A series of adamantyl-containing alkenes were synthesized by the alkenylation of adamantan-1-ol with secondary alcohols in the presence of sulfuric acid. The scope of application of this reaction was explored to show that the alkenylation reaction with symmetrical dialkylcarbinols occurs in a selective fashion. The alkenylation of adamantan-1-ol with sec-pentanol and its higher homologs gives a mixture of isomeric alkenes. The reactions of substituted adamantanols with isopropanol, butan-2-ol, and cyclohexanol in the presence of sulfuric acid were studied, and a series of new unsaturated derivatives of the adamantane series were obtained.

The aim of the work was to determine the cytotoxicity and the influence of polycyclic derivatives of the framework series on the replicative properties of the SARS-CoV-2 virus in Vero-E6 cell culture in vitro. Materials and methods. The virus inhibiting effect of 50 adamantane and bicyclo[3.3.1]nonane derivatives with carbocyclic and heterocyclic substituents was investigated. The studies were carried out on Vero-E6 cell culture by assessing the cytopathic effect of the virus. The impact of the compounds on the replicative properties of the SARS-CoV-2 virus was estimated by the decrease in virus titer in the presence of the compounds compared to the control. Based on the virus titer values in the presence of a series of successively decreasing concentrations of the compound, the 50 % effective concentration was calculated.Results and discussion. A study of polycyclic derivatives of the framework series has identified two compounds with antiviral properties against the SARS-CoV-2 virus. Among bicyclo[3.3.1]nonane derivatives containing heterocyclic fragments, compound No. 15144 has showed an inhibitory effect against the SARS-CoV-2 virus. The protective effect of the compound was manifested in maximum tolerable concentration (MTC) (70.0 μg/ml) and ½ MTC (35.0 µg/ml). A decrease in virus titers under the influence of MTC by 0.95 lg TCD50/ml, in ½ MTC (35.0 μg/ml) – by 0.35 lg TCID50/ml has been detected. The effective concentration (EC50) value of the compound No. 15144 was 64.0 μg/ml, the MTC/EC50 ratio was 1.09. Compound No. 14838 (adamantane derivative containing carbocyclic fragments) had less pronounced antiviral activity. As a result of research, it has been established that sample No. 14838 at a dose of MTC (45.0 μg/ml) reduces the infectious titer by 0.78 lg TCD50/ml, in ½ MTC (22.5 μg/ml) by 0.15 lg TCD50/ml compared to the control. The EC50 value of compound No. 14838 was 37.0 μg/ml, the MTC/EC50 ratio was 1.22.

A convenient approach for the synthesis of hydrocarbons by transformations of cage alcohols in the presence of 2-propanol and sulfuric acid has been proposed. Scalability, good yields and usage of readily available reagents along with synthetic convenience showed usefulness of proposed approach. This approach made it possible to obtain high preparative yields of difficult-to-reach cage hydrocarbons such as 2-methyladamantane, 2-phenyladamantane and homoadamantane. For some substrates, the potential to obtain corresponding saturated hydrocarbons or alkenylation products by varying the concentration of sulfuric acid under reaction conditions has been demonstrated

The chemistry of heterocyclic compounds has traditionally been and remains a bright area of chemical science in Russia. This is due to the fact that many heterocycles find the widest application. These compounds are the key structural fragments of most drugs, plant protection agents. Many natural compounds are also derivatives of heterocycles. At present, more than half of the hundreds of millions of known chemical compounds are heterocycles. This collective review is devoted to the achievements of Russian chemists in this field over the last 15–20 years. The review presents the achievements of leading heterocyclists representing both RAS institutes and university science. It is worth noting the wide scope of the review, both in terms of the geography of author teams, covering the whole of our large country, and in terms of the diversity of research areas. Practically all major types of heterocycles are represented in the review. The special attention is focused on the practical applications of heterocycles in the design of new drugs and biologically active compounds, high-energy molecules, materials for organic electronics and photovoltaics, new ligands for coordination chemistry, and many other rapidly developing areas. These practical advances would not be possible without the development of new fundamental transformations in heterocyclic chemistry. Bibliography — 2237 references.

A mixture of a nucleophilic substitution product and its isomeric azide resulting from [3,3]-sigmatropic rearrangement was obtained as a result of the reaction of hindered bromides of the adamantane series with sodium azide. Epoxidation reactions of allylic azides of the adamantane series were investigated. The reduction of the syntesized trans -2-(adamantan-1-yl)-3-(azidomethyl)oxirane with lithium alumohydride gave ( S *)-(adamantan-1-yl)[( S *)-aziridin-2-yl]methanol. Under heating with HCl, the latter underwent aziridine ring opening to form (1 S *,2 R *)-1-(adamantan-1-yl)-3-chloro-1-hydroxypropan-2-aminium chloride.

The possibility of constructing various N-, S-, O-containing heterocyclic systems based on the transformations of 1-((Z)-1,4-dibromobut-2-en-2-yl)adamantane was shown. Adamantyl-containing pyrrolines, pyrroles, pyridazinium salt, furan, thiophene, (dihydro)-1,6-benzodioxocine, diazocine, oxazocine, thiazocine were synthesized. It was found that the dihydro derivatives formed as a result of the reactions are unstable and can be easily oxidized by atmospheric oxygen to the corresponding heteroaromatic compounds.

Currently, smallpox, caused by the variola virus belonging to the poxvirus family, has been completely eradicated according to the WHO. However, other representatives of poxviruses, such as vaccinia virus, cowpox virus, ectromelia virus, monkeypox virus, mousepox virus and others, remain in the natural environment and can infect both animals and humans. The pathogens of animal diseases, belonging to the category with a high epidemic risk, have already caused several outbreaks among humans, and can, in an unfavorable combination of circumstances, cause not only an epidemic, but also a pandemic. Despite the fact that there are protocols for the treatment of poxvirus infections, the targeted design of new drugs will increase their availability and expand the arsenal of antiviral chemotherapeutic agents. One of the potential targets of poxviruses is the p37 protein, which is a tecovirimat target. This protein is relatively small, has no homologs among proteins of humans and other mammals and is necessary for the replication of viral particles, which makes it attractive target for virtual screening. Using the I-TASSER modelling and molecular dynamics refinement the p37 orthopox virus protein model was obtained and its was confirmed by ramachandran plot analysis and superimposition of the model with the template protein with similar function. A virtual library of adamantane containing compounds was generated and a number of potential inhibitors were chosen from virtual library using molecular docking. Several compounds bearing adamantane moiety were synthesized and their biological activity was tested in vitro on vaccinia, cowpox and mousepox viruses. The new compounds inhibiting vaccinia virus replication with IC50 concentrations between 0.133 and 0.515 μM were found as a result of the research. The applied approach can be useful in the search of new inhibitors of orthopox reproduction. The proposed approach may be suitable for the design of new poxvirus inhibitors containing cage structural moiety.

An efficient procedure has been developed for the synthesis of secondary amides by the Ritter reaction of cage substrates with a wide series of nitriles in fuming nitric acid and its mixtures.

This article presents the results of a study of electrochemical transformations in aqueous and aprotic media of 5-methyl-6-nitro-7-oxo-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidinide l-arginine monohydrate (1a, Triazid) obtained by electrochemical methods and ESR spectroscopy. The effect of pH on the current and the reduction potential of 1a in an aqueous Britton–Robinson buffer solution was studied. It was found that 1a is irreversibly reduced in aqueous acidic media on a glassy carbon electrode in one stage with the participation of six electrons and the formation of 5-methyl-6-amino-7-oxo-1,2,4-triazolo[1,5-a]pyrimidin. The electroreduction of 1a in DMF on a background of tetrabutylammonium salts proceeds in two stages, controlled by the kinetics of second-order reactions. In the first stage, the reduction of 1a is accompanied by protonation by the initial compound of the basic intermediate products formed in the electrode reaction (self-protonation mechanism). The second quasi-reversible stage of the electroreduction 1a corresponds to the formation of a dianion radical upon the reduction of the heterocyclic anion 5-methyl-6-nitro-7-oxo-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidin, which is formed upon the potentials of the first peak. The ESR spectrum of the radical dianion was recorded upon electroreduction of Triazid in the presence of Bu4NOH. The effect of the formation of ion pairs on the reversibility of the second peak of the 1a transformation is shown. A change in the rate and regioselectivity of the protonation of the dianion radical in the presence of Na+ and Li+ ions is assumed. The results of studying the electroreduction of 1a by ESR spectroscopy with a TEMPO trap make it possible to assume the simultaneous formation of both a nitroxyl radical and a radical with the spin density localized on the nitrogen at the 4 position of the six-membered ring.

Functionally substituted oxiranes were synthesized by epoxidation ofunsaturated compounds of the adamantane series with m-chloroperoxybenzoic acid. Adamantyl-substitutedepibromohydrins reacted with nitrogen, oxygen, and sulfur nucleophiles to giveonly halogen substitution products. 2-(Adamantan-1-yl)-3-hydroxypropanoic acidwas obtained by the reaction of 2-(adamantan-1-yl)-2-(bromomethyl)oxirane with98% nitric acid. Acid-catalyzed ring opening of aminomethyloxiranes affordedtrifunctional derivatives, adamantane-containing aminohalohydrins. Treatment oftrans-2-(adamantan-1-yl)-2-(phenylsulfanylmethyl)oxirane withn-butyllithium gave rise to a mixture ofZ and E isomers of1-(adamantan-1-yl)-3-(phenylsulfanyl)prop-2-en-1-ol, whereas trans-2-(adamantan-1-yl)-3-(phenoxylmethyl)oxiraneunder similar conditions was converted to (E)-3-(adamantan-1-yl)prop-2-enal.

The specifics of transformations of sterically hindered 2-(adamantan-1-yl)aziridine derivatives in the presence of trifluoroacetic anhydride are considered. In a reaction with trifluoroacetic anhydride, trans-2-(adamantan-1-yl)-3-methylaziridine forms the rearrangement product dihydro-1,3-oxazine condensed with homoadamantane, whereas 2-(adamantan-1-yl)aziridine forms a mixture of a derivative of oxazine and N-[1-(adamantan-1-yl)-2-hydroxyethyl]-2,2,2-trifluoroacetamide in equal proportions.

The composition of reaction mixtures obtained by nitroxylation of 13 cage hydrocarbons with 100% nitric acid and its mixtures with acetic acid, acetic anhydride, and methylene chloride has been studied. More reactive substrates react with lowest selectivity regardless of the reaction medium. The primary nitroxylation products of cage hydrocarbons are nitrooxy derivatives. The compositions of reaction mixtures obtained in the reactions of some cage hydrocarbons with nitric anhydride in carbon tetrachloride have been determined.

По реакции Виттига получены арилзамещенные алкены адамантанового ряда. В условиях аллильного бромирования алкенов протекают две конкурирующих реакции - радикальное замещение и радикальное присоединение. Различия в химическом поведении арилзамещенных алкенов продемонстрированы на примере реакции Риттера. В зависимости от строения алкенов и природы кислотного катализатора продуктами реакции могут быть вторичные амиды, производные сульфокислот и -сультон гомоадамантановой структуры.

Mono- and disubstituted aziridines derived from sterically hindered olefins of the adamantane series are synthesized. The opening of the aziridine ring under the action of acids is quite a regio- and stereoselective process. Depending on the nature of the nucleophilic agent, the opening of the 2,2-disubstituted aziridine ring can occur by the S(N)1 or S(N)2 mechanism.

Aryl-substituted alkenes of the adamantane series, 1-[( Z , E )-3-phenylprop-2-en-1-yl]adamantane and 1-[( Z )-3-phenylprop-1-en-1-yl]adamantane, have been synthesized by the Wittig reaction. Their allylic bromination involves two concurrent reactions, radical substitution and raical addition. The different chemical behaviors of the aryl-substituted alkenes have been demonstrated in the Ritter reaction. Depending on the alkene structure and acid catalyst nature, the products are secondary amides, sulfonic acid derivatives, and homoadamantane γ-sultone.

The hepatitis C caused by the hepatitis C virus (HCV) is an acute and/or chronic liver disease ranging in severity from a mild brief ailment to a serious lifelong illness that affects up to 3% of the world population and imposes significant and increasing social, economic, and humanistic burden. Over the past decade, its treatment was revolutionized by the development and introduction into clinical practice of the direct acting antiviral (DAA) agents targeting the non-structural viral proteins NS3/4A, NS5A, and NS5B. However, the current treatment options still have important limitations, thus, the development of new classes of DAAs acting on different viral targets and having better pharmacological profile is highly desirable. The hepatitis C virus p7 viroporin is a relatively small hydrophobic oligomeric viral ion channel that plays a critical role during virus assembly and maturation, making it an attractive and validated target for the development of the cage compound-based inhibitors. Using the homology modeling, molecular dynamics, and molecular docking techniques, we have built a representative set of models of the hepatitis C virus p7 ion channels (Gt1a, Gt1b, Gt1b_L20F, Gt2a, and Gt2b), analyzed the inhibitor binding sites, and identified a number of potential broad-spectrum inhibitor structures targeting them. For one promising compound, the binding to these targets was additionally confirmed and the binding modes and probable mechanisms of action were clarified by the molecular dynamics simulations. A number of compounds were synthesized, and the tests of their antiviral activity (using the BVDV model) and cytotoxicity demonstrate their potential therapeutic usefulness and encourage further more detailed studies. The proposed approach is also suitable for the design of broad-spectrum ligands interacting with other multiple labile targets including various viroporins.

Fifteen adamantane derivatives were synthesized. Preliminary evaluation of their potential as dipeptidyl peptidase 4 (DPP-4) inhibitors was performed in silico by the Microcosm informational technology, PASS system, and docking in AutoDock Vina. The DPP-4 inhibition was studied in vitro. The selectivity of action of the most active compounds was studied by the direct inhibition of human plasma DPP-4 and recombinant human DPP-8. The highest activity was found for the compounds containing a nitrogen atom in the β-position of the side chain, namely, derivatives of adamantane carboxylic acid and N-(3-adamantyl-allyl) thiourea. We demonstrated that the most active compound of the series, 3,5-dimethyladamantane 1-carboxamide, was a selective DPP-4 inhibitor with IC50 53.94 μM.