Nitrogen-containing heterocyclic compound as well as preparation method and application thereof

Abstract

The invention relates to a nitrogen-containing heterocyclic compound as well as a preparation method and application thereof, belongs to the technical field of heterocyclic compound synthesis, and solves the problems of low reaction efficiency and high energy consumption caused by the fact that an existing method for synthesizing an indole maleimide derivative needs to be carried out step by step. The preparation method comprises the following steps: step 1, adding indoleacetamide and a nucleophilic reagent into a mixed solution, and reacting; 2, performing post-treatment to obtain a nitrogen-containing heterocyclic compound; the mixed solution comprises alkali, an additive and an organic solvent; the alkali comprises one of triethylamine (Et3N), N, N-diisopropylethylamine, pyridine and 1, 8-diazabicyclo [5.4. 0] undec-7-ene, and the alkali comprises one of 1, 8-diazabicyclo [5.4. 0] undec-7-ene.

Description

Technical Field

[0001] The present invention relates to the technical field of heterocyclic compound synthesis, and relates to nitrogen-containing heterocyclic compounds, their preparation methods and applications, and particularly relates to an indole maleimide derivative and its preparation method. Background Art

[0002] Nitrogen-containing heterocyclic compounds have extensive applications in the fields of organic synthesis, medicine, pesticides, and materials science. Therefore, developing novel and practical methods for constructing various nitrogen-containing heterocyclic skeletons has become the research goal of many organic synthetic chemists.

[0003] Maleimide and indole, as advantageous structural skeletons, have extensive applications in the fields of drug R & D, agrochemical research, and advanced material design.

[0004] Existing methods for synthesizing indole maleimide derivatives are carried out step by step, resulting in low reaction efficiency and high energy consumption. In addition, existing processes require the use of transition metal catalysts, which have disadvantages such as high cost and metal residues in the products. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a nitrogen-containing heterocyclic compound, its preparation method and application, and can at least solve one of the following technical problems: (1) Existing methods for synthesizing indole maleimide derivatives need to be carried out step by step, resulting in low reaction efficiency and high energy consumption; (2) Existing processes require the use of transition metal catalysts, which are costly and have metal residues in the products.

[0006] The object of the present invention is mainly achieved through the following technical solutions: In the first aspect, the present invention provides a preparation method of a nitrogen-containing heterocyclic compound, including the following steps: Step 1: Add indole acetamide and a nucleophile to a mixed solution and react; Step 2: Perform post-treatment to obtain a nitrogen-containing heterocyclic compound; The mixed solution includes a base, an additive, and an organic solvent; The base includes one of triethylamine (Et3N), N,N-diisopropylethylamine, pyridine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0007] Optionally, the indole acetamide has a structure shown in Structural Formula 1a: ; In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine.

[0008] Optionally, the nucleophile is a phosphorus ylide reagent, including one of an α-ester-based phosphorus ylide reagent and an α-acetophenyphosphorus ylide reagent.

[0009] Optionally, the α-ester-based phosphorus ylide reagent has a structure shown in Structural Formula 2a: ; In the formula, R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl.

[0010] Optionally, the α-acetophenyphosphorus ylide reagent has a structure shown in Structural Formula 2b: ; In the formula, R is selected from an electron-donating functional group or an electron-withdrawing functional group.

[0011] Optionally, the electron-donating functional group is selected from any one of hydrogen, methoxy, and methyl; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro, and cyano.

[0012] Optionally, the additive includes one of dipotassium hydrogen phosphate (K2HPO4), potassium dihydrogen phosphate (KH2PO4), glacial acetic acid, 4-dimethylaminopyridine (DMAP), sodium carbonate, and zinc chloride (ZnCl2).

[0013] Optionally, the nucleophile further includes an α-cyclic lactone phosphorus ylide reagent.

[0014] In a second aspect, the present invention provides a nitrogen-containing heterocyclic compound prepared by the above method.

[0015] In a third aspect, the present invention provides the application of the above preparation method and the above nitrogen-containing heterocyclic compound in the preparation of anti-cancer drugs.

[0016] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects: (1) By jointly adjusting the reaction raw materials and the reaction system, the present invention compresses the traditional multi-step reaction into a one-pot single-step method, improves the reaction efficiency, and has low energy consumption.

[0017] (2) By optimizing the reaction system to include a mixed solution of a base, an additive, and an organic solvent, and by optimizing the types of the base, the additive, and the organic solvent, the reaction can proceed without adding an expensive transition metal catalyst, reducing the production cost and leaving no metal residue in the product.

[0018] (3) The reaction conditions of the present invention are mild, and the reaction can be carried out under normal pressure and in an air environment, without requiring a deoxygenated and low-temperature reaction environment, reducing the production cost.

[0019] (4) The same system of the present invention is compatible with electron-withdrawing groups (fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro, cyano, and naphthyl), electron-donating groups (hydrogen, methoxy, methyl), and α-position bulky groups (such as naphthalene ring), achieving the compatibility of dynamic functional groups in the same system, solving the problem of insufficient functional group compatibility in the existing methods, and realizing broad-spectrum substrate applicability.

[0020] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings are only for the purpose of showing specific embodiments and are not considered as a limitation to the present invention. Throughout the drawings, the same reference signs represent the same components.

[0022] The methods in the present invention are all conventional methods unless otherwise specified. The raw materials can be obtained from commercial public channels unless otherwise specified; Figure 1 1H NMR spectrum of product 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3a) in the example; Figure 2 13C NMR spectrum of product 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3a) in the example; Figure 3 1H NMR spectrum of product 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (4a) in the example; Figure 4 13C NMR spectrum of product 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (4a) in the example; Figure 5 1H NMR spectrum of product 3b; Figure 6 13C NMR spectrum of product 3b; Figure 7 1H NMR spectrum of product 3c; Figure 8 13C NMR spectrum of product 3c; Figure 9 1H NMR spectrum of product 3d; Figure 10 13C NMR spectrum of product 3d; Figure 11 1H NMR spectrum of product 3e; Figure 12 13C NMR spectrum of product 3e; Figure 13 1H NMR spectrum of product 3f; Figure 14 Carbon spectrum of product 3f; Figure 15 Fluorine nuclear magnetic resonance spectrum of product 3f; Figure 16 Proton nuclear magnetic resonance spectrum of product 3g; Figure 17 Carbon spectrum of product 3g; Figure 18 Proton nuclear magnetic resonance spectrum of product 3h; Figure 19 Carbon spectrum of product 3h; Figure 20 Proton nuclear magnetic resonance spectrum of product 4b; Figure 21 Carbon spectrum of product 4b; Figure 22 Fluorine nuclear magnetic resonance spectrum of product 4b; Figure 23 Proton nuclear magnetic resonance spectrum of product 4c; Figure 24 Carbon spectrum of product 4c; Figure 25 Proton nuclear magnetic resonance spectrum of product 4d; Figure 26 Carbon spectrum of product 4d; Figure 27 Proton nuclear magnetic resonance spectrum of product 4e; Figure 28 Carbon spectrum of product 4e; Figure 29 Proton nuclear magnetic resonance spectrum of product 4f; Figure 30 Carbon spectrum of product 4f; Figure 31 Proton nuclear magnetic resonance spectrum of product 4g; Figure 32 Carbon spectrum of product 4g; Figure 33 Fluorine nuclear magnetic resonance spectrum of product 4g; Figure 34 Proton nuclear magnetic resonance spectrum of product 4h; Figure 35 Carbon spectrum of product 4h; Figure 36 Proton nuclear magnetic resonance spectrum of product 4i; Figure 37 Carbon spectrum of product 4i; Figure 38 Proton nuclear magnetic resonance spectrum of product 4j; Figure 39 Carbon spectrum of product 4j; Figure 40 Proton nuclear magnetic resonance spectrum of product 4k; Figure 41 Carbon spectrum of product 4k; Figure 42 Proton nuclear magnetic resonance spectrum of product 4l; Figure 43 13C NMR spectrum of product 4l Detailed implementation manners

[0023] The preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. The accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0024] In a first aspect, the present invention provides a method for preparing a nitrogen-containing heterocyclic compound. Specifically, it is a method for preparing an indole maleimide derivative, which includes the following steps: Step 1: Add indoleacetamide and a nucleophile to a mixed solution and react; Step 2: Perform post-treatment to obtain an indole maleimide derivative.

[0025] Specifically, indoleacetamide has the structure shown in Structural Formula 1a: ; In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine.

[0026] The nucleophile is a phosphonium ylide reagent, including one of an α-ester phosphonium ylide reagent and an α-acetylphenyl phosphonium ylide reagent.

[0027] When the nucleophile is an α-ester phosphonium ylide reagent, it has the structure shown in Structural Formula 2a: ; In the formula, R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl.

[0028] The reaction equation of indoleacetamide and the α-ester phosphonium ylide reagent is as follows: ; The obtained indole maleimide derivative has the structure shown in Structural Formula 3: ; In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine; R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl. The specific structural formula is as follows: ; It should be noted that the percentage after the product number is the separation yield.

[0029] When the nucleophile is an α-acetylphenyl phosphonium ylide reagent, it has the structure shown in Structural Formula 2b: ; In the formula, R is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from any one of hydrogen, methoxy group, and methyl group; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl group, trifluoromethyl group, nitro group, and cyano group.

[0030] The reaction equation of indoleacetamide and α-acetophenyldiylphosphonium ylide reagent is as follows: ; The obtained indole maleimide derivative has the structure shown in Structural Formula 4: ; In the formula, R is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from any one of hydrogen, methyl group, or methoxy group; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl group, trifluoromethyl group, nitro group, and cyano group. The specific structural formula is as follows: .

[0031] It should be noted that the percentage after the product number is the separation yield.

[0032] Specifically, in Step 1, the reaction temperature is 70 - 120 °C, for example, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 100 °C, 110 °C, 120 °C. The reaction time is 3 - 14 h, for example, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h.

[0033] The mixed solution includes a base, an additive, and an organic solvent.

[0034] Among them, the base includes one of triethylamine (Et3N), N,N-diisopropylethylamine (DIPEA), pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and preferably triethylamine.

[0035] The additive includes one of dipotassium hydrogen phosphate (K2HPO4), potassium dihydrogen phosphate (KH2PO4), glacial acetic acid, 4-dimethylaminopyridine (DMAP), sodium carbonate, and zinc chloride (ZnCl2).

[0036] The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, and chloroform.

[0037] More specifically, when the nucleophile is an α-esteryl phosphonium ylide reagent, the reaction temperature is 70 - 120 °C, for example, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 100 °C, 110 °C, 120 °C. The reaction time is 3 - 5 h, for example, 3 h, 3.5 h, 4 h, 4.5 h, 5 h.

[0038] The molar ratio of indole acetamide to the α-esteryl phosphonium ylide reagent is (0.5 - 2):1, for example, 1:2, 1:1, 2:1.

[0039] The mixed solution includes triethylamine, potassium dihydrogen phosphate and an organic solvent. The molar ratio of indole acetamide to triethylamine is 1:(2 - 4), for example, 1:2, 1:3, 1:4. The molar ratio of indole acetamide to potassium dihydrogen phosphate is 1:(4 - 6), for example, 1:4, 1:5, 1:6. The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, chloroform. The molar volume ratio of indole acetamide to the organic solvent is (0.1 - 0.2):1, where the unit of mole is mmol and the unit of volume is mL.

[0040] When the nucleophile is an α-acetylphenyl phosphonium ylide reagent, the reaction temperature is 70 - 90 °C, for example, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C. The reaction time is 8 - 15 h, for example, 8 h, 9 h, 10 h, 12 h, 14 h, 15 h.

[0041] The molar ratio of indole acetamide to the α-acetylphenyl phosphonium ylide reagent is (3 - 1):2, for example, 3:2, 1:1, 1:2.

[0042] The mixed solution includes triethylamine, zinc chloride and an organic solvent.

[0043] Among them, the molar ratio of the α-acetylphenyl phosphonium ylide reagent to triethylamine is 1:(2 - 4), for example, 1:2, 1:3, 1:4. The molar ratio of the α-acetylphenyl phosphonium ylide reagent to zinc chloride is 1:(1 - 3), for example, 1:1, 1:2, 1:3. The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, chloroform. Preferably it is tetrahydrofuran (THF). The molar volume ratio of the α-acetylphenyl phosphonium ylide reagent to the organic solvent is (0.1 - 0.2):1, where the unit of mole is mmol and the unit of volume is mL.

[0044] In Step 2, the post-treatment includes concentration and purification. Specifically, the reaction mixture from Step 1 is concentrated under vacuum to obtain a residue, and the residue is purified by flash column chromatography on silica gel, eluted to obtain the product indolylmaleimide derivative. The eluent is a mixture of petroleum ether and ethyl acetate, and the volume ratio of the two is petroleum ether:ethyl acetate = 10:1 to 2:1, for example, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1.

[0045] The possible reaction mechanism in the present invention is as follows: ; First, substrate 1a undergoes a concerted deprotonation and elimination reaction under the action of triethylamine to obtain an α-lactam intermediate Int-1, which can isomerize to Int-2. Subsequently, the phosphorane reagent 2 reacts with Int-2 to generate an zwitterionic intermediate Int-3, and its nitrogen anion attacks the carbonyl group to undergo a 5-exo cyclization reaction to form Int-4. When R3 is a benzene ring, Int-4 undergoes a proton transfer and eliminates triphenylphosphine to obtain the hydroxylated product 4; when R3 is an ethoxy group, the hydroxylated product is further deprotonated, thereby eliminating a molecule of ethoxy anion to obtain the maleimide derivative 3.

[0046] In summary, the present invention utilizes indoleacetamide and a phosphorane reagent containing an α-carbonyl group to achieve a cascade alkenylation / cyclization reaction under the action of triethylamine. Among them, a nucleophilic phosphine reagent containing an α-ester group can obtain an indolylmaleimide derivative: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (Product 3); a phosphorane reagent containing an α-acetylphenyl group separates to obtain a hydroxylated unsaturated alcohol: 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (Product 4). This reaction is simple to operate, does not require the addition of expensive transition metals, and has a wide substrate applicability. The present invention will contribute to expanding the application of nucleophilic phosphine reagents in the synthesis of nitrogen heterocycles and provide an effective new method for the synthesis of heterocyclic compounds.

[0047] In a second aspect, the present invention provides an indolylmaleimide derivative prepared by the above preparation method, which has the structure shown in Structural Formula 4: ; In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine; R is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from any one of hydrogen, methyl, and methoxy; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro, and cyano. The specific structural formula is as follows: .

[0048] It should be noted that the percentage after the product number is the separation yield.

[0049] Alternatively, the indolylmaleimide derivative has the structure shown in Structural Formula 3: ; In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine; R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl. The specific structural formula is as follows: .

[0050] It should be noted that the percentage after the product number is the separation yield.

[0051] In the present invention, the indolylmaleimide derivative having Structural Formula 4 has an inhibitory effect on the proliferation of two kinds of tumor cells, human leukemia cells (K562) and prostate cancer cells (PC-3). Specifically, the IC50 for human leukemia cells (K562) is 21.6 - 33.0 μmol·L -1 , and the IC50 for prostate cancer cells (PC-3) is 15.1 - 29.1 μmol·L -1 .

[0052] Among them, the inhibitory activities of products 4b and 4g against K562 are comparable to those of cisplatin, and the inhibitory activities of the remaining products are slightly weaker than that of cisplatin.

[0053] The inhibitory activities of products 4b, 4c, 4d, 4e, and 4g against PC-3 are superior to that of cisplatin, and the inhibitory activities of the remaining products are comparable to that of cisplatin. The inhibitory activity of product 4g against PC-3 is the strongest (IC50 = 15.1 μmol·L -1 ), which is 1.71 times that of cisplatin.

[0054] In the present invention, the indolylmaleimide derivative having Structural Formula 3 has an inhibitory effect on the proliferation of two kinds of tumor cells, human leukemia cells (K562) and prostate cancer cells (PC-3). Specifically, the IC50 for human leukemia cells (K562) is 11.2 - 26.1 μmol·L -1 , and the IC50 for prostate cancer cells (PC-3) is 16.1 - 26.2 μmol·L -1 .

[0055] Among them, the inhibitory activities of products 3b, 3c, 3d, 3f, 3g, and 3h against K562 are significantly superior to that of cisplatin, and the inhibitory activities of the remaining products are comparable to that of cisplatin. The inhibitory activity of product 3f against K562 is the strongest (IC50 = 11.2 μmol·L-1), which is 2.11 times that of cisplatin.

[0056] Products 3a, 3g, 3h, and 3f showed superior inhibitory activity against PC-3 compared to cisplatin, while the inhibitory activity of the remaining products was comparable to that of cisplatin. Product 3g showed the strongest inhibitory activity against PC-3 (IC50 = 16.1 µmol·L-1), which was 1.60 times that of cisplatin.

[0057] In summary, product 3 synthesized by the present invention: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione and product 4: 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrole-2-one are both compounds with anticancer activity.

[0058] The indolemaleimide derivatives of the present invention enrich the types of existing anticancer drugs and have obvious inhibitory effects on the proliferation of human leukemia cells (K562) and prostate cancer cells (PC-3).

[0059] Example 1 The present invention adds indoleacetamide of structural formula 1 and α-ester phosphorus ylide reagent of structural formula 2a into a mixture containing triethylamine and After the reaction was completed, the reaction mixture was concentrated under vacuum. A small amount of product 3a was successfully monitored (Table 1, No. 1). When , the yield of the product is significantly reduced (No. 3). and When , the yield of product 3 was 37% and 42% (serial numbers 2 and 4). Through the screening of organic solvents, it was found that chloroform was the best solvent for product yield, with an isolated yield of 63% (serial number 7). When the reaction temperature was 0.5 °C, the NMR yield of product 3a was only 44% (No. 8). Furthermore, the addition of acidic additives such as HCl and glacial acetic acid to the system (Nos. 9-10) resulted in poor reaction performance. Adjusting the reactant ratio to 2:1 or 1:1 resulted in a slight decrease in yield (Nos. 11-12). Even at 40°C and with extended reaction times, the reaction still did not proceed efficiently (No. 13).

[0060] Table 1 Optimization of reaction conditions a ; a Unless otherwise stated, all reactions were carried out at 80 °C for 4 h. The reaction system contained 1a (0.1 mmol), 2a (0.2 mmol), Et3N (0.3 mmol), additive (0.5 mmol), and solvent (1.0 mL). b 1The yield of 1H NMR was determined using 4-methylbenzophenone as the internal standard; c 1a:2a = 2:1; d 1a:2a = 1:1; e React at 40 °C for 24 hours; f Isolation yield.

[0061] It should be noted that in the reaction of No. 7 in Table 1, when determining the isolation yield, the volume ratio of the eluent petroleum ether:ethyl acetate is 10:1.

[0062] In addition, unless otherwise specified, the processes of the present invention are all existing processes. For example, vacuum concentration, flash silica gel column chromatography, elution, etc. all adopt existing processes.

[0063] The reaction equation of this example is as follows: .

[0064] Example 2 This example is basically the same as the example of No. 7 in Table 1, except that the reaction temperature is 70 °C, the reaction time is 5 hours, and the 1 1H NMR yield of product 3a is 57%.

[0065] Example 3 This example is basically the same as the example of No. 7 in Table 1, except that the reaction temperature is 120 °C, the reaction time is 3 hours, and the 1 1H NMR yield of product 3a is 55%.

[0066] Example 4 This example is basically the same as the example of No. 7 in Table 1, except that the base used is N,N-diisopropylethylamine (DIPEA), and the 1 1H NMR yield of product 3a is 43%.

[0067] Comparative Example 1 This comparative example is basically the same as the example of No. 7 in Table 1, except that the reaction temperature is 65 °C, the reaction time is 5 hours, and the 1 1H NMR yield of product 3a is 26%.

[0068] Example 5 In this example, the molar ratio of 1a to 2a is 1:2, the amount of 1a is 0.2 mmol, the amount of 2a is 0.4 mmol (2 equivalents), the organic solvent used is chloroform, the amount is 1.0 mL, the amount of KH2PO4 is 1 mmol (5 equivalents), the amount of Et3N is 0.6 mmol (3 equivalents), the reaction temperature is 80 °C, the reaction time is 4 hours. After the reaction is completed, the reaction mixture is concentrated under vacuum. The yield is the isolated yield. When measuring the isolated yield, the volume ratio of petroleum ether to ethyl acetate as the eluent is 10:1.

[0069] In addition, unless otherwise specified, the processes of the present invention are all existing processes. For example, vacuum concentration, flash column chromatography on silica gel, elution, etc. all adopt existing processes.

[0070] The reaction equation of this example is as follows: ; In this example, the substrate scope of the α-esteryl phosphonium ylide reagent was expanded (Table 2). Some long-chain α-esteryl phosphonium ylide reagents can obtain indole maleimide derivatives in good yields, and the products are 3: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3b - 3d). It should be noted that when using the α-cyclic lactone phosphonium ylide reagent as the nucleophile, the C-O bond is cleaved, and the ring-opening product (3e) is obtained in a yield of 43%. The structural formula of the α-cyclic lactone phosphonium ylide reagent is 2c as follows: .

[0071] Table 2 Reactions of different indole acetamides with different α-esteryl phosphonium ylide reagents ; Note: The phosphonium ylide reagent for synthesizing product 3e is not the α-esteryl phosphonium ylide reagent, but the α-cyclic lactone phosphonium ylide reagent with the structural formula 2c. The yields in the table refer to the isolated yields.

[0072] Example 6 In this example, an indoleacetamide of structural formula 1 (i.e., the structure in structural formula 1a where R1 is hydrogen) and an α-acetylphenylphosphonium ylide reagent of structural formula 2b were used. The molar ratio of 1 to 2b was 3:2 (in serial numbers 1-5 and 10-12) or 1:2 (in serial numbers 6-9). For serial numbers 1-5 and 10-12, 1 was used in an amount of 0.3 mmol (1.5 equivalents) and 2b was used in an amount of 0.2 mmol (1 equivalent). For serial numbers 6-9, 1 was used in an amount of 0.1 mmol (1.5 equivalents) and 2b was used in an amount of 0.2 mmol (1 equivalent). The organic solvent used was tetrahydrofuran (2.0 mL), the additive was ZnCl₂ (0.4 mmol (2 equivalents), and the additive was Et₃N (0.6 mmol (3 equivalents)). The reaction temperature was 80°C, and the reaction time was 10 hours (reaction time for No. 5 in Table 3 was 14 hours). After completion of the reaction, the reaction mixture was concentrated under vacuum. The yield is the isolated yield. The isolated yield was determined using a 10:1 volume ratio of petroleum ether to ethyl acetate as the eluent.

[0073] In addition, unless otherwise specified, the processes of the present invention are all existing processes. For example, vacuum concentration, silica gel column flash chromatography, elution, etc. all adopt existing processes.

[0074] The reaction equation of the present embodiment is as follows: .

[0075] Table 3 Reaction of different α-acetylphenylphosphine ylide reagents ; Note: The phosphonium ylide reagent used to synthesize product 4j is obtained by replacing the phenyl group in structure 2b with a naphthyl group. The yields in the table refer to isolated yields.

[0076] Experimental results indicate that when the phenyl group in general formula 2b is replaced with a naphthyl group (i.e., a naphthalene-containing phosphorus ylide reagent), the preparation method of the present invention also reacts smoothly to yield the corresponding indolemaleimide derivative, structurally shown in 4j (yield: 68%). Therefore, various halogens (fluorine (4b), chlorine (4c), bromine (4d), and iodine (4e)) as well as various electron-withdrawing groups (phenyl (4f), trifluoromethyl (4g), nitro (4h), cyano (4i), and naphthyl (4j)) are well compatible in the reaction system and successfully generate the corresponding cycloaddition products. The introduction of electron-donating groups (methoxy and methyl) at the para position of the benzene ring exhibits superior reactivity compared to the introduction of electron-withdrawing groups (4k-4l).

[0077] Depend on Figures 1 - 2 It can be confirmed that the expected product 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3a) is obtained by the preparation method of the present invention.

[0078] Depend on Figures 3 - 4 It can be confirmed that the expected product 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (4a) is obtained by the preparation method of the present invention.

[0079] Specifically, 4a was obtained as a white solid (42 mg, 66% yield), Rf = 0.44 (PE:EA = 2:1).

[0080] Figure 3 middle, 1 H NMR (500 MHz, CDCl3) δ 8.15 (s, 1H), 7.62 (d, J = 7.9 Hz,1H), 7.47 – 7.45 (m, 2H), 7.38 – 7.35 (m, 2H), 7.34 – 7.32 (m, 1H), 7.19–7.14 (m, 2H), 7.12– 7.09(m, 1H), 7.00 (s, 1H), 3.77 (s, 1H), 3.57 (s, 3H), 2.78 (s, 3H).

[0081] Figure 4 middle, 13 C NMR (126 MHz, CDCl3) δ 170.9, 137.6, 136.9, 135.2, 131.5,129.5, 128.8, 128.5, 126.4, 126.1, 122.2, 120.4, 119.9, 109.8, 105.3, 91.0, 32.9, 24.2.

[0082] in addition, Figures 5 - 43 The hydrogen spectrum, carbon spectrum and nuclear magnetic resonance fluorine spectrum of other products synthesized by the present invention can confirm that the expected products are obtained through the spectra.

[0083] Application Example 1 This application example tests the in vitro anticancer activity of some of the products synthesized in the examples.

[0084] The in vitro anticancer activities of products 3 and 4 synthesized in the present invention against human leukemia cells (K562) and prostate cancer cells (PC-3) were evaluated by MTT method (tetrazolium reduction method) using cisplatin as a positive control. The inhibitory activity of tumor cell growth was expressed as IC50 (half inhibitory concentration). The specific experimental results are shown in Tables 4 and 5, respectively.

[0085] MTT method: dissolve the target product in a small amount of DMSO to prepare 10mmol·L-1 stock solution, dilute the stock solution to the required concentration with RPMI 1640 medium (GIBICO, Invitrogen) containing 10% fetal bovine serum, which are respectively: 50 µmol·L -1 、10 µmol·L -1 、1 µmol·L -1 、0.1µmol·L -1 、10 nmol·L -1 、0.1 nmol·L -1 , and keep the final DMSO concentration less than 0.1%. Culture human leukemia cells (K562) and prostate cancer cells (PC-3) with RPMI 1640 medium containing 10% fetal bovine serum in an incubator with 5% CO2 volume fraction at 37 °C. Detect cell proliferation and growth inhibition by the MTT method. Adjust the number of experimental cells to obtain an absorbance of 1.3 - 2.2 at 570 nm. Treat the cells with the test solutions of the target product at the above 6 concentrations for 72 h respectively, with at least 3 parallels and 3 repeated experiments for each concentration. Use GraphPad Prism 5.0 software for statistical analysis to determine the IC50 value.

[0086] Table 4 Anticancer activity of product 3 synthesized in the present invention ; Note: IC50 (half-inhibitory concentration) refers to the drug concentration required to inhibit 50% of cell growth. The lower the IC50 value, the stronger the drug activity.

[0087] As can be seen from Table 4, the IC50 of product 3 of the present invention for human leukemia cells (K562) is 11.2 - 26.1 µmol·L -1 , and the IC50 for prostate cancer cells (PC-3) is 16.1 - 26.2 µmol·L -1 , indicating that product 3 of the present invention has an inhibitory effect on the proliferation of both types of tumor cells. Among them, the inhibitory activities of products 3b, 3c, 3d, 3f, 3g, 3h on K562 are significantly better than those of cisplatin, and the inhibitory activities of the remaining products are equivalent to those of cisplatin. Product 3f has the strongest inhibitory activity on K562 (IC50 = 11.2 µmol·L-1), which is 2.11 times that of cisplatin.

[0088] It can also be seen from Table 4 that the inhibitory activities of products 3a, 3g, 3h, 3f on PC-3 are better than those of cisplatin, and the inhibitory activities of the remaining products are equivalent to those of cisplatin. Product 3g has the strongest inhibitory activity on PC-3 (IC50 = 16.1 µmol·L-1), which is 1.60 times that of cisplatin.

[0089] Table 5 Anticancer activity of product 4 synthesized in the present invention ; Note: IC50 (half inhibitory concentration) refers to the drug concentration required to inhibit 50% of cell growth. The lower the IC50 value, the stronger the drug activity.

[0090] As can be seen from Table 5, the IC50 of product 4 of the present invention against human leukemia cells (K562) is 21.6-33.0 μmol·L -1 The IC50 for prostate cancer cells (PC-3) is 15.1-29.1µmol·L -1 The results showed that product 4 of the present invention has an inhibitory effect on the proliferation of both tumor cells. The inhibitory activities of products 4b and 4g against K562 are comparable to those of cisplatin, while the inhibitory activities of the remaining products are slightly weaker than those of cisplatin.

[0091] Table 5 also shows that products 4b, 4c, 4d, 4e, and 4g have better inhibitory activity against PC-3 than cisplatin, while the inhibitory activity of the remaining products is comparable to that of cisplatin. Product 4g has the strongest inhibitory activity against PC-3 (IC50 = 15.1 μmol·L -1 ), which is 1.71 times that of cisplatin.

[0092] In summary, product 3 synthesized by the present invention: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione and product 4: 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrole-2-one are both compounds with anticancer activity.

[0093] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a nitrogen-containing heterocyclic compound, characterized in that, It includes the following steps: Step 1: Add indole acetamide and a nucleophile to a mixed solution and react; Step 2: Perform post-treatment to obtain a nitrogen-containing heterocyclic compound; The mixed solution includes a base, an additive, and an organic solvent; The base includes one of triethylamine (Et3N), N,N-diisopropylethylamine, pyridine, 1,8-diazabicyclo[5.4.0]undec-7-ene; The indole acetamide has a structure as shown in Structural Formula 1a: ； In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group. The electron-donating functional group is selected from hydrogen; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, and bromine; The nucleophile is a phosphonium ylide reagent, including one of an α-ester phosphonium ylide reagent and an α-acetylphenyl phosphonium ylide reagent; The nitrogen-containing heterocyclic compound has a structure as shown in Structural Formula 4: ； In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group; R is selected from an electron-donating functional group or an electron-withdrawing functional group; And / or, it has a structure as shown in Structural Formula 3: ； In the formula, R1 is selected from an electron-donating functional group or an electron-withdrawing functional group; R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl.

2. The method according to claim 1, wherein The α-ester phosphonium ylide reagent has a structure as shown in Structural Formula 2a: ； In the formula, R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl.

3. The method according to claim 1, characterized in that, The α-acetylphenyl phosphonium ylide reagent has a structure as shown in Structural Formula 2b: ； In the formula, R is selected from an electron-donating functional group or an electron-withdrawing functional group.

4. The method according to claim 3, characterized in that The electron-donating functional group is selected from any one of hydrogen, methoxy, and methyl; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro, and cyano.

5. The method according to any one of claims 1-4, characterized in that The additive includes one of dipotassium hydrogen phosphate (K2HPO4), potassium dihydrogen phosphate (KH2PO4), glacial acetic acid, 4-dimethylaminopyridine (DMAP), sodium carbonate, and zinc chloride (ZnCl2).

6. The method according to claim 1, wherein The nucleophile also includes an α-cyclic lactone phosphonium ylide reagent.

7. A nitrogen-containing heterocyclic compound, characterized in that, It is prepared by using the method according to any one of claims 1-5.

8. Use of the method according to any one of claims 1-6 and the nitrogen-containing heterocyclic compound according to claim 7 in the preparation of an anti-cancer drug.

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