A chlorospirocyclic indole ketone compound, its preparation method and application

Abstract

This invention discloses a chlorospirocyclic indole ketone compound, its preparation method, and its applications. It provides a novel 3,2'-pyrrolidinyl-spirocyclic indole ketone compound containing a continuous quaternary carbon chiral center. Using inexpensive and readily available raw materials and quinine aromatic amide derivatives with excellent asymmetric catalytic performance, a novel 3,2'-pyrrolidinyl-spirocyclic indole structure containing a continuous quaternary carbon chiral center is constructed in one step. Activity evaluation revealed that this class of compounds exhibits good to excellent inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA), demonstrating certain antibacterial activity. This invention provides a new approach for the development of novel antibiotics.

Description

Technical Field

[0001] This invention belongs to the field of fine organic chemistry and biomedicine, and specifically relates to the construction of a chlorospirocyclic indole ketone compound by an asymmetric 3+2 cycloaddition reaction, its preparation method, and its application in antibacterial agents. Background Technology

[0002] Spirocyclic indolones are an important structural backbone found in a large number of biologically active natural products and heterocyclic compounds. In particular, pyrrolidinyl spirocyclic indolone structures are the dominant backbones of many drug molecules and have been reported to possess a variety of biological activities, including antibacterial, anticancer, antimalarial, antiplatelet, and antiviral activities (Expert Opin. Drug Discovery, 2020, 15, 603-625). For example, rhynchophylline plays an important role in regulating calcium and potassium channels, thereby protecting the brain from neurodegenerative diseases and related effects.

[0003] Cycloaddition reactions are widely used in the synthesis of complex cyclic compounds due to their high atom utilization. Among them, the 3+2 cycloaddition reaction is one of the important methods for realizing carbon-carbon, carbon-heteroatom bonds, and helical ring supports. According to literature reports, spirocyclic indolones can be cycloadded chirally via indigo-derived ketamines (Chem. Commun, 2013, 49, 7213-7215). To date, scientists have constructed a series of pyrrolidinyl spirocyclic indolone derivatives; however, reports on the construction of pyrrolidinyl spirocyclic indolones with a trifluoromethyl, continuously quaternary carbon chiral center via asymmetric catalytic (3+2) cycloaddition reactions are still relatively few.

[0004] Therefore, exploring simple and universal synthetic routes to construct 3,2'-pyrrolidinyl-spirocyclic indole ketones is of great significance in both organic chemistry and medicinal chemistry. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a chlorospirocyclic indolone compound, its preparation method, and its applications. Through rational reaction design, and under the action of a quinine-based aromatic amide derivatization catalyst, the present invention successfully achieves the asymmetric 3+2 cycloaddition construction of a spirocyclic indolone with a continuous quaternary carbon chiral center by reacting an indigo-derived ketone imine with a (Z)-α-chloronitroolefin. The compound exhibits excellent inhibitory activity against methicillin-resistant Staphylococcus aureus, providing a new option for antibacterial agents.

[0006] The first aspect of the present invention provides a chlorospirocyclic indolone compound with the structural formula shown in formula (I):

[0007]

[0008] In formula (Ⅰ), R 2 It can be a single substitution or multiple substitution, wherein the multiple substitution includes adjacent, para, and meta substitution, and the R 1 R 2 Ar, independently, is hydrogen, methoxy, o-methoxybenzyl, trifluoromethoxybenzyl, o-fluorobenzyl, o-chlorobenzyl, o-bromobenzyl, m-bromobenzyl, p-bromobenzyl, o-iodobenzyl, benzyl, o-trifluoromethylbenzyl, o-methylbenzyl, phenyl, dimethylphenyl, p-methylphenyl, p-methoxyphenyl, p-nitrophenyl, p-trifluoromethylphenyl, p-fluorophenyl, p-chlorophenyl, p-bromophenyl, p-iodophenyl, o-methoxyphenyl, o-methylphenyl, o-nitrobenzene. The following is a list of the following: methyl, o-trifluoromethylphenyl, o-bromophenyl, o-fluorophenyl, o-chlorophenyl, o-iodophenyl, m-methylphenyl, m-methoxyphenyl, m-trifluoromethylphenyl, m-fluorophenyl, m-chlorophenyl, m-bromophenyl, m-iodophenyl, methyl, allyl, ethynyl, fluorine, chlorine, bromine, iodine, nitro, trifluoromethyl, naphthalene, furan, thiophene, pyrrole, benzofuran, benzothiazole, 5,6,7,8-tetrahydro-2-methoxynaphthyl, 2-methoxynaphthalene.

[0009] Furthermore, in equation (Ⅰ), R 1 It is any one of hydrogen, methyl, phenyl, and benzyl; R 2 Ar is any one of hydrogen, 5-bromo, 5-chloro, 5-methyl, 6-methoxy, 6-fluoro, 7-methyl, and 7-bromo; Ar is any one of phenyl, p-chlorophenyl, p-bromophenyl, p-fluorophenyl, p-methylphenyl, p-methoxyphenyl, p-nitrophenyl, methyl p-formate phenyl, o-bromophenyl, o-chlorophenyl, o-methylphenyl, m-chlorophenyl, m-methylphenyl, 5,6,7,8-tetrahydro-2-methoxynaphthyl, 2-methoxynaphthyl, benzothiophene, furan, and thiophene.

[0010] Furthermore, the compound represented by formula (Ⅰ) is one of the following:

[0011] (1)R 1 When it is hydrogen, R 2 Ar is hydrogen, and Ar is phenyl;

[0012] (2)R 1 When it is methyl, R 2 Ar is hydrogen, and Ar is phenyl;

[0013] (3)R 1 When R is phenyl, 2 Ar is hydrogen, and Ar is phenyl;

[0014] (4)R 1 When it is benzyl, R 2 Ar is any one of hydrogen, 5-bromo, 5-chloro, 5-methyl, 6-methoxy, 6-fluoro, 7-methyl, and 7-bromo, and Ar is phenyl.

[0015] (5)R 1 When it is benzyl, R2 is hydrogen, and Ar is any one of phenyl, p-chlorophenyl, p-bromophenyl, p-fluorophenyl, p-methylphenyl, p-methoxyphenyl, p-nitrophenyl, methyl p-formate phenyl, o-bromophenyl, o-chlorophenyl, o-methylphenyl, m-chlorophenyl, m-methylphenyl, 5,6,7,8-tetrahydro-2-methoxynaphthyl, 2-methoxynaphthyl, benzothiophene, furan, and thiophene.

[0016] Furthermore, the 3,2'-pyrrolidinyl-spirocyclic indole ketone compound shown in formula (Ⅰ) is one of the following:

[0017]

[0018] A second aspect of the present invention provides a method for preparing chlorospirocyclic indolone compounds, the method specifically comprising:

[0019] In an air atmosphere, under the action of solvent and catalyst, the compound shown in formula (II) and the compound shown in formula (III) were magnetically stirred for 3 h at room temperature of 25-30℃. The reaction was monitored by TLC until it was complete. The reaction solution was rotary evaporated under reduced pressure until no liquid flowed out, and a yellow oily liquid was obtained. The yellow oily liquid was subjected to silica gel column chromatography with petroleum ether and ethyl acetate in a volume ratio of 30:1 as eluent. The eluent with an Rf value of 0.2-0.4 was collected and rotary evaporated under reduced pressure to dryness to obtain the white foamy solid 3,2'-pyrrolidinyl-spirocyclic indole ketone compound shown in formula (I).

[0020] The catalyst is a quinine derivative, namely an aromatic amide derivative or a quinine aromatic amide derivative of quinine.

[0021] The organic solvent includes any one of dichloromethane, 1,2-dichloroethane, chloroform, toluene, and ethyl acetate, preferably dichloromethane; the reaction formula is as follows:

[0022]

[0023] In formula (Ⅰ), R 1 R 2 In the same formula (II), R 1 R 2 Ar in equation (Ⅰ) is the same as Ar in equation (Ⅲ).

[0024] Furthermore, the catalyst is any one of quinine aromatic amide derivatives C1, C2, and C3:

[0025]

[0026] Further, the molar ratio of the compound shown in formula (II) to the compound shown in formula (III) is 1:1-5, preferably 1:1.5; the molar ratio of the compound shown in formula (II) to the catalyst is 1:0.01-0.1, preferably 1:0.1; the solvent volume is 5-20 mL / mmol based on the amount of compound (II), preferably 10 mL / mmol.

[0027] A third aspect of the invention provides the use of 3,2'-pyrrolidinyl-spirocyclic indolone compounds in the preparation of antibacterial agents.

[0028] Furthermore, the antibacterial agent is an antibacterial agent against methicillin-resistant Staphylococcus aureus. This invention, through rational reaction design, successfully realized spirocyclic indole ketones with continuous quaternary carbon chiral centers by reacting indigo-derived nitroolefins with nucleophiles under the action of a quinine aromatic amide derivatization catalyst. A concise and efficient synthetic strategy was developed, providing a more direct and convenient approach for compounds with multi-pharmacophore combinations containing multiple heteroatom continuous quaternary carbon chiral centers, such as 3,2'-pyrrolidinyl-spirocyclic indole ketones. Activity evaluation revealed that the compounds of this invention have excellent inhibitory effects against methicillin-resistant Staphylococcus aureus strains, and all compounds exhibit certain antibacterial activity. This invention provides new ideas for the development of novel antibiotics. Attached Figure Description

[0029] Figure 1 For compound I-1 1 H NMR spectrum;

[0030] Figure 2 For compound I-1 13 C NMR spectrum;

[0031] Figure 3 For compound I-8 1 H NMR spectrum;

[0032] Figure 4 For compound I-8 13 C NMR spectrum;

[0033] Figure 5 This is a schematic diagram of sample loading in a 96-well plate in an application example. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments in order to better understand the technical solution.

[0035] Example 1: (3R,3'R,4'R,5'S)-1-benzyl-3'-chloro-3'-nitro-4'-phenyl-5'-(trifluoromethyl)spiro[indole-3,2'-pyrrolidine]-2-one

[0036]

[0037] At room temperature (25-30℃), (Z)-1-benzyl-3-(2,2,2-trifluoroethyl)imino)indol-2-one II (0.1 mmol, 1.0 eq.), dichloromethane (1 mL), and quinine aromatic amide derivative catalyst C1 (0.01 mmol, 0.1 eq.) were added to a 5 mL reaction tube and magnetically stirred for 5 minutes. After 10 minutes, nitroolefin III (0.15 mmol, 1.5 eq.) was added. The mixture was stirred at 25℃ for 3 hours. The reaction was detected by TLC with a petroleum ether:ethyl acetate ratio of 10:1 (v / v). The reaction solution was then subjected to direct silica gel column chromatography (eluent: petroleum ether:ethyl acetate = 30:1, v / v). The eluent with an Rf value of 0.2-0.4 was collected and evaporated to dryness under reduced pressure to obtain a white foamy product I-1 (90% yield, 97% ee, dr > 20:1). The 1H NMR spectrum is shown below. Figure 1 As shown, the carbon NMR spectrum is... Figure 2 As shown.

[0038] Product I-1 was determined by high performance liquid chromatography (3R,3'R,4'R,5'S)-1-benzyl-3'-chloro-3'-nitro-4'-phenyl-5'-(trifluoromethyl)spiro[indole-3,2'-pyrrolidine]-2-one, and the enantiomeric excess value was calculated.

[0039] High performance liquid chromatography was performed using Shimadzu HPLC (OD-H, IA, AD-H chiral columns). The mobile phase was V hexane / V isopropanol = 80:20-95:5, the flow rate was 1 mL / min, and the detection wavelength was 254 nm.

[0040] Example 2-28

[0041] Following a method similar to Example 1, only the R values ​​in the compounds shown in Formula I were replaced as shown in Table 1. Eluents with Rf values ​​of 0.2-0.4 were collected to obtain the corresponding compounds shown in Formula I. The 1H NMR spectra of products I-8 are shown below. Figure 3 As shown, the carbon NMR spectrum is... Figure 4 As shown, the 1H NMR spectra and high-resolution mass spectrometry data of the above compounds are listed in Table 1. It can be seen from the above that the structures of the above compounds are correct, and they are all compounds represented by Formula I.

[0042] Table 1 shows the proton NMR and high-resolution mass spectrometry data of the compounds represented by Formula I.

[0043]

[0044]

[0045]

[0046]

[0047]

[0048]

[0049]

[0050]

[0051]

[0052]

[0053]

[0054]

[0055] Application example: Application of chlorospirocyclic indolone compounds in the evaluation of antibacterial activity

[0056] 1. Study on the inhibitory activity of compound I against common bacteria (taking methicillin-resistant Staphylococcus aureus as an example).

[0057] 1) Cleaning of instruments: Wash and wrap test tubes, petri dishes, conical flasks, pipette tips and other experimental instruments, sterilize them at 121℃ for 20 minutes by autoclaving, and dry them in an oven for later use.

[0058] 2) Preparation of LB solid culture medium:

[0059] The composition of LB solid medium is: 10 g / L tryptone, 10 g / L sodium chloride, 5 g / L yeast extract, 15 g / L agar powder, and water as the solvent.

[0060] Weigh out 1g of tryptone, 0.5g of yeast extract, 1g of sodium chloride, and 1.5g of agar powder, and dissolve them in 100mL of pure water in a 250mL Erlenmeyer flask. Autoclave the prepared culture medium at 121℃ for 90 minutes. After the agar has cooled slightly, pour it into plates (15-20ml per plate) in a laminar flow hood. After solidification, incubate overnight at 37℃ for sterility testing. Once sterility is verified, store the plates in a laminar flow hood for later use.

[0061] 3) Preparation of LB liquid culture medium:

[0062] The composition of LB liquid culture medium is: yeast extract 5 g / L, tryptone 10 g / L, sodium chloride 10 g / L, and water as the solvent.

[0063] Dissolve 1g of tryptone, 1g of yeast extract, and 1g of sodium chloride in 100mL of pure water in a 250mL Erlenmeyer flask. Autoclave the prepared culture medium at 121℃ for 90 minutes. After slightly cooling, place it in a clean bench for later use.

[0064] 4) Preparation and preservation of the drug stock solution

[0065] Drug stock solution: The compounds prepared in Examples 1-28 were autoclaved and diluted with DMSO to a drug stock solution with a concentration of 12.8 mg / mL.

[0066] Positive control: 12.8 mg / mL ciprofloxacin in DMSO solution.

[0067] Blank control: DMSO.

[0068] 5) Preparation of bacterial solution

[0069] Methicillin-resistant Staphylococcus aureus (MRSA) was picked, streaked onto LB solid medium plates, and incubated at 37°C for 16–24 h. On the second day, a single colony was picked and inoculated into LB liquid medium and incubated at 37°C in a shaker for 16–24 h to obtain the test bacterial solution.

[0070] 2. Antibacterial rate determination

[0071] 1) Take 10 μl of the test bacterial solution and add it to an Erlenmeyer flask containing 100 ml of fresh LB liquid medium, and shake for 3 min;

[0072] 2) Using a pipette, pipette 199 μL of bacterial culture from the conical flask in step 1) and add it to all wells of the 96-well plate except for the outermost well (see...). Figure 5 Add 1 μl of DMSO to wells G7, G8, G9, G10, and G11 of a 96-well plate; add 1 μl of positive control solution (i.e., ciprofloxacin solution) to wells F7, F8, F9, F10, and F11 of the same 96-well plate. Repeat this process, adding 1 μl of different compound solutions to the remaining wells containing bacterial culture, grouping five wells together. The final drug concentration in each well is 64 μg / mL. After inspection, gently agitate and incubate at 37°C for 16-24 hours.

[0073] 3) Remove the 96-well plate, turn on the microplate reader, and measure the OD. 600 The inhibition rate was calculated, and the results are shown in Table 2. (Inhibition rate = (OD) 600 control-OD600 ) / OD 600 (control × 100%).

[0074] Table 2 shows the inhibition rate of the compounds represented by Formula I against bacteria (64 μg / mL).

[0075]

[0076]

[0077] The inhibition rate determination of the compounds shown in Formula I against bacteria revealed that these compounds exhibit good to excellent inhibitory activity against MRSA, demonstrating certain antibacterial activity. This further proves the significance of our developed asymmetric synthesis method for these compounds and expands the substrate adaptability range.

Claims

1. A chlorospirocyclic indole ketone compound, characterized in that, The structural formula of the compound is shown in formula (Ⅰ): (Ⅰ)。 2. The method for preparing a chlorospirocyclic indole ketone compound according to claim 1, characterized in that, The specific preparation method is as follows: In an air atmosphere, under the action of a solvent and a catalyst, the compound shown in formula (II) and the compound shown in formula (III) were reacted magnetically at 25-30℃ for 3 h. The reaction was monitored by TLC until it was complete. The reaction solution was then evaporated under reduced pressure until no liquid flowed out, yielding a yellow oily liquid. The yellow oily liquid was subjected to silica gel column chromatography with petroleum ether and ethyl acetate in a volume ratio of 30:1 as eluents. The eluent with an Rf value of 0.2-0.4 was collected and evaporated under reduced pressure to dryness, yielding a white foamy solid 3,2'-pyrrolidinyl-spirocyclic indole ketone compound shown in formula (I). The reaction formula is as follows: ； The catalyst is a quinine aromatic amide derivative C1: 。 3. The method for preparing a chlorospirocyclic indole ketone compound as described in claim 2, characterized in that, The molar ratio of the compound shown in formula (II) to the compound shown in formula (III) is 1:1-5; the molar ratio of the compound shown in formula (II) to the catalyst is 1:0.01-0.1; the volume of solvent used is 5-20 mL / mmol based on the amount of compound (II).

4. The use of the chlorospirocyclic indolone compound of claim 1 in the preparation of an antibacterial agent, wherein the antibacterial agent is an antibacterial agent against methoxycillin-resistant Staphylococcus aureus.

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