Reaction of chloropyrido[2,3-d]pyrimidines with DBSO

Communication 5 from the series Pyrido[2,3-d]pyrimidines. See [1] for communication 4.     

Synthesis of δ-hetaryl-α,α-dicarbonylalkadienes and a study of their isomerization

The reaction of β-hetarylacrolein and β-hetaryl-α-methylacroleins with esters of acetoacetic and malonic acids was studied. The structures of the products obtained were established using¹H and¹³C NMR and UV spectroscopy. (E) and (Z) isomers of α,α-dicarbonylalkadienes, their mixtures with the corresponding 2H-pyrans or exclusively 2H-pyrans are formed depending on the substitution in the starting aldehyde and the ester used. 6-Methyl- and 3,6-dimethyl-5-carbalkoxy-2-(2-pyridyl)pyrans are converted upon heating to substituted 2-(pyrilidene)pyrans. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 483–496, April, 1997.     

High-sensitivity modulation differential scanning calorimetry of protein denaturation

Method of high-sensitivity modulation differential scanning calorimetry was applied for investigation of the kinetically controlled irreversible thermal denaturation of the trypsin inhibitor from soybeans (Kunitz inhibitor, KI) in diluted solution. The measurements were carried out with a temperature-modulation capillary nanocalorimeter designed and produced by the Institute of Biological Instrumentation of the RAS (Pushchino, Russia). An algorithm of the experimental data processing and corresponding software were developed. It was shown that the modulation nanocalorimetry allows one to obtain in one experiment the temperature dependence of the rate constant for irreversible protein denaturation. The temperature dependence of the rate constant and the activation energy of the irreversible denaturation of Kunitz inhibitor were determined. The obtained value of the activation energy (E _a = 206 ± 6 kJ mol^?1) agrees with independent estimates of this kinetic parameter.     

Determination of the tautomeric structures of uracil thiosubstituted derivatives by IR and RRS spectroscopy

The force fields, vibration frequencies, and relative intensities of the RRS spectra of uracil thiosubstituted derivatives are calculated and analyzed. It is shown that 2S-, 4S-and 2S,4S-thiouracils as well as 2-mercapto-4-thio-and 2,4-dimercapto-tautumers of dithiouracil occur in a neutral water solution.     

Coexpression of Vimentin and Cytokeratins in Human Melanoma Cell Lines

Moscow University Chemistry Bulletin - Abstract—Molecular heterogeneity in seven human metastatic melanoma cells lines is revealed using a double immunofluorescent assay by flow cytometry. It...     

Calculations of chemical equilibria in heparin-arginine-H<Subscript>2</Subscript>O-NaCl and MCl<Subscript>2</Subscript>-heparin-arginine-H<Subscript>2</Subscript>O-NaCl systems (M = Ca<Superscript>2+</Superscript>, Mg<Superscript>2+</Superscript>) in a physiological solution

Chemical equilibria in the high-molecular-weight heparin (Na₄hep)-arginine (HArg)-H₂O-NaCl and MCl₂-Na₄hep-HArg-H₂O-NaCl systems of electrolytes (M = Ca²⁺, Mg²⁺) were calculated by the method of mathematical simulation of chemical equilibria from representative planned pH-metric titration experiment at 2.30 ≤ pH ≤ 10.50 in a physiological solution medium in the presence of 0.154 M NaCl as a background electrolyte at 37°C. The initial concentrations of the basic components were n × 10⁻³ M (n ≤ 4).     

Pyrido[2,3-d]pyrimidines 7. Reactions of 1,3-dimethyl-5,7-dichloro-6-nitropyrido-[2,3-d]pyrimidine-2,4-dione with amines. Synthesis of derivatives of triazolo(4′,5′:4,5)pyrido[2,3-d]pyrimidine

The reaction of 5,7-dichloro-6-nitropyrido[2,3-d]-pyrimidine-2,4-dione with amines gave products of the substitution of one or two chlorine atoms by ammo groups. The catalytic reduction of 6-nitro-5,7-disubstituted pyrido[2,3-d]pyrimidines with hydrogen over palladium oxide on carbon leads to 5,6-diamino- and 5,6,7-triaminopyridopyrimidines, the reaction of which with amyl nitrite in acetic acid gives triazolo(4,5:4,5) pyrido[2,3-d]pyrimidines.For communication 6 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 398–401, March, 1993.     

Calculation of two-photon absorption spectra of monosubstituted benzenes with accounting for the Herzberg-Teller effect

A calculation was carried out of relative line intensities of two-photon absorption spectra of fluoro- and chlorobenzene in the¹A₁¹B₁ transition region. The separate aspects of the calculation procedure used are discussed, which is based on the concept of the matrix element of a transitional dipole moment in the Herzberg—Teller approximation and was previously successfully applied to electron-absorption and resonance Raman spectra. A satisfactory correspondence between the calculation results and the experimental data has been found.Saratov State Pedagogical Institute. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 1, pp. 101–104, January–February, 1993.     

Constructing smooth interpolation splines

The authors present formulas for constructing continuous splines and smooth splines which are exact on any power of a given function.