The electrophilic halogenation of spirocyclic olefins containing an imidazolone fragment were studied using techniques of dropwise addition of halogen and diffusion mixing with halogen vapor. The bromination reactions providing the formation of trans-1,2-dihalogenation products (when reactions with bridging olefin are carried out in chloroform) or skeletal rearrangements (reactions in acetonitrile or methanol) are most chemo- and stereoselective. Chlorination is nonselective with the formation of mixtures of products, and success of iodination is determined by the choice of the substrate and reaction conditions.

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 convenient one-pot synthesis of α-bromoacrylic acid esters followed by their conversion into α-bromo-substituted β-amino acid esters via Michael addition with secondary cyclic amines is proposed. Among the amines, morpholine turned most suitable.

A method has been developed for the preparation of a new type of dispiro derivative, 5''-bromo-2-[(4-chlorophenyl)sulfanyl]-1'-methyl-1,4'-diphenyldispiro[imidazole-4,3'-pyrrolidine-2',3''-indoline]-2'',5(1H)-dione, starting from 2-thiohydantoin and using a 1,3-dipolar cycloaddition reaction. The configuration of the target dispiro derivative was unambiguously established by physicochemical methods.

New type dispiroindolinones, dispiroimidazolidine-4,3′-pyrrolidine-2′,3″-indolinones unsubstituted at position 4′ of the central pyrrolidine ring, were synthesized by the 1,3-dipolar cycloaddition of azomethine ylides, generated from N -alkyl-substituted amino acids and isatines, to 5-methylidene-substituted 3-phenylhydantoin.