Vol 66, No 12 (2017)

The data on the synthesis methods, properties, and structural specific features of N-(silylmethyl)ureas are systematized.

The mechanisms of furan formation and the competitive reaction of 1,5-diketone formation from 1-mesitylbut-2-en-1-one (1a) and 1-phenylbut-2-en-1-one (1b) were studied using the B3LYP/6-311++G**//B3LYP/6-31+G* quantum chemical approach taking into account solvation effects in terms of the IEFPCM model. The addition to 1a of the ethynide ion to form β-acetylene enolate ion (2a) occurs with the activation energy ΔG^≠ = 13.3 kcal mol^–1, while the further intramolecular O-vinylation with the closure of 2a to the dihydrofuran cycle of the dihydrofuran carbanion is the rate-determining step in the reaction pathway of substituted furan formation needing the activation energy G^≠ = 19.5 kcal mol^–1. The alternative addition of the mesitylethenolate ion to 1a to form the 1,5-diketone carbanion is associated with a higher (by 3.4 kcal mol^–1) free activation energy than that of ethynide ion addition. In contrast, in the case of 1b, the addition at the C=C bond of the phenylethenolate ion rather than of the ethynide ion to form the 1,5-diketone carbanion is more preferable, since its activation free energy is 1.5 kcal mol^–1 lower. The quantum chemical calculation results are consistent with the experimental data.

For the purpose of investigation of the electronic structures of functionalized pyrroles with potential biological activity the electronic structures and ionization spectra of S-cis-(Z)-2-(2-formylethenyl)pyrrole (FP) were calculated by the propagator quantum chemical method. The calculations were performed using the third-order algebraic diagrammatic construction method (ADC(3)) for one-particle Green´s function (electronic propagator) and the 6–31G** basis set. Going from FP (possessing the intramolecular hydrogen bond H⋯O) to its conformation FPR (without H⋯O bonding), the O1s-ionization energy and the ionization energy of the σ-type lone electron pair orbital of the O atom decrease by ~0.2 eV, which is a consequence of stopping the electron density transfer from the O atom. A strong electron density transfer through the hydrogen bond from the O atom to the NH group occurs in the nitrogen core level ionization spectrum as evidenced by a lower N1s-ionization energy of FP (by ~0.7 eV ) compared to that of FPR. The valence shell ionization spectra of FP and FPR calculated using the ADC(3) method are characterized by a high density of the satellite states. The results obtained indicate that the electronic structures of the compounds of the considered class are characterized by pronounced effects of electron correlation.

The one-pot three-component synthesis of polyfunctional bis-heterocyclic triazoles, namely, previously unknown 1H-1,2,3-triazolylmethylidenepyrimidines and -1,3-dioxanes, was performed for the first time in moderate or high yields starting from element-substituted propynals, trimethylsilyl azide, and heterocyclic CH-acids at room temperature in aqueous medium.

A possibility of the O→C_sp 1,4-migration of the R₃Si group in silyl ethers of terminal acetylenic alcohols upon treatment with organolithium reagents (RLi) was studied. In the case of 3-trimethylsilyloxypropyne, depending on the nature of RLi, the heterolysis of the Si—O bond occurs either by the action of acetylide formed as a result of deprotonation with the formation of 3-trimethylsilylprop-2-yn-1-ol trimethylsilyl ether, or by the action of the metalation agent with the formation of propargyl alcohol. The realization of the O→C_sp 1,4-migration of the Me₃Si group requires the use of mild organolithium reagents (lithium hexamethyldisilazanide and diisopropylamide). Silyl ethers having steric hindrance at the carbon atom bonded to the reaction center or around the silicon atom do not react with the studied organolithium reagents.

The structures of paramagnetic complexes CuCl₂•L with L = HetCH₂Si(OCH₂CH₂)₃N [Het = pyrrol-1-yl (1), indol-1-yl (2), carbazol-9-yl (3), imidazole-1-yl (4), 3,5-dimethylpyrazol-1-yl (5), 1,2,4-triazol-1-yl (6), benzimidazol-1-yl (7), and 1,2,3-benzotriazol-1-yl (8)] were studied by the ESR and quantum chemical methods in terms of the density functional theory (DFT) approximation. The difference in structures of complexes CuCl₂•1—CuCl₂•8 is mainly determined by the nature of the five-membered heterocycle. The ESR spectra at room temperature are typical of the mononuclear complexes of Cu^II of axial symmetry with various types of distortions. In complexes CuCl₂•1—CuCl₂•3, narrow symmetric signals of zero-valent copper are recorded. These signals remain in the spectra for at least six months, which can characterize them as efficient stabilizing matrices of nanoparticles.

New organosilicon derivatives of dithizone with high sorption activity and nonselective metallochromic properties were synthesized. When they are modified, the possibility of increasing the selectivity of their metallochromic effect and prospects for using them as test systems are shown.

New cross-linked insoluble polyfunctional copolymers with triazole fragments and vinyloxy groups in the side chain were synthesized by radical copolymerization of 1-vinyl-1,2,4-triazole with diethylene glycol divinyl ether. The dependence of the sorption activity with respect to the gold ions in acidic solutions on their nature and concentration was studied. The copolymers obtained were found to possess high sorption activity; they efficiently extracted gold ions from solutions of complex composition.

New polymer nanocomposites containing iron oxide nanoparticles stabilized with a biocompatible copolymer of 1-vinyl-1,2,4-triazole with N-vinylpyrrolidone were produced. The synthesis was conducted using the method of chemical reduction of iron ions with hydrazine hydrate in an aqueous medium in the presence of a polymer matrix. The ESR spectroscopy data showed that the core—shell type nanoparticles were obtained. The core generally consistsed of zero-valence iron coated with an oxide shell. According to the data of transmission electron microscopy, the obtained polymer nanocomposites consisted of nanoparticles of mainly spherical shape with a diameter from 1 to 14 nm. Aggregates formed from individual stabilized nanoparticles of up to 75 nm in size (in most cases) were also observed. These aggregated particles were found to self-organize and form branched chains. Nanocomposites were characterized by a different particle-size distribution, which was determined by the initial ratio of the copolymer and the precursor of iron nanoparticles.

The mechanism of polysaccharide arabinogalactan sulfation was studied. Potassium persulfate in dimethyl sulfoxide was used as a sulfating agent. Sulfation of the biopolymer proceeds via its reaction with the SO₃—DMSO complex, which is formed upon the reduction of the persulfate anion in DMSO.

The specific features of the optical characteristics of spherical silver nanoparticles stabilized by polysaccharide matrices of galactomannan and carrageenan with a narrow size distribution were studied. The dependence of the surface plasmon resonance maximum and its width on the polysaccharide matrix type, the content of silver nanoparticles in the composite, the temperature, and the process duration was established.

(Chloromethyl)trichlorosilane reacts with 2,2-dimethylpropane-1,3-diol to produce α-carbofunctional heterocycles, 2-chloro-2-(chloromethyl)-5,5-dimethyl-1,3,2-dioxasilinane and 2,8-dichloro-2,8-bis(chloromethyl)-5,5,11,11-tetramethyl-1,3,7,9-tetraoxa-2,8-disilacyclododecane. The synthesized macroheterocycle is the first structurally characterized 1,3,7,9-tetraoxa-2,8-disilacyclododecane derivative.

To the article “Antitumor activity of carboplatin in the composition of a copolymer of lactic and glycolic acids,” by E. D. Nikolskaya, O. A. Zhunina, N. G. Yabbarov, V. A. Zenin, O. G. Tereshchenko, M. V. Fomicheva, M. B. Sokol, A. V. Lobanov, and E. S. Severin, Vol. 66, No. 10, pp. 1867–1872, October, 2017.

In the original international version of the article, seventh author’s name was omitted. In should be M. R. Faustova.