S 10 S-N(H) reactions of pyrazine N-oxides and 1,2,4-triazine 4-oxides with CH-active compounds [Electronic resource] / D. N. Kozhevnikov, I. S. Kovalev, A. M. Prokhorov, V. L. Rusinov, O. N. Chupakhin // Russian Chemical Bulletin (Translation of Izvestiya Akademii Nauk, Seriya Khimicheskaya). - 2003. - Vol. 52, № 7. - P1588-1594 Рубрики: ХИМИЧЕСКИЕ НАУКИ Аннотация: Nucleophilic substitution of hydrogen in pyrazine N-oxides under the action of CH-active compounds requires activation with acylating agents. This activation facilitates aromatization of intermediate H adducts via elimination of the acid residue to form substituted pyrazines. More electrophilic 1,2,4-triazine 4-oxides react with carbanions derived from CH-active compounds without additional activation according to a scheme, which has previously been unknown for azine N-oxides. This scheme involves aromatization of H adducts through elimination of water by the E1cb mechanism. The reaction products occur in DMSO-d6 solutions predominantly as 6-methylene-1,6-dihydropyrazines and 5-methylene-4,5-dihydro-1,2,4-triazines.??nucleophilic substitution of hydrogen - 1,2,4-triazine 4-oxide - pyrazine 1-oxide - carbanion - CH-active compounds?? \\\\Expert2\\nbo\\Russian Chemical Bulletin\\2003, 52 (7), 1588.pdf |