N. E. Shchepina

Preparation of fused n-phenyl-substituted pyridinium derivatives by direct phenylation with nucleogenic phenyl cations

The direct phenylation of a nitrogen atom has been carried out for the first time in fused pyridine derivatives by ion-molecular interaction of nucleogenic phenyl cations with acridine and phenanthridine. N-Phenylacridinium and -phenanthridinium compounds, which are sensitive markers for biological investigations, were obtained labeled with tritium.

The reaction of direct phenylation by nucleogenic cations as a method of synthesis of unknown or complicated tritium labeled compounds

As a result of ion-molecular reactions of nucleogenic phenyl cations, generated by tritium β-decay in polytritiated benzene, with nucleophilic centers of investigated substrates the direct phenylation has been realized at first time and unknown tritium labeled aromatic derivatives of polyvalent fluorine together with the different N-phenyl substituted pyridinium compounds which are important syntones for biological and medical investigations have been synthesized.

Pathways of ion–molecular interactions of nucleogenic phenyl cations with the nucleophilic centers of picolines

Background The nuclear-chemical method brought unique opportunity for synthesis of unknown and hardly available organic compounds. Presence of tritium labeling allows one-step preparation of radioactive markers for the investigation of chemical and biological processes. Methods The ion–molecular reactions of nucleogenic phenyl cations with 4-picoline have been carried out. The phenyl cations were generated by spontaneous tritium β-decay within the tritium-labeled benzene. Both additions to the nitrogen and substitutions about the aromatic ring were able to be studied simultaneously. Results Unusual substitutions on both the α- and β-positions of the ring system have been revealed. Conclusion By unknown direct phenylation of nitrogen atom tritium-labeled N-phenylpicolinium derivatives, perspective biological markers have been synthesized.

Synthesis of arylhalonium compounds [including (4-methylphenyl) phenylfluoronium] by the nuclear–chemical method

Abstract The nuclear–chemical method has been used for the synthesis of previously unknown multivalent fluorine derivatives, namely (4-methylphenyl)phenylfluoronium. The synthesis includes the ion-molecular reaction of free phenyl cations generated by tritium β-decay with 4-methylhalobenzenes. The influence of the halogen atom (F, Cl, Br, I) as well as effects of the methyl substituent on the yields of the corresponding halonium compounds have been investigated.

Ion-molecular reactions of free phenylium ions, generated by tritium β-decay with bidentate arenes

Abstract Generation of free phenylium ions, obtained by tritium β-decay and their ion-molecular reactions with bidentate arenes are described. The elaborated nuclear-chemical method has been used for the synthesis of tritium labeled organic derivatives using halobenzenes. Two alternative pathways for interaction of the phenylium ion with the bidentate arene, addition to the lone pair of the halogen or substitution on the aromatic ring, were revealed.

Investigation of the phenylation of methyl-quinolines using tritium-labeled nucleogenic phenyl cations

The phenylation of methylquinolines by nucleogenic phenyl cations was studied. This reaction led to a product mixture through electrophilic addition and electrophilic substitution, with composition depending on the methyl substituent position. In the case of 4-methylquinoline, the electron-donating methyl group in the para position markedly increased the yield of N-phenylquinolinium derivative, while the low yield of the quinolinium salt in the case of 8-methylquinoline was due to the two factors - low basicity of the nitrogen atom in comparison to 4-methylquinoline and steric hindrance by the methyl group, which led to predominant electrophilic substitution.

One-step synthesis of quaternary phenyl isoquinolinium compounds labeled with tritium

A procedure was suggested for one-step synthesis of quaternary phenyl isoquinolinium compounds labeled with tritium by direct phenylation with nucleogenic phenyl cations of the lone electron pair of the nitrogen atom in isoquinoline.

Nuclear-chemical synthesis of tritium-labeled phenyl-substituted picoline derivatives

Ion-molecule reactions of free phenyl cations with six-membered nitrogen-containing heterocyclic compounds: α-, β-, and γ-picolines, were studied. Phenyl cations were generated by tritium β-decay in double-labeled benzene. The mechanism of competing reactions of electrophilic addition to the nitrogen heteroatom in the ring and electrophilic substitution of the C-H bond in the pyridine ring was examined. The effect of methyl substituent in the pyridine molecule on the reaction pathway was evaluated. A one-step procedure for nuclear-chemical synthesis of tritium-labeled N-phenylpicolinium salts and phenyl-substituted picolines was developed.

Fluorinated nucleogenic phenyl cations and nuclear-chemical route to previously unknown heterocyclic derivatives

A new reactive species, fluorinated phenyl cation generated by β-decay of tritium in difluoroditritiobenzene, was used for introducing fluorinated phenyl fragment into organic compounds. Studies of ion–molecule reactions have shown that, similarly to the unsubstituted nucleogenic phenyl cation, p-difluorophenyl cation directly phenylates the N atom in the heterocyclic ring of quinoline. The nuclear-chemical method allows not only generation of nucleogenic species of various structures, but also one-step synthesis of previously unknown and difficultly accessible heterocyclic derivatives labeled with tritium.

New Way of Direct Nitrogen Atom Phenylation in Quinoline Derivatives

Comparison of ion-molecular reactions of free-phenyl cations generated by tritium β-decay with 2-methyl- and 2-phenylquinolines has been investigated. The reaction of direct nitrogen atom phenylation with the help of nucleogenic phenyl cations has been fulfilled for the first time and a new one-step synthesis of tritium-labeled N-phenyl-2-phenylquinolinium salt—lipophilic radioactive biological marker has been elaborated.