is mixed with acetic anhydride and ammonium hydroxide to carry out a monoamidation reaction to obtain crude imide;

[0207] 6) The crude imide obtained in step 5) is mixed with trifluoroacetic anhydride and subjected to a cyclization reaction to obtain compound E;

[0208] 7) The compound E obtained in step 6) is mixed with tetrabutylammonium fluoride and a solvent to remove protection and obtain iso-maleimide.

[0209] In this invention, 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester, a reducing agent, and a solvent are mixed to carry out a reduction reaction to obtain intermediate product 1.

[0210] In this invention, the structural formula of the 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester is as follows:

[0211] In this invention, the reducing agent is preferably sodium borohydride.

[0212] In this invention, the molar ratio of the 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester to the reducing agent is preferably 1:(0.4-0.6), more preferably 1:0.5.

[0213] In this invention, the solvent is preferably methanol.

[0214] In this invention, the preferred molar ratio of the 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester to the solvent is 124.95 mmol:(400-600) mL, more preferably 124.95 mmol:500 mL.

[0215] In this invention, the preferred method for mixing the 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester, the reducing agent, and the solvent is to mix the 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester and the solvent, and then slowly add the reducing agent at -2 to 2°C. This invention does not impose any specific limitation on the exact rate at which the reducing agent is slowly added; any technical solution well-known to those skilled in the art can be used.

[0216] In this invention, the temperature of the reduction reaction is preferably -2 to 2°C, more preferably 0°C; the time of the reduction reaction is preferably 0.5 to 1.5 hours, more preferably 1 hour; and the reduction reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0217] After the reduction reaction is completed, hydrochloric acid is preferably added to quench the reaction, followed by extraction with ethyl acetate. The organic layer is dried with sodium sulfate and then rotary evaporated to obtain intermediate product 1.

[0218] The present invention does not impose any special limitations on the concentration and amount of hydrochloric acid, or on the extraction, drying and rotary evaporation operations; any technical solutions known to those skilled in the art can be used.

[0219] After obtaining intermediate product 1, the present invention preferably mixes intermediate product 1 with triisopropyltrifluoromethanesulfonate, N,N-diisopropylethylamine and solvent to protect the hydroxyl groups, thereby obtaining silyl ether.

[0220] In this invention, the molar ratio of intermediate product 1 to N,N-diisopropylethylamine is preferably 1:(1 to 1.5), more preferably 1:1.2.

[0221] In this invention, the molar ratio of intermediate product 1 to triisopropyltrifluoromethanesulfonate is preferably 1:(1 to 1.5), more preferably 1:1.05.

[0222] In this invention, the solvent is preferably dichloromethane.

[0223] In this invention, the preferred molar ratio of intermediate product 1 to solvent volume is 112.52 mmol:(600-800) mL, more preferably 112.52 mmol:700 mL.

[0224] In this invention, the preferred method for mixing intermediate 1 with triisopropyltrifluoromethanesulfonate, N,N-diisopropylethylamine, and the solvent is to mix intermediate 1, N,N-diisopropylethylamine, and the solvent, and then slowly add triisopropyltrifluoromethanesulfonate at -75 to -80°C. This invention does not impose any specific limitation on the exact rate of addition of triisopropyltrifluoromethanesulfonate; any technical solution well-known to those skilled in the art can be used.

[0225] In this invention, the preferred temperature for hydroxyl protection is -75 to -80°C, more preferably -78°C; the preferred time for hydroxyl protection is 1 to 2 hours, more preferably 1.5 hours; and the hydroxyl protection is preferably carried out under stirring conditions. This invention does not impose any particular limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0226] After hydroxyl protection is completed, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with dichloromethane, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain silyl ether.

[0227] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0228] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(18-22), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:20. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0229] After obtaining the silyl ether, the present invention preferably mixes the silyl ether with diisopropylaminolithium, I2 and a solvent, and performs a low-temperature reaction to obtain compound D.

[0230] In this invention, the molar ratio of the silyl ether to diisopropylaminolithium is preferably 1:(1-3), more preferably 1:2.

[0231] In this invention, the molar ratio of the silyl ether to I2 is preferably 1:(0.9 to 1.1), more preferably 1:1.

[0232] In this invention, the solvent is preferably tetrahydrofuran.

[0233] In this invention, the preferred method for mixing the silane ether with diisopropylaminolithium, I2 and solvent is as follows: at -75 to -80°C, the silane ether and a portion of the solvent are mixed to obtain mixture A, the diisopropylaminolithium and the remaining solvent are mixed to obtain mixture B, then mixture B is added dropwise to mixture A, stirred for 0.5 to 1.5 hours, and then I2 is added.

[0234] In this invention, the preferred molar ratio of the silyl ether to the volume ratio of a portion of the solvent is 102.36 mmol:(500-700) mL, more preferably 102.36 mmol:600 mL.

[0235] In this invention, the concentration of diisopropylaminolithium in the mixture B is preferably 1-3 mol / L, more preferably 2 mol / L. This invention does not have a specific limitation on the amount of the remaining solvent, as long as the concentration of diisopropylaminolithium in the mixture B is within the above range.

[0236] In this invention, the temperature of the low-temperature reaction is preferably -75 to -80°C, more preferably -78°C; the reaction time is preferably 1 to 3 hours, more preferably 2 hours; and the low-temperature reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0237] After the low-temperature process is completed, the present invention preferably adds a saturated sodium sulfite aqueous solution to quench the reaction, then extracts with dichloromethane, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain compound D.

[0238] The present invention does not impose any special limitations on the amount of the saturated sodium sulfite aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0239] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(14-16), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:15. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0240] In this invention, the structural formula of compound D is as follows:

[0241] After obtaining compound D, the present invention preferably mixes compound D with a base and a solvent to carry out a hydrolysis reaction to obtain crude acid.

[0242] In this invention, the alkali is preferably sodium hydroxide.

[0243] In this invention, the molar ratio of compound D to base is preferably 1:(5-7), more preferably 1:6.

[0244] In this invention, the solvent is preferably methanol.

[0245] In this invention, the preferred molar ratio of compound D to solvent volume is 14.04 mmol:(80-120) mL, more preferably 14.04 mmol:100 mL.

[0246] In this invention, the preferred method for mixing compound D with alkali and solvent is to mix compound D and solvent, and then add alkali at -2 to 2°C.

[0247] In this invention, the hydrolysis reaction temperature is preferably room temperature; the hydrolysis reaction time is preferably 3-5 hours, more preferably 4 hours; and the hydrolysis reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0248] After the hydrolysis reaction is completed, hydrochloric acid is preferably added to quench the reaction, followed by extraction with dichloromethane, drying of the organic layer with sodium sulfate, and then rotary evaporation to obtain crude acid.

[0249] The present invention does not impose any special limitations on the concentration and amount of hydrochloric acid, or on the extraction, drying and rotary evaporation operations; any technical solutions known to those skilled in the art can be used.

[0250] After obtaining the crude acid, the present invention preferably mixes the crude acid with acetic anhydride and ammonium hydroxide to carry out a monoamidation reaction to obtain crude imide.

[0251] In this invention, the preferred molar ratio of crude acid to acetic anhydride is 12.34 mmol:(8-12) mL, more preferably 12.34 mmol:10 mL.

[0252] In this invention, the mass concentration of the ammonium hydroxide is preferably 28%.

[0253] In this invention, the preferred molar ratio of crude acid to ammonium hydroxide is 12.34 mmol:(8-12) mL, more preferably 12.34 mmol:10 mL.

[0254] In this invention, crude acid and acetic anhydride are preferably mixed and reacted at room temperature with stirring for 15–17 hours, followed by rotary evaporation, cooling in an ice bath, and then slowly adding ammonium hydroxide for a monoamidation reaction for 5–15 minutes. This invention does not have a specific limitation on the exact rate of addition of the slowly added ammonium hydroxide; any technique well-known to those skilled in the art can be used. By controlling the amount of each raw material, reaction temperature, and time within the aforementioned ranges, this invention ensures a complete reaction.

[0255] After the monoamidation reaction is completed, the present invention preferably acidifies the product after the monoamidation reaction, and then filters, washes and dries it in sequence to obtain crude imide.

[0256] In this invention, the acidification is preferably achieved by slowly adding 0.5 to 1.5 mol / L hydrochloric acid until the pH value is 5 to 7, and more preferably by slowly adding 1 mol / L hydrochloric acid until the pH value is 6.

[0257] The present invention does not impose any special limitations on the filtering, washing and drying operations, and any technical solutions known to those skilled in the art can be used.

[0258] After obtaining the crude imide, the present invention preferably mixes the crude imide with trifluoroacetic anhydride and carries out a cyclization reaction to obtain compound E.

[0259] In this invention, the preferred molar ratio of crude imide to trifluoroacetic anhydride is 11.74 mmol:(20-40) mL, more preferably 11.74 mmol:30 mL.

[0260] In this invention, the temperature of the cyclization reaction is preferably 30–50°C, more preferably 40°C; the time of the cyclization reaction is preferably 15–18 hours, more preferably 16 hours; and the cyclization reaction is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used.

[0261] After the cyclization reaction is completed, the product of the cyclization reaction is preferably subjected to vacuum distillation and column chromatography in sequence to obtain compound E.

[0262] The present invention does not impose any special limitations on the operation of the vacuum distillation, and any technical solution known to those skilled in the art can be used.

[0263] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:(14-16), more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 1:15. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0264] In this invention, the structural formula of compound E is as follows:

[0265] After obtaining compound E, the present invention preferably mixes compound E with tetrabutylammonium fluoride and a solvent to perform deprotection, thereby obtaining iso-maleimide.

[0266] In this invention, the molar ratio of compound E to tetrabutylammonium fluoride is preferably 1:(1-2), more preferably 1:1.5.

[0267] In this invention, the solvent is preferably tetrahydrofuran.

[0268] In this invention, the preferred method for mixing compound E with tetrabutylammonium fluoride and solvent is to mix compound E with a portion of the solvent to obtain mixture A, mix tetrabutylammonium fluoride with the remaining solvent to obtain mixture B, and then mix mixture B with mixture A.

[0269] In this invention, the preferred molar ratio of compound E to the volume ratio of a portion of the solvent is 6.47 mmol:(50-70) mL, more preferably 6.47 mmol:60 mL.

[0270] In this invention, the concentration of tetrabutylammonium fluoride in the mixture B is preferably 0.5–1.5 mol / L, more preferably 1 mol / L. This invention does not have a specific limitation on the amount of the remaining solvent, as long as the concentration of tetrabutylammonium fluoride in the mixture B is within the above-mentioned range.

[0271] In this invention, the deprotection temperature is preferably room temperature; the deprotection time is preferably 1-3 hours, more preferably 2 hours; and the deprotection is preferably carried out under stirring conditions. This invention does not impose any special limitations on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0272] After deprotection, the present invention preferably adds a saturated ammonium chloride aqueous solution to quench the reaction, then extracts with ethyl acetate, dries the organic layer with sodium sulfate, and then performs rotary evaporation and column chromatography in sequence to obtain iso-maleimide.

[0273] The present invention does not impose any special limitations on the amount of the saturated ammonium chloride aqueous solution, the extraction, drying and rotary evaporation operations, and any technical solutions known to those skilled in the art can be used.

[0274] In this invention, silica gel is preferably used for column chromatography; the mobile phase for column chromatography is preferably a mixture of ethyl acetate and n-hexane with a volume ratio of (3-5):1, more preferably a mixture of ethyl acetate and n-hexane with a volume ratio of 4:1. This invention does not impose any special limitations on other operations of the column chromatography; techniques well known to those skilled in the art can be used.

[0275] In this invention, the molar ratio of actinaphthoran B to iso-maleimide is preferably 1:(3-5), more preferably 1:4.

[0276] In this invention, the first solvent preferably includes at least one of toluene, 1,4-dioxane, and dimethyl sulfoxide.

[0277] In this invention, the preferred molar ratio of actinaphthoran B to the volume ratio of the first solvent is 0.10 mmol:(0.2-0.3) mL, more preferably 0.10 mmol:0.25 mL.

[0278] In this invention, the preferred method for mixing the actinaphthoran B, iso-maleimide, and the first solvent is to degas the mixture with argon gas for 10–30 minutes. This invention does not impose any special limitations on the flow rate or amount of argon gas; any technical solution well-known to those skilled in the art can be used.

[0279] In this invention, the power of the mercury lamp is preferably 400-500W, more preferably 450W; the maximum wavelength of the mercury lamp is preferably 365nm.

[0280] In this invention, the preferred temperature for the Diels-Alder reaction is room temperature; the preferred reaction time is 45–50 h, more preferably 48 h. By controlling the amount of each raw material, the reaction temperature, and the reaction time within the above ranges, this invention ensures that the reaction proceeds fully.

[0281] After the Diels-Alder reaction is completed, the product of the Diels-Alder reaction is preferably subjected to vacuum distillation, rapid chromatography purification and preparative TLC separation in sequence to obtain compound A and compound B.

[0282] In this invention, the structural formula of compound A is as follows:

[0283] In this invention, the structural formula of compound B is as follows:

[0284] The present invention does not impose any special limitations on the operation of vacuum distillation, rapid chromatography purification and preparative TLC separation, and any technical solutions known to those skilled in the art can be used.

[0285] In one embodiment, after obtaining compound B, the present invention mixes compound B, a second solvent, and silica gel to carry out a cyclization reaction to obtain Lugdunomycin.

[0286] In this invention, the second solvent is preferably methanol.

[0287] In this invention, the preferred molar ratio of compound B to the volume ratio of the second solvent is 0.032 mmol:(0.5-1.5) mL, more preferably 0.032 mmol:1 mL.

[0288] In this invention, the mass ratio of compound B to silica gel is preferably 1:(1-3), more preferably 1:2.

[0289] In this invention, the preferred method for mixing compound B, the second solvent, and silica gel is to mix compound B and the second solvent, and then add silica gel at 8–12°C.

[0290] In this invention, the preferred temperature for the cyclization reaction is 5–15°C, more preferably 10°C; the preferred time for the cyclization reaction is 46–50 h, more preferably 48 h; and the cyclization reaction is preferably carried out under stirring conditions. This invention does not impose any particular limitation on the stirring method and rate; any technical solution well-known to those skilled in the art can be used. By controlling the amount of each raw material, the reaction temperature, and the time within the above-mentioned ranges, this invention ensures that the reaction proceeds fully.

[0291] After the cyclization reaction is completed, the product of the cyclization reaction is preferably subjected to vacuum distillation and preparative TLC separation in sequence to obtain Lugdunomycin.

[0292] In this invention, the structural formula of the Lugdunomycin is as follows:

[0293] The present invention does not impose any special limitations on the operation of vacuum distillation and preparative TLC separation; any technical solution known to those skilled in the art can be used.

[0294] In one embodiment, after obtaining compound A, the present invention mixes compound A, iso-maleimide, and a third solvent, and performs a Diels-Alder reaction under mercury lamp irradiation to obtain compound B. Then, compound B, a second solvent, and silica gel are mixed and subjected to a cyclization reaction to obtain lugdunomycin.

[0295] In this invention, compound A, iso-maleimide, and a third solvent are mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to obtain compound B. The preferred reaction conditions are the same as those for compound A and compound B, and will not be repeated here.

[0296] In this invention, the reaction conditions for mixing compound B, the second solvent, and silica gel to carry out a cyclization reaction to obtain Lugdunomycin are preferably the same as those for mixing compound B, the second solvent, and silica gel to carry out a cyclization reaction to obtain Lugdunomycin, and will not be repeated here.

[0297] This invention prepares Lugdunomycin by reacting the compound actinaphthoran B with iso-maleimide via an intermolecular photoinduced asymmetric Diels-Alder reaction. The synthesis method is simple, the conditions are mild, the raw materials are readily available, and the cost is low, thus making up for the deficiencies of natural Lugdunomycin and meeting people's demand for Lugdunomycin.

[0298] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0299] Example 1

[0300] A method for preparing Lugdunomycin comprises the following steps:

[0301] (1) 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester (compound C, 25.00 g, 124.95 mmol, 1.0 eq) and 500 mL of methanol (the molar ratio of 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester to the volume ratio of methanol was 124.95 mmol: 500 mL) were mixed, and sodium borohydride (2.37 g, 62.48 mmol, 0.5 eq) was slowly added at 0 °C. The mixture was prepared by stirring at 0°C for 1 h with 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester and sodium borohydride in a molar ratio of 1:0.5. The mixture was quenched with 1 mol / L hydrochloric acid (400 mL), extracted with ethyl acetate (3 times, 500 mL each time), and the combined organic layers were dried with sodium sulfate and then rotary evaporated to give a colorless oily intermediate 1 (22.73 g, 90%) with sufficient purity for the next step of the reaction.

[0302] Intermediate product 1 (22.73 g, 112.52 mmol, 1.0 eq) and N,N-diisopropylethylamine (17.45 g, 23.52 mL, 135.02 mmol, 1.2 eq) were dissolved in dichloromethane (700 mL). Triisopropyltrifluoromethanesulfonate (36.20 g, 32.41 mL, 118.15 mmol, 1.05 eq) was slowly added at -78 °C, and the mixture was stirred at -78 °C for 1.5 h. The reaction was then quenched with saturated ammonium chloride aqueous solution (200 mL), extracted with dichloromethane (300 mL each time), and the combined organic layers were dried with sodium sulfate and then subjected to rotary evaporation. The mixture was purified by column chromatography (silica gel, a mixture of ethyl acetate and n-hexane in a volume ratio of 1:20) to give a colorless oily silyl ether (36.67 g, 91%).

[0303] The obtained silyl ether (36.67 g, 102.36 mmol, 1.0 eq) was mixed with tetrahydrofuran (600 mL) to obtain mixture A. Diisopropylaminolithium was mixed with tetrahydrofuran to obtain mixture B. Mixture B (the concentration of diisopropylaminolithium in mixture B was 2 mol / L, and the amount of diisopropylaminolithium used was 204.72 mmol, 2.0 eq) was added dropwise to mixture A. The mixture was stirred at the same temperature (-78 °C) for 1 h, and then I2 was added. (25.98 g, 102.36 mmol, 1.0 eq) was stirred at -78 °C for 2 h, then quenched with saturated Na2SO3 aqueous solution (100 mL), extracted with dichloromethane (extracted 3 times, 200 mL each time), the combined organic layers were dried with Na2SO4, and then purified by column chromatography (silica gel, a mixture of ethyl acetate and n-hexane in a volume ratio of 1:15) after rotary evaporation to give a pale yellow oily compound D (28.44 g, 78%).

[0304] (2) At 0 °C, compound D (5.00 g, 14.04 mmol, 1.0 eq) and methanol (100 mL) were mixed and NaOH (3.37 g, 84.22 mmol, 6.0 eq) was added. The mixture was stirred at room temperature for 4 h, then quenched with 1 mol / L HCl (85 mL) and extracted with dichloromethane (200 mL each time). The combined organic layers were dried with NaSO4 and then rotary evaporated to obtain a colorless oily crude acid (4.05 g, 88%) with sufficient purity for the next step.

[0305] Crude acid (4.05 g, 12.34 mmol, 1.0 eq) and acetic anhydride (10 mL) were mixed and stirred at room temperature for 16 h. The solvent was removed by rotary evaporation to obtain a brown oily substance. The solution was cooled in an ice bath and concentrated ammonium hydroxide (10 mL, 28% by mass) was slowly added. The mixture was stirred for 10 min. The resulting solution was acidified to pH 6.0 by slowly adding 1.0 mol / L hydrochloric acid. The separated white solid was washed with water and dried to obtain crude imide (3.84 g, 95%).

[0306] Crude imide (3.84 g, 11.74 mmol, 1.0 eq) and trifluoroacetic anhydride (30 mL) were mixed and stirred at 40 °C for 16 h. The solvent was removed under reduced pressure to obtain the crude product, which was purified by column chromatography (silica gel, a mixture of ethyl acetate and n-hexane in a volume ratio of 1:15) to give colorless oily compound E (2.28 g, 63%).

[0307] (3) Compound E (2.00 g, 6.47 mmol, 1.0 eq) and tetrahydrofuran (60 mL) were mixed to obtain mixture A. Tetrabutylammonium fluoride and tetrahydrofuran were mixed to obtain mixture B (the concentration of tetrabutylammonium fluoride in mixture B was 1 mol / L, and the amount of tetrabutylammonium fluoride was 9.7 mmol, 1.5 eq). Then mixture B was added to mixture A, stirred at room temperature for 2 h, quenched with saturated NH4Cl aqueous solution (10 mL), and extracted with ethyl acetate (3 times, 60 mL each time). The combined organic layers were dried with NaSO4, and the solvent was removed by rotary evaporation. The mixture was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio of 4:1) to obtain the white solid compound isomaleimide (792 mg, 80%).

[0308] (4) 2-hydroxy-4-methyl-3'-methoxybiphenyl (compound L, 15.00 g, 79.75 mmol, 1.0 eq) and tetrahydrofuran (500 mL) were mixed, and NaH (4.79 g, 119.63 mmol, 0.5 eq) was slowly added at 0 °C. The mixture was stirred at room temperature for 0.5 h, and then iodomethane (3.00 g, 15.66 mmol, 1.1 eq) was added at 0 °C. After 8 h, the mixture was quenched with saturated NH4Cl aqueous solution (100 mL), extracted with diethyl ether (3 times, 100 mL each time), and the combined organic layers were dried with NaSO4. The solvent was removed by rotary evaporation of the filtrate to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:50) to obtain colorless solid compound M (15.80 g, 98%).

[0309] (5) Compound M (8.00 g, 39.58 mmol, 1.0 eq) and benzene (300 mL) were mixed to obtain mixture A. Tert-butyllithium and pentane were mixed to obtain mixture B (the concentration of tert-butyllithium in mixture B was 1.3 mol / L, and the amount of tert-butyllithium used was 39.58 mmol, 1.0 eq). Mixture B was slowly added to mixture A at 0 °C and stirred at room temperature for 18 h. Then, N,N-dimethylformamide was added at 0 °C. 3.18 g, 3.37 mL, 43.54 mmol, 1.1 eq) were stirred at room temperature for 2 h, quenched with saturated NH4Cl (100 mL) aqueous solution, extracted with diethyl ether (3 times, 100 mL each time), the combined organic layers were dried with NaSO4, and the filtrate was then rotary evaporated to remove the solvent to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:30) to give colorless oily compound O (4.92 g, 54%).

[0310] (6) Compound O (4.50 g, 19.56 mmol, 1.0 eq) and dichloromethane (100 mL) were mixed, and boron tribromide (14.70 g, 5.65 mL, 58.67 mmol, 3.0 eq) was slowly added at 0 °C. The mixture was stirred at 0 °C for 2 h, and the reaction was quenched with water (20 mL). The mixture was extracted with ethyl acetate (3 times, 100 mL each time). The combined organic layers were dried with NaSO4, and the solvent was removed by rotary evaporation of the filtrate to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate, n-hexane and methanol volume ratio 5:10:1) to obtain yellow solid compound I (3.48 g, 88%).

[0311] (7) 2-Bromo-6-methoxybenzoic acid (compound F, 10.00 g, 43.49 mmol, 1.0 eq) and tetrahydrofuran (300 mL) were mixed to obtain mixture A. Borane methyl sulfide and DMS were mixed to obtain mixture B (the concentration of borane methyl sulfide in mixture B was 10.0 mol / L, and the amount of borane methyl sulfide was 86.97 mmol, 2.0 eq). Mixture B was slowly added to mixture A at 0 °C and stirred at 60 °C for 6 h. The reaction was quenched with methanol (20 mL) at 0 °C. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:4) to obtain colorless oily compound G (8.92 g, 95%).

[0312] (8) Compound G (7.60 g, 35.19 mmol, 1.0 eq) and N,N-diisopropylethylamine (5.46 g, 7.35 mL, 42.23 mmol, 2.2 eq) were dissolved in dichloromethane (200 mL), and chloromethyl ether (3.12 g, 2.94 mL, 38.71 mmol, 3.1 eq) was slowly added at room temperature. The mixture was stirred at room temperature for 16 h, then quenched with saturated NH4Cl aqueous solution (50 mL) and extracted with dichloromethane (3 times, 100 mL each time). The combined organic layers were dried with NaSO4, and the filtrate was then evaporated to remove the solvent to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:10) to obtain colorless oily compound H.

[0313] (9) Compound H (4.50 g, 17.31 mmol, 3.0 eq) and tetrahydrofuran (200 mL) were mixed to obtain mixture A. Butyllithium and pentane were mixed to obtain mixture B (the concentration of n-butyllithium in mixture B was 1.6 mol / L, and the amount of n-butyllithium used was 17.30 mmol, 1.0 eq). Mixture B was slowly added to mixture A at -78 °C, and the mixture was stirred at -78 °C for 45 min. Then, the compound H was added at -78 °C. Compound I (1.17 g, 5.77 mmol, 1.0 eq) was stirred at -78 °C for 1 h, and the reaction was quenched with saturated NH4Cl (100 mL) aqueous solution. The mixture was extracted with ethyl acetate (3 times, 100 mL each time), and the combined organic layers were dried with NaSO4. The solvent was then removed by rotary evaporation of the filtrate to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:2) to give colorless oily compound J (1.57 g, 71%).

[0314] (10) Compound J (1.10 g, 2.86 mmol, 1.0 eq) was mixed with dichloromethane (300 mL), and trifluoroacetic acid (653 mg, 0.44 mL, 5.73 mmol, 2.0 eq) was slowly added at 0 °C. The mixture was stirred at 0 °C for 1 h, and the reaction was quenched with saturated NaHCO3 aqueous solution (50 mL). The mixture was extracted with dichloromethane (3 times, 100 mL each time), and the organic layers were combined and the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:8) to obtain compound K (608 mg, 58%) as a white solid.

[0315] (11) Compound K (530 mg, 1.45 mmol, 1.0 eq) and tetrahydrofuran (40 mL) were mixed, and HCl (5.0 mol / L, 10 mL) was added at room temperature. The mixture was stirred at 40 °C for 16 h, and the reaction was quenched with saturated NaHCO3 aqueous solution (100 mL). The mixture was extracted with dichloromethane (3 times, 100 mL each time), and the organic layers were combined and the solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:6) to obtain actinaphthoran A (326 mg, 70%) as a white solid.

[0316] (12) Compound actinaphthoran A (120 mg, 0.37 mmol, 1.0 eq) and sulfur trioxide pyridine complex (118 mg, 0.74 mmol, 2.0 eq) were mixed with dimethyl sulfoxide (8 mL), and triethylamine (113 mg, 155 μL, 1.12 mmol, 3.0 eq) was added at room temperature. The mixture was stirred at room temperature for 2 h, then quenched with saturated NH4Cl aqueous solution (5 mL) and extracted with diethyl ether (3 times, 20 mL each time). The combined organic layers were dried with NaSO4, and the filtrate was then evaporated to remove the solvent to obtain the crude product. The crude product was purified by column chromatography (silica gel, ethyl acetate and n-hexane volume ratio 1:10) to obtain the yellow solid compound actinaphthoran B (54 mg, 45%).

[0317] (13) Compound actinaphthoran B (32 mg, 0.10 mmol, 1.0 eq) and compound iso-maleimide (61 mg, 0.40 mmol, 4.0 eq) were dissolved in dimethyl sulfoxide (0.25 mL), degassed with an argon stream for 20 min, and then irradiated with a 450 W, 365 nm mercury lamp at room temperature for 48 h. The solvent was removed under reduced pressure to obtain the crude product. The crude product was purified by rapid chromatography to obtain a mixture of compound A and compound B, which were then separated by preparative TLC to obtain compound A (13 mg, 41%) and compound B (19 mg, 40%) in the form of yellow solid and white solid, respectively.

[0318] (14) Compound B (15 mg, 0.032 mmol, 1.0 eq) was mixed with methanol (1 mL), silica gel (30 mg) was added at 10 °C, and the mixture was stirred at 10 °C for 48 h. The solvent was removed under reduced pressure to obtain the crude product. The crude product was separated by preparative TLC to obtain the white solid compound Lugdunomycin (9 mg, 60%).

[0319] Example 1 Step (1) The reaction formula for preparing compound D from compound C is as follows: Figure 1 As shown. The 1H NMR spectrum of compound D prepared in step (1) of Example 1 is shown below. Figure 2 As shown, the carbon NMR spectrum is as follows: Figure 3 As shown; the NMR data are:

[0320] 1 H NMR (300MHz, CDCl3) δ4.73-4.56 (m, 1H), 3.77 (s, 6H), 3.06-2.91 (m, 2H), 2.81-2.63 (m, 2H), 1.08-0.97 (m, 24H). 13 C NMR (75MHz, CDCl3) δ165.6, 137.3, 70.6, 52.0, 44.6, 17.8, 11.9.

[0321] Example 1, step (2): The reaction formula for preparing compound E from compound D is as follows. Figure 4 As shown. The 1H NMR spectrum of compound E prepared in step (2) of Example 1 is shown below. Figure 5 As shown, the carbon NMR spectrum is as follows: Figure 6 As shown; the NMR data are:

[0322] 1H NMR (400MHz, CDCl3) δ7.08 (s, 1H), 5.13-4.97 (m, 1H), 3.04-2.91 (m, 2H), 2.71-2.56 (m, 2H), 1.10-1.01 (m, 24H). 13 C NMR (100MHz, CDCl3) δ166.7, 151.2, 76.4, 37.7, 17.8, 11.8.

[0323] Example 1, step (3): The reaction formula for preparing compound iso-maleimide from compound E is as follows. Figure 7 As shown. The 1H NMR spectrum of the compound iso-maleimide prepared in step (3) of Example 1 is shown below. Figure 8 As shown, the carbon NMR spectrum is as follows: Figure 9 As shown; the NMR data are:

[0324] 1 H NMR (400MHz, Methanol-d4) δ 4.94-4.88 (m, 1H), 3.79-3.66 (m, 1H), 2.98-2.83 (m, 2H), 2.52-2.41 (m, 2H), 1.89-1.78 (m, 1H). 13 C NMR (100MHz, Methanol-d4) δ168.3, 151.2, 75.3, 67.4, 35.8, 25.0.

[0325] Example 1, step (4): The reaction formula for preparing compound M from compound L is as follows. Figure 10 As shown. The 1H NMR spectrum of compound M prepared in step (4) of Example 1 is shown below. Figure 11 As shown, the carbon NMR spectrum is as follows: Figure 12 As shown; the NMR data are:

[0326] 1 H NMR (400MHz, CDCl3) δ7.62 (d, J=8.9Hz, 1H), 7.50 (d, J=2.6Hz, 1H), 7.16 (q, J=1.2Hz, 1H), 7.13 (dd, J=8.9, 2.6Hz, 1H), 6.66 (d, J=1.5Hz, 1H), 4.00 (s, 3H), 3.94 (s, 3H), 2.48 (d, J=1.0Hz, 3H).

[0327] 13C NMR (100MHz, CDCl3) δ156.7, 154.3, 133.0, 129.9, 128.3, 124.5, 119.0 (2C), 106.6, 100.1, 55.4, 55.2, 21.9.

[0328] Example 1, step (5): The reaction formula for preparing compound O from compound M is as follows. Figure 13 As shown. The 1H NMR spectrum of compound O prepared in step (5) of Example 1 is shown below. Figure 14 As shown, the carbon NMR spectrum is as follows: Figure 15 As shown; the NMR data are:

[0329] 1 H NMR (400MHz, CDCl3) δ10.73 (s, 1H), 7.76 (d, J = 9.1Hz, 1H), 7.25 (d, J = 9.8Hz, 1 H), 7.18 (s, 1H), 6.69 (d, J=0.9Hz, 1H), 3.91 (s, 3H), 3.91 (s, 3H), 2.46 (s, 3H).

[0330] 13 C NMR (100MHz, CDCl3) δ195.0, 154.6, 153.9, 134.2, 131.1, 130.1, 122.1, 121.7, 119.9, 114.2, 108.8, 57.0, 55.7, 21.7.

[0331] Example 1, step (6): The reaction formula for preparing compound I from compound O is as follows. Figure 16 As shown. The 1H NMR spectrum of compound I prepared in step (6) of Example 1 is shown below. Figure 17 As shown, the carbon NMR spectrum is as follows: Figure 18 As shown; the NMR data are:

[0332] 1 H NMR (500MHz, DMSO) δ 13.79 (s, 1H), 11.25 (s, 1H), 10.69 (s, 1H), 7.99 (d, J=9.1Hz, 1H), 7.18 (s, 1H), 7.09 (d, J=9.0Hz, 1H), 6.94 (s, 1H), 2.33 (s, 3H). 13 C NMR (125MHz, DMSO) δ199.8, 164.8, 153.6, 139.6, 134.5, 130.6, 120.8, 120.0, 119.6, 116.3, 113.9, 21.2.

[0333] Example 1, step (7): The reaction formula for preparing compound G from compound F is as follows. Figure 19 As shown. The 1H NMR spectrum of compound G prepared in step (7) of Example 1 is shown below. Figure 20 As shown, the carbon NMR spectrum is as follows: Figure 21 As shown; the NMR data are:

[0334] 1 H NMR (500MHz, CDCl3) δ7.16-7.12 (m, 1H), 7.12-7.04 (m, 1H), 6.81 (dd, J=8.1, 0.7Hz, 1H), 4.84 (s, 2H), 3.82 (s, 3H), 2.67 (s, 1H).

[0335] 13 C NMR (125MHz, CDCl3) δ158.9, 130.0, 128.5, 125.2, 125.1, 110.0, 60.3, 56.0.

[0336] Example 1, step (8): The reaction formula for preparing compound H from compound G is as follows. Figure 22 As shown. The 1H NMR spectrum of compound H prepared in step (8) of Example 1 is shown below. Figure 23 As shown, the carbon NMR spectrum is as follows: Figure 24 As shown; the NMR data are:

[0337] 1 H NMR (500MHz, CDCl3) δ7.21-7.17 (m, 1H), 7.17-7.10 (m, 1H), 6.85 (dd, J=8.1, 0.8Hz, 1H), 4.79 (s, 2H), 4.75 (s, 2H), 3.85 (s, 3H), 3.45 (s, 3H).

[0338] 13 C NMR (125MHz, CDCl3) δ159.5, 130.4, 126.9, 125.9, 125.1, 110.1, 96.4, 63.5, 56.2, 55.5.

[0339] Example 1, step (9): The reaction formula for preparing compound J from compound H is as follows. Figure 25 As shown. The 1H NMR spectrum of compound J prepared in step (9) of Example 1 is shown below. Figure 26 As shown, the carbon NMR spectrum is as follows: Figure 27 As shown; the NMR data are:

[0340] 1H NMR (400MHz, Methanol-d4) δ7.73 (s, 1H), 7.57 (d, J=8.9Hz, 1H), 7.06 (s, 1H), 7.04-7.01 (m, 2H), 6.88 (d, J=8.1Hz, 1H), 6.58 (d, J= 1.6Hz, 1H), 6.56 (d, J=7.8Hz, 1H), 5.05 (dd, J=96.8, 10.6Hz, 2H), 4.78 (s, 3H), 4.61 (s, 1H), 3.83 (s, 3H), 3.47 (s, 3H), 2.31 (s, 3H).

[0341] 13 C NMR (100MHz, Methanol-d4) δ158.6, 153.4, 152.4, 143.4, 132.5, 131.8, 129.0, 128.4, 124 .3, 122.1, 120.4, 119.5, 118.3, 117.2, 113.4, 110.0, 95.8, 69.5, 60.3, 54.9, 54.3, 19.6.

[0342] Example 1, step (10): The reaction formula for preparing compound K from compound J is as follows. Figure 28 As shown. The 1H NMR spectrum of compound K prepared in step (10) of Example 1 is shown below. Figure 29 As shown, the carbon NMR spectrum is as follows: Figure 30 As shown; the NMR data are:

[0343] 1 H NMR (400MHz, DMSO-d6) δ9.56 (s, 1H), 7.51 (d, J=8.0Hz, 1H), 7.27 (s, 1H), 7.19 (t, J=8.0Hz, 1H), 7.06 (d, J=8.6Hz, 1H), 7.00 (d, J=7.6 Hz, 1H), 6.98 (s, 1H), 6.47-6.41 (m, 2H), 4.87 (dd, J=26.0, 10.7Hz, 2H), 4.65 (q, J=6.5Hz, 2H), 3.81 (s, 3H), 3.31 (s, 3H), 2.37 (s, 3H).

[0344] 13C NMR (100MHz, DMSO-d6) δ159.5, 158.3, 147.6, 139.1, 136.1, 129.9, 128.8, 125.9, 125.3 , 124.2, 121.3, 120.8, 119.3, 114.8, 111.7, 102.5, 95.8, 86.0, 59.3, 56.3, 55.2, 22.7.

[0345] Example 1 Step (11) The reaction formula for preparing compound actinaphthoran A from compound K is as follows: Figure 31 As shown. The 1H NMR spectrum of the compound actinaphthoran A prepared in step (11) of Example 1 is shown below. Figure 32 As shown, the carbon NMR spectrum is as follows: Figure 33 As shown; the NMR data are:

[0346] 1 H NMR (300MHz, DMSO-d6) δ9.71 (s, 1H), 7.48 (d, J = 8.6Hz, 1H), 7.34 (s, 1H), 7.15 (t, J = 8.0Hz, 1H), 7.02-6.90 (m, 3H), 6.49 (s, 1H), 6.46 (d, J=7.8Hz, 1H), 5.96 (s, 1H), 4.92 (dd, J=54.6, 9.7Hz, 2H), 3.80 (s, 3H), 2.38 (s, 3H).

[0347] 13 C NMR (75MHz, DMSO-d6) δ159.8, 157.2, 147.1, 139.4, 136.1, 129.5, 128.3, 126.4, 126.0, 125.4, 121.5, 121.3, 119.0, 114.9, 111.3, 102.4, 85.3, 56.2, 53.6, 22.7.

[0348] Example 1, step (12): The reaction formula for preparing compound actinaphthoran B from compound actinaphthoran A is as follows. Figure 34 As shown. The 1H NMR spectrum of the compound actinaphthoran B prepared in step (12) of Example 1 is shown below. Figure 35 As shown, the carbon NMR spectrum is as follows: Figure 36 As shown; the NMR data are:

[0349] 1H NMR (300MHz, CDCl3) δ10.66 (s, 1H), 7.93 (s, 1H), 7.53-7.39 (m, 2H), 7.17 (s, 1H), 7.11-6.98 (m, 3H), 6.91 (d, J=8.3Hz, 1H), 6.59 (s, 1H), 3.95 (s, 3H), 2.49 (s, 3H).

[0350] 13 C NMR (75MHz, CDCl3) δ197.6, 162.0, 159.8, 146.8, 141.9, 136.5, 136.5, 127.3, 12 6.7, 125.4, 122.7, 121.3, 121.1, 119.2, 115.3, 110.6, 102.6, 84.8, 56.0, 22.6.

[0351] Example 1, step (13): The reaction formula for preparing compounds A and B from compound actinaphthoran B is as follows. Figure 37 As shown. The 1H NMR spectrum of compound A prepared in step (13) of Example 1 is shown below. Figure 38 As shown, the carbon NMR spectrum is as follows: Figure 39 As shown; the NMR data are:

[0352] 1 H NMR (400MHz, DMSO) δ9.78 (s, 1H), 7.64 (d, J = 8.6Hz, 1H), 7.28 (t, J = 7.8Hz, 1H), 7.11 (d, J = 8.6Hz, 1H), 7.08 -6.96 (m, 2H), 6.52 (d, J=7.5Hz, 1H), 6.46 (s, 1H), 5.23 (dd, J=43.0, 13.1Hz, 2H), 3.88 (s, 3H), 2.39 (s, 3H).

[0353] 13 C NMR (100MHz, DMSO) δ155.7, 153.9, 150.3, 139.4, 135.8, 130.6, 127.8, 127.8, 12 7.1, 124.9, 123.1, 121.5, 116.5, 115.3, 114.7, 111.8, 103.3, 71.2, 55.9, 22.7.

[0354] The proton NMR spectrum of compound B prepared in step (13) of Example 1 is shown below. Figure 40 As shown, the carbon NMR spectrum is as follows: Figure 41 As shown; the NMR data are:

[0355] 1 H NMR (400MHz, Methanol-d4) δ7.62 (d, J=8.9Hz, 1H), 7.34 (dd, J=8.3, 7.4Hz, 1H), 7.11 (d, J=8.8Hz, 1H), 7.09 (d, J=1.7Hz, 1H), 7.07 (dd, J=7.4, 0.6Hz, 1H), 7.02 (dd, J=8.4, 0.7Hz, 1H), 6.61 (d, J=1. 9Hz, 1H), 5.85 (s, 1H), 4.10 (t, J=3.4Hz, 1H), 3.96 (s, 3H), 2.47 (dd, J=15.1, 2.3Hz, 1H), 2.33-2.2 4 (m, 3H), 2.06 (dd, J=14.0, 2.2Hz, 1H), 1.45 (dd, J=15.0, 3.7Hz, 1H), 1.16 (dd, J=13.9, 3.5Hz, 1H).

[0356] 13 C NMR (100MHz, Methanol-d4) δ181.8, 178.5, 154.8, 154.6, 151.0, 145.6, 132.3, 132.0, 131.1, 129.9, 127. 0, 122.7, 120.5, 117.5, 116.4, 116.2, 110.4, 109.0, 98.5, 80.1, 77.5, 71.7, 68.0, 54.8, 44.4, 37.4, 19.2.

[0357] Example 1, step (14), reaction formula for the preparation of Lugdunomycin from compound B is as follows: Figure 42 As shown. The 1H NMR spectrum of Lugdunomycin prepared in step (14) of Example 1 is shown below. Figure 43 As shown, the carbon NMR spectrum is as follows: Figure 44 As shown; the NMR data are:

[0358] 1 H NMR (600MHz, Methanol-d4) δ7.39 (d, J=8.5Hz, 1H), 7.21 (t, J=8.1Hz, 1H), 6.95 (dd, J=5.4,

[0359] 1.1Hz, 1H), 6.94 (d, J=1.1Hz, 1H), 6.90 (dd, J=8.2, 0.9Hz, 1H), 6.77 (d, J=8.5Hz, 1H), 6.55 (d, J=1.0Hz, 1H), 5.62 (s, 1H), 4. 07 (s, 1H), 3.88 (s, 3H), 2.64-2.59 (m, 2H), 2.44 (d, J=0.9Hz, 3H), 2.38 (dd, J=14.6, 3.7Hz, 1H), 1.60 (dd, J=13.7, 3.7Hz, 1H).

[0360] 13 C NMR (100MHz, Methanol-d4) δ182.4, 182.3, 158.9, 158.4, 147.9, 139.2, 136.4, 131.0, 129.1, 127.6, 127. 1, 123.7, 123.1, 122.4, 119.8, 115.7, 111.1, 102.5, 94.8, 70.5, 62.5, 62.3, 59.7, 56.1, 47.9, 47.4, 22.1.

[0361] In summary, this invention prepares Lugdunomycin through a chemical reaction, which makes up for the deficiencies of natural Lugdunomycin and thus meets people's demand for Lugdunomycin.

[0362] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing Lugdunomycin, comprising the following steps: (1) Add actinaphthoran B, iso -maleimide and the first solvent were mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to give compound A and compound B; The structural formula of compound A is as follows: The structural formula of compound B is as follows: The iso The structure of -maleimide is ; (2) The compound B obtained in step (1), the second solvent and silica gel are mixed and subjected to a cyclization reaction to obtain Lugdunomycin; Alternatively: (2) the compound A obtained in step (1), iso -maleimide and a third solvent are mixed and subjected to a Diels-Alder reaction under mercury lamp irradiation to obtain compound B. Then, compound B, a second solvent, and silica gel are mixed and subjected to a cyclization reaction to obtain Lugdunomycin. The mercury lamp has a power of 400~500W and a maximum wavelength of 365nm; The Diels-Alder reaction is carried out at a temperature of 20-30°C; the cyclization reaction is carried out at a temperature of 5-15°C.

2. The preparation method according to claim 1, characterized in that, In step (1), actinaphthoran B and iso The molar ratio of -maleimide is 1:(3~5).

3. The preparation method according to claim 1, characterized in that, The first solvent in step (1) is at least one of toluene, 1,4-dioxane and dimethyl sulfoxide.

4. The preparation method according to claim 1, characterized in that, The Diels-Alder reaction time in step (1) is 46-50 h.

5. The preparation method according to claim 1, characterized in that, In step (1) iso The preparation method of -maleimide includes the following steps: 1) A reduction reaction was carried out by mixing 4-carbonyl-cyclopentane-trans-1,2-dicarboxylic acid dimethyl ester, a reducing agent, and a solvent to obtain intermediate product 1; 2) The intermediate product 1 obtained in step 1) is mixed with triisopropyltrifluoromethanesulfonate, N,N-diisopropylethylamine and solvent, and hydroxyl groups are protected to obtain silyl ether; 3) The silicon ether obtained in step 2) is mixed with diisopropylaminolithium, I2 and a solvent, and reacted at low temperature to obtain compound D; the structural formula of compound D is as follows: ; 4) The compound D obtained in step 3) is mixed with a base and a solvent and subjected to a hydrolysis reaction to obtain crude acid; 5) The crude acid obtained in step 4) is mixed with acetic anhydride and ammonium hydroxide to carry out a monoamidation reaction to obtain crude imide; 6) The crude imide obtained in step 5) is mixed with trifluoroacetic anhydride and subjected to a cyclization reaction to obtain compound E; the structural formula of compound E is as follows: ; 7) The compound E obtained in step 6) is mixed with tetrabutylammonium fluoride and a solvent to perform deprotection, yielding... iso -maleimide.

6. The preparation method according to claim 1, characterized in that, The preparation method of actinaphthoran B in step (1) includes the following steps: a. 2-Bromo-6-methoxybenzoic acid is mixed with boron methyl sulfide and a solvent to undergo a reduction reaction to obtain compound G; the structural formula of compound G is as follows: ; b. The compound G obtained in step a is mixed with chloromethyl ether, N,N-diisopropylethylamine and a solvent to protect the hydroxyl groups, yielding compound H; the structural formula of compound H is as follows: ; c. The compound H obtained in step b is mixed with n-butyllithium, a solvent, and compound I to undergo an addition reaction to obtain compound J; the structural formula of compound I is [insert structural formula here]. The structural formula of compound J is as follows: ; d. Compound J obtained in step c is mixed with trifluoroacetic acid and a solvent to undergo a cyclization reaction to obtain compound K; the structural formula of compound K is as follows: ; e. The compound K obtained in step d is mixed with hydrochloric acid and a solvent to perform deprotection, yielding compound actinaphthoran A; the structural formula of compound actinaphthoran A is as follows: ; f. The compound actinaphthoran A obtained in step e is mixed with a sulfur trioxide pyridine complex, triethylamine, and a solvent, and subjected to an oxidation reaction to obtain actinaphthoran B; the structural formula of actinaphthoran B is as follows: .

7. The preparation method according to claim 6, characterized in that, The preparation method of compound I in step c includes the following steps: ① A substitution reaction was carried out by mixing 2-hydroxy-4-methyl-3'-methoxybiphenyl with sodium hydride, iodomethane, and a solvent to obtain compound M; the structural formula of compound M is as follows: ; ② The compound M obtained in step ① is mixed with tert-butyllithium, N,N-dimethylformamide and a solvent to undergo a formylation reaction to obtain compound O; the structural formula of compound O is as follows: ; ③ The compound O obtained in step ② is mixed with boron tribromide and a solvent to remove protection, thereby obtaining compound I.

8. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of compound B to silica gel is 1:(1~3).

9. The preparation method according to claim 1, characterized in that, The cyclization reaction in step (2) takes 46-50 hours.

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