Diene synthesis with 2-pyrones and 2-pyridones. 31. Stereochemistry of the successive addition of two different dienophiles to 2-pyrones

The stereochemistry of the successive addition of two different dienophiles, viz., N-phenylmaleinimide and 4-phenyl-1,2,4-triazoline-3,5-dione, to 2-pyrones was studied. The configurations of the mixed adducts (bisimides) obtained were established by PMR and mass spectrometry. It is shown that in all cases the reactions proceed with the formation of mixtures of syn and anti isomers, the ratios of which depend on the positions of the methyl groups in the starting 2-pyrones.See [1] for communication 30.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1476, November, 1982.     

Energy spectrum of primary cosmic rays at energies of 2 × 10<Superscript>13</Superscript> to 5 × 10<Superscript>17</Superscript> eV,according to Tien Shan data

The primary cosmic ray energy spectrum at energies of 10¹⁵ to 5 × 10¹⁷ eV is presented using the results from observations by the Tien Shan HADRON array. The spectrum was obtained from the spectrum of showers according to the number of electrons using a new way of determining the parameter of spatial distribution function S of electrons. The energy spectrum can be extended to low energies up to 2 × 10¹³ eV using data from separate experiments at the former Tien Shan array. Conclusions are drawn regarding changes in the form of the spectrum and its chemical composition at energies over 10¹⁶ eV. The spectrum is compared to the results from the TUNKA installation.     

(Ga,Ge)-Analogue of Tourmaline: Crystal Structure and Composition

Crystallography Reports - Crystals of a (Ga,Ge)-analogue of tourmaline have been synthesized by hydrothermal method in the temperature range of 600–650°C under a pressure of 100 MPa. The...     

Enzymatic polymerization of vinyl monomers

The possibility of using horse radish peroxidase as a catalyst for polymerization of monomers (vinylformamide and sodium vinylsulfonate) in the presence of hydrogen peroxide and 2,4-pentanedione in aqueous medium at room temperature was studied.     

Silyl Modification of Biologically Active Compounds. 8. Trimethylsilyl Ethers of Hydroxyl-containing Thiazole Derivatives

Trimethylsilyl ethers of various hydroxyl-containing thiazole derivatives have been synthesized. The psychotropic activity (in vivo) and the cytotoxicity (in vitro on tumor cell lines HT-1080 and MG-22A) of these ethers and of their unsilylated precursors have been studied. It was discovered that the obtained compounds possess a sedative action. A moderate cytotoxic effect was detected for piperidine-containing thiazoles, displayed most strongly in relation to MG-22A cells.     

Study of the acylation reaction of 2,6-dimethyl-3,5-pyridinedicarboxylic acid hydrazides

Acylation of 3-ethoxycarbonyl-2,6-dimethyl-5-pyridinecarboxylic acid hydrazide and 2,6-dimethyl-3,5-pyridinedicarboxylic acid dihydrazide using aromatic acid chlorides gave the corresponding N-aroyl hydrazides. It was found that the hydrazinolysis of 3-ethoxycarbonyl-2,6-dimethyl-5-pyridinedicarboxylic acid N-aroyl hydrazides occurred not at the ester group but as a rehydrazinolysis reaction at the dihydrazide fragment. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1834–1845, December, 2005.     

Synthesis of Arylidene Derivatives of 1-Aryl-3H-pyrrol-2-ones

The aminolysis of 5-aryl-3-arylidene-3H-furan-2-ones by the action of aromatic amines leads to the formation of substituted amides of 4-oxo acids, the subsequent azacyclization of which in the presence of acetic anhydride leads to the formation of 1,5-diaryl-substituted 3-arylidene-3H-pyrrol-2-ones. The mechanism of the occurring and alternative transformations is discussed.     

Heat capacity and thermodynamic functions of 2-methylbiphenyl and 3,3′-dimethylbiphenyl in the range of 6 to 372 K

The heat capacities of 2-methylbiphenyl and 3,3′-dimethylbiphenyl are measured by means of low-temperature adiabatic calorimetry in the temperature range of 6 to 372 K. The thermodynamic characteristics of fusion and the glass transition of the investigated compounds are determined. The saturation vapor pressure and enthalpy of vaporization of 3,3′-dimethylbiphenyl are determined according to the dynamic method based on the transfer of a substance vapor in a helium flow. The absolute entropies and changes in Gibbs energies of biphenyl derivatives are calculated from the data obtained in the condensed and ideal gas states. The contribution of the C_b-(C_b) group is determined using the Benson additive method for calculating the absolute entropies of biphenyl derivatives in the liquid state (where C_b is the carbon atom in a benzene ring).     

Synthesis of 3-R-2-aryl-4,6-dinitroindoles and specific features of their reactions with anionic nucleophiles

Reaction of different anionic S-nucleophiles with 3-R-2-aryl-4,6-dinitroindoles led to a regiospecific nucleophilic substitution of the nitro group in position 4 with 6-NO₂ group remaining intact. The representatives of some peri-annulated polycyclic systems were synthesized on the basis of the substitution products. Dedicated to Academician V. A. Tartakovsky in honor of his 75th anniversary. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1543–1547, August, 2007.     

Twofold reactivity of 1,2-disubstituted dihydro-n-heteroaromatic systems. 10. Synthesis and aromatization of ferrocene-containing hantzsch esters

1-Ferrocenylphenyl-4-aryl(furyl)-2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridines and 4-ferrocenyl-2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridines (Hantzsch esters) have been prepared, and their reactions with triphenylcarbenium and 1-oxo-2,2,6,6-tetramethyl-piperidinium perchlorate salts have been studied. Treatment with triphenylmethyl perchlorate results in oxidation of the ferrocenyl substituent to the ferrocenium cation, whereas treatment with the oxoammonium cation results in aromatization and the formation of salts containing a pyridinium cation and a neutral ferrocene ring. A 4-ferrocenyl-containing Hantzsch ester which was unsubstituted at the nitrogen atom constituted a single exception to this trend; it could be aromatized only upon treatment with sulfur.For Communication 9, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1094–1101, August, 1986.