Volume 87, Nº 8 (2017)

Correlation equations describing the influence of inductive, resonance, polarizability, and steric effects of the substituents on the parameters of IR, NQR, NMR, and Mössbauer spectra as well as ionization and activation energies have been considered for 13 reaction (indicator) series. Using the obtained equations, we have calculated the earlier unknown polarizability constant of iodine substituent (σ_α =–0.71). The relation between the σ_α constant of substituent X and polarization of atoms of X has been found for the CH₃X (H, F, Cl, Br, I) series.

Palladium isocyanide complex modified in situ by addition of benzohydrazide as nucleophile was shown to catalyze Sonogashira reactions of phenylacetylene with iodobenzenes in refluxing ethanol in the presence of potassium carbonate. The reactions were complete in 2 h, and neither preliminary degassing nor protection from atmospheric moisture and oxygen was necessary. The yields of the cross-coupling products, unsymmetrical diarylacetylenes were only slightly lower than those obtained with the preliminarily prepared catalyst. The proposed procedure was used to synthesize a series of diarylacetylenes containing both electrondonating and electron-withdrawing substituents in the benzene rings.

Epoxidation of β-pinene with 35–38% aqueous hydrogen peroxide in a new catalytic system containing manganese sulfate, salicylic acid, sodium bicarbonate and polar solvent (DMF, acetonitrile, methanol) is described. The method of quantitavive determination of β-pinene and its epoxide is developed.

Carbanions derived from ethyl 3-oxobutanoate and diethyl malonate reacted with an equimolar amount of N-chloro-N-ethylethanamine, N-chloromorpholine, or N-chloropiperidine to give diethyl 2,3-diacetylbutanedioate and tetraethyl ethane-1,1,2,2-tetracarboxylate in 68–83% yield. The possibility of heterocoupling of ethyl 3-oxobutanoate and diethyl malonate carbanions by the action of N-chloro-N-ethylethanamine and the effect of the molar reactant ratio on the selectivity of oxidative homo- and heterocoupling were studied.

Reactions of methyl 3,4,6-trioxoalkanoates (3,4-dihydroxy-6-oxo-2,4-alkadienoates) with mixtures of aromatic aldehydes and arylamines or with the corresponding N-(arylmethylidene)anilines afforded methyl (4-alkanoyl-1,5-diaryl-2-hydroxy-3-oxo-2,3-dihydro-1H-pyrrol-2-yl)acetates. The product structure was discussed on the basis of their IR, ¹H NMR, and mass spectra and X-ray diffraction data, and their antimicrobial activity against Staphylococcus aureus P-209 and Escherichia coli M₁₇ was evaluated.

o- and p-Hydroxybenzohydrazides reacted with various unsaturated aromatic aldehydes to give the corresponding N′-(hydroxybenzoyl)hydrazones. Inhibitory activity of the obtained hydrazones against cathepsin E was evaluated.

N-(1-Naphthyl)furan-2-carboxamide was synthesized by the coupling of naphthalen-1-amine with furan-2-carbonyl chloride in propan-2-ol and then treated with excess P2S5 in anhydrous toluene to obtain the corresponding thioamide. The latter was oxidized with potassium ferricyanide in an alkaline medium by the Jakobson procedure to synthesize 2-(furan-2-yl)benzo[e][1,3]benzothiazole which was subjected to electrophilic substitution reactions: nitration, bromination, formylation, and acylation.

Bromination of prop-2-enyltributyl- and -triphenylphosphonium bromides affords the products of addition to the double bond. The structure of the triphenylphosphonium adduct was established by X-ray diffraction analysis. The latter is formed also by radical bromination of prop-1-enyltriphenylphosphonium bromide. The chlorination of prop-1- and 2-enyltriphenylphosphonium bromides leads to the formation of 3-chloroprop-1-enyltriphenylphosphonium bromide.

1,1-Dimethoxy-3-inoisoindoline was reacted with 3-alkyl-1,3,4-thiadiazoline to obtain macroheterocyclic compounds containing three isoindole fragments and one 3-alkyl-1,3,4-thiadiazoline fragment. The structure and composition of the synthesized compounds were studied by means of electronic absorption, IR, and ¹H NMR spectroscopy, and well as mass spectral ana elemental analyses.

Isocyanide zinc complexes [ZnX₂(CNR)₂] (X = Cl, Br, I; R = Xyl, Cy, Bu^t) have been prepared via the interaction of the corresponding zinc halides ZnX₂ and isocyanide CNR in toluene at 100°C (yield 64–77%) and characterized by the data of elemental analysis, mass spectrometry, IR and NMR spectroscopy, and X-ray diffraction analysis. The zinc complexes [ZnBr₂(CNR)₂] (R = Xyl, Сy) have been used as catalysts for the synthesis of formamidines R¹N=CHNR₂² [R¹ = Xyl, Сy; R₂² = Et₂, (CH₂)₄, (CH₂CH₂)₂NMe, Me + CH₂Ph] from isocyanides CNR¹ and secondary amines HNR₂² in bulk (yield 92–98%).

Integral enthalpies of dissolution Δ_solH^m of DL-α-alanyl-DL-α-alanine in aqueous solutions of glycerol, ethylene glycol, 1,2-propylene glycol, and 1,3-propylene glycol at the concentration of the organic component up to 0.33 molar fraction have been determined by calorimetry. Standard enthalpies of dissolution (Δ_solН⁰) and the transfer (Δ_trН⁰) of the dipeptide from water to aqueous solutions of the polyhydric alcohols have been calculated. The calculated enthalpic coefficients of pairwise interactions of DL-α-alanyl-DL-α-alanine with polyhydric alcohols are positive. The influence of the position of hydroxy groups in the polyhydric alcohol molecule on the enthalpic parameter of the interaction with the dipeptide has been revealed. The effect of various types of the interaction in the solution and structural features of biological molecules and the cosolvent on the enthalpic parameters of the dissolution has been analyzed.

Equilibrium sorption of saponin from Quillaja saponaria Molina with chitosan has been analyzed. The shape of the sorption isotherm is determined by the competing processes of the glycoside association in the solution and its absorption with chitosan, as evidenced by the calculated absorption and association energies and the curves of chitosan dehydration accompanying the saponin sorption. Analysis of the chitosan surface during the saponin sorption by means of atomic force microscopy has revealed the structure-morphology features depending on the glycoside concentration in the external solution.

The chemical assembly of a titanium oxide coating on a regular microporous silica surface by the atomic layer deposition method was considered. The change in the pore structure of the matrix was estimated, and a model of the coating formation in microporous materials was proposed.

A series of carbazole–thiophene oligomers linked at the 3,6-positions of the carbazole fragment of 4,4′-bis(carbazol-9-yl)biphenyl (CBP) and 4,4′-bis(carbazol-9-yl)-2,2′-dimethylbiphenyl (CDBP) with systematically elongated molecular lengths were synthesized via the Suzuki–Miyaura and Ullmann coupling reactions. Their electronic properties were studied by UV-Vis, cyclic voltammetry, and theoretical calculations. The coupling of CBP and CDBP with thiophene and bi- and terthiophene residues stabilized the HOMO and LUMO energy levels. The absorption and emission spectra exhibited a gradual red shift. The compounds with oligothiophene units had greatly decreased band gaps compared with CBP and CDBP. Therefore, these units may be introduced into the backbone of π-conjugated small molecules to develop new materials with low band gaps that may have potential applications in optoelectronics.

Three-component reaction of 4-hydroxy-6-methylpyran-1-one with aromatic aldehydes and cyclic-1,3-diketone catalyzed by ZnO nanoparticles under solvent-free conditions leads a simple and efficient one-pot synthesis of pyrano[4,3-b]chromene-1,9-dione derivatives with high yields. The method has other advantages such as operational simplicity, short reaction time and environmental safety.

Objectives of the current study were synthesis, spectral characterization and biological screening of sulfanilamide derived Schiff bases and their metal based compounds. Sulfanilamide Schiff bases (L¹–L³) were synthesized by condensation of 4-aminobenzenesulfanilamide with 1-(furan-2-yl)ethanone, 1-(thiophene-2-yl)-ethanone, and 1-acetylindoline-2,3-dione. The ligands were used for preparation of their Co(II), Ni(II), Cu(II), and Zn(II) complexes by using metals chlorides in metal: ligand (1: 2) molar ratio. All metal chelates had octahedral geometry with bidentate ligands. The ligands and their metal complexes were characterized by physical, spectral and analytical data, and screened for in-vitro antibacterial activity against six bacterial pathogens (Escherichia coli, Shigella flexneri, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus, and Bacillus subtilis) and for in vitro antifungal activity against six fungal pathogens (Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani, and Candida glabrata). The results of antimicrobial studies revealed that the ligands activity was significantly increased upon chelation.

Fe₃O₄ magnetic core covered by zirconia shell bearing sulfonic acid groups (Fe₃O₄@ZrO₂–SO₃H) was prepared and used as an efficient acidic catalyst in the synthesis of thiazole derivatives by the reaction of acyl chloride with ammonium thiocyanate, amino acids and alkyl bromides. Fe₃O₄@ZrO₂–SO₃H exhibited high catalytic activity in the synthesis of thiazole derivatives. This new catalytic method for thiazole derivatives provided rapid access to the desired compounds in high yields in water media upon refluxing followed by a simple work-up procedure. The developed method is a significant improvement of the currently available synthetic approaches to thiazole derivatives.

A series of new 1,2,3-triazole/flavone hybrid heterocycles were synthesized from 6-amino flavone via key intermediate N-propargyl flavone 6 by adopting the Sharpless Click reaction. Copper(I) catalyzed 1,3-dipolar cycloaddition reaction that gave products in high yields. All the synthesized compounds were screened for their in vitro antiproliferative activity against four human cancer cell lines, HeLa (cervical cancer cell line), MIA PaCa (pancreatic cancer cell line), MDA-MB-231 (breast cancer cell line), and IMR 32 (neuroblastoma cancer cell line). Compounds 7a, 7b, 7d, 7g (GI₅₀ = 0.01–0.68 μM) demonstrated promising antiproliferative activity.

6-Methyluracil derivatives containing a gem-dichlorocyclopropane and a 1,3-dioxolane fragments were synthesized for the first time. The condensation of 6-methyluracil with chloromethyl derivatives gives a mixture of N¹- and N³-monosubstituted products, and the profound N-alkylation of this compound provides disubstituted uracils. The structure of the synthesized compounds was studied by H¹ and ¹³С NMR spectroscopy and their relative antioxidant activity was evaluated by luminol-dependent chemiluminescence measurements.

Convenient methods of synthesis of functionalized phosphonic acids and their trimethylsilyl esters containing quinuclidine, adamantine, and bornane (camphane) moieties, involving reactions of tris(trimethylsilyl) phosphite with quinuclidin-3-one and its carbocyclic analogs.

Dehydrocondensation reactions of silicon hydrides catalyzed by the rhodium(III) complex [RhCl₃(Me₂SO)₃] in the absence of the second substrate were studied. It was found that the complex [RhCl₃(Me₂SO)₃] catalyzed the dehydrocondensation reaction with the formation of compounds containing siloxane bonds. Analysis of NMR spectra has shown that the reaction of [RhCl₃(Me₂SO)₃] with silicon hydride includes sequential desoxygenation of sulfoxide ligands to sulfide ligands with the complex [RhCl₃(Me₂S)₃] formation.

Kinetics of isoleucine chemisorption on the modified silica surface involving an amide bond formation was studied. The grafted amino groups acting as chemisorption sites are uniformly distributed with respect to the activation energies. The reaction kinetics obeys the Roginsky–Zeldovich equation.