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Replacement of terminal atoms of Br in 1,3-bis(bromopentyl)-5(6)-substituted uracils with 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole, 2-mercaptoimidazole, and 2-mercaptobenzimidazoles resulted in a series of acyclic compounds and isomeric heterocyclophanes. Structures of macrocyclic regioisomers were unambiguously determined by NMR data. One of the regioisomers exhibits a hypochromic effect with respect to model compounds. The acyclic uracils obtained bridged with five-membered heterocycles are alkylated with methyliodide and methyl tosylate, and oxidated with m-CPBA, H2O2, and I2.

A series of acyclic compounds with two 3,6-dimethyluracil or 3-methyluracil units attached to a a thymine or isocyanurate fragment by polymethylene or xylylene spacers are investigated. Ring-closure reactions with paraformaldehyde in aqueous HCl in the presence of copper(I) chloride afforded pyrimidinophanes which can be considered macrocyclic counterparts of the acyclic triuracils. By X-ray diffraction data the structures of the macrocycles in the solid state are characterised by a close arrangement of the uracil units, but there are no π-π contacts between them. On the contrary, significant hypochromism of the macrocyclic triuracils compared with their acyclic counterparts indicates stacking between the thymine and 3,6-dimethyluracil units in chloroform and H2O solutions. The conformational behaviour of the acyclic and macrocyclic compounds in solution has been determined by NMR, UV and computational methods. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Aggregation of amphiphilic calix[4]resorcinarenes (CRA) modified by carboxymethyl (1), 2-hydroxyethyl (2), methylamino acetal (3), and aminomethyl (4) fragments and their interaction with some synthetic (5, 6) and natural (7, 8) surfactants in the low-polarity solvent (chloroform) were studied by permittivity measurements and FT-IR spectroscopy. Compounds 1–4 and surfactants form aggregates at critical micelle concentrations (CMC) of 2.0·10−5–7.5·10−5 and 1.7·10−5–2.0·10−3 mol L−1, respectively. The CMC values of CRA—surfactant mixed aggregates depend on the surfactant structure and the structure and concentration of CRA. Analysis of the IR spectra of solutions of a series of amphiphilic CRA (2–4, 9, 10) and their mixtures with the cationic surfactant N-cetyl-N,N-dimethyl-N-(2-hydroxyethyl)ammonium bromide (5) showed that an increase in the concentration of the solutions in individual and mixed systems is accompanied by a decrease in the molar integral intensities and intensities in the maxima of the absorption bands of the O—H and C—H bonds down to the CMC point, after which these values change slightly. The discovered effect, which is differently pronounced for all systems studied, indicates that both the polar “head” groups and nonpolar fragments of CRA and surfactant are involved in the formation of supramolecules of the reverse micelle type in all cases.

A method for the synthesis of new calix[4]resorcinols tetra-3,5-di-tert-butyl-4-hydroxybenzyl derivatives is developed. Their interaction with methyldichlorophosphonate, dimethyldichlorosilane in the presence of a base leads to formation of organophosphorus-organosilicon cavitands. Acetylation of hydroxybenzylated calix[4]resorcinols with acetic anhydride leads to products of either incomplete or full acetylation depending on experimental conditions.

A new type of macrocycle containing 2-thio-4-aminopyrimidine and 6-methyluracil moieties has been studied by IR and UV spectroscopy. The vibrational spectra, conformations and amine–imine tautomerism of the aminopyrimidine fragments have been analysed within the framework of ab initio MO theory (HF/6-31G**, MP2/6-31G**) and density functional theory (B3LYP/6-31G**). According to experimental and theoretical results, the amino form is preferred in these compounds. Both intra- and intermolecular hydrogen bonds of the type NH⋯N are present in crystals, whereas in solutions, conformational equilibria with free NH groups are also obtained.

The IR and Raman spectra and conformations of the ionic liquid 1-ethyl-3-methyl-1H-imidazolium tetrafluoroborate, [EMIM][BF4] (6), were analyzed within the framework of scaled quantum mechanics (SQM). It was shown that SQM successfully reproduced the spectra of the ionic liquid. The computations revealed that normal modes of the EMIM+ (.) BF4- ion pair closely resemble those of the isolated ions EMIM+ and BF4-, except for the antisymmetric BF stretching vibrations of the anion, and the out-of-plane and stretching vibrations of the H-C(2) moiety of the cation. The most plausible explanation for the pronounced changes of the latter vibrations upon ion-pair formation is the H-bonding between H-C(2) and BF4-. However, these weak H-bonds are of minor importance compared with the Coulomb interactions between the ions that keep them closely associated even in dilute CD2Cl2 Solutions. According to the 'gas-phase' computations, in these associates, the BF4- anion is positioned over the imidazolium ring of the EMIM+ cation and has short contacts not only with the H-C(2) of the latter, but also with a proton of the Me-N(3) group.

The conformations and vibrational spectra of 2-benzylphenol have been analysed within the framework of scaled quantum mechanics. It is shown that the solid-state conformation of the 2-benzylphenol molecule corresponds to one of four potential energy minima predicted by non-empirical quantum chemical calculations for the isolated molecule. In the molten state and in diluted CCl4 solutions of the title compound this conformer coexists with another two spectroscopically detected conformations. The presence of several conformers gives rise to the observation of the corresponding number of vsCH2 and vasCH2 bands in the IR spectra, thus providing experimental evidence of the conformational sensitivity of the vCH2 frequencies. It is shown that vCH2 wavenumbers of different kinds of molecules, containing diphenylmethane fragments, are determined by the dihedral angles between the planes of the aromatic rings and the plane of the connecting methylene bridges, except for the case of short intramolecular contacts with the participation of the methylene protons.

3-Benzoyl-1,2-dihydroquinoxalin-2-one reacts with hydrazine and thiosemicarbazide to give the corresponding hydrazone and thiosemicarbazone. The reaction with arylhydrazines yields 3-(α-arylazobenzylidene)-1,2,3,4-tetrahydroquinoxalin-2-ones which are tautomeric to the respective arylhydrazones. On heating in boiling acetic acid, the products of both types undergo intramolecular cyclocondensation with formation of 3-phenylpyrazolo[3,4-b]quinoxalines (3-phenylflavazoles). 3-Benzoyl-1,2-dihydroquinoxalin-2-one thiosemicarbazone gives rise to flavazole structure only in the presence of methyl 3-chloro-2-oxo-3-phenylpropionate as a trap of thiocarbamoyl moiety. The cyclization of 3-(α-hydrazonobenzyl)-1,2-dihydroquinoxalin-2-one is accompanied by formation of quinoxalyl ketone azine.

Acyclic and cyclic counterparts containing thymine and two 3,6-dimethyluracil fragments bridged by methylene chains have been prepared and studied by UV and NMR spectroscopy; in water the uracil units of the acyclic counterpart form an intramolecular stack but arrange in a linear array in chloroform while the fragments of the uracilophane form an intramolecular stack both in chloroform and water; uracil units of bis(3,6-dimethyluracil-1-yl)butane and the macrocyclic counterpart form a stack in chloroform.

IR and Raman spectroscopy, normal coordinate analysis, and molecular mechanics were used to study the conformations of Cl(CH 2 ) 2 O–PCl 2 molecules. It is shown that gauche conformations of the Cl–CH 2 –CH 2 –O residue are energetically preferred in liquid. These are the only conformations remaining in the low temperature crystals, anti conformations being “frozen out”. In these crystals the POCC residue most probably adopts an extended conformation, the OC bond being in anti-position relative to the phosphorus lone pair. In the liquid state the extended conformers coexist with the convoluted conformations. Contrary to what might be expected from molecular mechanics considerations the latter conformers are practically as energetically stable as the former. The gap between experimental measurements and the respective molecular mechanics’ estimation is attributed to certain attractive intramolecular 1–5 interactions between the phosphorus and the chlorine atoms. It is used for rough quantitative evaluation of the energy of these interactions, which amount to ∽10–15 kJ mol −1 .

2,4,6-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)resorcinol in the crystal and in solution has a similar steric structure, favorable for its performance as peroxyl radical scavenger.

Esters and amides of 2,2-dichloro-3-(2-furyl)-3-hydroxypropionic acid were prepared by the reaction of furfural with dichloroacetic acid derivatives under the conditions of the Darzens condensation. The structures of the reaction products were confirmed by their1H NMR and IR spectra and chemical transformations.

The methyl ester and N,N-diethylamide of 2-azido-5-phenyl-4-thiazolecarboxylic acid were obtained by the reaction of the corresponding 4-substituted 2-hydrazino-5-phenylthiazole with NaNO2 in acid media. IR and UV spectroscopy were used to show that the compounds synthesized retain azide form in both the crystalline state and in solution. The reaction of azides with dicarbonyl compounds gave derivatives of 2-[5′-methyl-4′-acetyl-or 2-[5′-methyl-4′-ethoxycarbonyl-1′,2′,3′-triazol-1′-yl]-5-phenylthiazole-4-carboxylic acid.

The IR and Raman spectra and conformations of calix[4]arene, thiacalix[4]arene and their p-tert-butyl derivatives have been analysed within the framework of scaled quantum mechanics (SQM). It is shown that the introduction of four p-tert-Bu groups into the calixarene molecules influences the relative energies of their conformers and the enthalpy of the cooperative intramolecular H-bonding (DeltaH(intra)) almost negligibly. DeltaH(intra), evaluated from Iogansen's rule, amounts to approximately 26-28 kcal mol(-1) for the calixarenes and approximately 20-21 kcal mol(-1) for the thiacalixarenes, which essentially exceeds the enthalpies of non-cooperative H-bonds formed by related phenols. As a result of this strong bonding, bands of stretching, bending and torsion vibrations of an eight-membered cyclic system (OH...)4 arise, e.g., two delta(OH)4 bands are observed in the IR spectra of the most highly symmetric C4 cone conformations of calix[4]arene and thiacalix[4]arene. The "duplication" of the number of OH infrared bands is a good new indicator of cooperativity of intramolecular H-bonding of the calixarenes.

The compounds exhibiting hypervalent interactions of nonbonded atoms may be used as models of prereaction and transition states of nucleophilic substitution reactions. Our studies of the molecules X(CH2)2-O-PCl2 (X ˭ H (1); SCN (2); C2H5 (3); CH3O (4); Cl (5) revealed the possibility of subtle intramolecular 1–5 attractions between the sulfur (2) [I] or the oxygen (4) or the chlorine (5) and the phosphorus atoms. The attractions influenced perceptibly only the energy of the conformers with intramolecular contacts between the heteroatoms. A substantial energetical preference of the convoluted conformers (B) in the liquid state was observed in the case of 2. 4 and 5. In contrast. the molecules 1 and 3 preferred to exist in liquid in extended conformations (A). These dramatic changes cannot be explained by steric reasons or Coulomb attractions, and thus were attributed to hypervalent attractions between the heteroatoms. The relative energies of (A) and (B) conformers were used in quantitative assess...

1. Some dialkyl phosphoramidates were prepared and characterized. 2. Chloral adducts of dialkyl alkylphosphoramidates were prepared and characterized. 3. Under the action of triethylamine dialkyl alkyl(2,2,2-trichloro-1-hydroxyethyl)phosphoramidates break down with formation of dialkyl alkylformylphosphoramidates.

1. By the reactions of o- and p-(diphenylphosphinyl)phenols and o-(diphenylphosphinothioyl)phenol with acryloyl, methacryloyl, and 2-fluoroacryloyl chlorides the corresponding (diphenylphosphinyl)- and (diphenylphosphinothioyl)phenyl acrylates, methacrylates, and 2-fluoroacrylates were obtained. 2. The IR spectra of the compounds obtained were studied.

1. Reactions of chloral hemiacetals with dialkyl phosphorochloridites were studied. They lead in high yields to phosphorylated chloral hemiacetals containing tervalent phosphorus. 2. By the addition of sulfur and by oxidation the corresponding phosphorothioates and phosphates were obtained. 3. The reactions of 1-alkoxy-2,2,2-trichloroethyl dialkyl phosphites with benzyl chloride and with acetyl chloride and chloral take different courses. Possible mechanisms for these reactions are proposed.