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.

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.

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.

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.

Synthesis of β-D-Glucopyranosides of 6-Substituted 2-(Indol-3-yl)benzothiazoles

2005 ◽  
Vol 70 (1) ◽  
pp. 72-84 ◽  
Author(s):  
Martin Humeník ◽  
Peter Kutschy ◽  
Katarína Valková ◽  
Branislav Horváth ◽  
Vladimír Kováčik ◽  
...  
Keyword(s):  
Potassium Ferricyanide ◽  
Substituted 1

A linear synthesis of substituted 1-(β-D-glucopyranosyl)benzocamalexins starting from indoline and penta-O-acetyl-β-D-glucopyranose was elaborated. Jacobson cyclization of corresponding 4-substituted peracetylated β-D-glucopyranosylindole-3-carbothioanilides employing potassium ferricyanide under basic conditions was a key synthetic step.

Effect of micelle formation of quaternary pyridinium salts on their recyclization to anilines

1981 ◽  
Vol 17 (4) ◽  
pp. 367-369 ◽  
Author(s):  
T. V. Stupnikova ◽  
A. I. Serdyuk ◽  
V. N. Kalafat ◽  
R. S. Sagitullin ◽  
V. P. Marshtupa
Keyword(s):  
Micelle Formation ◽  
Pyridinium Salts ◽  
Quaternary Pyridinium Salts

Untersuchungen an quartären Pyridinium-Salzen, II / Investigation of Quaternary Pyridinium-Salts, II

1973 ◽  
Vol 28 (7-8) ◽  
pp. 471-474 ◽  
Author(s):  
Wolf-Hellmut Gündel
Keyword(s):  
Condensation Product ◽  
Pyridinium Salts ◽  
Quaternary Pyridinium Salts ◽  
Quaternary Salts

Four molecules of quaternary salts of nicotinamide (1 and 4) form a chloroform-soluble condensation product of structure 2 and 5 by action of base under elimination of HX.

scholarly journals Untersuchungen an quartären Pyridinium-Salzen, III / Investigations of Quaternary Pyridinium Salts, III

1974 ◽  
Vol 29 (7-8) ◽  
pp. 556-560 ◽  
Author(s):  
Wolf-Hellmut Gündel ◽  
Bodo Buecher ◽  
Ilse Hagedorn
Keyword(s):  
Condensation Product ◽  
Pyridinium Salts ◽  
Quaternary Pyridinium Salts ◽  
Quaternary Salts ◽  
Model Substances

Four molecules of quaternary salts of nicotinamide form a condensation product of structure 2. It has been studied with the model substances 1d—q which elements of structure promote or prevent formation of the cyclocondensation product.

Untersuchungen an quartären Pyridinium-Salzen, XIV Dihydropyridyl-oximether/Investigations of Quaternary Pyridinium Salts, XIV Dihydropyridyl-oxime-ethers

1981 ◽  
Vol 36 (8) ◽  
pp. 1031-1036 ◽  
Author(s):  
Wolf-H. Gündel
Keyword(s):  
Pyridinium Salts ◽  
Quaternary Pyridinium Salts

Abstract Pyridinium Salts with electron-withdrawing groups in the 3-position react with aliphatic ketoximes under basic conditions to lipophilic addition products, 6-(alkylideniminoxy)-1,6-dihydropyridines.

Sign in / Sign up

Export Citation Format

Share Document