Vol 94, No 1 (2024)

In aqueous solutions of acetonitrile (1 vol%), the rate of oxidation of diethyl sulfide with sodium peroxoborate, Na₂[B₂(O₂)₂(OH)₄]∙6H₂O, in the pH range of 8.5–11 is significantly higher than the oxidation rate in water and exceeds the rate of reaction of Et₂S with hydrogen peroxide in the H₂O–MeCN system. The reaction order with respect to the substrate, which is close to zero, suggests that the limiting stage of the process is the reaction of peroxoborate anions with MeCN, leading to the formation of active boron peroxyimidates, which then react in a rapid stage with Et₂S.

The article analyzes publications that present the results of studies of modern approaches to the synthesis of new and known heterocycles with a pyrazole fragment, as well as syntheses aimed at expanding the library of compounds of this series from hydrazines, hydrazides, semi- or thiosemicarbazides, diazo compounds, hydrazonyl chlorides. Some examples are shown that use approaches to the synthesis of pyrazoles through multicomponent reactions involving amines and hydroxamic acid or an amine and enaminoketone. References are provided to publications that reflect the results of studies of the biological activity of these heterocycles, the use of certain metals as selective extractants, the possibility of obtaining metal complexes with their participation, as well as some photochemical transformations.

Upon condensation of 2 equiv. of 3R*,3aR*,8bS*-3-iodo-7-methyl-1,2,3,3а,4,8b-hexahydrocyclopenta[b]indole with 1 equiv. of glutaric or decanedicarboxylic acid dichloranhydride [N⁴,N^4′-di-(3R*,3aR*,8bS*,3′R*,3a′R*,8b′S*)- and N⁴,N^4′-di-(3aR*,3aR*,8bS*,3′S*,3a′S*,8b′R*)-3-iodo-7-methyl-1,2,3,3а,4,8b-hexahydrocyclopenta[b]indolyl]alkanediamides were synthesized. Their didehydrohalogenation to 3aR*,8bR*,3a′R*,8b′R*- and 3aS*,8bS*,3a′R*,8b′R*-1,3a,4,8b-tetrahydroanalogues was carried out by boiling these diiodides in piperidine. The presence of rotamerism in the products of dehydrohalogenation was shown, which is manifested by doubling the signals in the NMR spectra in different ratios. Nitration with trifluoroacetyl nitrate in CH₂Cl₂ yielded their 5,5′-dinitro analogs, which, when reacted with freshly prepared Fe(OH)₂, along with 5,5′-diamino derivatives, also formed 5-amino-5′-nitro-substituted products of incomplete reduction. When a nitro group or an amino group appears at the C⁵ and C^5′ carbon atoms of the cyclopenta[b]indole fragments, the doubling of the signals in the NMR spectra disappears. The interaction of a 5,5′-diamino derivative (n = 8) with decanedicarboxylic acid dichloride yielded a compound with 30 atoms in the macrocyclic ring.

The reaction of 3-[(amino-2-naphthyl)amino]-5,5-dimethylcyclohex-2-en-1-one with o-quinones provided previously unknown macrolactones of the oxonine series with naphthopyrazine fragments.

By fusing methyl picolinate with phenacyl bromides, the corresponding phenacyl salts were obtained, cyclization of which in acetic anhydride led to previously undescribed 3-aryl-1H-pyrido[2,1-c][1,4]oxazinium bromides. Reduction of the quaternary salts of methyl picolinate followed by acid hydrolysis leads to the alkaloid DL-baikiain.

Zirconium oxide coatings of various thicknesses were synthesized on the surface of plates of monocrystalline silicon and borosilicate glass by alternating pulsing of zirconium(IV) tert-butoxide and water vapors treatment. The effect of the matrix type and the coating thickness on surface morphology of the samples was investigated using atomic force microscopy. The concentrations of zirconium in the synthesis products were determined by X-ray spectral microanalysis and the growth constant of the zirconium oxide film on silicon was evaluated. Assumptions are made about the influence of the type of the matrix on the structure of the surface of the zirconium oxide layer.