Iodine-Catalyzed Radical C-H Amination of Nonaromatic Imidazole Oxides: Access to Cyclic α-Aminonitrones

A straightforward cross-dehydrogenative coupling approach to incorporate alicyclic amino residues into the structure of model cyclic aldonitrones, 2H-imidazole oxides, is reported. The elaborated C(sp2)-H functionalization is achieved by employing cyclic amines in the presence of the I2-tert-butyl hydroperoxide (TBHP) reagent system. As a result, a series of 19 novel heterocyclic derivatives were obtained in yields of up to 97%. A mechanistic study involving electron paramagnetic resonance spectroscopic experiments allowed the radical nature of the reaction to be confirmed. In particular, the envisioned mechanistic rationale comprises N-iodination of a cyclic amine, followed by N-I bond homolysis of the resulting intermediate and subsequent amination of the nitrone moiety via the newly generated nitrogen-centered radical.

Derivatives of 9-phosphorylated acridine as butyrylcholinesterase inhibitors with antioxidant activity and the ability to inhibit β-amyloid self-aggregation: potential therapeutic agents for Alzheimer's disease

We investigated the inhibitory activities of novel 9-phosphoryl-9,10-dihydroacridines and 9-phosphorylacridines against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and carboxylesterase (CES). We also studied the abilities of the new compounds to interfere with the self-aggregation of β-amyloid (Aβ42) in the thioflavin test as well as their antioxidant activities in the ABTS and FRAP assays. We used molecular docking, molecular dynamics simulations, and quantum-chemical calculations to explain experimental results. All new compounds weakly inhibited AChE and off-target CES. Dihydroacridines with aryl substituents in the phosphoryl moiety inhibited BChE; the most active were the dibenzyloxy derivative 1d and its diphenethyl bioisostere 1e (IC50 = 2.90 ± 0.23 µM and 3.22 ± 0.25 µM, respectively). Only one acridine, 2d, an analog of dihydroacridine, 1d, was an effective BChE inhibitor (IC50 = 6.90 ± 0.55 μM), consistent with docking results. Dihydroacridines inhibited Aβ42 self-aggregation; 1d and 1e were the most active (58.9% ± 4.7% and 46.9% ± 4.2%, respectively). All dihydroacridines 1 demonstrated high ABTS•+-scavenging and iron-reducing activities comparable to Trolox, but acridines 2 were almost inactive. Observed features were well explained by quantum-chemical calculations. ADMET parameters calculated for all compounds predicted favorable intestinal absorption, good blood-brain barrier permeability, and low cardiac toxicity. Overall, the best results were obtained for two dihydroacridine derivatives 1d and 1e with dibenzyloxy and diphenethyl substituents in the phosphoryl moiety. These compounds displayed high inhibition of BChE activity and Aβ42 self-aggregation, high antioxidant activity, and favorable predicted ADMET profiles. Therefore, we consider 1d and 1e as lead compounds for further in-depth studies as potential anti-AD preparations.

Approbation of a New Model of Secondary Damage after Traumatic Brain Injury Based on Reprogrammed Rat Embryo Fibroblasts

The paper presents a new model of secondary injuries after traumatic brain injury. The model is based on the cultivation of rat embryonic fibroblasts reprogrammed to a neuronal phenotype in the presence of cerebrospinal fluid from injured rats. The presented model was used to test the therapeutic effect of inducers of the synthesis of chaperones from the classes of pyrrolylazines and indolylazines, which have neuroprotective properties.

Mesomeric Betaines Based on Adamantylated 1,2,4-Triazolo[4,3-a]pyrimidin-5-ones: Synthesis, Structure and Conversion into Anionic N-Heterocyclic Carbenes

The C-N coupling of 1,2,4-triazolo[1,5-a]pyrimidin-7-ones with 1-adamantanol/1-bromoadamantane leads to 1,2,4-triazolo[4,3-a]pyrimidinium-5-olates, which are represented as mesomeric betaines (MBs). The formation of MBs involves not only N-alkylation of heterocyclic framework but also the rearrangement leading to a change in the type of fusion between pyrimidine and 1,2,4-triazole fragments. The structures of the obtained products were confirmed by the X-ray analysis and measurements of ¹³ C-¹³ C (J_CC ) coupling constants in the 1D ¹³ C NMR spectra of selectively ¹³ C-labeled samples. Treatment of the betaines with lithium bis(trimethylsilyl)amide (LiHMDS) gave anionic carbenes, which were detected by ¹³ C NMR spectroscopy and were trapped by reactions with phenyl isothiocyanate and sulfur. Density functional theory (DFT) and the quantum theory of atoms in molecules (QTAIM) analyses allowed for an insight into the electronic structure of the obtained betaines and N-heterocyclic carbene derivatives.

Plant Coumarins with Anti-HIV Activity: Isolation and Mechanisms of Action

This review summarizes and systematizes the literature on the anti-HIV activity of plant coumarins with emphasis on isolation and the mechanism of their antiviral action. This review summarizes the information on the anti-HIV properties of simple coumarins as well as annulated furano- and pyranocoumarins and shows that coumarins of plant origin can act by several mechanisms: inhibition of HIV reverse transcriptase and integrase, inhibition of cellular factors that regulate HIV-1 replication, and transmission of viral particles from infected macrophages to healthy ones. It is important to note that some pyranocoumarins are able to act through several mechanisms or bind to several sites, which ensures the resistance of these compounds to HIV mutations. Here we review the last two decades of research on the anti-HIV activity of naturally occurring coumarins.

Combination of a Chaperone Synthesis Inducer and an Inhibitor of GAPDH Aggregation for Rehabilitation after Traumatic Brain Injury: A Pilot Study

The recovery period after traumatic brain injury (TBI) is often complicated by secondary damage that may last for days or even months after trauma. Two proteins, Hsp70 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), were recently described as modulating post-traumatic processes, and in this study, we test them as targets for combination therapy using an inhibitor of GAPDH aggregation (derivative of hydrocortisone RX624) and an inducer of Hsp70 synthesis (the pyrrolylazine derivative PQ-29). The protective effect of the combination on C6 rat glioblastoma cells treated with the cerebrospinal fluid of traumatized animals resulted in an increase in the cell index and in a reduced level of apoptosis. Using a rat weight drop model of TBI, we found that the combined use of both drugs prevented memory impairment and motor deficits, as well as a reduction of neurons and accumulation of GAPDH aggregates in brain tissue. In conclusion, we developed and tested a new approach to the treatment of TBI based on influencing distinct molecular mechanisms in brain cells.

Fluorescent Pyranoindole Congeners: Synthesis and Photophysical Properties of Pyrano[3,2-f], [2,3-g], [2,3-f], and [2,3-e]Indoles

This paper reports the synthesis of four types of annulated pyranoindole congeners: pyrano[3,2-f]indole, pyrano[2,3-g]indole, pyrano[2,3-f]indole, and pyrano[2,3-e]indole and photophysical studies in this series. The synthesis of pyrano[3,2-f], [2,3-g], and [2,3-e]indoles involve a tandem of Bischler-Möhlau reaction of 3-aminophenol with benzoin to form 6-hydroxy- or 4-hydroxyindole followed by Pechmann condensation of these hydroxyindoles with β-ketoesters. Pyrano[2,3-f]indoles were synthesized through the Nenitzescu reaction of p-benzoquinone and ethyl aminocrotonates and subsequent Pechmann condensation of the obtained 5-hydroxyindole derivatives. Among the pyranoindoles studied, the most promising were pyrano[3,2-f] and [2,3-g]indoles. These compounds were characterized by moderate to high quantum yields (30-89%) and a large (9000-15,000 cm^-1) Stokes shift. More detailed photophysical studies were carried out for a series of the most promising derivatives of pyrano[3,2-f] and [2,3-g]indoles to demonstrate their positive solvatochromism, and the data collected was analyzed using Lippert-Mataga equation. Quantum chemical calculations were performed to deepen the knowledge of the absorption and emission properties of pyrano[3,2-f] and [2,3-g]indoles as well as to explain their unusual geometries and electronic structures.

Triazavirin-A Novel Effective Antiviral Drug

This review outlines the data of numerous studies relating to the broad-spectrum antiviral drug Triazavirin that was launched on the Russian pharmaceutical market in 2014 as an anti-influenza drug (the international non-patented name is Riamilovir). The range of antiviral activity of Triazavirin has been significantly expanded during recent years; in particular, it has been shown that Triazavirin exhibits activity against tick-borne encephalitis, Rift Valley fever, West Nile fever, and other infections of viral etiology. This drug has been approved for treatment of influenza and acute respiratory infections by the Russian Ministry of Health on the basis of comprehensive clinical trials involving over 450 patients. Triazavirin was found to be a highly effective and well-tolerated drug, allowing its over-the-counter sale. The recently published data on the use of Triazavirin in clinical practice for the treatment of patients with COVID-19 are discussed, with special attention paid to potential biological targets for this drug.

Mechanochemical Approach towards Multi-Functionalized 1,2,3-Triazoles and Anti-Seizure Drug Rufinamide Analogs Using Copper Beads

Highly regiospecific, copper-salt-free and neat conditions have been demonstrated for the 1,3-dipolar azide-alkyne cycloaddition (AAC) reactions under mechanochemical conditions. A group of structurally challenging alkynes and heterocyclic derivatives was efficiently implemented to achieve highly functionalized 1,4-disubstituted-1,2,3-triazoles in good to excellent yield by using the Cu beads without generation of unwanted byproducts. Furthermore, the high-speed ball milling (HSBM) strategy has also been extended to the synthesis of the commercially available pharmaceutical agent, Rufinamide, an antiepileptic drug (AED) and its analogues. The same strategy was also applied for the synthesis of the Cl-derivative of Rufinamide. Analysis of the single crystal XRD data of the triazole was also performed for the final structural confirmation. The Cu beads are easily recoverable from the reaction mixture and used for the further reactions without any special treatment.

MnO2-Mediated Oxidative Cyclization of "Formal" Schiff's Bases: Easy Access to Diverse Naphthofuro-Annulated Triazines

A different type of MnO₂-induced oxidative cyclization of dihydrotriazines has been developed. These dihydrotriazines are considered as a "formal" Schiff's base. This method provided easy access to naphthofuro-fused triazine via the C-C/C-O oxidative coupling reaction. The reaction sequence comprised the nucleophilic addition of 2-naphthol or phenol to 1,2,4-triazine, followed by oxidative cyclization. The scope and limitations of this novel coupling reaction have been investigated. Further application of the synthesized compound has been demonstrated by synthesizing carbazole-substituted benzofuro-fused triazines. The scalability of the reaction was demonstrated at a 40 mmol load. The mechanistic study strongly suggests that this reaction proceeds through the formation of an O-coordinated manganese complex.

Assessment on facile Diels-Alder approach of α-pyrone and terpenoquinone for the expedient synthesis of various natural scaffolds

The development of highly facile synthetic procedures for the expedient synthesis of complex natural molecules is always in demand. As this aspect, the Diels-Alder reaction (DAR) has a versatile approach to the synthesis of complex natural compounds and highly regio-/stereoselcetive heterocyclic scaffolds. Additionally, α-pyrone and terpenoquinone are two versatile key intermediates that are prevalent in various bioactive natural compounds for instance, (±)-crinine, (±)-joubertinamine, (±)-pancratistatin, (-)-cyclozonarone, and 8-ephipuupehedione, etc. Hence, the current review summarizes the Diels-Alder reaction application of α-pyrone and terpenoquinone to the constructive synthesis of various natural products over the past two decades (2001-2021). Equally, it serves as a stencil for the invention and development of new synthetic strategies for high-complex molecular structured natural and heterocyclic molecules.

2,7-Diazapyrenes: a brief review on synthetic strategies and application opportunities

2,7-Diazapyrenes are promising azaaromatic scaffolds with a unique structural geometry and supramolecular properties. This core moiety and its derivatives with some N-methyl cations like N-methyl-2,7,-diazapyrenium, and N,N'-dimethyl-2,7-diazapyrenium attract special attention due to their challenging photophysical properties, especially in the context of interactions with DNA and some of its mononucleotides. This review focuses on the analysis of the main synthetic approaches to 2,7-diazapyrene and its functional derivatives employing various strategies under different reaction conditions. The opportunities of applications of 2,7-diazapyrenes, including their remarkable photophysical and supramolecular properties, DNA-bindings, in sensors, molecular electronics, supramolecular systems, and related areas are also highlighted.

Synthesis and Biological Investigation of 1,2,4-Triazolo[4,3-a]azines as Potential HSF1 Inductors

Derivatives of fused 1,2,4-triazines containing heterocyclic and metallocene fragments were obtained by one-pot oxidative cyclization of heterocyclic hydrazones in the presence of hypervalent iodine(III) reagents. For 1,2,4-triazolo[4,3-a]azines, the ability to activate HSF1 was investigated. The obtained compounds were shown to increase the degree of HSF1 activation. It was shown that the 1,2,4-triazines can be used to induce Hsp70 expression and decrease the extent of mutant HTT aggregate formation.

Synthesis of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines and investigation of their fungistatic activity

A series of novel [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines has been synthesized through oxidation reaction of the corresponding 3,6-disubstituted 1,2,4,5-tetrazines bearing amidine fragments. It is shown that the heterocyclic systems obtained can be modified easily at C(3) position in the reactions with aliphatic alcohols and amines. Also, the reactivity of [1,2,4]triazolo[1,5-b][1,2,4,5]tetrazines towards CH-active compounds has been studied. The obtained triazolo[1,5-b]annulated 1,2,4,5-tetrazines proved to be active in micromolar concentrations in vitro against filamentous anthropophilic and zooanthropophilic dermatophyte fungi (Trichophyton, Microsporum and Epidermofiton), which cause skin and its appendages (hair, nails) diseases.

Coumarin-pyridine push-pull fluorophores: Synthesis and photophysical studies

A series of coumarin-pyridine-based push-pull fluorophores were prepared starting from 1,2,4-triazines by using direct C-H functionalization (S_N^H-reaction)-Diels-Alder-retro Diels-Alder domino reaction sequence. This efficient synthetic strategy allowed to obtain a series of 19 coumarin-pyridine fluorophores. Their photophysical properties were studied. While pyridine-substituted derivatives of 4-alkylcoumarins may be considered as alternative to coumarin dyes characterized by emission maxima mainly in a visible region with wavelengths of 402-415 nm, absorption in the UV range at 210-307 nm, and good photoluminescence quantum yields of 6-19%, all the derivatives of 4-phenylcoumarin did not exhibit any noticeable fluorescence. More detailed photophysical studies were carried out for two the most representative derivatives of 4-alkyl-coumarin-pyridines to demonstrate their positive solvatochromism, and the collected data were analyzed by using Lippert-Mataga equation, as well as Kosower and Dimroth/Reichardt scales. The obtained results demonstrate that the combining two chromophore systems, such as 2,5-diarylpyridine and coumarin ones, is promising in terms of improving the photophysical properties of the new coumarin-pyridine hybrid compounds.

A BF3-mediated C–H/C–Li coupling of 1,3,7-triazapyrene with 2-thienyllithium in the design of push–pull fluorophores and chemosensors for nitroaromatics

A BF3-mediated strategy of oxidative nucleophilic substitution of hydrogen affords mono- and bis-substituted thiophene-derived 1,3,7-triazapyrene fluorophores of interest in the design of luminescent materials and chemosensors for nitroaromatics.

Individual iron(iii) glycerolate: synthesis and characterisation

Iron(ii) and iron(iii) salts of strong acids form iron glycerolates on heating at 180 °C with glycerol in the presence of an equivalent amount of alkali. Individual iron(iii) glycerolate was obtained for the first time. When Fe₃O₄ magnetic nanoparticles were heated with glycerol, an iron(iii) glycerolate shell was formed on their surface.

Individual iron(iii) glycerolate was obtained and characterized; a method for the preparation of an iron(iii) glycerolate shell on the surface of Fe₃O₄ MNPs was proposed.

Functionalized 1,3,5-triazine derivatives as components for photo- and electroluminescent materials

Extensive research on the synthesis and application of triazine derivatives for electroluminescent devices, phosphorescent emitters, hole transport materials for perovskite solar cells, and TADF materials has been published recently. This...

New naphtho[1,8-<i>ef</i>]perimidines: synthesis, fluorescence studies and application for detection of nitroanalytes

A rational approach to the synthesis of substituted naphtho[1,8-ef]perimidines based on SNH methodology and cyclization  reaction in the series of condensed azines with naphthalene substituents was presented. Photophysical properties of the obtained fluorophores were studied, in particular, green fluorescence in the 485–536 nm range with quantum yield up to 32.4% was detected. HOMO-LUMO energy values and distributions for the new compounds were calculated by the DFT method in comparison with nitroanalytes and perylene. Based on the data obtained, as well as on the results of fluorescence titration, the possibility of using the new diazaperylenes as potential chemosensors for the visual detection of nitro-containing explosives was shown.

New 2,5-bis(2-ethylhexyl)pyrrolo[3,4-<i>c</i>]pyrrole-1,4(<i>2H,5H</i>)-dione-2,2’-bipyridine-based co-polymer, synthesis, photophysical properties and response to metal cations

A new co-polymer based on fragments of 2-(2-pyridyl)monoazatriphenylene and 2,5-bis (2-ethylhexyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione was prepared by using the Sonogashira reaction. The photophysical properties of the polymer were studied. The presence of a strong bathochromic shift of the absorption and emission maxima in comparison with the previously described monomer units is shown. The polymer exhibits an intense “turn-off” response toward Cu2+ cations.

Benzo[<i>de</i>]naphtho[1,8-<i>gh</i>]quinolines: synthesis, photophysical studies and nitro explosives detection

A rational synthetic approach to substituted naphtho[1,8-gh]quinolines using intramolecular cyclization in the presence of potassium in the series of (naphthalen-1-yl)isoquinolines is described. The photophysical properties of the obtained compounds were studied; in particular, fluorescence emission was detected in the range 454 - 482 nm with a quantum yield of up to 54%. We also calculated the HOMO-LUMO energies and optimized molecular structures for the resulting fluorophores. Based on the results of fluorescence titration, the Stern-Volmer constants (up to 21587 M-1) and the detection limits of nitroanalytes (up to 1.4 ppm) were calculated, confirming the possibility of their use as potential chemosensors for the visual detection of nitro-containing explosives.

15N Chemical Shifts and JNN-Couplings as Diagnostic Tools for Determination of the Azide-Tetrazole Equilibrium in Tetrazoloazines

Selectively ¹⁵N-labeled tetrazolo[1,5-b][1,2,4]triazines and tetrazolo[1,5-a]pyrimidines bearing one, two, or three ¹⁵N labels were synthesized. The synthesized compounds were studied by ¹H, ¹³C, and ¹⁵N NMR spectroscopy in DMSO and TFA solutions, where the azide-tetrazole equilibrium can lead to the formation of two tetrazole (T, T') isomers and one azide (A) isomer for each compound. Incorporation of the ¹⁵N-label(s) leads to the appearance of ¹⁵N-¹⁵N coupling constants (J_NN), which can be easily measured via simple 1D ¹⁵N NMR spectra, even at natural abundance between labeled and unlabeled ¹⁵N atoms. The chemical shifts for the ¹⁵N nuclei in the azole moiety are very sensitive to the ring opening and azide formation, thus providing information about the azido-tetrazole equilibrium. At the same time, the ^1-2J_NN couplings between ¹⁵N-labeled atoms in the azole and azine fragments unambiguously determine the fusion type between tetrazole and azine rings in the cyclic isomers T and T'. Thus, combined analysis of ¹⁵N chemical shifts and J_NN values in selectively isotope-enriched compounds provides an effective diagnostic tool for direct structural determination of tetrazole isomers and azide form in solution. This method was found to be the most simple and efficient way to study the azido-tetrazole equilibrium.

Dataset of NMR-spectra pyrrolyl- and indolylazines and evidence of their ability to induce heat shock genes expression in human neurons

These data are related to our previous paper “Synthesis and approbation of new neuroprotective chemicals of pyrrolyl- and indolylazine classes in a cell model of Alzheimer's disease” (Dutysheva et al., 2021), in which we demonstrate neuroprotective abilities of pyrrolyl- and indolylazines in a cell model of Alzheimer's disease. Using a novel procedure of photocatalysis we have synthesized a group of new compounds. The current article presents nuclear magnetic resonance spectra including heteronuclear single quantum coherence spectra of chemicals synthesized by us. The effect of new compounds have on heat shock proteins genes expression in reprogrammed human neurons are presented. We also presented data that verify neuronal phenotype of reprogrammed cells.

Design and Antioxidant Properties of Bifunctional 2H-Imidazole-Derived Phenolic Compounds-A New Family of Effective Inhibitors for Oxidative Stress-Associated Destructive Processes

The synthesis of inhibitors for oxidative stress-associated destructive processes based on 2H-imidazole-derived phenolic compounds affording the bifunctional 2H-imidazole-derived phenolic compounds in good-to-excellent yields was reported. In particular, a series of bifunctional organic molecules of the 5-aryl-2H-imidazole family of various architectures bearing both electron-donating and electron-withdrawing substituents in the aryl fragment along with the different arrangements of the hydroxy groups in the polyphenol moiety, namely derivatives of phloroglucinol, pyrogallol, hydroxyquinol, including previously unknown water-soluble molecules, were studied. The structural and antioxidant properties of these bifunctional 5-aryl-2H-imidazoles were comprehensively studied. The redox transformations of the synthesized compounds were carried out. The integrated approach based on single and mixed mechanisms of antioxidant action, namely the AOC, ARC, Folin, and DPPH assays, were applied to estimate antioxidant activities. The relationship “structure-antioxidant properties” was established for each of the antioxidant action mechanisms. The conjugation effect was shown to result in a decrease in the mobility of the hydrogen atom, thus complicating the process of electron transfer in nearly all cases. On the contrary, the conjugation in imidazolyl substituted phloroglucinols was found to enhance their activity through the hydrogen transfer mechanism. Imidazole-derived polyphenolic compounds bearing the most electron-withdrawing functionality, namely the nitro group, were established to possess the higher values for both antioxidant and antiradical capacities. It was demonstrated that in the case of phloroglucinol derivatives, the conjugation effect resulted in a significant increase in the antiradical capacity (ARC) for a whole family of the considered 2H-imidazole-derived phenolic compounds in comparison with the corresponding unsubstituted phenols. Particularly, conjugation of the polyphenolic subunit with 2,2-dimethyl-5-(4-nitrophenyl)-2H-imidazol-4-yl fragment was shown to increase ARC from 2.26 to 5.16 (10⁴ mol-eq/L). This means that the considered family of compounds is capable of exhibiting an antioxidant activity via transferring a hydrogen atom, exceeding the activity of known natural polyphenolic compounds.

Metal-Free C-H/C-H Coupling of 2H-Imidazole 1-Oxides with Polyphenols toward Imidazole-Linked Polyphenolic Compounds

The methodology of nucleophilic substitution of hydrogen (S_N^H) was successfully applied as a convenient synthetic tool to afford azaheterocyclic derivatives of phenols of various architectures. A series of 26 novel imidazole-linked polyphenolic compounds were first prepared in 72-95% yields through the direct metal-free C-H/C-H coupling of polyphenols with 2H-imidazole 1-oxides. Comprehensive studies on the reaction condition optimization, scope, and limitations enabled the development of a straightforward method toward novel bifunctional derivatives bearing both phenolic and imidazole scaffolds of particular interest in the design of challenging molecules for versatile applications in medicinal chemistry and materials science.

Novel Pentafluorophenyl- and Alkoxyphenyl-Appended 2,2′-Bipyridine Push–Pull Fluorophores: A Convenient Synthesis and Photophysical Studies

A convenient method for the synthesis of new highly in non-polar solvents soluble photoactive pentafluorophenyl-substituted and extended alkoxyphenyl-substituted 2,2′-bipyridines is reported. The synthetic strategy for the preparation of such ligands involves a sequence of several structural transformations, such as O-alkylation, nucleophilic substitution of hydrogen (SN H) in 1,2,4-triazine precursors via the ‘addition–elimination’ scheme, and the subsequent conversion of the obtained 1,2,4-triazines into 2,2′-bipyridines by means of the aza-Diels–Alder reaction. The photophysical properties of the synthesized novel pentafluoroaryl-substituted 2,2′-bipyridines were comprehensively studied. The obtained photophysical data indicate the competitive advantages of the herein reported pentafluoroarylated push–pull fluorophores, bearing extended aliphatic moieties, over their analogues containing benzoxy or phenolic fragments in terms of improvement in quantum yield and well-pronounced positive solvatochromism confirmed by the mathematical analysis according to the Lippert–Mataga equation.

Electrochemical Aromatization of Dihydroazines: Effect of Chalco­genophosphoryl (CGP) Substituents on Anodic Oxidation of 9-CGP-9,10-dihydroacridine

The effect of chalcogenophosphoryl fragments on the anodic oxidation of 9-chalcogenophosphoryl-9,10-dihydroacridines was studied in detail. The data of X-ray structural analyses, quantum chemical calculations, and cyclic voltammetry measurements obtained for these compounds provide an explanation of the observed features. The direct electrochemical phosphorylation of acridine was first carried out successfully.

Oxidative C-H/C-H Coupling of Dipyrromethanes with Azines by TiO2-Based Photocatalytic System. Synthesis of New BODIPY Dyes and Their Photophysical and Electrochemical Properties

Oxidative C-H/C-H coupling reactions of dipyrromethanes with azines in the presence of a heterophase oxidative photocatalytic system (O₂/TiO₂/visible light irradiation) were carried out. As a result of cyclization of obtained compounds with boron trifluoride etherate, new hetaryl-containing derivatives of 4,4-difluoro-4-boron-3a,4a-diaza-s-indacene were synthesized. For the obtained compounds, absorption and luminescence spectra, quantum yields of luminescence as well as cyclic volt-amperograms were measured.

Oxidative Aromatization of 4,7-Dihydro-6-nitroazolo[1,5-a]pyrimidines: Synthetic Possibilities and Limitations, Mechanism of Destruction, and the Theoretical and Experimental Substantiation

The reaction tolerance of the multicomponent process between 3-aminoazoles, 1-morpholino-2-nitroalkenes, and aldehydes was studied. The main patterns of this reaction have been established. Conditions for the oxidation of 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines were selected. Previous claims that the 4,7-dihydro-6-nitroazolo[1,5-a]pyrimidines could not be aromatised have now been refuted. Compounds with an electron-donor substituent at position seven undergo decomposition during oxidation. The phenomenon was explained based on experimental data, electro-chemical experiment, and quantum-chemical calculation. The mechanism of oxidative degradation has been proposed.

Synthesis and approbation of new neuroprotective chemicals of pyrrolyl- and indolylazine classes in a cell model of Alzheimer's disease

One of the major causes of neurodegeneration in the pathogenesis of Alzheimer's disease is the accumulation of cytotoxic amyloid species within the intercellular compartments of the brain. The efficacy of the anti-proteotoxic mechanism based on the molecular chaperones Hsp70 and Hsp90 in numerous types of neurons is often low, while its pharmacological enhancement has been shown to ameliorate the physiological and cognitive functions of the brain. Suggesting that the chemicals able to induce heat shock protein synthesis and therefore rescue neural cells from cytotoxicity associated with amyloid, we have synthesized a group of pyrrolyl- and indolylazines that cause the accumulation of heat shock proteins, using a novel method of photocatalysis that is employed in green chemistry. The selected compounds were tested in a cell model of Alzheimer's disease and demonstrated a pronounced neuroprotective effect. These substances increased the survival of neurons, blocked the activation of β-galactosidase, and prevented apoptosis in neurons cultured in the presence of β-amyloid.

Antiviral drug Triazavirin, selectively labeled with 2H, 13C, and 15N stable isotopes. Synthesis and properties

Isotope-labeled antiviral drug Triazavirin containing 2H, 13C, and 15N atoms in its structure has been synthesized. 13C2H3I and KS13CN served as donors of 13C isotopes. The use of 13С-MeI containing 2H atoms made it possible to additionally incorporate deuterium labels into the structure of the compound. The 15N atoms were incorporated using 15N-enriched sodium nitrite, aminoguanidine carbonate, and ethyl nitroacetate. The resulting 2H3,13C2,15N3-Triazavirin was characterized by NMR spectroscopy.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10593-021-02927-1.

5-Aryl-6-arylthio-2,2'-bipyridine and 6-Arylthio-2,5-diarylpyridine Fluorophores: Pot, Atom, Step Economic (PASE) Synthesis and Photophysical Studies

A PASE (pot, step, atom, economic) synthetic approach to 5-aryl-6-arylthio-2,2'-bipyridine and 6-arylthio-2,5-diarylpyridine ligands/fluorophores has been reported via S_NH in 6-aryl-5H-1,2,4-triazines/aza-Diels-Alder reaction sequence. In this article, the "1,2,4-triazine" methodology was successfully used for the synthesis of C6-thiophenol-substituted (2,2'-bi)pyridines as it is well known that thio-substituted (bi)pyridines and their aza-analogs are of wide practical interest. The photophysical properties of the obtained compounds are studied and compared with those reported earlier for 6-substituted 2,2'-bipyridines. The influence of the nature of substituents in the 6-arylthio(bi)pyridine core on the photophysical properties is discussed. It was observed that the new compounds exhibited promising photophysical properties and could be considered as potential push-pull fluorophores. In addition, they demonstrated greater Stokes shift values compared to the previously described 6-H, 6-arylamino and 6-pentafluoro-2,2'-bipyridines and higher fluorescence quantum yields values compare to pentafluorophenyl-substituted 2,2'-bipyridines. Depending on a nature of (bi)pyridine fluorophore LE (locally excited) and/or ICT (intramolecular charge transfer) state were prevailing in emission spectra.

Biodegradation of trichlorobiphenyls and their hydroxylated derivatives by Rhodococcus-strains

A possibility of using a complex approach is considered to explain features of biodestruction of polychlorinated biphenyls (PCBs), which are known to be persistent organic pollutants. The approach comprises the following main stages: (i) chemical modification of chloroarenes by hydroxylation and (ii) bacterial degradation of the hydroxylated derivatives. This approach is applicable to individual trichlorobiphenyls (PCB 29, PCB 30) and to a widespread mixture Trikhlorbifenil (analog of Aroclor 1242 and Delor 103). As bacterial strain destructors, the Rhodococcus-strains (КТ112-7, СН628, P25) were used. It was established that the main metabolites of microbial biodegradation of both polychlorobiphenyls and their hydroxy derivatives are polychloro- and hydroxy(polychloro)benzoic acids, which allows an assumption to be made about possible further biodegradation of these compounds down to the products of the base exchange reaction in a cell: water, carbon dioxide and chlorine compounds. The study discusses the effect that the structure of PCBs congeners causes on the conversion by hydroxylation, on the biodegradation rate of both PCBs and their hydroxy derivatives, and on the metabolite formation levels.

Effects of Succinate-Containing Preparation on Characteristics of Rat Erythrocytes in Exhaustive Swimming with a Load

We studied the dynamics of the red blood cell composition of Wistar male rats at rest and when swimming with a load (4% body weight) before and after administration of a succinatecontaining preparation (meso-2,3-dimercaptosuccinic acid). In rats receiving the succinatecontaining preparation, a decrease in the number of red blood cells and an increase in their volume and absolute and relative number of reticulocytes were observed at rest in comparison with vivarium control. In rats exposed to exhaustive swimming after preliminary administration of the test preparation (12 h before the test), we observed a decrease in hematocrit and erythrocyte diameter in comparison with the corresponding parameters in rats not treated with the preparation; the level of hemoglobin did not change. The pattern of changes in the cellular composition of red blood in rats at rest and during swimming against the background of treatment with the succinate-containing preparation in comparison with vivarium control is considered as a result of its effect on physical exercise under conditions of stabilization of hemoglobin and hematocrit levels, activation of proliferative activity of red bone marrow, and an increase in time of swimming to exhaustion by 2.8 times.