Oxidation of polysubstituted pyridinium salts

1982 ◽  
Vol 47 (5) ◽  
pp. 1494-1502 ◽  
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.

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

1983 ◽  
Vol 48 (11) ◽  
pp. 3307-3314 ◽  
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.

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

1996 ◽  
Vol 61 (1) ◽  
pp. 126-138 ◽  
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.

Base-catalyzed rearrangement of N-(aryloxy)pyridinium salts. Effect of a 3-substituent in the pyridine ring upon orientation. Synthesis of novel tricyclic rings

1983 ◽  
Vol 48 (5) ◽  
pp. 690-695 ◽  
Author(s):  
Rudolph A. Abramovitch ◽  
Muthiah N. Inbasekaran ◽  
Shozo Kato ◽  
Teresa A. Radzikowska ◽  
Piotr Tomasik
Keyword(s):  
Pyridine Ring ◽  
Pyridinium Salts ◽  
Tricyclic Rings

Ferricyanide oxidation of 1-substituted pentaphenylpyridinium salts. A novel route to 1-substituted 2,3,4,5-tetraphenylpyrroles

1989 ◽  
Vol 54 (1) ◽  
pp. 200-205 ◽  
Author(s):  
Stanislav Böhm ◽  
Hanuš Slavík ◽  
Josef Kuthan
Keyword(s):  
Alkaline Medium ◽  
Potassium Ferricyanide

Oxidation of 1-substituted 2,3,4,5,6-pentaphenylpyridinium salts Ia-Ij by potassium ferricyanide in an alkaline medium yields the corresponding 1-substituted 2,3,4,5-tetraphenylpyrroles in 68 to 76% yields. The selectivity of the reaction is discussed.

The oxidation of ortho-anisidine in alkaline medium. A product characterization and an EPR study

1994 ◽  
Vol 72 (5) ◽  
pp. 1351-1356 ◽  
Author(s):  
Adele Bolognese ◽  
Marina Buonanno ◽  
Antonio Cantilena ◽  
Giovanni Musci ◽  
Angelo Alberti
Keyword(s):  
Aqueous Solution ◽  
Alkaline Medium ◽  
Potassium Ferricyanide ◽  
Azo Compounds ◽  
Radical Mechanism ◽  
Radical Species ◽  
Alkaline Aqueous Solution ◽  
Product Characterization ◽  
Alkaline Oxidation

Alkaline oxidation of ortho-anisidine by potassium ferricyanide in alkaline aqueous solution was examined. Azo compounds, a diamine, and para-iminoquinones were isolated from the highly coloured reaction mixture. The reaction was also carried out within the cavity of an EPR spectrometer and two radical species have been detected. Following these product results and EPR studies, a radical mechanism is proposed for the process.

Oxidation of 1,2,3,4,6-substituted pyridinium salts with ferricyanide

1984 ◽  
Vol 49 (2) ◽  
pp. 543-548 ◽  
Author(s):  
Petr Nesvadba ◽  
Josef Kuthan
Keyword(s):  
Reaction Mechanism ◽  
Alkaline Solution ◽  
Quaternary Salt ◽  
Spectral Characteristics ◽  
Potassium Ferricyanide ◽  
Pyridinium Salts ◽  
Pyrrole Derivatives ◽  
Quaternary Pyridinium Salts ◽  
Pyrrole Derivative

Quaternary pyridinium salts IIa-IId are oxidized with alkaline solution of potassium ferricyanide to give a mixture of pyrrole derivatives Ia-Ib and IVa-IVd. The quaternary salt IIe under the same conditions affords a mixture of compounds IVe and V whereas IId gives only the pyrrole derivative IVd. The reaction mechanism is discussed and spectral characteristics of the products are interpreted.

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