Aidar T. Gubaidullin

The synthesis of tetracarbonyl derivatives of thiacalix(4)arene in different conformations and their complexation properties towards alkali metal ions

Abstract The three conformations of 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrakis[(benzoyl)methoxy]-2,8,14,20-tetrathiacalix[4]arene 1 : cone, partial cone and 1,3-alternate, were prepared by the treatment of 5,11,17,23-tetra-tert-butyl-2,8,14,20-tetrathiacalix[4]arene-25,26,27,28-tetraol (TCA) with α-bromo acetophenone in the presence of appropriate alkali carbonate M2CO3 (M=Na, K, Cs) as base catalyst in acetonitrile. Structure of the conformers were established by 1H NMR, 1H–1H COSY, 1D NOE, 2D ROESY and X-ray experiments. The alkali cation binding selectivity of the obtained macrocycles was investigated by the ion-pair extraction method.

Three different types of chirality-driven crystallization within the series of uniformly substituted phenyl glycerol ethers.

Seven chiral arylglycerol ethers 2-R-C(6)H(4)-O-CH(2)CH(OH)CH(2)OH (R = H, Me, Et, Allyl, n-Pr, i-Pr, tert-Bu) were synthesized in racemic and scalemic form. The IR spectra, melting points, and enthalpies of fusion for racemic and scalemic samples of every species were measured, the entropies of enantiomers mixing in the liquid state and Gibbs free energies of a racemic compound formation were derived and binary phase diagrams were reconstructed for the whole family. Solid racemic compounds stabilities were ranked for the four substances. Spontaneous resolution was established for the registered chiral drug mephenesin and its ethyl analogue. Metastable anomalous conglomerate, forming crystals having three independent R* and one independent S* molecules in the unit cell, is formed during solution crystallization of tert-butyl derivative; metastable phase transforms slowly into traditional racemic conglomerate.

Synthesis, structure and biological activity of nitroxide malonate methanofullerenes

Two nitroxide methanofullerenes was synthesized for the first time, and their structures and biological activities studied. It was shown by X-ray single crystal analysis that the methanofullerene with two nitroxide groups forms a 1 : 2 inclusion complex with chloroform and has a nearly tetrahedral (diamond-like) arrangement of fullerene-fullerene interactions in the crystal. For the first time, it has been found that malonate nitroxide methanofullerene in combination with the known anticancer drug cyclophosphamide (CPA) shows high antitumor activity against leukemia P-388.

Chiral drug timolol maleate as a continuous solid solution: Thermochemical and single crystal X-ray evidence

Thermochemical properties of binary mixtures of the popular chiral drug timolol maleate (TM) were investigated by differential scanning calorimetry. It was found that there are no eutectic points on the melting phase diagram, and the enantiomeric components form a continual set of solid solutions over a wide concentration range. The crystal structure of heterochiral racemic TM is essentially isostructural with that of the homochiral (S)-TM, having close cell parameters but containing a crystallographic inversion centre. The crystal structure of the homochiral TM contains two symmetry independent molecules in the unit cell. These molecules have different conformations but are approximate mirror images of each other in the crystal lattice. Within the homochiral crystals only one site of two changes its nature in the heterochiral crystals. The solid solution of TM could be treated as the solid solution of a regular racemic compound and a pure enantiomer.

Deoxygenation of Some α-Dicarbonyl Compounds by Tris(diethylamino)phosphine in the Presence of Fullerene C60

The reactions of such cyclic α-diketones as acenaphthenequinone, aceanthrenequinone, and N-alkylisatins, with hexaethyltriaminophosphine in the presence of the fullerene C(60), lead to the formation of methanofullerene derivatives under mild conditions. This process proceeds via deoxygenation of the dicarbonyl compound by the P(III) derivative and is likely to involve the intermediate formation of α-ketocarbenes. The structure of some methanofullerenes has been confirmed by NMR and XRD. The electrochemical behavior of the methanofullerenes was also investigated.

The structure of 1-phenyl-3-benzoylamino-4-benzoylpyrazol-2-in-5-one

Abstract Crystal and molecular structure of 1-phenyl-3-benzoylamino-4-benzoylpyrazol-2-in-5-one as a product of the benzoylation of 1-phenyl-3-benzoylaminopyrazol-2-in-5-one was characterised by X-ray single crystal diffraction. It is shown that 1-phenyl-3-benzoylamino-4-benzoylpyrazol-2-in-5-one exists in the solid phase in an NH-tautomeric form, which is stabilised by two intramolecular hydrogen bonds and one intermolecular bond with the solvate dioxane molecule, the latter being used as a solvent for recrystallisation.

Metastable tert-butylcalix[6]arene with unusually large tunable free volume for non-threshold enclathration of volatiles

A metastable material with tunable free volume of molecular size, vapor sorption properties of a porous sorbent and variable thermal stability was prepared from tert-butylcalix[6]arene.

Ring contraction in reactions of 3-benzoylquinoxalin-2-ones with 1,2-phenylenediamines. Quinoxaline-benzoimidazole rearrangement

The reactions of 3-benzoylquinoxalin-2-one and its N(1)-alkyl derivatives with 1,2-phenylenediamines were accompanied by ring contraction as a result of the quinoxaline-benzoimidazole rearrangement giving rise to 2-benzoimidazolyl-substituted quinoxalines. The possible pathways of these reaction are discussed.

A facile synthetic route to convert Tb(III) complexes of novel tetra-1,3-diketone calix[4]resorcinarene into hydrophilic luminescent colloids

The work presents the synthesis of a novel calix[4]resorcinarene cavitand bearing four 1,3-diketone groups at the upper rim and its complex formation with Tb(III) ions in DMF and DMSO solutions. Electrospray ionization mass spectra, 1H NMR, UV-Vis and luminescence spectra indicate a long (three hours at least) equilibration time for the complex formation between the cavitand and Tb(III) in alkaline DMF and DMSO solutions. These results are explained by the restricted keto–enol conversion, resulting from the steric hindrance effect of the methylenedioxy-groups linking the benzene rings within the cavitand framework. A facile synthetic route to convert luminescent Tb(III) complexes of various stoichiometries into luminescent hydrophilic colloids is disclosed in this work. The route is based on the reprecipitation of the Tb(III) complexes from DMF to aqueous solutions with further polyelectrolyte deposition without prior separation of the luminescent complexes. The luminescent colloids exhibit high stability over time and in buffer systems, which is a prerequisite for their applicability in analysis and biolabeling.

The Kornblum Reaction of α-Substituted 3-Benzyl-1,2-dihydro-2-oxoquinoxalines. Synthesis and Structure of 3-Benzoyl-2-oxo-1,2-dihydroquinoxaline

A method has been developed for the preparation of 3-benzoyl-2-oxo-1,2-dihydroquinoxaline by the reaction of 3-(α-chlorobenzyl)-1,2-dihydroquinoxaline under Kornblum reaction conditions to the corresponding α-azido derivative and then acid fission of the latter. The structure of the target ketone has been confirmed by X-ray analysis.