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Diaryliodonium salts are established electrophilic arylation reagents both in transition metal-catalyzed and transition metal-free reaction methods. Herein we present the application of azole-stabilized diaryliodonium salts with additional thiophen-2-yl-ligands as substrates for metal-free nucleophilic arylations. Besides their synthesis, we demonstrate their application in chemoselective nitrations, oxygenations, aminations as well as thiolations under umpolung conditions. Convenient one-pot procedures that are based on their in situ formation are also discussed

The review is devoted to one of the most substantial trends in the chemistry of hypervalent iodine – synthesis, structure, and properties of heterocyclic and pseudoheterocyclic systems based on λ3- and λ5-iodanes. Among the variety of cyclic reagents based on hypervalent iodine, special attention has recently been paid to iodanes having close contact between I and N atoms. The review is addressing the synthetic approaches, structural features, and application of these reagents. The review includes more than 100 literature sources, mainly covering publications from 1990 to 2020 and key research from earlier years.

A novel approach to the preparation of imidazole-substituted cyclic iodonium salts has been developed via the oxidative cyclization of 1-phenyl-5-iodoimidazole using a cheap and available Oxone/H2SO4 oxidative system. The structure of the new polycyclic heteroarenes has been confirmed by single-crystal X-ray diffractometry, revealing the characteristic structure features for cyclic iodonium salts. The newly produced imidazole-flanked cyclic iodonium compounds were found to readily engage in a heterocyclization reaction with elemental sulfur, affording benzo[5,1-b]imidazothiazoles in good yields., The heterocyclization study was supported by the Russian Science Foundation (project No. 17-73-20066). Y.A.V. kindly acknowledges the financial support from the Russian Foundation of Basic Research for the development of oxidative cyclization process (project No. 20-33-90007). This work was funded by Spain’s MINECO (CTQ2017-86936-P), AGAUR (2017 SGR 01051), and additional support from CSIC. The authors would like to acknowledge the Multi-Access Chemical Research Center SB RAS (N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry) and the Center for Chemical Analysis and Materials Research of Saint Petersburg State University for analytical measurements. X-ray structural results were obtained using the material and technical base of the Baikal Analytical Center for Collective Use of the SB RAS.

Pseudocyclic 2-benzimidazolyl-substituted diaryliodonium salts were obtained by the reaction of the corresponding [hydroxy(tosyloxy)iodo]arenes with arenes in the presence of trifluoromethanesulfonic acid. X-ray structural analysis of these iodonium salts confirmed their pseudocyclic structure with a short (2.57–2.58 A) noncovalent I···N interaction. Treatment of 2-benzimidazolyl-substituted diaryliodonium triflates with a base afforded novel five-membered iodine–nitrogen heterocycles.

New nitronyl nitroxides, namely, 2-(4,5-dimethylimidazol-2-yl)- and 2-(4,5-dichloroimidazol-2-yl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyl, were prepared in crystalline form. According to single-crystal X-ray data, intra- and intermolecular hydrogen bonds are formed between NH groups of the imidazole cycles and O atoms of the nitroxide moieties. The intermolecular H-bonds contribute to the alignment of molecules into chains along the a-axis, this alignment causes short intrachain contacts between O and C atoms carrying spin density of opposite signs. Such an arrangement of nitroxides induces ferromagnetic intrachain interactions (J &asymp, 10 cm&minus, 1) between neighboring radicals.