Synthesis Of Pyridinium Salts Research Articles

Bio-Active Pyridinium Salts: A Mini-Review on Properties and Selected Reactions

Pyridium salts are very valuable compounds with various activities, especially biological, and therefore their preparation can be very useful in the synthesis of various compounds, such as drugs, dyes or surfactants. In this mini-review authors focused mostly on bioactive properties of pyridinium salts, and main preparations of these compounds such, synthesis pyridinium salts from pyrylium salts via nucleophilic substitution SN(ANRORC), obtaining pyridinium salts via directs arylation, and via Addition at Nitrogen atom, and the last method is synthesis of pyridinium salts via ring opening and re-cyclisation.

Silica‐supported Solvent Approaches More Facile than the Conventional for Erlenmeyer Synthesis with Our Pyridinium Salts

The synthesis of pyridinium salts by both conventional/silica‐supported muffle furnace and microwave approaches is described. We have optimized the Erlenmeyer synthesis of azalactone with various concentrations of our synthesized pyridinium salts. Among these, bromide‐containing pyridinium salts showed excellent catalytic activity than the others.

Synthesis of pyridinium salts from N-substituted dihydropyridines with BF3OEt2 in the absence of added oxidants

N-Substituted dihydropyridines were converted into pyridinium salts with BF3OEt2 as aromatization promoter in reactions that could be conducted without the need of the usually added oxidizing agents, such as quinones, nitrates, peroxides, and chromates. An optimization study employing an N-phenyl Hantzsch ester dihydropyridine (1a) to obtain the corresponding N-phenylpyridinium-containing ammonium quaternary salt (2a) was conducted to define the best conditions for the aromatization reaction: 3equiv of BF3OEt2 at 0°C, in the dark, under atmospheric air in CH2Cl2 to give yields up to 80%. These conditions could also be applied to additional examples of both N-substituted dihydropyridines and 1,4-dihydropyridines.

Zincke's Reaction with Chiral Primary Amines: A Practical Entry to Pyridinium Salts of Interest in Asymmetric Synthesis

The scope of Zincke's synthesis of pyridinium salts using various chiral primary amines and mono- or dialkylpyridines substituted at positions 3, 4 or 5 has been investigated. Salts 6a-f, 9a-i, and 10b,e,h-j were obtained in excellent yields. The results support the accepted mechanism for Zincke's reaction and shows the influence of the solvent on the course of this reaction.

Synthesis of pyridinium salts by the reaction of ?, ?-unsaturated ketones, primary amines, and compounds with labile hydrogen atoms

The reaction of α, β-unsaturated ketones or Mannich bases of ketones with primary aromatic amines and ketones (monoketones or dimedone) in the presence of polyhalo-alkanes leads to pyridinium, 5,6,7,8-tetrahydroquinolinium, or sym-octahydroacridinium salts. The reaction of benxalcyclohexanone with primary aromatic amines and malonodinitrile makes it possible to obtain 2-amino-3-cyano-5,6,7,8-tetrahydroquinolinium salts.