Nitrogen-containing heterocyclic compound and its preparation method and application

Abstract

The present invention relates to a nitrogen-containing heterocyclic compound, its preparation method, and application, belonging to the technical field of heterocyclic compound synthesis. This method solves the problem that existing methods for synthesizing indolemaleimide derivatives require a step-by-step process, resulting in low reaction efficiency and high energy consumption. The preparation method comprises the following steps: Step 1: adding indoleacetamide and a nucleophilic reagent to a mixed solution for reaction; Step 2: post-processing to obtain a nitrogen-containing heterocyclic compound; the mixed solution comprises a base, an additive, and an organic solvent; the base comprises one of triethylamine (Et3N), N,N-diisopropylethylamine, pyridine, and 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, to nitrogen-containing heterocyclic compounds and preparation methods and applications thereof, and in particular to an indolemaleimide derivative and a preparation method thereof. Background Art

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

[0003] Maleimide and indole, as advantageous structural skeletons, have wide applications in drug development, agrochemical research, and advanced material design.

[0004] Existing methods for synthesizing indolemaleimide derivatives involve a step-by-step process, resulting in low reaction efficiency and high energy consumption. Furthermore, existing processes require the use of transition metal catalysts, which pose drawbacks such as high cost and the presence of metal residues in the product. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a nitrogen-containing heterocyclic compound and its preparation method and application, which can solve at least one of the following technical problems: (1) The existing method for synthesizing indolemaleimide derivatives needs to be carried out in steps, resulting in low reaction efficiency and high energy consumption; (2) The existing process requires the use of transition metal catalysts, which is costly and contains metal residues in the product.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a nitrogen-containing heterocyclic compound, comprising the following steps:

[0008] Step 1: Add indoleacetamide and nucleophilic reagent to the mixed solution and react;

[0009] Step 2: post-treatment to obtain a nitrogen-containing heterocyclic compound;

[0010] The mixed solution includes alkali, additives and organic solvent;

[0011] The base includes one of triethylamine (Et3N), N,N-diisopropylethylamine, pyridine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0012] Optionally, the indoleacetamide has a structure as shown in structural formula 1a:

[0013] ;

[0014] 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.

[0015] Optionally, the nucleophilic reagent is a phosphorus ylide reagent, including one of an α-ester phosphorus ylide reagent and an α-acetylphenyl phosphorus ylide reagent.

[0016] Optionally, the α-ester phosphonium ylide reagent has a structure as shown in structural formula 2a:

[0017] ;

[0018] In the formula, R2 is selected from any one of hydrogen, methyl, ethyl and n-propyl.

[0019] Optionally, the α-acetylphenylphosphine ylide reagent has a structure as shown in structural formula 2b:

[0020] ;

[0021] Wherein, R is selected from an electron donating functional group or an electron withdrawing functional group.

[0022] Optionally, the electron-donating functional group is selected from any one of hydrogen, methoxy and methyl; and the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro and cyano.

[0023] 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).

[0024] Optionally, the nucleophilic reagent further comprises an α-cyclic lactone phosphorus ylide reagent.

[0025] In a second aspect, the present invention provides a nitrogen-containing heterocyclic compound prepared by the above method.

[0026] In a third aspect, the present invention provides the above-mentioned preparation method and the use of the above-mentioned nitrogen-containing heterocyclic compound in the preparation of anticancer drugs.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] (1) The present invention compresses the traditional multi-step reaction into a single-step one-pot process by jointly adjusting the reaction raw materials and the reaction system, thereby improving the reaction efficiency and reducing energy consumption.

[0029] (2) The present invention optimizes the reaction system to include a mixed solution of alkali, additives and organic solvents, and optimizes the types of alkali, additives and organic solvents, so that the reaction can be carried out without adding expensive transition metal catalysts, thereby reducing production costs and leaving no metal residue in the product.

[0030] (3) The reaction conditions of the present invention are mild and can be carried out in an air environment at normal pressure. No deoxygenation or low-temperature reaction environment is required, thus reducing production costs.

[0031] (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 large steric groups at the α-position (such as naphthalene ring), achieving dynamic functional group compatibility in the same system, solving the problem of insufficient functional group compatibility in existing methods, and achieving broad substrate applicability.

[0032] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages may become obvious from the description or be understood through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0034] Unless otherwise specified, the methods in the present invention are all conventional methods. The raw materials mentioned above can be obtained from commercial sources unless otherwise specified.

[0035] Figure 1 This is the hydrogen spectrum of the product 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3a) in the example;

[0036] Figure 2 Carbon spectrum of the product 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3a) in the example;

[0037] Figure 3 The product 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (4a) in the example has a hydrogen spectrum;

[0038] Figure 4 Carbon spectrum of the product 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrol-2-one (4a) in the example;

[0039] Figure 5 Hydrogen spectrum of product 3b;

[0040] Figure 6 Carbon spectrum of product 3b;

[0041] Figure 7 Proton spectrum of product 3c;

[0042] Figure 8 Product 3c carbon spectrum;

[0043] Figure 9 Product 3d hydrogen spectrum;

[0044] Figure 10 3d carbon spectrum of the product;

[0045] Figure 11 Hydrogen spectrum of product 3e;

[0046] Figure 12 Product 3e carbon spectrum;

[0047] Figure 13 Product 3f hydrogen spectrum;

[0048] Figure 14 Product 3f carbon spectrum;

[0049] Figure 15 3f NMR fluorine spectrum of the product;

[0050] Figure 16 Hydrogen spectrum of product 3g;

[0051] Figure 17 Carbon spectrum of product 3g;

[0052] Figure 18 Product 3h hydrogen spectrum;

[0053] Figure 19 Product 3h carbon spectrum;

[0054] Figure 20 Hydrogen spectrum of product 4b;

[0055] Figure 21 Carbon spectrum of product 4b;

[0056] Figure 22 NMR fluorine spectrum of product 4b;

[0057] Figure 23 Hydrogen spectrum of product 4c;

[0058] Figure 24 Product 4c carbon spectrum;

[0059] Figure 25 Product 4d hydrogen spectrum;

[0060] Figure 26 Product 4d carbon spectrum;

[0061] Figure 27 Hydrogen spectrum of product 4e;

[0062] Figure 28 Product 4e carbon spectrum;

[0063] Figure 29 Product 4f hydrogen spectrum;

[0064] Figure 30 Product 4f carbon spectrum;

[0065] Figure 31 Hydrogen spectrum of product 4g;

[0066] Figure 32 Carbon spectrum of product 4g;

[0067] Figure 33 NMR fluorine spectrum of product 4g;

[0068] Figure 34 Product 4h hydrogen spectrum;

[0069] Figure 35 Product 4h carbon spectrum;

[0070] Figure 36 Hydrogen spectrum of product 4i;

[0071] Figure 37 Product 4i carbon spectrum;

[0072] Figure 38 Hydrogen spectrum of product 4j;

[0073] Figure 39 Carbon spectrum of product 4j;

[0074] Figure 40 Product 4k hydrogen spectrum;

[0075] Figure 41 Product 4k carbon spectrum;

[0076] Figure 42 Hydrogen spectrum of product 4l;

[0077] Figure 43 Carbon spectrum of product 4l. DETAILED DESCRIPTION

[0078] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0079] In a first aspect, the present invention provides a method for preparing a nitrogen-containing heterocyclic compound, specifically, a method for preparing an indolemaleimide derivative, comprising the following steps:

[0080] Step 1: Add indoleacetamide and nucleophilic reagent to the mixed solution and react;

[0081] Step 2: Post-treatment to obtain indolemaleimide derivatives.

[0082] Specifically, indoleacetamide has a structure as shown in structural formula 1a:

[0083] ;

[0084] 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.

[0085] The nucleophilic reagent is a phosphine ylide reagent, including one of an α-ester phosphine ylide reagent and an α-acetylphenyl phosphine ylide reagent.

[0086] When the nucleophilic reagent is an α-ester phosphorus ylide reagent, it has a structure as shown in structural formula 2a:

[0087] ;

[0088] In the formula, R2 is selected from any one of hydrogen, methyl, ethyl and n-propyl.

[0089] The reaction equation of indoleacetamide and α-ester phosphorus ylide reagent is as follows:

[0090] ;

[0091] The indolemaleimide derivative obtained by the reaction has a structure as shown in Structural Formula 3:

[0092] ;

[0093] 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; and R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl. The specific structural formula is as follows:

[0094] ;

[0095] It should be noted that the percentage after the product number is the isolated yield.

[0096] When the nucleophilic reagent is an α-acetylphenylphosphine ylide reagent, it has a structure as shown in structural formula 2b:

[0097] ;

[0098] 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 and methyl; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro and cyano.

[0099] The reaction equation of indoleacetamide and α-acetylphenylphosphine ylide reagent is as follows:

[0100] ;

[0101] The indolemaleimide derivative obtained by the reaction has a structure as shown in Structural Formula 4:

[0102] ;

[0103] 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, or 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:

[0104] .

[0105] It should be noted that the percentage after the product number is the isolated yield.

[0106] 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.

[0107] The mixed solution includes an alkali, an additive and an organic solvent.

[0108] The base includes one of triethylamine (Et3N), N,N-diisopropylethylamine (DIPEA), pyridine, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), preferably triethylamine.

[0109] 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).

[0110] The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, and chloroform.

[0111] More specifically, when the nucleophile is an α-ester phosphorus 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.

[0112] The molar ratio of indoleacetamide to α-ester phosphine ylide reagent is (0.5-2):1, for example, 1:2, 1:1, 2:1.

[0113] The mixed solution includes triethylamine, potassium dihydrogen phosphate, and an organic solvent. The molar ratio of indoleacetamide to triethylamine is 1:(2-4), for example, 1:2, 1:3, or 1:4. The molar ratio of indoleacetamide to potassium dihydrogen phosphate is 1:(4-6), for example, 1:4, 1:5, or 1:6. The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, and chloroform. The molar volume ratio of indoleacetamide to the organic solvent is (0.1-0.2):1, where moles are expressed in mmol and volumes are expressed in mL.

[0114] When the nucleophile is an α-acetylphenylphosphine 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.

[0115] The molar ratio of indoleacetamide to α-acetylphenylphosphine ylide reagent is (3-1):2, for example, 3:2, 1:1, 1:2.

[0116] The mixed solution includes triethylamine, zinc chloride and an organic solvent.

[0117] The molar ratio of the α-acetylphenyl phosphonium ylide reagent to triethylamine is 1:(2-4), for example, 1:2, 1:3, or 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, or 1:3. The organic solvent includes one of tetrahydrofuran (THF), acetonitrile (MeCN), 1,4-dioxane, and chloroform. THF is preferred. The molar volume ratio of the α-acetylphenyl phosphonium ylide reagent to the organic solvent is (0.1-0.2):1, where moles are expressed in mmol and volumes are expressed in mL.

[0118] In step 2, post-processing includes concentration and purification. Specifically, it includes: concentrating the reaction mixture of step 1 under vacuum to obtain a residue, purifying the residue by silica gel column flash chromatography, eluting, and obtaining the product indolemaleimide 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.

[0119] The possible reaction mechanism of the present invention is as follows:

[0120] ;

[0121] First, substrate 1a undergoes a coordinated deprotonation and elimination reaction in the presence of triethylamine to yield the α-lactam intermediate Int-1, which isomerizes to Int-2. Subsequently, a phosphine ylide reagent 2 reacts with Int-2 to generate the zwitterionic intermediate Int-3, whose nitrogen anion attacks the carbonyl group to undergo a 5-exo cyclization reaction to yield Int-4. When R3 is a benzene ring, Int-4 undergoes proton transfer and elimination of triphenylphosphine to yield the hydroxylated product 4. When R3 is an ethoxy group, the hydroxylated product undergoes further deprotonation, eliminating an ethoxy anion to yield the maleimide derivative 3.

[0122] In summary, the present invention utilizes indoleacetamide and a phosphine ylide reagent containing an α-carbonyl group in the presence of triethylamine to achieve a cascade olefination / cyclization reaction. The nucleophilic phosphine reagent containing an α-ester group yields an indolemaleimide derivative: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (product 3); the phosphine ylide reagent containing an α-acetylphenyl group then yields a hydroxylated unsaturated alcohol: 5-hydroxy-5-phenyl-1-methyl-3-(1-methylindol-3-yl)pyrrole-2-one (product 4). This reaction is simple to operate, does not require the addition of expensive transition metals, and has a wide range of substrate applicability. This invention will help expand the application of nucleophilic phosphine reagents in the synthesis of nitrogen heterocycles, providing an effective new method for the synthesis of heterocyclic compounds.

[0123] In a second aspect, the present invention provides an indolemaleimide derivative prepared by the above-mentioned preparation method, which has a structure as shown in Structural Formula 4:

[0124] ;

[0125] 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, or 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:

[0126] .

[0127] It should be noted that the percentage after the product number is the isolated yield.

[0128] Alternatively, the indolemaleimide derivative has a structure as shown in Structural Formula 3:

[0129] ;

[0130] 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; and R2 is selected from any one of hydrogen, methyl, ethyl, and n-propyl. The specific structural formula is as follows:

[0131] .

[0132] It should be noted that the percentage after the product number is the isolated yield.

[0133] In the present invention, the indole maleimide derivative having structural formula 4 has an inhibitory effect on the proliferation of both human leukemia cells (K562) and prostate cancer cells (PC-3). Specifically, the IC50 for human leukemia cells (K562) is 21.6-33.0µmol·L -1 The IC50 for prostate cancer cells (PC-3) is 15.1-29.1µmol·L -1 .

[0134] Among them, the inhibitory activities of products 4b and 4g against K562 were comparable to those of cisplatin, while the inhibitory activities of the remaining products were slightly weaker than those of cisplatin.

[0135] Products 4b, 4c, 4d, 4e, and 4g showed better inhibitory activity against PC-3 than cisplatin, while the inhibitory activity of the remaining products was comparable to that of cisplatin. Product 4g showed the strongest inhibitory activity against PC-3 (IC50 = 15.1 µmol·L -1 ), which is 1.71 times that of cisplatin.

[0136] In the present invention, the indole maleimide derivative having structural formula 3 has an inhibitory effect on the proliferation of both human leukemia cells (K562) and prostate cancer cells (PC-3). Specifically, the IC50 for human leukemia cells (K562) is 11.2-26.1µmol·L -1 The IC50 for prostate cancer cells (PC-3) is 16.1-26.2µmol·L -1 .

[0137] Among them, products 3b, 3c, 3d, 3f, 3g, and 3h showed significantly better inhibitory activity against K562 than cisplatin, while the inhibitory activity of the remaining products was comparable to that of cisplatin. Product 3f showed the strongest inhibitory activity against K562 (IC50 = 11.2 µmol·L-1), which was 2.11 times that of cisplatin.

[0138] 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.

[0139] 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.

[0140] 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).

[0141] Example 1

[0142] 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% respectively (No. 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% (No. 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).

[0143] Table 1 Optimization of reaction conditions a

[0144] ;

[0145] 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).

[0146] b 1 H NMR yields were determined using 4-methylbenzophenone as the internal standard;

[0147] c 1a:2a = 2:1;

[0148] d 1a:2a = 1:1;

[0149] e 40℃ for 24 hours;

[0150] f Isolation yield.

[0151] It should be noted that in the reaction of No. 7 in Table 1, the volume ratio of the eluent petroleum ether:ethyl acetate when determining the separation yield was 10:1.

[0152] 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.

[0153] The reaction equation of the present embodiment is as follows:

[0154] .

[0155] Example 2

[0156] This example is basically the same as Example No. 7 in Table 1, except that the reaction temperature is 70°C, the reaction time is 5 hours, and the product 3a is 1 The H NMR yield was 57%.

[0157] Example 3

[0158] This example is basically the same as Example No. 7 in Table 1, except that the reaction temperature is 120°C, the reaction time is 3 hours, and the product 3a is 1 The H NMR yield was 55%.

[0159] Example 4

[0160] This example is basically the same as Example No. 7 in Table 1, except that the base used is N,N-diisopropylethylamine (DIPEA), and the product 3a 1 The H NMR yield was 43%.

[0161] Comparative Example 1

[0162] This comparative example is basically the same as Example No. 7 in Table 1, except that the reaction temperature is 65°C, the reaction time is 5 hours, and the product 3a is 1 The H NMR yield was 26%.

[0163] Example 5

[0164] In this example, the molar ratio of 1a to 2a was 1:2, with 1a used in an amount of 0.2 mmol and 2a in an amount of 0.4 mmol (2 equivalents). The organic solvent used was 1.0 mL of chloroform, 1 mmol (5 equivalents) of KH2PO4, and 0.6 mmol (3 equivalents) of Et3N. The reaction temperature was 80°C, and the reaction time was 4 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 volume ratio of petroleum ether to ethyl acetate as the eluent of 10:1.

[0165] 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.

[0166] The reaction equation of the present embodiment is as follows:

[0167] ;

[0168] This example expands the substrate range of α-ester phosphine ylide reagents (Table 2). Some long-chain α-ester phosphine ylide reagents can obtain indole maleimide derivatives in good yields, product 3: 1-methyl-3-(1-methylindol-3-yl)pyrrole-2,5-dione (3b-3d). It is worth noting that when α-cyclic lactone phosphine ylide reagents are used as nucleophiles, the CO bond is broken and the ring-opened product (3e) is obtained in a yield of 43%. The structural formula 2c of the α-cyclic lactone phosphine ylide reagent is as follows:

[0169] .

[0170] Table 2 Reaction of different indoleacetamides with different α-ester phosphine ylide reagents

[0171] ;

[0172] Note: The phosphine ylide used to synthesize product 3e is not an α-ester phosphine ylide, but an α-cyclic lactone phosphine ylide of formula 2c. The yields in the table refer to isolated yields.

[0173] Example 6

[0174] 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.

[0175] 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.

[0176] The reaction equation of the present embodiment is as follows:

[0177] .

[0178] Table 3 Reaction of different α-acetylphenylphosphine ylide reagents

[0179] ;

[0180] 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.

[0181] 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).

[0182] Depend on Figure 1-Figure 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.

[0183] Depend on Figure 3-Figure 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.

[0184] Specifically, 4a was obtained as a white solid (42 mg, 66% yield), Rf = 0.44 (PE:EA = 2:1).

[0185] 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).

[0186] 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.

[0187] in addition, Figure 5-Figure 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.

[0188] Application Example 1

[0189] This application example tests the in vitro anticancer activity of some of the products synthesized in the examples.

[0190] 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.

[0191] MTT method: dissolve the target product in a small amount of DMSO to prepare 10mmol·L -1 The stock solution was diluted to the required concentrations using RPMI1640 culture medium (GIBICO, Invitrogen) containing 10% fetal bovine serum, which were: 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 The final DMSO concentration was maintained below 0.1%. Human leukemia cells (K562) and prostate cancer cells (PC-3) were cultured in RPMI1640 medium supplemented with 10% fetal bovine serum in a 5% CO2 incubator at 37°C. Cell proliferation and growth inhibition were assessed using the MTT assay. The number of cells was adjusted to achieve an absorbance of 1.3–2.2 at 570 nm. Cells were treated with the target product test solution at each of the six concentrations for 72 hours. The experiment was repeated three times in at least three replicates for each concentration. Statistical analysis was performed using GraphPad Prism 5.0 software to determine IC50 values.

[0192] Table 4 Anticancer activity of product 3 synthesized in the present invention

[0193] ;

[0194] Note: IC50 (half inhibitory concentration) refers to the drug concentration required to inhibit 50% cell growth. The lower the IC50 value, the stronger the drug activity.

[0195] As can be seen from Table 4, the IC50 of product 3 of the present invention against human leukemia cells (K562) is 11.2-26.1 μmol·L -1 The IC50 for prostate cancer cells (PC-3) is 16.1-26.2µmol·L -1 , indicating that product 3 of the present invention inhibits the proliferation of both tumor cells. Products 3b, 3c, 3d, 3f, 3g, and 3h exhibited significantly superior inhibitory activity against K562 compared to cisplatin, while the remaining products exhibited comparable inhibitory activity to cisplatin. Product 3f exhibited the strongest inhibitory activity against K562 (IC50 = 11.2 µmol·L-1), 2.11 times that of cisplatin.

[0196] Table 4 also shows that products 3a, 3g, 3h, and 3f exhibited 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 exhibited the strongest inhibitory activity against PC-3 (IC50 = 16.1 µmol·L-1), which was 1.60 times that of cisplatin.

[0197] Table 5 Anticancer activity of product 4 synthesized in the present invention

[0198] ;

[0199] 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.

[0200] 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.

[0201] 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.

[0202] 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.

[0203] 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: The steps include: Step 1: Add indoleacetamide and nucleophilic reagent to the mixed solution and react; Step 2: post-treatment to obtain a nitrogen-containing heterocyclic compound; The mixed solution includes alkali, additives and organic solvent; The base is selected from one of triethylamine (Et3N), N,N-diisopropylethylamine, pyridine, and 1,8-diazabicyclo[5.4.0]undec-7-ene; The indoleacetamide 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 nucleophilic reagent is a phosphorus ylide reagent, selected from one of an α-ester phosphorus ylide reagent and an α-acetylphenyl phosphorus 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, 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, methoxy, and methyl; the electron-withdrawing functional group is selected from any one of fluorine, chlorine, bromine, iodine, phenyl, trifluoromethyl, nitro, and cyano; 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, 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 methyl, ethyl, and n-propyl; The α-ester phosphine ylide reagent has a structure as shown in structural formula 2a: ； Wherein, R2 is selected from any one of methyl, ethyl and n-propyl; The α-acetylphenylphosphine 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, 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; The additive is selected from one of dipotassium hydrogen phosphate (K2HPO4), potassium dihydrogen phosphate (KH2PO4), glacial acetic acid, 4-dimethylaminopyridine (DMAP), sodium carbonate and zinc chloride (ZnCl2).

2. A nitrogen-containing heterocyclic compound, characterized in that The method according to claim 1 is used to prepare the product.

3. Use of the nitrogen-containing heterocyclic compound according to claim 2 in the preparation of drugs against human leukemia cells K562 and prostate cancer cells PC-3.

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