O. V. Fedorova

Aminoazoles in the three-component synthesis of 7-substituted 6-ethoxycarbonyl-5-methyl-4,7-dihydroazolo[1,5-a]pyrimidines

The three-component synthesis of 7-substituted 6-ethoxycarbonyl-5-methyl-4,7-dihydroazolo[1,5-a]pyrimidines was carried out for the first time by the reactions of aminoazoles (3-aminopyrazole, 3-amino-1,2,4-triazole, or 5-aminotetrazole) with acetoacetic ester and aliphatic, aromatic, or heteroaromatic aldehyde.

Synthesis and anti-tuberculous activity of diesters based on isosteviol and dicarboxylic acids

Diesters based on isosteviol and dicarboxylic acids were synthesized and tested for antituberculous activity. Isosteviol and some of its derivatives exhibit appreciable tuberculostatic properties in vitro, the activity being dependent on the length of the polymethylene spacer connecting two ent-beyeran fragments. The mechanism of the antituberculous action of isosteviol derivatives are discussed.

Multicomponent sonochemical synthesis of podands.

An efficient sonochemical methodology is described for the synthesis of new podands containing substituted dihydropyrimidines.

Spatiotemporal structure of a laser beam over 144 km in a Canary Islands experiment

We analyzed the observations of scintillations in a laser beam (532 nm, ~200 mW power) traveling along a 144 km path at an altitude of 2.2-2.4 km above sea level, just above the atmospheric boundary layer, between the islands of La Palma and Tenerife. The observations were performed during nighttime on 18 July 2011, by means of a telescope with an aperture diameter of 1 m. Strong scintillations were observed. The estimates of spatial spectra and correlation functions indicated that the observed intensity fields possess, statistically, a locally isotropic structure, which agrees with the idea of a locally isotropic turbulence. The estimates of spatial autospectra and autocorrelation functions of the intensity field indicated that the characteristic scale of the internal structure of the observed clusters is 6.5-8 mm, while the characteristic size of the clusters is 4-5 cm. The major contribution to the observed scintillations comes from the inhomogeneities of the intensity field with scales from 1-2 cm up to 10-12 cm. The analysis of the cross-spectra indicated that the hypothesis of frozen turbulence introduced by Taylor can be used for the description of spatiotemporal structure of intensity fluctuations of laser beams traveling through long paths in the atmosphere.

Sonochemical synthesis of Biginelli compounds

The ultrasound effect accelerates the Biginelli reaction 40 and more times. A sonochemical method for the synthesis of ethyl 4-R-6-methyl-2-oxo- and 4-R-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates was developed. The target products were obtained within 2 to 5 min in 90—95% yields.

Synthesis of alkyl 5-aryl-7-methyl-1,5-dihydrotetrazolo-[1,5- a ]pyrimidine-6-carboxylates

Alkyl 5-aryl-7-methyl-1,5-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylates were obtained by melting acetoacetic acid esters with 5-aminotetrazole and aromatic aldehyde.

Asymmetric Biginelli Reaction Catalyzed by Silicon, Titanium and Aluminum Oxides

The asymmetric Biginelli reaction was investigated in the presence of N-[(2S,4R)-4-hydroxyprolyl]-(S)-1-phenylethylamine as chiral inducer and silicon, titanium or aluminum oxides (individual and mixed, bulk and nanosized) as heterogeneous catalysts. It has been shown that all studied oxides improve chemo- and stereoselectivity of the Biginelli reaction.Graphical Abstract

Synthesis and turbeculostatic activity of podands with fluoroquinolone fragments

Fluorine-substituted quinolonecarboxylic acids are known as synthetic antibacterial drugs with a broad spectrum of activity, which are successfully used for the therapy of various bacterial diseases, including tuberculosis [1 ]. Nevertheless, problems pertaining to the appearance of bacterial strains resistant to quinolones stimulate researchers to continue investigations aimed at a modification of the known fluroquinolones [2]. We have attempted to modify a fluoroquinolone fragment responsible for penetration into bacterial ceils, with the pttrpose of increasing the transport function of the molecule, since it is known that fluoroquinolones (in particular, pefloxacin) penetrate into bacterial cells by a simple diffusion mechanism [3]. In order to find reaction pathways to fluoroquinolones possessing increased penetrating ability with respect to the cell membranes, we have synthesized compounds containing podand residues that are known [4] to readily pass through the cellular barriers. Because of the low nucleophilicity of glycols, the oxygen-containing podands IV were obtained under rigid conditions from the ethyl ester of 1-ethyl-6,7-difluoro-4-oxo-l,4dihydro-3-quinolinecarboxylic acid (Ib), in which the mobility of a fluorine atom in position 7 is somewhat higher than in the acid (Ia). Podands V and VI were obtained by direct interaction of acid Ia with polyethylene polyamines. Potassium carbonate was used as the acceptor of hydrogen chloride in the synthesis of compounds IV and VI, whereas triethylamine was used for the same purpose in the synthesis of compounds V known to form strong complexes with potassium cations. Podands-hydrazones VII were obtained by heating formylpodands III with 7-hydrazino-4-oxo-6-ftor-l-ethyl-l,4dihydro-3-quinolinecarboxylic acid (II) in DMF.

Synthesis andin vitro tuberculostatic activity of podands containing semicarbazide or thiosemicarbazide fragments

Previously we have reported on a significant tuberculostatic activity of podands containing thioureide fragments [I]. In continuation of that work, we have synthesized a series of new podands, containing semicarbazide or thiosemicarbazide fragments, and characterized their tuberculostatic activity in vitro. The new compounds (I Ia-IIc and IIIa-IIIc) were synthesized using the reactions of formylpodands (Ia-Ic) , differing in the length of the hydroxyethylene fragment, with semicarbazide or thiosemicarbazide in a D M F H 2 0 ~H3COOH medium:

Catalysts for enantioselective Biginelli reaction based on the composite silica-zirconia xerogels prepared using different zirconium sources

AbstractThe composite silica-zirconia xerogels have been prepared via sol–gel method using zirconium oxychloride, oxynitrate, acetate and sodium silicate as the precursors. The prepared materials have been characterized using FTIR, TG/DTA, EDX and surface area analyses. It has been established that surface area of silica-zirconia xerogels significantly depends on the zirconium source, but phase transitions and structural features of the xerogels seem to be unaffected by the choice of the zirconia precursor. Prepared xerogels increase the activity of chiral inductor in the asymmetric Biginelli reaction. The anion of the zirconium salt adsorbed on the surface of the synthesized material and the presence of Si–O–Zr heterolinkages determines the reaction yield. The highest chemo- and enantioselectivity towards formation of ee isomer have been provided by the catalyst prepared from zirconium oxychloride.