C 98 Cyclization of N-alkylazinium cations with bifunctional nucleophiles. 23. Electrochemical criteria for electrophilicity in 1,4-diazinium cations and their participation in cyclizations with acetoacetamide [Electronic resource] / I. M. Sosonkin, G. L. Kalb, I. V. Kazantseva, M. G. Ponizovskii, V. N. Charushin, O. N. Chupakhin // Chemistry of Heterocyclic Compounds. - 1987. - Vol. 23, № 8. - С. 888-895. - Bibliogr. : p. 894-895 (22 ref.) Рубрики: ХИМИЧЕСКИЕ НАУКИ Кл.слова (ненормированные): PYRAZINIUM -- QUINOXALINIUM -- BENZOQUINOXALINIUM Аннотация: The polarographic reduction potentials E1/2 of the pyrazinium, quinoxalinium, benzoquinoxalinium, pyrido[2,3-b]pyrazinium, and pteridinium cations were determined. Annellation of a benzene ring increases the electrophilicity of the diazinium cations to a greater degree than the introduction of such electron acceptors as aza, aminocarbonyl, or methoxycarbonyl groups. The boundary between the active and inactive 1,4-diazinium salts was determined; cations with E1/2 values more negative than −0.50 V do not form either stable covalent adducts or cyclic diadducts through annellation of the dinucleophiles to the pyrazine ring. \\\\expert2\\nbo\\Chemistry of Heterocyclic Compounds\\1987, v.23, N 8, p. 888.pdf |