Vol 93, No 4 (2023)

The one-pot synthesis of N -substituted α,β-dehydrotyrosyl dipeptides was carried out by the azlactone method. The target dipeptides were obtained in good yields (53-79%). From the latter, 2,3,5-trisubstituted 4-imidazolones were obtained using 1,1,1,3,3,3-hexamethyldisilazane as a dehydrating agent. It was found that in the case of β-alanine-containing peptides, abstraction of the methyl ester of acrylic acid and the formation of 2,5-disubstituted 4-imidazoline were observed. Antiradical and anticholinesterase properties of the synthesized compounds were studied. Docking analysis was carried out for both some dipeptides and imidazole-4-ones.

The reaction of arylmethylidenecyanoacetic esters with N -arylamides of malonic acid led to the formation of previously unknown diethyl 6-amino-1,4-diaryl-2-oxo-1,2,3,4-tetrahydropyridine-3,5-dicarboxylates in 15-83% yields. Antibacterial activity of some obtained compounds was studied.

The optimal conditions for the oxidation of the methylene group in 4-ethyl-3-methylcinnoline to the corresponding ketone, 3-methyl-4-acetylcinnoline, were selected. It was shown that preliminary deposition of 4-ethyl-3-methylcinnoline on some inorganic substrates has a significant effect both on the selectivity of the oxidation of only the methylene group and on a high degree of conversion to the target product.

The reactions of hydrogermylation of allylsilanes and -germanes R₃MAll (M = Si, Ge; R = Cl, EtO, Me) by hydridgermanes R₃GeH (R = Cl, Me) and trichlorogermane ether 2Et₂O·HGeCl₃ were studied. It has been established that small amounts of mono- (β- and γ-adducts) and double germylation products and, mainly, polymers are formed in reactions with ether. During hydrogermylation of Me₃SiAll with trichlorogermane, insignificant amounts of β-adduct were recorded, but mainly in the entire series of experiments with Cl₃GeH, γ-adducts are formed. In the catalytic reactions of allylsilanes and -germanes with trimethylgermane, exclusively γ-adducts are formed regardless of the framing of silicon and germanium atoms. A scheme of the possible course of the studied reactions is proposed. The identification of synthesized compounds was carried out using the methods of gas-liquid chromatography, ¹Н, ¹³С NMR spectroscopy and chromatography-mass spectrometry

A method for the synthesis of 4,5-diphosphorylated 1,2,3-triazoles has been developed, and the extraction of U(VI), Th(IV), and lanthanides(III) from nitric acid solutions by them was studied. A synergistic effect was found in the extraction of metal ions with mixtures of 4,5-diphosphorylated 1,2,3-triazoles and dinonylnaphthalenesulfonic acid. The stoichiometry of the extracted complexes was determined, and the influence of the structure of the extractant and the concentration of HNO₃ in the aqueous phase on the efficiency of the extraction of metal ions into the organic phase was considered. It was established that 4,5-diphosphorylated 1,2,3-triazole with the octyl substituent at nitrogen atom has the highest extraction ability with respect to actinides and lanthanides in nitric acid media.

Thermal stability of N -alkylpyridinium tetrachloroferrates(III) [C₅H₅NR]FeCl₄ [R = C₄H₉, (CH₂)₃CN, CH₂C₆H₅, C₈H₁₇, C₁₀H₂₁] in air in the range of 25-600°C was studied, as well as the thermal stability of N -alkylpyridinium chlorides. The equivalent electrical conductivity of N -alkylpyridinium tetrachloroferrates(III) in acetonitrile solution at 25°C was investigated. The ionic association constants K _a , the limiting molar electrical conductivity (λ₀) and the standard Gibbs energy of the association (Δ G °) in acetonitrile solutions were calculated based on conductometric data by the Lee-Wheaton method.

DFT CAM-B3LYP/6-311++G(d,p) and CAM-B3LYP/6-311++G(d,p)/SDD calculations showed that the polydentate amidinyltetramethoxycarbonylcyclopentadienyl ligand and its Hg(II) and Tl(I) complexes are the most stable in the form of ylide isomers, in which the hydrogen or metal atom is bonded to the terminal nitrogen atom of the amidinium fragment and in the case of metal complexes, it is additionally coordinated by the π -system of the cyclopentadiene ring. Alternative isomers in which hydrogen or metal atoms are bonded to carbon atoms of the cyclopentadiene ring or to carbonyl oxygen atoms of methoxycarbonyl substituents are energetically less stable at Δ E _ZPE = 4.1-15.1 kcal/mol.

A wuestite phase metastable at room temperature in the form of a whisker conglomerate was found on the surface of nanoporous iron obtained by electrochemical dealloying (selective anodic dissolution of a less noble metal) of ferromanganese. The features of the further oxidation of iron by TG-DSC and Х-ray phase analysis with a temperature sweep were studied. A wide range of coexistence of three forms of iron oxides and relative stability of the magnetite phase up to 900°C were described.

Structural and thermodynamic characteristics of donor-acceptor complexes LA·E′H₂EH₂·LB(E = B, Al, Ga; E′ = P, As, Sb; LB = SMe₂, NMe₃);LA- Lewis acids of group 13 elements ER₃ (E = B, Al, Ga; R = H, Me, F, Cl, Br, I, C₆F₅) and transition metal carbonyls Fe(CO)₄, M(CO)₅, (M = Cr, Mo, W), CpMn(CO)₂ were computed by quantum chemical B3LYP-D3/def2-TZVP method. It is shown that removal of the Lewis base is less endothermic than removal of Lewis acid. Stability trends of the complexes depending on group 13/15 elements and Lewis acids were established. Tungsten pentacarbonyl has the highest stabilization effect.