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.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A new molecular dyad including a spiropyran and a fluorescein fragment linked by the azomethine spacer was prepared. The chromogenic properties of the molecular dyad are due to the presence of spiropyran moiety showing positive photochromism. The azomethine fragment in the side chain is generally stabilized by an intramolecular hydrogen bond. The existence of two photochromic units allows the control of the chromogenic properties of the molecular dyad through intermolecular H-bond with the solvent. The main conclusions were supported by quantum chemical DFT calculations.

Depending on the reaction conditions, the acylation of 2-ethylnaphtho[2,1- b ]furan leads to the formation of a mixture of 1-acetyl-, 5-acetyl-, and 1,5-diacetyl derivatives with a widely varying ratio of components, the structure of which has been characterized by IR and NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis methods. Quantum-chemical simulations using the DFT B3LYP/6-311++G** method have reproduced the experimental geometry of isomeric acetyl[2,1- b ]furans and indicated their close thermodynamic stability. However, the Fukui indices of the reactivity f − have indicated the preference of the primary attack of the electrophile at the C 5 position ( f − = 0.18) as compared to the C 1 position ( f − = 0.06).

In this study, we develop a program that allows us to reveal DNA receptors, i.e. nucleotide sequences that may form more than one non-canonical structure. The data obtained may be analysed either experimentally or using DNA banks, and refers to the coding, non-coding or promotor region of the gene. These results provide a better understanding of the role that non-canonical structures play in pathological modifications of the genetic apparatus, resulting in tumour formation or inherited disease. They also reveal the effect of single nucleotide polymorphisms on gene expression, indicate so-called "risk regions" in which the substitution of a single nucleotide may lead to increased formation of non-canonical structures, and elucidate the epigenetic mechanisms of microorganism adaptation.

This review is devoted to the scientific achievements of the departments of organic chemistry in higher schools of Russia within the past decade.

By the reaction of 2-chloroindole-3-carbaldehyde with acylhydrazones new acylhydrazones of the indole series have been synthesized, and their structure, the possibility of cyclization to pyrazoloindoles, and complexing properties have been studied. By means of quantum chemical DFT calculations taking into account the solvent effect it was shown that the reaction of 2-chloroindole-3-carbaldehyde and the corresponding acylhydrazine is an exothermic process, irrespective of which final product is formed, indolemethylenehydrazide or pyrazoloindole. Therefore, both possible transformations in the studied reacting system are controlled kinetically and not thermodynamically.

Copper(II) complexes with synthetic oligonucleotides consisting of repeating adenine–thymine and guanine–cytosine complementary base pairs have been studied by UV spectroscopy and simulated by DFT quantum chemical calculations at the B3LYP/6-311G++(d,p) level of theory with inclusion of solvation (hydration) effects. The obtained data suggest selective interaction of copper(II) ions with guanine–cytosine complementary pairs, followed by DNA cross-linking at those sites.

The reactions of 4-chloro-5,7-dinitro-4-benzofurazan with indole and pyrrole derivatives, occurring by SNAr–SEAr mechanism, led to the formation of dihetaryls with intramolecular charge transfer. A method was developed for the annelation of pyrrole and dihydropyrrole ring to nitrobenzofurazan fragment by adding unstabilized azomethine ylide to the С=С bond of dinitrobenzofurazan. The structure of nitrobenzofurazan derivatives was studied by X-ray structural analysis, NMR spectroscopy, and quantum-chemical calculations using ab initio and DFT methods.

Dihetaryls containing superelectrophilic and π-excessive heterocycles were synthesized by the nucleophilic aromatic substitution and cycloaddition. The structures of the compounds and the mechanism of 1,3- N -oxide tautomerism were studied by NMR spectroscopy, X-ray diffraction, and quantum chemical methods. The ability of these compounds to initiate SOX induction, which is probably due to the in vivo generation of nitrogen( ii ) oxide, was quantified using genetically engineered E. coli -based lux biosensors. 7-(1-Methylpyrrol-3-yl)-4,6-dinitrobenzofuroxan is the most active inducer, which is an order of magnitude more effective than nitroglycerin used as the reference compound. The absence of toxicity was established using the E. coli MG 1655 biosensor (pXen7-lux). The DNA protective effect of this leading compound was confirmed using the E. coli MG 1655 biosensor (pRecA-lux).

2-Methyl-3-{[(Z)-3-methyl-5-oxo-1-phenylpyrazol-4-ylidene)methyl]amino}quinazolin-4-one was synthesized by condensation of 5-hydroxy-4-formyl-3-methyl-1-phenylpyrazole with N-amino-2-methylquinazolin-4-one and its structure and properties were studied by IR, 1H, 13C NMR, 2D 1H NMR (COSY) and electronic spectroscopy and mass-spectrometry. By the reaction of compound (III) with Cd(II), Zn(II), and Pb(II) acetates the intracomplex compounds of 1: 2 composition (metal: ligand) were obtained.

Interaction of ortho-diphenylphosphinobenzaldehyde with N-tosyl-1,2-phenylenediamine afforded the product of intramolecular Wittig reaction, N-{2-[2-(Diphenylphosphoryl)benzylamino]phenyl}-4-methylbenzenesulfonamide. Its structure was established on the basis of IR, 1H NMR, 13C NMR, and 2D 1H NMR (COSY) spectroscopy. Reaction mechanism was studied by means of quantum chemistry DFT method. Complexforming property of the obtained diphenylphosphine oxide was investigated.

The 1,3-dipolar cycloaddition of the unstabilized azomethine ylides generated in situ from isatin and proline to the endocyclic C = C bond of the tropylidene ring is absolutely regio- and diastereoselective. The local electrophilicity of the dipolarophile and the local nucleophilicity of the azomethine ylide calculated by the B3LYP/6-31G** method are useful tools for predicting the regioselectivity of cycloaddition. The structure and the three-dimensional structure of the synthesized spiropyrrolizidineoxyindoles were established by correlation NMR spectroscopy and X-ray structural analysis.

The B3LYP/6-31G** quantum chemical method was used to study the mechanism of the oxidative alkylamination of diazinones taking 1,3,6-trimethylpyrimido[4,5-d]pyrimidine-2,4,7(1H,3H,6H)-trione (lumazinone) as an example. The first limiting step of this reaction included a nucleophilic addition of alkylamine with the formation of the σH-adduct, which was oxidized by potassium permanganate in the second step. The alkylamination step proceeded in the associates formed by the lumazinone dimer and several alkylamine molecules involved in both the nucleophilic attack and the bifunctional catalysis of the process. The correlation of the Parr indices with the experimental data was studied for a number of diazinones.

Zwitterionic spirocyclic σ-complexes were synthesized by reaction of 7-chloro-4,6-dinitrobenzofurazan with 2-(benzylamino)cyclohepta-2,4,6-trien-1-one, 2-(benzylamino)cyclohepta-2,4,6-triene-1-thione, and N-benzyl-7-(benzylimino)cyclohepta-1,3,5-trien-1-amine. The structure, stereodynamics, and stability of the spirocycles were studied by NMR spectroscopy, X-ray analysis, and DFT quantum chemical calculations at the B3LYP/6-31G** level of theory. The contribution of heteroatoms to positive charge delocalization and the thermodynamic and kinetic stabilities of the spirocycles increase in the series aminotropone < aminothiotropone < aminotropone imine.