A p-benzoquinone derivative and a method for synthesizing the same

Abstract

This invention provides a rapid synthesis method for p-benzoquinone derivatives, comprising: using a phenol derivative as a raw material as shown in formula (2) as a raw material, and oxidizing it with a high-valent iodine reagent to obtain the p-benzoquinone derivative shown in formula (1) in one step. The conditions for the one-step synthesis include: a reaction temperature equal to or below 10°C. This invention also provides a p-benzoquinone derivative synthesized by the above method. Compared with the prior art, this invention uses simple phenolic compounds as substrates and trivalent iodine as an oxidant, and can rapidly and efficiently obtain quinone compounds in one step, which shortens the reaction steps and avoids the use of dangerous reagents tert-butyl peroxide and titanium tetrachloride.

Description

Technical Field

[0001] This invention relates to the field of synthesis of p-benzoquinone derivatives, and more particularly to a method for synthesizing p-benzoquinone derivatives and the p-benzoquinone derivatives synthesized by the method. Background Technology

[0002] p-Benzoquinone derivatives are important synthons in organic synthesis, serving as diephiles in Diels-Alder reactions, acceptors in Michael addition reactions, and substrates in reduction reactions. Furthermore, the structure of p-benzoquinone is also found in some biologically active natural products, such as Cordiachrome C, Mitomycin C, and Avarone, as shown below:

[0003]

[0004] The synthesis of p-benzoquinone derivatives containing fused rings (such as the benzoquinone derivatives shown in formula (1)) by existing technologies usually requires multiple steps of reaction.

[0005] Taking the synthesis of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6) as an example (J.Org.Chem.2007,72,4981-4984), its synthesis uses 5,6,7,8-tetrahydro-2-naphthol (3) as a raw material. It first reacts with tert-butyl peroxide to generate peroxide compound (4). Compound (4) is treated with TiCl4 to obtain diphenol (5). Finally, under the oxidation of cerium ammonium nitrate, the product naphthoquinone (6) is obtained. The reaction process is shown below.

[0006]

[0007] The above reaction route requires three steps and uses overly dangerous reagents, such as tert-butyl peroxide and titanium metal reagents.

[0008] Patent CN113773221A discloses a one-step method for synthesizing p-benzoquinone compounds by oxidizing methyl acetanilide or p-ethyl acetanilide. This method requires N,N-dimethylformamide (DMF) as a solvent, and the reaction time is usually 12-16 hours. The drawbacks of this method include: (1) due to the high boiling point of N,N-dimethylformamide, it is miscible with water and most organic solvents, making it difficult to remove completely; (2) the reaction time is relatively long. Summary of the Invention

[0009] Based on the above, one of the objectives of this invention is to provide a method for synthesizing benzoquinone derivatives. This method uses phenolic ring-shaped compounds as substrates and can achieve one-step synthesis of benzoquinone derivatives, which is simple and efficient.

[0010] The second objective of this invention is to provide a p-benzoquinone derivative synthesized by the above-described method for synthesizing p-benzoquinone derivatives.

[0011] Therefore, in a first aspect, the present invention provides a method for synthesizing a p-benzoquinone derivative, comprising: using a phenol derivative of formula (2) as a raw material and oxidizing it with a high-valent iodine reagent to obtain a p-benzoquinone derivative of formula (1), wherein the oxidation conditions include: the reaction temperature being equal to or lower than 10°C;

[0012]

[0013] Where n is an integer selected from 1 to 4.

[0014] As a specific embodiment of the present invention, the oxidation conditions include: the raw material is dissolved in an organic solvent and the oxidation is carried out under an inert gas atmosphere.

[0015] In a specific embodiment of the present invention, the organic solvent includes at least one of methanol and ethanol. The organic solvent selected in this invention is an alcohol compound, which can be removed by rotary evaporation, significantly reducing the reaction time and making it simple and efficient.

[0016] As a specific embodiment of the present invention, the inert gas is selected from at least one of nitrogen, helium and argon.

[0017] In a specific embodiment of the present invention, the organic solvent is methanol. The use of methanol as the organic solvent in this invention can further improve the yield of the method for synthesizing p-benzoquinone derivatives.

[0018] As a specific embodiment of the present invention, the oxidation conditions include a reaction temperature of -15°C to 10°C. The method of the present invention is carried out at this temperature, which can further improve the yield of the synthesis of p-benzoquinone derivatives.

[0019] As a specific embodiment of the present invention, the oxidation conditions include a reaction temperature of -10°C to 5°C. The method of the present invention is carried out at this temperature, which can further improve the yield of the synthesis of p-benzoquinone derivatives.

[0020] As a specific embodiment of the present invention, the oxidation conditions include a reaction temperature of -5°C to 0°C. The method of the present invention is carried out at this temperature, which can further improve the yield of the synthesis of p-benzoquinone derivatives.

[0021] In a specific embodiment of the present invention, the oxidation conditions include a reaction time of 2 to 8 hours, preferably 3 to 6 hours. The method of the present invention can rapidly and efficiently obtain quinone compounds, and the reaction time is significantly shorter than that of existing technologies.

[0022] In a specific embodiment of the present invention, the high-valent iodine reagent is a trivalent iodine reagent.

[0023] As a specific embodiment of the present invention, the trivalent iodine reagent is selected from at least one of dichloroiodobenzene and iodophenyl diacetic acid, preferably iodophenyl diacetic acid (or diiodobenzene acetate).

[0024] As a specific embodiment of the present invention, the molar ratio of the phenol derivative shown in formula (2) to the high-valent iodine reagent is 1:1 to 3.

[0025] In a specific embodiment of the present invention, the oxidation is carried out under stirring conditions.

[0026] As a specific embodiment of the present invention, the stirring speed is 500-1000 rpm, preferably 600-1000 rpm.

[0027] As a specific embodiment of the present invention, the synthesis method further includes adding a quenching agent after oxidation to obtain the reaction product.

[0028] In a specific embodiment of the present invention, the quenching agent comprises an ammonium chloride solution with a concentration of 3 mol / L to 7 mol / L. In some embodiments, the quenching agent is a saturated ammonium chloride solution with a concentration of 3 mol / L. In some embodiments, the quenching agent is a saturated ammonium chloride solution.

[0029] As a specific embodiment of the present invention, the synthesis method further includes: adding an extraction solvent to the reaction product for extraction and separation to obtain an organic phase and an aqueous phase; drying the organic phase to obtain a crude product; and separating the residues in the crude product to obtain the final product.

[0030] As a specific embodiment of the present invention, the extraction solvent includes at least one of ethyl acetate, dichloromethane, and tetrahydrofuran.

[0031] In a specific embodiment of the present invention, the extraction and separation are performed 1 to 5 times.

[0032] In a specific embodiment of the present invention, the organic phase is dried by adding a desiccant.

[0033] As a specific embodiment of the present invention, the desiccant includes at least one of anhydrous sodium sulfate and anhydrous magnesium chloride.

[0034] As a specific embodiment of the present invention, the residues in the crude product are separated by column chromatography.

[0035] As a specific embodiment of the present invention, the column chromatography packing material is silica gel, and the eluent is a petroleum ether solution of 2wt% to 5wt% ethyl acetate.

[0036] As a specific embodiment of the present invention, the method for preparing p-benzoquinone derivatives provided by the present invention specifically includes the following steps:

[0037] a) Dissolve the phenol derivative shown in formula (2) in an organic solvent and purge it with nitrogen gas for protection;

[0038] b) Cool the reaction system obtained in step a) to -10℃ to 0℃;

[0039] c) Add high-valent iodine reagent under a nitrogen atmosphere and stir continuously for 2 to 8 hours while maintaining the temperature at -10℃ to 0℃;

[0040] d) After the reaction is complete, a quenching agent is added to quench the reaction. Extraction solvent is added and the mixture is extracted and separated several times to obtain an organic phase and an aqueous phase. The organic phases are combined and dried to obtain a crude product. The residue in the crude product is separated to obtain the target product.

[0041] Therefore, in a second aspect, the present invention provides a p-benzoquinone derivative obtained by the above-mentioned method for synthesizing p-benzoquinone derivatives.

[0042] The beneficial effects of this invention are as follows:

[0043] Compared with existing technologies, this invention uses simple phenolic compounds as substrates and trivalent iodine as an oxidant to rapidly and efficiently obtain quinone compounds in one step, which shortens the reaction steps and avoids the use of dangerous reagents such as tert-butyl peroxide and titanium tetrachloride.

[0044] Compared with existing technologies, this invention uses alcohols as solvents, which simplifies post-reaction processing. The alcohols can be removed by rotary evaporation, and the reaction time is significantly shortened. This invention is simple, efficient, and yields a high rate of change. Detailed Implementation

[0045] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0046] The following examples will provide a detailed description:

[0047] Example 1

[0048] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0049] The specific operating steps are as follows: Take a dried 25 mL three-necked flask, add 74 mg of 5,6,7,8-tetrahydronaphthol and 10 mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to 0 °C, add 387 mg of iodophenyldiacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the starting material reacted completely. Then, add 5 mL of ammonium chloride solution (25 °C, 6.95 mol / L) to the reaction system to quench the reaction. Add 5 mL of ethyl acetate and 5 mL of ammonium chloride solution to the obtained reaction product to extract the first aqueous phase and the first organic phase. Add 5 mL of ethyl acetate to the first aqueous phase to extract the second aqueous phase and the second organic phase. Add 5 mL of ethyl acetate to the second aqueous phase to extract the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 69.7 mg of a pale yellow oily liquid product, characterized by NMR 1H NMR spectroscopy. 1 1H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0050] The structural formula of 5,6,7,8-tetrahydronaphthol is shown in formula (7).

[0051]

[0052] Example 2

[0053] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0054] The specific operating steps are as follows: Take a dried 25mL three-necked flask, add 72mg of 5,6,7,8-tetrahydronaphthol and 10mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to 0℃, add 330mg of dichloroiodobenzene under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the reactants reacted completely. Then, add 5mL of ammonium chloride solution (25℃, 6.95mol / L) to the reaction system to quench the reaction. Add 5mL of ethyl acetate and 5mL of ammonium chloride solution to the obtained reaction product for extraction to obtain the first aqueous phase and the first organic phase. Add 5mL of ethyl acetate to the first aqueous phase for extraction to obtain the second aqueous phase and the second organic phase. Add 5mL of ethyl acetate to the second aqueous phase for extraction to obtain the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 43.5 mg of a pale yellow oily liquid product, characterized by NMR ¹H₂O. 1 1H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0055] Example 3

[0056] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0057] The specific operating steps are as follows: Take a dried 25mL three-necked flask, add 75mg of 5,6,7,8-tetrahydronaphthol and 10mL of anhydrous ethanol, and purge with nitrogen three times. Cool the reaction system to 0℃, add 388mg of iodophenyldiacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the starting material reacted completely. Then, add 5mL of ammonium chloride solution (25℃, 6.95mol / L) to the reaction system to quench the reaction. Add 5mL of ethyl acetate and 5mL of ammonium chloride solution to the obtained reaction product for extraction to obtain the first aqueous phase and the first organic phase. Add 5mL of ethyl acetate to the first aqueous phase for extraction to obtain the second aqueous phase and the second organic phase. Add 5mL of ethyl acetate to the second aqueous phase for extraction to obtain the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 12.7 mg of a pale yellow oily liquid product, characterized by NMR ¹H₂O. 11H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0058] Example 4

[0059] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0060] The specific operating steps are as follows: Take a dried 25 mL three-necked flask, add 74 mg of 5,6,7,8-tetrahydronaphthol and 10 mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to -10 °C, add 387 mg of iodophenyldiacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the reactants were almost completely reacted. Then, add 5 mL of ammonium chloride solution (25 °C, 6.95 mol / L) to the reaction system to quench the reaction. Extract the obtained reaction product with 5 mL of ethyl acetate and 5 mL of ammonium chloride solution to obtain the first aqueous phase and the first organic phase. Extract the first aqueous phase with 5 mL of ethyl acetate to obtain the second aqueous phase and the second organic phase. Extract the second aqueous phase with 5 mL of ethyl acetate to obtain the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 42.4 mg of a pale yellow oily liquid product, characterized by NMR ¹H NMR. 1 1H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0061] Example 5

[0062] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0063] The specific operating steps are as follows: Take a dried 25 mL three-necked flask, add 74 mg of 5,6,7,8-tetrahydronaphthol and 10 mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to 10 °C, add 387 mg of iodophenyldiacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the reaction proceeds were complete. Then, add 5 mL of ammonium chloride solution (25 °C, 6.95 mol / L) to the reaction system to quench the reaction. Extract the obtained reaction product with 5 mL of ethyl acetate and 5 mL of ammonium chloride solution to obtain the first aqueous phase and the first organic phase. Extract the first aqueous phase with 5 mL of ethyl acetate to obtain the second aqueous phase and the second organic phase. Extract the second aqueous phase with 5 mL of ethyl acetate to obtain the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 32.8 mg of a pale yellow oily liquid product, characterized by NMR 1H NMR spectroscopy. 1 ¹H NMR (400M, CDCl₃): δ 6.72 (s, 2H), δ 2.53–2.36 (m, 4H), δ 1.74–1.64 (m, 4H), confirming that the final product obtained was 5,6,7,8-tetrahydro-1,4-naphthoquinone (6). TLC monitoring after the reaction at this temperature revealed the formation of byproducts near the product, resulting in a decreased yield and affecting separation.

[0064] The structural formula of 5,6,7,8-tetrahydronaphthol is shown in formula (7).

[0065]

[0066] Example 6

[0067] Preparation of 5,6,7,8-tetrahydro-1,4-naphthoquinone (6)

[0068] The specific operating steps are as follows: Take a dried 25 mL three-necked flask, add 74 mg of 5,6,7,8-tetrahydronaphthol and 10 mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to 0 °C, add 387 mg of iodophenyldiacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 3 hours. TLC monitoring showed that the reactants were almost completely reacted. Then, add 5 mL of ammonium chloride solution (25 °C, 6.95 mol / L) to the reaction system to quench the reaction. Add 5 mL of ethyl acetate and 5 mL of ammonium chloride solution to the obtained reaction product to extract the first aqueous phase and the first organic phase. Add 5 mL of ethyl acetate to the first aqueous phase to extract the second aqueous phase and the second organic phase. Add 5 mL of ethyl acetate to the second aqueous phase to extract the third aqueous phase and the third organic phase. Combine the first, second, and third organic phases and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 48.2 mg of a pale yellow oily liquid product, characterized by NMR 1H NMR spectroscopy. 1 1H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0069] Example 7

[0070] Preparation of 2,3-dihydro-1H-inden-4,7-dione (8)

[0071] The specific operating steps are as follows: Take a dried 25 mL three-necked flask, add 67 mg of 2,3-dihydro-1H-indene-4 alcohol (9) and 10 mL of anhydrous methanol, and purge with nitrogen three times. Cool the reaction system to 0 °C, add 387 mg of iodophenyl diacetic acid under a nitrogen atmosphere, and continue stirring at this temperature (600 rpm) for 6 hours. TLC monitoring showed that the reaction of the raw materials was complete. Then, add 5 mL of ammonium chloride solution (25 °C, 6.95 mol / L) to the reaction system to quench the reaction. Add 5 mL of ethyl acetate and 5 mL of ammonium chloride solution to the obtained reaction product to extract the first aqueous phase and the first organic phase. Add 5 mL of ethyl acetate to the first aqueous phase to extract the second aqueous phase and the second organic phase. Add 5 mL of ethyl acetate to the second aqueous phase to extract the third aqueous phase and the third organic phase. Combine the first organic phase, the second organic phase and the third organic phase, and evaporate to dryness to obtain the crude product. The residue in the crude product was separated by silica gel column chromatography using a 3.5 wt% ethyl acetate solution in petroleum ether as the eluent, ultimately yielding 52.3 mg of a pale yellow oily liquid product, characterized by NMR 1H NMR spectroscopy. 1¹H NMR (400M, CDCl₃): δ 6.69 (s, 2H), δ 2.85–2.81 (m, 4H), δ 2.02–1.98 (m, 2H). The final product was confirmed to be 2,3-dihydro-1H-inden-4,7-dione (8).

[0072]

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that potassium persulfate was used instead of iodophenyl diacetic acid, and 2-acetamido-5-methyl-p-benzoquinone (6) was not obtained.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that after purging with nitrogen three times, the reaction system was cooled to 0°C, while the reaction system was kept at room temperature (25°C), yielding 8.5 mg of a pale yellow oily liquid product, which was characterized by NMR 1H2O spectroscopy. 1 1H NMR (400M, CDCl3): δ6.72 (s, 2H), δ2.53-2.36 (m, 4H), δ1.74-1.64 (m, 4H), confirming that the final product obtained is 5,6,7,8-tetrahydro-1,4-naphthoquinone (6).

[0077] As can be seen from the above, the synthetic method proposed in this invention, using the phenol derivative shown in formula (2) as a raw material, is simple and efficient, and can prepare the p-benzoquinone derivative shown in formula (1) in one step, providing a new option for the synthesis of compounds containing quinone structures. Furthermore, the synthetic method proposed in this invention uses an alcohol solvent, which can be removed by low-temperature rotary evaporation. The entire process involves no dangerous operations, no byproducts, low experimental costs, and high yields.

[0078] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for synthesizing a p-benzoquinone derivative, characterized in that, include: The phenol derivative shown in formula (2) was oxidized with a high-valent iodine reagent to obtain the p-benzoquinone derivative shown in formula (1). The oxidation conditions included: the reaction temperature was equal to or lower than 10°C. Where n is an integer selected from 1 to 4.

2. The synthesis method according to claim 1, characterized in that, The oxidation conditions include: the raw material is dissolved in an organic solvent and the oxidation is carried out under an inert gas atmosphere; preferably, the organic solvent includes at least one of methanol and ethanol, more preferably methanol; preferably, the inert gas is selected from at least one of nitrogen, helium and argon.

3. The synthesis method according to claim 1 or 2, characterized in that, The oxidation conditions include: a reaction temperature of -15℃ to 10℃, preferably -10℃ to 5℃, and more preferably -5℃ to 0℃; And / or, the reaction time is 2 hours to 8 hours, preferably 3 hours to 6 hours.

4. The synthesis method according to any one of claims 1-3, characterized in that, The high-valent iodine reagent is a trivalent iodine reagent, preferably selected from at least one of dichloroiodobenzene and iodophenyldiacetic acid, more preferably iodophenyldiacetic acid; and / or, The molar ratio of the phenol derivative shown in formula (2) to the high-valent iodine reagent is 1:1 to 3.

5. The synthesis method according to any one of claims 1-4, characterized in that, The oxidation is carried out under stirring conditions. Preferably, the stirring speed is 500-1000 rpm, and more preferably 600-1000 rpm.

6. The synthesis method according to any one of claims 1-5, characterized in that, The synthesis method further includes adding a quenching agent after oxidation to obtain the reaction product. Preferably, the quenching agent includes an ammonium chloride solution with a concentration of 3 mol / L to 7 mol / L.

7. The synthesis method according to claim 6, characterized in that, The synthesis method further includes: adding an extraction solvent to the reaction product for extraction and separation to obtain an organic phase and an aqueous phase; drying the organic phase to obtain a crude product; separating the residue in the crude product to obtain the final product; preferably, the extraction solvent includes at least one of ethyl acetate, dichloromethane, and tetrahydrofuran; preferably, the extraction and separation is performed 1 to 5 times.

8. The synthesis method according to claim 7, characterized in that, The organic phase is dried by adding a desiccant; preferably, the desiccant includes at least one of anhydrous sodium sulfate and anhydrous magnesium chloride.

9. The synthesis method according to claim 7, characterized in that, The residues in the crude product are separated by column chromatography. Preferably, the column is packed with silica gel and the eluent is a petroleum ether solution of 2 wt% to 5 wt% ethyl acetate.

10. A p-benzoquinone derivative prepared by the synthetic method of any one of claims 1-9.

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