The 1,3-dipolar cycloaddition of cyclic nitrone derived from tartaric acid with (S)-5-hydroxymethyl-2(5H)-furanone leads to a single adduct which was transformed into 1,2,6,7-tetrahydroxy-2-hydroxymethyl-indolizidine via reaction sequence involving protection of the hydroxymethyl group, reduction of the lactone moiety, protection of the resulting diol, and the N-O hydrogenolysis followed by the intramolecular alkylation of the nitrogen atom.
A convenient and general method for the preparation of new 7-substituted 3-methylisoxazolo[5,4-e][1,2,4]triazepin-4-ones from 5-amino-3-methylisoxazole-4-carboxylic acid methylhydrazide and carbonyl compounds is described. The synthesized compounds exhibited immunosuppressive properties in the murine humoral immune response in vivo and the proliferative response of mouse splenocytes to mitogens. The X-ray structure of a representative compound is reported.
The reactivity of a series of cycloalkanones of the general formula (CH2)(n)CO, where n = 4, 5, 6, 7, 11 and 14 in the transfer hydrogenation reaction over magnesium oxide as the catalyst, either in vapour or liquid phase (VP or LP) has been studied. In the VP mode of reaction the activity of MgO treated with triethylamine, water, phenol or benzoic acid in the reduction of cyclopentanone by propan-2-ol has been determined. A strongly diminished or residual activity of MgO has been observed after the catalyst's treatment with phenol or benzoic acid, respectively. The occurrence of side reactions of cyclopentanone in the LP mode of reaction resulted in high conversions of the ketone (up to 91%), very low yields of cyclopentanol (I) (below 6%) and very high yields of 2-cyclopentylidene-cyclopentanone (II) (> 80%).
The synthesis and characterization of new coordination compounds of some organotin(IV) chlorides with fexofenadine are reported; the ligand molecules appear to be bound to the tin atom through carbonyl oxygen atom. The structure of the synthesized compounds has been characterized by elemental analyses, and bonding in these complexes is discussed in terms of their IR, 1 H NMR and through Mossbauer studies. The spectroscopic results obtained are in full agreement with the proposed 1:1 stoichiometry. The synthesized complexes have been screened for anti-inflammatory effect. The results obtained showed that triphenyltin(IV) derivatives of fexofenadine exhibited promising anti-inflammatory effect as compared to the other tin(IV) derivatives ofthe same ligand.
The reaction of 1,2-di(1-adamantyl)-2-thioxoethanone (4c) with diazomethane and 2-diazopropane yielded 2-acylthiiranes 6a and 6b, respectively, and no 1,3-oxathioles of type 7 were formed. The reaction course is explained via [2+3]-cycloaddition, elimination of N2, and 1,3-dipolar electrocyclization of the intermediate acylsubstituted thiocarbonyl ylides of type 1. The failure of the competitive 1,5-dipolar electrocyclization is a result of the sterically unfavorable conformation of 1a.
To understand various substitution, oxidation or degradation reactions for uracil, quantum-chemical calculations were performed for two classes of charged radicals (cations and anions) of uracil (U +• and U -• ) and model compounds: phenol (P +• and P -• ) and hydroxyazines (HP1-4 +• and HP1-4 -• ). In calculations, all possible eighteen prototropic tautomers-rotamers of U and all possible five prototropic tautomers-rotamers of P and HP1-4 were considered. Stabilities, internal effects and aromatic character, estimated for charged radicals, were compared with those observed previously for neutral molecules. The greatest changes of the tautomeric preferences take place for radical anions. One-electron reduction stabilizes the keto and amide functions in studied compounds, whereas one-electron oxidation favors the enol function for phenol and the amide function for uracil and hydroxyazines.
The synthesis of N-terminal guanidme derivatives of three dipeptides Ala-Ala, Ala-Leu, Ala-Phe and three dipeptides containing betaine as an N-terminal amino acid: Bet-Ala, Bet-Leu, Bet-Ile has been carried out. The transport studies of the obtained pscudo-peptides and corresponding natural peptides into E. coli K 12 mutant strains have also been performed. The results indicate that modified dipeptides containing N-terminal guanidine or betaine arc not transported into E. coli K12 cells
Base hydrolysis of some (aminomonocarboxylato)(tetraethylenepentamine)cobalt(III) complexes were studied in aqueous medium. The pseudo-first order rate constant fitted the relationship. k(obs) = k(OH)[OH-](T) at 0.005 <= [OH-] mol dm(-3) <= 0.10 at 293.15 K-313.15 K, (I = 01 mol dm(-3)), where k(OH) denotes the second order base hydrolysis rate constant. The alpha beta R isomer of the alpha-alaninato complex reacted approximately 8 times faster than its alpha beta S analogue at 298.15 K. Also the reactivity difference k(OH)(pyridine-2-carboxylato)/k(OH)(beta-alaninato) approximate to 3 for the (alpha beta S) isomer is indicative of the relative electron displacement property of the pyridine ring and the aliphatic chain attached to the bound carboxylate function which influences partly the Co-O bond strength. The D-cb mechanism is valid for all these substrates. The ionic strength dependence of k(OH) in the range 0.01 <= I, mol dm(-3) <= 0.1 for glycinato and beta-alaninato complex also confirmed the relationship log k(OH) = log k(OH)(0) + S-1[I-1/2/(1+1(1/2))+CI] where C is an adjustible parameter S-1 = 2bZ(A)Z(B), with b = 0.509 at 298.15 K, Z(A) and Z(B) denote charges of the reactant species. The acid catalyzed aquation indicated that alpha beta R-[(tetren)CoO2C-(CH3)NH3](3+) aquates via spontaneous (k(o)) and acid catalyzed (k(aq)) path. However, these reactions are extremely slow (k(o) = (1.74 +/- 0.17)x10(-5) s(-1), k(aq) = (2.72 + 0.05)x10(-5) dm(3) Mol(-1) s(-1) at 333.15 K and I = 1.0 mol dm(-3)).
Metal complexes of Ti(III), VO(IV), Cr(III), Mn(III), Fe(III) and Zr(IV) with Schiff base derived from 2-hydroxy-5-methylacetophenone and benzoyl hydrazide have been synthesized and characterized on the basis of elemental analysis, infrared spectra, magnetic moment, electronic spectra and thermogravimetric studies. Various kinetic parameters evaluated from thermal decomposition data and thermal stabilities of the complexes are also reported. The antibacterial and antifungal activities of 2-hydroxy-5-methylacetophenone benzoylhydrazone (HMABH) and its complexes have been investigated against various bacterial strains using the disc diffusion technique. All complexes exhibit good biological activity as compared to free ligand. Solid-state electrical conductivity of ligand and its complexes have also been studied over a wide range of temperature and it was found that compounds exhibit semiconducting behavior in the studied range.
The multi-channel reactions of proton transfer of water-bridged serinamide have been investigated employing the B3LYP/6-311++G** level of the theory. The reactants, transition states and products of four channels have been optimized. Furthermore, the validity of these transition states has been validated by the internal reaction coordinate (IRC). The activation energies, standard enthalpy and free energy change have also been calculated. From the free energy changes we conclude that the water molecule serving as a bridge facilitates the proton transfer reaction.
Gas stationary conformers of lactic acid and its derivatives (F, Cl, Br and CN replace OH) have been optimized at the B3LYP/6-311++G(2d,2p) level of density functional theory (DFT). We have found that the molar rotation and the parameters (the helical pitch s and helical radius r) have the direct proportions, in agreement with the formula [M](D) = K{(r(2)s)/(4 pi(2)r(2)+s(2))}. This provides theoretical predictions for profound study on the helical structure in the future.
Grain boundary diffusion of copper (GBD) in aluminum was investigated by EPMA in the temperature range from 300 to 400 degrees C. The triple product s delta D(gb) (s-segregation coefficient, delta - grain boundary width, D(gb) - GBD coefficient) was calculated using Fisher-Gibbs solution methods - by measuring of GB copper concentration as a functional penetration depth and the contour angle (at the top of diffusion wedge).In the first case s delta D(gb) = 5.1.10(-11) m(3)/s.exp(-102 kJ/mol/RT)and in the second case s delta D(gb) = 1.4.10(-11) m(3)/s.exp(-94 kJ/mol/RT)
Two series of novel 1-[3-(4-aryl-1-piperazinyl)]- and 1-[2-hydroxy-3-(4-aryl-1-piperazinyl)]propyl derivatives of amides of 7-methyl-3-phenyl-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidine-5-carboxylic acid (32-46) were synthesized. In the writhing syndrome test all the amides studied displayed analgesic action. The most potent effect was produced by compounds 32, 34, and 46. In the hot plate test only two amides, 34 and 37, showed strong analgesic activity. Furthermore, most of the investigated substances significantly suppressed spontaneous locomotor activity in mice and prolonged barbiturate sleep of these animals. QSAR analysis of the 14 new and 14 earlier described compounds was made.
Enantiomerically pure (R)-1-(1-phenylethyl)imidazoles 4a,b can be prepared conveniently from α-(hydroxyimino)ketones 1, (R)-1-phenylethylamine and formaldehyde, followed by deoxygenation with Raney-Ni. Similarly, the reaction with (R,R)-trans-cyclohexane-1,2-diamine yields enantiomerically pure (R,R)-trans-1,1'-cyclohexane-1,2-diyl)imidazoles 4c,d. Alkylation of these imidazole derivatives with alkylbromides leads to the corresponding 3-alkylimidazolium bromides 6 and 8, respectively, which on treatment with sodium tetrafluoroborate are transformed into the corresponding tetrafluoroborates 7 and 9. Whereas some of the imidazolium salts 7 show properties of chiral ionic liquids, the bis-imidazolium tetrafluoroborates 9 are high-melting crystalline materials.
Protonation of (E)-1-ferrocenyl-2-(pyridin-4-yl)-ethylene with (+)-camphor-10-sulfonic and picric acid afforded salts displaying high second harmonic generation (SHG) efficiencies (70 and 10 x urea, respectively). Powder X-ray diffraction study confirmed crystallization of these salts in a noncentrosymmetric space group (P2). The electronic structure of the cationic part of the salts was studied by the DFT method.
Low temperature electronic spectra of potassium chromate: pure K 2 CrO 4 single crystal and the 1:20 solid solution of K 2 CrO 4 in K 2 SO 4 have been analyzed in detail using filtration and deconvolution methods. The 14000-19000 cm -1 spectral region of crystal has been found to contain extremely low intensity bands which have been assigned to spin and symmetry forbidden Cr←O charge transfer (CT) transitions. Surprisingly, the whole solid solution spectrum in the 19000-50000 cm -1 energy range was found to be composed exclusively from vibronic transitions with the coupled ν 1 Cr-O mode.
it is shown how infrared pump-probe spectroscopy can be used to measure sub picosecond variations of the oxygen-oxygen distribution function in liquid water, A diluted solution HDO/D2O rather than pure H2O is considered to switch off resonant vibrational interactions between water molecules; the local structure remains unchanged in this substitution. The present study is limited to times superior to 100-200 fs. This permits to avoid problems generated by hard sphere type collisions between water molecules, as well as the interference between ultrafast pump and probe pulses. It is then shown that the Novak-Mikenda type relations between the OH stretching frequency and the OO distance largely survive when going from standard to ultrafast infrared spectroscopy. Moreover, the infrared pump-probe profiles of OH stretching bands closely parallel the oxygen-oxygen distribution functions in this time domain. Infrared pump-probe spectroscopy is thus a useful substitute of time-resolved X-ray diffraction in this exceptional case.
This paper summarizes the results of the investigations on selected topics from the field of materials science, such as: composition and stability of the passive films on metal alloys and the effect of electrochemical and chemical modifications on the catalytic activity and selectivity of Cu-based amorphous alloys as well as of Raney Ni catalysts doped with Cr. Microscopic and surface analytical techniques like scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) provide an insight into the mechanism of the functionalization of the materials studied. The local chemical and morphological inhomogeneities at a micro- and nano-scale have been monitored. An attempt has been made to find an interrelation between the composition, structure and morphology of materials and their specific behavior in the processes considered.
