Intermediate and preparation method thereof, and synthesis method and application of bisindolylbenzene natural product

Abstract

The invention discloses an intermediate and a preparation method thereof, and a synthesis method and application of bisindolylbenzene natural products. The intermediate has the following structural formula: R1 and R2 are independently selected from H, hydroxyl, alkyl of C1-6, alkoxy of C1-6, benzyloxy and OTf group. The invention provides an intermediate with a novel structure, and the intermediate can be used for preparing a series of bisindolylbenzene natural products. The reaction is simple; the yield is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, and in particular to an intermediate, a preparation method thereof, a synthetic method and application of a bisindole benzene natural product. BACKGROUND

[0002] Bisindole alkaloids have two indole units as the core structure, and are an important subclass of indole alkaloids. Such compounds have diverse pharmacological properties, showing biological activities such as anti-tumor, antibacterial, and anti-malaria. In the past three decades, research groups such as Gloer, Nozawa, Gloer, Piggott, Kijjoa and Zhu have isolated a series of bisindole benzene alkaloids (structural formula shown below) from Aspergillus fungi. In 2023, Zhu's team confirmed that Asterriquinol D dimethylether, Kumbicins B-C and Petromurins C-D showed good selective anti-proliferative activity on acute myeloid leukemia (AML) cell line MV4-11. The research results show that these bisindole benzene compounds have important prospects in the development of anti-tumor candidate drugs.

[0003]

[0004] At present, the natural products isolated from Aspergillus fungi have the problems of great difficulty in separation and low separation yield. There is no report on the total synthesis of such bisindole benzene natural products. Therefore, it is necessary to develop a method for the total synthesis of bisindole benzene natural products. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present application provides an intermediate, from which a bisindole benzene natural product is prepared, with fewer synthesis steps and higher yield.

[0006] The second aspect of the present application further provides a preparation method of the intermediate.

[0007] The third aspect of the present application further provides a preparation method of a bisindole benzene natural product.

[0008] The fourth aspect of the present application further provides an application of a bisindole benzene compound.

[0009] According to the first aspect of the present application, an intermediate is provided, which has the following structural formula:

[0010]

[0011] wherein R1 and R2 are independently selected from H, hydroxyl.

[0012] According to a preferred embodiment of the present application, the intermediate has the following structural formula:

[0013]

[0014] According to the intermediate of the present application, at least the following advantages are achieved:

[0015] The present application provides a novel intermediate, which can be used to prepare a series of natural products of bis-indole benzene; the reaction is simple; and the yield is high.

[0016] The present application also provides a preparation method of the intermediate, which comprises the following steps:

[0017] The compound 11 and the compound 12 are subjected to a double Suzuki coupling reaction to obtain the intermediate;

[0018] Or, when the compound 12 is R selected from OR3, after the Suzuki coupling reaction, a step of removing the hydroxyl protecting group is further needed.

[0019] The structural formulae of the compound 11 and the compound 12 are as follows:

[0020]

[0021] R is selected from H or OR3, and R3 is a hydroxyl protecting group.

[0022] According to a preferred embodiment of the present application, the conditions of the Suzuki coupling reaction comprise a palladium catalyst, a base and a solvent.

[0023] According to a preferred embodiment of the present application, the palladium catalyst comprises at least one of bis(triphenylphosphine)palladium dichloride, tetrakis(triphenylphosphine)palladium, bis(benzonitrile)palladium, tris(benzonitrile)dipalladium, palladium chloride, palladium acetate, bis(acetonitrile)palladium dichloride and 1,1'-bis(diphenylphosphino)ferrocene]dichloropalladium.

[0024] According to a preferred embodiment of the present application, the base comprises at least one of sodium carbonate, potassium carbonate, lithium carbonate, cesium carbonate, potassium phosphate, sodium phosphate, silver oxide, silver carbonate, triethylamine, N,N-diisopropylethylamine and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0025] According to a preferred embodiment of the present application, the step of removing the hydroxyl protecting group comprises adding Pd / C catalyst to react under H2 atmosphere.

[0026] According to a preferred embodiment of the present application, the compound 11 is prepared by the following method:

[0027] The compound 10, dimethyl sulfate, a base and a solvent are mixed to carry out methylation reaction to obtain the compound 19.

[0028] The compound 10 has the following structural formula:

[0029]

[0030] According to a preferred embodiment of the present application, the compound 10 can be obtained by commercial purchase or by the following method:

[0031] The compound 9, dimethyl sulfate, potassium carbonate are mixed to carry out reaction to obtain the compound 10.

[0032] The compound 9 has the following structural formula:

[0033]

[0034] The third aspect of the present application provides a method for preparing the diindole benzene natural product Asterriquinol D dimethylether and Kumbicin A, comprising the following steps:

[0035] The intermediate in the first aspect of the present application and an acidic reagent are reacted to remove the Boc protecting group to obtain the compound.

[0036] According to a preferred embodiment of the present application, the acidic reagent comprises at least one of hydrochloric acid, trifluoroacetic acid (TFA), dilute sulfuric acid, trimethylsilyl trifluoromethanesulfonate (TMSOTf) or trimethylsilyl iodide (TMSI).

[0037] The fourth aspect of the present application further provides a method for preparing the diindole benzene natural product Candidusin D and Petromurin D, comprising the following steps:

[0038] S1, the intermediate, dimethyl sulfate, a base and a solvent are mixed to carry out methylation reaction to obtain the compound 19.

[0039] S2, the compound 19 is further subjected to Boc removal to obtain Petromurin D or Candidusin D.

[0040] The intermediate is selected from the intermediate I-2 in the first aspect of the present application.

[0041] The compound 19 has the following structural formula:

[0042]

[0043] According to a preferred embodiment of the present application, in step S1, the present application controls the molar ratio of the intermediate and dimethyl sulfate to achieve the degree of methylation, for example, when the molar ratio of the intermediate and dimethyl sulfate is 1:1.1, only one hydroxyl group on the benzene ring in compound 19 is methylated; when the molar ratio of the intermediate and dimethyl sulfate is 1:2.5, both of the two hydroxyl groups on the benzene ring in compound 19 are methylated.

[0044] According to a preferred embodiment of the present application, in step S1, the base includes at least one of potassium carbonate, sodium carbonate, cesium carbonate, potassium phosphate, sodium phosphate, sodium hydroxide, potassium hydroxide, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0045] According to a preferred embodiment of the present application, in step S1, the solvent includes at least one of acetone, tetrahydrofuran, 1,4-dioxane, acetonitrile, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0046] According to a preferred embodiment of the present application, in step S2, the compound 19 is reacted with an acidic reagent to remove the Boc group.

[0047] According to a preferred embodiment of the present application, the acidic reagent includes at least one of hydrochloric acid, trifluoroacetic acid (TFA), dilute sulfuric acid, trimethylsilyl triflate (TMSOTf), or trimethylsilyl iodide (TMSI).

[0048] According to a fifth aspect of the present application, a method for preparing the biindole benzene natural product Kumbicin B and Petromurin C is provided, which includes the following steps:

[0049] (1) reacting the intermediate, N-phenylbis(trifluoromethanesulfonimide), 4-dimethylaminopyridine, and a solvent to obtain compound 21;

[0050] (2) subjecting the compound 21 to a hydrogenolysis reaction to obtain compound 22;

[0051] (3) removing the Boc group from the compound 22 to obtain Petromurin C;

[0052] or, subjecting the compound 22, dimethyl sulfate, a base, and a solvent to a methylation reaction to obtain compound 23; and then removing the Boc group from the compound 23 to obtain Kumbicin B;

[0053] The intermediate is selected from the intermediate I-2 according to the first aspect of the present application.

[0054] The structural formula of the compound 21, the compound 22 and the compound 23 is as follows:

[0055]

[0056] According to a preferred embodiment of the present application, in step (2), the hydrogenolysis reaction is carried out under the condition of palladium-carbon catalyst, hydrogen and base.

[0057] According to a preferred embodiment of the present application, in step (3), the compound 22 is reacted with acetyl chloride in an alcohol solvent to remove the Boc group.

[0058] According to a preferred embodiment of the present application, in step (3), the compound 23 is reacted with acetyl chloride in an alcohol solvent to remove the Boc group.

[0059] The sixth aspect of the present application provides a use of a biindolylbenzene compound in the preparation of an α-glucosidase inhibitor, wherein the biindolylbenzene compound is selected from the following structural formula II:

[0060]

[0061] wherein, the R 1 , R 2 are independently selected from H, OH, C 1～6 alkyl, C 1～6 alkoxy, benzyloxy, OTf group;

[0062] R 3 is selected from H and Boc group.

[0063] According to a preferred embodiment of the present application, the R 1 , R 2 are independently selected from H, OH, C 1～3 alkoxy, benzyloxy, OTf group.

[0064] According to a preferred embodiment of the present application, the biindolylbenzene compound is selected from the following structural formula:

[0065]

[0066] According to the embodiments of the present application, the biindolylbenzene compound has at least the following beneficial effects:

[0067] The present application finds that the biindolylbenzene compound has significant α-glucosidase inhibitory activity, and tests the specific half-inhibitory concentration (IC 50The type and mechanism of the inhibition of the double indole benzene compound on α-glucosidase are revealed by kinetic study, circular dichroism and molecular docking technology. The double indole benzene compound is expected to be used for development of a new type of α-glucosidase inhibitor.

[0068] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0069] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0070] Figure 1 Figure is the graph of the inhibition activity and mechanism of intermediate I-2 of the present application on α-glucosidase. DETAILED DESCRIPTION

[0071] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

[0072] The reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field unless otherwise specified.

[0073] Example 1

[0074] This example provides an intermediate I-1, and the preparation method is as follows:

[0075] Synthesis of compound 10:

[0076]

[0077] Compound 9 (2 g, 14.07 mmol) and potassium carbonate were dissolved in acetone (30 mL) under the protection of N2, Me2SO4 (8.01 mL, 84.44 mmol) was added at room temperature, and after stirring at 60°C overnight, it was concentrated under vacuum. Ethyl acetate was added for dissolution, washed with saturated brine, and dried with anhydrous sodium sulfate. After the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain compound 10 (2.23 g, 80%).

[0078] The nuclear magnetic hydrogen spectrum and carbon spectrum data of compound 10 are as follows:

[0079] 1 H NMR (500 MHz, DMSO-d6) δ 6.71 (s, 2H), 3.72 (s, 12H).

[0080] 13C NMR (126 MHz, DMSO-d6) δ 143.25, 102.01, 57.08.

[0081] Synthesis of compound 11:

[0082]

[0083] Compound 10 (1 g, 5.05 mmol) was dissolved in dry THF (10 mL) under N2protection, TMEDA (3.03 mL, 20.2 mmol) was added at room temperature, after cooling to -78 °C, nBuLi (8.08 mL, 20.2 mmol, 2.5 M in THF) was added dropwise slowly. After the reaction was stirred at -78 °C for half an hour, it was slowly warmed to room temperature and stirred for one hour, then cooled to -78 °C again, I2(5.13 g, 20.2 mmol) in dry THF (30 mL) was added dropwise slowly to the above reaction system. After stirring at room temperature for 12 hours, the reaction was quenched with saturated sodium sulfite. Diluted with ethyl acetate, washed with saturated brine, dried with sodium sulfate, the organic phase was concentrated under reduced pressure, the residue was separated on a silica gel column to obtain compound 11 (2.84 g, 88%).

[0084] The hydrogen spectrum and carbon spectrum data of compound 11 are as follows:

[0085] 1 H NMR (500 MHz, DMSO-d6) δ 3.73 (s, 12H).

[0086] 13 C NMR (126 MHz, DMSO-d6) δ 149.77, 92.78, 60.86.

[0087] Synthesis of intermediate 1-1

[0088]

[0089] Compound 11 (150 mg, 0.33 mmol), compound 12 (343.22 mg, 0.99 mmol) and bis(triphenylphosphine)palladium dichloride (23.4 mg, 0.03 mmol) were dissolved in degassed THF / H2O / EtOH (7:2:3 mL) and Na2CO3(0.53 mL, 0.53 mmol, 1 M in H2O) solvents under N2protection. After stirring at 80 °C overnight, the reaction was quenched with saturated sodium sulfite. Diluted with ethyl acetate, washed with saturated brine, dried with sodium sulfate, the organic phase was concentrated under reduced pressure, the residue was separated on a silica gel column to obtain intermediate I-1 (114.11 mg, 55%).

[0090] The nuclear magnetic hydrogen spectrum and carbon spectrum data of intermediate I-1 are as follows:

[0091] 1 H NMR (400 MHz, DMSO-d6) δ 8.14 (d, J = 8.3 Hz, 2H), 7.76 (s, 2H), 7.43 - 7.37 (m, 4H), 7.30 - 7.25 (m, 2H), 3.52 (s, 12H), 1.68 (s, 18H).

[0092] 13 C NMR (101 MHz, DMSO-d6) δ 149.58, 148.13, 134.78, 130.59, 125.40, 124.81, 123.21, 121.68, 121.17, 115.14, 113.57, 84.58, 61.24, 28.20.

[0093] Example 2

[0094] This example provides an intermediate I-2; the preparation method is as follows:

[0095]

[0096] Synthesis of compound 15:

[0097] Compound 14 (1 g, 4.48 mmol) was dissolved in DMF (10 mL), KOH (1.19 g, 17.91 mmol) and H2O (2.5 mL) were added in turn at room temperature, and after stirring to dissolve, I2 (1.7 g, 6.72 mmol) in DMF (15 mL) was added. The reaction was stirred at room temperature overnight, and the reaction was detected by TLC plate. Diluted with water, extracted with ethyl acetate. The combined organic phase was washed with saturated sodium sulfite, saturated brine in turn, dried over sodium sulfate, and concentrated under reduced pressure, and the residue was directly used for the next reaction.

[0098] 1 H NMR (500 MHz, DMSO-d6) δ 11.42 (d, J = 2.6 Hz, 1H), 7.52 - 7.48 (m, 3H), 7.40 (t, J = 7.6 Hz, 2H), 7.33 (dd, J = 8.1, 2.7 Hz, 2H), 6.89 (dd, J = 8.8, 2.4 Hz, 1H), 6.83 (d, J = 2.4 Hz, 1H), 5.13 (s, 2H).

[0099] 13C NMR (126 MHz, DMSO-d6) δ 153.66, 138.05, 131.49, 130.64, 130.19, 128.84, 128.12, 113.60, 113.28, 103.17, 70.16, 55.96.

[0100] The product of previous step was dissolved in dichloromethane (15 mL) and DMAP (139.95 mg, 1.15 mmol), Boc20 (3.23 mL, 14.32 mmol) were added sequentially at room temperature. The reaction was stirred at room temperature overnight and the completion of the reaction was monitored by TLC plate. It was diluted with dichloromethane, washed with saturated brine, dried over sodium sulfate and the organic phase was concentrated under reduced pressure. The residue was separated on silica gel column to get compound 15 (989.43 mg, 77%).

[0101] 1 H NMR (500 MHz, CDCl3) δ 8.04 (s, 1H), 7.73 (s, 1H), 7.51 (d, J = 7.1 Hz, 2H), 7.43 (t, J = 7.6 Hz, 2H), 7.37 (t, J = 7.3 Hz, 1H), 7.07 (dd, J = 9.0, 2.5 Hz, 1H), 6.97 (d, J = 2.5 Hz, 1H), 5.17 (s, 2H), 1.68 (s, 9H).

[0102] 13 C NMR (126 MHz, CDCl3) δ 155.68, 137.00, 132.99, 130.64, 128.61, 128.03, 127.71, 116.03, 115.05, 105.19, 84.21, 70.62, 65.18, 28.17.

[0103] Synthesis of compound 16

[0104] Compound 15 (2 g, 4.45 mmol) was dissolved in dry THF (20 mL) and cooled to -10 °C under N2. Isopropyl magnesium chloride-lithium chloride (6.85 mL, 8.9 mmol, 1.3 M in THF) was added drop wise slowly. The reaction was stirred at -10 °C for half an hour and then methoxyboronic acid pinacol ester (2.19 mL, 13.35 mmol) was added drop wise slowly and allowed to warm to room temperature. The reaction was stirred at room temperature for 12 h and quenched with saturated ammonium chloride. It was diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate and the organic phase was concentrated under reduced pressure. The residue was separated on silica gel column to get compound 16 (1.32 g, 66%).

[0105] 1 H NMR (500 MHz, CDC13 ) δ 8.06 (d, J = 9.0 Hz, 1H), 8.00 (s, 1H), 7.58 (d, J = 2.6 Hz, 1H), 7.53 (d, J = 7.1 Hz, 2H), 7.42 (t, J = 7.5 Hz, 2H), 7.38 - 7.32 (m, 1H), 7.02 (dd, J = 8.9, 2.6 Hz, 1H), 5.17 (s, 2H), 1.67 (s, 9H), 1.39 (s, 12H).

[0106] 13 C NMR (126 MHz, CDC13 ) δ 155.24, 149.35, 137.52, 135.75, 134.48, 131.01, 128.55, 127.87, 127.77, 115.48, 113.28, 106.99, 83.75, 83.34, 70.62, 28.21, 24.92.

[0107] Synthesis of compound 17

[0108] Compound 16 (760 mg, 1.69 mmol), compound 11 (1.9 g, 4.22 mmol) and bis(triphenylphosphine)palladium dichloride (118.54 mg, 0.17 mmol) were dissolved in degassed THF / H20 / EtOH (7:2:3 mL) and Na2C03 (2.7 mL, 2.7 mmol, 1 M in H20) solvents under N2protection. After stirring at 80 °C overnight, the reaction was quenched with saturated sodium sulfite. Diluted with ethyl acetate, washed with saturated brine, dried with sodium sulfate, the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to give compound 17 (781.68 mg, 55%).

[0109] The data of the nuclear magnetic hydrogen spectrum and carbon spectrum of compound 17 are as follows:

[0110] 1 H NMR (500 MHz, CDC13 ) δ 8.06 (d, J = 9.0 Hz, 1H), 8.00 (s, 1H), 7.58 (d, J = 2.6 Hz, 1H), 7.53 (d, J = 7.1 Hz, 2H), 7.42 (t, J = 7.5 Hz, 2H), 7.38 - 7.32 (m, 1H), 7.02 (dd, J = 8.9, 2.6 Hz, 1H), 5.17 (s, 2H), 1.67 (s, 9H), 1.39 (s, 12H).

[0111] 13C NMR (126 MHz, CDC13) δ 155.00, 149.77, 148.12, 137.32, 131.44, 130.11, 128.51, 127.84, 127.62, 125.93, 121.64, 115.76, 113.64, 113.29, 105.21, 83.65, 70.57, 61.14, 28.29.

[0112] Synthesis of intermediate 1-2

[0113]

[0114] Compound 17 (800 mg, 0.95 mmol) was dissolved in ethyl acetate (10 mL) under the protection of H2. Pd / C (50.62 mg, 0.48 mmol), and trichloroethane (193.67 mL, 2.09 mmol) were added successively at room temperature. The reaction was stirred at room temperature overnight, and the reaction was detected by TLC plate. The solid was removed by filtration, diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate, and then the organic phase was concentrated under reduced pressure. The residue was separated by silica gel column to obtain intermediate 1-2 (408 mg, 65%).

[0115] The nuclear magnetic hydrogen spectrum and carbon spectrum data of intermediate 1-2 are as follows:

[0116] 1 H NMR (500 MHz, DMSO-d6) δ 9.20 (s, 2H), 7.90 (d, J = 8.9 Hz, 2H), 7.67 (s, 2H), 6.83 (dd, J = 8.9, 2.4 Hz, 2H), 6.70 (d, J = 2.4 Hz, 2H), 3.53 (s, 12H), 1.66 (s, 18H).

[0117] 13 C NMR (126 MHz, DMSO-d6) δ 153.74, 149.58, 148.09, 131.81, 128.54, 125.66, 121.79, 115.75, 113.87, 113.20, 105.65, 84.10, 61.28, 28.22.

[0118] Example 3

[0119] This example provides a preparation method of a bisindole benzene natural product Asterriquinol D dimethyl ether, comprising the following steps:

[0120]

[0121] Intermediate 1-1 of Example 1 (100 mg, 0.16 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). The reaction was stirred at room temperature and checked for completion using TLC plate. The reaction was neutralized with saturated sodium bicarbonate, diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate and the organic phase was concentrated under reduced pressure. The residue was separated on a silica gel column to obtain natural product Asterriquinol D dimethyl ether (48 mg, 70%).

[0122] The nuclear magnetic hydrogen and carbon spectrum data of natural product Asterriquinol D dimethyl ether are as follows:

[0123] 1 H NMR (400 MHz, DMSO-d6) δ 11.30 (s, 2H), 7.49 - 7.40 (m, 6H), 7.12 (t, J = 8.1 Hz, 2H), 7.03 - 6.99 (m, 2H), 3.43 (s, 12H).

[0124] 13 C NMR (101 MHz, DMSO-d6) δ 147.66, 135.91, 127.07, 125.23, 122.18, 120.79, 120.27, 118.70, 111.38, 106.96, 60.31.

[0125] Example 4

[0126] This example provides a method for preparing a bis-indole benzene natural product, Kumbicin A, the reaction equation and steps are as follows:

[0127]

[0128] Intermediate 1-2 (25 mg, 0.038 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). The reaction was stirred at room temperature and checked for completion using TLC plate. The reaction was neutralized with saturated sodium bicarbonate, diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate and the organic phase was concentrated under reduced pressure. The residue was separated on a silica gel column to obtain natural product Kumbicin A (13.5 mg, 77%).

[0129] The nuclear magnetic hydrogen and carbon spectrum data of natural product Kumbicin A are as follows:

[0130] 1H NMR (600 MHz, DMSO-d6) δ 11.03 (s, 2H), 8.66 (s, 2H), 7.29 (d, J = 74.8 Hz, 4H), 6.69 (d, J = 58.6 Hz, 4H), 3.43 (s, 12H).

[0131] 13 C NMR (151 MHz, DMSO-d6) δ 150.46, 147.60, 130.39, 127.95, 125.51, 122.28, 111.58, 111.15, 106.18, 104.20, 60.30.

[0132] Example 5

[0133] This example provides a method for preparing a biindole benzene natural product, Petromurin D, according to the following steps:

[0134] Synthesis of compound 19:

[0135]

[0136] Under the protection of N2, intermediate I-2 (150 mg, 0.23 mmol), potassium carbonate (31.38 mg, 0.23 mmol) were dissolved in acetone (2 mL), Me2SO4 (21.56 ul, 0.23 mmol) was added at room temperature, and stirred at 60°C overnight, then concentrated under vacuum. Dissolved with ethyl acetate, washed with saturated brine, and dried with anhydrous sodium sulfate. After the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain compound 19 (91.92 mg, 60%).

[0137] The nuclear magnetic hydrogen spectrum and carbon spectrum data of compound 19 are as follows:

[0138] 1 H NMR (600 MHz, DMSO-d6) δ 11.03 (s, 2H), 8.66 (s, 2H), 7.29 (d, J = 74.8 Hz, 4H), 6.69 (d, J = 58.6 Hz, 4H), 3.43 (s, 12H).

[0139] 13C NMR (151 MHz, DMSO-d6) δ 155.94, 153.72, 149.54, 148.09, 131.76, 131.53, 129.42, 126.10, 125.69, 121.88, 121.45, 115.79, 113.87, 113.38, 113.18, 105.78, 103.71, 84.39, 84.11, 61.26, 55.83, 28.22.

[0140] Synthesis of Petromurin D

[0141]

[0142] Compound 19 (35 mg, 0.052 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). The reaction was stirred at room temperature and checked for completion using TLC plate. The reaction was neutralized with saturated sodium bicarbonate, diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate and the organic phase was concentrated under reduced pressure. The residue was separated on a silica gel column to obtain natural product 8 (17.23 mg, 88%).

[0143] 1 H NMR (500 MHz, DMSO-d6) δ 11.26 - 11.16 (m, 1H), 11.12 - 10.97 (m, 1H), 8.61 (s, 1H), 7.43 (d, J = 2.6 Hz, 1H), 7.38 - 7.31 (m, 2H), 7.22 (d, J = 8.5 Hz, 1H), 6.87 (d, J = 2.5 Hz, 1H), 6.80 - 6.72 (m, 2H), 6.64 (dd, J = 8.6, 2.5 Hz, 1H), 3.72 (s, 3H), 3.45 (d, J = 10.3 Hz, 12H).

[0144] 13 C NMR (126 MHz, DMSO-d6) δ 153.13, 150.43, 147.57, 131.03, 130.38, 127.87, 127.43, 125.94, 125.56, 122.41, 121.89, 111.96, 111.56, 111.13, 110.88, 106.77, 106.08, 104.26, 101.96, 60.32, 60.24, 55.23.

[0145] Example 6

[0146] This example provides a method for preparing a bis-indole benzene natural product Candidusin D, the steps of which are as follows:

[0147]

[0148] Intermediate I-2 (100 mg, 0.15 mmol), potassium carbonate (21.92 mg, 0.15 mmol) were dissolved in acetone (2 mL) under the protection of N2, Me2SO4 (35.93 ul, 0.38 mmol) was added at room temperature, after stirring at 60 °C overnight, concentrated under vacuum. Dissolved with ethyl acetate, washed with saturated brine, dried with anhydrous sodium sulfate. After the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain compound 20 (67.16 mg, 65%).

[0149] 1 H NMR (500 MHz, DMSO-d6) δ 8.02 (d, J = 9.0 Hz, 2H), 7.72 (s, 2H), 7.01 (dd, J = 9.0, 2.6 Hz, 2H), 6.87 (d, J = 2.6 Hz, 2H), 3.76 (s, 6H), 3.55 (s, 12H), 1.67 (s, 18H).

[0150] 13 C NMR (126 MHz, DMSO-d6) δ 155.93, 149.49, 148.09, 131.50, 126.12, 121.55, 115.84, 113.42, 113.31, 103.85, 84.37, 61.24, 55.84, 28.20.

[0151] Synthesis of Candidusin D:

[0152]

[0153] Compound 20 (50 mg, 0.073 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). Stirred at room temperature, the reaction was detected to be complete by TLC plate. Neutralized the reaction with saturated sodium bicarbonate, diluted with ethyl acetate, washed with saturated brine, dried with sodium sulfate, the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain natural product Candidusin D (29.96 mg, 84%).

[0154] The nuclear magnetic hydrogen spectrum and carbon spectrum data of natural product Candidusin D are as follows:

[0155] 1H NMR (500 MHz, DMSO-d6) δ 11.16 (s, 2H), 7.44 (d, J = 2.5 Hz, 2H), 7.33 (d, J = 8.7 Hz, 2H), 6.89 (d, J = 2.4 Hz, 2H), 6.78 (dd, J = 8.8, 2.5 Hz, 2H), 3.73 (s, 6H), 3.46 (s, 12H).

[0156] 13 C NMR (126 MHz, DMSO-d6) δ 153.20, 147.63, 131.10, 127.47, 126.06, 122.10, 112.00, 110.94, 106.80, 102.17, 60.33, 55.31.

[0157] Example 7

[0158] This example provides a method for preparing a biindole benzene natural product, Petromurin C, according to the following steps:

[0159]

[0160] Intermediate I-2 (450 mg, 0.68 mmol) was dissolved in dichloromethane (9 mL) under N2protection, DMAP (249.62 mg, 2.04 mmol) was added at room temperature, and stirred for 5 minutes, then Tf2Nph (243.31 mg, 0.68 mmol) was added at room temperature. The reaction was stirred at room temperature, and the completion of the reaction was detected by TLC plate. Diluted with dichloromethane, washed with saturated brine, dried with sodium sulfate, and concentrated under reduced pressure. The residue was separated by silica gel column to obtain compound 21 (329.37 mg, 61%).

[0161] 1 H NMR (500 MHz, DMSO-d6) δ 9.20 (s, 1H), 8.27 (d, J = 9.9 Hz, 1H), 7.97 (s, 1H), 7.90 (d, J = 8.9 Hz, 1H), 7.66 (s, 1H), 7.51 (d, J = 7.5 Hz, 2H), 6.83 (dd, J = 8.9, 2.4 Hz, 1H), 6.72 (d, J = 2.4 Hz, 1H), 3.54 (d, J = 5.0 Hz, 12H), 1.68 (d, J = 15.2 Hz, 18H).

[0162] 13C NMR (126 MHz, DMSO-d6) δ 153.72, 149.56, 149.11, 148.16, 147.90, 145.42, 133.82, 131.69, 131.27, 128.55, 128.33, 125.72, 122.33, 120.37, 117.88, 116.84, 115.73, 113.91, 113.29, 113.05, 105.78, 85.52, 84.14, 61.25, 61.19, 28.21, 28.10.

[0163] Synthesis of compound 22:

[0164]

[0165] Compound 21 (250 mg, 0.32 mmol) was dissolved in ethyl acetate (3 mL) under the protection of H2. Pd / C (6.71 mg, 0.063 mmol), triethylamine (131.5 ul, 0.95 mmol) were added successively at room temperature. The reaction was stirred at room temperature overnight, and the reaction was detected by TLC plate. The solid was removed by filtration, diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate, and then the organic phase was concentrated under reduced pressure. The residue was separated by silica gel column to obtain compound 22 (103.69 mg, 51%).

[0166] 1 H NMR (500 MHz, DMSO-d6) δ 9.20 (s, 1H), 8.14 (d, J = 8.3 Hz, 1H), 7.90 (d, J = 8.9 Hz, 1H), 7.77 (s, 1H), 7.67 (s, 1H), 7.40 (d, J = 7.5 Hz, 2H), 7.28 (s, 1H), 6.83 (dd, J = 8.9, 2.4 Hz, 1H), 6.72 (d, J = 2.4 Hz, 1H), 3.53 (d, J = 2.3 Hz, 12H), 1.67 (d, J = 12.0 Hz, 18H).

[0167] 13 C NMR (126 MHz, DMSO-d6) δ 153.73, 149.58, 148.11, 134.76, 131.79, 130.60, 130.00, 125.66, 125.42, 124.80, 123.37, 123.22, 121.94, 121.55, 121.11, 115.73, 115.16, 113.87, 113.56, 113.19, 105.71, 84.57, 84.09, 61.26, 28.21, 28.19.

[0168] Synthesis of natural product Petromurin C:

[0169]

[0170] Compound 22 (20 mg, 0.031 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). The reaction was stirred at room temperature and checked for completion using TLC plate. The reaction was neutralized with saturated sodium bicarbonate. The organic phase was dried over sodium sulfate and concentrated under reduced pressure. The residue was separated on a silica gel column to obtain natural product 7 (10.47 mg, 76%).

[0171] 1 H NMR (500 MHz, DMSO-d6) δ 11.34 (d, J = 2.4 Hz, 1H), 11.03 (d, J = 2.6 Hz, 1H), 8.61 (s, 1H), 7.48 - 7.43 (m, 2H), 7.40 (d, J = 8.0 Hz, 1H), 7.35 (d, J = 2.5 Hz, 1H), 7.22 (d, J = 8.6 Hz, 1H), 7.12 (t, J = 6.9 Hz, 1H), 7.01 (t, J = 7.4 Hz, 1H), 6.75 (d, J = 2.3 Hz, 1H), 6.64 (dd, J = 8.6, 2.3 Hz, 1H), 3.43 (s, 12H).

[0172] 13 C NMR (126 MHz, DMSO-d6) δ 150.44, 147.62, 147.60, 135.88, 130.38, 127.90, 127.07, 125.53, 125.19, 122.54, 121.90, 120.76, 120.21, 118.68, 111.57, 111.39, 111.14, 106.95, 106.09, 104.22, 60.33, 60.28.

[0173] Example 8

[0174] This example provides a method for preparing the bis-indole benzene natural product Kumbicin B, the steps of which are as follows:

[0175]

[0176] Compound 22 (80 mg, 0.12 mmol), potassium carbonate (17.15 mg, 0.12 mmol) were dissolved in acetone (2 mL) under N2, Me2SO4(17.67 ul, 0.19 mmol) was added at room temperature, after stirring at 60 °C overnight, concentrated under vacuum. Diluted with ethyl acetate, washed with saturated brine, dried over anhydrous sodium sulfate. The organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain compound 23 (69.48 mg, 85%).

[0177] 1 H NMR (500 MHz, DMSO-d6) δ 8.14 (d, J = 8.3 Hz, 1H), 8.02 (d, J = 9.0 Hz, 1H), 7.77 (s, 1H), 7.72 (s, 1H), 7.43 (d, J = 7.8 Hz, 1H), 7.39 (t, J = 7.7 Hz, 1H), 7.27 (t, J = 7.9 Hz, 1H), 7.01 (dd, J = 9.0, 2.6 Hz, 1H), 6.86 (d, J = 2.6 Hz, 1H), 3.76 (s, 3H), 3.54 (d, J = 10.5 Hz, 12H), 1.68 (d, J = 7.1 Hz, 18H).

[0178] 13 C NMR (126 MHz, DMSO-d6) δ 155.94, 149.54, 148.11, 134.78, 131.52, 130.56, 129.41, 126.08, 125.43, 124.80, 123.20, 121.62, 121.25, 115.86, 115.13, 113.55, 113.39, 103.73, 84.57, 84.37, 61.24, 55.83, 28.20.

[0179] Synthesis of natural product Kumbicin B:

[0180]

[0181] Compound 23 (50 mg, 0.076 mmol) was dissolved in methanolic hydrochloric acid solution (generated in situ from 1 mL acetyl chloride and 2.5 mL methanol). Stirred at room temperature, the reaction was checked by TLC plate. Neutralized with saturated sodium bicarbonate. Diluted with ethyl acetate, washed with saturated brine, dried over sodium sulfate, the organic phase was concentrated under reduced pressure, the residue was separated by silica gel column to obtain natural product Kumbicin B (22.30 mg, 64%).

[0182] 1H NMR (500 MHz, DMSO-d6) δ 11.30 (d, J = 2.5 Hz, 1H), 11.15 (d, J = 2.6 Hz, 1H), 7.47 (d, J = 2.4 Hz, 1H), 7.45 - 7.42 (m, 3H), 7.33 (d, J = 8.7 Hz, 1H), 7.12 (t, J = 7.5 Hz, 1H), 7.01 (t, J = 7.3 Hz, 1H), 6.88 (d, J = 2.4 Hz, 1H), 6.78 (dd, J = 8.7, 2.5 Hz, 1H), 3.72 (s, 3H), 3.45 (d, J = 11.5 Hz, 12H).

[0183] 13 C NMR (126 MHz, DMSO-d6) δ 153.14, 147.60, 147.59, 135.87, 131.02, 127.41, 127.01, 125.96, 125.24, 122.15, 122.03, 120.77, 120.30, 118.67, 111.94, 111.36, 110.89, 106.91, 106.73, 102.02, 60.29, 60.26, 55.23.

[0184] Study on the inhibitory activity and mechanism of action of bis-indole benzene compounds on α-glucosidase

[0185] (1) Test method of the inhibitory activity of bis-indole benzene compounds on α-glucosidase

[0186] In 130 μL of 0.1 mol / L phosphate buffer (PBS), 10 μL of the test compound and 10 μL of α-glucosidase (2 U / mL) were added in turn, and after incubation at 37°C for 10 minutes, 50 μL of p-nitrophenyl-α-D-glucopyranoside (p-NPG, 1 mM) was added. The inhibitory activity of α-glucosidase was calculated by monitoring the absorbance change at 405 nm. The final concentrations of α-glucosidase and p-NPG in the experimental system were 0.1 U / mL and 0.25 mM, respectively. The results are shown in Table 1.

[0187] Table 1

[0188]

[0189]

[0190] (2) Mechanism of action of the bis-indole benzene natural product of the application

[0191] Enzyme kinetics experiment: the concentration of p-NPG was fixed at 0.25 mM, and the concentration gradient of α-glucosidase was set to 0.075-0.15 U / mL

[0192] Substrate kinetics experiment: The concentration of α-glucosidase was fixed at 0.1 U / mL, and the concentration gradient of p-NPG was set at 0.25-1 mM.

[0193] The test concentration of intermediate I-2 was set at 0, 6, 9, and 12 μM.

[0194] (3) Circular dichroism analysis method for the interaction of intermediate I-2 and α-glucosidase

[0195] The measurement wavelength range of circular dichroism (CD) was 200-250 nm. 10 μL of intermediate I-2 was added to a solution containing 190 μL of α-glucosidase (7 μM), and the mixture was incubated at room temperature for 5 min. The molar ratio of α-glucosidase to intermediate I-2 was set at 1:0, 1:4, and 1:8, respectively.

[0196] (4) Molecular docking study method for the interaction of intermediate I-2 and α-glucosidase

[0197] The molecular docking study of intermediate I-2 and α-glucosidase was performed using SYBYL software. First, the molecular structure of intermediate I-2 was analyzed and optimized by Gasteiger-Hückel charge model. The obtained α-glucosidase homologous protein was refined by steps such as water molecule removal, hydrogen atom addition, and charge calculation. Then, the active pocket of α-glucosidase was constructed by using an automatic method. Finally, the docking operation of intermediate I-2 and α-glucosidase was performed by using Surflex-Dock geometric docking mode, and the interaction results were obtained.

[0198] The results are shown in (A) and (B) of FIG. 1: Figure 1 The kinetic study showed that intermediate I-2 was a reversible non-competitive α-glucosidase inhibitor. The inhibition constant (Ki) of intermediate I-2 on α-glucosidase was 1.401 μM. As shown in (C) of FIG. 1, the binding interaction between the bis-indole benzoid compound and α-glucosidase and the effect on the enzyme structure were further explored by circular dichroism and molecular docking study. As shown in (D) of FIG. 1, the results showed that this binding interaction mainly through hydrogen bond and hydrophobic interaction induced significant conformational changes and microenvironment modification of the secondary structure of α-glucosidase, thereby affecting its catalytic activity. Figure 1 Figure 1

[0199] The above is described in detail in combination with the embodiments of the present application, but the present application is not limited to the above-described embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the purpose of the present application.​​

Claims

1. An intermediate, characterized in that, It has the following structural formula: R1 and R2 are independently selected from H and hydroxyl groups.

2. The intermediate according to claim 1, characterized in that, The intermediate has the following structural formula:

3. A method for preparing the intermediate as described in claim 1 or 2, characterized in that, Includes the following steps: The compound 11 and compound 12 were subjected to a double Suzuki coupling reaction to obtain the product. Alternatively, when R in compound 12 is selected from OR3, a dehydroxyl protecting group step is required after the Suzuki coupling reaction. The structural formulas of compounds 11 and 12 are as follows: R is selected from H or OR3, where R3 is a hydroxyl protecting group.

4. A method for preparing the bisindophenyl natural products Asterriquinol D dimethyl ether and Kumbicin A, characterized in that, Includes the following steps: The intermediate described in claim 1 is reacted with an acidic reagent to remove the Boc protecting group, thus obtaining the final product.

5. A method for preparing the bisindophenyl natural products Candidusin D and Petromurin D, characterized in that, Includes the following steps: S1. The intermediate, dimethyl sulfate, base, and solvent are mixed and subjected to a methylation reaction to obtain compound 19. S2. Then, remove the Boc group from compound 19 to obtain Petromurin D or Candidusin D; The intermediate is selected from intermediate I-2 as described in claim 2; The structural formula of compound 19 is as follows:

6. A method for preparing the bisindophenyl natural products Kumbicin B and Petromurin C, characterized in that, Includes the following steps: (1) The intermediate, N-phenylbis(trifluoromethanesulfonylimide), 4-dimethylaminopyridine and solvent were reacted to obtain compound 21; (2) Compound 21 is subjected to hydrogenolysis to obtain compound 22; (3) The Boc group of compound 22 was removed to obtain Petromurin C; Alternatively, compound 22, dimethyl sulfate, a base, and a solvent are mixed and subjected to a methylation reaction to obtain compound 23; Compound 23 was then de-Boc-treated to obtain Kumbicin B. The intermediate is selected from intermediate I-2 as described in claim 2; The structural formulas of compounds 21, 22 and 23 are as follows:

7. The preparation method according to claim 6, characterized in that, In step (2), the conditions for the hydrogenolysis reaction include a palladium catalyst on carbon, hydrogen gas, and an alkali.

8. The application of a bisindolebenzene compound in the preparation of α-glucosidase inhibitors, characterized in that, The bisindolebenzene compound is selected from the structural formula shown in Formula II: Wherein, the R 1 R 2 Independently selected from H, OH, C 1～6 alkyl, C 1～6 alkoxy, benzyloxy, OTf group; R 3 Selected from H and Boc bases.

9. The application according to claim 8, characterized in that, R 1 R 2 Independently selected from H, OH, C 1～3 The alkoxy, benzyloxy, and OTf groups.

10. The application according to claim 8, characterized in that, The bisindolebenzene compounds are selected from the following structural formulas:

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