Carboline compound as well as preparation method and application thereof

Abstract

The invention relates to a carboline compound as well as a preparation method and application thereof.The preparation method comprises the steps that D-tryptophan serves as a substrate, an acetaldehyde solution is added, sulfuric acid is slowly dropwise added, a compound 1 obtained through reaction is dissolved in dichloromethane, then a Des-Martin reagent is added, heating reflux is performed, saturated sodium bicarbonate and sodium thiosulfate are added for quenching, and reduced pressure distillation is performed to obtain a compound 2; dissolving the compound 2 in dichloromethane, dropwise adding triethylamine and thionyl chloride, and performing reflux reaction to obtain a compound 3; dissolving the compound 3 in tetrahydrofuran, adding sodium cyanide, then adding a compound 4, monitoring the reaction process by TLC, removing the solvent by rotary evaporation after the reaction is completed, adding ethyl acetate, slowly dropwise adding a small amount of water into an ice bath, extracting with ethyl acetate, drying with anhydrous sodium sulfate, and then performing column chromatography purification to obtain the target compound a1-a12. The preparation method is simple, the synthesis process is simple, the product purity is high, escherichia coli and staphylococcus aureus can be effectively inhibited, and good ship antifouling application prospects are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of compounds, its preparation method and the use in ship antifouling. BACKGROUND

[0002] Ship often suffers from marine organisms such as seaweed, barnacles and other marine organisms in the ocean, which is called biofouling. Biofouling can increase the weight and sailing resistance of the ship, thereby increasing fuel consumption (fuel consumption is about 40% more at the same speed); when marine organisms attach to the ship bottom, it also causes a series of complex physical and chemical changes on the surface of the ship, greatly accelerating the corrosion of the ship bottom steel plate and reducing the service life of the ship. According to incomplete statistics, the economic loss caused by biofouling to various underwater engineering facilities and ship equipment can reach tens of billions of dollars per year worldwide.

[0003] In order to reduce the harm of fouling, many countries have carried out research on environmentally friendly ship antifouling technology and have achieved certain results. Among them, painting antifouling paint has become the most widely used method due to its good antifouling effect, strong feasibility, low one-time investment and no need for management. So far, almost all ship antifouling has adopted antifouling paint. Antifouling paint is mainly composed of five parts: resin, antifouling agent, filler, solvent and auxiliary materials. By mixing them thoroughly and applying them to the surface of the ship to form an antifouling layer. The antifouling agent is the most important and effective component, and is the core of the antifouling paint. Antifouling paint works by controlled release of the antifouling agent, which interacts with marine fouling organisms to prevent marine organisms from attaching to the surface of the object.

[0004] Since the development of antifouling paint with organic tin (TBT) as antifouling agent in the 1970s, it has been favored by the shipbuilding and shipping departments around the world due to its broad spectrum, long antifouling period and low cost. However, in the early 1980s, France first discovered that the antifouling agent released by the paint had a long toxic decay period. This toxic compound was deposited in the sea mud and accumulated in the organisms for a long time, causing serious environmental pollution problems, which attracted worldwide attention. The International Maritime Organization under the United Nations passed a resolution to ban the use of TBT antifouling paint. In the face of this severe situation, various countries have begun to develop long-acting environmentally friendly antifouling agents.

[0005] Cuprous oxide is currently the most important and widely used toxic agent in antifouling paint, which can effectively kill marine fouling organisms and is lowly toxic to humans. It has been used in formulations for decades. Although cuprous oxide is less harmful to the environment than organic tin, it still has the following problems:

[0006] (1) Copper as a heavy metal element, has a certain toxicity, and can not be biodegraded, a large number of cuprous oxide in the ocean or harbor accumulation, can lead to a large number of seaweed death, serious damage to the ecological balance;

[0007] (2) Cu2O final product basic copper carbonate will precipitate accumulated in the seabed, reduce the respiration rate of mussels and other shellfish, damage their growth process.

[0008] The traditional antifouling paint uses antifouling agent (such as TBT) to cause great negative impact on the environment, and the antifouling paint developed by cuprous oxide will also be prohibited. Therefore, it is urgent to find an environmentally friendly antifouling agent. Natural product active substance is the main source of environmentally friendly antifouling agent, and is the development direction of future antifouling agent. Natural product antifouling agent has the advantages of low toxicity and no pollution, but the extraction of active substance is not only difficult to operate, the steps are complicated, and the content is particularly low, which is difficult to industrialize. SUMMARY

[0009] In order to overcome the shortcomings of the prior art, develop an environmentally friendly antifouling agent, the purpose of the present application is to provide a karylin compound, its preparation method and its ship antifouling activity, which is synthesized by using D-tryptophan as a substrate and Dess-Martin as a catalyst, has the environmental protection characteristics of low toxicity and easy degradation, replaces the cuprous oxide antifouling agent with high toxicity, reduces environmental pollution, and improves the antifouling activity. Escherichia coli and Staphylococcus aureus have good inhibitory effect.

[0010] In order to achieve the above purpose, the present application adopts the following scheme:

[0011] The karylin compound has a general formula (I):

[0012]

[0013] R is an alkyl group, a single-taken aryl group selected from any one of a1 to a12:

[0014]

[0015] The synthesis route of the karylin compound with formula (I) is as follows:

[0016]

[0017] The specific synthesis method of the above karylin compound is as follows:

[0018]

[0019] Step one, add acetaldehyde and water to D-tryptophan and stir to mix, slowly add sulfuric acid dropwise, and stir the reaction system at room temperature. After the reaction is complete, the reaction solution is filtered under reduced pressure to obtain compound 1, which is directly used in the next step.

[0020]

[0021] Step two, compound 1 obtained in step one is dissolved in dichloromethane, then Dess-Martin reagent is added, and reflux is performed at 55±2°C. The reaction is complete as detected by TLC. Ethyl acetate is added for dilution, and the system is transferred to room temperature. Saturated sodium bicarbonate and sodium thiosulfate are added for quenching. The crude product is partitioned in water and ethyl acetate. The organic phase is washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and distilled under reduced pressure to obtain compound 2.

[0022]

[0023] Step three, compound 2 obtained in step two is dissolved in dichloromethane, triethylamine is added, and dichlorosulfoxide SOCl2 is slowly added dropwise in an ice water bath. The system is warmed to 55°C, and reflux is performed for 1.5 h. After the system is cooled, the solvent and excess SOCl2 are removed by distillation under reduced pressure to obtain the corresponding compound 3.

[0024]

[0025] Step four, compound 4 is dissolved in tetrahydrofuran THF, sodium cyanide NaH is added, then compound 3 obtained in step three is added, and stirring is performed at room temperature. The reaction progress is monitored by TLC. After the reaction is complete, the solvent is removed by rotary evaporation. A small amount of water is slowly added dropwise in an ice bath. The liquid is separated, and the ethyl acetate phase is extracted. The ethyl acetate phases are combined, washed twice with saturated NaCl, dried over anhydrous sodium sulfate, and purified by column chromatography to obtain the target compound a1-a12.

[0026] Compound 4 is selected from acetyl hydrazide, propionyl hydrazide, butyryl hydrazide, valeryl hydrazide, caproyl hydrazide, benzoyl hydrazide, 2-methylbenzoyl hydrazide, 3-methylbenzoyl hydrazide, 4-methylbenzoyl hydrazide, 2-fluorobenzoyl hydrazide, 3-fluorobenzoyl hydrazide, and 4-fluorobenzoyl hydrazide. Correspondingly, compounds a1-a12 are prepared.

[0027] The above compound is used for ship antifouling agents, and the two bacteria involved are Escherichia coli and Staphylococcus aureus.

[0028] Beneficial effects

[0029] The carboline compounds provided by this invention are characterized by simple structure, readily available raw materials, mild reaction conditions, and simple process. The synthesized compounds exhibit environmentally friendly properties such as low toxicity and easy degradation, replacing the more toxic cuprous oxide antifouling agent. The synthesized compounds also show inhibitory activity against Escherichia coli and Staphylococcus aureus, demonstrating excellent application prospects. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the embodiments.

[0031] This invention provides a method for synthesizing the aforementioned carboline compounds, as detailed below:

[0032] Step 1: Compound 1 Synthesis

[0033]

[0034] Weigh 1.0 g (5 mmol) of D-tryptophan into a 50 mL round-bottom flask, add 1.7 mL (30 mmol, 3.0 eq.) of acetaldehyde solution, and then add 0.5 M sulfuric acid (0.3 mL) dropwise. Stir the reaction at room temperature. After the reaction is complete, filter the mixture and dry the filter cake under vacuum to obtain compound 1 (0.7 g, 77%).

[0035] Step 2: Compound 2 Synthesis

[0036] Compound 2 (460 mg, 2 mmol) was weighed into a dry round-bottom flask, dissolved in 10 mL of dichloromethane, and then Dess-Martin reagent (1.697 g, 4 mmol) was weighed into the round-bottom flask. The mixture was refluxed at 50 °C for 2 h, and the reaction was monitored by TLC until complete. The mixture was diluted with 50 mL of ethyl acetate, transferred to room temperature, and quenched with saturated sodium bicarbonate and sodium thiosulfate. The crude product was partitioned in water and ethyl acetate, washed with saturated sodium chloride solution, dried over anhydrous sodium sulfate, filtered, and purified by column chromatography under reduced pressure to obtain compound 3 (361.6 mg, 80%).

[0037] Step 3: Compound 3 Synthesis

[0038] Compound 2 (2.8 g, 12 mmol) was weighed into a 100 mL dry round-bottom flask, 15 mL of dichloromethane was added, and triethylamine (2.5 mL, 18 mmol) was added dropwise. The flask was placed in an ice-water bath at 0 °C, and 1.3 mL (18 mmol, 1.5 eq.) of thionyl chloride was slowly added dropwise. The mixture was heated to 55 °C and refluxed for 1.5 h. After the reaction was complete, the solvent and excess thionyl chloride were removed by rotary evaporation to obtain compound 3 (2.34 g, 86%).

[0039] Step four: Synthesis of compounds a1-a12

[0040] Compound 3 was weighed and dissolved in THF, then sodium cyanide (NaCN) was added, and the corresponding compound 4 was added. The reaction was stirred at room temperature, and the progress of the reaction was monitored by TLC. After the reaction was completed, the solvent was removed by rotary evaporation. Appropriate ethyl acetate was added, and a small amount of water was slowly added dropwise in an ice bath. After separation, the ethyl acetate phase was extracted, washed twice with saturated NaCl, dried over anhydrous sodium sulfate, and purified by column chromatography to obtain the target compound a1-a12.

[0041] Examples 1-12 were prepared by reacting compound 3 with the corresponding alkyl or aryl compound (compound 4) used to synthesize a1-a12. Compound 4 was selected from acetylhydrazide, propionylhydrazide, butyrylhydrazide, valerylhydrazide, caproylhydrazide, benzoylhydrazide, 2-methylbenzoylhydrazide, 3-methylbenzoylhydrazide, 4-methylbenzoylhydrazide, 2-fluorobenzoylhydrazide, 3-fluorobenzoylhydrazide, and 4-fluorobenzoylhydrazide. The specific compounds are shown below:

[0042] Example 1 N'-acetyl-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a1): Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.73 (s, 1H), 11.13 (s, 1H), 10.06 (s, 1H), 8.35 (s, 1H), 8.18 (d, J = 7.1 Hz, 1H), 7.61 - 7.25 (m, 3H), 2.82 (s, 3H), 1.90 (s, 3H). MS (API(+)) calcd for C 15 H 15 N4O2 + [M+H] + : 283.12; found: 283.10.

[0043] Example 2

[0044] 1-methyl-N'-propionyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a2).

[0045] Yield: 91%. 1 ​​​H NMR (400 MHz, DMSO-d6) δ 11.68 (s, 1H), 11.23 (s, 1H), 10.05 (s, 1H), 8.31 (s, 1H), 8.14 (d, J = 6.3 Hz, 1H), 7.66 - 7.34 (m, 3H), 2.87 (s, 3H), 2.13 (q, 2H), 1.03 (t, 3H). MS (API(+)) calcd for C 16 H 16 N4O2 + [M+H] + :296.13; found: 296.15.

[0046] Example 3 Synthesis of N'-butyryl-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a3). Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.79 (s, 1H), 11.16 (s, 1H), 10.11 (s, 1H), 8.31 (s, 1H), 8.17 (d, J = 6.2 Hz, 1H), 7.65 - 7.23 (m, 3H), 2.87 (s, 3H), 2.18 (q, 2H), 1.64 - 1.58 (m, 2H), 0.95 (t, 3H). MS (API(+)) calcd for C 17 H 19 N4O2 + [M+H] + :311.15; found: 311.12.

[0047] Example 4 Synthesis of

[0048] 1-methyl-N'-pentanoyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a4).

[0049] Yield: 91%. 1H NMR (400 MHz, DMSO-d6) δ 11.77 (s, 1H), 11.22 (s, 1H), 10.17 (s, 1H), 8.24 (s, 1H), 8.17 (d, J = 6.4 Hz, 1H), 7.63 - 7.23 (m, 3H), 2.84 (s, 3H), 2.12 (q, 2H), 1.66 - 1.60 (m, 4H), 0.96 (t, 3H). MS (API(+)) calcd for C 18 H 21 N4O2 + [M+H] + : 325.17; found: 325.21.

[0050] Example 5 Synthesis of N'-hexanoyl-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a5). Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.75 (s, 1H), 11.21 (s, 1H), 10.15 (s, 1H), 8.27 (s, 1H), 8.12 (d, J = 6.7 Hz, 1H), 7.62 - 7.20 (m, 3H), 2.86 (s, 3H), 2.15 (q, 2H), 1.68 - 1.60 (m, 4H), 0.97 (t, 3H). MS (API(+)) calcd for C 19 H 23 N4O2 + [M+H] + : 339.18; found: 339.13.

[0051] Example 6 Synthesis of N'-hexanoyl-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a6). Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.76 (s, 1H), 11.23 (s, 1H), 10.11 (s, 1H), 8.25 (s, 1H), 8.12 - 7.20 (m, 9H), 2.87 (s, 3H). MS (API(+)) calcd for C 20 H 17 N4O2 + [M+H] +: 345.14; found: 345.13.

[0052] Example 7 Synthesis of

[0053] 1 -methyl- N '-(2-methylbenzoyl)-9H-pyrido[3, 4-b]indole-3-carbohydrazide (a7).

[0054] Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.80 (s, 1H), 11.28 (s, 1H), 10.15 (s, 1H), 8.27 (s, 1H), 8.13 - 7.24 (m, 8H), 2.84 (s, 3H), 2.46 (s, 3H). MS (API(+)) calcd for C 21 H 19 N4O2 + [M+H] + : 359.41 ; found: 359.46.

[0055] Example 8 Synthesis of

[0056] 1 -methyl- N '-(3-methylbenzoyl)-9H-pyrido[3, 4-b]indole-3-carbohydrazide (a8).

[0057] Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.80 (s, 1H), 11.28 (s, 1H), 10.15 (s, 1H), 8.27 (s, 1H), 8.13 - 7.24 (m, 8H), 2.84 (s, 3H), 2.46 (s, 3H). MS (API(+)) calcd for C 21 H 19 N4O2 + [M+H] + : 359.41 ; found: 359.46.

[0058] Example 9 Synthesis of

[0059] 1 -methyl- N '-(4-methylbenzoyl)-9H-pyrido[3, 4-b]indole-3-carbohydrazide (a9).

[0060] Yield: 91%. 1 H NMR(400MHz,DMSO-d6)δ11.80(s,1H),11.27(s,1H),10.17(s,1H),8.27(s,1H),8.17-7.24(m,8H),2.87(s,3H),2.43(s,3H).MS(API(+))calcd for C 21 H 19 N4O2 + [M+H] + :359.41; found:359.46.

[0061] Example 10 Synthesis

[0062] N'-(2-fluorobenzoyl)-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide(a10).

[0063] Yield: 91%. 1 H NMR(400MHz,DMSO-d6)δ11.78(s,1H),11.26(s,1H),10.16(s,1H),8.25(s,1H),8.18-7.22(m,8H),2.89(s,3H).MS(API(+))calcd for C 20 H 16 FN4O2 + [M+H] + 363.13; found: 363.09.

[0064] Example 11 Synthesis

[0065] N'-(3-fluorobenzoyl)-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide(a11).

[0066] Yield: 91%. 1 H NMR(400MHz,DMSO-d6)δ11.71(s,1H),11.22(s,1H),10.14(s,1H),8.22(s,1H),8.26-7.27(m,8H),2.88(s,3H).MS(API(+))calcd for C 20 H 16 FN4O2 +[M+H] + : 363.13; found: 363.09.

[0067] Example 12 Synthesis of N'-(4-fluorobenzoyl)-1-methyl-9H-pyrido[3,4-b]indole-3-carbohydrazide (a12).

[0068] Yield: 91%. 1 H NMR (400 MHz, DMSO-d6) δ 11.79 (s, 1H), 11.25 (s, 1H), 10.18 (s, 1H), 8.25 (s, 1H), 8.21-7.21 (m, 8H), 2.84 (s, 3H). MS (API(+)) calcd for C 20 H 16 FN4O2 + [M+H] + : 363.13; found: 363.09.

[0069] Example 13: Determination of bactericidal activity of the synthesized compounds

[0070] The bacteriostatic activity of the target products a1-a12 on staphylococcus aureus and escherichia coli was determined by microdilution method. The strains were purchased from China General Microbiological Culture Collection Center.

[0071] The sterile test tubes with 2 mL of liquid medium were used by double dilution method in test tube, and the test tube inoculated with bacteria without adding the test compound was used as positive control, and the test tube without adding the test compound and inoculating bacteria was used as negative control. The initial mass concentration of the drug was 1 g / L, which was double diluted in turn and mixed uniformly. 200 μL of bacterial suspension was added to each test tube to make the final bacterial liquid concentration 10 4 ~ 10 5 cfu / mL (cfu refers to a single colony formed on agar plate after culture). After 24 h of shaking culture, the minimum bacteriostatic mass concentration was determined according to the growth of bacteria in the test tube.

[0072] According to the above judgment, the detection results of the fluorine-containing heterocyclic compounds on the two kinds of bacteria are shown in Table 1.

[0073] Table 1 MIC values of the test compounds a1-a12 on two kinds of bacteria (unit: g / L)

[0074]

[0075] The results of Table 1 show that most of the prepared compounds exhibit good inhibitory activity, and the target compounds 8 and 11 have strong inhibitory effect on E. coli and S. aureus.

[0076] The target compounds 8 and 11 provided by the present application not only have higher antifouling activity than traditional TBTO and cuprous oxide, but also have outstanding antifouling activity among similar indole antifouling compounds, for example, the performance of the product is better than that of commercial TBG (the minimum inhibitory mass concentration of TBG to the two bacteria is 0.0625 and 0.1250 g / L). Compared with the antifouling activity disclosed in the patent (ZL201811465472.9) granted by the inventor in 2018 (the best activity of the compound is 250 ug / mL, i.e. 0.25 g / L), the antifouling activity of the present application is obviously improved (0.0313 g / L). Compared with the invention patent (CN201611113112.3) disclosed by the inventor on December 7, 2016 (the antifouling activity of the compound is 0.0625 g / L, 0.125 g / L or 0.250 g / L, respectively), the antifouling activity of the present application is also obviously improved. The patent application file (CN201310098503.2) submitted by Yantai Coastal Research of Chinese Academy of Sciences discloses the application of halogenated indole and its derivatives as marine antifouling agents, and the activity range of the compound is 0.84 mg / L-18.9 mg / L, which is obviously lower than the antifouling activity (0.0313 g / L) of the present application.

[0077] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A compound of the carboline class, characterized in that, The chemical structure of formula (I): Formula I wherein R is an alkyl group selected from any one of a1 to a12, a monosubstituted aryl group: 。 2. The method of claim 1, wherein the method is characterized by, The reaction is as follows: 。 3. The method for preparing carboline compounds according to claim 2, characterized in that, The steps are as follows: Step one, add acetaldehyde solution to D-tryptophan and stir to mix evenly, slowly add sulfuric acid dropwise, and place the reaction system at room temperature for stirring reaction; after the reaction is complete, perform vacuum filtration on the reaction liquid to obtain compound 1, which is directly used in the next step; Step two, dissolve compound 1 obtained in step one in dichloromethane, then add Dess-Martin reagent, heat to reflux, and track the reaction completion by TLC; dilute with ethyl acetate, transfer to room temperature, quench with saturated sodium bicarbonate and sodium thiosulfate, distribute the crude product in water and ethyl acetate, wash the organic phase with saturated sodium chloride solution, dry over anhydrous sodium sulfate, perform vacuum filtration, and distill under reduced pressure to obtain compound 2; Step three, dissolve compound 2 obtained in step two in dichloromethane, drop in triethylamine, slowly add dichlorosulfoxide in an ice water bath, warm to reaction temperature, and reflux the reaction; after the system cools, remove the solvent and excess SOCl2 by distillation under reduced pressure to obtain the corresponding compound 3; Step four, dissolve compound 4 in tetrahydrofuran, add sodium cyanide, then add compound 3, stir at room temperature, monitor the reaction progress by TLC, and after the reaction is complete, remove the solvent by rotary evaporation, slowly add a small amount of water dropwise in an ice bath, separate the liquid, extract with ethyl acetate, combine the ethyl acetate phases, wash twice with saturated NaCl, dry over anhydrous sodium sulfate, and purify by column chromatography to obtain the target compound a1-a12.

4. The method for preparing carboline compounds according to claim 3, characterized in that, Compound 4 is selected from acetyl hydrazide, propionyl hydrazide, butyryl hydrazide, valeryl hydrazide, caproyl hydrazide, benzoyl hydrazide, 2-methylbenzoyl hydrazide, 3-methylbenzoyl hydrazide, 4-methylbenzoyl hydrazide, 2-fluorobenzoyl hydrazide, 3-fluorobenzoyl hydrazide, and 4-fluorobenzoyl hydrazide.

5. The method for preparing carboline compounds according to claim 3, characterized in that, The reaction temperature of steps two and three is 55±2°C, and the reflux reaction time of step three is 1.5 h.

6. Use of the compound of claim 1 for ship antifouling.

7. Use according to claim 6, characterized in that The bacteria involved in the antifouling are Escherichia coli and Staphylococcus aureus.

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