Thiapyran spiroindolone compounds and methods for their synthesis

Abstract

The present application belongs to the field of organic chemical synthesis, and particularly relates to a thiepany spiroindolone compound and a synthesis method thereof. The present application takes MBH ester derived from oxidized indole and alpha-alkenol dithioester as starting materials, and prepares the target compound through a two-step one-pot reaction at room temperature in a specific base and solvent system. The synthesis strategy is novel, the reaction condition is mild, the operation is simple, efficient, and easy to operate, the raw materials and solvents are easy to obtain and controllable in cost, the reaction selectivity is high, the product yield is considerable, the substrate application range is wide, and the functional group tolerance is strong. The target product has clear in-vitro anti-tumor activity, definite application prospect, and outstanding industrialization potential, provides a new scheme for the preparation of thiepany spiroindolone compounds, and has strong popularization value.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis, specifically relating to a thiarospiroindole ketone compound and its synthesis method. Background Technology

[0002] Thiaranspiroindole compounds are a key class of sulfur-containing heterocyclic compounds, with indole and thiaran rings as their core structures, possessing the unique characteristics of both hybrid skeletons and exhibiting potential biological activity. Among them, oxyindole, as an important skeleton for many natural products and drug molecules, has been proven to have broad biological activity, particularly in the anti-tumor field. It exerts anti-cancer effects through multiple pathways, such as regulating the cell cycle, inducing tumor cell apoptosis, and inhibiting angiogenesis, making it a superior skeleton for designing and synthesizing novel anti-tumor drugs. The thiaran ring, with its unique ring structure and electronic properties, endows compounds with good lipophilicity, biocompatibility, and targeted binding ability. Its derivatives have shown potential activity in antibacterial, anti-inflammatory, and anti-tumor activities, providing an important structural basis for the development of heterocyclic drugs.

[0003] Although oxyindole and thiaran ring each possess excellent biological activity potential, there are currently few reports on the synthetic methods and biological activity studies of thiaranspiroindole ketones constructed by combining the two through spirohybridization. Existing published literature and patents mainly focus on the synthesis and antitumor activity research of a few specific structures, such as: "Design, synthesis and biological evaluation of novel antitumor spirodihydrothiopyran-oxindole derivatives" (Bioorganic & Medicinal Chemistry Letters, 2019, 29, 1636-1640); "Synthesis of spiro-tetrahydrothiopyran-oxindoles by Michael-aldolcascade reactions: discovery of potential P53-MDM2 inhibitors with good antitumor activity" (Organic & Biomolecular Chemistry, 2018, 16(4), 625-634); "Design, synthesis and biological evaluation of novel antitumor spirotetrahydrothiopyran-oxindole derivatives as potent p53-MDM2 inhibitors" (Bioorganic & Medicinal Chemistry, 2017, 25). (Patent No.: CN107235991) The above studies confirmed that thiazolinone compounds have in vitro anticancer activity against three types of human cancer cells carrying the normally functioning p53 protein: A549 lung cancer cells, HCT116 colon cancer cells, and MDA-MB-231 breast cancer cells.Core test results showed that most of these derivatives exhibited moderate to good inhibitory effects on all tested cancer cells. Target and mechanism studies revealed that these compounds exert their anti-tumor effects by preventing the binding of p53 to MDM2 proteins, with clearly defined targets and some compounds showing excellent binding affinity to MDM2. Further Western blotting confirmed that these compounds, similar to the classic MDM2 inhibitor nutlin-3, dose-dependently upregulate the expression levels of p53 and MDM2 proteins in A549 cells. Molecular docking analysis identified the binding sites of the compounds to the MDM2 protein, specifically the three key hotspot regions: Leu26, Phe19, and Trp23. These findings lay an important foundation for the further development and application of thiaspiroindole compounds and provide a clear direction for the subsequent design of this invention. Summary of the Invention

[0004] This invention provides a synthetic method for obtaining thiaspiroindole ketones. This method uses MBH esters derived from indole oxide and α-enol dithioesters as starting materials, with dichloromethane or chloroform as solvents. After the starting materials have completely reacted in the presence of a base, another base is added to the reaction system to induce an isomerization reaction. The two-step one-pot method is carried out at room temperature, which can simply and efficiently synthesize thiaspiroindole ketones.

[0005] The specific technical solution of the present invention is as follows:

[0006] One of the technical solutions of this invention is to provide a thiaspiroindolone compound, the structural formula of which is shown in Formula I:

[0007]

[0008] Formula I

[0009] in:

[0010] R¹ is selected from alkyl groups, including methyl, allyl, or benzyl;

[0011] R² is selected from methyl, methoxy, halogen, nitro or ester group, and its substitution position is located at the 4-, 5-, 6- or 7-position of the indoleone ring;

[0012] R³ is selected from ester or cyano groups;

[0013] R 4 The group is selected from alkyl, substituted phenyl, naphthyl or heteroaryl, wherein the alkyl group includes methyl, cyclopropyl, isopropyl or isobutyl, the substituted phenyl group is substituted with halogen, methyl, methoxy, ester or cyano, and the heteroaryl group includes furanyl, thiophene or pyridyl.

[0014] R 5It is selected from alkyl groups, including allyl, benzyl, methyl, ethyl, or tert-butyl.

[0015] The second technical solution of the present invention provides a method for synthesizing thiaspiroindolone compounds, wherein the synthetic reaction formula of the thiaspiroindolone compounds is shown in Formula II:

[0016]

[0017] Formula II

[0018] The method for synthesizing thiaspiroindolone compounds includes the following steps:

[0019] Compound II and compound III are reacted in a solvent in the presence of base A;

[0020] After compound II has reacted completely, base B is added to the reaction system to continue the reaction;

[0021] After the reaction is complete, the reaction mixture is post-treated to obtain the thiaspiroindolone compound represented by Formula I;

[0022] Compound II is an MBH ester derived from indole oxide, and compound III is an α-enol dithioester.

[0023] As a further option for the synthesis method of the present invention, the solvent is selected from one or more of toluene, acetonitrile, 1,4-dioxane, 1,2-dichloroethane, acetone, dichloromethane, ethyl acetate, ethanol, chloroform, N,N-dimethylformamide, tetrahydrofuran, and chloroform.

[0024] As a further option for the synthesis method of the present invention, the base A is the Lewis base 1,4-diazabicyclo[2.2.2]octane.

[0025] As a further option for the synthesis method of the present invention, the base B is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), cesium carbonate, 1,5-diazabicyclo[4.3.0]non-5-ene, tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

[0026] As a further option for the synthesis method of the present invention, the molar ratio of compound II to compound III is 1:1 to 1:2, the amount of base A is at least 0.1 equivalents, and the amount of base B is at least 0.5 equivalents.

[0027] As a further option of the synthesis method of the present invention, the post-processing includes:

[0028] The organic solvent was removed from the reaction mixture under reduced pressure to obtain the crude product;

[0029] The crude product was purified by silica gel column chromatography. The eluent used for silica gel column chromatography was a mixed solvent of petroleum ether and ethyl acetate, wherein the volume ratio of petroleum ether to ethyl acetate was 40:1 to 5:1.

[0030] The beneficial effects of the technical solutions provided in this application include at least the following:

[0031] This invention pioneers a synthetic route for constructing thiaspiroindole ketones using MBH esters derived from indole oxide and α-enol dithioesters as starting materials via a two-step, one-pot method. This strategy overcomes the limitations of existing synthetic methods, efficiently integrating the construction of two key heterocyclic skeletons. Such synthetic approaches have not been previously reported in the literature, providing a novel preparation scheme for this class of compounds with potential pharmaceutical value and enriching the technical system for heterocyclic compound synthesis.

[0032] The entire reaction is conducted at room temperature, eliminating the need for harsh reaction conditions such as high temperatures and metal catalysis, thus reducing equipment requirements and operational risks. The two-step reaction is completed continuously in the same system, eliminating the need to separate intermediates and reducing operational steps and material losses. The post-processing is simple, requiring only solvent removal through vacuum concentration followed by silica gel column chromatography to obtain high-purity products, significantly improving synthesis efficiency and facilitating large-scale laboratory preparation and subsequent industrial applications.

[0033] The starting materials, indole-derived MBH esters and α-enol dithioesters, are common intermediates in organic synthesis, with low preparation difficulty, abundant market supply, and controllable procurement costs. The solvents used in the reaction are conventional organic solvents such as dichloromethane, chloroform, and tetrahydrofuran; the catalysts selected are Lewis base DABCO and various common organic / inorganic bases, avoiding the use of precious metal catalysts, significantly reducing synthesis costs, and improving the economics and promotional value of the technology.

[0034] The reaction system achieves highly selective reactions by precisely controlling the molar ratio of raw materials and the type and amount of alkali. The amount of byproducts generated during the process is extremely small, and the separation and purification of the target product is easy. Experimental verification shows that the product yield can reach over 84%, with some examples achieving a yield of 72%, far exceeding the yield levels of existing similar synthetic methods, ensuring the high efficiency and practicality of the synthesis process.

[0035] The target products, thiaspiroindole compounds, have been proven to possess significant in vitro antitumor activity, inhibiting various cancer cells such as A549 lung cancer cells and HCT116 colon cancer cells. Their specific targets provide a high-quality scaffold structure for the development of novel antitumor drugs. The efficient synthesis method of this invention can stably supply these compounds, meeting the needs of pharmaceutical research and development, bioactivity testing, and other fields. Furthermore, the mild reaction conditions, low cost, and simple operation process lay a solid foundation for subsequent industrialization, demonstrating outstanding practical value and market potential. Attached Figure Description

[0036] Figure 1 The nuclear magnetic resonance (H1N) spectrum of product I-1 obtained in the embodiment of the present invention is shown.

[0037] Figure 2 The image shows the nuclear magnetic resonance (carbon) spectrum of product I-1 obtained in the embodiments of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0039] The following are preferred embodiments for the preparation of compounds according to the present invention. In all the following embodiments, NMR detection was obtained primarily by nuclear magnetic resonance in CDCl3. δ values ​​were obtained as internal standard relative values ​​using a 4G quadrupole time-of-flight mass spectrometer.

[0040] Indigo-derived MBH carbonate, designated Reagent II, was used at a volume of 0.2 mmol; α-enol dithioester, designated Reagent III, was used at a volume of 0.24 mmol; 1,4-diazabicyclo[2.2.2]octane, designated DABCO, was used at a volume of 6.7 mg; and chloroform was used at a volume of 2.0 mL as the reaction solvent. Separately, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, designated MTBD, was prepared; the eluent was a mixture of petroleum ether (PE) and ethyl acetate (EtOAc), prepared in a volume ratio gradient from 10:1 to 3:1, for column chromatography purification.

[0041] Add reagents II, III, and DABCO sequentially to a 25 mL transparent glass reaction flask equipped with a magnetic stir bar. Finally, add chloroform as a solvent and gently shake the flask to initially mix the reagents. Place the reaction flask at room temperature, turn on the magnetic stirrer, and control the stirring rate to ensure uniform mixing of the reaction system. Continue stirring for 4-10 hours. During stirring, monitor the reaction progress in real time using thin-layer chromatography (TLC), using the consumption of reagents as the criterion. When TLC shows that the reagents are completely consumed, stop the first step of the reaction; at this point, an intermediate is formed in the reaction system.

[0042] In the reaction system containing the intermediate, MTBD solution is slowly added while maintaining the reaction system at room temperature during the addition process to avoid drastic local temperature changes or solvent evaporation caused by reagent addition. Magnetic stirring is continued at room temperature for 4-8 hours; the consumption of the intermediate is monitored by TLC. When TLC shows that the intermediate has been completely consumed, the second step of the reaction is stopped.

[0043] After stirring is stopped, without quenching, the entire reaction system is directly transferred to a rotary evaporator for concentration under vacuum to remove the organic solvent and obtain a crude product residue. The crude product residue is then purified by silica gel column chromatography. The residue is uniformly loaded onto the top of a silica gel column, and a mixture of petroleum ether and ethyl acetate with a volume ratio of 10:1 to 3:1 is used as the eluent. Elution is performed slowly in a gradient manner, initially at 10:1 and gradually adjusted to 3:1. The eluent composition is monitored by TLC, and the eluent fraction containing target product I is collected. The collected fraction is concentrated under vacuum to remove the eluent, finally yielding pure target product I. The structural formula of product I is shown below:

[0044]

[0045] Methyl 5'-benzoyl-1-methyl-6'-(methylthio)-2-oxospiro[indoline-3,2'-thiopyran]-3'-carboxylate. Compound I-1 (94 mg, Yield = 72%, R f = 0.30 (PE / EA = 3:1)) was isolated as a yellow solid; mp 157−158 o C. 1H NMR (500 MHz, CDCl3) δ 7.85–7.81 (m, 2H), 7.66 (s, 1H), 7.59–7.55 (m, 1H), 7.50 (t, J = 7.5Hz, 2H), 7.40 (d, J = 7.5 Hz, 1H), 7.38 (td, J = 7.5, 1.0 Hz, 1H), 7.08 (t, J= 7.5 Hz, 1H), 6.91 (d, J = 7.8 Hz, 1H), 3.55 (s, 3H), 3.33 (s, 3H), 2.43 (s,3H); 13 C NMR (125 MHz, CDCl3) δ 191.8, 175.1, 165.0, 158.5, 141.8, 138.0,137.7, 132.6, 131.7, 130.5, 129.5, 128.7, 124.8, 124.0, 123.6, 115.5, 108.9,54.2, 52.3, 27.2, 17.7; ESI-HRMS m / z calcd for C 23 H 20 NO4S2 [M + H] + 438.0828, found 438.0829.

[0046] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0047] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be carried out within the widest scope consistent with the principles and novel features of the invention herein.

[0048] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A thiaspiroindolone compound, characterized in that, The structural formulas of thiamethoxam-indolone compounds are shown in Formula I: Formula I in: R¹ is selected from alkyl groups, including methyl, allyl, or benzyl; R² is selected from methyl, methoxy, halogen, nitro or ester group, and its substitution position is located at the 4-, 5-, 6- or 7-position of the indoleone ring; R³ is selected from ester or cyano groups; R 4 The group is selected from alkyl, substituted phenyl, naphthyl or heteroaryl, wherein the alkyl group includes methyl, cyclopropyl, isopropyl or isobutyl, the substituted phenyl group is substituted with halogen, methyl, methoxy, ester or cyano, and the heteroaryl group includes furanyl, thiophene or pyridyl; R 5 It is selected from alkyl groups, including allyl, benzyl, methyl, ethyl, or tert-butyl.

2. A method for synthesizing thiaspiroindole ketone compounds as described in claim 1, characterized in that, The synthetic reaction formula for the thiaspiroindolone compounds is shown in Formula II: Formula II The method for synthesizing thiaspiroindolone compounds includes the following steps: Compound II and compound III are reacted in a solvent in the presence of base A; After compound II has reacted completely, base B is added to the reaction system to continue the reaction; After the reaction is complete, the reaction mixture is post-treated to obtain the thiaspiroindolone compound represented by Formula I; Compound II is an MBH ester derived from indole oxide, and compound III is an α-enol dithioester.

3. The synthesis method according to claim 2, characterized in that, The solvent is selected from one or more of toluene, acetonitrile, 1,4-dioxane, 1,2-dichloroethane, acetone, dichloromethane, ethyl acetate, ethanol, chloroform, N,N-dimethylformamide, tetrahydrofuran, and chloroform.

4. The synthesis method according to claim 2, characterized in that, The base A is the Lewis base 1,4-diazabicyclo[2.2.2]octane.

5. The synthesis method according to claim 2, characterized in that, The base B is selected from one or more of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), cesium carbonate, 1,5-diazabicyclo[4.3.0]non-5-ene, tetramethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, or 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene.

6. The synthesis method according to claim 2, characterized in that, The molar ratio of compound II to compound III is 1:1 to 1:2, the amount of base A is at least 0.1 equivalents, and the amount of base B is at least 0.5 equivalents.

7. The synthesis method according to claim 2, characterized in that, The post-processing includes: The organic solvent was removed from the reaction mixture under reduced pressure to obtain the crude product; The crude product was purified by silica gel column chromatography. The eluent used for silica gel column chromatography was a mixed solvent of petroleum ether and ethyl acetate, wherein the volume ratio of petroleum ether to ethyl acetate was 40:1 to 5:1.

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