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.

After the appearance of the green chemistry concept, which was introduced in the chemistry vocabulary in the early 1990s, its main statements have been continuously developed and modified. Currently, there are 10–12 cornerstones that should form the basis for an ideal chemical process. This review analyzes the accumulated experience and achievements towards the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. The review presents the views of leading Russian scientists specializing in various fields of this subject, including homogeneous and heterogeneous catalysis, fine and basic organic synthesis, electrochemistry, polymer chemistry, chemistry based on bio-renewable feedstocks and chemistry of energetic compounds and materials. A new approach to the quantitative evaluation of the environmental friendliness of processes developed by Russian authors is described. The bibliography includes 1761.

In the search for fundamentally new, active, stable, and readily synthetically accessible cycloalkynes as strain-promoted azide–alkyne cycloaddition (SPAAC) reagents for bioorthogonal bioconjugation, we integrated two common approaches: the reagent destabilization by the increase of a ring strain and the transition state stabilization through electronic effects. As a result new SPAAC reagents, heterocyclononynes fused to a heterocyclic core, were created. These compounds can be obtained through a general synthetic route based on four crucial steps: the electrophile-promoted cyclization, Sonogashira coupling, Nicholas reaction, and final deprotection of Co-complexes of cycloalkynes from cobalt. Varying the natures of the heterocycle and heteroatom allows for reaching the optimal stability-reactivity balance for new strained systems. Computational and experimental studies revealed similar SPAAC reactivities for stable 9-membered isocoumarin- and benzothiophene-fused heterocycloalkynes and their unstable 8-membered homologues. We discovered that close reactivity is a result of the interplay of two electronic effects, which stabilize SPAAC transition states (π_in* → σ* and π* → π_in*) with structural effects such as conformational changes from eclipsed to staggered conformations in the cycloalkyne scaffold, that noticeably impact alkyne bending and reactivity. The concerted influence of a heterocycle and a heteroatom on the polarization of a triple bond in highly strained cycles along with a low HOMO–LUMO gap was assumed to be the reason for the unpredictable kinetic instability of all the cyclooctynes and the benzothiophene-fused oxacyclononyne. The applicability of stable isocoumarin-fused azacyclononyne IC9N-BDP-FL for in vitro bioconjugation was exemplified by labeling and visualization of HEK293 cells carrying azido-DNA and azido-glycans.

Two types of immobilized on the amino-functionalized polystyrene-supported acyclic diaminocarbene palladium complexes (ADC-Pd^II) are investigated under Sonogashira cross-coupling conditions. Depending on substituents in the diaminocarbene fragment immobilized ADC-Pd^II, systems are found to have different catalytic activity and stability regarding Pd-leaching. Pd^II-diaminocarbenes possessing protons at both nitrogen atoms smoothly decompose into Pd⁰-containing species providing a catalytic “cocktail system” with high activity and ability to reuse within nine runs. Polymer-supported palladium (II) complex bearing NBn–C_carbene–NH-moiety exhibits greater stability while noticeably lower activity under Sonogashira cross-coupling. Four molecular ADC-Pd^II complexes are also synthesized and investigated with the aim of confirming proposed base-promoted pathway of ADC-Pd^II conversion through carbodiimide into an active Pd⁰ forms.