Voltamperometry of 1,4-dihydropyridine derivatives

Thirty-nine -substituted 1,4-dihydropyridine derivatives were subjected to electrochemical oxidation on a rotating platinum microelectrode in acetonitrile, and the E_p (E_1/2) values were measured. A satisfactory linear correlation between the E_p and Taft. ^* constants of the substituents in the position was observed. A linear correlation of the E_p values with the ⁰, - and ^– constants also exists.See [1] for communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1525–1529, November. 1975.     

Effect of substituents in the dihydropyridine ring on the reactivity of the ester group of 3,5-dialkoxycarbonyl-1,4-dihydropyridines

The reactivity of the ester group of 3,5-dialkoxycarbonyl-1,4-dihydropyridines upon reaction with nucleophilic reagents increases when substituents are absent in the ortho positions relative to the ester group and also in the case of steric disruption of the coplanarity of the -aminovinylcarbonyl system when substituents are introduced at the nitrogen atom in 2,6-dimethyl derivatives. Mono- and dicarboxylic acids were obtained by hydrolysis of such esters. Thus use of esters of propiolic acid esters and arylamines in the Hantzsch synthesis made it possible to obtain 1-aryl-2,6-unsubstituted derivatives of 1,4-dihydropyridine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1072–1077, August, 1982.     

Relation between the vectors E and S for a plastic material in succesive biaxial tension

The local strains theory is used to determine the values of the components of the vector E{E₁, E₂} in five-dimensional space for a material subjected to successive biaxial tension at degrees of nonlinearity n=3 and n=5. The relation between the vectors E and S and the tangents to the loading and strain trajectories is considered together with the relation between the moduli E of the strains for simple and complex loading.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 6, pp. 975–979, November–December, 1969.     

13C-NMR spectra of substituted 1,4-dihydropyridines

It has been found that the electron shift in the C₍₂₎=C₍₃₎ bond, under the influence of the substituent attached to the nitrogen atom and the substituents in the 3- and 5-positions, occurs via a -inductive mechanism. 4-(1,4-Dihydropyridyl) functional groups behave as electron donating substituents via an inductive mechanism.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1232–1238, September, 1989.     

1-aryl- and 1-benzyl-3,5-diethoxycarbonyl-1,4-dihydropyridines

The possibility has been studied of using anilines in the Hantzsch synthesis. It has been shown that, with the exception of those containing strong electron-accepting substituents, they take part in this reaction with the formation of 1-aryl-1,4-dihydropyridines. The reaction largely depends on the nature of the substituents in the aniline and in the benzaldehyde and is promoted by electron-accepting substituents in the aldehyde and electron-donating substituents in the amine. The mechanism of the reaction is discussed. A number of 1-benzyl-1,4-dihydropyridines have been synthesized. The UV, IR, and PMR spectra and the electro-oxidation of the compounds obtained have been studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 493–501, April, 1980.     

Retardation trace in tension with subsequent compression in the transverse direction

The local strains theory is employed to determine the strain components ₁ and ₂ in five-dimensional space in the case of tension with subsequent compression at nonlinearities n=3 and n=5. The relations between the vectors and S and the tangents to the loading and deformation trajectories and between the moduli of the strain for complex and simple loading are considered.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 4, pp. 597–602, July–August, 1969.     

Formation of a derivative of 3,3,5-tricarbonyl-1,2,3,4-tetrahydropyridine under the conditions of the hantzsch synthesis

An ester of p-nitrobenzoylacetic acid is cyclized under the action of hexamethyl-enetetramine and ammonium acetate to 3,5-diethoxycarbonyl-3-p-nitrobenzoyl-6-p-nitrophenyl-1,2,3,4-tetra-hydropyridine, the structure of which has been established by NMR, UV, IR, and mass spectra and also by its chemical reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 501–505, April, 1986.     

Effect of loading history on changes in the characteristic Angles and the length of the retardation trace

The local strains theory and the theory of small elastoplastic strains are used to determine the values of the components of the plastic strain vector {₁, ₂} for nonlinearity n=3 in five-dimensional Euclidean space in the case of complex loading along a two-segment broken line, when both tensile and compressive stresses are present in each loading stage. The relation between the vectors , and S and the tangents to the deformation and loading trajectories are examined. Values of the retardation trace are obtained in terms of the loading history. Numerical results have been derived with the aid of a BÉSM-3M computer.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 1, pp. 92–97, January–February, 1971.     

N-alkylation of 1,4-dihydropyridine-3,5-dicarboxylic acid esters

Alkylation of the anions of 1,4-dihydropyridines (1,4-DHP) formed by treatment of sodium hydride in aprotic solvents gave 1-alkyl(up to C₆H₁₃)-3,5-bis(ethoxycarbonyl)- and 1-alkyl-3,5-bis(aryloxycarbonyl)-1,4-DHP. The presence of a substituent in the 4 position increases the reactivity of the 1,4-DHP anion in the alkylation reaction. The absorption maximum in the UV spectra of the 1,4-DHP anion is shifted 100 nm bathochromically as compared with the neutral molecule. The longwave absorption maximum in the UV spectra of 1-alkyl-1,4-DHP is shifted hypsochromically as compared with the 1-unsubstituted compounds; this is explained by steric hindrance of the conjugation of the C=O groups with the -electron system of the ring. The introduction of an alkyl group at the nitrogen atom facilitates the electrical oxidation of 1,4-DHP.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1508–1513, November, 1978.