Preparation of a chelating sorbent based on pyridylethylated polyethylenimine for recovering transition metal ions

A method was developed for preparing a chelating amino polymer, pyridylethylpolyethylenimine with maximal degree of substitution, by polymer-analogous transformations of branched polyethylenimine in reaction with 2-vinylpyridine. The ability of cross-linked pyridylethylpolyethylenimine with the degree of substitution of 0.32 to sorb Cu2+, Ni2+, Co2+, Zn2+, Cd2+, Mn2+, and Pb 2+ ions present simultaneously in solution was evaluated. In an ammonium acetate sorption system (pH 3.5-4.0), the sorbent selectively interacts with Cu(II) ions. © 2013 Pleiades Publishing, Ltd

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

Reactions of 3-phenyl-1,2,4-triazine with some C-nucleophiles

Dimedone is added at C(5) of 3-phenyl-1,2,4-triazine to give stable dihydro derivative. Its reaction with 1-aryl-3-methylpyrazol-5- ones proceeds with fragmentation affording 1,1,2,2-tetrakispyrazolylethane and amidrazone derivatives. © 2013 Mendeleev Communications. All rights reserved

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

New opportunities for the synthesis of quinoxaline-substituted heterocyclic and aryl moieties

6.7-Difluoroquinoxaline (I) reacted with dimedone, indandione, and 3-methyl-1-phenylpyrazol-5-one in DMSO solution in the presence of acid to form mono-substituted products IIa - c. Heating I with resorcinol in EtOH in the presence of acid gave resorcinol derivative IId. 6.7-Difluoroquinoxaline in the presence of base reacted with 3-methyl-1-phenylmethylpyrazol-5-one to form dipyrazolylmethane III and tetrapyrazolylethane derivative IV. Heating products IIa - c with N-methylpiperazine produced 7-methylpiperazine derivatives Va - c of 2-substituted quinoxalines. © 2013 Springer Science+Business Media New York

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

Consecutive S N H and Suzuki-Miyaura cross-coupling reactions-an efficient synthetic strategy to pyrimidines bearing pyrrole and indole fragments

The combination of the Suzuki-Miyaura cross-coupling and nucleophilic aromatic substitution of hydrogen reactions is a versatile tool for the syntheses of 4-(1R-pyrrol-2-yl)-and 4-(1R-indol-3-yl)-5-(hetero)aryl-substituted pyrimidines from commercially available 5-bromopyrimidine. The S N H [AE, (addition-elimination)] and S N H [AO, (addition-oxidation)] reactions of 5-bromopyrimidine with pyrroles and indoles were studied by gas chromatography-mass spectrometry. The structures of the intermediate σ H adducts as well as the pyrrole-(hetero)arylpyrimidine and indole-(hetero)arylpyrimidine dyads were established for the first time by X-ray crystal structure analysis. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim