A widely applicable synthesis of medicinal chemistry-relevant 2-aminobenzo[b]thiophenes has been achieved from ortho-halo-substituted thioamides of 2-arylacetic acids through a t-BuOK-promoted intramolecular C-S bond formation under transition-metal-free conditions. The operationally simple, high-yielding protocol is based on readily accessible substrates and tolerates a variety of functional groups. Density functional theory (DFT) studies, along with mechanistic investigations, including EPR spin trapping experiments, were conducted to elucidate a plausible reaction mechanism.

Efficient regioselective one-pot approaches toward 5- and 3-CF3-isoxazoles were elaborated using reaction of hydroxylamine and its hydrochloride in ethanol. The reaction direction is easily switched by the acidity of the reaction media. In acidic conditions 3-CF3-isoxazoles are formed while 5-CF3-isoxazoles can be synthesized in basic media. High (up to 99%) yields, mild conditions, and simplicity of the reaction protocol are the advantages of the proposed methods. The reaction mechanism and regioselectivity were explained by DFT calculations.

The 1,3-dipolar cycloaddition of nitrile imines to thiazolo[3,2-a]pyrimidine imines featuring both endocyclic and exocyclic C═N bonds was first reported. This reaction resulted in the regio- and stereoselective attachment of two dipole moieties, accompanied by peculiar skeletal rearrangements within the thiazolone fragment. Any products of only dipole addition cannot be isolated. The observed reactivity was explained using DFT protocols to investigate the cyclization mechanism of nitrile imines with thiazolo[3,2-a]pyrimidines.

The Suzuki reaction with 4,4-dichoro-1,2-diaza-but-1,3-dienes opened access to doubly arylated diazadienes prepared in up to 95% yield. It was found that treatment of 4,4-diaryl-1,2-diaza-butenes with acid results in 100% selective intramolecular cyclization to form 1-anilino-2,3-diaryliindoles in up to 99% yield. A broad reaction scope was demonstrated. The mechanism of the reaction was studied by using quantum chemical computations. The reactivity of 1-anilino-2,3-diphenyliindole was investigated to reveal the high synthetic utility of these heterocycles.

Nitrile imines are highly reactive 1,3-dipoles that have found extensive application in [3 + 2]-cycloaddition reactions, offering an efficient approach to introducing pyrazoline and pyrazole motifs into biologically active compounds. In this study, we explore the reactivity of nitrile imines using thiohydantoin derivatives as dipolarophiles, which feature both carbon-carbon and carbon-sulfur bonds suitable for cycloaddition. Typically, carbon-sulfur (C=S) bonds are considered "super dipolarophiles" in nitrile imine cycloaddition reactions. However, we observed an unexpected chemoselectivity in the reaction between nitrile imines and 5-methylidene-2-thiohydantoin, where the reaction surprisingly favored the carbon-carbon (C=C) bond over the expected carbon-sulfur (C=S) bond. Our findings demonstrate that the electronic effects of substituents play a crucial role in determining the reactivity and selectivity of nitrile imines. Specifically, electron-withdrawing groups enhance the reactivity and favor cycloaddition at C=S bonds in thiohydantoins, whereas electron-donating groups or halogens facilitate cycloaddition at C=C bonds. To gain a deeper understanding of the reaction mechanisms and chemoselectivity, we performed density functional theory (DFT) calculations. This work provides a detailed understanding of the factors influencing 1,3-dipolar cycloaddition reactions of nitrile imines, highlighting how electronic effects influence their behavior.

An efficient protocol was developed for the synthesis of highly functionalized 2H-pyrroles. This synthetic approach involves the in situ generation of highly reactive 2,5-dichloro-substituted 2H-pyrroles through dearomative chlorination of the corresponding 1H-pyrroles. The resulting reaction mixture is then treated with various amines, leading to the formation of 2,5-diaminated 2H-pyrroles. Subsequent nucleophilic substitution of fluorine with different N-, O-, and S-nucleophiles allows us to introduce additional functionality into a 2H-pyrrole core. The overall outcome of this reaction sequence is the triple nucleophilic modification of pyrroles. All steps of the sequence were found to be highly efficient, regioselective in the preparation of desired di- and trisubstituted derivatives in up to 96% overall yield. In addition, the computational study of this reaction sequence was carried out using density functional theory (DFT). The results of calculations are in perfect agreement with experimental observations.

An umpolung strategy was used for the preparation of highly functionalized 3-pyrrolin-2-ones. This approach involves dearomative double chlorination of 1H-pyrroles to form highly reactive dichloro-substituted 2H-pyrroles. The resulting intermediate reacts selectively with wet alcohols to form the corresponding alkoxy-substituted 3-pyrrolin-2-ones via double nucleophilic substitution in up to 99% yield. The subsequent reaction with different N-, O-, and S-nucleophiles opens access to highly functionalized pyrrolinones bearing additional functionality. The overall outcome of the reported sequence is step-by-step nucleophilic modification of pyrroles with three different nucleophiles. All steps were found to be highly efficient and 100% regioselective. This transformation proceeds under mild conditions and does not require any catalyst to give final products in very high yields. The obtained experimental results are in perfect agreement with the data obtained by theoretical investigation of these reactions.

Rhodium-catalyzed oxidative coupling of acetanilides and alkynes via C-H activation is the most powerful synthetic tool for producing the indole motif from commercially available precursors. However, this reaction usually requires large catalyst loadings (5 mol% of rhodium). In this study, a 1,2-diphenylcyclopentadienyl ligand-based catalyst was developed that works well at 1 mol% loading of rhodium. DFT calculations of the C-H activation step provided insight into its high catalytic activity. The catalyst efficiency was also demonstrated in the synthesis of naturally occurring isocoumarins, such as polygonolide, tubakialactone B and penicimarine F. The developed catalytic protocols tolerate a wide range of functional groups, for example, halide, nitro, hydroxy, and alkoxy. image

The Barton–Zard reaction of β-fluoro-β-nitrostyrenes with ethyl α-isocyanoacetate was studied. The reaction was found to proceed in a highly chemoselective manner to form preferably 4-fluoropyrroles in up to 77% yield. The corresponding 4-nitrosubstituted pyrroles are formed as minor products of the reaction. The broad scope of β-fluoro-β-nitrostyrenes was demonstrated in the preparation of a variety of fluorinated pyrroles. The obtained experimental results are in perfect agreement with the data obtained by theoretical investigation of this reaction. The subsequent study of synthetic utility of monofluorinated pyrroles was performed to open a way for the development of a variety of functionalized pyrrole derivatives.

A comprehensive theoretical analysis of the electronic structure, reactivity, and ligand properties of various types of carbenes derived from pyridine and diazines (pyridazine, pyrimidine, and pyrazine) was performed. These carbenes are divided into three classes: "normal" N-heterocyclic carbenes (NHCs) bearing one nitrogen atom at the ylidene carbon (1N-NHC), mesoionic carbenes (MIC), and remote-NHCs (r-NHC). These species have a singlet ground state. Carbenes under study bear high-lying lone electron pairs localized on the ylidene carbon atoms making them bases 2-18 pKaH units stronger than the reference imidazol-2-ylidenes. However, such carbenes are thermodynamically and kinetically less stable than conventional imidazol-2-ylidenes. Pyridinium and diazinium carbenes have exceptional ligand properties evaluated using a model (NHC)Rh(CO)2Cl complex: high metal-ligand binding energies and significantly higher electron donation and steric stabilization than those provided by its five-membered ring counterparts. Diazinium carbenes can act as ditopic ligands that bind Lewis acids to both ylidene carbon and nitrogen atoms. Protonation of diazinium carbenes transforms them from strong donors into strong pi-acceptors comparable to phosphites. Theoretical calculations have shown that diazinium carbenes are promising ligands for the construction of complexes photoactive in the NIR region. A new type of chiral ligand C-PyBOX has been developed, promising for use in transition-metal-mediated enantioselective catalytic transformations.

New data on the mineral composition of Lower Triassic terrigenous rocks in the northern Pechora oil- and gas-bearing basin are presented. The relevance of the study is due to the fact that the terrigenous natural reservoirs confined to this part of the section have heterogeneous structure. The purpose of the article was to identify the features of the formation and distribution of minerals that fill the void space of the reservoirs. The optical microscopic, X-ray phase, and electron microscopic study revealed diverse postsedimentary transformations of sandy reservoirs. It is shown that the most widespread are quartz regeneration, transformation of mica-group minerals, as well as the formation of calcite of various generations and authigenic clay minerals. Diagenetic changes in terrigenous rocks play a significant role in the formation of reservoir properties and promote the heterogeneity of reservoirs. The large amount of calcite in sandstone cement leads to a significant decrease in filtration and capacity parameters. The pore cement of chlorite‒smectite composition in the fine-grained sandstones also causes a decrease in the reservoir quality. The coarse- and medium-grained sandstones with a low content of cement (predominantly of the kaolinite or chlorite composition) are characterized by the higher reservoir properties. The chloritic crustification and kaolinitic pore-filling cement facilitate the formation of higher quality reservoirs.

A new easily scalable synthesis of the important for materials chemistry indolo[1,2-f]phenanthridine from commercially available 6-chlorophenanthridine was developed. The suggested transition metal catalyst-free and solvent-free procedure is more ecologically friendly and cost efficient then the known methods. The yields of indolo[1,2-f]phenanthridine synthesized from 6-chlorophenanthridine in three steps were 20% and 26% if the cyclization was carried out solvent-free and in THF in the presence of lithium 2,2,6,6-tetramethylpiperidide, respectively.

A detailed study of the reaction of CF3-ynones with NaN3 was performed. It was found that the reaction permits the selective synthesis of either 4-trifluoroacetyltriazoles or 5-CF3-isoxazoles. The chemoselectivity of the reaction was switchable via acid catalysis. The reaction of CF3-ynones with NaN3 in EtOH produced high yields of 4-trifluoroacetyltriazoles. In contrast, the formation of 5-CF3-isoxazoles was observed under catalysis by acids. This acid-switchable procedure can be performed at sub-gram scale. The possible reaction mechanism was supported by DFT calculations. The synthetic utility of the prepared 4-trifluoroacetyltriazoles was demonstrated.

The development of novel methods and strategies for the formation of fused five-, six-, and seven-membered ring structures is of utmost importance in organic syntheses.

Base-free reaction of dichloroglyoxime with copper(i) acetylides gave 3,3′-biisoxazoles via a nucleophilic substitution of the chlorine atom of dichloroglyoxime with the acetylene moiety followed by cyclization of the intermediate formed. The effects of the solvent on the product yields were studied. In the case of substituted copper acetylides, 5,5′-disubstituted 3,3′-biisoxazoles were obtained in the yields from moderate to high and high regioselectivity.

A new efficient solvent-free procedure for the C-O cross-coupling between (hetero)aryl halides with phenols, primary alkanols, or (hetero)arylmethanols using Pd-2(dba)(3)/ButBrettPhos catalytic system is proposed using 23 examples.

The effect of various factors on the activity and selectivity of palladium N-heterocyclic carbene (NHC) complexes in the telomerization of isoprene with alcohols has been studied. The leaving group of the palladium complex does not affect the results of telomerization of isoprene with methanol, which leads to a predominant formation of the head-to-head product. The use of more fatty alcohols as nucleophiles changes the reaction selectivity toward a preferential formation of the head-to-tail isomers.

We have investigated the role of ring sizes and substituents in NHC ligands in some (NHC)Au(i) complexes in the hydration of internal alkynes. Despite the fact that using (NHC)Au(i) complexes in the hydration of diarylacetylenes leads to Markovnikov-type products, the precise tuning of ligands allows changing the regioselectivity in arylalkylacetylene hydration to the anti-Markovnikov-type.

A comprehensive theoretical analysis of the electronic structure, reactivity, and ligand properties for various types of divalent derivatives of group 14 elements, tetrylenes, R2E (E = C, Si, Ge, Sn), was performed at the DFT level. For a deeper understanding of the stability and the origin of chemical properties of tetrylenes, molecules stable in the monomeric form in the solid state with real substituents were considered. Tetrylenes stabilized by various factors were studied: steric shielding, attachment of electron-withdrawing substituents to E atom, electron delocalization, and intramolecular coordination bonding. The effect of various stabilization factors on the chemical and ligand properties of tetrylenes was investigated using theoretical modeling. The obtained data can be used for the rational design of tetrylenes and their complexes with transition metals and can also serve as a comprehensive tutorial on the theoretical aspects of the structure and reactivity of tetrylenes within one approach and at one level of theory.