Chloro pyrrolo [4, 3, 2-de] quinoline alkaloid as well as preparation method and application thereof

Abstract

The invention relates to chloropyrrolo [4, 3, 2-de] quinoline alkaloids as well as a preparation method and application thereof. The structural formula of the quinoline alkaloid is shown in the specification. The obtained chloro-pyrrolo [4, 3, 2-de] quinoline alkaloids I-1-I-20 have anti-plant virus activity, and especially can inhibit tobacco mosaic virus and potato Y virus. The invention develops an efficient synthesis method of the pyrrolo [4, 3, 2-de] quinoline derivative, and lays a foundation for biological activity research of the pyrrolo [4, 3, 2-de] quinoline compound. # imgabs0 #

Description

Technical Field

[0001] The invention relates to chloropyrrolo[4,3,2-de]quinoline alkaloids and a preparation method and application thereof, belonging to the technical field of agricultural protection. Background Art

[0002] Among crop diseases and insect pests, plant viral diseases are one of the important issues facing agricultural development and plant protection. They are known as "plant cancer". The plant viruses that cause serious damage mainly include tobacco mosaic virus (TMV), cucumber mosaic virus (CMV), potato virus Y (PVY), etc. After being infected by them, crops are seriously affected in yield and quality, often causing huge economic losses. The unique extreme environment of the ocean, such as high salt, high pressure, and low temperature, forces marine organisms to form some marine natural products (MNPs) with unique structures and significant biological activities. These natural products have some special skeletons that can interact with biological macromolecules, providing advantages for their development into new drugs (Life Sci. Technol., 2021, 3, 44–61.).

[0003] Pyrrolo[4,3,2-de]quinoline alkaloids are secondary metabolites extracted from toads and marine organisms and are a class of natural products with drug potential. Since Wieland et al. first isolated bufothionine, an alkaloid with a pyrrolo[4,3,2-de]quinoline nucleus, from the skin secretions of the South American toad Bufo arenarum in 1930, more than 100 natural products with similar nucleus structures have been isolated and named, including dehyrobufotenine, ammosamide, damirone, batzelline, etc. (see structural formula 1), most of which are secondary metabolites of marine organisms [Qi Chenxiao, et al. Drug Progress, 2015, 39(1), 23–31.]. Most pyrrolo[4,3,2-de]quinoline natural products have good biological activities, including antiparasitic, antiviral, and antitumor activities (Davis RA, et al. J. Med. Chem. 2012, 55(12), 5851–5858; Hu JF, et al. J. Nat. Prod. 2002, 65(4), 476–480; Oshiyama T, et al. Tetrahedron 2012, 68(46), 9376–9383; Chang LC, et al. J. Nat. Prod. 2002, 65(5), 776–778.).

[0004]

[0005] Structural formula of the chemical structure of pyrrolo[4,3,2-de]quinoline alkaloids

[0006] In the ammosamide series, except for ammosamide FP, which is a product of artificial fermentation using marine actinomycetes, other compounds are extracted from marine microorganisms. Ammosamide AC is isolated from marine Streptomyces CNR-698, and ammosamdie E is isolated from marine actinomycetes Streptomyces variabilis SNA-020 (Pan E, et al. Chem. Sci. 2013, 4 (1), 482-488; Hughes CC, et al. J. Am. Chem. Soc. 2010, 132 (8), 2528-2529.). In 2009, the Fenical research group isolated ammosamide A and ammosamide B from the marine chain fungus CNR-698 [Hughes CC, et al. Angew. Chem. Int. Ed. 2009, 48, 725–727.] and found that they showed effective cytotoxicity against HCT-116 colon cancer in the in vitro antitumor activity test. 50 All were 320 nM; and in different cancer cell lines, they showed higher selectivity, ranging from 20 nM to 1 μM.

[0007] Since the Fenical research group completed the first synthesis of ammosamide B with a total yield of 2.7% in 17 steps [Hughes CC, et al. J. Am. Chem. Soc. 2010, 132 (8), 2528–2529.], many research teams have reported on its synthesis. Commonly used synthesis strategies can be summarized into two categories:

[0008] ① Using indigo carmine derivatives as raw materials, the pyridine ring is constructed through the key steps of Witting reaction and intramolecular cyclization reaction, and the target compound is obtained through further transformation. The research group of Professor He Zhengjie of Nankai University used the developed cyclization reaction of 3-acylmethylindolinone and Huisgen salt as the key step, and used indole derivatives as the starting materials. After 4 steps, 43% of the total yield was achieved to achieve the efficient synthesis of ammosamide B (see structural formula 2) [Yang CJ, et al. Org. Lett. 2016, 18, 1486–1489.]; the only drawback of the route is that the starting material needs to be converted from 4-chloroindigo carmine through N-methylation reaction (yield 84%) and Witting reaction (yield 35%) to obtain it.

[0009]

[0010] Structural formula 2: Ammosamide B is synthesized using indigo carmine and its derivatives as raw materials

[0011] ② Using m-dinitrobenzene derivatives as raw materials, the key step Doebner-von Miller reaction is used to achieve the construction of pyrrolo[4,3,2-de]quinoline structure, and then further transformed to obtain the target compound [Wu Q, et al. Tetrahedron Lett. 2010, 51, 4806–4807; Reddy PV, et al. J. Med. Chem. 2012, 55, 367–377.]. As shown in structural formula 3, using compound 1,3-dichloro-4,6-dinitrobenzene as the starting material, the synthesis of alkaloid ammosamide B can be achieved with a total yield of 6.9% after 9 steps.

[0012]

[0013] The structure of ammosamide B was synthesized from three dinitrobenzene derivatives as raw materials.

[0014] So far, although the alkaloid ammosamides have been found to have a variety of biological activities, the application of this compound in anti-plant virus has not been found so far, and the application of this type of compound is limited due to its complex synthesis route and high cost. Summary of the invention

[0015] In view of the shortcomings of the prior art, the present invention provides chloropyrrolo[4,3,2-de]quinoline alkaloids and preparation methods and uses thereof. The chloropyrrolo[4,3,2-de]quinoline alkaloids of the present invention have good anti-plant virus activity.

[0016] The chloropyrrolo[4,3,2-de]quinoline alkaloids I of the present invention are compounds shown in the following I-1 to I-20:

[0017]

[0018] The preparation method of the chloropyrrolo[4,3,2-de]quinoline alkaloid I in claim 1 is the following I-1 to I-20:

[0019] Synthesis of compound I-1: prepared according to the method shown in equation 1, firstly, using DMF as solvent, 6-chloroindigo carmine reacts with MeI under the action of K2CO3 to undergo N-methylation reaction to obtain 1-methyl-6-chloroindigo carmine; then, in the presence of acetic acid, 1-methyl-6-chloroindigo carmine and ethyl 2-oxo-3-(triphenylphosphine) propionate are heated to 75°C in tetrahydrofuran solvent for reaction for 12 hours to obtain compound E-1-methyl-3-(ethyl 2-oxopropionate-1-enyl)-2-oxo-6-chloroindole; subsequently, di-tert-butyl azodicarboxylate and triphenylphosphine are reacted at room temperature for 5 hours under N2 protection conditions, and then a mixed solution of anhydrous ethanol and H2SO4 (2.5M) is reacted at 60°C for 1 hour to obtain compound I-1;

[0020]

[0021] Synthesis of compounds I-2 to I-4: Prepared according to the method of formula 2, firstly, compound I-1 is hydrolyzed in a tetrahydrofuran-water mixed solution of sodium hydroxide, and after adjusting to acidity with hydrochloric acid, compound I-2 containing a carboxylic acid group can be obtained; subsequently, compound I-3 is obtained by amidation reaction with n-butylamine under the action of O-benzotriazole-tetramethyluronium hexafluorophosphate (HBTU) and N,N-diisopropylethylamine (DIPEA); oxalyl chloride is added dropwise to acetonitrile in which triphenylphosphine is dissolved, and then a mixed solution of acetonitrile containing compound I-2 and aniline is added to obtain compound I-4;

[0022]

[0023] Synthesis of compounds I-5 to I-6: Prepared according to the method of equation 3, firstly, compound I-1 is treated with ammonia water at 60°C for 6 hours to obtain compound I-5, which also contains a small amount of I-6; compound I-5 is stirred in a methanol mixed solution containing a small amount of concentrated hydrochloric acid for 1 hour to obtain compound I-6;

[0024]

[0025] Synthesis of compounds I-7 to I-12: Prepared according to the method of formula 4, compound I-1 is stirred in a mixed solution of hydrazine hydrate and methanol for 1 hour to achieve the preparation of compound I-7; compound I-7 is then treated with a methanol solution containing concentrated hydrochloric acid to obtain compound I-8; hydrazide compound I-8 and different substituted aldehyde compounds are refluxed in a methanol solvent for 2-6 hours to obtain compounds I-9 to I-12;

[0026]

[0027] Synthesis of compounds I-13 to I-15: Prepared according to the method of formula 5, firstly, compound I-1 is treated in a sulfuric acid-nitric acid mixture, and reacted at 0°C for 3 hours to obtain a mononitration product 1-methyl-4-ethylformate-6-nitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline, and reacted at 0°C slowly to 35°C for 4 hours to obtain a dinitration product 1-methyl-4-ethylformate-6,8-dinitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline. -7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline; the nitration product can be reduced by iron powder to achieve the synthesis of 1-methyl-4-ethylformate-6-amino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-13) and 1-methyl-4-ethylformate-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline; and then treated with ammonia water to obtain compounds I-14 and I-15;

[0028]

[0029] Synthesis of compounds I-16 to I-17: Prepared according to the method of equation 6, using potassium carbonate as a base and DMF as a solvent, compound I-13 reacts with methyl iodide to obtain compound I-16, and reacts with benzyl bromide to obtain compound I-17;

[0030]

[0031] Synthesis of compounds I-18 to I-20: Prepared according to the method of equation 7, compound I-13 is reacted with acetic anhydride in acetic acid at 120°C for 4 hours to obtain compound I-18; under ice bath conditions, with triethylamine as an acid-binding agent, compound I-13 is reacted with benzoyl chloride to obtain compounds I-19 and I-20;

[0032]

[0033] The chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 of the present invention are used as anti-plant virus agents, wherein the plant virus is tobacco mosaic virus, pepper virus, rice virus, tomato virus, sweet potato virus, potato virus Y, cucurbit virus or corn dwarf mosaic virus. Among them, they exhibit excellent anti-tobacco mosaic virus activity, and most of the compounds have significantly better activity than the commercial variety ribavirin, and most of the compounds have significantly better anti-plant virus activity than the natural product ammosamide B. DETAILED DESCRIPTION

[0034] Example 1 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-1)

[0035] The preparation method is as follows:

[0036] In the first step, 6-chloroindigo red (1.0 g, 5.13 mmol) was dissolved in 15 mL of DMF. K2CO3 (0.84 g, 6.08 mol, 1.2 equiv) was added at room temperature and stirred for 10 min. MeI (0.86 g, 6.08 mol, 1.2 equiv) was added and the reaction was continued for 12 h. After the reaction was completed as determined by TLC, 150 mL of water was added and the mixture was extracted three times with 20 mL of ethyl acetate respectively. The organic layer was collected, dried over anhydrous sodium sulfate, and concentrated in vacuo to obtain 0.95 g of orange-red solid 1-methyl-6-chloroindigo red with a melting point of 165-166 ° C and a yield of 93%. 1 HNMR (400MHz, CDCl3) δ7.54 (d, J=7.9Hz, 1H, Ar-H), 7.11 (d, J=7.9Hz, 1H, Ar-H), 6.92 (s, 1H, Ar-H), 3.26 (s, 3H, N-CH3). 13 C NMR (100MHz, CDCl3) δ181.8,158.2,152.5,144.9,126.3,124.0,115.8,110.8,26.4.

[0037] In the second step, 1-methyl-6-chloroindigo carmine (1.0 g, 5.13 mmol) and ethyl 2-oxo-3-(triphenylphosphine) propionate (3.85 g, 10.26 mmol, 2 equiv) were dissolved in 38 mL of THF, and acetic acid (3.1 g, 51.3 mmol, 10 equiv) was added dropwise. Under N2 protection, the reaction was carried out at 75°C for 12 h, and the solvent was concentrated in vacuo and purified by column chromatography (petroleum ether / ethyl acetate / dichloromethane = 5 / 1 / 1) to obtain a crude product. After vacuum concentration and solvent removal, the crude product was recrystallized from (petroleum ether / ethyl acetate = 4 / 1) to obtain 0.71 g of a red-brown solid E-1-methyl-3-(2-oxopropionic acid ethyl-1-enyl)-2-oxo-6-chloroindole, with a melting point of 158-166°C and a yield of 65%. 1 H NMR (400MHz, CDCl3) δ8.62(d,J=8.3Hz,1H,Ar-H),7.83(s,1H,CH),7.03(d,J=8.3Hz,1H,Ar-H),6. 79(s,1H,Ar-H),4.42(q,J=5.8Hz,2H,OCH2),3.23(s,3H,N-CH3),1.43(t,J=5.8Hz,3H,OCH2-CH3). 13C NMR (100MHz, CDCl3) δ182.9,167.5,160.9,148.3,140.5,139.2,130.0,123.0,121.8,118.5,109.2,63.1,26.5,14.1.

[0038] In the third step, E-1-methyl-3-(2-oxopropionic acid ethyl-1-enyl)-2-oxo-6-chloroindole (0.4 g, 1.36 mmol), di-tert-butyl azodicarboxylate (DTBAD, 0.36 g, 2.04 mmol) and triphenylphosphine (0.54 g, 2.04 mmol) were dissolved in 14 mL THF, reacted at room temperature for 5 h under N2 protection, concentrated and desolvated in vacuo, 28 mL of anhydrous ethanol and 0.112 mL of H2SO4 (2.5 M) solution were added, reacted at 60 ° C for 1 h, concentrated and desolvated in vacuo, and purified by column chromatography (petroleum ether / ethyl acetate = 8 / 1 to 5 / 1) to obtain 0.29 g of yellow solid 1-methyl-4-carboxylic acid ethyl ester-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-1), melting point 183-190 ° C, yield 73%. 1 HNMR (400MHz, CDCl3) δ8.62(s,1H,Ar-H),7.91(d,J=1.0Hz,1H,Ar-H),6.96(d,J=1.0Hz,1H , Ar-H), 4.59 (q, J = 7.1Hz, 2H, OCH2), 3.45 (s, 3H, N-CH3), 1.51 (t, J = 7.1Hz, 3H, OCH2-CH3). 13 C NMR(100MHz, CDCl3)δ166.4,164.4,152.6,145.0,141.4,139.5,135.4,121.5,119.5,118.2,108.6,62.8,26.9,14.3.HRMS(ESI)calcd for C 14 H 12 ClN2O3[M+H] + 291.0531, found 291.0535.

[0039] Example 2 Synthesis of 1-methyl-4-carboxylic acid-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-2)

[0040] Compound I-1 (0.10 g, 0.34 mmol) was dissolved in 5 mL of tetrahydrofuran and 3 mL of water, and sodium hydroxide (0.03 g, 0.64 mmol, 2 equiv) was added. The reaction was carried out at room temperature for 3 h, and hydrochloric acid solution (3 M) was added until no solid was precipitated. The mixture was filtered to obtain 0.081 g of a reddish brown solid with a melting point of 248-254°C and a yield of 90%. 1 H NMR (400MHz, DMSO-d6) δ13.46(s,1H,COOH),7.97(s,1H,Ar-H),7.50(s,1H,Ar-H),6.76(s,1H,Ar-H),2.86(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ166.3,166.1,153.5,144.3,142.1,138.9,135.3,120.4,119.1,117.7,109.3,27.3.HRMS(ESI)calcd for C 12 H6ClN2O3[MH] - 261.0072, found 261.0077.

[0041] Example 3 Synthesis of 1-methyl-4-(N-n-butylformamide)-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-3)

[0042] Compound I-2 (0.05 g, 0.19 mmol), O-benzotriazole-tetramethyluronium hexafluorophosphate (HBTU, 0.07 g, 0.19 mmol, 1.0 equiv), N,N-diisopropylethylamine (DIPEA, 0.10 g, 0.76 mmol, 4.0 equiv) and n-butylamine (0.015 g, 0.21 mmol, 1.1 equiv) were dissolved in 5 mL of DMF, at room temperature overnight, 50 mL of water was added, and the mixture was extracted three times with 10 mL of ethyl acetate respectively, concentrated in vacuo to remove the solvent, and purified by column chromatography (dichloromethane / methanol = 100 / 1) to obtain 0.016 g of an orange solid with a melting point of 133-140°C and a yield of 26%. 1H NMR(400MHz,DMSO-d6)δ9.01(d,J=6.1Hz,1H,NH),8.40(s,1H,Ar-H),7.77(s,1H,Ar-H),7.44(s,1H,Ar-H),3.40–3.3 7(m,2H,N-CH2),3.37(s,3H,N-CH3),1.60–1.55(m,2H,CH2),1.38–1.33(m,2H,CH3-CH2),0.93(t,J=7.3Hz,3H,CH3). 13 C NMR(100MHz,DMSO-d6)δ166.5,163.5,155.4,143.5,142.4,139.1,139.0,135.7,119.8,119.1,115.6,109.0,31.7,27.3,20.1,14.2.HRMS(ESI)calcd forC 16 H 17 ClN3O2[M+H] + 318.1004, found 318.1007.

[0043] Example 4 Synthesis of 1-methyl-4-(N-phenylcarboxamide)-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-4)

[0044] Triphenylphosphine (Ph3P, 0.11 g, 0.38 mmol, 1.0 equiv) was dissolved in 0.2 mL of acetonitrile, and oxalyl chloride (0.06 g, 0.49 mmol, 1.3 equiv) was added dropwise. The reaction was carried out at room temperature for 10 minutes. Compound I-2 (0.10 g, 0.38 mmol) and aniline (0.05 g, 0.49 mmol, 1.3 equiv) were dissolved in 0.3 mL of acetonitrile, mixed evenly, and slowly added dropwise to the former. The reaction was continued at room temperature for 1 hour. 10 mL of water was added, and the mixture was extracted three times with 5 mL of ethyl acetate respectively. The mixture was concentrated in vacuo to remove the solvent, and purified by column chromatography (dichloromethane / petroleum ether = 4 / 1) to obtain 0.03 g of a yellow solid with a melting point of 266-275°C and a yield of 21%. 1 HNMR (400MHz, CDCl3) δ10.08(s,1H,NH),8.86(s,1H,Ar-H),7.86–7.84(m,2H,Ar-H),7.82(s,1H,A r-H),7.44(d,J=6.2Hz,2H,Ar-H),7.28–7.22(m,1H,Ar-H),6.98(s,1H,Ar-H),3.47(s,3H,N-CH3). 13C NMR(100MHz, CDCl3)δ166.4,161.0,154.3,143.6,141.6,139.7,137.4,136.0,129.2,124.6,120.4,119.9,116.3,108.2,29.7.HRMS(ESI)calcd for C 18 H 13 ClN3O2[M+H] + 338.0691, found 338.0694.

[0045] Example 5 Synthesis of 1-methyl-4-formamide-2-imide-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-5)

[0046] Compound I-1 (0.10 g, 0.34 mmol) was dissolved in 7.5 mL of ammonia water (28%) and 7.5 mL of water, reacted at 60°C for 6 hours, concentrated under vacuum to remove solvent, and purified by column chromatography (dichloromethane / methanol = 10 / 1) to obtain 0.07 g of compound I-5, a yellow solid, melting point 237-244°C, yield 78%. 1 H NMR(400MHz,DMSO-d6)δ8.76(s,1H,NH),8.12(s,1H,Ar-H),7.76(s,1H,CONH2) ,7.67(s,1H,CONH2),7.17(s,1H,Ar-H),6.32(s,1H,Ar-H),2.77(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ172.9,166.6,150.5,149.4,149.0,135.9,116.2,114.8,114.2,105.6,103.7,30.6.HRMS(ESI)calcd for C 12 H 10 ClN4O[M+H] + 261.0538, found 261.0536.

[0047] Example 6 Synthesis of 1-methyl-4-formamido-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-6)

[0048] Compound I-5 (0.10 g, 0.38 mmol) was dissolved in 15 mL of methanol, and three drops of concentrated hydrochloric acid were added. The mixture was reacted for one hour at room temperature, and vacuum concentrated to remove the solvent to obtain 0.1 g of a yellow solid with a melting point of 274-282°C and a yield of 20%. 1H NMR (400MHz, DMSO-d6) δ8.36(s,1H,Ar-H),8.31(s,1H,CONH2),7.98(s,1H,CONH2),7.71(s,1H,Ar-H),7.37(s,1H,Ar-H),3.36(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ166.5,165.7,155.5,143.6,142.4,138.9,135.7,120.0,119.2,115.6,109.1,27.3.HRMS(ESI)calcd forC 12 H9ClN3O2[M+H] + 262.0378, found 262.0379.

[0049] Example 7 Synthesis of 1-methyl-4-carboxyhydrazide-2-hydrazino-2-hydroxy-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-7)

[0050] Compound I-1 (0.30 g, 1.0 mmol) was dissolved in 5 mL of hydrazine hydrate and 5 mL of methanol. The mixture was reacted for 2 h at room temperature and filtered to obtain 0.36 g of an orange solid with a melting point of 221-226 °C and a yield of 80%. 1 H NMR(400MHz,DMSO-d6)δ10.22(s,1H,CO-NH),10.08(s,1H,OH),7.76(s,1H,Ar-H),7.38(s,1H,Ar-H),6.63 (s,1H,Ar-H),6.50(d,J=4.2Hz,1H,NH),4.87(s,2H,NH2),4.67(s,2H,NH2),2.84(d,J=4.4Hz,3H,N-CH3). 13 CNMR(100MHz,DMSO-d6)δ169.3,162.4,150.5,150.3,149.2,147.6,141.6,136.9,117.3,116.2,114.3,106.5,40.6,39.3,31.2.HRMS(ESI)calcd for C 12 H 14 ClN6O2[M+H] + 309.0861, found 309.0868.

[0051] Example 8 Synthesis of 1-methyl-4-carboxyhydrazide-2-hydrazino-2-oxo-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-8)

[0052] Compound I-7 (0.10 g, 0.32 mmol) was dissolved in 10 mL of anhydrous methanol, and three drops of concentrated hydrochloric acid were added. The mixture was reacted overnight at room temperature and concentrated in vacuo to obtain 0.9 g of a yellow solid with a melting point of 198-205°C and a yield of 100%. 1 HNMR (400MHz, CD3OD) δ8.60(s,1H,Ar-H),7.86(d,J=1.1Hz,1H,Ar-H),7.32(d,J=1.1Hz,1H,Ar-H),3.47(s,3H,N-CH3). 13 C NMR(100MHz,CD3OD)δ166.4,163.4,151.7,144.0,142.0,140.0,135.9,120.0,115.3,109.0,25.8.HRMS(ESI)calcd for C 12 H 10 ClN4O2[M+H] + 277.0487, found 277.0482.

[0053] Example 9 Synthesis of 1-methyl-4-(Z / E-n-butylformylhydrazone)-2-hydrazino-2-oxo-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-9)

[0054] Compound I-8 (0.10 g, 0.36 mmol) was dissolved in 20 mL of methanol, and n-butyraldehyde (1.08 mmol, 3.0 equiv) was added. The reaction was carried out at 60°C for 2 to 6 hours, and the mixture was concentrated in vacuo to remove the solvent, recrystallized, and filtered to obtain the target product I-9. The product was a yellow solid with a melting point of 144–147°C and a yield of 45%. 1HNMR(400MHz,DMSO-d6)δ12.09and 11.96(s,1H,NHin 2:8ratio due to cis-trans-isomer),8.79and 8.41(s,1H,Ar-H in 2:8ratio due to cis-trans-isomer),8.37and 8.21(s,1H,Ar-H in 2:8ratio due to cis-trans-isomer),7.89and 7.78(s,1H,Ar-H in 2:8ratio due to cis-trans-isomer),5.92and5.87(m,1H,N-CHin 2:8ratio due to cis-trans-isomer),3.99and 3.42(s,3H,N-CH3),2.36–2.30and 2.26–2.19(m,2H,NCH-CH2),1.49–1.42(m,1H,CH3-CH2),1.05–1.02and0.95–0.92(t,J=7.3Hz,3H,CH2-CH3). 13 C NMR(100MHz,DMSO-d6)δ166.5,160.2,154.5,144.7,143.6,142.5,141.1,139.8,139.1,119.8,116.2,109.3,86.9,27.4,22.5,14.3.HRMS(ESI)calcd for C 16 H 16 ClN4O2[M+H] + 331.0956, found 331.0959.

[0055] Example 10 Synthesis of 1-methyl-4-(E-phenylenedihydrazone)-2-hydrazino-2-oxo-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-10)

[0056] Except for using benzaldehyde instead of n-butyraldehyde, the other steps were the same as in Example 9 to obtain yellow solid compound I-10 with a melting point of 175-186°C and a yield of 76%. 1H NMR(400MHz,DMSO-d6)δ12.37(s,1H,NH),8.72(s,1H,Ar-H),8.47(s,1H,Ar-H),8.40(s,1H,Ar-H),7.93–7.8 8(m,2H,Ar-H),7.85–7.81(m,1H,Ar-H),7.77(d,J=6.6Hz,2H,Ar-H),7.53(s,1H,N-CH),3.99(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ161.7,142.0,138.7,132.0,131.4,131.0,128.9,128.3,119.8,117.0,109.2,107.9,106.7,26.9.HRMS(ESI)calcd for C 19 H 14 ClN4O2[M+H] + 365.0800, found 365.0803.

[0057] Example 11 Synthesis of 1-methyl-4-(Z / E-p-methoxyphenylcarbamoylhydrazone)-2-hydrazino-2-oxo-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-11)

[0058] Except for using 4-methoxybenzaldehyde instead of n-butyraldehyde, the other steps were the same as in Example 9 to obtain yellow solid compound I-11 with a melting point of 163-167°C and a yield of 81%. 1 H NMR(400MHz,DMSO-d6)δ12.20(s,1H,NH),8.64(s,1H,Ar-H),8.46(s,1H,Ar-H),7.81(s,1H,Ar-H),7.71(d, J=8.2Hz,2H,Ar-H),7.47(s,1H,N-CH),7.05(d,J=8.2Hz,2H,Ar-H),3.83(s,3H,OCH3),3.39(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ161.6,155.1,150.3,143.6,141.6,139.2,130.4,129.4,127.2,119.9,116.2,114.9,109.3,55.8,27.4.HRMS(ESI)calcd for C 20 H 16 ClN4O3[M+H] + 395.0905, found 395.0909.

[0059] Example 12 Synthesis of 1-methyl-4-(Z / E-p-nitrophenylformylhydrazone)-2-hydrazino-2-oxo-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-12)

[0060] Except for using 4-nitrobenzaldehyde instead of n-butyraldehyde, the other steps were the same as in Example 9 to obtain yellow solid compound I-12 with a melting point of 269-280°C and a yield of 90%. 1 H NMR(400MHz,DMSO-d6)δ12.68(s,1H,NH),8.84(s,1H,Ar-H),8.50(s,1H,Ar-H),8.35(d,J=7.9Hz, 2H, Ar-H), 8.03 (d, J = 7.9Hz, 2H, Ar-H), 7.85 (s, 1H, Ar-H), 7.52 (s, 1H, N-CH), 3.47 (s, 3H, N-CH3). 13 C NMR(100MHz,DMSO-d6)δ155.1,151.6,148.0,140.9,139.3,136.8,136.0,128.7,124.7,119.9,113.2,27.4.HRMS(ESI)calcd forC 19 H 13 ClN5O4[M+H] + 410.0651, found 410.0653.

[0061] Example 13 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-6-amino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-13)

[0062] In the first step, 8 mL of concentrated nitric acid was slowly added dropwise to 8 mL of concentrated sulfuric acid under ice bath conditions, compound I-1 (0.5 g, 1.0 mmol) was added, the reaction was continued for 3 h, 400 mL of water was added, and 20 mL of ethyl acetate was used for extraction three times. The mixture was concentrated and desolvated in vacuo, and purified by column chromatography (petroleum ether / dichloromethane = 3 / 1) to obtain 0.41 g of yellow solid 1-methyl-4-carboxylic acid ethyl ester-6-nitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline, melting point 180-185 ° C, yield 95%. 1 H NMR (400MHz, DMSO-d6) δ8.50(s,1H,Ar-H),7.68(s,1H,Ar-H),4.46(q,J=7.1Hz,2H,OCH2),3.38(s,3H,N-CH3),1.39(t,J=7.1Hz,3H,OCH2-CH3). 13C NMR(100MHz,DMSO-d6)δ166.3,163.7,154.3,143.8,140.0,136.3,135.9,131.5,128.6,119.7,108.9,62.9,27.6,14.5.HRMS(ESI)calcdfor C 14 H 11 ClN3O5[M+H] + 336.0382, found 336.0380.

[0063] The product of the previous step, 1-methyl-4-carboxylic acid ethyl ester-6-nitro-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (0.60 g, 1.79 mmol), was dissolved in 18 mL of methanol and 18 mL of water. Iron powder (0.50 g, 8.95 mmol, 5 equiv), ammonium chloride (0.47 g, 8.95 mmol, 5 equiv) and 18 drops of concentrated hydrochloric acid were added. The reaction was carried out at 60 ° C for 4 h, and the solvent was concentrated in vacuo. The mixture was purified by column chromatography (pure dichloromethane) to obtain 0.49 g of purple solid 1-methyl-4-carboxylic acid ethyl ester-6-amino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-13), with a melting point of 200–207 ° C and a yield of 90%. 1 H NMR(400MHz,DMSO-d6)δ8.36(s,1H,Ar-H),7.26(s,1H,Ar-H),5.98(s,2H,NH2),4 .46(q,J=7.1Hz,2H,OCH2),3.31(s,3H,N-CH3),1.42(t,J=7.1Hz,3H,OCH2-CH3). 13 C NMR(100MHz,DMSO-d6)δ165.3,164.6,149.2,138.3,136.4,135.7,128.8,119.3,118.1,114.1,112.3,62.4,27.2,14.6.HRMS(ESI)calcd for C 14 H 13 ClN3O3[M+H] + 306.0640, found 306.0644.

[0064] Example 14 1-Methyl-4-carboxamide-6-amino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-14)

[0065] Compound I-13 (0.10 g, 0.33 mmol) was dissolved in 15 mL of aqueous ammonia (28%) and 15 mL of water, reacted at 60 °C for 6 h, concentrated in vacuo to remove the solvent, and purified by column chromatography (dichloromethane / methanol = 15 / 1) to obtain 0.046 g of a purple solid with a melting point of 166-174 °C and a yield of 52%. 1 HNMR(400MHz,DMSO-d6)δ9.02(s,1H,Ar-H),8.37(s,1H,CONH2),7.86(s,1H,Ar-H),7.18(s,1H,CONH2),6.54(s,2H,NH2),3.31(s,3H,N-CH3). 13 C NMR(100MHz,DMSO-d6)δ165.9,151.4,138.7,135.9,135.4,128.2,119.3,116.0,114.3,112.6,110.9,27.9,26.5.HRMS(ESI)calcd for C 12 H 10 ClN4O2[M+H] + 277.0487, found 277.0493.

[0066] Example 15 Synthesis of 1-methyl-4-formamide-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-15)

[0067] In the first step, 5 mL of concentrated nitric acid was slowly added dropwise to 10 mL of concentrated sulfuric acid under ice bath conditions, cooled to 0°C, compound I-1 (0.29 g, 1.0 mmol) was added, the temperature was slowly raised to 35°C, reacted for 4 h, 400 mL of water was added, extracted three times with 20 mL of ethyl acetate, concentrated in vacuo to remove the solvent, and purified by column chromatography (petroleum ether / dichloromethane = 2 / 1 to 1 / 1) to obtain 0.34 g of yellow solid 1-methyl-4-carboxylic acid ethyl ester-6,8-dinitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline, melting point 138-140°C, yield 77%. 1 HNMR (400MHz, CDCl3) δ8.69(s,1H,Ar-H),4.48(q,J=7.0Hz,2H,OCH2),3.34(s,3H,N-CH3),1.41(t,J=7.0Hz,3H,OCH2-CH3). 13C NMR(100MHz, CDCl3)δ165.1,163.1,156.1,136.3,134.5,133.8,130.9,128.8,124.0,121.2,121.0,63.4,27.2,14.2.HRMS(ESI)calcd for C 14 H 10 ClN4O7[M+H] + 381.0233, found 381.0237.

[0068] In the second step, 1-methyl-4-carboxylic acid ethyl ester-6,8-dinitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline (0.09 g, 0.28 mmol) was dissolved in 17 mL of ammonia water (28%) and 17 mL of water, and the reaction was carried out at 60°C for 6 h. The solution was concentrated in vacuo and desolvated, and purified by column chromatography (dichloromethane / methanol = 15 / 1) to obtain 0.065 g of purple solid 1-methyl-4-carboxylic acid ethyl ester-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline, with a melting point of 225-230°C and a yield of 68%. 1 HNMR(400MHz,DMSO-d6)δ8.36(s,1H,Ar-H),6.32(s,2H,NH2),6.14(s,2H,NH2),4 .42(q,J=7.0Hz,2H,OCH2),3.60(s,3H,N-CH3),1.40(t,J=7.0Hz,3H,OCH2-CH3). 13 C NMR(100MHz,DMSO-d6)δ165.1,164.1,142.4,140.8,133.6,132.4,130.7,119.5,118.9,107.0,105.9,61.8,29.1,14.7.HRMS(ESI)calcd for C 14 H 14 ClN4O3[M+H] + 321.0749, found 321.0742.

[0069] In the third step, the compound 1-methyl-4-carboxylic acid ethyl ester-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline (0.09 g, 0.28 mmol) was dissolved in 17 mL of ammonia water (28%) and 17 mL of water, reacted at 60 ° C for 6 h, concentrated in vacuo to remove the solvent, and purified by column chromatography (dichloromethane / methanol = 15 / 1) to obtain 0.065 g of purple solid 1-methyl-4-carboxamide-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline (I-15), melting point 227-232 ° C, yield 80%. 1 H NMR(400MHz,DMSO-d6)δ8.89(s,1H,Ar-H),8.35(s,1H,CONH2),7.64(s,1H,CONH2),6.70(s,2H,NH2),6.19(s,2H,NH2),3.60(s,3H,N-CH3).HRMS(ESI)calcd forC 12 H 11 ClN5O2[M+H] + 292.0596, found 292.0591.

[0070] Example 16 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-6-dimethylamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-16)

[0071] Compound I-13 (0.07 g, 0.23 mmol) and potassium carbonate (0.032 g, 0.46 mmol, 2 equiv) were dissolved in 5 mL DMF, stirred at room temperature for 10 minutes, iodomethane (0.098 g, 0.70 mmol, 3 equiv) was added, and the mixture was reacted at room temperature for three days. 50 mL of water was added, and the mixture was extracted three times with 10 mL of ethyl acetate respectively. The mixture was concentrated in vacuo to remove the solvent, and purified by column chromatography (pure dichloromethane) to obtain 0.068 g of a purple solid with a melting point of 174-180 °C and a yield of 87%. 1 H NMR(400MHz,DMSO-d6)δ8.33(s,1H,Ar-H),7.41(s,1H,Ar-H),4.45(q,J=6.9Hz,2H ,OCH2),3.34(s,3H,N-CH3),3.13(s,6H,N-CH3),1.41(t,J=6.9Hz,3H,OCH2-CH3). 13C NMR(100MHz,DMSO-d6)δ165.6,164.0,149.3,142.5,141.5,135.9,135.7,132.5,119.9,116.8,111.1,61.8,44.5,26.7,14.0.HRMS(ESI)calcd for C 16 H 17 ClN3O3[M+H] + 334.0953, found 334.0957.

[0072] Example 17 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-6-dibenzylamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-17)

[0073] Compound I-13 (0.07 g, 0.23 mmol) and potassium carbonate (0.032 g, 0.46 mmol, 2 equiv) were dissolved in 5 mL DMF, stirred at room temperature for 10 minutes, benzyl bromide (0.087 g, 0.51 mmol, 2.2 equiv) was added, reacted at room temperature for three days, 50 mL of water was added, extracted three times with 10 mL of ethyl acetate respectively, concentrated in vacuo to remove the solvent, and purified by column chromatography (pure dichloromethane) to obtain 0.1 g of purple solid with a melting point of 139-143 ° C and a yield of 89%. 1 H NMR (400MHz, CDCl3) δ8.55(s,1H,Ar-H),7.46(d,J=7.1Hz,4H,Ar-H),7.22(m,4H,Ar-H),7.16(m,2H,Ar-H),6.96(s ,1H,Ar-H),4.73(s,4H,N-CH2),4.59(q,J=7.1Hz,2H,OCH2),3.38(s,3H,N-CH3),1.56(t,J=7.1Hz,3H,OCH2-CH3). 13 C NMR (100MHz, CDCl3) δ166.6,164.8,150.0,144.4,140.6,139.2,136.8,136.3,135.8 ,128.7,128.0,126.8,120.4,117.6,110.4,62.2,57.9,26.7,14.4.HRMS(ESI)calcd for C 28 H 25 ClN3O3[M+H] + 486.1579, found 486.1584.

[0074] Example 18 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-6-acetylamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-18)

[0075] Compound I-13 (0.05 g, 1.64 mmol) was dissolved in 5 mL of acetic acid, and acetic anhydride (0.032 g, 3.28 mmol, 2 equiv) was added. The reaction was carried out at 120 °C for 4 hours, and 20 mL of water was added. The mixture was extracted three times with ethyl acetate and concentrated in vacuo to obtain 0.45 g of an orange solid with a melting point of 242–252 °C and a yield of 79%. 1 H NMR (400MHz, CDCl3) δ8.50(s,1H,Ar-H),8.21(s,1H,NH),6.99(s,1H,Ar-H),4.54(q,J=7. 1Hz,2H,OCH2),3.41(s,3H,N-CH3),2.34(s,3H,COCH3),1.49(t,J=7.1Hz,3H,OCH2-CH3). 13 C NMR(100MHz, CDCl3)δ166.11,164.1,152.0,141.6,139.0,136.3,135.5,127.0,119.9,118.4,109.6,62.8,26.9,23.3,14.2.HRMS(ESI)calcd for C 16 H 15 ClN3O4[M+H] + 348.0746, found 348.0740.

[0076] Example 19 Synthesis of 1-methyl-4-carboxylic acid ethyl ester-6-benzamido-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-19) and 1-methyl-4-carboxylic acid ethyl ester-6-dibenzamido-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-20)

[0077] Compound I-13 (0.05 g, 0.16 mmol) and triethylamine (0.05 g, 0.49 mmol, 3 equiv) were dissolved in 5 mL of dichloromethane. Benzoyl chloride (0.046 g, 0.33 mmol, 2 equiv) was slowly added dropwise under ice bath conditions. The mixture was reacted for 48 hours at room temperature. 20 mL of saturated sodium bicarbonate solution was added, and the mixture was extracted three times with 10 mL of ethyl acetate respectively. The mixture was concentrated in vacuo to remove the solvent, and purified by column chromatography (pure dichloromethane) to obtain the target product.

[0078] 1-Methyl-4-carboxylic acid ethyl ester-6-benzamido-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-19) is a yellow-brown solid with a melting point of 232–242°C and a yield of 32%. 1 H NMR (400MHz, DMSO-d6) δ10.57(s,1H,NH),8.46(s,1H,Ar-H),8.10(d,J=7.3Hz,2H,Ar-H),7.66–7.68(m,1H,Ar-H),7.62( s,1H,Ar-H),7.62–7.56(m,2H,Ar-H),4.41(q,J=7.1Hz,2H,OCH2),3.42(s,3H,N-CH3),1.34(t,J=7.1Hz,3H,OCH2-CH3). 13 C NMR(100MHz,DMSO-d6)δ165.9,164.0,157.7,153.4,152.0,142.1,139.8,137.2,135.7,133 .9,131.9,128.5,127.9,119.6,117.7,109.8,62.0,40.1,38.9,26.9,14.0.HRMS(ESI)calcd for C 21 H 17 ClN3O4[M+H] + 410.0902, found 410.0908.

[0079] 2-1-Methyl-4-carboxylic acid ethyl ester-6-dibenzamido-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-20) is an orange solid with a melting point of 259–265°C and a yield of 60%. 1 H NMR (400MHz, CDCl3) δ8.62(s,1H,Ar-H),7.88(d,J=7.3Hz,4H,Ar-H),7.36–7.38(m,2H,Ar-H),7.28–7.30(m,4 H,Ar-H),7.06(s,1H,Ar-H),4.43(q,J=7.1Hz,2H,OCH2),3.44(s,3H,N-CH3),1.36(t,J=7.1Hz,3H,OCH2-CH3). 13CNMR (100MHz, CDCl3) δ173.3,166.3,164.3,152.8,141.8,141.0,138.0,135.6,132.1, 130.3,129.2,128.2,126.3,120.6,118.9,109.1,62.4,27.0,14.2.HRMS(ESI)calcdfor C 28 H 21 ClN3O5[M+H] + 514.1164, found 514.1163.

[0080] Embodiment 20

[0081] The anti-tobacco mosaic virus activity of the individual compounds of the above-mentioned chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 is determined by the following procedure:

[0082] The first step is to purify tobacco mosaic virus and determine its concentration:

[0083] The purification and concentration determination of tobacco mosaic virus were carried out according to the SOP specification of tobacco mosaic virus prepared by the Laboratory of Element Analysis of Nankai University. The crude virus extract was centrifuged twice with polyethylene glycol, and the concentration was determined to be 20 μg / mL, and then refrigerated at 4°C for later use.

[0084] The second step is to prepare the pharmaceutical solution of the individual compounds of the above-mentioned chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20:

[0085] Weigh 40 mg of the individual compounds of chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 as the original drug, and then add 0.4 mL of DMF to each original drug to dissolve them to prepare 1×10 5 μg / mL stock solution, and then diluted with a Tween 80 aqueous solution with a mass percentage concentration of 1‰ to a test concentration of 500μg / mL or 100μg / mL, thereby preparing the above-mentioned chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 as individual compound pharmaceutical solutions, and in addition, taking Ningnanmycin preparation and directly diluting it with water as a control;

[0086] Step 3: In vivo protection:

[0087] Ten 3-5 leaf-stage Sansi tobacco plants with uniform growth were selected, and the whole plants were sprayed with the solutions of the individual compounds of the chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 prepared in the second step. Each treatment was repeated 3 times, and a Tween 80 aqueous solution with a mass percentage concentration of 1‰ was set as a control. After 24 hours, 500-mesh corundum was sprinkled on the leaves, and the virus solution was dipped with a brush and gently rubbed along the branch vein direction twice on the entire leaf surface. The lower side of the leaf was supported by the palm of the hand. The virus concentration was 10μg / mL. After inoculation, it was rinsed with running water. After 3 days, the number of lesions was recorded and the control effect was calculated.

[0088] Step 4: In vivo therapeutic effect:

[0089] Ten pieces of Sansi tobacco trees with uniform growth at the 3-5 leaf stage were selected, and the virus was inoculated on the whole leaves with a brush at a virus concentration of 10 μg / mL. After inoculation, the leaves were rinsed with running water. After the leaves were dried, the whole plants were sprayed with the solutions of the individual compounds of the chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 prepared in the second step. Each treatment was repeated 3 times, and a Tween 80 aqueous solution with a mass percentage concentration of 1‰ was set as a control. After 3 days, the number of lesions was recorded and the control effect was calculated.

[0090] Step 5: Live inactivation:

[0091] Ten pieces of Sansi tobacco with uniform growth in the 3-5 leaf stage were selected respectively, and the individual compound solutions of the chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 prepared in the second step were mixed with an equal volume of virus juice for passivation for 30 minutes, and then friction inoculated. The virus concentration was 20μg / mL, and the inoculation was immediately rinsed with running water. This was repeated 3 times. A Tween 80 aqueous solution with a mass percentage concentration of 1‰ was set as a control. After 3 days, the number of lesions was counted and the results were calculated.

[0092] The results of the determination of the anti-tobacco mosaic virus activity of the individual compounds represented by the above-mentioned chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 are shown in Table 1.

[0093] Table 1. Anti-TMV activity test results of individual compounds shown in chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20:

[0094]

[0095] Table 1 Chloropyrrolo[4,3,2-de]quinoline alkaloids I-1~I-20 have good anti-plant virus activity. Under the same test conditions, most of them are better than the commercial variety ribavirin. Compounds Ⅰ-3~Ⅰ-4, Ⅰ-7 and Ⅰ-8 show higher anti-TMV activity than ningnanmycin at 500μg / mL, and have development value.

[0096] Embodiment 21

[0097] The anti-potato virus Y activity of the individual compounds of the above chloropyrrolo[4,3,2-de]quinoline alkaloids I-1 to I-20 was determined in the same manner as in Example 35, with Chenopodium album as the virus lesion host. The number of local lesions was recorded 6-7 days after inoculation, and the results were calculated. The specific activity test results are shown in Table 2.

[0098] Table 2 Anti-PVY activity test results of compounds I-2, I-3, I-7 and I-8

[0099]

[0100] Table 2 shows that chloropyrrolo[4,3,2-de]quinoline alkaloids I-2, I-3, I-7 and I-8 have excellent antiviral activity against potato virus Y and have good application prospects.

[0101] The percentages in the above embodiments are all by mass.

[0102] The raw materials and reagents involved in the above examples are all commercially available, and the chemical reaction processes are within the skill of those skilled in the art.

[0103] Matters not covered by the present invention are known technologies.

Claims

1. A chloropyrrolo[4,3,2-de]quinoline alkaloid, characterized in that it is one of the compounds shown in I-1 to I-20:

2. The method for preparing chloropyrrolo[4,3,2-de]quinoline alkaloids according to claim 1, characterized in that: Compounds I-1 to I-20 can be prepared by one of the following methods: Synthesis of compound I-1: prepared according to the method shown in equation 1, firstly, using DMF as solvent, 6-chloroindigo carmine reacts with MeI under the action of K2CO3 to undergo N-methylation reaction to obtain 1-methyl-6-chloroindigo carmine; then, in the presence of acetic acid, 1-methyl-6-chloroindigo carmine and ethyl 2-oxo-3-(triphenylphosphine) propionate are heated to 75°C in tetrahydrofuran solvent for reaction for 12 hours to obtain compound E-1-methyl-3-(ethyl 2-oxopropionate-1-enyl)-2-oxo-6-chloroindole; subsequently, under N2 protection conditions, the mixture is treated with di-tert-butyl azodicarboxylate and triphenylphosphine for reaction at room temperature for 5 hours, and then a mixed solution of anhydrous ethanol and H2SO4 (2.5M) is reacted at 60°C for 1 hour to obtain compound I-1; Synthesis of compounds I-2 to I-4: Prepared according to the method of formula 2, firstly, compound I-1 is hydrolyzed in a tetrahydrofuran-water mixed solution of sodium hydroxide, and after adjusting to acidity with hydrochloric acid, compound I-2 containing a carboxylic acid group can be obtained; subsequently, compound I-3 is amidated with n-butylamine under the action of O-benzotriazole-tetramethyluronium hexafluorophosphate and N,N-diisopropylethylamine; oxalyl chloride is added dropwise to acetonitrile in which triphenylphosphine is dissolved, and then a mixed solution of acetonitrile containing compound I-2 and aniline is added to obtain compound I-4; Synthesis of compounds I-5 to I-6: Prepared according to the method of equation 3, firstly, compound I-1 is treated with ammonia water at 60°C for 6 hours to obtain compound I-5, which also contains a small amount of I-6; compound I-5 is stirred in a methanol solution containing a small amount of concentrated hydrochloric acid for 1 hour to obtain compound I-6; Synthesis of compounds I-7 to I-12: Prepared according to the method of formula 4, compound I-1 is stirred in a mixed solution of hydrazine hydrate and methanol for 1 hour to achieve the preparation of compound I-7; compound I-7 is then treated with a methanol solution containing concentrated hydrochloric acid to obtain compound I-8; hydrazide compound I-8 and different substituted aldehyde compounds are refluxed in a methanol solvent for 2-6 hours to obtain compounds I-9 to I-12; Synthesis of compounds I-13 to I-15: Prepared according to the method of formula 5, firstly, compound I-1 is treated in a sulfuric acid-nitric acid mixture, and reacted at 0°C for 3 hours to obtain a mononitration product 1-methyl-4-ethylformate-6-nitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline, and reacted at 0°C slowly to 35°C for 4 hours to obtain a dinitration product 1-methyl-4-ethylformate-6,8-dinitro-2-oxo-7-chloro-1,2-dihydropyrrole [4,3,2-de] quinoline. -7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline; the nitration product can be reduced by iron powder to achieve the synthesis of 1-methyl-4-ethylformate-6-amino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline (I-13) and 1-methyl-4-ethylformate-6,8-diamino-2-oxo-7-chloro-1,2-dihydropyrrolo[4,3,2-de]quinoline; and then treated with ammonia water to obtain compounds I-14 and I-15; Synthesis of compounds I-16 to I-17: Prepared according to the method of equation 6, using potassium carbonate as a base and DMF as a solvent, compound I-13 reacts with methyl iodide to obtain compound I-16, and reacts with benzyl bromide to obtain compound I-17; Synthesis of compounds I-18 to I-20: Prepared according to the method of equation 7, compound I-13 is reacted with acetic anhydride in acetic acid at 120°C for 4 hours to obtain compound I-18; under ice bath conditions, with triethylamine as an acid-binding agent, compound I-13 is reacted with benzoyl chloride to obtain compounds I-19 and I-20; 3. The use of chloropyrrolo[4,3,2-de]quinoline alkaloids as claimed in claim 1, characterized in that: Used as an anti-plant virus agent, the plant virus is tobacco mosaic virus, pepper virus, rice virus, tomato virus, sweet potato virus, potato virus Y, cucurbit virus or corn dwarf mosaic virus.

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