Pyrimidines

The preparation of 4 (6)-substituted 2-fluoropyrimidines by the action of cesium fluoride on the corresponding 2-chloropyrimidines in aprotic dipolar solvents is described. Spectral data confirming the structures of the fluoropyrimidines obtained are presented.See [1] for communication XXX.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1281–1284, September, 1972.     

Synthesis of 2,5′-substituted 2′,5-bipyrimidines

Reaction of 5-substituted-2-methylpyrimidines with the Vilsmeyer complex followed by condensation of the resulting immonium salts and acroleins with aromatic amidines has given liquid crystalline 2,5-bipyrimidines.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 804–807, June, 1990.     

Thermoylysis of 1-phenyl-5-alkylsulfonyltetrazole in the presence of arylhydrazines. An instance of migration of an alkylsulfonyl group in a 1,3-dipole

When 1-phenyl-5-alkylsulfonyltetrazoles are heated with arylhydrazines, the heteroring is cleaved to give nitrogen and 1-arylamino-2-phenyl-3-alkylsulfonylguanidine. According to the proposed scheme, the intermediate product of nucleophilic addition of the arylhydrazine to the tetrazole decomposes to give nitrogen and a 1,3-dipole, which is stabilized by migration of an alkylsulfonyl group.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 549–552, April, 1977.     

Influence of electronegative substituents on the electronic spectra of the porphyrins in the form of dications

The positions of the electronic absorption bands and also the intensities of the Soret bands of the porphyrins with ethoxycarbonyl substituents in the form of dications have been calculated by the LCAO MO method in Huckel's approximation. Comparison with the experimental results shows good agreement.     

New solutions of the Einstein equations taking into account the vacuum effects of quantized fields

The Einstein equations are solved, whose right-hand sides involve both the background matter and the vacuum effects of quantized fields. It is shown that the de Sitter model is stable with respect to perturbations due to the vacuum corrections. For all other homogeneous isotropic models, taking the vacuum polarization into account makes the singularity occur earlier.