Finitely presented wreath products and double coset decompositions

We characterize which permutational wreath products W^(X)\rtimes G are finitely presented. This occurs if and only if G and W are finitely presented, G acts on X with finitely generated stabilizers, and with finitely many orbits on the cartesian square X^2. On the one hand, this extends a result of G. Baumslag about standard wreath products; on the other hand, this provides nontrivial examples of finitely presented groups. For instance, we obtain two quasi-isometric finitely presented groups, one of which is torsion-free and the other has an infinite torsion subgroup. Motivated by the characterization above, we discuss the following question: which finitely generated groups can have a finitely generated subgroup with finitely many double cosets? The discussion involves properties related to the structure of maximal subgroups, and to the profinite topology.Comment: 21 pages; no figure. To appear in Geom. Dedicat

Synthesis, X-ray crystal structure and antimycobacterial activity of enantiomerically pure 1-ethyl-2,3-dicyano-5-(het)aryl-6-hetaryl-1,6- dihydropyrazines

The Petasis reaction of 6-alkoxy adducts of 1-alkyl-2,3-dicyano-5- arylpyrazinium salts with aromatic boronic acids, such as 2-thienylboronic, 2-furanylboronic and 3-thienylboronic acids, or their benzo analogs in dichloromethane proceeds smoothly at room temperature with the formation of the corresponding 5-aryl-6-hetaryl substituted 1,6-dihydropyrazine derivatives. All dihydropyrazines were separated as pure enantiomers by chiral HPLC, and their absolute configurations for each pair of enantiomers have been determined by X-ray analysis. Individual enantiomers were screened in vitro for their antimycobacterial activities against Mycobacterium tuberculosis H37Rv, avium, terrae and extensively drug-resistant and multi-drug-resistant strains isolated from tuberculosis patients in Ural region (Russia). It has been shown that several compounds exhibit a good level of antituberculosis activity compared to the reference drugs. © ARKAT-USA, Inc

Microwave-assisted palladium-catalyzed C-C coupling versus nucleophilic aromatic substitution of hydrogen (SN H) in 5-bromopyrimidine by action of bithiophene and its analogues

5-Bromopyrimidine reacts with 2,2′-bithiophene, [2,2′:5′, 2″]terthiophene and 2-phenylthiophene in the presence of a palladium catalyst to give 5-(het)aryl substituted pyrimidines due to the palladium-catalyzed aryl-aryl C-C coupling. However 5-bromo-4-(het)aryl- pyrimidines have been prepared from the same starting materials through the SN H-reaction catalyzed by a Lewis acid. Conditions for both types of reactions were optimized. All components of the reaction mixtures, including by-products, have been elucidated by gas-liquid chromatography/mass- spectrometry. Evidence for the structure of 4- and 5-bithiophenyl-substituted pyrimidines has first been obtained by means of X-ray crystallography analysis. Molecular orbital calculations (TDDFT), as well as the redox and optical measurements for all new compounds have also been performed. © 2013 Elsevier Ltd. All rights reserved

Kinetic Resolution of Racemic 2-Aryloxy Propionyl Chlorides Using Enantiopure (S)-3,4-Dihydro-3-methyl-2H-[1,4]benzoxazines

Stereoselectivity in the mutual kinetic resolution (KR) of racemic 3,4-dihydro-3-methyl-2H-[1,4]benzoxazines and racemic 2-aryloxy propionyl chlorides was studied. Based on the results obtained, preparative methods for single enantiomers of a series of 2-aryloxy propionic acids via acylative KR of their racemates with enantiopure (S)-3,4-dihydro-3-methyl-2H-[1,4]benzoxazines have been proposed. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, WeinheimThe work was financially supported by the Russian Science Foundation (grant 19‐13‐00231, in the part of studying mutual kinetic resolution) and the Russian Foundation for Basic Research (grant 18‐33‐00027_mol_a, in the part of preparation of enantiomers of 2‐aryloxy propionic acids). Analytical studies were carried out using equipment of the Centre for Joint Use “Spectroscopy and Analysis of Organic Compounds” at the Postovsky Institute of Organic Synthesis, Russian Academy of Sciences (Ural Branch

INVESTIGATION OF MODIFIED CEDAR NUT SHELL-BASED SORBENTS [ИССЛЕДОВАНИЕ МОДИФИЦИРОВАННЫХ СОРБЕНТОВ НА ОСНОВЕ СКОРЛУПЫ КЕДРОВОГО ОРЕХА]

The investigation was carried out to establish influences of thermal, chemical and thermochemical modifications on compositions of functional groups of the sorbents based on nut shells of the Siberian cedar (Pinus sibirica) and their physical and chemical properties. Samples of natural cedar nut shells (CNS) were thermally-modified at T=300 °С and analyzed by the methods of potentiometric titration and Fourier-transform infrared spectroscopy. It has been established that thermally-modified CNS possess 1.5-1.7 and 2.3-4.3 times as many hydroxyl and carboxyl groups in the constitution of sorbents grading 0.1-0.5 and 0.55-0.75 mm, respectively, as natural CNS. Chemical modification was carried out in nitric acid solutions with various concentrations (0.5-5n). It has been shown that being treated with 5n HNO3, the samples grading 0.55-0.75 mm possess 3.5 times as many carboxyl groups as natural CNS, while the samples grading 0.1-0.5 possess an increased number of hydroxyl groups only. Thermochemical modification was carried out in 2 stages: first, firing at a temperature of 300 °С, then chemical modification in HNO3 solutions with various concentrations. It has been revealed that this modification results to increasing predominantly hydroxyl groups in the constitution of carbon sorbents. The isotherm of sorption of copper (II) ions by the samples of modified CNS describes microporous solids with a relatively small outer surface, whereas the sorption isotherm of zinc (II) ions describes polymolecular adsorption onto both porous and macroporous adsorbents. The investigation has revealed that the sorbents being chemically and thermochemically modified with 5n nitric acid are most effective to extract copper ions. © 2023 Altai State University. All rights reserved

Preconcentration and photometric determination of lead

It has been shown that Sulfarsazen and 1-(2-hydroxy-5-nitrophenyl)-3-ethyl-5-(2-benzoxazolyl)formazan (Formazan VIII) can be used for the photometric determination of lead and give identical results at a specified significance level. The detection limits attained with the use of Sulfarsazen and Formazan VIII are 0.2 μg/mL and 0.16 ng/mL, respectively, and the latter reagent provides a better precision of determination. © 1997 MAHK Hayka/Interperiodica Publishing

Structure and characteristics of chitosan cobalt-containing hybrid systems, the catalysts of olefine oxidation

Cobalt-containing hybrid organo-inorganic materials based on the chitosan-SiO2, chitosan-Al2O3, and chitosan-cellulose systems were obtained. The surface structure and processes that occur during the formation of metal-containing materials, the catalytic properties of which were studied in the oxidation reactions of alkene, were investigated by EPR spectroscopy using a stable pH-sensitive nitroxyl radical, 4-dimethylamino-2-ethyl-5,5-dimethyl-2-(pyridin-4-yl)-2,5-dihydro-1H-imidazole- 1-oxyl, as the adsorbed probe molecules. © 2011 Pleiades Publishing, Ltd