Doklady Chemistry最新文献

A one-pot synthesis of random multiblock copolymers of norbornene and cyclooctene was performed for the first time. It was shown that the first-generation Grubbs Ru–carbene complex enables the synthesis of these copolymers directly from monomers. The one-pot synthesis starts with the metathesis polymerization of norbornene, which has a markedly higher ring strain. Then cyclooctene polymerization takes place, being accompanied by interchain macromolecular cross-metathesis, to give the block copolymer structure. In comparison with the previously studied reaction of polynorbornene and polycyclooctene, the one-pot method affords copolymers with a higher molar weight at a lower catalyst consumption.

The review characterizes the role of the basic targets of antibacterial agents: efflux pumps, enzymes (DNA gyrases as a subclass of topoisomerases, homoserine transacetylase, various classes of sortases, aromatase, lipoteichoic synthase, polyketide synthase, pantothenate synthetase, acetyl-CoA carboxylase, sensory histidine kinase, kinase, cyclooxygenase, etc.), penicillin-binding protein, quorum sensing systems, and adhesins in significant biochemical processes of pathogen maintenance and virulence manifestation. It has been demonstrated that a chemical can exhibit the antimicrobial effect when it binds to protein molecules responsible for pathogenicity of a microorganism. The role of quinazolinone derivatives exhibiting high reactivity and stability in chemical processes and characterized by a wide spectrum of pharmacological activity, including antimicrobial activity with respect to various Gram-positive and Gram-negative bacteria, has been determined. It has been shown that structural changes induced by introducing various substituents contribute to a change in the degree of hydrophilicity and, as a result, determine a different degree of penetration of the drug through the cell membrane, the ability to form intermediate complex compounds stabilized by a system of hydrogen bonds, as well as by van der Waals and stacking interactions, with enzymatic targets, receptor regulatory proteins, and signaling systems of pathogen cells. The results of mathematical modeling of the mechanism of action of the compounds synthesized by the authors of the article are discussed. The possibility of creating a pharmaceutical with a pronounced antimicrobial activity by combining the quinazolinone core with various heterocyclic derivatives is assessed. The considered regularities are of practical importance for the researchers in the field of medicinal chemistry, organic synthesis, biotechnology, clinical pharmacology, and pharmaceutical chemistry and technology, whose efforts are aimed at designing a new drug.

In the course of synthesis of oligosaccharides related to fragments of the capsular polysaccharide of Haemophilus influenzae type e, reactions of 2-O-trifluoromethanesulfonate β-D-glucopyranoside derivatives with the azide anion were studied. The reactions gave products of both nucleophilic substitution and rearrangement accompanied by 6-membered pyranose ring contraction to a 5-membered ring through (O5–C2)-cyclization. The formation of these products was interpreted for the first time using quantum mechanical calculations.

3-Bromo- and 6-chloroquinolines or 2-bromo-1-methylbenzimidazole react with red phosphorus in the KOH/DMSO (Н₂О) system on heating (100–120°C, 3 h) to form in high yield the products of selective reduction (with retention of the aromatic heterocycle): quinoline or 1-methylbenzimidazole, respectively.

A simple and feasible approach to the synthesis of new amine derivatives of acridine based on the methodology of direct C–H functionalization has been developed. The inhibitory effect of the synthesized compounds toward cholinesterases and carboxylesterase as well as their antioxidant activity have been studied. A high anti-BChE activity has been shown for N-methylpiperazine derivative promising for further optimization to design on its basis new series of compounds efficient for the treatment of neurodegenerative diseases.

In order to search for new antibacterial and anticancer agents, the data of amphiphilic quaternary ammonium compounds (QAC) based on natural structures were analyzed and systematized over the past three years in this review. The analysis of publication is considered on the properties of QAS based on heterocyclic and pyridine alkaloids, alkylated phenols, terpenoids and steroids. The relationships between the structure of ammonium salts and their supramolecular self-assembly, biological activity, and cytotoxicity were tried to be revealed. In terms of synthetic ease of chemical modification, availability, biorelevance, and efficacy against strains of bacterial pathogens and antitumor activity, prospects for using natural platforms for extended trials have been identified.

A concept was proposed for integrated catalytic processing of organochlorine waste using self-organizing nickel-based catalysts. The process of carbon erosion of a bulk Ni–Cr alloy to form dispersed particles catalyzing the growth of carbon nanofibers was studied using 1,2-dichloroethane as an example. This approach was found to be universal and applicable to the processing of multicomponent mixtures of organochlorine compounds, including polyvinyl chloride production waste. The potential of using the carbon nanomaterial obtained by the waste processing for the production of polymer composites was discussed.

Ultra-high-molecular-weight polyethylene (UHMWPE) with an elevated melting point T_m of up to 144°C has been successfully fabricated by suspension polymerization initiated by Ziegler–Natta catalysts in a 1H,4H-octafluorobutane medium. This method allows one to efficiently perform the polymerization at a near-ambient temperature and a near-atmospheric ethylene pressure. The obtained polyethylenes have been characterized by IR spectroscopy, elemental analysis, and thermal analysis, and the melting points and degrees of crystallinity of the synthesized polymers have been found.

The review analyzes recent publications dealing with the search for new efficient desulfurization technologies, in particular, oxidative desulfurization using ionic liquids. This technology attracts attention due to its relatively mild conditions compared to hydrodesulfurization and its efficiency in removing heavy sulfur derivatives. Of special interest are solid hybrid compositions consisting of a support coated with an ionic liquid layer containing catalytically active centers. Examples of the use of such polyfunctional systems, simultaneously functioning as an adsorbent, extractant, and catalyst, for the oxidative desulfurization of model fuel and real oil feedstock are considered.

It has been shown that imidazole adds to the triple bond of 3-butoxypropyne under the action of catalytic amounts (5 mol %) of silver salts to give a mixture of α and β isomers: 1-(3-butoxyprop-1-en-2-yl)-imidazole and 1-[(Z)-3-butoxyprop-1-en-1-yl)]-imidazole.