Search

The study shows that traditional methods for synthesizing ortho-carboranes from nido-B₁₀H₁₄ and its complexes (B₁₀H₁₂L₂) using donor- and acceptor-disubstituted acetylenes yielding low efficiencies (yields 0 - 12%). Attempts to improve yields with ionic liquids and silver salts as catalysts were unsuccessful with disubstituted acetylenes. However, it has been found that the use of mono-substituted acetylenes (phenylacetylene, ethyl propiolate) in the presence of silver salts in the reaction with B₁₀H₁₂L₂ substrates produces ortho-carboranes in high yields (~90%). This suggests that the key step is the formation and subsequent addition of silver acetylenides, and not the donor-acceptor π-complexes previously assumed. This finding allows us to better understand the mechanisms of the ortho-carboranes formation and offers an efficient pathway for their synthesis.

Inspired by the bioactivity of natural compounds with a bicyclo[3.3.0]octane core, the study focuses on developing tetrahydropentalene-2,5-dione (2,5-THP-dione) derivatives as potential building blocks for the use in medicinal chemistry. Using the commercially available 2,5-THP-dione, a number of alkylated derivatives and a monofunctional ketone were synthesized. Using optimized protocols for synthesis, target compounds were obtained with high yields on a multigram scale. These compounds are promising derivatives for further chemical derivatization and therapeutic use, and thus highlight the value of 2,5-THP-dione in creating complex molecular structures for drug discovery, as well as the importance of tetrahydropentalene derivatives as valuable building blocks in synthetic chemistry.

Aim. To synthesize new fluoro-containing building blocks for medicinal chemistry purposes using electrophilic reactions of 7-(trifluoromethyl)-2,3-dihydro-1H-pyrrolizine.
Results and discussion. Synthetic approaches to 5-halogeno- and 5-acyl-7-(trifluoromethyl)-2,3-dihydro-1H-pyrrolizines have been developed. The obtained new trifluoromethyl-containing pyrrolyzines are promising building blocks for medicinal chemistry.
Experimental part. The synthesis of the target compounds began with known 7-(trifluoromethyl)-2,3-dihydro-1H-pyrrolizine and included halogenation and acylation reactions using N-halogen succinimides and acylating reagents.
Conclusions. New synthetic approaches to a number of 7-(trifluoromethyl)-2,3-dihydro-1H-pyrrolizines with various substituents, such as halogen atoms or acyl groups, at the position 5 of the pyrrole ring have been developed. This opens the door to the use of such promising trifluoromethyl-containing building blocks for medicinal chemistry needs.

The efficient and scalable synthesis of homoallylic amines is a subject of significant interest due to the potential applications of these compounds in medicinal and synthetic chemistry. The three-component Petasis reaction is an excellent approach for obtaining these compounds. Based on previous studies, this work explores the α-aminoallylation of ketones and aldehydes using allylboronic acid pinacol ester. Compared to classical methods, the protocol developed reduces the excess of reagents, increasing the environmental friendliness of the process, while maintaining high yields. A wide range of substrates, including various aliphatic, cyclic, and heterocyclic ketones, was studied to identify factors affecting the reactivity. The method was also successfully applied to aldehydes, producing amine-containing building blocks on a large scale. Various work-up procedures were optimized for efficient isolation of the homoallylamines synthesized without the need for chromatographic purification.

Aim. To develop a preparative method for the synthesis of N-trimethylsilylimine of trifluoropyruvate, and study its interaction with acetone under organocatalytic conditions.
Results and discussion. A simple preparative approach to the first representative of N-silylimines of trifluoropyruvate was developed based on the interaction of triphenylphosphinimide and trifluoropyruvic acid methyl ester by the aza-Wittig reaction. It was found that the addition of acetone to N-silylimine occurred in the presence of L- or D-proline and led to the formation of enantiomerically enriched α-amino-γ-oxocarboxylates. The hydrolysis of the ester function resulted in (R)-α-trifluoromethyl aminocarboxylic acid, and the cyclocondensation with isocyanates or 2,5-dimethoxytetrahydrofuran yielded nitrogen-containing heterocycles containing pyrimidine or pyrrolizine nuclei.
Experimental part. The synthetic procedures for the N-silylimine of trifluoropyruvate and its reaction with acetone are provided, along with the transformations of obtained α-amino-γ-oxocarboxylates (hydrolysis, cyclocondensations with isocyanates and 2,5-dimethoxytetrahydrofuran). The structures of the compounds synthesized were proven by ¹H, ¹³C, ¹⁹F NMR spectroscopy methods, as well as by the elemental analysis.
Conclusions. A convenient method for the synthesis of N-silylimine of trifluoropyruvate has been developed. Using the example of the Mannich reaction with acetone, it has been demonstrated that N-silylimine of trifluoropyruvate is a convenient substrate for the synthesis of optically active 3,3,3-trifluoroalanine derivatives.

The article describes a set of pyridines annulated with functionalized 6-membered saturated rings, which are attractive building blocks for the synthesis of diversified compound libraries in medical chemistry. A certain array of compounds includes pyridines with condensed cyclohexane, piperidine and tetrahydropyran cycles containing keto-, amino-, carboxylic groups, as well as fluorinated fragments. The synthesis of the compounds using the procedure previously developed by us via CuCl₂-catalyzed condensation of propargylamine with ketones was performed. The limits of application of this reaction were further expanded and determined in this work compared to our previous results. Condensed pyridines, which proved problematic or impossible to obtain by this method, were synthesized using other synthetic pathways. Thus, the study offers a number of new building blocks for use in drug discovery.

Developing efficient and scalable synthetic protocols for key polymer precursors is crucial to advancing high-performance materials designed to withstand severe thermal environments. In this article, we report on the development of solid, high-yield methods for preparing structurally diverse building blocks, including s-triazine derivatives, phenyl-borosilane alkynyl oligomers, phthalonitrile-based monomers, and novel diamine curing agents on multi-gram to multi-hundred-gram scales. These carefully optimized procedures use readily available starting materials, mild conditions, and well-known synthetic transformations, thus addressing the longstanding challenges associated with their practical upscaling. The resulting library of monomers and oligomers offers a broad range of reactive functional groups (e.g., nitriles, alkynes, borosilane motifs), enabling future combinatorial-like strategies for the formation of advanced co-polymers with enhanced thermal stability, mechanical strength, and tunable properties suitable for high-temperature applications.

During the last decade, national and foreign scientists have been constantly examining an example of studying the physicochemical and biological properties of nitrogen containing heterocycles, particularly with the nucleus of 1,2,4-triazole. The main advantage of such substances is to exhibit low levels of acute toxicity with a wide spectrum of pharmacological activity. To date, a large number of medicines on the basis of 1,2,4-triazole has been created, namely fluconazole, voriconazole, anastrozole, itraconazole, and letrozole. Therefore, the creation of new molecules based on 1,2,4-triazole and the search for new biologically active compounds among them is an urgent task of modern synthetic and pharmaceutical chemistry.

Aim. To study some aspects of 5-phenethyl-1H-1,2,4-triazole-3-amine reactivity and investigate the physicochemical properties of synthesized compounds.

Results and discussion. A series of 1-alkyl(aryl)-N-(5-phenethyl-1H-1,2,4-triazolе-3-yl)methanimines has been synthesized and the reaction of their reduction has been studied. The structure and purity of the synthesized compounds have been confirmed by the complex of modern instrumental methods of analysis – elemental analysis, IR, ¹H NMR spectroscopy, LC-MS.

Experimental part. The reaction of 5-phenethyl-1H-1,2,4-triazole-3-amine with aldehydes at the ambient temperature in acetic acid medium gave 1-alkyl(aryl)-N-(5-phenethyl-1H-1,2,4-triazolе-3-yl)methanimines. At the next stage, the selective reduction of the exocyclic C=N-group of 1-alkyl(aryl)-N-(5-phenethyl-1H-1,2,4-triazolе-3-yl)methanimines by the action of sodium borohydride in the dimethylformamide was carried out.

Conclusions. 13 new 1,2,4-triazole derivatives, namely 1-alkyl(aryl)-N-(5-phenethyl-1H-1,2,4-triazolе-3-yl)methanimines and arylmethyl-(5-phenethyl-1H-1,2,4-triazolе-3-yl)amines, have been obtained. The both structure and purity of the obtained substances have been confirmed by the complex of modern instrumental methods of analysis.

Received: 12.08.2019
Revised: 18.09.2019
Received after correction: 27.12.2019
Revised: 25.04.2020
Accepted: 29.05.2020

Aim. To conduct the synthesis and confirm the structure of 3-methyl-6-R-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole derivatives as potential biologically active compounds.

Results and discussion. It has been shown that the heterocyclization reaction of 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol with carboxylic acids in the excess of phosphorus oxychloride yields 3-methyl-6-R-[1,2,4]-triazolo[3,4-b][1,3,4]thiadiazoles.

Experimental part. The reaction of 4-amino-5-methyl-4H-1,2,4-triazole-3-thiol with the corresponding carboxylic acids was carried out in the excess of phosphorus oxychloride. The mixture was heated for 5 h with subsequent cooling and neutralization to pH 7 using ammonia solution. ¹H NMR spectra of the compounds synthesized were recorded on a Varian Mercury VX-200 spectrometer operating at a frequency of 200 MHz, in DMSO-d₆, using tetramethylsilane (TMS) as an internal standard. Melting points were measured using a MPA100 device. The elemental analysis was performed on a Elementar Vario EL Cube elemental analyzer. Agilent 1260 Infinity HPLC System equipped with Agilent 6120 mass spectrometer were used for registering LC-MS data.

Received: 18.02.2020
Revised: 29.04.2020
Accepted: 29.05.2020

Aim. To develop the preparative method for the synthesis of optically active α-amino-α-polyfluoroalkyl-γ-oxobutylphosphonic acids as new promising chiral building blocks.
Results and discussion. It has been shown that the reaction of NH-polyfluoroalkyl aminophosphonates with acetone in the presence of a catalytic amount of L- or D-proline occurs stereoselectively to give enantiomerically enriched (R)- or (S)-α-amino-γ-oxophosphonates, respectively. The resulting optically active phosphonates were converted into water-soluble α-amino-γ-oxophosphonic acids isolated in the individual form as hydrochlorides.
Experimental part. By the reaction of рolyfluoroacetonitriles with diethyl phosphite in the presence of triethylamine the series of NH-рolyfluoroalkyl іminophosphonates were synthesized. They undergo the prolinecatalysed reaction with acetone to form optically active α-amino-α-polyfluoroalkyl-γ-oxobutyl phosphonates. The latter were converted into the corresponding phosphonic acids by the reaction with hydrogen chloride. The structures of the compounds synthesized were confirmed by analytical and spectral NMR (1Н, 13С, 19F, 31Р) methods.
Conclusions. Based on the proline-catalyzed reaction of NH-рolyfluoroalkyl іminophosphonates with acetone the preparative
synthesis method for new chiral building blocks – α-amino-α-polyfluoroalkyl-γ-oxobuthylphosphonates and phosphonic acids has been developed.

The treatment of infectious diseases is one of the global problems of modern medicine. Despite the large amount of medications the problem of creation of new highly effective antimicrobials is a relevant task. This is, mainly, due to the increase of microbial resistance to the widely used antimicrobials. One of the promising ways to solve this task is the search and creation of new antimicrobial substances.

Aim. To search for the substances with the antimicrobial activity among derivatives of morpholine-containing 2-R-phenyliminothiazole, namely N-[4-methyl-2-(R-phenylimino)thiazol-3-yl]-morpholine derivatives.

Results and discussion. The results of the biological screening demonstrated that all compounds studied in the concentration of 1 % revealed the antibacterial and antifungal effect. It was determined that the compounds had the most pronounced antibacterial effect on gram-positive strains of microorganisms (with the average diameter of the inhibition zones of 23-27 mm) and a little less effect on gram-negative strains of microorganisms (with the average diameter of the inhibition zones of 15-25 mm). Compound 3c – N-[4-methyl-2-(2’,5’-dimethylphenylimino)thiazol-3-yl]morpholine hydrochloride showed the highest activity against all strains of microorganisms tested.

Experimental part. The biological screening for the antimicrobial activity was carried out in vitro by the agar diffusion method (“wells” method).

Conclusions. It has been found that N-[4-methyl-2-(R-phenylimino)thiazol-3-yl]-morpholine derivatives can be promising objects for further in-depth studies of the antimicrobial activity and for creating new effective antimicrobial drugs.

It is known that carboxyl groups bonded to aryl or hetaryl moieties play a role of the “pharmacophore” fragment in most NSAID molecules. It should be mentioned that the carboxyl group may cause the appearance of toxic effects and is characterized by unsatisfactory pharmacokinetic properties. The structural modification of the carboxyl group, including its bioisosteric replacement, is among the most widely used approaches in medicinal chemistry to improve pharmacodynamic, pharmacokinetic and technological characteristics.

Aim. To develop the synthetic procedures for functional derivatives of 3-R-2,8-dioxo-7,8-dihydro-2Н-pyrrolo[1,2-а][1,2,4]triazino[2,3-с]quinazoline-5а(6Н)-carboxylic(-propanoic) acids, study the effect of the carboxyl group chemical modification on the LOX-inhibiting and antiradical activity as a possible mechanism of the pharmacological activity.

Results and discussion. The synthesis of esters of 3-(2,8-dioxo-3-R¹-7,8-dihydro-2H-pyrrolo[1,2-a][1,2,4]triazino[2,3-c]quinazolin-5a(6H)-yl)carboxylic(propanoic) acids was conducted by esterification of the corresponding acids and tandem heterocyclization of 2-(6-R¹-2,5-dihydro-5-оxo-1,2,4-triazino-3-yl)anilines with diethyl 4-oxoheptanedioate. The synthesis of amides was conducted by aminolysis of N-acylimidazolides generated in situ. The antiradical and LOX-inhibiting activities of the compounds obtained were studied as possible mechanisms of the anti-inflammatory activity. The series of the compounds revealed the LOX-inhibiting activity that was comparable with the effect of the reference compound – nordihydroguaiaretic acid.

Experimental part. The synthetic procedures were conducted according to the commonly used methods. The purity and the structure of the compounds obtained were proven by modern physicochemical methods (¹H and ¹³C NMR-spectroscopy, LC-MS-spectrometry). The antiradical activity was measured by the ability to scavenge a DPPH-radical. The study of the LOX-inhibiting activity was performed using soybean LOX as an enzyme and linolenic acid as a substrate.

Conclusions. The methods for the synthesis of esters and amides of 2,8-dioxo-3-R¹-7,8-dihydro-2H-pyrrolo[1,2-a][1,2,4]triazino[2,3-c]quinazolin-5a(6H)-carboxilic(propanoic) acids have been developed. The abovementioned transformations were conducted by alcoholysis of generated in situ acyl halides and aminolysis of N-acylimidazolides, respectively. The more efficient approach for the synthesis of the target esters via condensation of 2-(6-R¹-2,5-dihydro-5-oxo-1,2,4-triazino-3-yl)anilines with diethyl 4-oxoheptanedioate has been proposed. It has been found that the highest radical scavenging and LOX-inhibiting activities are characteristic for hetarylpropanoic acids that contain electron withdrawing substituents in position 3, as well as fluorine atoms in positions 11 and 12. The chemical modification of the carboxylic group in most cases results in a decrease or the loss of the activity.

Received: 10.01.2019
Revised: 04.02.2020
Accepted: 27.02.2020