Russian Chemical Bulletin最新文献

Ethyl 12-chlorosulfodehydroabietate was used in the first synthesis of hydroxysulfonamides containing monoethanolamine and phenylalaninol fragments in 98% and 95% yields, respectively. p-Toluenesulfonyl derivatives of these hydroxysulfonamides were found to react with potassium thioacetate to be converted to thioacetates. However, they underwent quantitative conversion to disulfides in the presence of trace amounts of pyridine. Both thioacetates and disulfides were oxidized with chlorine dioxide to sulfonyl chlorides in 90–96% yields.

An efficient regioselective synthesis of new water-soluble imidazo[2,1-b]thiazol-4-ium derivatives with potential biologically activity by the reaction of 1-methylimidazole-2-sulfenyl chloride with vinyl ethers was developed.

Products of transformations of methyl methacrylate and collagen were obtained in aqueous dispersions upon photocatalysis in the presence of series of various complex metal oxides of the metals: Na, K, Cs, Rb, Bi, V, Mo, Te, Ni, W, Mn, Co, Cu, and Nb. These oxides generate hydroxyl radicals in the aqueous dispersion. A grafted copolymer of methyl methacrylate on collagen was formed in methyl methacrylate-collagen dispersions only upon the photocatalysis with catalysts NaVMoO₆, KVMoO₆, and CsV_0.625Te_1.37O₆. In the other cases, trace amounts of methyl methacrylate homopolymer, a monomer of the new type (oxidation product of methyl methacrylate), and its polymer were formed, as confirmed by data acquired by scanning electron microscopy and NMR spectroscopy. In general, the directions of processes associated with transformations involving methyl methacrylate are observed, but the optimization of conditions to three-dimensional structures based on methyl methacrylate graft copolymers with collagen is reasonable for medical purposes only in the cases of three mentioned compounds.

A series of terpene α-chlorohydrins was synthesized in 44–89% yields by the reduction of the corresponding α-chloro ketones using NaBH₄. In turn, α-chloro ketones were synthesized from the secondary terpene alcohols by a one-pot procedure using the ClO₂—DMF oxidative-chlorinating system. α-Chloro ketones demonstrated significantly higher antifungal activity than the corresponding chlorohydrins and oxygen-containing terpenoids and in some cases their activity is comparable to or exceed the activity of the antifungal reference drugs fluconazole and ketoconazole.

Novel methacrylate-based molecular bottle-brush polymers containing ionene fragments, hydrophilic oligo(ethylene glycol) and hydrophobic alkyl groups, in the side chains were synthesized by the polymerization method via reversible addition—fragmentation chain transfer mechanism in organic solvents and characterized. The solubility in various solvents was shown for the synthesized molecular bottle-brushes, while the critical micelle concentrations and hydrodynamic sizes of the formed self-assembled aggregates were determined in aqueous solution. The influence of the characteristics of the polymers on the thermoresponsive and surface-active properties and the capacity of the polymer micelles toward pyrene (as a model of a low-molecular-weight hydrophobic drug) were studied.

A series of layered praseodymium tellurite halides of the general formula [Pr_12−x(TeO₃)₁₂][M^I_4+3xX₁₆] (M = K, Rb, Cs; X = Cl, Br) and the compounds [Pr₁₂(TeO₃)₁₂][Cd₆Cl₂₄] and [SrPr₄(TeO₃)₄][Cl₆] were prepared by the crystallization from reactive halide fluxes at 825–850 °C. The structures of the new compounds were determined by single-crystal X-ray diffraction analysis. The applied synthetic protocol leads to a significant improvement of both the yield and quality of the crystals. The crystal structures of the majority of the new compounds consist of praseodymium tellurite blocks of the composition [Pr_12−x(TeO₃)₁₂] interleaving with metal halide counterparts of the composition [M^I_4+3xX₁₆] or [Cd₆X₂₄]. The crystal structure of the new tellurite chloride [SrPr₄(TeO₃)₄][Cl₆] contains [SrPr₄(TeO₃)₄] layers. This compound completes the [SrLn₄(TeO₃)₄][Cl₆] structural family (Ln = Ce, Pr, Nd, Sm). When using binary fluxes based on alkali halides, sodium cations were not incorporated in the final products; the reactions using fluxes composed of cadmium and alkali halides afforded [Pr₁₂(TeO₃)₁₂][Cd₆X₂₄] as the major products. The use of fluxes based on heavier alkali halides (K, Rb, Cs) resulted in the formation of products, the structures of which exhibit the partial cation ordering between the metal tellurite and metal halide layers. The polytypism and the application of the modular approach to the description, classification, and prediction of novel structures of layered rare-earth tellurite and selenite halides are discussed.

The work presents a new approach to the synthesis of C/SiC composite fibers and nanocrystalline silicon carbide (SiC) with particle sizes of 50–100 nm. The method is based on coupled gas-solids reactions between silicon and carbon precursors using SiO gas, which enables the simultaneous production of composite fibers and high-purity nanocrystalline SiC within a single reaction volume. The phase composition, morphology, and elemental composition of the products were analyzed using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. It was shown that the synthesized β-SiC is characterized by high uniformity, purity, and the presence of stacking faults. The developed method allows for controlling the synthesis process and obtaining pure (free of residual silicon) nanocrystalline β-SiC, whose crystal structure is characterized by a comparatively low concentration of stacking faults, which are characteristic of nanocrystalline β-SiC.

The influence of the degree of preliminary graphitization of synthetic diamond powder on the efficiency of silicon carbide (SiC) formation on its surface during high-temperature silicidation by SiO gas was investigated. It is shown that the original and weakly graphitized diamond powders practically do not react with SiO at 1400 °C due to their high chemical inertness caused by sp³ hybridization of carbon. In the case of highly graphitized samples, the formation of nanocrystalline SiC was observed predominantly in areas where graphite layers formed on the surface of diamond particles. The average size of SiC crystallites was 15–20 nm. The obtained results demonstrate that preliminary graphitization is a necessary step for efficient silicidation of diamond powders with gaseous SiO.

The emergence of drug resistance in pathogenic strains and the associated rise in mortality have driven the need for new, highly effective antimycotics based on azole derivatives. New chiral hybrids comprising a 1-(2,4-dichlorophenyl)-2-(1H-1,2,4-triazol-1-yl)ethyl moiety and a monoterpene thiol with a 1,3-dioxolan-4-ylmethyl linker, structurally similar to the itraconazole and ketoconazole pharmacophores, were synthesized. The hybrids demonstrated high antifungal activity against both fluconazole-susceptible and fluconazole-resistant Candida albicans strains. The affinity of the synthesized compounds for a fungal enzyme, lanosterol-14α-demethylase (CYP51), was evaluated. This enzyme catalyzes a key step in the biosynthesis of ergosterol, a steroidal component that plays a critical role in maintaining the structural integrity and functional activity of fungal cell membranes.

Methyl analogs of lamellarins were synthesized in two steps via 1,3-dipolar cycloaddition of isoquinolinium ylides to nitrostyrenes ArCH=C(Me)NO₂ followed by lactone ring closure through ortho-MeO-substituent in the aryl fragment.