Environment-friendly synthesis method of cordycepin by taking inosine as raw material

Abstract

The invention relates to the technical field of fine chemical engineering, and discloses a preparation method of cordycepin, which comprises the following steps: with inosine as a raw material, firstly protecting 2 ', 3' hydroxyl groups, then protecting 5 'hydroxyl groups, then halogenating C-3' of a furan ring, then carrying out chlorination reaction on a purine ring, and finally carrying out dehalogenation reaction on the C-3 'to obtain the cordycepin. And carrying out ammonification reaction and hydroxyl deprotection reaction to obtain cordycepin. The raw materials used in the synthesis route are cheap and easy to obtain, no metal catalyst is used, the cost is reduced, and the synthesis route is more environment-friendly; and the synthesis process is simple, easy to operate, relatively high in yield and beneficial to industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of fine chemical industry, and in particular to a more environmentally friendly method for preparing cordycepin using inosine as a raw material. Background Art

[0002] Cordycepin, also known as cordycepin, cordycepin, and pupae cordycepin, is also known as 3'-deoxyadenosine (3'-deoxy-adenosin, hereinafter referred to as 3'-dA). It is a nitrogen-containing glycoside nucleic acid binding organism - purine alkaloids; the N-glycosidic bond of 3'-dA is relatively stable, but under severe hydrolysis conditions (pH <1), the N-glycosidic bond will break to form adenine. Its main function is to inhibit the phosphorylation of nucleosides or nucleotides to generate diphosphate and triphosphate derivatives, thereby inhibiting the synthesis of tumor cell nucleic acids.

[0003] Cordycepin has a wide range of pharmacological activities, including vasodilation, lowering blood pressure, slowing heart rate, stimulating adrenaline, generating steroid hormones, inhibiting platelet aggregation, sedation, anticonvulsant, anti-oxidation, anti-inflammatory and anti-tumor, etc. It has a good prospect in the fields of beauty and anti-aging, health products, medicine and scientific research, and has become a current research hotspot. However, natural cordyceps resources are scarce, the cordycepin content is very low, the price is expensive, the extraction process is cumbersome and the loss is serious, so it is difficult to extract cordycepin directly from natural cordyceps as a raw material, and in 2001, Cordyceps sinensis was included in the list of national second-level protected plants, so it can only be replaced by artificial synthesis.

[0004] Existing cordycepin synthesis routes:

[0005] Route 1:

[0006]

[0007] This method uses D-xylose as the starting material, condenses with acetone to form a ring to protect the hydroxyl group, then uses hydrochloric acid for selective deprotection, reacts with benzoyl chloride to selectively protect C-5'-OH, and then reacts with thiochloroformic acid-O-phenyl ester to obtain 5-O-benzoyl-3-O-thiobenzoyl-1,2-O-isopropylidene-α-D-xylose. Then catalytic deoxygenation, ring opening and acylation reactions are carried out, followed by glycosylation reaction, and finally deprotection in a saturated methanol solution of ammonia to obtain cordycepin. The total yield of this route is 30-50%, the overall synthetic route is long, the metal catalyst used in the synthesis has a large environmental pollution, the operation is cumbersome, and it is not conducive to industrial production.

[0008] Route 2:

[0009]

[0010] This method uses adenosine as a raw material, first selectively protects C-5'-OH to obtain 5'-O-trityladenosine, then selectively protects C-3'-OH to obtain 3'-O-p-methylbenzenesulfonyl-5'-O-trityladenosine, and then reduces to obtain 5'-O-trityladenosine-3'-deoxyadenosine, and finally deprotects under acidic conditions to obtain cordycepin. The total yield of this route does not exceed 40%, the yield is low, the reagents are relatively expensive, and the use of metal reducing agents leads to greater pollution, which is not suitable for industrial production.

[0011] In summary, the existing cordycepin synthesis process has many by-products, which are difficult to separate and purify, resulting in low yields and other problems, and excessive use of toxic and hazardous substances, which puts great pressure on production safety and environmental protection. In order to alleviate the above problems, a more effective and green method for synthesizing cordycepin is proposed. Summary of the invention

[0012] In order to overcome the deficiencies of the prior art, the present invention provides a method for preparing cordycepin, which comprises the following steps:

[0013] (1) dissolving compound I, adding an orthoester and an acid catalyst, and reacting to obtain compound II;

[0014] (2) dissolving compound II, adding a hydroxyl protecting agent and a catalyst, and reacting to obtain compound III;

[0015] (3) dissolving compound III, adding an acylating agent dropwise, and reacting to obtain compound IV;

[0016] (4) dissolving compound IV, adding a halide, and reacting to obtain compound V;

[0017] (5) dissolving compound V, adding an alkaline reagent, a reducing agent and an initiator to react to obtain compound VI;

[0018] (6) dissolving compound VI, performing an amination reaction, adding a solvent and an alkaline reagent, performing a hydroxyl deprotection reaction, and obtaining cordycepin;

[0019] The synthetic route of the method is as follows:

[0020]

[0021] in,

[0022] R1 is selected from: substituted or unsubstituted C 1-6 alkyl;

[0023] R2 is selected from: substituted or unsubstituted C 1-6 Alkyl, phenylalkyl;

[0024] R3 is selected from: substituted or unsubstituted C1-6 Alkyl, C 3-6 Cycloalkyl, phenyl, phenylalkyl, -OR6;

[0025] R4 is selected from: substituted or unsubstituted C 1-6 Alkyl, phenylalkyl;

[0026] R5 is halogen (such as F, Br, Cl, I);

[0027] R6 is selected from: C 1-6 Alkyl, phenyl, phenylalkyl.

[0028] Specifically, R1 may be methyl or ethyl, especially methyl.

[0029] Specifically, R2 can be methyl, ethyl, n-propyl, n-butyl or benzyl, especially methyl.

[0030] Specifically, R3 can be selected from: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl, benzyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, tert-butoxy, phenoxy or benzyloxy, especially methyl.

[0031] Specifically, R4 can be methyl, ethyl, n-propyl, n-butyl or benzyl, especially methyl.

[0032] In some embodiments of the present invention, R5 is Br.

[0033] Specifically, Compound I can be a commercially available product.

[0034] Specifically, the acid catalyst in step (1) is at least one of methanesulfonic acid, benzenesulfonic acid, sulfuric acid, trichloroacetic acid, dichloroacetic acid, acetic acid or p-toluenesulfonic acid.

[0035] In some embodiments of the present invention, the acid catalyst is dichloroacetic acid.

[0036] Specifically, the orthoester in step (1) is at least one of trimethyl orthoacetate, triethyl orthoacetate, and trimethyl orthoformate.

[0037] In some embodiments of the present invention, the orthoester is trimethyl orthoacetate.

[0038] Specifically, the molar ratio of the acid catalyst to compound I in step (1) is 0.06:1 to 0.2:1, for example, 0.06:1, 0.08:1, 0.1:1, 0.12:1, 0.12:1, 0.16:1 or 0.2:1, etc.

[0039] Specifically, in step (1), the molar ratio of the orthoester to compound I is 2.0:1 to 3:1, for example, 2.0:1, 2.3:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1 or 3:1.

[0040] Specifically, the reaction temperature in step (1) is 45-65°C, such as 45°C, 50°C, 55°C, 60°C or 65°C.

[0041] In some embodiments of the present invention, the molar ratio of the acid catalyst to compound I is 0.12:1; the molar ratio of the orthoester to compound I is 2.5:1; and the reaction temperature is 55°C.

[0042] Specifically, the step (1) includes post-processing operations, which specifically include: quenching the reaction, concentrating, dissolving, recrystallizing, and drying.

[0043] In some embodiments of the present invention, the method of quenching the reaction in step (1) is to add an alkaline reagent to the reaction.

[0044] Specifically, the alkaline reagent is at least one of triethylamine, butylamine, pentylamine, hexylamine, diethylamine, dibutylamine, dipentylamine, tributylamine, aniline, N-methylaniline, N,N-diisopropylethylamine, imidazole, pyrrole, piperazine, pyrazine, pyridine, sodium methoxide, sodium ethoxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide or barium hydroxide.

[0045] In some embodiments of the present invention, the alkaline agent used to adjust the pH is N,N-diisopropylethylamine.

[0046] Specifically, the solvent used for the dissolution in step (1) is a mixed solvent of methanol and chloroform (solvent I-2), and the volume content of methanol in chloroform is 10% to 50%, for example, 10%, 15%, 20%, 25%, 30%, 45% or 50%, etc.

[0047] Specifically, the recrystallization in step (1) is carried out by dropping the poor solvent I-3 into the solvent I-2 system.

[0048] Specifically, the poor solvent is at least one of petroleum ether, n-heptane, acetone, toluene, ethylbenzene, propylbenzene or water.

[0049] Specifically, the hydroxyl protecting agent described in step (2) is at least one of methyl chloroformate, ethyl chloroformate, propyl chloroformate, isopropyl chloroformate, n-butyl chloroformate, isobutyl chloroformate, tert-butyl chloroformate, phenyl chloroformate, benzyl chloroformate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, diisobutyl carbonate, di-tert-butyl carbonate, diphenyl carbonate, dibenzyl carbonate, acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, n-valeric anhydride, isovaleric anhydride, pivalic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, benzoic anhydride, benzylcarboxylic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride or di-tert-butyl dicarbonate.

[0050] In some embodiments of the present invention, the hydroxyl protecting agent is acetic anhydride.

[0051] Specifically, the catalyst described in step (2) is at least one of 4-dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DDC), N,N'-diisopropylcarbodiimide (DIC), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC), 1,8-diazabicycloundec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), phosphazene-based P2-t-Bu solution (tBu-P2) or trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB).

[0052] In some embodiments of the present invention, the catalyst is 4-dimethylaminopyridine (DMAP).

[0053] Specifically, the solvent used to dissolve the compound II described in step (2) is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran.

[0054] In some embodiments of the present invention, the solvent is dichloromethane.

[0055] Specifically, the molar ratio of the hydroxyl protecting agent to compound II in step (2) is 1.0:1 to 2.0:1, for example, 1.0:1, 1.2:1, 1.4:1, 1.6:1, 1.8:1 or 2.0:1.

[0056] Specifically, the reaction temperature in step (2) is 15-35°C, for example, 15°C, 20°C, 25°C, 30°C or 35°C.

[0057] Specifically, the reaction time in step (2) is 8 to 16 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours or 16 hours.

[0058] In some embodiments of the present invention, the reaction time of step (2) is 12 hours and the reaction temperature is room temperature.

[0059] Specifically, the step (2) includes post-treatment operations, which specifically include: adjusting pH, concentrating, and obtaining compound III.

[0060] Specifically, the reagent used for adjusting the pH in step (2) is at least one of triethylamine, butylamine, pentylamine, hexylamine, diethylamine, dibutylamine, dipentylamine, tributylamine, aniline, N-methylaniline, N,N-diisopropylethylamine, imidazole, pyrrole, piperazine, pyrazine, pyridine, sodium methoxide, sodium ethoxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide or barium hydroxide.

[0061] In some embodiments of the present invention, the reagent used to adjust the pH is sodium carbonate. Specifically, the solvent used to dissolve the compound III in step (3) is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran.

[0062] In some embodiments of the present invention, the solvent is dichloromethane.

[0063] Specifically, the acylating agent structure in step (3) is The acylating agent is at least one of acetyl chloride, acetyl bromide, propionyl chloride, propionyl bromide, butyryl chloride, butyryl bromide, isobutyryl chloride, isobutyryl bromide, isovaleryl chloride, isovaleryl bromide, 2-acetoxyisobutyryl bromide, pivaloyl chloride, pivaloyl bromide, benzoyl chloride or benzoyl bromide.

[0064] Specifically, the molar ratio of the acylating agent to compound II in step (3) is 1.0:1 to 2.0:1, for example, 1.0:1, 1.2:1, 1.3:1, 1.5:1, 1.6:1, 1.8:1 or 2.0:1, etc.

[0065] In some embodiments of the present invention, the molar ratio of the acylating agent to compound II is 1.5:1.

[0066] Specifically, the reaction temperature in step (3) is 0-15°C, such as 0°C, 5°C, 10°C or 15°C.

[0067] Specifically, the reaction time in step (3) is 4 to 15 h, for example, 4 h, 6 h, 9 h, 11 h, 13 h or 15 h.

[0068] Specifically, the step (3) includes post-treatment operations, which specifically include: adding an alkaline reagent to quench the system, adding a benign solvent to extract, drying, and concentrating.

[0069] Specifically, the benign solvent described in step (3) is at least one of dichloromethane, ethyl acetate, tetrahydrofuran or 2-methyltetrahydrofuran.

[0070] Specifically, the alkaline reagent described in step (3) is at least one of triethylamine, butylamine, pentylamine, hexylamine, diethylamine, dibutylamine, dipentylamine, tributylamine, aniline, N-methylaniline, N,N-diisopropylethylamine, imidazole, pyrrole, piperazine, pyrazine, pyridine, sodium methoxide, sodium ethoxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide or barium hydroxide.

[0071] In some embodiments of the present invention, the alkaline agent is sodium carbonate. Specifically, the solvent used to dissolve the compound IV in step (4) is at least one of chloroform, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran.

[0072] In some embodiments of the present invention, the solvent is acetonitrile.

[0073] Specifically, the reaction in step (4) further requires the addition of N,N-dimethylaniline and tetraethylammonium chloride.

[0074] Specifically, in step (4), the molar ratio of compound IV to N,N-dimethylaniline is 1:2 to 1:3, for example, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8 or 1:3.

[0075] Specifically, the molar ratio of compound IV to tetraethylammonium chloride in step (4) is 1:1.2 to 1:2.5, for example, 1:1.2, 1:1.4, 1:1.5, 1:1.7, 1:1.9, 1:2.1, 1:2.3 or 1:2.5, etc. Specifically, the halide in step (4) is at least one of thionyl chloride, phosphorus oxychloride, phosphorus pentachloride or p-toluenesulfonyl chloride (TsCl).

[0076] In some embodiments of the present invention, the halide is phosphorus oxychloride.

[0077] Specifically, the molar ratio of compound IV to the halide in the reaction described in step (4) is 1:1.5 to 1:10.0, for example 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.5, 1:5.0, 1:5.5, 1:6.0, 1:6.5, 1:7.0, 1:8.5, 1:9.0 or 1:10.0, etc.

[0078] In some embodiments of the present invention, the molar ratio of compound IV to halide in the reaction is 1:2.9.

[0079] Specifically, the reaction temperature in step (4) is 40-90°C, for example, 40°C, 45°C, 50°C, 60°C, 65°C, 72°C, 76°C, 78°C, 80°C, 83°C, 85°C, 90°C.

[0080] In some embodiments of the present invention, the reaction temperature is 78°C.

[0081] Specifically, the reaction time in step (4) is 1 to 14 h, for example, 1.5 h, 2.0 h, 4.0 h, 8.0 h, 12.0 h, 14.0 h.

[0082] Specifically, the reaction in step (4) needs to be carried out under the protection of an inert gas.

[0083] Preferably, the inert gas is selected from nitrogen or argon.

[0084] Specifically, the step (4) includes post-treatment operations, which specifically include: quenching the reaction system, extracting with a benign solvent, washing, and concentrating.

[0085] Specifically, the reaction system quenching method in step (4) is: the system is slowly added dropwise into ice water, and the dropping speed must be controlled and not too fast.

[0086] Specifically, the benign solvent in step (4) is at least one of dichloromethane, ethyl acetate, tetrahydrofuran or 2-methyltetrahydrofuran.

[0087] In some embodiments of the present invention, the benign solvent is dichloromethane.

[0088] Specifically, the solvent used to dissolve the compound V described in step (5) is at least one of benzene, toluene, ethylbenzene, propylbenzene, tert-butylbenzene, xylene, chlorobenzene, dichlorobenzene, tetrahydrofuran, 1,4-dioxane, acetonitrile, nitrobenzene, anisole, water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol.

[0089] In some embodiments of the present invention, the solvent used to dissolve the compound V is acetonitrile.

[0090] Specifically, the alkaline reagent described in step (5) is at least one of triethylamine, butylamine, pentylamine, hexylamine, diethylamine, dibutylamine, dipentylamine, tributylamine, aniline, N-methylaniline, imidazole, pyrrole, piperazine, pyrazine, pyridine, sodium methoxide, sodium ethoxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, ammonia water or ammonia methanol solution.

[0091] Specifically, the reducing agent in step (5) is hypophosphorous acid.

[0092] Specifically, the initiator described in step (5) is at least one of azobiscyclohexylcarbonitrile (VA-044), dimethyl azobisisobutyrate (AIBME), azobisisobutyramidine hydrochloride (V-50), azobisisobutyronitrile (AIBN), lauroyl peroxide (LPO), isopropylbenzene hydroperoxide (CHP), tert-butyl hydroperoxide (TBHP), methyl ethyl ketone peroxide (MEKP), dicyclohexyl peroxydicarbonate (DCPD), diisopropyl peroxydicarbonate (IPP), benzoyl peroxide (BPO), cyclohexanone peroxide (CADOX HDP), di-tert-butyl peroxide (DTBP), tert-butyl peroxytivalate (BPP), tert-butyl perbenzoate (DBPB) or diisopropyl peroxide (DCP).

[0093] In some embodiments of the present invention, the initiator is azobiscyclohexylcarbonitrile (VA-044).

[0094] In some embodiments of the present invention, the reducing agent described in step (5) is first dissolved in water and then prepared with an alkaline reagent to form a mixed solution, wherein the solvent of the mixed solution is water.

[0095] Specifically, the molar ratio of compound V to the reducing agent in step (5) is 1:2 to 1:8, for example, 1:2.0, 1:2.5, 1:2.8, 1:3.0, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4.0, 1:6.0, 1:7.4 or 1:8.0, etc.

[0096] In some embodiments of the present invention, the molar ratio of compound V to the reducing agent is 1:3.2.

[0097] Specifically, the molar ratio of compound V to the initiator in step (5) is 1:0.05 to 1:0.5, for example, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4 or 1:0.5, etc.

[0098] In some embodiments of the present invention, the molar ratio of compound V to initiator is 1:0.15.

[0099] Specifically, the reaction temperature in step (5) is 40°C to 60°C, such as 40°C, 45°C, 50°C, 55°C or 60°C.

[0100] Specifically, the reaction time in step (5) is 4 to 10 h, for example, 4 h, 6 h, 7 h, 8 h, 9 h or 10 h.

[0101] In some embodiments of the present invention, the reaction temperature is 50° C. and the reaction time is 6 hours.

[0102] Specifically, the step (5) includes post-processing operations, and the specific operations include: benign solvent extraction, drying, and concentration.

[0103] Specifically, the benign solvent in step (5) is at least one of dichloromethane, ethyl acetate, tetrahydrofuran or 2-methyltetrahydrofuran.

[0104] In some embodiments of the present invention, the benign solvent is dichloromethane. Specifically, in the amination reaction described in step (6), the solvent (VI-1) used to dissolve compound VI is at least one of tetrahydrofuran, ethylene glycol dimethyl ether, dimethylacetamide, N-methylpyrrolidone, acetone, acetonitrile, 1,4-dioxane, dimethyl sulfoxide or N,N-dimethylformamide.

[0105] In some embodiments of the present invention, the solvent for dissolving compound VI is tetrahydrofuran.

[0106] Specifically, the amination reaction in step (6) needs to be carried out under a nitrogen atmosphere.

[0107] Specifically, in the dehydroxylation protection reaction described in step (6), the solvent (VI-2) is at least one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol.

[0108] Specifically, the alkaline reagent described in step (6) is at least one of sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, ammonia water, sodium methoxide, sodium ethoxide or ammonia methanol solution.

[0109] In some embodiments of the present invention, the alkaline agent is sodium methoxide.

[0110] Specifically, the amination reaction time in step (6) is 24 to 96 h, for example, 24 h, 36 h, 48 h, 60 h, 72 h, 84 h or 96 h.

[0111] In some embodiments of the present invention, the amination reaction time is 72 hours.

[0112] Specifically, the hydroxyl deprotection reaction time in step (6) is 3 to 12 h, such as 3 h, 4 h, 6 h, 8 h, 10 h or 12 h.

[0113] In some embodiments of the present invention, the hydroxyl deprotection reaction time is 6 hours.

[0114] Specifically, the dehydroxylation protection reaction in step (6) includes post-treatment operations, and the specific operations include: concentration, recrystallization, and drying.

[0115] Specifically, the recrystallization method described in step (6) is: adding ethanol / ethyl acetate solutions in different proportions and cooling to crystallize.

[0116] Specifically, the ratio of ethanol / ethyl acetate solution is 1:2 to 1:30, for example, 1:2, 1:5, 1:8, 1:12, 1:15, 1:20, 1:24, 1:27 or 1:30, etc.

[0117] In one embodiment of the present invention, step (1) comprises: dissolving compound I in solvent I-1, adding orthoester, dropping acid catalyst, and after the dropping is complete, heating to 50-60°C for reaction; cooling after the reaction is complete, quenching the reaction, concentrating, adding solvent I-2 to dissolve and dilute, dropping solvent I-3, separating the precipitate, drying, and obtaining compound II.

[0118] In one embodiment of the present invention, step (2) comprises: dissolving compound II in a solvent, adding a hydroxyl protecting agent and a catalyst, and reacting at room temperature; after the reaction is completed, adjusting the pH and concentrating to obtain compound III.

[0119] In one embodiment of the present invention, step (3) comprises: dissolving compound III in a solvent, adding an acylating agent dropwise, and reacting at 0 to 15°C; after the reaction is completed, adding an alkaline agent at low temperature to quench the system, extracting, drying, and concentrating to obtain compound IV.

[0120] In one embodiment of the present invention, step (4) comprises: dissolving compound IV in a solvent, adding N,N-dimethylaniline and tetraethylammonium chloride, adding a halogenated compound dropwise at room temperature under the protection of an inert gas, raising the temperature to 40 to 90° C., and reacting; after the reaction is completed, cooling, dropping the reaction system into ice water to quench, extracting, washing, and concentrating to obtain compound V.

[0121] In one embodiment of the present invention, step (5) comprises: dissolving compound V in a solvent, heating to 40°C to 60°C, adding a mixed solution, and then adding an alkaline reagent and an initiator to react; after the reaction is completed, cooling, extracting, drying, and concentrating to obtain compound VI.

[0122] In one embodiment of the present invention, step (6) comprises: dissolving compound VI in solvent VI-1 and reacting under a nitrogen atmosphere; after the reaction is completed, concentrating, and then adding solvent VI-2 and an alkaline reagent to react; after the reaction is completed, concentrating, recrystallizing by adjusting the ratio of ethanol / ethyl acetate solution, and drying to obtain cordycepin.

[0123] In another aspect of the present invention, there is provided the use of the cordycepin method of the present invention in the preparation of anti-tumor, anti-viral and immunomodulatory drugs.

[0124] Specifically, anti-tumor diseases include, but are not limited to: oral cancer, lung cancer, liver cancer, breast cancer, cervical cancer, colon cancer, bladder cancer, thyroid cancer, lymphoma, melanoma, brain tumor, Ehrlich ascites tumor, multiple myeloma, etc.

[0125] Specifically, cordycepin has multiple regulatory effects on pathogenic microorganisms such as bacteria, fungi, and viruses.

[0126] Specifically, the fungi include but are not limited to: Bacillus subtilis, Clostridium, Bacillus anthracis, Microsporum tinea, Microsporum woolly, Trichophyton mentagrophytes, etc.

[0127] Specifically, the bacteria include but are not limited to: Staphylococcus aureus, Candida, Streptococcus, Escherichia coli, etc.

[0128] Viruses include but are not limited to: leukemia virus, human herpes virus, influenza virus type 4, Western equine encephalitis virus, Newcastle disease virus, Western equine encephalitis virus, SemLiki Forest virus, Hantan virus, human immunodeficiency virus, etc.

[0129] Specifically, immune-regulated diseases include, but are not limited to, rheumatoid arthritis, contact dermatitis caused by hypersensitivity reactions, Alzheimer's disease, Parkinson's disease, multiple sclerosis, trauma and cerebral ischemia, chronic asthma, and the like.

[0130] The synthetic route of the present invention has advantages. Firstly, the raw material inosine used is cheap and easily available, which can save the raw material cost and is conducive to industrial scale-up. Secondly, no metal catalyst is required in the synthetic step, which reduces the cost and is more environmentally friendly. In addition, the overall synthetic process is simple, which is convenient for scale-up operation, the post-processing operation is simple, the yield is high, and it is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0131] Figure 1 Shown is the H NMR spectrum of compound V'.

[0132] Figure 2 Shown is the H NMR spectrum of the product. DETAILED DESCRIPTION

[0133] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0134] Unless otherwise defined, all scientific and technical terms used in the present invention have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention relates.

[0135]

[00136] Various publications, patents, and published patent specifications are cited herein, the disclosures of which are incorporated by reference in their entireties.

[0136] The method for synthesizing cordycepin of the present invention comprises the following steps:

[0137] Overall reaction formula:

[0138]

[0139] Example 1: Synthesis of Compound II':

[0140]

[0141] In a dry round-bottom flask, 50g of inosine (compound I, 1eq) and 250mL of DMF were mixed evenly, 60mL (2.5eq) of trimethyl orthoacetate was added to the above suspension, and then 2mL (0.12eq) of dichloroacetic acid was added dropwise. After the addition was complete, the temperature was raised to 55°C and the reaction was allowed to proceed for 5h. After the reaction was completed, the temperature was lowered to room temperature, 10mL of DIPEA was added, and the mixture was stirred for 10min. Most of the DMF in the reaction solution was then removed by rotation, and the mixture was dissolved and diluted with 300mL of 20% methanol / chloroform. After stirring evenly, petroleum ether was added dropwise until the product was completely precipitated. The solvent was removed by suction filtration, and the white solid product (compound II') was obtained after drying in a vacuum drying oven. The weight was 56.5g, and the yield was 94.2%.

[0142] Example 2: Synthesis of Compound IV':

[0143]

[0144] In a dry round-bottom flask, 20g of compound II' was dissolved in 150mL of dichloromethane, 7.6mL (1.42eq) of acetic anhydride and 100mg of DMAP were added, and the mixture was stirred at room temperature for 12h to generate compound III. 10% Na2CO3 was added dropwise to adjust the pH to 9, and the mixture was extracted and dried to obtain a white powder (compound III'). The mixture was dissolved in 150mL of dichloromethane, cooled to 5°C, and 8mL (1.49eq) of acetyl bromide was added dropwise. After the addition was completed, the mixture was heated to 10°C and the reaction was continued for 9h. After the reaction was completed, 10% Na2CO3 was added dropwise under an ice bath to adjust the pH to 7, and then the mixture was extracted with 50mL x 5 dichloromethane. The organic phase obtained by the extraction was dried and concentrated to obtain 24.3g of a yellow hard foam product (compound IV') with a yield of 94%.

[0145] Example 3: Synthesis of Compound V':

[0146]

[0147] In a dry three-necked flask, 10 g of compound IV', 45 mL of anhydrous acetonitrile, 8 mL (2.6 eq) of N,N-dimethylaniline, and 7.5 g (1.9 eq) of tetraethylammonium chloride were added. The gas in the container was replaced with nitrogen after the container was sealed. Then 6.5 mL (2.9 eq) of phosphorus oxychloride was added dropwise at room temperature. After the addition was completed, the temperature was raised to 78 ° C and refluxed for 1.5 h. After the reaction was completed, the temperature was lowered. Then the reaction solution was added dropwise to 100 mL of ice water, extracted with 20 mL × 5 of dichloromethane, and then the organic phase was washed with 12% dilute hydrochloric acid. After being spin-dried, 11.6 g of light brown ointment (compound V', whose NMR spectrum is shown in Figure 1 The yield was 93%.

[0148] Example 4: Synthesis of Compound VI':

[0149]

[0150] In a dry three-necked round-bottom flask, dissolve 2.75g of compound V' (1eq) in 4mL of acetonitrile and heat to 50°C. Prepare a mixed solution: dissolve 2.1mL (3.15eq) of 50% hypophosphorous acid aqueous solution in 10mL of water, then add 2.8mL (3.15eq) of triethylamine. Add the mixed solution to the system, mix well, adjust the pH to 8 with triethylamine, then add 0.3g of VA-044 (0.15eq) and react for 6h. After the reaction is completed, cool the reaction, extract with 10mL×3 of dichloromethane, dry, and rotary evaporate to obtain 2.2g of yellow viscous oil paste product (compound VI'), with a yield of 98%.

[0151] Example 5: Synthesis of Cordycepin:

[0152]

[0153] 8.21 g of compound VI' and 50 mL of dry tetrahydrofuran were placed in a dry reactor and reacted at 70°C for three days under a 6 bar ammonia atmosphere. After the reaction, THF in the reaction solution was removed, 50 mL of methanol and 2.63 g (2.1 eq) of sodium methoxide were added, and the reaction was concentrated under reduced pressure for 6 h. The target product was then recrystallized from ethanol / ethyl acetate to obtain 5.2 g of the target product with a yield of 86.5%. The product was confirmed by H-NMR, and the structural identification results are as follows Figure 2 shown.

[0154] Comparative Example

[0155] Compared with the present invention, the reaction order of the third step and the fourth step is adjusted. The overall synthesis reaction route is as follows:

[0156]

[0157] Comparative Example 1: Synthesis of Compound V':

[0158]

[0159] In a dry three-necked round-bottom flask, 5g of compound IV' (1eq, prepared in Example 2) was dissolved in 25mL of acetonitrile, heated to 50°C, and a mixed solution was prepared: 8mL (3.15eq) of 50% hypophosphorous acid aqueous solution was dissolved in 10mL of water, followed by the addition of 11mL (3.15eq) of triethylamine. The mixed solution was added to the system, mixed evenly, and the pH was adjusted to 8 with triethylamine, followed by the addition of 1g of VA-044 (0.15eq), and the reaction was continued for 6h. After the reaction was completed, the reaction was cooled, dried with 10mL of dichloromethane × 3, and 3.15g of white powder (compound V') was obtained after rotary evaporation, with a yield of 82%.

[0160] Comparative Example 2: Synthesis of Compound VI':

[0161]

[0162] In a dry three-necked flask, 7.15 g of compound ⅴ', 40 mL of anhydrous acetonitrile, 7.2 mL (2.7 eq) of N,N-dimethylaniline, and 6.75 g (1.9 eq) of tetraethylammonium chloride were added. The gas in the container was replaced with nitrogen after the container was sealed. Then 5.9 mL (3 eq) of phosphorus oxychloride was added dropwise at room temperature. After the addition was completed, the temperature was raised to 78°C and refluxed for 1.5 h. After the reaction was completed, the temperature was lowered. The reaction solution was then added dropwise to 100 mL of ice water, extracted with 20 mL × 5 of dichloromethane, and then the organic phase was washed with 12% dilute hydrochloric acid. After being spin-dried, 7.04 g of light brown ointment (compound VI') was obtained with a yield of 86%.

[0163] The third and fourth steps of the method of the present invention are in the order of first performing a substitution reaction at C-6 of the purine ring and then performing a dehalogenation reaction at C-3' of the furan ring. As can be seen from the above-mentioned Examples 3 and 4, the yield of the two-step reaction addition is 91.14%; while the reaction order in the comparative example is first performing a dehalogenation reaction and then performing a substitution reaction, which is opposite to the reaction order of the present invention, and the yield of the two-step reaction addition is only 70.5%. It can be seen that the method of the present invention can greatly improve the yield, which is conducive to improving the utilization rate of the raw material inosine and reducing the cost.

[0164] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0165] The aforementioned embodiments and methods described in the present invention may be varied based on the ability, experience and preference of those skilled in the art.

[0166] In the present invention, merely listing the steps of the method in a certain order does not constitute any limitation on the order of the method steps.

Claims

1. A method for preparing cordycepin, comprising the following steps: (1) dissolving compound I, adding an orthoester and an acid catalyst, and reacting to obtain compound II; (2) dissolving compound II, adding a hydroxyl protecting agent and a catalyst, and reacting to obtain compound III; (3) dissolving compound III, adding an acylating agent dropwise, and reacting to obtain compound IV; (4) dissolving compound IV, adding a halide, and reacting to obtain compound V; (5) dissolving compound V, adding an alkaline reagent, a reducing agent and an initiator to react to obtain compound VI; (6) dissolving compound VI, performing an amination reaction, adding a solvent and an alkaline reagent, performing a hydroxyl deprotection reaction, and obtaining cordycepin; The synthetic route of the method is as follows: in, R1 is selected from: substituted or unsubstituted C 1-6 alkyl; R2 is selected from: substituted or unsubstituted C 1-6 Alkyl, phenylalkyl; R3 is selected from: substituted or unsubstituted C 1-6 Alkyl, C 3-6 Cycloalkyl, phenyl, phenylalkyl, -OR6; R4 is selected from: substituted or unsubstituted C 1-6 Alkyl, phenylalkyl; R5 is halogen, including F, Br, Cl, I; R6 is selected from: C 1-6 Alkyl, phenyl, phenylalkyl.

2. The method according to claim 1, characterized in that The acid catalyst in step (1) is at least one of methanesulfonic acid, benzenesulfonic acid, sulfuric acid, trichloroacetic acid, dichloroacetic acid, acetic acid or p-toluenesulfonic acid; Preferably, the orthoester in step (1) is at least one of trimethyl orthoacetate, triethyl orthoacetate, and trimethyl orthoformate; Preferably, the molar ratio of the orthoester to compound I in step (1) is 2.0:1 to 3:1; Preferably, the molar ratio of the acid catalyst to compound I in step (1) is 0.06:1 to 0.2:1; Preferably, the reaction temperature in step (1) is 45-65°C.

3. The method according to claim 1, characterized in that The hydroxyl protecting agent described in step (2) is at least one of methyl chloroformate, ethyl chloroformate, propyl chloroformate, isopropyl chloroformate, n-butyl chloroformate, isobutyl chloroformate, tert-butyl chloroformate, phenyl chloroformate, benzyl chloroformate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, diisopropyl carbonate, dibutyl carbonate, diisobutyl carbonate, di-tert-butyl carbonate, diphenyl carbonate, dibenzyl carbonate, acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, n-valeric anhydride, isovaleric anhydride, pivalic anhydride, cyclopentanecarboxylic anhydride, cyclohexanecarboxylic anhydride, benzoic anhydride, benzylcarboxylic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride or di-tert-butyl dicarbonate; Preferably, the catalyst described in step (2) is at least one of 4-dimethylaminopyridine (DMAP), dicyclohexylcarbodiimide (DDC), N,N'-diisopropylcarbodiimide (DIC), 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC), 1,8-diazabicycloundec-7-ene (DBU), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), phosphazene-based P2-t-Bu solution (tBu-P2) or trans-2-[3-(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB); Preferably, the solvent used to dissolve the compound II in step (2) is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran; Preferably, the reaction temperature in step (2) is 15-35°C.

4. The method according to claim 3, characterized in that The solvent used to dissolve the compound III in step (3) is at least one of dimethyl sulfoxide, N,N-dimethylformamide, dimethylacetamide, N-methylpyrrolidone, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran; Preferably, the acylating agent structure in step (3) is The acylating agent is at least one of acetyl chloride, acetyl bromide, propionyl chloride, propionyl bromide, butyryl chloride, butyryl bromide, isobutyryl chloride, isobutyryl bromide, isovaleryl chloride, isovaleryl bromide, 2-acetoxyisobutyryl bromide, pivaloyl chloride, pivaloyl bromide, benzoyl chloride or benzoyl bromide; Preferably, the molar ratio of the acylating agent to compound II in step (3) is 1.0:1 to 2.0:1; Preferably, the reaction temperature in step (3) is 0 to 15°C; Preferably, the reaction time in step (3) is 4 to 15 hours.

5. The method according to claim 1, 3 or 4, characterized in that: The step (1) includes post-processing operations, which specifically include: quenching the reaction, concentrating, dissolving, recrystallizing, and drying; Preferably, the step (2) includes post-treatment operations, and the specific operations include: adjusting pH and concentrating to obtain compound III; Preferably, the step (3) includes post-treatment operations, and the specific operations include: adding an alkaline reagent to quench the system, adding a benign solvent for extraction, drying, and concentrating.

6. The method according to claim 1, characterized in that The solvent used to dissolve the compound IV in step (4) is at least one of chloroform, dichloromethane, dichloroethane, acetonitrile, acetone or tetrahydrofuran; Preferably, the reaction in step (4) further requires the addition of N,N-dimethylaniline and tetraethylammonium chloride; Preferably, the halogenated compound in step (4) is at least one of thionyl chloride, phosphorus oxychloride, phosphorus pentachloride or p-toluenesulfonyl chloride (TsCl); Preferably, the molar ratio of compound IV to the halide is 1:1.5 to 1:10.0; Preferably, the reaction time in step (4) is 1 to 14 hours.

7. The method according to claim 1, characterized in that The solvent used to dissolve the compound V in step (5) is at least one of benzene, toluene, ethylbenzene, propylbenzene, tert-butylbenzene, xylene, chlorobenzene, dichlorobenzene, tetrahydrofuran, 1,4-dioxane, acetonitrile, nitrobenzene, anisole, water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol; Preferably, the alkaline reagent described in step (5) is at least one of triethylamine, butylamine, pentylamine, hexylamine, diethylamine, dibutylamine, dipentylamine, tributylamine, aniline, N-methylaniline, imidazole, pyrrole, piperazine, pyrazine, pyridine, sodium methoxide, sodium ethoxide, sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, ammonia water or ammonia methanol solution; Preferably, the reducing agent in step (5) is hypophosphorous acid; Preferably, the initiator described in step (5) is at least one of azobiscyclohexylcarbonitrile (VA-044), dimethyl azobisisobutyrate (AIBME), azobisisobutyramidine hydrochloride (V-50), azobisisobutyronitrile (AIBN), lauroyl peroxide (LPO), cumene hydroperoxide (CHP), tert-butyl hydroperoxide (TBHP), methyl ethyl ketone peroxide (MEKP), dicyclohexyl peroxydicarbonate (DCPD), diisopropyl peroxydicarbonate (IPP), benzoyl peroxide (BPO), cyclohexanone peroxide (CADOX HDP), di-tert-butyl peroxide (DTBP), tert-butyl peroxytivalate (BPP), tert-butyl perbenzoate (DBPB) or diisopropyl peroxide (DCP); Preferably, the molar ratio of compound V to the reducing agent in step (5) is 1:2 to 1:8.0, and the molar ratio of compound V to the initiator is 1:0.05 to 1:0.5; Preferably, the reaction temperature in step (5) is 40°C to 60°C; Preferably, the reaction time in step (5) is 4 to 10 hours.

8. The method according to claim 1, characterized in that In the amination reaction in step (6), the solvent used to dissolve compound VI is at least one of tetrahydrofuran, ethylene glycol dimethyl ether, dimethylacetamide, N-methylpyrrolidone, acetone, acetonitrile, 1,4-dioxane, dimethyl sulfoxide or N,N-dimethylformamide; Preferably, in the dehydroxylation protection reaction described in step (6), the solvent is at least one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol or tert-butanol; Preferably, the alkaline reagent described in step (6) is at least one of sodium bicarbonate, potassium bicarbonate, ammonium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, cesium carbonate, ammonium carbonate, sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide, barium hydroxide, ammonia water or ammonia methanol solution; Preferably, the amination reaction time in step (6) is 24 to 96 hours; Preferably, the hydroxyl deprotection reaction time in step (6) is 3 to 12 hours.

9. The method according to claim 1, 6, 7 or 8, characterized in that The step (4) includes post-treatment operations, which specifically include: quenching the reaction system, extracting with a benign solvent, washing, and concentrating; Preferably, the step (5) includes post-processing operations, and the specific operations include: benign solvent extraction, drying, and concentration; Preferably, the dehydroxylation protection reaction in step (6) includes post-treatment operations, and the specific operations include: concentration, recrystallization, and drying.

10. Use of the method according to any one of claims 1 to 9 in the preparation of anti-tumor, anti-viral and immunomodulatory drugs.

Images