Synthesis method of a multi-substituted carbazole compound

Abstract

The present invention belongs to the field of organic chemical synthesis, and discloses a new method for synthesizing polysubstituted carbazole compounds. The present invention uses indolocyclopentanone as a raw material, first reacts with triethylamine and triisopropylsilyl trifluoromethanesulfonate to form an enol silyl ether, then reacts with bromoform / chloroform and potassium tert-butoxide to form a carbazole compound intermediate, and finally under the action of tetrabutylammonium fluoride, the silyl group is removed to generate a stable carbazole compound. This synthetic route has the advantages of easily available raw materials, low price, no metal catalyst, wide substrate applicability, etc., and has good application prospects in the fields of organic synthesis and medicine and pharmacy.

Description

Technical Field

[0001] The present invention belongs to the field of organic chemical synthesis, and particularly relates to a new method for synthesizing multi-substituted carbazole compounds. Background Art

[0002] Carbazole and its carbazole alkaloids are important natural products and have extremely wide application prospects in the fields of biomedicine, optoelectronic materials, etc. The discovery of carbazole itself can be traced back to 1872. Subsequently, hundreds of carbazole compounds have been isolated from Rutaceae plants such as Murraya, Clausena, and Glycosmis. Research has found that carbazole compounds have anti-inflammatory, antifungal, anti-tumor, anti-malaria, anti-viral, anti-Alzheimer's disease and other effects [Chemical Reviews, 2012, 112(6), 3193 - 3328; Chemical Reviews, 2002, 102(11), 4303 - 4428.]. In 1965, murrayanine found in the spice Murraya koenigii had antibacterial effects. Subsequently, more carbazole structures were found in this plant, including koenoline [Phytochemistry, 1985, 24(12), 3041 - 3043.], mukoeic acid [Phytochemistry, 1971, 10(8), 1967 - 1970.] and mukonal [Phytochemistry, 1984, 23(2), 471 - 472.], etc. Subsequently, more and more research on carbazole compounds in the biological and medical aspects has been carried out. The carbazole compound carvedilol approved by the US Food and Drug Administration for marketing is an α,β receptor blocker, which has a vasodilating effect while blocking the receptor and is used to treat congestive heart failure and hypertension [Expert opinion on drug discovery, 2006, 1(1), 85 - 89.]. To date, more and more carbazole natural products or modified structures have been found to have antibacterial, anti-malaria, anti-cancer, and anti-Alzheimer's disease properties. Therefore, developing efficient methods for synthesizing carbazole compounds has become one of the current research hotspots.

[0003] The synthetic methods of carbazole compounds can be divided into two categories: one is to construct indole derivatives and further build a benzene ring (A / C ring) to form a carbazole skeleton; the other is to construct biphenyl compounds and further carry out intramolecular cyclization to build a pyrrole ring (B ring) to form a carbazole skeleton. The methods for synthesizing carbazole compounds by constructing the A / C ring include electrocyclization reaction, cycloaddition reaction, Friedel-Crafts alkylation reaction, olefin metathesis reaction, etc. The methods for synthesizing carbazole compounds by constructing the B ring include metal-catalyzed coupling reaction, reaction involving iron-arene complex, Fischer indole synthesis method, etc. In the present invention, indolocyclopentanone is used as a raw material to construct a benzene ring (A / C ring) to obtain a carbazole skeleton, followed by enolization reaction to generate enol silyl ether, and further carbene reaction to generate carbazole compounds. There are no relevant literatures and patent reports on this synthetic method at present. Summary of the Invention

[0004] The object of the present invention is to provide a new synthetic method for polysubstituted carbazole compounds, and the carbazole compounds have the structure shown in general formula (II).

[0005] To achieve the object of the present invention, indolocyclopentanone is used as a raw material in the present invention. First, an enolization reaction occurs, and then a carbene insertion reaction is carried out with potassium tert-butoxide and bromoform / chloroform to generate an intermediate of carbazole compounds, and finally the silyl group is removed to generate a stable carbazole compound.

[0006]

[0007] Wherein,

[0008] R 1 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluorine, chlorine, bromine, iodine, nitro, methoxy, nitrile, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxyl, aldehyde, ester group, etc.;

[0009] R 2 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluorine, chlorine, bromine, iodine, nitro, methoxy, nitrile, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxyl aldehyde, ester group, etc.;

[0010] R 1 +R 2 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0011] R 3= H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0012] R 2 +R 3 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0013] R 4 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0014] R 3 +R 4 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0015] R 5 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0016] R 6 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0017] R 5 +R 6 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0018] R 7 = H, CH3, C2H5, MOM, Boc, Tos, Bn;

[0019] X = Br, Cl.

[0020] The synthesis method of the carbazole compound is characterized by the following steps:

[0021] The indolocyclopentenone compound is added into a reaction flask, protected by nitrogen, and dry dichloromethane, triethylamine, and triisopropylsilyl trifluoromethanesulfonate are added. Stir the reaction at room temperature, monitor by TLC. After the reaction is completed, extract, dry the organic phase, filter, evaporate to dryness, add potassium tert-butoxide, protect by nitrogen, add n-hexane at -78 °C to -80 °C, stir, then add bromoform or chloroform, stir, transfer and continue to stir the reaction at room temperature, monitor by TLC, evaporate to dryness, add tetrabutylammonium fluoride for reaction. After the reaction is completed, extract, dry, filter, evaporate to dryness, and separate by column chromatography to obtain the polysubstituted carbazole compound (II).

[0022] The structural formula of the indolocyclopentenone (I) is as follows:

[0023]

[0024] Among them,

[0025] R 1 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluorine, chlorine, bromine, iodine, nitro, methoxy, nitrile, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxyl, aldehyde, ester group, etc.;

[0026] R 2 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluorine, chlorine, bromine, iodine, nitro, methoxy, nitrile, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxyl aldehyde, ester group, etc.;

[0027] R 1 +R 2 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0028] R 3 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluorine, chlorine, bromine, iodine, nitro, methoxy, nitrile, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxyl, aldehyde, ester group, etc.;

[0029] R 2 +R 3= –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0030] R 4 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0031] R 3 +R 4 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0032] R 5 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0033] R 6 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group, etc.;

[0034] R 5 +R 6 = –(CH2)3–, –OCH2O–, –(CH2)4–, –(CH2)3(CH3)CH–, –(CH2)3(CH3)2C–, –CH(CH3)(CH2)3–, –C(CH3)2(CH2)3–;

[0035] R 7 = H, CH3, C2H5, MOM, Boc, Tos, Bn.

[0036] The reaction general formula of the preparation method described in the present invention is as follows:

[0037]

[0038] The beneficial effects of the present invention are as follows: The present invention provides a new method for synthesizing polysubstituted carbazole compounds with easily available raw materials and good substrate adaptability. The target compounds are directly obtained through enolization and carbene insertion, and the yield reaches more than 50%. Compared with the previous methods, not only the use of transition metal catalysts is abandoned, but also the reagents used are cheap and easily available, and the conditions are relatively mild. This synthetic strategy provides a brand-new method for synthesizing carbazole compounds, with cheap and easily available raw materials and a wide range of applicable reaction substrates. The carbazole compounds synthesized by this method can further react to form natural products. Detailed implementation manners

[0039] The technical solutions 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 a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Example 1

[0041] The preparation method of polysubstituted carbazole compounds is as follows:

[0042] In a 25 mL round-bottom flask, add 2-methyl-3-phenyl-3,4-dihydrocyclopenta[b]indol-1(2H)-one (1.0 mmol), under nitrogen protection, add 5 mL of dichloromethane, triethylamine (4.0 mmol), and triisopropylsilyl trifluoromethanesulfonate (3.0 mmol), stir at room temperature for 1.0 h, monitor by TLC. After the reaction is completed, extract with water three times, dry with anhydrous sodium sulfate, transfer and rotary evaporate. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether, under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min, then add bromoform (4.0 mmol) and react at this temperature for 1.5 h, and then transfer and react at room temperature for 1.5 h, monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness, add 2 mL of a tetrahydrofuran solution containing tetrabutylammonium fluoride (1 mol / L), stir for 15 min, monitor by TLC. After the reaction is completed, add water, extract with ethyl acetate three times, rotary dry and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0043]

[0044] 1 H NMR (400 MHz, CDCl3) δ 8.28 (d, J = 7.8 Hz, 1H), 7.73 (s, 1H), 7.57–

[0045] 7.49 (m, 2H), 7.48–7.42 (m, 1H), 7.39–7.32 (m, 3H), 7.29–7.21 (m, 2H), 6.27 (s, 1H), 2.38 (s, 3H) ppm. 13 13C NMR (101 MHz, CDCl3) δ 147.1, 139.1, 138.8, 137.5, 132.3, 130.3, 129.2, 127.8, 125.3, 122.9, 122.4, 120.0, 118.3, 110.1, 109.4, 103.9, 21.2. Yield 50%.

[0046] Example 2

[0047] A method for preparing a polysubstituted carbazole compound, the steps are as follows:

[0048] In a 25 mL round-bottom flask, add tert-butyl 2-methyl-1-oxo-3-phenyl-2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate (1.0 mmol), under nitrogen protection, add 5 mL of dichloromethane, triethylamine (2.0 mmol), triisopropylsilyl trifluoromethanesulfonate (1.5 mmol), stir at room temperature for 1.0 h, monitor by TLC. After the reaction is completed, extract with water three times, dry over anhydrous sodium sulfate, transfer and rotary evaporate. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether, under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min, then add bromoform (4.0 mmol) and react at this temperature for 1.5 h, then transfer and react at room temperature for 1.5 h, monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness, add 2 mL of a tetrahydrofuran solution containing tetrabutylammonium fluoride (1 mol / L), stir for 15 min, monitor by TLC. After the reaction is completed, add water, extract with ethyl acetate three times, rotary dry and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0049]

[0050] 1 1H NMR (400 MHz, CDCl3) δ 8.26-8.19 (m, 1H), 8.02–7.94 (m, 1H), 7.45-7.35 (m, 2H), 7.33–7.20 (m, 3H), 7.07–6.99 (m, 2H), 4.38 (d, J = 2.0 Hz, 1H), 2.78 (dq, J = 2.0, 7.6 Hz, 1H), 1.53 (d, J = 7.6 Hz, 3H), 1.31 (s, 9H) ppm. 1313C NMR (101 MHz, CDCl3) δ 198.8, 164.7, 148.5, 142.1, 141.6, 128.9, 127.0, 126.4, 125.8, 125.2, 121.9, 121.1, 116.0, 85.5, 58.4, 51.9, 27.6, 16.8. Yield 52%.

[0051] Example 3

[0052] A method for preparing a polysubstituted carbazole compound, the steps are as follows:

[0053] In a 25 mL round-bottom flask, add tert-butyl 2,3-dimethyl-1-oxo-2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate (1.0 mmol), under nitrogen protection, add 5 mL of dichloromethane, triethylamine (2.0 mmol), and triisopropylsilyl trifluoromethanesulfonate (1.5 mmol), stir at room temperature for 1.0 h, monitor by TLC. After the reaction is completed, add water and extract three times, dry over anhydrous sodium sulfate, transfer and rotary evaporate. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether, under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min, then add bromoform (4.0 mmol) and react at this temperature for 1.5 h, then transfer and react at room temperature for 1.5 h, monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness, add 2 mL of a tetrahydrofuran solution containing tetrabutylammonium fluoride (1 mol / L), stir for 15 min, monitor by TLC. After the reaction is completed, add water, extract three times with ethyl acetate, rotary dry and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0054]

[0055] 1 1H NMR (400 MHz, CDCl3) δ 8.28 - 8.19 (m, 1H), 8.00 (d, J = 8.0 Hz, 1H), 7.45–7.38 (m, 1H), 7.38–7.32 (m, 1H), 6.09 (s, 1H), 2.53 (s, 3H), 2.35 (s, 3H), 1.69 (s, 9H) ppm. 13 13C NMR (101 MHz, CDCl3) δ 151.3, 145.5, 140.1, 139.6, 135.0, 126.4, 125.4, 123.5, 123.0, 118.0, 114.7, 113.6, 108.9, 84.1, 28.3, 20.8, 18.8. Yield 55%.

[0056] Example 4

[0057] Preparation method of polysubstituted carbazole compounds, the steps are as follows:

[0058] In a 25 mL round-bottom flask, add tert-butyl 2-methyl-1-oxo-2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate (1.0 mmol), under nitrogen protection, add 5 mL of dichloromethane, triethylamine (2.0 mmol), triisopropylsilyl trifluoromethanesulfonate (1.5 mmol), stir at room temperature for 1.0 h, monitor by TLC. After the reaction is completed, add water for extraction three times, dry with anhydrous sodium sulfate, transfer and rotary evaporate. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether, under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min, then add bromoform (4.0 mmol) and react at this temperature for 1.5 h, then transfer and react at room temperature for 1.5 h, monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness, add 2 mL of a tetrahydrofuran solution containing tetrabutylammonium fluoride (1 mol / L), stir for 15 min, monitor by TLC. After the reaction is completed, add water, extract three times with ethyl acetate, rotary dry and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0059]

[0060] 1 H NMR (400 MHz, CDCl3) δ 8.28–8.24 (m, 1H), 8.21 (d, J = 8.3 Hz, 1H), 7.90 (s, 1H), 7.47–7.40 (m, 1H), 7.40–7.33 (m, 1H), 6.21 (s, 1H), 2.56 (s, 3H), 1.76 (s, 9H) ppm. 13 C NMR (101 MHz, CDCl3) δ 151.2, 147.4, 139.0, 137.9, 136.4, 126.5, 124.6, 123.5, 122.8, 115.8, 112.2, 110.4, 106.9, 84.4, 28.5, 24.4. The yield is 62%.

[0061] Example 5

[0062] Preparation method of polysubstituted carbazole compounds, the steps are as follows:

[0063] In a 25 mL round-bottom flask, add tert-butyl 3-ethyl-2-methyl-1-oxo-2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate (1.0 mmol). Under nitrogen protection, add 5 mL of dichloromethane, triethylamine (2.0 mmol), and triisopropylsilyl trifluoromethanesulfonate (1.5 mmol). Stir at room temperature for 1.0 h. Monitor by TLC. After the reaction is completed, extract with water three times, dry over anhydrous sodium sulfate, and transfer to a rotary evaporator. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether. Under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min. Then add bromoform (4.0 mmol) and react at this temperature for 1.5 h. Then transfer and react at room temperature for 1.5 h. Monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness. Add 2 mL of a tetrahydrofuran solution containing tetrabutylammonium fluoride (1 mol / L) and stir for 15 min. Monitor by TLC. After the reaction is completed, add water, extract with ethyl acetate three times, dry by evaporation and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0064]

[0065] 1 H NMR (400 MHz, CDCl3) δ 8.30–8.21 (m, 1H), 7.99–7.90 (m, 1H), 7.45–7.39 (m, 1H), 7.38–7.32 (m, 1H), 6.13 (s, 1H), 2.98 (q, J = 7.5 Hz, 2H), 2.58 (s, 3H), 1.71 (s, 9H), 1.17 (t, J = 7.5 Hz, 3H) ppm. 13 C NMR (101 MHz, CDCl3) δ 151.8, 145.6, 140.1, 138.9, 134.6, 126.3, 125.3, 124.4, 123.3, 123.0, 114.3, 114.0, 109.6, 84.2, 28.3, 24.0, 20.7, 13.6. The yield is 58%.

[0066] Example 6

[0067] A method for preparing a polysubstituted carbazole compound, the steps are as follows:

[0068] In a 25 mL round-bottom flask, add tert-butyl 3-ethyl-2-methyl-1-oxo-2,3-dihydrocyclopenta[b]indole-4(1H)-carboxylate (1.0 mmol). Under nitrogen protection, add 5 mL of dichloromethane, triethylamine (2.0 mmol), and triisopropylsilyl trifluoromethanesulfonate (1.5 mmol). Stir at room temperature for 1.0 h and monitor by TLC. After the reaction is completed, extract with water three times, dry over anhydrous sodium sulfate, and transfer for rotary evaporation. Add potassium tert-butoxide (7.0 mmol) to the obtained enol silyl ether. Under nitrogen protection, add 5 mL of n-hexane and stir at -78 °C for 5 min. Then add chloroform (4.0 mmol) and react at this temperature for 1.5 h. After that, transfer and react at room temperature for 1.5 h and monitor by TLC. After the reaction is completed, directly evaporate the solvent to dryness, add a tetrahydrofuran solution (1 mol / L) containing 2 mL of tetrabutylammonium fluoride, stir for 15 min, and monitor by TLC. After the reaction is completed, add water, extract with ethyl acetate three times, rotary dry and load the sample, and purify by silica gel column chromatography to obtain the final product.

[0069]

[0070] 1 H NMR (400 MHz, CDCl3) δ 8.29–8.24 (m, 1H), 8.21 (d, J = 8.3 Hz, 1H), 7.88 (s, 1H), 7.46–7.40 (m, 1H), 7.39–7.34 (m, 1H), 6.17 (s, 1H), 2.53 (s, 3H), 1.76 (s, 9H) ppm. 13 C NMR (101 MHz, CDCl3) δ 151.2, 146.5, 138.2, 138.0, 134.8, 126.4, 124.6, 123.5, 122.7, 115.9, 114.4, 112.4, 110.2, 84.3, 28.5, 21.5. The yield is 67%.

[0071] The above are only representative embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a multi-substituted carbazole compound, characterized in that: It is achieved through the following steps: Add the indolocyclopentanone compound (I) into a reaction flask, protect it with nitrogen, add dry dichloromethane, triethylamine, triisopropylsilyl trifluoromethanesulfonate, stir the reaction at room temperature, monitor by TLC. After the reaction is completed, carry out extraction, dry the organic phase, filter and transfer to rotary evaporation. After evaporation to dryness, add potassium tert-butoxide, protect with nitrogen, add n-hexane at -78 °C to -80 °C, stir, then add bromoform or chloroform, stir, transfer and continue to stir the reaction at room temperature, monitor by TLC. After evaporation to dryness, add tetrabutylammonium fluoride for reaction. After the reaction is completed, carry out extraction, drying, filtration, evaporation to dryness, and separate by column chromatography to obtain the polysubstituted carbazole compound (II); Among them, R 1 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester; R 2 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, ester group; R 3 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester group; R 4 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester; R 5 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester; R 6 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, fluoro, chloro, bromo, iodo, nitro, methoxy, cyano, amino, –N(CH3)2, –CH2N(CH3)2, phenyl, benzyl, hydroxy, aldehyde, ester; R 7 = H, CH3, C2H5, MOM, Boc, Tos, Bn; X = Br, Cl.

2. The method for preparing the polysubstituted carbazole compound according to claim 1, characterized in that: R 1 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl; R 2 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl; R 3 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl; R 4 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl; R 5 = methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl; R 6 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, phenyl; R 7 = H, Boc; X = Br, Cl.

3. The method for preparing the polysubstituted carbazole compound according to claim 2, characterized in that: R 1 = H; R 2 = H; R 3 = H; R 4 = H; R 5 = methyl, ethyl; R 6 = H, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, phenyl; R 7 = H, Boc; X = Br, Cl.

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