Sigma-complexes in the pyrimidine series. 11. 5-arylazo-5-nitro-2,5- and -4,5-dihydro-pyrimidines from anionic sigma complexes of 5-nitropyrimidine

We have studied the reaction of acetonyl anionic sigma complexes of 5-nitropyrimidines with aryldiazonium salts. We have established that, independently of the position of the geminal unit in the sigma complex, electrophilic attack by the diazonium ion occurs at the C₍₅₎ atom with formation of 5-arylazo-5-nitro-2,5- and 4,5-dihydropyrimidines. The latter are unstable and upon isolation are converted to N-methoxycarbonyl-N-(1-acetonyl-2-nitro-2-arylhydrazono)ethyl-O-methylisourea. The structure of one of these compounds has been proven by x-ray diffraction. Under alkaline conditions, aromatization of 2,5-dihydropyrimidines to 5-arylazo-2-acetonylpyrimidines occurs.For Communication 10, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 215–223, February, 1993.     

Reactions of ethyl triphenylphosphoranylideneacetate with fluorinated β-ketoaldehyde derivatives

The reactions of fluorinated β-ketoaldehyde derivatives: β-alkoxyvinyl polyfluoroalkyl ketones 1 and fluorinated β-ketoacetals 2 with ethyl triphenylphosphoranylideneacetate 3 are described. In the case of ketones 1 the result of the reaction is a mixture of products: fluorinated alkoxydienes 5 (Wittig reaction product) and polyfluoroacyl vinyl ylides 7 (Michael addition product). The reaction with fluorinated β-ketoacetals 2 leads to a mixture of E- and Z-isomers of polyfluoroalkyl acrylates 8 and 9, respectively. The influence of the nature of fluorinated substituent and solvent or other factors on the outcome of the reactions are discussed.     

Chemiluminescent Detection of HIV DNA Based on Allosteric Activation of Peroxidase-Mimicking DNAzyme

Homogeneous chemiluminescent method for HIV DNA detection based on allosteric activation of peroxidase-mimicking DNAzyme (PMDNAzyme) was developed. The probes used in the assay contain PMDNAzyme fragment and the additional oligonucleotide sequence complementary to HIV DNA. The interaction of PMDNAzyme fragment and the additional oligonucleotide sequence results in changes in G-quadruplex structure of the PMDNAzyme and decreases peroxidase-like activity of the probe. In the presence of HIV DNA such interaction was destroyed due to the formation of stable duplex between the additional fragment of the probe and DNA-analyte. Consequently, some reorganizations in G-quadruplex structure of the probe are observed, which are accompanied by enhancement of catalytic activity of the PMDNAzyme. The mechanism of the DNA-dependent activation of PMDNAzyme containing probes was confirmed by CD spectroscopy as well as modeling of the probes and their complexes with DNA target. The calibration curves for HIV DNA determination allowed estimating the analytical parameters of the assay. The detection limit value and the linear range were shown to be 0.3 nM and 0.3–15 nM, respectively. The assay sensitivity was high (190000 nM^–1). The values of coefficient of variation (CV) measured within the working range varied less than 4%, which indicates the high accuracy of the proposed assay.     

σ-Complexes in the Pyrimidine Series. 14. Dihydropyrimidine Analogs of Acyclonucleosides. Synthesis of 2,3-Dihydroxypropyl Derivatives of 4-Aryl-6-methyl-5-nitro-1,4(3,4)-dihydropyrimidin-2-ones

Methods have been developed for the synthesis of 5-nitro-1,4- and 5-nitro-3,4-dihydropyrimidin-2-one analogs of acyclonucleosides containing a 2,3-dihydroxypropyl fragment in positions 1 and 3 respectively of the dihydropyrimidine ring.     

4-Trifluoromethylpyrimidines

It is shown that -alkoxyvinyl trifluoromethyl ketones are convenient reagents for the synthesis of 4-trifluoromethylpyrimidines that contain a hydrogen atom or hydroxy, mercapto, and amino groups in the 2 position. The NMR, IR, and UV spectra of the synthesized compounds were studied. The absorption bands in the IR spectra of some of the 4-trifluoromethylpyrimidines were assigned empirically.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 502–511, April, 1991.