V. K. Lusis

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 π-inductive mechanism. 4-(1,4-Dihydropyridyl) functional groups behave as electron donating substituents via an inductive mechanism.

Synthesis of N-unsubstituted and N-methyl derivatives of 4-aryl-2,6-dimethyl-1,2-dihydropyridine-3,5-dicarbonitriles

In the reduction of 2,6-dimethyl-4-arylpyridine-3,5-dicarbonitriles or their N-oxides by sodium borohydride, a mixture of 1,2- and 1,4-dihydropyridine-3,5-dicarbonitriles is formed. 1,2,6-Trimethyl-4-aryl-1,2-dihydropyridine-3,5-dicarbonitriles were obtained by reducing the corresponding pyridinium perchlorates or by alkylating 4-aryl-2,6-dimethyl-1,2-dihydropyridine-3,5-dicarbonitrile derivatives by methyl iodide.

Synthesis of 5-oxoindeno[1,2-b]pyridinium salts

When N-methylated 4-aryl-5-oxo-4,5-dihydroindeno[1,2-b]pyridines are oxidized with hydrogen peroxide in the presence of perchloric acid, in addition to the formation of the indenopyridinium perchlorates, cleavage of the dihydropyridine ring occurs, giving the 2-arylideneindan-1,3-dione.

C- and N-alkylation of 4,5-dihydro-1H-indeno[1, 2-b]pyridine derivatives

Abstract2-Methyl-4-aryl-5-oxo-4,5-dihydro-1H-indeno[1,2-b]pyridine derivatives react with methyl iodide in an aprotic medium in the presence of alkaline agents to give C- and N-alkylation products, viz., 2,4a-dimethyl- and 1,2-dimethyl-4-aryl-5-oxo-4,5-dihydroindeno[1,2-b]pyridines, and with dimethyl sulfate or methyl p-tosylate under the same conditions to give N-methylation products.

MOLECULAR CRYSTAL STRUCTURE AND CHEMICAL PROPERTIES OF 4-PHENYL-3,5-DIETHOXYCARBONYL-1,2,6-TRIMETHYL-1,2-DIHYDROPYRIDINE

The molecular crystal structure of 4-phenyl-3,5-diethoxycarbonyl-1,2,6-trimethyl-1,2-dihydropyridine has been investigated by x-ray structural analysis. The three-dimensional structural properties of the molecule have been compared against the large observed reactivity of the 3-ethoxycarbonyl group with respect to nucleophilic substitution reactions.

Fluorescence of 3,5-diethoxycarbonyl-1,4-dihydropyridine derivatives and their anions

The fluorescence spectra of a group of 3,5-diethoxycarbonyl-1,4-dihydropyridine (1,4-DHP) derivatives were investigated. The introduction of electron-acceptor N-substituents and 2,6-methyl groups decreases Q markedly. The fluorescence spectra of 1,4-DHP anions are shifted bathofluorically, and the Q values are higher than for the corresponding 1,4-DHP. The fluorescence spectra have large Stokesian shifts, which are decreased for 1,4-DHP anions. A good correlation exists between the λmax values of the fluorescence bands of 1,4-DHP anions and the Hammett σp+ constants of the 4-R-aryl substituents.

Acid hydrolysis of N-methyl derivatives of 4-phenyl-5-oxo-4,5-dehydroindeno[1,2-b]pyridine

The splitting of the dihydropyridine ring of N-methyl-substituted 4-phenyl-5-oxo-4,5-dihydroindeno[1,2-b]pyridine in an acid medium takes place at the C-N bond. During the splitting of 1,2-dimethyl-4-phenyl-4,5-dihydroindeno[1,2-b]-pyridine, 4-phenyl-4-(indane-1,3-dion-2-yl)butan-2-one is formed, while in the case of the 3-ethoxycarbonyl derivative of indenopyridine, together with the Michael retroreaction leading to 2-benzylideneindane-1,3-dione, a recyclization of the intermediate product into a derivative of dihydroindeno-2-pyridone takes place.

Electrolytic oxidation of 2,6-dimethyl-3,5-bis(ethoxycarbonyl)-1,2-dihydropyridines in acetonitrile on platinum electrodes

Free cation radicals, which subsequently undergo deprotonation to neutral radicals and disproportionation to give the starting molecules and pyridinium cations, are formed in the electrochemical oxidation of N-substituted 2,6-dimethyl-3,5-bis-(ethoxycarbonyl)-1,3-dihydropyridines on a rotating disk electrode with a ring in solution in acetonitrile. The primary cation radicals were identified by electrochemical generation in a cell placed in the resonator of an EPR spectrometer, and the hyperfine structures of the corresponding EPR spectra were studied.

New derivatives of 4-aryl-2,6-dimethyl-3,5-diacetyl-1,4- and 1,2-dihydropyridines

Abstract4-Aryl-1,2,6-trimethyl-3,5-diacetyl-1,4-dihydropyridines and the corresponding pyridinium salts, which upon reduction with NaBH4 form 4-aryl-1,2,6-trimethyl-3,5-diacetyl-1,2-dihydropyridines, were synthesized.

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 π-electron system of the ring. The introduction of an alkyl group at the nitrogen atom facilitates the electrical oxidation of 1,4-DHP.