Pyridinium Salts as Organophosphate Antagonists

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

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Oxidation of polysubstituted pyridinium salts

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19821494 ◽

1982 ◽

Vol 47 (5) ◽

pp. 1494-1502 ◽

Cited By ~ 10

Author(s):

Petr Nesvadba ◽

Josef Kuthan

Keyword(s):

Alkaline Medium ◽

Electrophilic Substitution ◽

Pyridine Ring ◽

Potassium Ferricyanide ◽

Pyridinium Salts ◽

Complex Reaction

Oxidation of 1-substituted 2,4,6-triphenylpyridinium salts Ia-Ij with potassium ferricyanide in an alkaline medium was accompanied by contraction of the pyridine ring and formation of 1,2,3,5-tetrasubstituted pyrroles II. The derivative IIf underwent facile electrophilic substitution in the position 4. Contrary to compounds Ia-Ij, the 1-substituted-2,6-diphenylpyridinium salts IIIa,b were oxidized to give a complex reaction mixture containing 4-pyridones IVa,b.

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A new heterocyclic ring closure in ferricyanide oxidation of 2,4,6-triphenylpyridinium salts

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19833307 ◽

1983 ◽

Vol 48 (11) ◽

pp. 3307-3314 ◽

Cited By ~ 6

Author(s):

Petr Nesvadba ◽

Petr Štrop ◽

Josef Kuthan

Keyword(s):

Alkaline Solution ◽

Heterocyclic Ring ◽

Potassium Ferricyanide ◽

Probable Mechanism ◽

Ring Closure ◽

Pyridinium Salts ◽

Mechanism Of Formation ◽

Pyrrole Derivatives ◽

Quaternary Pyridinium Salts ◽

Heterocyclic Derivatives

The quaternary pyridinium salts Ia-Ic react with alkaline solution of potassium ferricyanide to give the condensed heterocyclic derivatives IIIa, b, IV, whereas the salts Id-If give the pyrrole derivatives IIa-IIc under the same conditions. The diaza heterocycle IIIa reacts with methyl iodide to give methoiodide V, whereas by action of bromine it produces two monobromo derivatives VIa, b. The pyrrole derivatives IIa, b give monobromo derivatives IId, e on bromination. A probable mechanism of formation of the heterocyclic derivatives is discussed.

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Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19802766 ◽

1980 ◽

Vol 45 (10) ◽

pp. 2766-2771 ◽

Cited By ~ 8

Author(s):

Antonín Lyčka

Keyword(s):

Heavy Water ◽

Nmr Spectra ◽

Chemical Shifts ◽

Coupling Constants ◽

Pyridinium Salts ◽

Nmr Signals ◽

C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

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Sterically Crowded Heterocycles. III. A General Approach to Imidazo[1,2-a]pyridines by Ferricyanide Oxidation of Quaternary Pyridinium Salts

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19960126 ◽

1996 ◽

Vol 61 (1) ◽

pp. 126-138 ◽

Cited By ~ 6

Author(s):

Richard Kubík ◽

Stanislav Böhm ◽

Iveta Ruppertová ◽

Josef Kuthan

Keyword(s):

Potassium Hydroxide ◽

Potassium Ferricyanide ◽

Pyridinium Salts ◽

Oxidizing Agents ◽

Quaternary Pyridinium Salts ◽

Substituted 1

Substituted 1-(pyridin-2-yl)-2,4,6-triphenylpyridinium perchlorates 1b-1e were converted with potassium ferricyanide and potassium hydroxide to sterically crowded 2-phenyl-3-[(Z)-1,3-diphenyl-3-oxopropenyl]imidazo[1,2-a]pyridines 2b-2e accompanied by minor isomeric 2-benzoyl-3,5-diphenyl-1-(pyridin-2-yl)pyrroles 3c-3e. 4-Phenyl-2,6-di(4-substituted phenyl)-1-(pyridin-2-yl)pyridinium salts 4a, 4b gave exclusively corresponding imidazo[1,2-a]pyridines 5a, 5b while the ferricyanide oxidation of 1-(5-iodo- and 5-cyanopyridin-2-yl)-2,4,6-triphenylpyridinium perchlorates 6a, 6b led to mixtures of major imidazo[1,2-a]pyridines 7a-7c and minor pyrroles 8a-8c. Some mechanistic aspects of the oxidation procedure are discussed in connection with a resistance of 2,6-diphenyl-1,3,5-trimethylpyridinium perchlorate (9c) towards the oxidizing agents.

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