Polarographic reduction of adenine and its 9-(α,ω-dihydroxy-2-alkyl) derivatives

The polarographic reduction of adenine and its 9-(,)-dihydroxy-2-alkyl) derivatives on a short-period mercury electrode in strongly acidic media is determined by the rate of diffusion of the corresponding cations and, at pH values that exceed the pK_a values, by the kinetics of surface protonation of the uncharged molecules; this was proved by the dependence of the limiting current on the height of the mercury column, the temperature, and the depolarizer concentration. The polarographic reduction of adenine, adenosine, 9-(,-di-hydroxy-2-alkyl)adenines, and the corresponding phosphates in acidic media proceeds with the loss of sic electrons per molecule. The similar trends of the change in the half-wave potentials and the numerical pK_a values is associated with the fact that the site of protonation is simultaneously the site of nucleophilic attack by the electron during electrical reduction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1675–1678, December, 1977.     

Polarographic investigation of the mobility of halogen atoms in halogen-substituted components of nucleic acids

In order to establish quantitatively the reducibility of halogen-substituted components of nucleic acids, the half-wave potentials (E_1/2) of their electrochemical reduction have been determined. The electrochemical reduction of all compounds takes place in the interval from –0.5 to –1.8 V and consists in the splitting off of the halogen atom (iodine, bromine) from the given molecule. The iodine derivatives are reduced much more readily (500–800 mV) than the bromine derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1404–1408, October, 1992     

Synthesis and properties of derivatives of 1,4-dihydropyrimidine-5-carboxylic acid

1,4-Dihydropyrimidines were synthesized by reductive dethionation of the corresponding 2-thiono-4-aryl-1,2,3,4-tetrahydropyrimidine-5-carboxylic acid derivatives, and some of their properties were studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1223–1227, September, 1986.     

Formation of furo- and difuro-1,4-dihydropyridines in the bromination 0f 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(o-nitrophenyl)-1,4-dihydropyridine

Furo- and difuro-1,4-dihydropyridines were obtained by bromination of 2,6-dimethyl-3,5-dimethoxycarbonyl-4-(o-nitrophenyl)-1,4-dihydropyridine with mild brominating agents (pyridinium bromide perbromide, N-bromosuccinimide, and dioxane dibromide).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1227–1232, September, 1987.     

Polarographic reduction of 2-(4-pyridyl)indane-1,3-diones in dimethylformamide

The trend of the electrical reduction of isomeric 2-(4-pyridyl)indane-1,3-diones in dimethylformamide (DMF) was studied by classical and ac polarography, millicoulometry, ESR spectroscopy, and cyclical voltamperometry with a steady-state mercury electrode. The first reversible one-electron step leads to the formation of relatively stable anion radicals, which can be recorded by means of ESR spectroscopy. The corresponding dimers are detected in the course of prolonged electrolysis at a constant potential (at the level of the limiting current of the first wave). The second nonreversible step in the electrical reduction involves the indane-1,3-dionyl grouping and the pyridinium ring. Owing to their dipolar structure, the investigated compounds are reduced with considerably greater difficulty (by 400–550 mV) than the unsubstituted N-methylpyridinium salt.Translated from Geterotsiklicheskikh Soedinenii, No. 8, pp. 1097–1102, August, 1977.     

Study of the electrical oxidation of 2,6-dimethyl-3,5-diethoxy-carbonyl-1,4-dihydropyridines in acetonitrile by means of a rotating disk electrode with a ring

It is shown that the electrochemical oxidation of esters of 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylic acids in anhydrous acetonitrile takes place as a one-electron process, while the final products of the transformations (pyridines or pyridinium salts) are formed as a result of disproportionation of the intermediate radicals. When 1–2% (by volume) water is added, the oxidation mechanism changes substantially, and the electrochemical process becomes a two-electron process.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1263–1267, September, 1980.     

Electrochemical conversions of 5-oxo-1,4-dihydroindeno[1,2-b]pyridine derivatives

The electrochemical oxidation and reduction potentials of 9 derivatives of 5-oxo-1,4-dihydroindeno[1,2-b]pyridine in acetonitrile on a glassy graphite disk electrode have been established. Indenodihydropyridines are oxidized with considerably greater difficulty and reduced considerably more easily than the corresponding 3,5-diethoxycarbonyl derivatives of 1,4-dihydropyridines which is explained by the presence of the cyclopentane fragment which ensures the coplanarity of the carbonyl groups with the aminovinyl system of the heterocycle. The mechanism of electrooxidation has been studied by the rotating disk electrode with a ring method which revealed the reasons for the process.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, 1992 pp. 1223–1229, September, 1992.