WO2024028533A1

WO2024028533A1 - 2-(pyrrolidin-1-yl)thiazole compounds and their use as antibiotic agents

Info

Publication number: WO2024028533A1
Application number: PCT/ES2023/070492
Authority: WO
Inventors: José Miguel SANSANO GIL; María de Gracia RETAMOSA HERNÁNDEZ; Francisco FOUBELO GARCÍA; Eduardo GARCÍA MINGÜENS; Juan Francisco ORTUÑO NAVARRO; H. Ali DÖNDAS; Samet POYRAZ; Naciye YAKTUBAY DÖNDAS; Mahmut ÜLGER; Samet BELVEREN
Original assignee: Universidad De Alicante; Cukurova University
Priority date: 2022-08-04
Filing date: 2023-07-31
Publication date: 2024-02-08
Also published as: ES2960818A1

Abstract

The present invention relates to compounds containing a 2-(pyrrolidin-1-yl)thiazole carbon backbone with a structure described in general formula (5). (5) Wherein R¹ = H, methyl, ethyl; R² = benzyl, (3-indolyl)methyl; R³ = 3-indolyl, aryl, phenyl; R⁴ = alkyl, cycloalkyl, phenyl, aryl, CO₂Me, SO₂Ph; R⁵ = CO₂Me, SO₂Ph, NO₂, COMe, etc., R⁴- R⁵ = -CO-NR-CO- (where this R = alkyl, cycloalkyl, phenyl, aryl), R⁶= -CO-aryl, -CO-phenyl, -CO-heteroaryl, -CO-3-cumaryl [2H-chromen-2-one)-3-yl] and R⁷ = aryl, phenyl, heteroaryl, 3-cumaryl [also referred to as 2H-chromen-2-one)-3-yl]. Another subject matter of the present invention is the formulations of the products of general formula (5) that are pharmaceutically acceptable for use as active species against different types of microorganisms, preferably for preventing and/or treating infections such as tuberculosis. The manufacturing method of said compound is also subject matter of the present invention.

Description

2-(Pyrrolidin-1-yl)thiazole compounds and their use as antibiotic agents.

TECHNIQUE SECTOR

The present invention relates to compounds with structures such as that described in general formula (5) and their pharmaceutically acceptable derivatives, where R ¹ = H, methyl, ethyl; R ² = benzyl, (3-indolyl)methyl; R ³ = 3-indolyl, aryl, phenyl; R ⁴ = alkyl, cycloalkyl, phenyl, aryl, CO ₂ Me, SO ₂ Ph; R ⁵ = CO ₂ Me, SO ₂ Ph, NO ₂ , COMe, etc., R ⁴ -R ⁵ = -CO-NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl), R ⁶ = - CO-aryl, -CO-phenyl, -CO-heteroaryl, -CO-3-coumaryl and R ⁷ = aryl, phenyl, heteroaryl, 3-coumaryl. These compounds can be used as active species against different types of resistant bacteria, preferably those that cause tuberculosis and other antibiotic-resistant bacteria.

Likewise, the present invention details the necessary steps (Schemes 1, 2 and 3) to transform the corresponding starting iminoester into polysubstituted pyrrolidines, which are treated with benzoyl isothiocyanate and, finally, the resulting product is subjected to a reaction with an alpha-bromoketone generating the final compounds of general formula (5).

In this way, the present invention, due to its wide field of application, is susceptible to being included both in the field of pharmaceutical chemistry and in that of medicine in general.

STATE OF THE PRIOR ART

In recent decades, the number of new antibiotics that have been marketed has progressively decreased. This negative evolution in the availability of therapeutic alternatives coincides with a progressive and generalized increase in resistance to antibiotics by microorganisms. The need for new antibiotics is something demanded by society and is one of the preferred lines of action by the World Health Organization. This patent drafting presents a new alternative family of antibiotics that may be interesting for the future. The structure of 2-(pyrrolidin-1 -yl)thiazole, and its respective carboxylic acid, have been synthesized by carrying out biological tests with results that are not very relevant. Initially, the structure of /V-benzoylaminocarbothioyl-pyrrolidine (precursor of the molecules or compounds object of this invention) was published in 2004 using a chiral menthyl acrylate in the preparation of the starting pyrrolidine (Heterocycl. Commun. 2004, 10, 167-173).

The biological activity of these intermediate compounds was evaluated as antibiotics and antifungals, obtaining quite low inhibition results (Turk. J. Chem. 2006, 30, 573-583), as well as that of their corresponding metal complexes of nickel(ll), palladium (ll), copper (ll) (Polyhedron 2009, 28, 2847-2854, Beilstein J. Org. Chem. 2021, 17, 2812-2821) and platinum (II) (Inorg. Chim. Acta 2019, 498, 1 19154). Furthermore, certain antitumor properties were observed when these intermediate molecules incorporated side chains derived from indole (Monats. Chem. 2018, 149, 2253-2263). This benzoylaminocarbothioyl unit was linked to pyrrolidino[3,4-b]pyrrolidine heterocyclic structures, which also exhibited weak to moderate antibacterial activity (Synthesis 2019, 51, 1565-1577).

Other applications of these precursor molecules consisted of the preparation of bicyclic thiohydantoins (Heterocycles, 2011, 83, 2091 -21 14; Monatsh. Chem. 2017, 148, 2173-2182)

In a first attempt, as soon as the synthesis of 2-(pyrrolidin-1 -yl)thiazoles was carried out, low antibiotic activity was observed (Tetrahedron 2017, 73, 6718-6727).

For all of the above, the applicant of the present patent detects the need to search for appropriate substituents in this type of skeletons that significantly increase the antibiotic power against bacteria resistant to conventional antibiotics.

DESCRIPTION OF THE INVENTION

Herein the term "pharmaceutically acceptable derivative" refers, for example, to a pharmaceutically acceptable ester, carboxylic acid or salt of a carboxylic acid.

The present invention refers, in a first aspect, to a series of molecules or compounds with a general formula (5), as well as to a pharmaceutical formulation acceptable comprising one of these compounds of general formula (5). Also the object of the present invention are the compounds of general formula (5) for use as an antibiotic agent and for use in the prevention and/or treatment of tuberculosis.

The skeleton of these structures (5) is made up of a pyrrolidine ring, also linked to a 1,3-thiazole unit through the two position of the latter, where the substituents can be alkyl, arylic, allylic, propargylic in nature. , benzylic, etc. These characteristics give the molecule greater preventive or curative activity, less degradation in the biological environment, which implies a greater therapeutic effect, as well as greater specificity towards antibiotic-resistant bacteria.

(5)

In the previous structure (5), acids or esters are generally represented (R ¹ = H, alkyl, respectively), R ² being an alkyl, allylic or methyleneheterocyclic substituent, etc. R ³ , R ⁴ and R ⁵ have alkyl, arylic, heterocyclic, allylic, propargylic, benzylic, etc. nature, while R ⁶ and R ⁷ can be aromatic, heteroaromatic, aliphatic, arenecarbonyl, heteroarenecarbonyl, etc. substituents.

From the group of molecules described above, and by way of example, the derivatives represented by the substituents R ¹ = methyl, ethyl; R ² = (3-indolyl)methyl, R ³ = 3-indolyl, 4-chlorophenyl; R ⁴ -R ⁵ = -CO-NR-CO-, R ⁶ = -CO-4-methoxyphenyl, -CO-3-coumaryl [2H-chromen-2-one)-3-yl], have great antibiotic activity measuring in vitro the IC ₅ o index of different resistant bacteria and, especially, against the bacteria that cause tuberculosis in humans (Table 1).

We should note that the -CO-3-coumaryl radical is also called 3-coumaryl, and it is also possible to refer to it as (2/-/-chromen-2-one)-3-yl. The synthesis of the molecules of the present invention (5) consists of three simple steps carried out under mild conditions.

The first intermediate product, that is, pyrrolidine or pyrrolidine derivative (3), is obtained by the reaction of iminoesters and electrophilic alkenes through a 1,3-dipolar reaction, generating azomethine ylides in situ at room temperature.

Secondly, a condensation reaction of the aforementioned pyrrolidines with benzoyl isothiocyanate is carried out, generating benzoylthiourea-pyrrolidines (4).

The last step leading to the final thiazol-pyrrolidine structure (5) consists of the addition of haloketones to the thioureas synthesized in the second reaction step.

DETAILED DESCRIPTION OF THE INVENTION

As mentioned above, the first step of the synthesis consists of the 1,3-dipolar addition between the iminoester (1) and the electrophilic alkene (2) in the presence of silver acetate in substoichiometric quantities and triethylamine, in toluene, and at room temperature (Scheme 1A) or in a reflux of toluene when R ⁴ -R ⁵ = -CO-NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl) (Scheme 1 B).

(this being R = alkyl, cycloalkyl, phenyl, aryl)

Scheme 1

The second condensation reaction step of pyrrolidines consists of a substitution on the nitrogen atom using benzoyl isothiocyante in acetonitrile at reflux for six hours or 24 h-36 h [in the latter case when R ⁴ -R ⁵ = -CO -NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl)] giving rise to the corresponding thiourea derivative (4) (Scheme 2A and 2B).

q, cycloalkyl, phenyl, aryl)

^4B )

Scheme 2

The last step of the synthetic process involves the intermediate molecules (4) and alpha-bromoketones (haloketones). For 24-48 hours at reflux of methanol or acetone, the addition of nucleophilic substitution by the sulfur atom is completed followed by the elimination of the benzoyl group and subsequent intramolecular condensation. The thiazoles (5) object of this patent were obtained in good yields and were purified by recrystallization or by column chromatography (Scheme 3).

Scheme 3

The present invention relates, therefore, to tlazoles with a pyrrolidine ring as a substituent and their acid derivatives, their synthesis and their applications as pharmaceutically acceptable formulations given their in vitro activity against different types of bacteria resistant to conventional antibiotics.

The known compounds (3 and 4) were prepared according to the procedure described in the literature [Inorganica Chimica Acta 2019, 498, 119154 and Monatshefte Für Chemie - Chemical Monthly 2017, 148, 2173-2182],

Examples

Example 1: Preparation of general compound (3) [R ¹ = H, methyl, ethyl; R ² = benzyl, (3- indolyl)methyl; R ³ = 3-indolyl, aryl, phenyl; R ⁴ = alkyl, cycloalkyl, phenyl, aryl, CÜ2Me, SO2PI1; R ⁵ = CO ₂ Me, SO2PI1, NO2, COMe, etc., R ⁴ -R ⁵ = -CO-NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl)].

Method A: A solution of Et ₃ N (1.7 mmol), Ag ₂ O (0.25 mmol) and mine (1) (1 mmol) in toluene (15 ml) was prepared. The dipolarophile solution (1 mmol) in toluene (10 ml) was then added dropwise. The reaction mixture was stirred at room temperature for 24 hours and the crude product was treated with saturated NaCl and NH ₄ CI, extracted with DCM and the phases Combined organics were dried over MgSO ₄ . The crude product was purified by column chromatography (EtOAc-Hexane, 1:2.5).

Method B: The corresponding maleimides (1 mmol) in toluene (10 mL) were added to a stirred solution of aldimine (1) (1 mmol) in toluene (15 mL). The resulting mixture was stirred at reflux for 36-48 h. The precipitated solid was then filtered and crystallized from Et ₂ O.

Example 2: Preparation of compound (4) [R ¹ = H, methyl, ethyl; R ² = benzyl, (3- indolyljmethyl; R ³ = 3-indolyl, aryl, phenyl; R ⁴ = alkyl, cycloalkyl, phenyl, aryl, CO ₂ Me, SO2PI1; R ⁵ = CO ₂ Me, SO2PI1, NO2 , COMe, etc., R ⁴ -R ⁵ = -CO-NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl)]

A solution of benzoyl isothiocyanate (1.2 mmol) in acetonitrile (5 ml) was added to the solution of pyrrolidine (3) (1 mmol) in acetonitrile (15 ml). The resulting mixture was heated at reflux for 6 or 24-36 hours. After completion of the reaction (monitored by TLC), the mixture crystallized from the reaction medium by slow evaporation. The precipitated yellow solid was filtered and purified by washing three times with Et ₂ O.

Example 3: Preparation of compounds (5) [R ¹ = H, methyl, ethyl; R ² = benzyl, (3- indolyljmethyl; R ³ = 3-indolyl, aryl, phenyl; R ⁴ = alkyl, cycloalkyl, phenyl, aryl, CO ₂ Me, SO2PI1; R ⁵ = CO ₂ Me, SO2PI1, NO2, COMe , etc., R ⁴ -R ⁵ = -CO-NR-CO- (this being R = alkyl, cycloalkyl, phenyl, aryl), R ⁶ = -CO-aryl, -CO-phenyl, -CO-heteroaryl, - CO-3-coumaryl [2H-chromen-2-one)-3-yl] and R ⁷ = aryl, phenyl, heteroaryl, 3-coumaryl]

The solution of a-bromoketone (1.4 mmol) in acetone or methanol (5 ml) was added to the solution of /V-benzoylaminocarbothiol (1 mmol) in acetone or methanol (25 ml). The resulting mixture was heated at reflux for 36-48 h. After completion of the reaction by TLC monitoring, the solvent was removed under reduced pressure. The mixture was extracted twice with NaCl/EtOAc and dried over MgSO ₄ . Purification of the mixture was carried out by column chromatography (Hexane/EtOAc, 2.5:1 v/v)

Example 4: In vitro efficacy studies of the compounds (5)

The cytotoxic activity of the molecules that describe the present invention was tested using different lines of microorganisms to establish their antimicrobial efficacy. The in vitro activity assay was carried out as detailed below:

Antibacterial test: the antibacterial activity of the mentioned compounds against Standard bacterial strains (Staphylococcus aureus [ATCC 25925], Bacillus subtilis [ATCC 6633], Aeromonas hydrophila [ATCC 95080], Escherichia coli [ATCC 25923], and Acinetobacter baumannii [ATCC 02026]) were determined with a resazurin microtiter assay (REMA). ). These standard strains were obtained from the Refik Saydam Hifzissihha Institute (Ankara, Türkiye). To obtain an initial concentration of 1000 pg/ml, the newly synthesized compounds were dissolved in DMSO to prepare stock solutions, and then, 0.22 pm membrane filters were used for sterilization of the compounds. Serial twofold dilutions of the compounds and ampicillin (standard reference drug) were prepared and the concentrations of the substances to be analyzed were adjusted to 500-0.24 pg/mL. All antibacterial activity determinations were repeated in duplicate.

Anti-tuberculosis assay: To determine the minimum inhibitory concentration (MIC) values of new compounds synthesized against the standard H37Rv strain of M. tuberculosis, the REMA method was used. The H37Rv standard strain was provided by the National Public Health Agency Refik Saydam, the National Tuberculosis Reference Laboratory (Ankara). Rifampicin (RIF) (Sigma R3501) and isoniazid (INH) (Sigma I3377) were used as reference drugs. To obtain an initial concentration of 1000 pg/mL, the stock solutions of the compounds were dissolved in DMSO. In a 96-well microtiter plate, a two-fold dilution series of the reference compounds and drugs was prepared in 100 μl of 7H9-S medium. 100 pL of the working solution of the standard strain H37Rv was added to the wells of the microtiter plates and then final concentration ranges of the compounds of 250-0.12 pg/mL were obtained. In each determination of anti-TB activity, a sterility control (without H37Rv working solution) and a growth control (without antibiotics) were included in each plate. The effects of DMSO were controlled by supplementing culture broth inoculated in the same solutions. Some of the most significant and important results of these antibacterial analyzes of the products (5) are detailed in Table 1. The exact structure of these molecules is established without ambiguity in Table 2. Table 1: MIC values (pg/mL) of the synthesized compounds (5) against anti(myco)bacterial strains.

Table 2: Substituents of the compounds (5) tested in Table 1

Considering the bioactivity results, the presence of the CH ₂ -3- indolyl group in the R ² position is notable. Modulation of this activity can be further achieved by alternating other substituents at all remaining positions. Thus, the bioactivity is greater when modifying the substituents in R ³ = 4-CI-C ₆ H ₄ - and R ⁶ = 3-coumaryl-CO-.

Claims

1. 2-(Pyrrolidin-1-yl)thiazole compounds of general formula (5)

in which:

R ¹ = H, methyl, ethyl;

R ² = benzyl, (3-indolyl)methyl;

R ³ = 3-indolyl, aryl, phenyl;

R ⁴ = alkyl, cycloalkyl, phenyl, aryl, CO ₂ Me, SO ₂ Ph; NO ₂ , COMe,

(this being R = alkyl, cycloalkyGy-phenyl, aryl);

R ⁶ = -CO-aryl, -CO-phenyl, -CO-heteroaryl, -CO-3-coumaryl

R ⁷ = aryl, phenyl, heteroaryl, -CO-3-coumaryl.

2. The compounds according to claim 1, wherein the pharmaceutically acceptable derivative is an ester, a carboxylic acid or a salt of a carboxylic acid.

3. A pharmaceutically acceptable formulation comprising a compound of formula (5) defined in claim 1.

4. Compounds of formula (5) defined in claim 1 for use as an antibiotic agent.

5. Compounds of formula (5) defined in claim 1 for use in the prevention and/or treatment of tuberculosis.