Vol 65, No 2 (2016)

Homogenous and heterogeneous palladium catalysts with functionalized izoxazole and isothiazole ligands were developed for the cross-coupling reactions. The catalysts possessed high activity and were suitable for the repeated use. Compared with commonly used organic solutions, application of water and its mixtures with methanol as a reaction medium significantly intensifies catalysis with no side being formed. The obtained results are promising for the development of effective and ecologically friendly technologies of synthesis of important compounds such as polyfunctional biaryls, arylated olefins, acetylenes and their heterocyclic analogs.

The results of many-year research aimed at the development of domestic osteotropic diagnostic and therapeutic radiopharmaceuticals (RPhs) are surveyed. The RPhs developed at the State Scientific Center" Burnazyan Federal Medical Biophysical Center”, Federal Medical Biological Agency of Russia that are used in everyday clinical practice of Russian nuclear medicine departments are considered.

Online resources (PASS Online, SuperPred, SwissTargetPrediction and DRAR-CPI) for the prediction of biological activity of organic compounds from their structural formulas were considered. Based on a test set of drugs approved by 2014, the accuracies of predictions were compared. The four web resources can be arranged with respect to the quality of prediction (sensitivity, S) as follows: SwissTargetPrediction (S = 0.37) < DRAR-CPI (S = 0.41) < Super-Pred (S = 0.53) < PASS Online (S = 0.95). A conclusion was made that PASS Online employs superior machine learning algorithms based on MNA descriptors and Bayessian classifier in contrast to the similarity-based methods used in SuperPred and SwissTargetPrediction or the molecular docking methods used in DRAR-CPI. Possible reasons for the low prediction quality of SuperPred, SwissTargetPrediction, and DRAR-CPI are discussed and the development perspectives of this area of computational chemistry are given.

The mechanism of formation of 1,5-diketone, a key intermediate in the stereoselective assembly of 2,3,4-trimethyl-7-methylidene-1,5-di(thiophen-2-yl)-6,8-dioxabicyclo[3.2.1]octane, and the conformational structures of the reagents and products were studied by quantum chemical calculations at the MP2/6-311++G**//B3LYP/6-31G* level of theory with solvent effects treated within the polarizable continuum model. The activation barrier for the addition of the 1-oxo-1-(thiophen-2-yl)propan-2-ide ion (1), which is generated from 1-(thiophen-2-yl)propan-1-one, to acetylene is 15.2 kcal mol^–1. The reaction affords β,γ-unsaturated ketone. The subsequent addition of carbanion 1 to the C=C double bond of the resulting β,γ-unsaturated ketons yields 1,5-diketone and occurs with insignificant (less than 1 kcal mol^–1) activation barrier.

Density functional calculations (DFT) of a structure of dendrimer G1-4S-Bu (Si₅C₂₀H₁₃₂S₄) and its complexes with one, two, three, and four molecules of CuCl₂ have been carried out for the first time. The geometric structures of the complexes and spin-density distribution have been determined. For the studied complexes the states with maximum multiplicity are the most favorable. The interaction energies of the dendrimer G1-4S-Bu with CuCl₂ molecules have been calculated. It has been demonstrated that the formation of complexes with one or two molecules of CuCl₂ is the most favorable under standard conditions, which is consistent with the experimental data. Paramagnetic centers exist in all four studied complexes, and the unpaired electron is «localized» in four atoms: Cu, S, Cl, and Cl.

A potentiometric method was proposed for the determination of rate constants for peroxyl radical generation using the reduced form of the metal in the complex. The kinetics of the thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride was studied. The requirements for an electron donor (reactant) were formulated. The iron(ii) complex with EDTA, the iron(ii) complex with o-phenanthroline, and potassium hexacyanoferrate(ii) were used as reactants. The rate for peroxyl radical generation and the generation rate constant (the latter turned out to be (0.92±0.06)•10^–6 s^–1) were calculated. The studies were carried out for different temperatures and concentrations of the initiator and complex.

The supported bimetallic Fe—Pd/SiO₂ catalysts with the different Fe (0.025—8 mass.%) and Pd (0.05—3.2 mass.%) loadings were synthesized by the incipient wetness impregnation of support. The samples were heat-treated under different conditions (calcination in air at 240—350 °C or reduction in an H₂ flow at 400 °C). The X-ray phase analysis revealed the formation of Pd⁰, α-Fe₂O₃ and Fe₃O₄ phases after calcination of the samples at 240—260 °C. The reduction of the calcined Fe—Pd samples in an H₂ flow at 400 °C enables the formation of Fe⁰ nanoparticles of size 17—20 nm. The synthesized catalytic systems were studied in the selective hydrogenation of phenylacetylene at room temperature and atmospheric pressure in a solvent (ethanol, propanol). The catalytic properties of the Fe—Pd catalysts depend on the nature of solvent, catalyst composition, and thermal treatment conditions. The application of the Fe—Pd bimetallic catalysts with a low Pd loading of 0.05—0.1 mass.% made it possible to reach the high activity and selectivity to styrene (91%) at the complete conversion of phenylacetylene.

A highly selective coupling of azines with aromatic nucleophiles (S_N^H-reactions) in the presence of a heterogeneous oxidation system O₂/CdS/TiO₂ upon exposure to daylight was accomplished.

Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.

The liquid-phase epoxidation of allyl chloride in methanol with aqueous solution of hydrogen peroxide was conducted in the presence of extruded titanium containing silicalite and the physico-chemical features of the process were investigated. The effect of the amount of solvent, the initial ratio of the allyl chloride to hydrogen peroxide and the temperature of the process on the yield of the target product (epichlorohydrin) and by-products (3-chloro-1,2-propanediol and 3-chloro-1-methoxypropanol-2) was studied. Based on the obtained results, the optimum conditions of synthesis of epichlorohydrin for a laboratory scale continuous setup were recommended.

Aminomethylation of 4,4-bis(nitrooxymethyl)oxazolidin-2-one and 4,4-bis(chloromethyl)-oxazolidin-2-one utilizing primary amines as the amino components yielded 6,7a-substituted tetrahydroimidazo[1,5-c]oxazol-3-ones.

New ruthenium carbene complexes with chelating N- and S-benzylidene ligands were synthesized by the reactions of second- and third-generation Grubbs catalysts with ortho-vinylbenzyl-substituted amines or sulfides. These complexes were shown to exhibit catalytic activity in ring-opening metathesis polymerization and ring-closing metathesis.

A number of copoly(arylene ether ketones) containing the phenolfluorene and bisphenol A fragments were synthesized. By the example of these compounds, it was shown for the first time that the effect of reversible electronic switching can exhibit in the copolymer films even if this effect is absent in the corresponding homopolymer films.

A series of halogen substituted 6-azolylmethyl-7-benzylidenespiro[4.5]decan-6-ols were obtained from spiro[4.5]decan-6-one in three steps: Claisen—Schmidt condensation with substituted benzaldehydes, conversion of 7-benzylidenespiro[4.5]decan-6-ones to oxiranes by reaction with dimethylsulphonium methylide followed by ring opening of oxiranes with 1,2,4-triazole or imidazole. In vitro testing of fungicidal activity of synthesized compounds against seven phytopathogenic fungi showed, that a number of compounds are more active than triadimenol.

A convenient method for the synthesis of pyridoxine alkenyl derivatives by the Wittig reaction of [(2,8-dimethyl-4H-[1,3]dioxino[4,5-c]pyridin-5-yl)methyl]triphenylphosphonium chloride with aldehydes was suggested. Some of the compounds obtained exhibit antitumor activity in vitro.

New ruthenium and osmium carbonyl clusters with 1,3,5-triaza-7-phosphatricyclo-[3.3.1.13.7]decane and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane ligands were synthesized using Me₃NO as an initiator. The data on antiproliferative activity of new compounds against ovarian carcinoma cell cultures A2780 (cisplatin-sensitive) and A2780cisR (cisplatin-resistant) are reported. The dependence of cytotoxicity on the number of phosphine ligands was demonstrated.

The present investigation is based on the paradoxical dichotomy of the biological action of nitric oxide (NO). Depending on its concentration in the organism, it can have therapeutic or pathogenic effect. It was shown that during the treatment with cisplatin (cPt) or cyclophospamide (CP), adjunct therapy with ascorbic acid (AA) known to increase the NO content in the organism extended the average lifespan (ALS) by 20—30% as compared to cytostatic monotherapy. Combination of cytostatics with sodium nitrate extended ALS by 20—38% depending on the concentration of the nitrate. The efficiency of cytotoxic therapy in combination with two chemo sensitizers (NaNO₃ and hydroxamic acid) also depends on the concentration of injected NaNO₃. Addition of AA to these combinations extended ALS by 16%, or inhibited it by 40%. Variation of the dose of injected NaNO₃ that is a NO donor in combination with endogenous NO stimulated with AA controls the action of cytostatics and combinations thereof.

Selective carboxylesterase inhibitors are employed as modulators of hydrolytic metabolism of ester or amide-containing drugs. Using the Molecular Field Topology Analysis (MFTA), the models for the relationships between the structures and inhibitory activities of 5-halomethyl-2-aminothiazolines against acetylcholinesterase, butyrylcholinesterase, and carboxylesterase were built, the molecular design was performed, and a focused library of potentially active and selective carboxylesterase inhibitors was proposed.

A 3D QSAR study of a set of positive allosteric modulators of AMPA receptors was performed using the CoMFA approach. It was shown that the van der Waals component introduces the major contribution to the predicted pEC₅₀ values, while the contribution of the electrostatic component is minor. The pharmacophore hypothesis for positive allosteric modulators was generated and validated.

A reaction of sodium bis(trimethylsilyl)amide with 2-bromopyridine leads to N,N-bis(trimethylsilyl)- and N,3-bis(trimethylsilyl)-2-pyridinamine.