Kristine V. Balyan

This mini‐review presents recent advances in the transformation of acetylenic compounds mediated by mercury(II) salts. Hg(II) salts serve as both catalysts and stoichiometric reagents in these transformations. Despite their toxicity, Hg(II) salts are inexpensive, stable, and demonstrate high reactivity toward alkynes. Their versatile reactivity enables the synthesis of organomercury compounds (OMCs), heterocyclic compounds containing various heteroatoms, and selected analogues of natural products. OMCs represent an important class of organometallic compounds. They have been used as intermediates or model compounds for studying the fundamental mechanisms of various reactions, particularly mercuration of alkynes and heterocyclic compounds, as well as mercuric intermediate transmetallation and iododemercuration. Recent studies have reported the synthesis of mono‐ and bi‐nuclear OMCs with novel structures containing bithiazole, triazole, benzimidazole, coumarin, and piperidine moieties. Among the Hg(II) salts investigated for the cyclization and hydration of substituted alkynes, mercury(II) triflate has demonstrated high catalytic efficiency and broad applicability. Its effectiveness has been reported in several types of alkyne transformations. This review also summarizes the reactions of various nucleophiles with acetylenic compounds under Hg(II)‐mediated electrophilic activation. Particular attention is given to the regioselectivity of these reactions and the factors that control the formation of the corresponding products.

Two synthon C10 + C3 strategy syntheses of tomato pinworm sex pheromone‐ (E)‐, (Z)‐tridec‐4‐en‐1‐yl acetates‐ were illustrated. The iodinated dec‐1‐yn was successfully applied as a substrate in the synthesis of sex pheromone. The C10‐component‐1‐iododec‐1‐yne was first obtained by the electrophilic iodination of dec‐1‐yne in the presence of cadmium (II) acetate. Additionally, the C3 component was produced from 2‐(3‐bromopropoxy) tetrahydro‐2H‐pyran by the Grignard reaction. The most important stage was the coupling of C10 and C3 components, and condensation in tetrahydrofuran in the presence of dilithium tetrachlorocuprate was carried out due to the great reactivity of the 1‐iododec‐1‐yne. The dispensers were made based on the target sex pheromone and located in the traps. The active preparative forms were tested in field conditions in some regions of Armenia in 2024. Based on the field studies Keiferia lycopersicella belonging to the family Gelechiidae was recorded in Armenia (Armavir, Ararat, Tavush, and Kotayk regions) for the first time.

The present study focuses on the iodination of pyrazoles mediated by cadmium (II) acetate. The objects of research were compounds with pyrazole rings substituted by N‐propargyl, C, N‐alkyl groups. Depending on the molar ratios of the reagents effective ways of obtaining mono‐ and triiodo‐substituted products with the participation of the propargylic fragment in DMSO were elucidated. Induced by the cadmium (II) acetate principles of electrophilic iodination of the C‐4 position of the pyrazole ring containing electron‐donating groups were revealed. The iodination of the pyrazole derivative with only propargylic substituent was found to target the CH‐acidic center of the triple bond and to lead to the corresponding iodoalkyne. An iodo‐substituted product with triple bond is more reactive and prone to further electrophilic iodination forming a triiodo‐substituted derivative. The introduction of methyl groups in the pyrazole ring of derivatives with propargylic substituent contributed to the promotion of competitive iodination reactions due to the increase in nucleophilicity of the pyrazole ring. Dimerized pyrazole rings with carbon atoms in the 4‐th position did not succeed in being iodinated by the mentioned way. Possible pathways for both triple bond and pyrazole ring iodination involving acetyl hypoiodite were proposed.

An efficient procedure has been proposed for the reaction of molecular iodine with phenylacetylene in the presence of cadmium(II) acetate in DMSO at room temperature, and the reactant ratio has been optimized for the iodination process. Mercuration–demercuration of iodoethynylbenzene with molecular iodine and oxidative homocoupling in the presence of dilithium tetrachlorocuprate have been performed.

Several dipropargylic quaternary ammonium salts were synthesized by the reaction of methyldipropargylamine with alkyl esters (C₈-C₁₂) of chloroacetic acid or haloalkanes with the number of carbon atoms C₈–C₁₀. The synthesized N-methyl-N,N-di(prop-2-yn-1-yl)alkan-1-ammonium halides (bromide and iodides), and N-(2-(alkoxy)-2-oxoethyl)-N-methyl-N-(prop-2-yn-1-yl)prop-2-yn-1-ammonium chlorides exhibit high antibacterial activity against gram-positive (Stаphylococcus aureus 209p and Bacillus subtilis 6633), gram-negative (Shigella Flexneri 6858 and Escherichia coli 0-55) microorganisms and antifungal activity against (Candida Albicans, Saccharomyces cerevisiae, and Saccharomyces boulardii).

The exploration of heterocyclic compounds and their fused analogs, featuring key pharmacophore fragments like pyridine, thiophene, pyrimidine, and triazine rings, is pivotal in medicinal chemistry. These compounds possess a wide array of biological activities, making them an intriguing area of study. The quest for new neurotropic drugs among derivatives of these heterocycles with pharmacophore groups remains a significant research challenge. The aim of this research work was to develop a synthesis method for new heterocyclic compounds, evaluate their neurotropic and neuroprotective activities, study histological changes, and perform docking analysis. Classical organic synthesis methods were used in the creation of novel heterocyclic systems containing pharmacophore rings. To evaluate the neurotropic activity of these synthesized compounds, a range of biological assays were employed. Docking analysis was conducted using various software packages and methodologies. The neuroprotective activity of compound 13 was tested in seizures with and without pentylenetetrazole (PTZ) administration. Histopathological examinations were performed in different experimental groups in the hippocampus and the entorhinal cortex. As a result of chemical reactions, 16 new, tetra- and pentacyclic heterocyclic compounds were obtained. The biologically studied compounds exhibited protection against PTZ seizures as well as some psychotropic effects. The biological assays evidenced that 13 of the 16 studied compounds showed a high anticonvulsant activity by antagonism with PTZ. The toxicity of the compounds was low. According to the results of the study of psychotropic activity, it was found that the selected compounds have a sedative effect, except compound 13, which exhibited activating behavior and antianxiety effects (especially compound 13). The studied compounds exhibited antidepressant effects, especially compound 13, which is similar to diazepam. Histopathological examination showed that compound 13 produced moderate changes in the brain and exhibited neuroprotective effects in the entorhinal cortex against PTZ-induced damage, reducing gliosis and neuronal loss. Docking studies revealed that out of 16 compounds, 3 compounds bound to the γ-aminobutyric acid type A (GABA_A) receptor. Thus, the selected compounds demonstrated anticonvulsant, sedative, and activating behavior, and at the same time exhibited antianxiety and antidepressant effects. Compound 13 bound to the GABA_A receptor and exhibited antianxiety, antidepressant, and neuroprotective effects in the entorhinal cortex against PTZ-induced changes.

A convenient and selective method for the preparation of substituted iodoalkynes, iodoalkenes based on the interaction of propargylic compounds with iodine in the presence of readily available cadmium (II) acetate in some solvents was developed. The highest yields of iodoalkynes and iodoalkenes were recorded using DMSO as the solvent. An excess of the alkylpropargyl substrate unambiguously led to iodolkynes. By varying the reaction conditions using a twofold excess of iodine in DMSO, methanol or ethanol it was possible to achieve a one‐pot preparation of triiodoalkenes. The interaction of iodine with propargyl substrates could be represented in two ways: formation and further nucleophilic transformation of the iodonium complex under the influence of the acetate ion and generation of π‐coordinated species and elimination of acetic acid.

An efficient procedure has been proposed for the addition of iodine to the triple bond and substitution of the terminal hydrogen atom of 1-(prop-2-yn-1-yl)-1H-pyrazole in the presence of cadmium(II) acetate at room temperature. The solvent and reactant ratio have been optimized.

The reactions of nucleophilic addition of СН-acids to terminal alkynes under electrophilic catalysis with mercury(II) acetate were studied. As a result of mercury-demercuration reactions, the corresponding aromatic and linear derivatives were obtained. A method was proposed for the regeneration of the resulting amorphous mercury by reduction into mercury(II) acetate.