5-alkylene-2-pyrrolidone compound as well as preparation method and application thereof

Abstract

The invention discloses a 5-alkylene-2-pyrrolidone compound as well as a preparation method and application thereof, and belongs to the technical field of organic synthesis. According to the invention, a series of 5-alkylene-2-pyrrolidone compounds are prepared by utilizing tandem reaction of acetylenic acid and an amine nucleophilic reagent, and the method has the advantages of wide substrate application range, high regioselectivity, good yield, good functional group tolerance, economic reaction steps, mild reaction conditions and the like. The method can be easily amplified to a gram scale, and the practicability of the method can be proved. In addition, the method disclosed by the invention can also be applied to structural modification of alkaloid, and has a wide application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic synthesis, and in particular relates to a 5-alkylene-2-pyrrolidone compound, a preparation method and an application thereof. Background Art

[0002] 5-Alkylmethylenepyrrolidin-2-ones are important scaffolds for many complex natural products, particularly those found in fungal metabolites, and possess diverse biological activities. For example, the marine alkaloid Microsclerodermin E and the hybrid peptide Hybrubin A both share a 5-alkylmethylenepyrrolidin-2-one skeleton. Microsclerodermin E exhibits excellent antioxidant activity, while Hybrubin A exhibits excellent antibacterial activity. Importantly, 5-alkylmethylenepyrrolidin-2-one derivatives are versatile precursors to N-acylimide ion intermediates, enabling stereoselective construction of polycyclic frameworks and spirocyclic structures. However, current synthetic methods for 5-alkylmethylenepyrrolidin-2-ones generally face challenges. For example, traditional multi-step syntheses require harsh reaction conditions and cumbersome synthetic steps. Hydrocarbon activation strategies are limited by expensive starting materials, demanding reaction conditions, and the difficulty of removing directing groups. Therefore, it is crucial to develop synthetic methods with broad substrate applicability, excellent yields, and mild reaction conditions. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a 5-alkylene-2-pyrrolidone compound, so as to solve the technical problems of complicated synthesis steps and harsh reaction conditions of the existing 5-alkylene-2-pyrrolidone compound.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide a 5-alkylene-2-pyrrolidone compound, the general structural formula of which is: ; Among them, R 1 is benzyl, phenethyl, arylethyl, 1-naphthylmethyl, phenyl, alkyl or propargyl; R 2 is hydrogen, halogen, alkyl, alkoxy, nitro, cyano or trifluoromethyl.

[0005] On the basis of the above technical solution, the present invention can also be improved as follows: Further, the structural formula of the 5-alkylene-2-pyrrolidone compound is:

[0006]

[0007] The present invention also discloses a method for preparing the above-mentioned 5-alkylene-2-pyrrolidone compound, comprising the following steps: dissolving an acetylenic acid, an amine nucleophile, and a catalyst in an organic solvent at a molar ratio of 0.5-1.5:1-2:0.01-0.1, then reacting at 90-120°C for 7-10 hours, activating the acetylenic acid with the catalyst to generate a C2 synthon-5-alkylene-substituted lactone intermediate in situ, releasing the catalyst to participate in the next catalytic cycle, and then attacking the generated lactone intermediate with the amine nucleophile to undergo a nucleophilic substitution reaction, tautomerism, a second nucleophilic cyclization, and dehydration, thereby finally obtaining the 5-alkylene-2-pyrrolidone compound; The structural formula of acetylenic acid is The structural formula of the amine nucleophile is ; where R 1 is benzyl, phenethyl, arylethyl, 1-naphthylmethyl, phenyl, alkyl or propargyl; R 2 is hydrogen, halogen, alkyl, alkoxy, nitro, cyano or trifluoromethyl.

[0008] On the basis of the above technical solution, the present invention can also be improved as follows: Furthermore, the molar ratio of the alkyne acid, the amine nucleophile and the catalyst is 1:1.5:0.05.

[0009] Furthermore, the alkynoic acid is 5-phenylpent-4-ynoic acid, 5-(4-methoxyphenyl)-4-pentynoic acid, 5-(3-methylphenyl)-4-pentynoic acid, 5-(4-methylphenyl)-4-pentynoic acid, 5-(2-fluorophenyl)-4-pentynoic acid, 5-(4-fluorophenyl)-4-pentynoic acid, 5-(3-chlorophenyl)-4-pentynoic acid, 5-(4-nitrophenyl)-4-pentynoic acid, 5-(4-cyanophenyl)-4-pentynoic acid, phenyl)-4-pentynoic acid, 5-(4-trifluoromethylphenyl)-4-pentynoic acid or 5-(thiophen-2-yl)-4-pentynoic acid; the amine nucleophile is 2-phenylethylamine, 3,4-dimethoxyphenylethylamine, 2-methoxyphenylethylamine, 3-methoxyphenylethylamine, 3,4-methylenedioxyphenylethylamine, 4-trifluoromethylphenylethylamine, 4-fluorophenylethylamine, 2-chlorophenylethylamine, 4-chlorophenylethylamine, 4-bromophenylethylamine, 2-(1 H 1-pyrrol-1-yl)-1-ethylamine, 2-(thiophen-2-yl)-1-ethylamine, 2-(thiophen-3-yl)-1-ethylamine, 2-methoxybenzylamine, 4-methoxybenzylamine, benzylamine, 3-chloro-4-fluorobenzylamine, 3-fluorobenzylamine, 4-bromobenzylamine, 4-cyanobenzylamine, 1-naphthylmethylamine, 2,3-dimethylaniline, n-propylamine, or propargylamine.

[0010] Furthermore, the catalyst is AgNO3, Ag2CO3, AgOAc, AgOTf, Pd(OAc)2, PdCl2(PPh3)2, Cu(OAc)2, CuCl2, CuI, Zn(OAc)2, [RuCl2( p-cym )]2, Mn(OAc)2, Co(OAc)2, Co(acac)2, NiCl2, Ni(OTf)2, Au(PPh3)Cl or Au(PPh3)OTf.

[0011] Furthermore, the catalyst is AgOTf or Au(PPh3)OTf.

[0012] Furthermore, the organic solvent is acetonitrile, toluene, 1,2-dichloroethane, 1,4-dioxane, ethanol or dimethyl sulfoxide.

[0013] Furthermore, the organic solvent is acetonitrile.

[0014] Furthermore, the reaction temperature was 100° C. and the reaction time was 8 h.

[0015] The invention also discloses the application of the 5-alkylene-2-pyrrolidone compound in the preparation of antibacterial drugs.

[0016] The present invention has the following beneficial effects: the method has the advantages of a wide substrate applicability, high regioselectivity, good yield, good functional group tolerance, economical reaction steps, and mild reaction conditions. The method is easily scalable to gram-scale production, demonstrating its practicality. Furthermore, the method can also be applied to the structural modification of alkaloids, showing broad application prospects. DETAILED DESCRIPTION

[0017] The specific embodiments of the present invention are described below to facilitate understanding of the present invention by those skilled in the art. In the examples, where specific conditions are not specified, the experiments were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. It is obvious to those skilled in the art that various modifications are within the spirit and scope of the present invention as defined and determined by the appended claims, and all inventions and creations utilizing the present invention are protected.

[0018] Example 1 A method for preparing a 5-alkylene-2-pyrrolidone compound, the reaction equation is as follows: , Specifically, the process includes dissolving 0.5 mmol of 5-phenylpent-4-ynoic acid, 1 mmol of 2-phenylethylamine, and 0.1 mmol of AgOAc in 2 mL of toluene, reacting the mixture at 90° C. for 10 hours, removing the solvent, and separating and purifying the resulting residue by flash chromatography on silica gel to obtain a 5-alkylene-2-pyrrolidone compound.

[0019] Example 2 A method for preparing a 5-alkylene-2-pyrrolidone compound, the reaction equation is as follows: , Specifically, the method includes the following steps: dissolving 1.5 mmol 5-phenylpent-4-ynoic acid, 2 mmol 2-phenylethylamine and 0.01 mmol Ag2CO3 in 2 mL 1,2-dichloroethane, and then reacting the mixture at 120°C for 7 hours. After removing the solvent, the obtained residue is separated and purified by flash chromatography on silica gel to obtain the product 5-alkylene-2-pyrrolidone compound.

[0020] Example 3 A method for preparing a 5-alkylene-2-pyrrolidone compound, the reaction equation is as follows: , Specifically, the method comprises the following steps: dissolving 1 mmol of 5-phenylpent-4-ynoic acid, 1.5 mmol of 2-phenylethylamine and 0.05 mmol of Au(PPh3)OTf in 2 mL of acetonitrile, reacting at 100°C for 8 hours, removing the solvent, and separating and purifying the obtained residue by flash chromatography on silica gel to obtain a colorless oily substance, i.e., the product 5-alkylene-2-pyrrolidone compound (3aa, ( E )-5-benzylidene-1-phenethylpyrrolidin-2-one), the product mass was 46.8 mg, and the yield was 84%.

[0021] Example 4 The difference between this embodiment and embodiment 3 is that the amount of catalyst Au(PPh3)OTf is adjusted to 2.5 mol% of 5-phenylpent-4-ynoic acid, and the other implementation conditions are the same as those in embodiment 3, and the final product 5-alkylene-2-pyrrolidone compound is obtained with a yield of 46%.

[0022] Example 5 The difference between this embodiment and embodiment 3 is that the catalyst Au(PPh3)OTf is replaced by AgOTf, and the other implementation conditions are the same as those of embodiment 3. Finally, a colorless oily substance is obtained, i.e., the product 5-alkylidene-2-pyrrolidone compound (3aa, ( E)-5-benzylidene-1-phenethylpyrrolidin-2-one), the product mass was 44.4 mg, and the yield was 80%.

[0023] Compound 3aa was characterized and the results were: 1 H NMR (500 MHz, CDCl3) δ 7.37-7.29 (m,4H), 7.27 (s, 1H), 7.27-7.20 (m, 4H), 7.19-7.13 (m, 1H), 5.80 (s, 1H), 3.87-3.77 (m, 2H), 3.02-2.87 (m, 4H), 2.57-2.47 (m, 2H); 13 C NMR (125 MHz, CDCl3) δ175.18, 141.91, 138.51, 136.83, 128.92, 128.71, 128.64, 127.78, 126.76,125.63, 102.88, 41.59, 32.89, 29.08, 24.09; LRMS (ESI) m / z : 278 [M+H] + ; HRMS(ESI) m / z calculated for C 19 H 19 NO+H + 278.1539, found: 278.1537. Example 6 The difference between this example and Example 5 is that the reaction time is adjusted to 10 hours, and the other implementation conditions are the same as Example 3. Finally, the product 5-alkylidene-2-pyrrolidone compound is obtained with a yield of 78%.

[0024] Example 7 The difference between this example and Example 5 is that the reaction temperature is adjusted to 120° C., and the other implementation conditions are the same as Example 3. Finally, the product 5-alkylidene-2-pyrrolidone compound is obtained with a yield of 63%.

[0025] Comparative Example The difference between this comparative example and Example 3 is that the catalyst was omitted, and the other implementation conditions were the same as those in Example 3. Ultimately, no 5-alkylidene-2-pyrrolidone compound was obtained.

[0026] Experimental Example 1 Taking Example 3 as an example, the type of catalyst was changed to explore its effect on the yield of 5-alkylene-2-pyrrolidone compounds. The results are shown in Table 1.

[0027] Table 1 Effect of catalyst on yield

[0028] It can be seen from Table 1 that AgOTf and Au(PPh3)OTf have better catalytic effects on the reaction of the present invention.

[0029] Experimental Example 2 Taking Example 5 as an example, the effect of changing the type of organic solvent on the yield of 5-alkylene-2-pyrrolidone compound was explored. The results are shown in Table 2.

[0030] Table 2 Effect of organic solvents on yield

[0031] It can be seen from Table 2 that when the organic solvent is acetonitrile, the yield of the reaction product is the highest.

[0032] Experimental Example 3 Set the acetylenic acid substrate to 0.2 mmol, the amine nucleophile (2-phenylethylamine) to 0.3 mmol, the catalyst addition amount to 5 mol% of the acetylenic acid substrate (AuPPh3OTf / AgOTf), 2.0 mL of acetonitrile, the reaction temperature to 100 ° C, and the reaction time to 8 h. According to the following reaction formula, the substrate applicability of acetylenic acid was explored.

[0033] , Wherein [A] represents the yield of the product when the catalyst is AuPPh3OTf, and [B] represents the yield of the product when the catalyst is AgOTf.

[0034] 1. Compound 3ab: ( E )-5-(4-methoxybenzylidene)-1-phenethylpyrrolidin-2-one, the structural formula is: ; When the alkyne acid substrate was 5-(4-methoxyphenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 2:1, v:v) to obtain a yellow oil. When the catalyst was AuPPh3OTf, the product mass was 42.9 mg with a yield of 70%; when the catalyst was AgOTf, the product mass was 45.6 mg with a yield of 74%.

[0035] Compound 3ab was characterized, and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.34-7.30 (m,2H), 7.29-7.26 (m, 2H), 7.26-7.22 (m, 1H), 7.18 (d,J = 8.7 Hz, 2H), 6.89 (d, J =8.7 Hz, 2H), 5.76 (s, 1H), 3.85-3.79 (m, 5H), 2.97-2.89 (m, 4H), 2.56-2.50(m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.13, 157.62, 140.30, 138.61, 129.39,128.95, 128.91, 128.72, 126.75, 114.14, 102.43, 55.44, 41.58, 32.92, 29.17,23.95. LRMS (ESI) m / z : 308 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO2+H + 308.1645, found: 308.1646. 2. Compound 3ac: ( E )-5-(3-methylbenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is: ; When the alkyne acid substrate was 5-(3-methylphenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 2:1, v:v) to obtain a white solid. When the catalyst was AuPPh3OTf, the product mass was 46.2 mg with a yield of 79%; when the catalyst was AgOTf, the product mass was 49.7 mg with a yield of 85% and a melting point of 94-95°C.

[0036] Compound 3ac was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.31 (m,2H), 7.30-7.27 (m, 2H), 7.26-7.21 (m, 2H), 7.10-7.05 (m, 2H), 7.00 (d, J= 7.5Hz, 1H), 5.79 (s, 1H), 3.88-3.79 (m, 2H), 3.02-2.97 (m, 2H), 2.95-2.90 (m,2H), 2.56-2.52 (m, 2H), 2.36 (s, 3H); 13 C NMR (150 MHz, CDCl3) δ 175.23,141.74, 138.53, 138.21, 136.76, 128.95, 128.72, 128.70, 128.56, 126.77,126.48, 124.76, 102.99, 41.59, 32.89, 29.13, 24.15, 21.69. LRMS (ESI) m / z : 292[M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO+H + 292.1696, found: 292.1697. 3. Compound 4 3ad: ( E )-5-(4-methylbenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is: ; When the alkyne acid substrate was 5-(4-methylphenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 2:1, v:v) to obtain a yellow oil. When AuPPh3OTf was used as the catalyst, the product mass was 50.5 mg with a yield of 87%; when AgOTf was used as the catalyst, the product mass was 48.3 mg with a yield of 83%.

[0037] Compound 3ad was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.46-7.42 (m,2H), 7.41-7.33 (m, 4H), 7.27-7.26 (m, 3H), 5.90 (s, 1H), 3.97-3.91 (m, 2H), 3.10-3.06 (m, 2H), 3.05-3.02 (m, 2H), 2.66-2.62 (m, 2H), 2.46 (s, 3H); 13C NMR(150 MHz, CDCl3) δ 175.22, 141.16, 138.57, 135.36, 133.89, 129.37, 128.95,128.72, 127.70, 126.76, 102.83, 41.58, 32.90, 29.14, 24.07, 21.21. LRMS (ESI) m / z : 292 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO+H + 292.1696, found:292.1693. 4. Compound 3ae: ( E )-5-(2-fluorobenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is: ; When the alkyne acid substrate was 5-(2-fluorophenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a white solid. When the catalyst was AuPPh3OTf, the product mass was 43.3 mg with a yield of 73%; when the catalyst was AgOTf, the product mass was 47.4 mg with a yield of 80% and a melting point of 98-100°C.

[0038] Compound 3ae was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.27 (m,5H),7.26-7.22 (m, 1H), 7.20-7.15 (m, 1H), 7.13-7.05 (m, 2H), 5.93 (s, 1H), 3.88-3.81 (m, 2H), 2.98-2.87 (m, 4H), 2.56-2.50 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ175.33, 159.94 (d, J C-F = 246.8 Hz), 143.40, 138.37, 128.96, 128.72, 128.56 (d, J C-F = 2.3 Hz), 127.31 (d, J C-F= 8.4 Hz), 126.76, 124.56 (d, J C-F = 13.1 Hz), 124.00(d, J C-F = 3.4 Hz), 115.60 (d, J C-F = 22.3 Hz), 94.67 (d, J C-F = 5.2 Hz), 41.67,32.74, 29.00, 23.78. LRMS (ESI) m / z : 296 [M+H] + ; HRMS (ESI) m / z calculated for C 19 H 18 FNO+H + 296.1445, found: 296.1447. 5. Compound 3af: ( E )-5-(4-fluorobenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is: ; When the alkyne acid substrate was 5-(4-fluorophenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a white solid. When the catalyst was AuPPh3OTf, the product mass was 46.8 mg with a yield of 79%; when the catalyst was AgOTf, the product mass was 48.9 mg with a yield of 83% and a melting point of 94-95°C.

[0039] Compound 3af was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.30 (m,2H), 7.28-7.26 (m, 2H), 7.25-7.23 (m, 1H), 7.21-7.16 (m, 2H), 7.05-7.00 (m,2H), 5.75 (s, 1H), 3.86-3.79 (m, 2H), 2.95-2.89 (m, 4H), 2.57-2.50 (m, 2H); 13 CNMR (150 MHz, CDCl3) δ 175.19, 160.88 (d, J C-F= 245.4 Hz), 141.69, 138.52,132.86 (d, J C-F = 3.3 Hz), 129.23 (d, J C-F = 7.7 Hz), 128.95, 128.75, 126.82,115.54 (d, J C-F = 21.4 Hz), 101.80, 41.65, 32.94, 29.04, 23.93. LRMS (ESI) m / z :296 [M+H] + ; HRMS (ESI) m / z calculated for C 19 H 18 FNO+H + 296.1445, found: 296.1449. 6. Compound 3ag: ( E )-5-(3-chlorobenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is ; When the alkyne acid substrate was 5-(3-chlorophenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a white solid. When the catalyst was AuPPh3OTf, the product mass was 50.7 mg with an 81% yield; when the catalyst was AgOTf, the product mass was 49.4 mg with a 79% yield, and the melting point was 97-99°C.

[0040] Compound 3ag was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.31 (m,2H), 7.29-7.26 (m, 2H), 7.26-7.24 (m, 2H), 7.23-7.20 (m, 2H), 7.15-7.09 (m,1H), 5.72 (s, 1H), 3.90-3.75 (m, 2H), 2.99-2.94 (m, 2H), 2.94-2.90 (m, 2H),2.59-2.50 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.22, 143.26, 138.74, 138.37,134.47, 129.80, 128.92, 128.75, 127.56, 126.83, 125.89, 125.54, 101.63,41.66, 32.89, 28.92, 24.12. LRMS (ESI) m / z : 314 ([M+H] + , Cl 37 ), 312 ([M+H] + ,Cl 35 ); HRMS (ESI) m / z calculated for C 19 H 18 ClNO+H + 312.1150, found: 312.1152. 7. Compound 3ah: ( E )-5-(4-nitrobenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is ; When the alkyne acid substrate was 5-(4-nitrophenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a yellow solid. When the catalyst was AuPPh3OTf, the product mass was 48.8 mg with a yield of 76%; when the catalyst was AgOTf, the product mass was 45.1 mg with a yield of 70% and a melting point of 105-106°C.

[0041] Compound 3ah was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 8.18 (d, J = 8.8Hz, 2H), 7.33 (m, 4H), 7.27 (m, 2H), 7.26 (m, 1H), 5.80 (s, 1H), 3.91-3.82(m, 2H), 3.07-3.01 (m, 2H), 2.96-2.91 (m, 2H), 2.63-2.59 (m, 2H).; 13C NMR (150MHz, CDCl3) δ 175.25, 146.42, 144.92, 144.13, 138.20, 128.91, 128.81, 127.73,126.97, 124.15, 101.38, 41.87, 33.00, 28.71, 24.65. LRMS (ESI) m / z : 323; HRMS(ESI) m / z calculated for C 19 H 18 N2O3+H + 323.1390, found: 323.1386. 8. Compound 3ai: ( E )-4-((5-oxo-1-phenylethylpyrrolidin-2-ylidene)methyl)benzonitrile, the structural formula is ; When the alkyne acid substrate was 5-(4-cyanophenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a yellow solid. When the catalyst was AuPPh3OTf, the product mass was 40.9 mg with a yield of 68%; when the catalyst was AgOTf, the product mass was 37.7 mg with a yield of 62% and a melting point of 86-88°C.

[0042] Compound 3ai was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.59 (d, J = 8.3Hz, 2H), 7.34-7.30 (m, 2H), 7.29 (d, J = 8.3 Hz, 2H), 7.26-7.22 (m, 3H), 5.74(s, 1H), 3.88-3.80 (m, 2H), 3.02-2.97 (m, 2H), 2.94-2.90 (m, 2H), 2.61-2.56(m, 2H). 13 C NMR (150 MHz, CDCl3) δ 175.22, 145.49, 141.87, 138.23, 132.39,128.89, 128.78, 127.91, 126.92, 119.31, 108.35, 101.62, 41.78, 32.94, 28.74,24.47. LRMS (ESI) m / z : 303; HRMS (ESI) m / z calculated for C 20 H 18 N2O+H + 303.1492,found: 303.1488. 9. Compound 3aj: ( E )-5-(4-trifluoromethylbenzylidene)-1-phenylethylpyrrolidin-2-one, the structural formula is ; When the alkyne acid substrate was 5-(4-trifluoromethylphenyl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a yellow solid. When the catalyst was AuPPh3OTf, the product mass was 42.5 mg with a yield of 62%; when the catalyst was AgOTf, the product mass was 46.3 mg with a yield of 67%, and the melting point was 100-102°C.

[0043] Compound 3aj was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.57 (d, J = 8.2Hz, 2H), 7.35-7.30 (m, 4H), 7.29-7.26 (m, 2H), 7.26-7.24 (m, 1H), 5.78 (s,1H), 3.91-3.80 (m, 2H), 3.02-2.97 (m, 2H), 2.96-2.91 (m, 2H), 2.60-2.54 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.26, 144.22, 140.61, 138.36, 128.93, 128.77,127.72, 127.28 (q, J C-F = 32.6 Hz), 126.88, 125.53 (q, J C-F = 3.4 Hz), 124.40 (q, J C-F = 271.8 Hz), 101.70, 41.72, 32.94, 28.88, 24.27. LRMS (ESI) m / z : 346 [M+H] + ;HRMS (ESI) m / z calculated for C 20 H 18 F3NO+H + 346.1413, found: 346.1414. 10. Compound 3ak: ( E )-1-phenylethyl-5-(thiophene-2-methylene)pyrrolidin-2-one, the structural formula is ; When the alkyne acid substrate was 5-(thiophen-2-yl)-4-pentynoic acid, the reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a yellow solid. When the catalyst was AuPPh3OTf, the product mass was 40.8 mg with a yield of 72%; when the catalyst was AgOTf, the product mass was 44.9 mg with a yield of 79% and a melting point of 119-120°C.

[0044] Compound 3ak was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.34-7.31 (m,2H), 7.29-7.26 (m, 2H), 7.26-7.23 (m, 1H), 7.19 (d, J = 5.1 Hz, 1H), 7.04-7.01(m, 1H), 6.89 (d, J = 3.4 Hz, 1H), 6.06 (s, 1H), 3.84-3.79 (m, 2H), 2.98-2.94(m, 2H), 2.93-2.89 (m, 2H), 2.61-2.58 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ175.36, 141.07, 140.23, 138.36, 128.91, 128.75, 127.29, 126.84, 124.65,123.18, 96.90, 41.62, 32.91, 28.96, 24.00. LRMS (ESI) m / z : 284 [M+H] + ; HRMS(ESI) m / z calculated for C 17 H 17 NOS+H + 284.1104, found: 284.1106. The above results show that the tandem cyclization reaction between alkyne acids and amine nucleophiles disclosed in the present invention has a wide range of applicability for alkyne acid substrates, good regioselectivity, excellent yield, good functional group tolerance, economical reaction steps, high bonding efficiency, and can efficiently synthesize 5-alkylmethylenepyrrolidin-2-one compounds.

[0045] Experimental Example 4 Set 0.2 mmol of acetyloic acid substrate (5-phenylpent-4-ynoic acid), 0.3 mmol of amine nucleophile, 5 mol% of the catalyst added (AuPPh3OTf / AgOTf) of the acetyloic acid substrate, 2.0 mL of acetonitrile, reaction temperature of 100°C, and reaction time of 8 h. According to the following reaction formula, the substrate applicability range of the amine nucleophile was explored.

[0046] , Wherein [A] represents the yield of the product when the catalyst is AuPPh3OTf, and [B] represents the yield of the product when the catalyst is AgOTf.

[0047] 1. Compound 3am: ( E )-5-benzylidene-1-(3,4-dimethoxyphenethyl)pyrrolidin-2-one, the structural formula is ; The reaction was carried out using 3,4-dimethoxyphenylethylamine as the amine nucleophile. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a light yellow oil. When AuPPh3OTf was used as the catalyst, the product yield was 46.3 mg with a yield of 69%. When AgOTf was used as the catalyst, the product yield was 45.2 mg with a yield of 67%.

[0048] Compound 3am was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.32 (m,2H), 7.27-7.24 (m, 2H), 7.21-7.15 (m, 1H), 6.84-6.79 (m, 3H), 5.82 (s, 1H), 3.89 (s, 3H), 3.87 (s, 3H), 3.84-3.81 (m, 2H), 3.01-2.96 (m, 2H), 2.91-2.85(m, 2H), 2.58-2.52 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.27, 149.04, 147.84,141.90, 136.79, 130.98, 128.66, 127.74, 125.65, 120.82, 112.08, 111.37,102.93, 56.03, 56.01, 41.63, 32.42, 29.10, 24.08. LRMS (ESI) m / z : 338 [M+H] + ;HRMS (ESI) m / z calculated for C 21 H 23 NO3+H + 338.1751, found: 338.1747. 2. Compound 3an: ( E )-5-benzylidene-1-(2-methoxyphenethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded when the amine nucleophile was 2-methoxyphenylethylamine. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a light yellow oil. When AuPPh3OTf was used as the catalyst, the product yielded 48.4 mg with a yield of 79%. When AgOTf was used as the catalyst, the product yielded 45.7 mg with a yield of 74%.

[0049] Compound 3an was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.38-7.32 (m,2H),7.29-7.24 (m, 3H), 7.24-7.20 (m, 1H), 7.20-7.16 (m,1H), 6.91 (dd, J = 14.7, 7.3Hz, 2H), 6.04 (s, 1H), 3.92 (s, 3H), 3.83-3.79 (m, 2H), 3.02-2.97 (m, 2H), 2.97-2.93 (m, 2H), 2.58-2.54 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.31,157.85, 142.09, 137.27, 130.86, 128.66, 128.17, 127.73, 126.87, 125.48,120.73, 110.36, 103.09, 55.46, 40.10, 29.23, 28.17, 24.05; LRMS (ESI) m / z : 308[M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO2+H + 308.1645, found: 308.1644. 3. Compound 3ao: ( E )-5-benzylidene-1-(3-methoxyphenethyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 3-methoxyphenylethylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a light yellow oil. When the catalyst was AuPPh3OTf, the product mass was 45.9 mg with a yield of 75%; when the catalyst was AgOTf, the product mass was 44.3 mg with a yield of 72%.

[0050] Compound 3ao was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.31 (m,2H), 7.27-7.23 (m, 3H), 7.19-7.15 (m, 1H), 6.89-6.86 (m, 1H), 6.83-6.81 (m,1H), 6.81-6.77 (m, 1H), 5.82 (s, 1H), 3.85-3.82 (m, 2H), 3.81 (s, 3H), 3.02-2.96 (m, 2H), 2.93-2.87 (m, 2H), 2.59-2.53 (m, 2H); 13C NMR (150 MHz, CDCl3) δ175.33, 159.88, 141.86, 140.08, 136.79, 129.74, 128.66, 127.79, 125.67,121.26, 114.65, 112.09, 102.98, 55.35, 41.51, 32.91, 29.11, 24.11. LRMS (ESI) m / z : 308 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO2+H + 308.1645, found:308.1642. 4. Compound 3ap: ( E )-5-benzylidene-1-(3,4-methylenedioxyphenethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded when the amine nucleophile was 3,4-methylenedioxyphenylethylamine. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 43.3 mg with a 67% yield. When AgOTf was used as the catalyst, the product yielded 45.4 mg with a 71% yield, and a melting point of 98-99°C.

[0051] Compound 3ap was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.31 (m,2H), 7.26-7.23 (m, 2H), 7.19-7.15 (m, 1H), 6.77-6.74 (m, 2H), 6.72-6.69 (m,1H), 5.93 (s, 2H), 5.79 (s, 1H), 3.81-3.75 (m, 2H), 3.01-2.96 (m, 2H), 2.86-2.81 (m, 2H), 2.57-2.51 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.23, 147.86,146.38, 141.90, 136.81, 132.25, 128.66, 127.77, 125.66, 121.82, 109.35,108.49, 102.89, 101.04, 41.79, 32.61, 29.08, 24.10. LRMS (ESI) m / z : 322 [M+H] + ;HRMS (ESI) m / z calculated for C 20 H 19 NO3+H + 322.1438, found: 322.1434. 5. Compound 3aq: ( E )-5-benzylidene-1-(4-(trifluoromethyl)phenethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded when the amine nucleophile was 4-trifluoromethylphenylethylamine. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 36.1 mg with a 52% yield. When AgOTf was used as the catalyst, the product yielded 46.5 mg with a 67% yield. The melting point was 126-127°C.

[0052] Compound 3aq was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.58 (d, J = 8.1Hz, 2H), 7.38 (d, J = 8.0 Hz, 2H), 7.36-7.31 (m, 2H), 7.23 (d, J = 7.3 Hz, 2H), 7.20-7.16 (m, 1H), 5.77 (s, 1H), 3.92-3.80 (m, 2H), 3.04-2.95 (m, 4H), 2.57-2.50 (m, 2H). 13 C NMR (150 MHz, CDCl3) δ 175.26, 142.59 (q, J C-F= 7.2 Hz),141.74, 136.61, 129.33, 129.22 (q, J C-F = 38.3 Hz), 128.72, 127.80, 125.82,125.67 (q, J C-F = 3.7 Hz), 124.34 (q, J C-F = 272.0 Hz), 103.01, 41.08, 32.76,29.05, 24.09. LRMS (ESI) m / z : 346 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 18 F3NO+H + 346.1413, found: 346.1411. 6. Compound 3ar: ( E )-5-benzylidene-1-(4-fluorophenethyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 4-fluorophenylethylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 48.4 mg with an 82% yield; when AgOTf was used as the catalyst, the product yielded 46.2 mg with a 78% yield, and a melting point of 90-92°C.

[0053] Compound 3ar was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.37-7.33 (m, 2H), 7.26-7.24 (m, 2H), 7.24-7.20 (m, 2H), 7.20-7.16 (m, 1H), 7.04-6.97 (m,2H), 5.80 (s, 1H), 3.82 (dd, J = 8.6, 7.1 Hz, 2H), 3.00-2.97 (m, 2H), 2.93-2.89(m, 2H), 2.56-2.50 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.34, 161.86 (d, JC-F =244.8 Hz), 141.83, 136.71, 134.10 (d, J C-F = 2.6 Hz), 130.39 (d, J C-F = 7.8 Hz),128.70, 127.78, 125.74, 115.52 (d, J C-F = 21.3 Hz), 102.98, 41.51, 32.03, 29.06,24.09. LRMS (ESI) m / z : 296 [M+H] + ; HRMS (ESI) m / z calculated for C 19 H 18 FNO+H + 296.1445, found: 296.1448. 7. Compound 3as: ( E )-5-benzylidene-1-(2-chlorophenethyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 2-chlorophenylethylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product mass was 55.3 mg with an 89% yield; when the catalyst was AgOTf, the product mass was 53.2 mg with an 85% yield, and the melting point was 86-88°C.

[0054] Compound 3as was characterized and the results were as follows: 1 H NMR (600 MHz, CDCl3) δ 7.38 (dd, J = 7.6,1.4 Hz, 1H), 7.34-7.29 (m, 3H), 7.24-7.18 (m, 4H), 7.18-7.15 (m, 1H), 5.93(s, 1H), 3.88-3.81 (m, 2H), 3.10-3.05 (m, 2H), 3.01-2.96 (m, 2H), 2.58-2.54(m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.34, 141.83, 136.93, 136.34, 134.27,131.37, 129.74, 128.64, 128.42, 127.79, 127.22, 125.61, 103.03, 40.03, 31.02,29.15, 24.09. LRMS (ESI) m / z : 314 ([M+H] + , Cl 37 ), 312 ([M+H] + , Cl 35 ); HRMS (ESI) m / z calculated for C 19 H 18 ClNO+H + 312.1150, found: 312.1148. 8. Compound 3at: ( E )-5-benzylidene-1-(4-chlorophenethyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 4-chlorophenylethylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 54.4 mg with an 87% yield; when AgOTf was used as the catalyst, the product yielded 51.9 mg with an 83% yield, and a melting point of 121-122°C.

[0055] Compound 3at was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.32 (m,2H), 7.30-7.27 (m, 2H), 7.24 (d, J = 7.5 Hz, 2H), 7.21-7.16 (m, 3H), 5.78 (s,1H), 3.87-3.78 (m, 2H), 3.01-2.95 (m, 2H), 2.92-2.89 (m, 2H), 2.58-2.50 (m,2H); 13C NMR (150 MHz, CDCl3) δ 175.28, 141.82, 136.91, 136.70, 132.64, 130.33,128.86, 128.72, 127.80, 125.77, 102.98, 41.31, 32.24, 29.07, 24.11. LRMS(ESI) m / z : 314 ([M+H] + , Cl 37 ), 312 ([M+H] + , Cl 35 ); HRMS (ESI) m / z calculated for C 19 H 18 ClNO+H + 312.1150, found: 312.1149. 9. Compound 3au: ( E )-5-benzylidene-1-(4-bromophenethyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 4-bromophenethylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 57.8 mg with an 81% yield; when AgOTf was used as the catalyst, the product yielded 58.9 mg with an 83% yield, and a melting point of 129-130°C.

[0056] Compound 3au was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.45-7.42 (m,2H), 7.36-7.32 (m, 2H), 7.24 (d, J = 7.6 Hz, 2H), 7.20-7.16 (m, 1H), 7.14 (d, J =8.3 Hz, 2H), 5.77 (s, 1H), 3.84-3.79 (m, 2H), 3.00-2.95 (m, 2H), 2.92-2.86(m, 2H), 2.57-2.50 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.23, 141.78, 137.41,136.66, 131.78, 130.69, 128.69, 127.78, 125.74, 120.67, 102.95, 41.20, 32.28,29.04, 24.07. LRMS (ESI) m / z : 358 ([M+H] + , Br 81 ), 356 ([M+H] + , Br 79 ); HRMS (ESI) m / z calculated for C 19 H 18 BrNO+H + 356.0645, found: 356.0643. 10. Compound 3av: ( E )-1-(2-(1 H -pyrrol-1-yl)ethyl)-5-benzylidenepyrrolidin-2-one, the structural formula is ; When the amine nucleophile is 2-(1 H The reaction was carried out with the addition of 1-pyrrol-1-yl)-1-ethylamine. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product mass was 39.6 mg with a yield of 74%; when the catalyst was AgOTf, the product mass was 41.7 mg with a yield of 78%, and the melting point was 98-99°C.

[0057] Compound 3av was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.33-7.30 (m,2H), 7.20-7.15 (m, 3H), 6.69-6.65 (m, 2H), 6.19-6.15 (m, 2H), 5.51 (s, 1H), 4.13 (t, J = 6.5 Hz, 2H), 3.93 (t, J = 6.5 Hz, 2H), 3.00-2.95 (m, 2H), 2.57-2.53(m, 2H); 13LRMS (ESI) m / z :267 [M+H] + ; HRMS (ESI) m / z calculated for C 17 H 18 N2O+H + 267.1492, found: 267.1495. 11. Compound 3aw: ( E )-5-benzylidene-1-(2-(thiophen-2-yl)ethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded when the amine nucleophile was 2-(thiophen-2-yl)-1-ethylamine. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 39.2 mg with a 69% yield. When AgOTf was used as the catalyst, the product yielded 41.5 mg with a 73% yield, and a melting point of 72-74°C.

[0058] Compound 3aw was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.32 (m,2H), 7.26-7.23 (m, 2H), 7.20-7.14 (m, 2H), 6.97-6.95 (m, 1H), 6.92-6.89 (m,1H), 5.78 (s, 1H), 3.90-3.85 (m, 2H), 3.17-3.14 (m, 2H), 3.02-2.97 (m, 2H),2.58-2.55 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.29, 141.74, 140.53, 136.75,128.66, 127.83, 127.19, 125.71, 125.63, 124.18, 102.97, 41.65, 29.11, 26.92,24.12. LRMS (ESI) m / z : 284 [M+H]+ ; HRMS (ESI) m / z calculated for C 17 H 17 NOS+H + 284.1104, found: 284.1105. 12. Compound 3ax: ( E )-5-benzylidene-1-(2-(thien-3-yl)ethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded when the amine nucleophile was 2-(thiophen-3-yl)-1-ethylamine. The reaction mixture was directly added to silica gel and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 47.0 mg with an 83% yield. When AgOTf was used as the catalyst, the product yielded 49.1 mg with an 87% yield. The melting point was 98-99°C.

[0059] Compound 3ax was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.31 (m,2H), 7.30 (dd, J = 4.9, 3.0 Hz, 1H), 7.26-7.23 (m, 2H), 7.19-7.15 (m, 1H), 7.09-7.05 (m, 1H), 7.03 (d, J = 4.9 Hz, 1H), 5.79 (s, 1H), 3.88-3.84 (m, 2H), 3.00-2.95 (m, 4H), 2.57-2.53 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.28,141.89, 138.66, 136.81, 128.67, 128.35, 127.80, 125.96, 125.68, 121.66,102.92, 40.75, 29.12, 27.32, 24.12. LRMS (ESI) m / z : 284 [M+H] + ; HRMS (ESI) m / z calculated for C 17 H 17 NOS+H +284.1104, found: 284.1105. 13. Compound 3ay: ( E )-5-benzylidene-1-(2-methoxybenzyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 2-methoxybenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a light yellow oil. When AuPPh3OTf was used as the catalyst, the product mass was 46.2 mg with a yield of 79%; when AgOTf was used as the catalyst, the product mass was 43.0 mg with a yield of 73%.

[0060] Compound 3ay was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.30-7.26 (m,2H), 7.25-7.21 (m, 1H), 7.16 (d, J = 7.9 Hz, 2H), 7.13-7.09 (m, 1H), 7.06 (d, J =7.6 Hz, 1H), 6.91-6.87 (m, 2H), 5.79 (s, 1H), 4.85 (s, 2H), 3.92 (s, 3H), 3.08-3.03 (m, 2H), 2.72-2.67 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.80,156.94, 141.70, 137.00, 128.54, 128.49, 127.73, 127.59, 125.47, 123.84,120.80, 110.33, 103.90, 55.49, 38.55, 29.33, 24.04. LRMS (ESI) m / z : 294 [M+H] + ;HRMS (ESI) m / z calculated for C 19 H 19 NO2+H + 294.1489, found: 294.1487. 14. Compound 3az: ( E )-5-benzylidene-1-(4-methoxybenzyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 4-methoxybenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product mass was 50.2 mg with an 86% yield; when the catalyst was AgOTf, the product mass was 49.2 mg with an 84% yield, and the melting point was 124-126°C.

[0061] Compound 3az was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.30-7.27 (m,2H), 7.25-7.21 (m, 2H), 7.19-7.16 (m, 2H), 7.15-7.09 (m, 1H), 6.89-6.82 (m,2H), 5.79 (s, 1H), 4.76 (s, 2H), 3.78 (s, 3H), 3.04-3.00 (m, 2H), 2.68-2.63(m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.67, 159.03, 141.74, 136.76, 128.71,128.56, 128.18, 127.75, 125.60, 114.17, 104.06, 55.38, 43.50, 29.18, 24.06.LRMS (ESI) m / z : 294 [M+H] + ; HRMS (ESI) m / z calculated for C 19 H 19 NO2+H + 294.1489,found: 294.1491. 15. Compound 3ba: ( E )-1-benzyl-5-benzylidenepyrrolidin-2-one, the structural formula is ; When the amine nucleophile was benzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product was 44.1 mg with an 84% yield; when the catalyst was AgOTf, the product was 39.8 mg with a 76% yield, and the melting point was 108-109°C.

[0062] Compound 3ba was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.30 (m,2H), 7.30-7.26 (m, 4H), 7.26 (s, 1H), 7.16 (d, J = 7.7 Hz, 2H), 7.14-7.10 (m,1H), 5.76 (s, 1H), 4.83 (s, 2H), 3.08-3.00 (m, 2H), 2.74-2.63 (m, 2H); 13 C NMR(150 MHz, CDCl3) δ 175.70, 141.69, 136.71, 136.04, 128.82, 128.57, 127.76,127.57, 127.27, 125.64, 104.17, 44.08, 29.18, 24.07. LRMS (ESI) m / z : 264 [M+H] + ;HRMS (ESI) m / z calculated for C 18 H 17 NO+H + 264.1383, found: 264.1385. 16. Compound 3bb: (E)-5-benzylidene-1-(3-chloro-4-fluorobenzyl)pyrrolidin-2-one, structural formula: ; When the amine nucleophile was 3-chloro-4-fluorobenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a yellow oil. When AuPPh3OTf was used as the catalyst, the product mass was 48.6 mg with a yield of 77%; when AgOTf was used as the catalyst, the product mass was 44.9 mg with a yield of 71%.

[0063] Compound 3bb was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.34-7.27 (m,3H), 7.19-7.13 (m, 4H), 7.12-7.08 (m, 1H), 5.70 (s, 1H), 4.76 (s, 2H), 3.08-3.03 (m, 2H), 2.71-2.66 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.70, 157.58 (d, J C-F = 248.7 Hz), 141.32, 136.32, 133.12 (d, J C-F = 3.3 Hz), 131.44, 129.44,128.66, 127.79, 127.08 (d, J C-F = 7.2 Hz), 125.90, 116.93 (d, J C-F = 21.4 Hz),104.18, 43.00, 29.08, 24.06; LRMS (ESI) m / z : 318 ([M+H] + , Cl 37 ), 316 ([M+H] + ,Cl 35 ); HRMS (ESI) m / z calculated for C 18 H 15 ClFNO+H + 316.0899, found: 316.0896. 17. Compound 3bc: (E)-5-benzylidene-1-(4-fluorobenzyl)pyrrolidin-2-one, structural formula: ; When the amine nucleophile was 3-fluorobenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product mass was 40.5 mg with a yield of 72%; when the catalyst was AgOTf, the product mass was 46.8 mg with a yield of 83% and a melting point of 108-110°C.

[0064] Compound 3bc was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.32-7.27 (m,3H), 7.18-7.12 (m, 3H), 7.06 (d, J= 7.8 Hz, 1H), 6.99-6.93 (m, 2H), 5.71 (s,1H), 4.82 (s, 2H), 3.08-3.04 (m, 2H), 2.72-2.68 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.67, 163.22 (d, J C-F = 246.5 Hz), 141.45, 138.60 (d, J C-F = 7.2 Hz),136.49, 130.39 (d, J C-F = 8.3 Hz), 128.62, 127.78, 125.79, 122.81 (d, J C-F = 2.9Hz), 114.60 (d, J C-F = 21.2 Hz), 114.12 (d, J C-F = 22.0 Hz), 104.22, 43.61, 29.12,24.05. LRMS (ESI) m / z : 282 [M+H] + ; HRMS (ESI) m / z calculated for C 18 H 16 FNO+H + 282.1289, found: 282.1291. 18. Compound 3bd: (E)-5-benzylidene-1-(4-bromobenzyl)pyrrolidin-2-one, structural formula: ; When the amine nucleophile was 4-bromobenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When AuPPh3OTf was used as the catalyst, the product yielded 43.6 mg with a 64% yield; when AgOTf was used as the catalyst, the product yielded 41.3 mg with a 60% yield, and a melting point of 146-148°C.

[0065] Compound 3bd was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.45 (d, J= 8.3Hz, 2H), 7.31-7.27 (m, 2H), 7.19-7.11 (m, 5H), 5.70 (s, 1H), 4.77 (s, 2H), 3.07-3.02 (m, 2H), 2.70-2.66 (m, 2H); 13 C NMR (150 MHz, CDCl3) δ 175.67,141.44, 136.44, 135.09, 131.96, 129.03, 128.62, 127.77, 125.81, 121.49,104.20, 43.50, 29.12, 24.06. LRMS (ESI) m / z : 344 ([M+H] + , Br 81 ), 342 ([M+H] + ,Br 79 ); HRMS (ESI) m / z calculated for C 18 H 16 BrNO+H + 342.0488, found: 342.0490. 19. Compound 3be: ( E )-4-((2-benzylidene-5-oxopyrrolidin-1-yl)methyl)benzonitrile, the structural formula is ; When the amine nucleophile was 4-cyanobenzylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a light yellow oil. When AuPPh3OTf was used as the catalyst, the product mass was 50.8 mg with an 88% yield; when AgOTf was used as the catalyst, the product mass was 46.5 mg with an 81% yield.

[0066] Compound 3be was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.62 (d, J = 8.3Hz, 2H), 7.38 (d, J = 8.3 Hz, 2H), 7.31-7.27 (m, 2H), 7.17-7.12 (m, 3H), 5.63(s, 1H), 4.87 (s, 2H), 3.12-3.03 (m, 2H), 2.73-2.67 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.65, 141.46, 141.16, 136.10, 132.68, 128.64, 127.81, 127.72,125.96, 118.69, 111.56, 104.24, 43.68, 29.01, 24.03. LRMS (ESI) m / z : 289 [M+H] + ;HRMS (ESI) m / z calculated for C 19 H 16 N2O+H + 289.1335, found: 289.1336. 20. Compound 3bf: ( E )-5-benzylidene-1-(naphthalen-1-ylmethyl)pyrrolidin-2-one, the structural formula is ; The reaction proceeded with 1-naphthylmethylamine as the amine nucleophile. The reaction mixture was directly added to silica gel for mixing and then purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a yellow oil. When AuPPh3OTf was used as the catalyst, the product yielded 34.2 mg with a 55% yield. When AgOTf was used as the catalyst, the product yielded 50.2 mg with an 80% yield.

[0067] Compound 3bf was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 8.12 (d, J = 8.4Hz, 1H), 7.91 (d, J = 8.1 Hz, 1H), 7.79 (d, J = 8.2 Hz, 1H), 7.63-7.58 (m, 1H), 7.57-7.53 (m, 1H), 7.43-7.39 (m, 1H), 7.27 (s, 1H), 7.25 (s, 1H), 7.21 (d, J =7.1 Hz, 1H), 7.15-7.09 (m, 3H), 5.71 (s, 1H), 5.33 (s, 2H), 3.16-3.08 (m, 2H), 2.81-2.73 (m, 2H); 13C NMR (150 MHz, CDCl3) δ 175.71, 141.80, 136.58,133.91, 131.01, 130.24, 129.07, 128.52, 128.06, 127.72, 126.50, 125.95,125.63, 125.45, 123.62, 122.80, 104.55, 42.10, 29.29, 24.10. LRMS (ESI) m / z :314 [M+H] + ; HRMS (ESI) m / z calculated for C 22 H 19 NO+H + 314.1539, found: 314.1541. 21. Compound 3bg: ( E )-5-benzylidene-1-(2,3-dimethylphenyl)pyrrolidin-2-one, the structural formula is ; When the amine nucleophile was 2,3-dimethylaniline, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a white solid. When the catalyst was AuPPh3OTf, the product mass was 17.9 mg with a yield of 32%; when the catalyst was AgOTf, the product mass was 22.0 mg with a yield of 48% and a melting point of 132-133°C.

[0068] Compound 3bg was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.31-7.27 (m,2H), 7.26-7.22 (m, 2H), 7.17 (d, J = 7.7 Hz, 2H), 7.15-7.11 (m, 1H), 7.04-7.00(m, 1H), 5.32 (s, 1H), 3.25-3.19 (m, 2H), 2.83-2.78 (m, 2H), 2.36 (s, 3H),2.06 (s, 3H); 13C NMR (150 MHz, CDCl3) δ 175.11, 143.53, 138.80, 136.71,134.99, 133.94, 130.77, 128.58, 127.68, 126.90, 126.36, 125.63, 104.77,29.72, 24.65, 20.57, 14.12. LRMS (ESI) m / z : 278 [M+H] + ; HRMS (ESI) m / z calculated for C 19 H 19 NO +H + 278.1539, found: 278.1539. 22. Compound 3bh: ( E )-5-benzylidene-1-propylpyrrolidin-2-one, the structural formula is ; When the amine nucleophile was n-propylamine, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to obtain a light yellow oil. When AuPPh3OTf was used as the catalyst, the product mass was 35.2 mg with an 82% yield; when AgOTf was used as the catalyst, the product mass was 37.1 mg with an 86% yield.

[0069] Compound 3bh was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.35-7.30 (m,2H), 7.26 (s, 1H), 7.25 (s, 1H), 7.18-7.14 (m, 1H), 5.77 (s, 1H), 3.62-3.53(m, 2H), 3.04-2.94 (m, 2H), 2.60-2.55 (m, 2H), 1.70-1.63 (m, 2H), 0.97 (t, J =7.4 Hz, 3H); 13 C NMR (150 MHz, CDCl3) δ 175.53, 142.25, 136.98, 128.65, 127.75,125.56, 102.74, 41.82, 29.18, 24.10, 20.05, 11.59. LRMS (ESI) m / z : 216 [M+H]+ ;HRMS (ESI) m / z calculated for C 14 H 17 NO +H + 216.1383, found: 216.1385. 23. Compound 3bi: ( E )-5-benzylidene-1-prop-2-ynylpyrrolidin-2-one, the structural formula is ; When propargylamine was used as the amine nucleophile, the reaction mixture was directly added to silica gel for mixing and purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 1:1, v:v) to yield a colorless oil. When AuPPh3OTf was used as the catalyst, the product yield was 18.3 mg with a yield of 43%; when AgOTf was used as the catalyst, the product yield was 20.0 mg with a yield of 47%.

[0070] Compound 3bi was characterized and the results were: 1 H NMR (600 MHz, CDCl3) δ 7.36-7.32 (m,2H), 7.30-7.28 (m,2H), 7.20-7.16 (m, 1H), 5.99 (s, 1H), 4.41 (d, J = 2.6 Hz,2H), 3.07-3.01 (m, 2H), 2.64-2.58 (m, 2H), 2.23 (t, J = 2.7 Hz, 1H); 13 C NMR (150MHz, CDCl3) δ 174.52, 140.52, 136.56, 128.67, 127.89, 125.87, 104.28, 71.95,29.70, 29.07, 23.89, 0.14; LRMS (ESI) m / z : 212 [M+H] + ; HRMS (ESI) m / z calculated for C 14 H 13 NO +H + 212.1070, found: 212.1071. The above results indicate that the tandem cyclization reaction between alkyne acids and amine nucleophiles disclosed in the present invention has a wide range of applicability of amine nucleophile substrates, good regioselectivity, excellent yield, good functional group tolerance, economical reaction steps, and high bonding efficiency, and can efficiently synthesize 5-alkylmethylenepyrrolidin-2-one compounds.

[0071] Experimental Example 5: Gram-scale amplification reaction experiment A gram-scale scale-up experiment was performed using the following reaction: 1aa (5-phenylpent-4-ynoic acid, 6 mmol) and 2ad (3,4-methylenedioxyphenylethylamine, 9 mmol) in acetonitrile at 100°C for 8 h. The reaction equation is shown below: , When Au(PPh3)OTf was used as the catalyst, the yield of the 5-alkylene-2-pyrrolidone compound (3ap) was 67%; when AgOTf was used as the catalyst, the yield of the 5-alkylene-2-pyrrolidone compound (3ap) was 71%. These results demonstrate the practicality of the method of the present invention.

[0072] Experimental Example 6 The product 5-alkylene-2-pyrrolidone compound (3ap) obtained in Experimental Example 3 was subjected to double bond reduction under Pd-C hydrogen conditions to obtain compound 3ap' (1-(2-(benzodioxolan-5-yl)ethyl)-5-phenylmethylpyrrolidone-2-one); and the ring was closed under TFA activation to obtain the cyclized product 3ap'' (11a-benzyl-6,10,11,11a-tetrahydro-[1,3]dioxa[4,5- h ]pyrrole[2,1- a ]isoquinolin-9(7H)-one). The reaction equation is shown below: , 1. Compound 3ap' was prepared as follows: 5-alkylidene-2-pyrrolidone (3ap, 0.2 mmol, 64 mg) was dissolved in 4 mL of anhydrous methanol, followed by the addition of a 10% Pd / C catalyst (wetted with approximately 55% water). A hydrogen balloon was added, the air was replaced, and the reaction was allowed to proceed at room temperature for 12 h. After completion of the reaction, a triangular funnel was filled with diatomaceous earth, the reaction solution was filtered, evaporated to dryness, and directly added to silica gel for mixing. The sample was purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 2:1, v:v) to obtain a colorless oil (76.2 mg, 94% yield).

[0073] Compound 3ap' was characterized and the results were: 1H NMR (500 MHz, CDCl3) δ 7.31-7.24 (m,2H), 7.25-7.18 (m, 1H), 7.13-7.01 (m, 2H), 6.71 (d, J = 7.9 Hz, 1H), 6.65 (d, J =1.7 Hz, 1H), 6.61 (dd, J = 7.9, 1.7 Hz, 1H), 5.90 (s, 2H), 3.89 (ddd, J = 14.2,8.5, 5.9 Hz, 1H), 3.69-3.53 (m, 1H), 3.14-3.00 (m, 1H), 2.91 (dd, J = 13.5, 4.5Hz, 1H), 2.78 (ddd, J = 13.4, 8.5, 6.7 Hz, 1H), 2.70 (ddd, J = 13.7, 8.2, 5.9 Hz,1H), 2.53 (dd, J = 13.5, 8.2 Hz, 1H), 2.23-2.03 (m, 2H), 1.95-1.79 (m, 1H),1.73-1.60 (m, 1H); 13 C NMR (125 MHz, CDCl3) δ 175.21, 147.81, 146.25, 137.12,132.82, 129.28, 128.75, 126.87, 121.72, 109.20, 108.41, 100.98, 59.20, 42.50,39.59, 33.83, 29.88, 24.02. LRMS (ESI) m / z : 324 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 21 NO3+H + 324.1594, found: 324.1594. 2. The preparation steps of compound 3ap'' are as follows: 5-alkylidene-2-pyrrolidone compound (3ap, 0.2 mmol, 64 mg) was dissolved in 4 mL of anhydrous dichloromethane, and then trifluoroacetic acid (0.2 mmol) was added. The mixture was covered and refluxed at 50°C for 12 h. After the reaction was completed, 15 mL of sodium carbonate solution was added for neutralization, and then 10 mL of dichloromethane was added. After extraction three times, the organic layers were combined, the solvent was evaporated under reduced pressure, and silica gel was added for sample preparation. The product was purified by flash chromatography on silica gel (petroleum:ethyl acetate = 4:1 → petroleum:ethyl acetate = 2:1, v:v) to obtain a colorless oil (72.8 mg, 91% yield).

[0074] Compound 3ap'' was characterized and the results were: 1 H NMR (400 MHz, CDCl3) δ 7.35-7.21 (m,3H), 7.15-7.03 (m, 2H), 6.74-6.61 (m, 1H), 6.59-6.50 (m, 1H), 5.95 (dt, J =9.1, 1.1 Hz, 2H), 4.31 (ddd, J = 13.0, 6.7, 1.7 Hz, 1H), 3.20 (d, J = 13.8Hz, 1H), 3.14-2.98 (m, 1H), 2.95 -2.77 (m, 2H), 2.65 (ddd, J = 16.1, 4.9, 1.7Hz, 1H), 2.54-2.39 (m, 1H), 2.14-1.89 (m, 2H), 1.55-1.33 (m, 1H); 13 C NMR (101MHz, CDCl3) δ 173.57, 146.73, 146.55, 136.16, 135.53, 130.21, 128.61, 127.27,126.06, 108.73, 105.44, 101.19, 64.69, 46.52, 34.43, 32.72, 30.84, 28.64.LRMS (ESI) m / z : 322 [M+H] + ; HRMS (ESI) m / z calculated for C 20 H 20 NO3+H + 322.1438,found: 322.1440. The above results further prove that the 5-alkylmethylenepyrrolidin-2-one compound synthesized in the present invention can be applied to the structural modification of alkaloids, is an important type of synthetic building block, and has broad application prospects.

Claims

1. A 5-alkylene-2-pyrrolidone compound, characterized in that The general structural formula of the 5-alkylene-2-pyrrolidone compound is: ； Among them, R 1 is benzyl, phenethyl, arylethyl, 1-naphthylmethyl, phenyl, alkyl or propargyl; R 2 is hydrogen, halogen, alkyl, alkoxy, nitro, cyano or trifluoromethyl.

2. The 5-alkylene-2-pyrrolidone compound according to claim 1, characterized in that The structural formula of the 5-alkylene-2-pyrrolidone compound is:

3. The method for preparing the 5-alkylene-2-pyrrolidone compound according to claim 1 or 2, characterized in that: The method comprises the following steps: dissolving an acetylenic acid, an amine nucleophile and a catalyst in an organic solvent at a molar ratio of 0.5-1.5:1-2:0.01-0.1, and then reacting at 90-120° C. for 7-10 hours to obtain a 5-alkylene-2-pyrrolidone compound; The structural formula of the acetylenic acid is , the structural formula of the amine nucleophile is ; where R 1 is benzyl, phenethyl, arylethyl, 1-naphthylmethyl, phenyl, alkyl or propargyl; R 2 is hydrogen, halogen, alkyl, alkoxy, nitro, cyano or trifluoromethyl.

4. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 3, wherein: The molar ratio of the alkyne acid, the amine nucleophile and the catalyst is 1:1.5:0.

05.

5. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 3, wherein: The acetyloic acid is 5-phenylpent-4-acetyloic acid, 5-(4-methoxyphenyl)-4-acetyloic acid, 5-(3-methylphenyl)-4-acetyloic acid, 5-(4-methylphenyl)-4-acetyloic acid, 5-(2-fluorophenyl)-4-acetyloic acid, 5-(4-fluorophenyl)-4-acetyloic acid, 5-(3-chlorophenyl)-4-acetyloic acid, 5-(4-nitrophenyl)-4-acetyloic acid, 5-(4-cyanophenyl)-4-acetyloic acid, 5-(4-chlorophenyl)-4-acetyloic acid, 5-(4-nitrophenyl)-4-acetyloic acid, 5-(4-cyanophenyl)-4-acetyloic acid, 5-(2-fluorophenyl)-4-acetyloic acid, 5-(4-fluorophenyl)-4-acetyloic acid, 5-(3-chlorophenyl)-4-acetyloic acid, 5-(4-nitrophenyl)-4-acetyloic acid, 5-(4-cyanophenyl)-4-acetyloic acid, 5-(4-cyanophenyl)-4-acetyloic acid, 5-(4-chlorophenyl)-4-acetyloic acid, 5-(4-chlorophenyl)-4-acetyloic acid, 5-(4- )-4-pentynoic acid, 5-(4-trifluoromethylphenyl)-4-pentynoic acid or 5-(thiophen-2-yl)-4-pentynoic acid; the amine nucleophile is 2-phenylethylamine, 3,4-dimethoxyphenylethylamine, 2-methoxyphenylethylamine, 3-methoxyphenylethylamine, 3,4-methylenedioxyphenylethylamine, 4-trifluoromethylphenylethylamine, 4-fluorophenylethylamine, 2-chlorophenylethylamine, 4-chlorophenylethylamine, 4-bromophenylethylamine, 2-(1 H 1-pyrrol-1-yl)-1-ethylamine, 2-(thiophen-2-yl)-1-ethylamine, 2-(thiophen-3-yl)-1-ethylamine, 2-methoxybenzylamine, 4-methoxybenzylamine, benzylamine, 3-chloro-4-fluorobenzylamine, 3-fluorobenzylamine, 4-bromobenzylamine, 4-cyanobenzylamine, 1-naphthylmethylamine, 2,3-dimethylaniline, n-propylamine, or propargylamine.

6. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 3, wherein: The catalyst is AgNO3, Ag2CO3, AgOAc, AgOTf, Pd(OAc)2, PdCl2(PPh3)2, Cu(OAc)2, CuCl2, CuI, Zn(OAc)2, [RuCl2( p-cym )]2, Mn(OAc)2, Co(OAc)2, Co(acac)2, NiCl2, Ni(OTf)2, Au(PPh3)Cl or Au(PPh3)OTf.

7. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 6, wherein: The catalyst is AgOTf or Au(PPh3)OTf.

8. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 3, wherein: The organic solvent is acetonitrile, toluene, 1,2-dichloroethane, 1,4-dioxane, ethanol or dimethyl sulfoxide.

9. The method for preparing a 5-alkylene-2-pyrrolidone compound according to claim 8, wherein: The organic solvent is acetonitrile.

10. Use of the 5-alkylene-2-pyrrolidone compound according to claim 1 or 2 in the preparation of antibacterial drugs.

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